Exploring Manganese Fractionation Using a Sequential Extraction Method to Evaluate Welders' Gas Metal Arc Welding Exposures during Heavy Equipment Manufacturing.

PubMed

Hanley, Kevin W; Andrews, Ronnee; Bertke, Steven; Ashley, Kevin

2017-01-01

The National Institute for Occupational Safety and Health (NIOSH) has conducted an occupational exposure assessment study of manganese (Mn) in welding fume at three factories where heavy equipment was manufactured. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. One hundred nine worker-days were monitored for either total or respirable Mn during gas metal arc welding. The samples were analyzed using an experimental method to separate different Mn fractions based on selective chemical solubility. The full-shift total particle size Mn time-weighted average (TWA) breathing zone concentrations ranged 0.38-26 for soluble Mn in a mild ammonium acetate solution; 3.2-170 for Mn0,2+ in acetic acid; 3.1-290 for Mn3+,4+ in hydroxylamine-hydrochloride; and non-detectable (ND)-130 µg m-3 for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all the total particulate Mn TWA fractions yielded results that ranged from 6.9 to 610 µg m-3. The range of respirable size Mn TWA concentrations were 0.33-21 for soluble Mn; 15-140 for Mn0,2+; 14-170 for Mn3+,4+; 5.3-230 for insoluble Mn; and 36-530 µg m-3 for Mn (sum of fractions). Total particulate TWA GM concentrations of the Mn (sum) were 53 (GSD = 2.5), 150 (GSD = 1.7), and 120 (GSD = 1.8) µg m-3 for the three separate factories. Although all of the workers' exposures were measured below the OSHA regulatory permissible exposure limit and NIOSH recommended exposure limit for Mn, 70 welders' exposures exceeded the ACGIH Threshold Limit Values® for total Mn (100 µg m-3) and 29 exceeded the recently adopted respirable Mn TLV (20 µg m-3). This study shows that a welding fume exposure control and management program is warranted for Mn, which includes improved exhaust ventilation and may necessitate the use of respiratory protection, especially for welding parts that impede air circulation. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2017.

Formaldehyde Exposures in a University Anatomy Laboratory

NASA Astrophysics Data System (ADS)

Winkler, Kyle William

Air sampling studies were conducted within a university anatomical laboratory during the embalmment of a cadaver in order to determine if dangerous concentrations of formaldehyde existed. Three air sampling studies were conducted in the anatomical laboratory on three separate days that a cadaver was being embalmed. Samples were collected and analyzed using the Occupational Safety and Health Administration (OSHA) Sampling and Analytical Methods: Method 52. Each air sampling study sampled for short term exposure limit (STEL) and time weighted mean (TWA) breathing zone formaldehyde concentrations as well as area TWA formaldehyde concentrations. A personal aldehyde monitor was also used in each air sampling study to sample for breathing zone formaldehyde concentrations. Measured TWA mean exposures to formaldehyde ranged from 0.15--1.3 parts per million (ppm), STEL formaldehyde exposures ranged from 0.019--0.64 ppm, and eight-hour TWAs ranged from 0.03 to 3.6 ppm. All 8-hour TWA formaldehyde concentrations sampled in the anatomy laboratory during an embalmment were less than the permissible exposure limit (PEL) required by OSHA.

Isocyanate exposure and occupational asthma: a case-referent study

PubMed Central

Meredith, S; Bugler, J; Clark, R

2000-01-01

OBJECTIVE—To examine the quantitative relation between exposure to isocyanates and occupational asthma, and to explore the role of atopy and smoking in occurrence of the disease.
METHOD—A case-referent study was undertaken of cases from two manufacturing companies (A and B) from which referents without disease could be selected and reliable exposure measurements were available. In company A, 27 cases mainly attributed to toluene diisocyanate (TDI) were matched to 51 referents on work area, start and duration of employment, sex, and age. Exposures were estimated from existing measurements by job category. In company B there were seven cases attributed to 4,4'-diphenylmethane diisocyanate (MDI) in two areas of the plant; 12 non-cases from the same areas were used as referents. Personal exposure measurements were available for all cases and 11 referents.
RESULTS—No difference in peak exposures between cases and referents was found in either plant; but in both, time weighted average (TWA) exposures at the time of onset of asthma were higher for cases. In A, the mean TWA exposure for cases was 1.5 (95% confidence interval (95% CI) 1.2 to 1.8) ppb compared with 1.2 (1.0 to 1.4) ppb for referents. From a matched analysis, the odds ratio (OR) associated with 8 hour TWA exposure to isocyanates greater than 1.125 ppb (the median concentration for the referent group) was 3.2 (95% CI 0.96 to 10.6; p=0.06). Occupational asthma was associated with a pre-employment history of atopic illness (OR 3.5, p=0.04) and, less strongly, with smoking (OR 2.1, p=0.14). In B, small numbers limited analysis, but three of seven cases had at least one TWA exposure measurement greater than 5 ppb compared with one of 11 referents (OR 7.5, p=0.09).
CONCLUSION—Asthma can occur at low concentrations of isocyanates, but even at low concentrations, the higher the exposure the greater the risk. By contrast with other studies, smoking and atopy seemed to increase the odds of occupational asthma due to isocyanates, but did not affect the estimate of risk associated with exposure.


Keywords: occupational asthma; isocyanates PMID:11077012

Exposure data from multi-application, multi-industry maintenance of surfaces and joints sealed with asbestos-containing gaskets and packing.

PubMed

Boelter, Fred; Simmons, Catherine; Hewett, Paul

2011-04-01

Fluid sealing devices (gaskets and packing) containing asbestos are manufactured and blended with binders such that the asbestos fibers are locked in a matrix that limits the potential for fiber release. Occasionally, fluid sealing devices fail and need to be replaced or are removed during preventive maintenance activities. This is the first study known to pool over a decade's worth of exposure assessments involving fluid sealing devices used in a variety of applications. Twenty-one assessments of work activities and air monitoring were performed under conditions with no mechanical ventilation and work scenarios described as "worst-case" conditions. Frequently, the work was conducted using aggressive techniques, along with dry removal practices. Personal and area samples were collected and analyzed in accordance with the National Institute for Occupational Safety and Health Methods 7400 and 7402. A total of 782 samples were analyzed by phase contrast microscopy, and 499 samples were analyzed by transmission electron microscopy. The statistical data analysis focused on the overall data sets which were personal full-shift time-weighted average (TWA) exposures, personal 30-min exposures, and area full-shift TWA values. Each data set contains three estimates of exposure: (1) total fibers; (2) asbestos fibers only but substituting a value of 0.0035 f/cc for censored data; and (3) asbestos fibers only but substituting the limit of quantification value for censored data. Censored data in the various data sets ranged from 7% to just over 95%. Because all the data sets were censored, the geometric mean and geometric standard deviation were estimated using the maximum likelihood estimation method. Nonparametric, Kaplan-Meier, and lognormal statistics were applied and found to be consistent and reinforcing. All three sets of statistics suggest that the mean and median exposures were less than 25% of 0.1 f/cc 8-hr TWA sample or 1.0 f/cc 30-min samples, and that there is at least 95% confidence that the true 95th percentile exposures are less than 0.1 f/cc as an 8-hr TWA.

Assessment of Occupational Noise Exposure among Groundskeepers in North Carolina Public Universities

PubMed Central

Balanay, Jo Anne G.; Kearney, Gregory D.; Mannarino, Adam J.

2016-01-01

Groundskeepers may have increased risk to noise-induced hearing loss due to the performance of excessively noisy tasks. This study assessed the exposure of groundskeepers to noise in multiple universities and determined the association between noise exposure and variables (ie, university, month, tool used). Personal noise exposures were monitored during the work shift using noise dosimetry. A sound level meter was used to measure the maximum sound pressure levels from groundskeeping equipment. The mean Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH) time-weighted average (TWA) noise exposures were 83.0 ± 9.6 and 88.0 ± 6.7 dBA, respectively. About 52% of the OSHA TWAs and 77% of the NIOSH TWAs exceeded 85 dBA. Riding mower use was associated with high TWA noise exposures and with having OSHA TWAs exceeding 85 and 90 dBA. The maximum sound pressure levels of equipment and tools measured ranged from 76 to 109 dBA, 82% of which were >85 dBA. These findings support that groundskeepers have excessive noise exposures, which may be effectively reduced through careful scheduling of the use of noisy equipment/tools. PMID:27330303

Evaluation of exposures of hospital employees to anesthetic gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambeth, J.D.

1988-01-01

Hospital employees who work in hospital operating and recovery rooms are often exposed to a number of anesthetic gases. There is evidence to support the belief that such exposures have led to higher rates of miscarriages and spontaneous abortions of pregnancies among women directly exposed to these gases than among women not exposed. Most of the studies assessing exposure levels were conducted prior to the widespread use of scavenging systems. Air sampling was conducted in hospital operatories and recovery rooms of three large hospitals to assess the current exposure levels in these areas and determine the effectiveness of these systemsmore » in reducing exposures to fluoride-containing anesthetic gases. It was determined that recovery-room personnel are exposed to levels of anesthesia gases that often approach and exceed the recommended Threshold Limit Value-Time Weighted Average (TLV-TWA) of 2.0 ppm. Recovery-room personnel do not have the protection from exposure provided by scavenging systems in operating rooms. Operating-room personnel were exposed to anesthesia gas levels above the TLV-TWA only when patients were masked, or connected and disconnected from the scavenging systems. Recovery-room personnel also need to be protected from exposure to anesthesia gases by a scavenging system.« less

Exposure to MRI-related magnetic fields and vertigo in MRI workers.

PubMed

Schaap, Kristel; Portengen, Lützen; Kromhout, Hans

2016-03-01

Vertigo has been reported by people working around magnetic resonance imaging (MRI) scanners and was found to increase with increasing strength of scanner magnets. This suggests an association with exposure to static magnetic fields (SMF) and/or motion-induced time-varying magnetic fields (TVMF). This study assessed the association between various metrics of shift-long exposure to SMF and TVMF and self-reported vertigo among MRI workers. We analysed 358 shifts from 234 employees at 14 MRI facilities in the Netherlands. Participants used logbooks to report vertigo experienced during the work day at the MRI facility. In addition, personal exposure to SMF and TVMF was measured during the same shifts, using portable magnetic field dosimeters. Vertigo was reported during 22 shifts by 20 participants and was significantly associated with peak and time-weighted average (TWA) metrics of SMF as well as TVMF exposure. Associations were most evident with full-shift TWA TVMF exposure. The probability of vertigo occurrence during a work shift exceeded 5% at peak exposure levels of 409 mT and 477 mT/s and at full-shift TWA levels of 3 mT and 0.6 mT/s. These results confirm the hypothesis that vertigo is associated with exposure to MRI-related SMF and TVMF. Strong correlations between various metrics of shift-long exposure make it difficult to disentangle the effects of SMF and TVMF exposure, or identify the most relevant exposure metric. On the other hand, this also implies that several metrics of shift-long exposure to SMF and TVMF should perform similarly in epidemiological studies on MRI-related vertigo. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

An exposure study of bystanders and workers during the installation and removal of asbestos gaskets and packing.

PubMed

Mangold, Carl; Clark, Katherine; Madl, Amy; Paustenbach, Dennis

2006-02-01

From 1982 until 1991, a series of studies was performed to evaluate the airborne concentration of chrysotile asbestos associated with replacing gaskets and packing materials. These studies were conducted by the senior author in response to concerns raised by a report from the Navy in 1978 on asbestos exposures associated with gasket work. A series of studies was conducted because results of those who worked with gaskets within the Navy study did not address the background concentrations of asbestos in the work areas, which may have been significant due to the presence of asbestos insulation in the ships and shipyards. The intent of the studies performed from 1982 through 1991 was to re-create the Navy's work practices in a contaminant-free environment during an 8-hour workday (so the data could be compared with the OSHA permissible exposure limit [PEL]). Samples were collected to characterize personal and area airborne asbestos concentrations associated with the formation, removal, and storage of gaskets, as well as the scraping of flanges and the replacement of valve packing. The results indicate that the 8-hour time-weighted average (TWA) exposures of pipefitters and other tradesmen who performed these activities were below the current PEL and all previous PELs. Specifically, the highest average 8-hour TWA concentration measured for workers manipulating asbestos gaskets during this study was 0.030 f/cc (during gasket removal and flange face scraping onboard a naval ship). Likewise, the 8-hour TWA breathing zone concentrations of a worker removing and replacing asbestos valve packing did not exceed 0.016 f/cc. In most cases, the concentrations were not distinguishable from ambient levels of asbestos in the ships or the general environment. These results are not surprising given that asbestos fibers in gasket materials are encapsulated within a binder.

[Occupational exposure to gases emitted in mild and stainless steel welding].

PubMed

Matczak, W; Gromiec, J

2001-01-01

The objective of this work was to select optimal methods for determination of toxic gases (NOx, NO2, CO, CO2, O3) and to evaluate occupational exposure of welders to those gases. The survey covered workers employed in shipyards, and other metal product fabrication plants engaged in welding mild and stainless steel by different techniques (manual metal are, metal active gas, tungsten inert gas welding; gas, plasma, laser cutting and resistance welding). Personal and stationary air samples were collected to determine time weighted average (TWA) and short-term concentrations of gases. For determination of nitrogen oxides the following analytical techniques were employed: spectrophotometry with collection on liquid and solid sorbents and ion chromatography with collection on solid sorbents. All the gases were determined also by automatic or direct reading methods: flow or diffusion detector tubes and photometric and electrochemical analyzers. The determined TWA concentrations were below respective Maximum Allowable Concentrations (MAC) but exposure limits for short term exposure were exceeded in some cases. The average NO2 i NOx ratio was 1:4. According to Polish regulations regarding the MAC value for nitrogen oxides the analytical method should enable determination of total NOx by either direct or indirect simultaneous determination of both NO and NO2. The applicability of the spectrophotometric method of analysis of atmospheric NOx to determination of low NOx concentrations at welders working posts has been confirmed.

Health-hazard evaluation report HETA 91-298-2182, Gibson Flatiron, Erica Shell Manufacturing, Bozeman, Montana

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCammon, C.S.

1992-02-01

In response to a request from the Montana State Health Department, an evaluation was undertaken of exposures to wood dust and lacquer vapors at the Gibson Flatiron/Erica Shell Manufacturing Companies (SIC-3931), Bozeman, Montana. Gibson Flatiron manufactured mandolins and banjoes. Erica Shell Manufacturing Company cuts and grinds abalone and other sea shells into small pieces to be used in designs inlayed into mandolins and banjos. Measured wood dust levels ranged from 0.8 to 32mg/cu m with an 8 hour time weighted average (TWA) of 1.2 to 30mg/cu m. Rib construction and assembly, and planing bulk ebony wood had TWA exposures abovemore » the OSHA permissible exposure limit of 5mg/cu m for wood dust. Application of dyes and finishes resulted in low exposures to acetone (67641), toluene (108883), xylene (1330207), and butyl-acetate (123864). No solvent air concentrations were above 10% of their respective PELs. The author concludes that a health hazard existed for exposure to wood dusts. The author recommends the establishment of a respiratory protection program and a hearing conservation program. Emergency egress routes should be marked in the buildings.« less

Visual and ocular changes associated with exposure to two tertiary amines

PubMed Central

Page, E; Cook, C; Hater, M; Mueller, C; Grote, A; Mortimer, V

2003-01-01

Aims: To determine if exposure to dimethylisopropanolamine (DMIPA) and dimethylaminoethanol (DMAE) in a label printing plant was associated with visual disturbances and/or ocular changes. Methods: Questionnaires, eye examinations (visual acuity, contrast sensitivity at 2.5% and 1.25% contrast, slit lamp biomicroscopy, and pachymetry), and industrial hygiene monitoring for DMIPA and DMAE were performed over a two week period. Results: Eighty nine per cent of line workers reported having experienced blurry vision while at work in the past 12 months, compared to 12.5% of prime workers. A total of 108 full shift personal breathing zone (PBZ) air samples for the amines were collected. The mean time weighted average (TWA) concentration of DMIPA was significantly higher in the line division than in the prime division, as was the mean TWA concentration for total amines. The mean TWA concentration of DMAE was higher in the prime division than the line division. Higher levels of total amines were associated with increased risk of reporting blurry vision, halo vision, and blue-grey vision. The risk of corneal opacity rose with increasing exposure to total amines. The prevalence of corneal opacity also increased with increasing concentration of total amines. Median corneal thickness increased with increasing grades of corneal opacity. There was a statistically significant relation between total amine concentration and increased risk of reduced bilateral visual acuity and 2.5% contrast sensitivity. Conclusions: Exposure to tertiary amines was associated with blurry, halo, and blue-grey vision, corneal opacity, and decrements in visual acuity and contrast sensitivity at 2.5% contrast. PMID:12499461

Effectiveness evaluation of existing noise controls in a deep shaft underground mine.

PubMed

Lutz, Eric A; Reed, Rustin J; Turner, Dylan; Littau, Sally R; Lee, Vivien; Hu, Chengcheng

2015-01-01

Noise exposures and hearing loss in the mining industry continue to be a major problem, despite advances in noise control technologies. This study evaluated the effectiveness of engineering, administrative, and personal noise controls using both traditional and in-ear dosimetry by job task, work shift, and five types of earplug. The noise exposures of 22 miners performing deep shaft-sinking tasks were evaluated during 56 rotating shifts in an underground mine. Miners were earplug-insertion trained, earplug fit-tested, and monitored utilizing traditional and in-ear dosimetry. The mean TWA8 noise exposure via traditional dosimetry was 90.1 ± 8.2 dBA, while the mean in-ear TWA8 was 79.6 ± 13.8 dBA. The latter was significantly lower (p < 0.05) than the Mine Safety and Health Administration (MSHA) personal exposure limit (PEL) of 90 dBA. Dosimetry mean TWA8 noise exposures for bench blowing (103.5 ± 0.9 dBA), jumbo drill operation (103.0 ± 0.8 dBA), and mucking tasks (99.6 ± 4.7 dBA) were significantly higher (p < 0.05) than other tasks. For bench blowing, cable pulling, grinding, and jumbo drill operation tasks, the mean in-ear TWA8 was greater than 85 dBA. Those working swing shift had a significantly higher (p < 0.001) mean TWA8 noise exposure (95.4 ± 7.3 dBA) than those working day shift. For percent difference between traditional vs. in-ear dosimetry, there was no significant difference among types of earplug used. Reflective of occupational hearing loss rate trends across the mining industry, this study found that, despite existing engineering and administrative controls, noise exposure levels exceeded regulatory limits, while the addition of personal hearing protection limited excessive exposures.

78 FR 45981 - Occupational Exposure to Noise Standard; Extension of the Office of Management and Budget's (OMB...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-30

..., as part of its continuing effort to reduce paperwork and respondent (i.e., employer) burden, conducts... (the OSH Act) (29 U.S.C. 651 et seq.) authorizes information collection by employers as necessary or... scale (dBA) for an 8-hour time-weighted average (TWA) (action level); take action to reduce noise...

Effects of m-xylene on human equilibrium measured with a quantitative method.

PubMed

Savolainen, K; Linnavuo, M

1979-04-01

Swaying during normal upright posture in 17 young males and the effects of m-xylene exposure on the body sway of six of the 17 has been studied by a quantitative Romberg test, conducted with an equipment consisting of a strain gauge transducer platform and of an electronic unit. The exposures were conducted in a dynamic exposure chamber. The sway of the 17 subjects was larger when their eyes were closed than when they were open (P less than 0.001) indicating the importance of vision in the control of body balance. Exposure to a time-weighted average (TWA) concentration of 100 p.p.m. (4.1 mumol/l) of xylene with 200 p.p.m. (8.2 mumol/l) peaks had no observable effect on the body balance of the six subjects. Exposure to a TWA concentration of 200 p.p.m. of xylene with 400 p.p.m. (16.4 mumol/l) peaks--the corresponding mean concentration of xylene in venous blood being 29.1 +/- 3.2 mumol/l--clearly impaired the body balance of the six subjects. The impairment was most pronounced with the eyes closed (P = 0.016). The results suggest that human equilibrium is rather sensitive to effects of exposure to xylene.

n-hexane polyneuropathy in Japan: a review of n-hexane poisoning and its preventive measures.

PubMed

Takeuchi, Y

1993-07-01

n-Hexane is used in industry as a solvent for adhesive, dry cleaning, and vegetable oil extraction. In 1963, the first case of severe polyneuropathy suspected to be caused by n-hexane was referred to us. Case studies, animal experiments, and field surveys on n-hexane poisoning were conducted, and preventive measures like threshold limit value revision and biological monitoring were also studied. I review a brief history of our investigations on n-hexane poisoning and its preventive measures in Japan. n-Hexane could cause overt polyneuropathy in workers exposed to more than 100 ppm time-weighted average concentrations [TWA]. The present threshold limit value of 40 ppm in Japan is considered low enough to prevent subclinical impairment of peripheral nerve caused by n-hexane. Urinary 2,5-hexanedione could be a good indicator for biological monitoring of n-hexane exposure. About 2.2 mg/liter of 2,5-hexanedione measured by our improved method corresponds to exposure of 40 ppm (TWA) of n-hexane.

Continuing exposure to hexavalent chromium, a known lung carcinogen: an analysis of OSHA compliance inspections, 1990-2000.

PubMed

Lurie, Peter; Wolfe, Sidney M

2002-11-01

Hexavalent chromium is widely recognized to be a lung carcinogen. However, the U.S. Occupational Safety and Health Administration (OSHA) has failed to reduce the permissible exposure limit (PEL), despite having acknowledged in 1994 that the current limit is too high. In 1993, Public Citizen and the Paper, Allied-Industrial, Chemical and Energy Workers International Union (PACE) petitioned to lower the PEL from the current 100 microg/m(3) to 0.5 microg/m(3) as an 8-hr time-weighted average (TWA). To assess industry compliance with the current PEL, and to determine the feasibility of achieving the proposed lower limit of 0.5 microg/m(3), we conducted a secondary data analysis of OSHA's Integrated Management Information System (IMIS) database. This database contains 813 measurements of hexavalent chromium exposure from inspections performed during the years 1990-2000. There was a statistically significant decline in the annual number of measurements over the study period from 127 in 1990 to 67 in 2000 (F = 0.0009; linear regression). The median TWA measurement was 10 microg/m(3) (range: 0.01-13,960 microg/m(3)) and the median ceiling measurement was 40.5 microg/m(3) (range: 0.25-25,000 microg/m(3)). Neither median TWA nor median ceiling exposures (if hexavalent chromium was detected) declined significantly during the study period (F = 0.065 and 0.57, respectively). Overall, 13.7% of TWA measurements were at or below the Public Citizen/PACE proposed standard; 65.0% were between the Public Citizen/PACE proposal and the current OSHA PEL; and 21.3% exceeded the OSHA PEL. Compared to OSHA measurements, state measurements were less likely to detect hexavalent chromium (40.2% vs. 52.1%; P = 0.0007; chi-square) and less likely to issue any citation (9.3% vs. 19.1%; P = 0.0003), including citations for overexposure if the exposure exceeded the PEL (54.8% vs. 78.8%; P = 0.012). U.S. workers continue to be exposed to dangerously high hexavalent chromium levels, but low exposure levels were found in some industries. Further investigations should examine whether state plans provide weaker enforcement than federal OSHA. Copyright 2002 Wiley-Liss, Inc.

Skin exposure to aliphatic polyisocyanates in the auto body repair and refinishing industry: III. A personal exposure algorithm.

PubMed

Liu, Youcheng; Stowe, Meredith H; Bello, Dhimiter; Sparer, Judy; Gore, Rebecca J; Cullen, Mark R; Redlich, Carrie A; Woskie, Susan R

2009-01-01

Isocyanate skin exposure may play an important role in sensitization and the development of isocyanate asthma, but such exposures are frequently intermittent and difficult to assess. Exposure metrics are needed to better estimate isocyanate skin exposures. The goal of this study was to develop a semiquantitative algorithm to estimate personal skin exposures in auto body shop workers using task-based skin exposure data and daily work diaries. The relationship between skin and respiratory exposure metrics was also evaluated. The development and results of respiratory exposure metrics were previously reported. Using the task-based data obtained with a colorimetric skin exposure indicator and a daily work diary, we developed a skin exposure algorithm to estimate a skin exposure index (SEI) for each worker. This algorithm considered the type of personal protective equipment (PPE) used, the percentage of skin area covered by PPE and skin exposures without and underneath the PPE. The SEI was summed across the day (daily SEI) and survey week (weekly average SEI) for each worker, compared among the job title categories and also compared with the respiratory exposure metrics. A total of 893 person-days was calculated for 232 workers (49 painters, 118 technicians and 65 office workers) from 33 auto body shops. The median (10th-90th percentile, maximum) daily SEI was 0 (0-0, 1.0), 0 (0-1.9, 4.8) and 1.6 (0-3.5, 6.1) and weekly average SEI was 0 (0-0.0, 0.7), 0.3 (0-1.6, 4.2) and 1.9 (0.4-3.0, 3.6) for office workers, technicians and painters, respectively, which were significantly different (P < 0.0001). The median (10th-90th percentile, maximum) daily SEI was 0 (0-2.4, 6.1) and weekly average SEI was 0.2 (0-2.3, 4.2) for all workers. A relatively weak positive Spearman correlation was found between daily SEI and time-weighted average (TWA) respiratory exposure metrics (microg NCO m(-3)) (r = 0.380, n = 893, P < 0.0001) and between weekly SEI and TWA respiratory exposure metrics (r = 0.482, n = 232, P < 0.0001). The skin exposure algorithm developed in this study provides task-based personal daily and weekly average skin exposure indices that are adjusted for the use of PPE. These skin exposure indices can be used to assess isocyanate exposure-response relationships.

Measurement of Area and Personal Breathing Zone Concentrations of Diesel Particulate Matter (DPM) during Oil and Gas Extraction Operations, including Hydraulic Fracturing

PubMed Central

Esswein, Eric J.; Alexander-Scott, Marissa; Snawder, John; Breitenstein, Michael

2018-01-01

Diesel engines serve many purposes in modern oil and gas extraction activities. Diesel particulate matter (DPM) emitted from diesel engines is a complex aerosol that may cause adverse health effects depending on exposure dose and duration. This study reports on personal breathing zone (PBZ) and area measurements for DPM (expressed as elemental carbon) during oil and gas extraction operations including drilling, completions (which includes hydraulic fracturing) and servicing work. Researchers at the National Institute for Occupational Safety and Health (NIOSH) collected 104 full-shift air samples (49 PBZ and 55 area) in Colorado, North Dakota, Texas, and New Mexico during a four year period from 2008-2012 The arithmetic mean (AM) of the full shift TWA PBZ samples was 10 μg/m3; measurements ranged from 0.1 to 52 μg/m3. The geometric mean (GM) for the PBZ samples was 7 μg/m3. The AM of the TWA area measurements was 17 μg/m3 and ranged from 0.1 to 68 μg/m3. The GM for the area measurements was 9.5 μg/m3. Differences between the GMs of the PBZ samples and area samples were not statistically different (P>0.05). Neither the Occupational Safety and Health Administration (OSHA), NIOSH, nor the American Conference of Governmental Industrial Hygienists (ACGIH) have established occupational exposure limits (OEL) for DPM. However, the State of California, Department of Health Services lists a time-weighted average (TWA) OEL for DPM as elemental carbon (EC) exposure of 20 μg/m3. Five of 49 (10.2%) PBZ TWA measurements exceeded the 20 μg/m3 EC criterion. These measurements were collected on Sandmover and Transfer Belt (T-belt) Operators, Blender and Chemical Truck Operators, and Water Transfer Operators during hydraulic fracturing operations. Recommendations to minimize DPM exposures include elimination (locating diesel-driven pumps away from well sites), substitution, (use of alternative fuels), engineering controls using advanced emissions controls technologies, administrative controls (configuration of well sites), hazard communication and worker training. PMID:29053946

Measurement of area and personal breathing zone concentrations of diesel particulate matter (DPM) during oil and gas extraction operations, including hydraulic fracturing.

PubMed

Esswein, Eric J; Alexander-Scott, Marissa; Snawder, John; Breitenstein, Michael

2018-01-01

Diesel engines serve many purposes in modern oil and gas extraction activities. Diesel particulate matter (DPM) emitted from diesel engines is a complex aerosol that may cause adverse health effects depending on exposure dose and duration. This study reports on personal breathing zone (PBZ) and area measurements for DPM (expressed as elemental carbon) during oil and gas extraction operations including drilling, completions (which includes hydraulic fracturing), and servicing work. Researchers at the National Institute for Occupational Safety and Health (NIOSH) collected 104 full-shift air samples (49 PBZ and 55 area) in Colorado, North Dakota, Texas, and New Mexico during a four-year period from 2008-2012. The arithmetic mean (AM) of the full shift TWA PBZ samples was 10 µg/m 3 ; measurements ranged from 0.1-52 µg/m 3 . The geometric mean (GM) for the PBZ samples was 7 µg/m 3 . The AM of the TWA area measurements was 17 µg/m 3 and ranged from 0.1-68 µg/m 3 . The GM for the area measurements was 9.5 µg/m 3 . Differences between the GMs of the PBZ samples and area samples were not statistically different (P > 0.05). Neither the Occupational Safety and Health Administration (OSHA), NIOSH, nor the American Conference of Governmental Industrial Hygienists (ACGIH) have established occupational exposure limits (OEL) for DPM. However, the State of California, Department of Health Services lists a time-weighted average (TWA) OEL for DPM as elemental carbon (EC) exposure of 20 µg/m 3 . Five of 49 (10.2%) PBZ TWA measurements exceeded the 20 µg/m 3 EC criterion. These measurements were collected on Sandmover and Transfer Belt (T-belt) Operators, Blender and Chemical Truck Operators, and Water Transfer Operators during hydraulic fracturing operations. Recommendations to minimize DPM exposures include elimination (locating diesel-driven pumps away from well sites), substitution, (use of alternative fuels), engineering controls using advanced emission control technologies, administrative controls (configuration of well sites), hazard communication, and worker training.

Mapping sound intensities by seating position in a university concert band: A risk of hearing loss, temporary threshold shifts, and comparisons with standards of OSHA and NIOSH

NASA Astrophysics Data System (ADS)

Holland, Nicholas Vedder, III

Exposure to loud sounds is one of the leading causes of hearing loss in the United States. The purpose of the current research was to measure the sound pressure levels generated within a university concert band and determine if those levels exceeded permissible sound limits for exposure according to criteria set by the Occupational Safety and Health Administration (OSHA) and the National Institute of Occupational Safety and Health (NIOSH). Time-weighted averages (TWA) were obtained via a dosimeter during six rehearsals for nine members of the ensemble (plus the conductor), who were seated in frontal proximity to "instruments of power" (trumpets, trombones, and percussion; (Backus, 1977). Subjects received audiometer tests prior to and after each rehearsal to determine any temporary threshold shifts (TTS). Single sample t tests were calculated to compare TWA means and the maximum sound intensity exposures set by OSHA and NIOSH. Correlations were calculated between TWAs and TTSs, as well as TTSs and the number of semesters subjects reported being seated in proximity to instruments of power. The TWA-OSHA mean of 90.2 dBA was not significantly greater than the specified OSHA maximum standard of 90.0 dBA (p > .05). The TWA-NIOSH mean of 93.1 dBA was, however, significantly greater than the NIOSH specified maximum standard of 85.0 dBA (p < .05). The correlation between TWAs and TTSs was considered weak (r = .21 for OSHA, r = .20 for NIOSH); the correlation between TTSs and semesters of proximity to instruments of power was also considered weak (r = .13). TWAs cumulatively exceeded both association's sound exposure limits at 11 specified locations (nine subjects and both ears of the conductor) throughout the concert band's rehearsals. In addition, hearing acuity, as determined by TTSs, was substantially affected negatively by the intensities produced in the concert band. The researcher concluded that conductors, as well as their performers, must be aware of possible damaging sound intensities in rehearsals or performances.

An evaluation of retrofit engineering control interventions to reduce perchloroethylene exposures in commercial dry-cleaning shops.

PubMed

Earnest, G Scott; Ewers, Lynda M; Ruder, Avima M; Petersen, Martin R; Kovein, Ronald J

2002-02-01

Real-time monitoring was used to evaluate the ability of engineering control devices retrofitted on two existing dry-cleaning machines to reduce worker exposures to perchloroethylene. In one dry-cleaning shop, a refrigerated condenser was installed on a machine that had a water-cooled condenser to reduce the air temperature, improve vapor recovery, and lower exposures. In a second shop, a carbon adsorber was retrofitted on a machine to adsorb residual perchloroethylene not collected by the existing refrigerated condenser to improve vapor recovery and reduce exposures. Both controls were successful at reducing the perchloroethylene exposures of the dry-cleaning machine operator. Real-time monitoring was performed to evaluate how the engineering controls affected exposures during loading and unloading the dry-cleaning machine, a task generally considered to account for the highest exposures. The real-time monitoring showed that dramatic reductions occurred in exposures during loading and unloading of the dry-cleaning machine due to the engineering controls. Peak operator exposures during loading and unloading were reduced by 60 percent in the shop that had a refrigerated condenser installed on the dry-cleaning machine and 92 percent in the shop that had a carbon adsorber installed. Although loading and unloading exposures were dramatically reduced, drops in full-shift time-weighted average (TWA) exposures were less dramatic. TWA exposures to perchloroethylene, as measured by conventional air sampling, showed smaller reductions in operator exposures of 28 percent or less. Differences between exposure results from real-time and conventional air sampling very likely resulted from other uncontrolled sources of exposure, differences in shop general ventilation before and after the control was installed, relatively small sample sizes, and experimental variability inherent in field research. Although there were some difficulties and complications with installation and maintenance of the engineering controls, this study showed that retrofitting engineering controls may be a feasible option for some dry-cleaning shop owners to reduce worker exposures to perchloroethylene. By installing retrofit controls, a dry-cleaning facility can reduce exposures, in some cases dramatically, and bring operators into compliance with the Occupational Safety and Health Administration (OSHA) peak exposure limit of 300 ppm. Retrofit engineering controls are also likely to enable many dry-cleaning workers to lower their overall personal TWA exposures to perchloroethylene.

Manganese Fractionation Using a Sequential Extraction Method to Evaluate Welders' Shielded Metal Arc Welding Exposures During Construction Projects in Oil Refineries.

PubMed

Hanley, Kevin W; Andrews, Ronnee; Bertke, Steven; Ashley, Kevin

2015-01-01

The National Institute for Occupational Safety and Health has conducted an occupational exposure assessment study of manganese (Mn) in welding fume of construction workers rebuilding tanks, piping, and process equipment at two oil refineries. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. Seventy-two worker-days were monitored for either total or respirable Mn during stick welding and associated activities both within and outside of confined spaces. The samples were analyzed using an experimental method to separate different Mn fractions by valence states based on selective chemical solubility. The full-shift total particulate Mn time-weighted average (TWA) breathing zone concentrations ranged from 0.013-29 for soluble Mn in a mild ammonium acetate solution; from 0.26-250 for Mn(0,2+) in acetic acid; from non-detectable (ND) - 350 for Mn(3+,4+) in hydroxylamine-hydrochloride; and from ND - 39 micrograms per cubic meter (μg/m(3)) for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all Mn fractions in total particulate TWA ranged from 0.52-470 μg/m(3). The range of respirable particulate Mn TWA concentrations were from 0.20-28 for soluble Mn; from 1.4-270 for Mn(0,2+); from 0.49-150 for Mn(3+,4+); from ND - 100 for insoluble Mn; and from 2.0-490 μg/m(3) for Mn (sum of fractions). For all jobs combined, total particulate TWA GM concentrations of the Mn(sum) were 99 (GSD = 3.35) and 8.7 (GSD = 3.54) μg/m(3) for workers inside and outside of confined spaces; respirable Mn also showed much higher levels for welders within confined spaces. Regardless of particle size and confined space work status, Mn(0,2+) fraction was the most abundant followed by Mn(3+,4+) fraction, typically >50% and ∼30-40% of Mn(sum), respectively. Eighteen welders' exposures exceeded the ACGIH Threshold Limit Values for total Mn (100 μg/m(3)) and 25 exceeded the recently adopted respirable Mn TLV (20 μg/m(3)). This study shows that a welding fume exposure control and management program is warranted, especially for welding jobs in confined spaces.

Manganese fractionation using a sequential extraction method to evaluate welders’ shielded metal arc welding exposures during construction projects in oil refineries

PubMed Central

Hanley, Kevin W.; Andrews, Ronnee; Bertke, Steven; Ashley, Kevin

2015-01-01

The National Institute for Occupational Safety and Health (NIOSH) has conducted an occupational exposure assessment study of manganese (Mn) in welding fume of construction workers rebuilding tanks, piping, and process equipment at two oil refineries. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. Seventy-two worker-days were monitored for either total or respirable Mn during stick welding and associated activities both within and outside of confined spaces. The samples were analyzed using an experimental method to separate different Mn fractions by valence states based on selective chemical solubility. The full-shift total particulate Mn time-weighted average (TWA) breathing zone concentrations ranged from 0.013 – 29 for soluble Mn in a mild ammonium acetate solution; from 0.26 – 250 for Mn0,2+ in acetic acid; from non-detectable (ND) – 350 for Mn3+,4+ in hydroxylamine-hydrochloride; and from ND – 39 micrograms per cubic meter (μg/m3) for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all Mn fractions in total particulate TWA ranged from 0.52 to 470 μg/m3. The range of respirable particulate Mn TWA concentrations were from 0.20 – 28 for soluble Mn; from 1.4 – 270 for Mn0,2+; from 0.49 – 150 for Mn3+,4+; from ND – 100 for insoluble Mn; and from 2.0 – 490 μg/m3 for Mn (sum of fractions). For all jobs combined, total particulate TWA GM concentrations of the Mn(sum) were 99 (GSD=3.35) and 8.7 (GSD=3.54) μg/m3 for workers inside and outside of confined spaces; respirable Mn also showed much higher levels for welders within confined spaces. Regardless of particle size and confined space work status, Mn0,2+ fraction was the most abundant followed by Mn3+,4+ fraction, typically >50% and ~30-40% of Mn(sum), respectively. Eighteen welders’ exposures exceeded the ACGIH Threshold Limit Values for total Mn (100 μg/m3) and 25 exceeded the recently adopted respirable Mn TLV (20 μg/m3). This study shows that a welding fume exposure control and management program is warranted, especially for welding jobs in confined spaces. PMID:26011602

T wave alternans during exercise and atrial pacing in humans

NASA Technical Reports Server (NTRS)

Hohnloser, S. H.; Klingenheben, T.; Zabel, M.; Li, Y. G.; Albrecht, P.; Cohen, R. J.

1997-01-01

INTRODUCTION: Evidence is accumulating that microvolt T wave alternans (TWA) is a marker of increased risk for ventricular tachyarrhythmias. Initially, atrial pacing was used to elevate heart rate and elicit TWA. More recently, a noninvasive approach has been developed that elevates heart rate using exercise. METHODS AND RESULTS: In 30 consecutive patients with a history of ventricular tachyarrhythmias, the spectral method was used to detect TWA during both atrial pacing and submaximal exercise testing. The concordance rate for the presence or absence of TWA using the two measurement methods was 84%. There was a patient-specific heart rate threshold for the detection of TWA that averaged 100 +/- 14 beats/min during exercise compared with 97 +/- 9 beats/min during right atrial pacing (P = NS). Beyond this threshold, there was a significant and comparable increase in level of TWA with decreasing pacing cycle length and increasing exercise heart rates. CONCLUSIONS: The present study is the first to demonstrate that microvolt TWA can be assessed reliably and noninvasively during exercise stress. There is a patient-specific heart rate threshold beyond which TWA continues to increase with increasing heart rates. Heart rate thresholds for the onset of TWA measured during atrial pacing and exercise stress were comparable, indicating that heart rate alone appears to be the main factor of determining the onset of TWA during submaximal exercise stress.

Comparisons of discrete and integrative sampling accuracy in estimating pulsed aquatic exposures.

PubMed

Morrison, Shane A; Luttbeg, Barney; Belden, Jason B

2016-11-01

Most current-use pesticides have short half-lives in the water column and thus the most relevant exposure scenarios for many aquatic organisms are pulsed exposures. Quantifying exposure using discrete water samples may not be accurate as few studies are able to sample frequently enough to accurately determine time-weighted average (TWA) concentrations of short aquatic exposures. Integrative sampling methods that continuously sample freely dissolved contaminants over time intervals (such as integrative passive samplers) have been demonstrated to be a promising measurement technique. We conducted several modeling scenarios to test the assumption that integrative methods may require many less samples for accurate estimation of peak 96-h TWA concentrations. We compared the accuracies of discrete point samples and integrative samples while varying sampling frequencies and a range of contaminant water half-lives (t 50  = 0.5, 2, and 8 d). Differences the predictive accuracy of discrete point samples and integrative samples were greatest at low sampling frequencies. For example, when the half-life was 0.5 d, discrete point samples required 7 sampling events to ensure median values > 50% and no sampling events reporting highly inaccurate results (defined as < 10% of the true 96-h TWA). Across all water half-lives investigated, integrative sampling only required two samples to prevent highly inaccurate results and measurements resulting in median values > 50% of the true concentration. Regardless, the need for integrative sampling diminished as water half-life increased. For an 8-d water half-life, two discrete samples produced accurate estimates and median values greater than those obtained for two integrative samples. Overall, integrative methods are the more accurate method for monitoring contaminants with short water half-lives due to reduced frequency of extreme values, especially with uncertainties around the timing of pulsed events. However, the acceptability of discrete sampling methods for providing accurate concentration measurements increases with increasing aquatic half-lives. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Study of the effect of occupational exposure to glyphosate on hepatorenal function].

PubMed

Zhang, F; Pan, L P; Ding, E M; Ge, Q J; Zhang, Z H; Xu, J N; Zhang, L; Zhu, B L

2017-07-06

Objective: To explore the effect of occupational exposure to glyphosate on hepatorenal function. Methods: 526 workers who were occupationally exposed to glyphosate from 5 glyphosate-producing factories were selected as cases; and another 442 administrative staffs who were not exposed to glyphosate were selected as controls from April to November, 2014. All the subjects accepted occupational health examination. The concentration level of glyphosate in the air of workshop was detected and the time weighted average concentration (TWA) was calculated. And analyze the difference of hepatorenal fuction between case group and control group. Result: The age of the subjects in the case and control groups were separately (35.6±10.3), (34.3±9.7) years old, with the length of working for (6.5±5.7), (7.7±6.8) years. The TWA of glyphosate in the case group was between <0.03-48.91 mg/m(3), with the geometric mean at 3.78 mg/m(3). The overall rates of abnormal hepatic and renal function in the case group were 14.4% (76 cases) and 16.2% (85 cases), respectively; while those were 5.0% (22 cases) and 4.8% (21 cases), respectively in control group, and the difference showed statistical significance ( P <0.05). When TWA reached <0.03-6.00 mg/m(3), the difference of hepatorenal fuction between case group and control group showed statistical significance, and the rates of abnormal hepatic and renal function was 8.0% (36/447) and 9.8% (44/447) respectively in case group. When cumulative exposure level reached <1.56-68.64 g, the difference of hepatorenal fuction between case group and control group showed statistical significance, and the rates increased to 9.2% (37/404) and 10.4% (42/404) respectively in group of cases. Conclusion: Glyphosate can affect the hepatic and renal function among occupational exposure population, and there was an association between the effect and the exposure dose.

Derivation of an occupational exposure limit for an inhalation analgesic methoxyflurane (Penthrox(®)).

PubMed

Frangos, John; Mikkonen, Antti; Down, Christin

2016-10-01

Methoxyflurane (MOF) a haloether, is an inhalation analgesic agent for emergency relief of pain by self administration in conscious patients with trauma and associated pain. It is administered under supervision of personnel trained in its use. As a consequence of supervised use, intermittent occupational exposure can occur. An occupational exposure limit has not been established for methoxyflurane. Human clinical and toxicity data have been reviewed and used to derive an occupational exposure limit (referred to as a maximum exposure level, MEL) according to modern principles. The data set for methoxyflurane is complex given its historical use as anaesthetic. Distinguishing clinical investigations of adverse health effects following high and prolonged exposure during anaesthesia to assess relatively low and intermittent exposure during occupational exposure requires an evidence based approach to the toxicity assessment and determination of a critical effect and point of departure. The principal target organs are the kidney and the central nervous system and there have been rare reports of hepatotoxicity, too. Methoxyflurane is not genotoxic based on in vitro bacterial mutation and in vivo micronucleus tests and it is not classifiable (IARC) as a carcinogenic hazard to humans. The critical effect chosen for development of a MEL is kidney toxicity. The point of departure (POD) was derived from the concentration response relationship for kidney toxicity using the benchmark dose method. A MEL of 15 ppm (expressed as an 8 h time weighted average (TWA)) was derived. The derived MEL is at least 50 times higher than the mean observed TWA (0.23 ppm) for ambulance workers and medical staff involved in supervising use of Penthrox. In typical treatment environments (ambulances and treatment rooms) that meet ventilation requirements the derived MEL is at least 10 times higher than the modelled TWA (1.5 ppm or less) and the estimated short term peak concentrations are within the MEL. The odour threshold for MOF of 0.13-0.19 ppm indicates that the odour is detectable well below the MEL. Given the above considerations the proposed MEL is health protective. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Cardiovascular risk in operators under radiofrequency electromagnetic radiation.

PubMed

Vangelova, Katia; Deyanov, Christo; Israel, Mishel

2006-03-01

The aim of the study was to assess the long-term effects of radiofrequency electromagnetic radiation (EMR) on the cardiovascular system. Two groups of exposed operators (49 broadcasting (BC) station and 61 TV station operators) and a control group of 110 radiorelay station operators, matched by sex and age, with similar job characteristics except for the radiofrequency EMR were studied. The EMR exposure was assessed and the time-weighted average (TWA) was calculated. The cardiovascular risk factors arterial pressure, lipid profile, body mass index, waist/hip ratio, smoking, and family history of cardiovascular disease were followed. The systolic and diastolic blood pressure (SBP and DBP), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were significantly higher in the two exposed groups. It was found that the radiofrequency EMR exposure was associated with greater chance of becoming hypertensive and dyslipidemic. The stepwise multiple regression equations showed that the SBP and TWA predicted the high TC and high LDL-C, while the TC, age and abdominal obesity were predictors for high SBP and DBP. In conclusion, our data show that the radiofrequency EMR contributes to adverse effects on the cardiovascular system.

Formaldehyde: a comparative evaluation of four monitoring methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coyne, L.B.; Cook, R.E.; Mann, J.R.

1985-10-01

The performances of four formaldehyde monitoring devices were compared in a series of laboratory and field experiments. The devices evaluated included the DuPont C-60 formaldehyde badge, the SKC impregnated charcoal tube, an impinger/polarographic method and the MDA Lion formaldemeter. The major evaluation parameters included: concentration range, effects of humidity, sample storage, air velocity, accuracy, precision, interferences from methanol, styrene, 1,3-butadiene, sulfur dioxide and dimethylamine. Based on favorable performances in the laboratory and field, each device was useful for monitoring formaldehyde in the industrial work environment; however, these devices were not evaluated for residential exposure assessment. The impinger/polarographic method had amore » sensitivity of 0.06 ppm, based on a 20-liter air sample volume, and accurately determined the short-term excursion limit (STEL). It was useful for area monitoring but was not very practical for time-weighted average (TWA) personal monitoring measurements. The DuPont badge had a sensitivity of 2.8 ppm-hr and accurately and simply determined TWA exposures. It was not sensitive enough to measure STEL exposures, however, and positive interferences resulted if 1,3-butadiene was present. The SKC impregnated charcoal tube measured both TWA and STEL concentrations and had a sensitivity of 0.06 ppm based on a 25-liter air sample volume. Lightweight and simple to use, the MDA Lion formaldemeter had a sensitivity of 0.2 ppm. It had the advantage of giving an instantaneous reading in the field; however, it must be used with caution because it responded to many interferences. The method of choice depended on the type of sampling required, field conditions encountered during sampling and an understanding of the limitations of each monitoring device.« less

Benzene Exposures and Risk Potential for Vehicle Mechanics from Gasoline and Petroleum-Derived Products.

PubMed

Williams, Pamela R D; Mani, Ashutosh

2015-01-01

Benzene exposures among vehicle mechanics in the United States and abroad were characterized using available data from published and unpublished studies. In the United States, the time-weighted-average (TWA) airborne concentration of benzene for vehicle mechanics averaged 0.01-0.05 ppm since at least the late 1970s, with maximal TWA concentrations ranging from 0.03 to 0.38 ppm. Benzene exposures were notably lower in the summer than winter and in the Southwest compared to other geographic regions, but significantly higher during known gasoline-related tasks such as draining a gas tank or changing a fuel pump or fuel filter. Measured airborne concentrations of benzene were also generally greater for vehicle mechanics in other countries, likely due to the higher benzene content of gasoline and other factors. Short-term airborne concentrations of benzene frequently exceeded 1 ppm during gasoline-related tasks, but remained below 0.2 ppm for tasks involving other petroleum-derived products such as carburetor and brake cleaner or parts washer solvent. Application of a two-zone mathematical model using reasonable input values from the literature yielded predicted task-based benzene concentrations during gasoline and aerosol spray cleaner scenarios similar to those measured for vehicle mechanics during these types of tasks. When evaluated using appropriate biomarkers, dermal exposures were found to contribute little to total benzene exposures for this occupational group. Available data suggest that vehicle mechanics have not experienced significant exposures to benzene in the workplace, except perhaps during short-duration gasoline-related tasks, and full-shift benzene exposures have remained well below current and contemporaneous occupational exposure limits. These findings are consistent with epidemiology studies of vehicle mechanics, which have not demonstrated an increased risk of benzene-induced health effects in this cohort of workers. Data and information presented here may be used to assess past, current, or future exposures and risks to benzene for vehicle mechanics who may be exposed to gasoline or other petroleum-derived products.

Permeation Resistance of Personal Protective Equipment Materials to Monomethyhydrazine

NASA Technical Reports Server (NTRS)

Waller, J. M.; Williams, J. H.

1997-01-01

Permeation resistance was determined by measuring the breakthrough time and time-averaged vapor transmission rate of monomethylhydrazine (MMH) through two types of personal protective equipment (PPE). The two types of PPE evaluated were the totally encapsulating ILC Dover Chemturion Model 1212 chemical protective suit with accessories, and the FabOhio polyvinyl chloride (PVC) splash garment. Two exposure scenarios were simulated: (1) a saturated vapor exposure for 2 hours (h), and (2) a brief MMH 'splash' followed by a 2-h saturated vapor exposure. Time-averaged MMH concentrations inside the totally-encapsulating suit were calculated by summation of the area-weighted contributions made by each suit component. Results show that the totally encapsulating suit provides adequate protection at the new 10 ppb Threshold Limit Value Time-Weighted Average (TLV-TWA). The permeation resistance of the PVC splash garment to MMH was poorer than any of the totally encapsulating suit materials tested. Breakthrough occurred soon after initial vapor or 'splash' exposure.

Factors influencing dust exposure: finishing activities in drywall construction.

PubMed

Simmons, Catherine E; Jones, Rachael M; Boelter, Fred W

2011-05-01

Sanding drywall joint compound is a dusty construction activity. We studied potential factors influencing exposure to respirable and total dust for sanders and bystanders in the area of drywall joint compound finishing in 17 test events within a room-scale isolation chamber. We found the air change rate to be negatively correlated with dust C(twa) both in the sander's personal breathing zone and surrounding area. We could not conclude that sanding tool type systematically influences dust C(twa), but the use of 80-grit abrasive was associated with the highest dust C(twa). We found respirable dusts were uniformly dispersed 1-8.2 m from sanding activities at a fixed location. As anticipated, both respirable and total dust C(twa) in the sander's personal breathing zone are higher than in the surrounding area. The respirable fraction of the total dust mass C(twa) was greater in the surrounding area than in the sander's personal breathing zone. Respirable dust concentrations measured in real time increased over the duration of sanding, exhibiting a temporal trend that is similar to that predicted by the well-mixed box model with contaminant removal by mechanical ventilation only, and continuous emission. Dust concentrations returned to pre-activity (background) levels 2-4 hr after cessation of the sanding activity.

New Parallaxes and a Convergence Analysis for the TW Hya Association

NASA Astrophysics Data System (ADS)

Donaldson, J. K.; Weinberger, A. J.; Gagné, J.; Faherty, J. K.; Boss, A. P.; Keiser, S. A.

2016-12-01

The TW Hya Association (TWA) is a nearby stellar association with an age of ˜5-10 Myr. This is an important age for studying the late stages of star and planet formation. We measure the parallaxes of 14 candidate members of TWA. That brings to 38 the total number of individual stars with fully measured kinematics, I.e., proper motion, radial velocity, and parallax, to describe their motions through the Galaxy. We analyze these kinematics to search for convergence to a smaller volume in the past, but we find that the association is never much more compact than it is at present. We show that it is difficult to measure traceback ages for associations such as TWA that have expected velocity dispersions of 1-2 km s-1 with typical measurement uncertainties. We also use our stellar distances and pre-main-sequence evolutionary tracks to find the average age of the association of 7.9 ± 1.0 Myr. Additionally, our parallax measurement of TWA 32 indicates that it should be considered a bona fide member of TWA. Two new candidate members have high membership probabilities, and we assign them TWA numbers: TWA 45 for 2MASS J11592786-4510192 and TWA 46 for 2MASS J12354615-4115531.

Assessing human exposure to power-frequency electric and magnetic fields.

PubMed Central

Kaune, W T

1993-01-01

This paper reviews published literature and current problems relating to the assessment of occupational and residential human exposures to power-frequency electric and magnetic fields. Available occupational exposure data suggest that the class of job titles known as electrical workers may be an effective surrogate for time-weighted-average (TWA) magnetic-field (but not electric-field) exposure. Current research in occupational-exposure assessment is directed to the construction of job-exposure matrices based on electric- and magnetic-field measurements and estimates of worker exposures to chemicals and other factors of interest. Recent work has identified five principal sources of residential magnetic fields: electric power transmission lines, electric power distribution lines, ground currents, home wiring, and home appliances. Existing residential-exposure assessments have used one or more of the following techniques: questionnaires, wiring configuration coding, theoretical field calculations, spot electric- and magnetic-field measurements, fixed-site magnetic-field recordings, personal- exposure measurements, and geomagnetic-field measurements. Available normal-power magnetic-field data for residences differ substantially between studies. It is not known if these differences are due to geographical differences, differences in measurement protocols, or instrumentation differences. Wiring codes and measured magnetic fields (but not electric fields) are associated weakly. Available data suggest, but are far from proving, that spot measurements may be more effective than wire codes as predictors of long-term historical magnetic-field exposure. Two studies find that away-from-home TWA magnetic-field exposures are less variable than at-home exposures. The importance of home appliances as contributors to total residential magnetic-field exposure is not known at this time. It also is not known what characteristics (if any) of residential electric and magnetic fields are determinants of human health effects. PMID:8206021

N-Acetyl-S-(n-Propyl)-L-Cysteine in Urine from Workers Exposed to 1-Bromopropane in Foam Cushion Spray Adhesives

PubMed Central

Hanley, Kevin W.; Petersen, Martin R.; Cheever, Kenneth L.; Luo, Lian

2009-01-01

1-Bromopropane (1-BP) has been marketed as an alternative for ozone depleting and other solvents; it is used in aerosol products, adhesives, metal, precision, and electronics cleaning solvents. Mechanisms of toxicity of 1-BP are not fully understood, but it may be a neurological and reproductive toxicant. Sparse exposure information prompted this study using 1-BP air sampling and urinary metabolites. Mercapturic acid conjugates are excreted in urine from 1-BP metabolism involving debromination. Research objectives were to evaluate the utility of urinary N-acetyl-S-(n-propyl)-L-cysteine (AcPrCys) for assessing exposure to 1-BP and compare it to urinary bromide [Br(−)] previously reported for these workers. Forty-eight-hour urine specimens were obtained from 30 workers at two factories where 1-BP spray adhesives were used to construct polyurethane foam seat cushions. Urine specimens were also obtained from 21 unexposed control subjects. All the workers' urine was collected into composite samples representing three time intervals: at work, after work but before bedtime, and upon awakening. Time-weighted average (TWA) geometric mean breathing zone concentrations were 92.4 and 10.5 p.p.m. for spraying and non-spraying jobs, respectively. Urinary AcPrCys showed the same trend as TWA exposures to 1-BP: higher levels were observed for sprayers. Associations of AcPrCys concentrations, adjusted for creatinine, with 1-BP TWA exposure were statistically significant for both sprayers (P < 0.05) and non-sprayers (P < 0.01). Spearman correlation coefficients for AcPrCys and Br(−) analyses determined from the same urine specimens were highly correlated (P < 0.0001). This study confirms that urinary AcPrCys is an important 1-BP metabolite and an effective biomarker for highly exposed foam cushion workers. PMID:19706636

Task-based exposure assessment of nanoparticles in the workplace

NASA Astrophysics Data System (ADS)

Ham, Seunghon; Yoon, Chungsik; Lee, Euiseung; Lee, Kiyoung; Park, Donguk; Chung, Eunkyo; Kim, Pilje; Lee, Byoungcheun

2012-09-01

Although task-based sampling is, theoretically, a plausible approach to the assessment of nanoparticle exposure, few studies using this type of sampling have been published. This study characterized and compared task-based nanoparticle exposure profiles for engineered nanoparticle manufacturing workplaces (ENMW) and workplaces that generated welding fumes containing incidental nanoparticles. Two ENMW and two welding workplaces were selected for exposure assessments. Real-time devices were utilized to characterize the concentration profiles and size distributions of airborne nanoparticles. Filter-based sampling was performed to measure time-weighted average (TWA) concentrations, and off-line analysis was performed using an electron microscope. Workplace tasks were recorded by researchers to determine the concentration profiles associated with particular tasks/events. This study demonstrated that exposure profiles differ greatly in terms of concentrations and size distributions according to the task performed. The size distributions recorded during tasks were different from both those recorded during periods with no activity and from the background. The airborne concentration profiles of the nanoparticles varied according to not only the type of workplace but also the concentration metrics. The concentrations measured by surface area and the number concentrations measured by condensation particle counter, particulate matter 1.0, and TWA mass concentrations all showed a similar pattern, whereas the number concentrations measured by scanning mobility particle sizer indicated that the welding fume concentrations at one of the welding workplaces were unexpectedly higher than were those at workplaces that were engineering nanoparticles. This study suggests that a task-based exposure assessment can provide useful information regarding the exposure profiles of nanoparticles and can therefore be used as an exposure assessment tool.

Exposures to 1,6-hexamethylene diisocyanate during polyurethane spray painting in the U.S. Air Force.

PubMed

Carlton, G N; England, E C

2000-09-01

1,6-Hexamethylene diisocyanate (HDI) exposures were measured during polyurethane enamel spray painting at four Air Force bases. Breathing zone samples were collected for HDI monomer and polyisocyanates (oligomers) using three sampling methods: NIOSH Method 5521, the Iso-Chek sampler, and the total aerosol mass method (TAMM). Exposures to HDI monomer are low when compared to current occupational exposure limits; the highest 8-hr time-weighted average (TWA) exposure found was 3.5 micrograms/m3, below the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 34 micrograms/m3. HDI oligomer levels were higher; mean task exposures indicated by either the Iso-Chek sampler or TAMM are above the Oregon ceiling limit of 1 mg/m3. Eight-hour TWA exposures, however, were much lower, with only one exceeding the Oregon standard of 0.5 mg/m3. Poor worker practices commonly observed during this study included: standing in downwind positions so paint overspray passed through breathing zones; spraying toward other painters; and using excessive paint spray gun air cap pressures. Workers should stand in upwind orientation relative to the aircraft being painted, causing overspray to move away from the painter's breathing zone; adjust their position to prevent spraying other painters or limit paint application to one worker at a time; and use air cap pressure gauges prior to spraying to limit spray gun air cap pressures and reduce paint overspray generation rates. These improved techniques will result in reduced worker exposures to isocyanates.

Correlation between urinary methoxyacetic acid and exposure of ethylene glycol dimethyl ether in a lithium battery plant.

PubMed

Yokota, Kozo; Ueno, Hiroshi; Ikeda, Naoko; Johyama, Yasushi; Michitsuji, Hiromi; Yamada, Seiji

2007-10-01

To examine the correlation between airborne ethylene glycol dimethyl ether (EGdiME) exposures and the urinary methoxyacetic acid (MAA) and to approach the issue of a permissible exposure limit for EGdiME. The survey was conducted on Thursday. Workers occupationally exposed to EGdiME, as well as nonexposed controls, were studied in combination with one of the authors, who was coincidentally exposed to EGdiME while carrying out the study. Air levels of EGdiME were determined by personal sampling on passive gas tubes. Urine was collected from nine control subjects and ten workers immediately before and after the shift, and from one of the authors at intervals during 12 h. The analyses of EGdiME in air and MAA in urine were performed by gas chromatography with flame ionization detection. The time-weighted average (TWA) air levels of EGdiME ranged from 0.7 to 10.5 ppm during 8 h work shifts. The urinary levels of MAA in one of the authors increased continuously during exposure and after the end of exposure. The levels of urinary MAA in the exposed workers were significantly higher than those in the control subjects. On the other hand, the postshift values were higher than the preshift values in the exposed workers, but the difference was not significant. A linear correlation was found between the TWA air levels of EGdiME and creatinine-adjusted MAA levels in urine collected at the end of the shift (r = 0.933; P < 0.0001). According to our equation, a linear extrapolation to the biological limit value recommended by Shih et al. (1999) of 40 mg MAA/g crea indicated an average inhalation exposure to EGdiME over the workweek of 12 ppm. These results indicate that the determination of MAA in urine is suitable for use in the biological monitoring of EGdiME exposure.

Comparison of occupational exposure to carbon disulphide in a viscose rayon factory before and after technical adjustments.

PubMed

Bulat, Petar; Daemen, Edgard; Van Risseghem, Marleen; De Bacquer, Dirk; Tan, Xiaodong; Braeckman, Lutgart; Vanhoorne, Michel

2002-01-01

The objective of this follow-up study was to verify the efficacy of the technical adjustments gradually introduced in departments of a viscose rayon factory from 1989 onward. Personal exposure to carbon disulphide was assessed by means of personal monitoring through active sampling. Six job titles in three departments of the factory were sampled. Geometric means were calculated and used as estimates of time-weighted average (TWA) concentrations. The results from the present study were compared with similar measurements from a previous study in the same factory. Due to organizational changes, only three job titles (spinner, first spinner, and viscose preparator) could be compared directly. Two new job titles were identified, although tasks performed in these two job titles already existed. The measurements from one job title could not be compared, due to a substantial reorganization and automation of the tasks carried out in the department. The comparison before and after technical improvements shows that personal exposure of spinner and first spinner has been substantially reduced. Even the geometric means of measurements outside the fresh air mask are below the TWA-TLV (Threshold Limit Value). Despite the difficulties in comparing the results from the two studies, it is concluded that the technical measures reduced up to tenfold personal exposure to carbon disulphide and personal protection reduced it further by a factor two.

Carbon Nanotube and Nanofiber Exposure Assessments: An Analysis of 14 Site Visits.

PubMed

Dahm, Matthew M; Schubauer-Berigan, Mary K; Evans, Douglas E; Birch, M Eileen; Fernback, Joseph E; Deddens, James A

2015-07-01

Recent evidence has suggested the potential for wide-ranging health effects that could result from exposure to carbon nanotubes (CNT) and carbon nanofibers (CNF). In response, the National Institute for Occupational Safety and Health (NIOSH) set a recommended exposure limit (REL) for CNT and CNF: 1 µg m(-3) as an 8-h time weighted average (TWA) of elemental carbon (EC) for the respirable size fraction. The purpose of this study was to conduct an industrywide exposure assessment among US CNT and CNF manufacturers and users. Fourteen total sites were visited to assess exposures to CNT (13 sites) and CNF (1 site). Personal breathing zone (PBZ) and area samples were collected for both the inhalable and respirable mass concentration of EC, using NIOSH Method 5040. Inhalable PBZ samples were collected at nine sites while at the remaining five sites both respirable and inhalable PBZ samples were collected side-by-side. Transmission electron microscopy (TEM) PBZ and area samples were also collected at the inhalable size fraction and analyzed to quantify and size CNT and CNF agglomerate and fibrous exposures. Respirable EC PBZ concentrations ranged from 0.02 to 2.94 µg m(-3) with a geometric mean (GM) of 0.34 µg m(-3) and an 8-h TWA of 0.16 µg m(-3). PBZ samples at the inhalable size fraction for EC ranged from 0.01 to 79.57 µg m(-3) with a GM of 1.21 µg m(-3). PBZ samples analyzed by TEM showed concentrations ranging from 0.0001 to 1.613 CNT or CNF-structures per cm(3) with a GM of 0.008 and an 8-h TWA concentration of 0.003. The most common CNT structure sizes were found to be larger agglomerates in the 2-5 µm range as well as agglomerates >5 µm. A statistically significant correlation was observed between the inhalable samples for the mass of EC and structure counts by TEM (Spearman ρ = 0.39, P < 0.0001). Overall, EC PBZ and area TWA samples were below the NIOSH REL (96% were <1 μg m(-3) at the respirable size fraction), while 30% of the inhalable PBZ EC samples were found to be >1 μg m(-3). Until more information is known about health effects associated with larger agglomerates, it seems prudent to assess worker exposure to airborne CNT and CNF materials by monitoring EC at both the respirable and inhalable size fractions. Concurrent TEM samples should be collected to confirm the presence of CNT and CNF. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2015.

Estimation of personal exposure to asbestos of brake repair workers.

PubMed

Cely-García, María Fernanda; Curriero, Frank C; Sánchez-Silva, Mauricio; Breysse, Patrick N; Giraldo, Margarita; Méndez, Lorena; Torres-Duque, Carlos; Durán, Mauricio; González-García, Mauricio; Parada, Patricia; Ramos-Bonilla, Juan Pablo

2017-07-01

Exposure assessments are key tools to conduct epidemiological studies. Since 2010, 28 riveters from 18 brake repair shops with different characteristics and workloads were sampled for asbestos exposure in Bogotá, Colombia. Short-term personal samples collected during manipulation activities of brake products, and personal samples collected during non-manipulation activities were used to calculate 103 8-h TWA PCM-equivalent personal asbestos concentrations. The aims of this study are to identify exposure determinant variables associated with the 8-h TWA personal asbestos concentrations among brake mechanics, and propose different models to estimate potential asbestos exposure of brake mechanics in an 8-h work-shift. Longitudinal-based multivariate linear regression models were used to determine the association between personal asbestos concentrations in a work-shift with different variables related to work tasks and workload of the mechanics, and some characteristics of the shops. Monte Carlo simulations were used to estimate the 8-h TWA PCM-Eq personal asbestos concentration in work-shifts that had manipulations of brake products or cleaning activities of the manipulation area, using the results of the sampling campaigns. The simulations proposed could be applied for both current and retrospective studies to determine personal asbestos exposures of brake mechanics, without the need of sampling campaigns or historical data of air asbestos concentrations.

Pulsed Accretion in the T Tauri Binary TWA 3A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tofflemire, Benjamin M.; Mathieu, Robert D.; Herczeg, Gregory J.

TWA 3A is the most recent addition to a small group of young binary systems that both actively accrete from a circumbinary disk and have spectroscopic orbital solutions. As such, it provides a unique opportunity to test binary accretion theory in a well-constrained setting. To examine TWA 3A’s time-variable accretion behavior, we have conducted a two-year, optical photometric monitoring campaign, obtaining dense orbital phase coverage (∼20 observations per orbit) for ∼15 orbital periods. From U -band measurements we derive the time-dependent binary mass accretion rate, finding bursts of accretion near each periastron passage. On average, these enhanced accretion events evolvemore » over orbital phases 0.85 to 1.05, reaching their peak at periastron. The specific accretion rate increases above the quiescent value by a factor of ∼4 on average but the peak can be as high as an order of magnitude in a given orbit. The phase dependence and amplitude of TWA 3A accretion is in good agreement with numerical simulations of binary accretion with similar orbital parameters. In these simulations, periastron accretion bursts are fueled by periodic streams of material from the circumbinary disk that are driven by the binary orbit. We find that TWA 3A’s average accretion behavior is remarkably similar to DQ Tau, another T Tauri binary with similar orbital parameters, but with significantly less variability from orbit to orbit. This is only the second clear case of orbital-phase-dependent accretion in a T Tauri binary.« less

A control technology evaluation of state-of-the-art, perchloroethylene dry-cleaning machines.

PubMed

Earnest, G Scott

2002-05-01

NIOSH researchers evaluated the ability of fifth-generation dry-cleaning machines to control occupational exposure to perchloroethylene (PERC). Use of these machines is mandated in some countries; however, less than 1 percent of all U.S. shops have them. A study was conducted at a U.S. dry-cleaning shop where two fifth-generation machines were used. Both machines had a refrigerated condenser as a primary control and a carbon adsorber as a secondary control to recover PERC vapors during the dry cycle. These machines were designed to lower the PERC concentration in the cylinder at the end of the dry cycle to below 290 ppm. A single-beam infrared photometer continuously monitors the PERC concentration in the machine cylinder, and a door interlock prevents opening until the concentration is below 290 ppm. Personal breathing zone air samples were measured for the machine operator and presser. The operator had time-weighted average (TWA) PERC exposures that were less than 2 ppm. Highest exposures occurred during loading and unloading the machine and when performing routine machine maintenance. All presser samples were below the limit of detection. Real-time video exposure monitoring showed that the operator had peak exposures near 160 ppm during loading and unloading the machine (below the OSHA maximum of 300 ppm). This exposure (160 ppm) is an order of magnitude lower than exposures with more traditional machines that are widely used in the United States. The evaluated machines were very effective at reducing TWA PERC exposures as well as peak exposures that occur during machine loading and unloading. State-of-the-art dry-cleaning machines equipped with refrigerated condensers, carbon adsorbers, drum monitors, and door interlocks can provide substantially better protection than more traditional machines that are widely used in the United States.

T-wave alternans, air pollution and traffic in high-risk subjects.

PubMed

Zanobetti, Antonella; Stone, Peter H; Speizer, Frank E; Schwartz, Joel D; Coull, Brent A; Suh, Helen H; Nearing, Bruce D; Mittleman, Murray A; Verrier, Richard L; Gold, Diane R

2009-09-01

Particulate pollution has been linked to risk for cardiac death; possible mechanisms include pollution-related increases in cardiac electrical instability. T-wave alternans (TWA) is a marker of cardiac electrical instability measured as differences in the magnitude between adjacent T waves. In a repeated-measures study of 48 patients aged 43 to 75 years, associations of ambient and home indoor particulate pollution, including black carbon (BC) and reports of traffic exposure, with changes in 0.5-hourly maximum TWA (TWA-MAX), measured by 24-hour Holter electrocardiographic monitoring, were investigated. Each patient was observed up to 4 times within 1 year after percutaneous intervention for myocardial infarction, acute coronary syndromes without infarction, or stable coronary artery disease, for a total of 5,830 0.5-hour observations. Diary data for each 0.5-hour period defined whether a patient was home or not home, or in traffic. Increases in TWA-MAX were independently associated with the previous 2-hour mean ambient BC (2.1%, 95% confidence interval 0.9% to 3.3%) and with being in traffic in the previous 2 hours (6.1%, 95% confidence interval 3.4% to 8.8%). When subjects were home, indoor home BC effects were largest and most precise; when subjects were away from home, ambient central site BC effects were strongest. Increases in pollution increased the odds of TWA-MAX > or =75th percentile (odds ratio 1.4, 95% confidence interval 1.2 to 1.6 for a 1 microg/m(3) increase in 6-hour mean BC). In conclusion, after hospitalization for coronary artery disease, being in traffic and short-term ambient or indoor BC exposure increased TWA, a marker of cardiac electrical instability.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saenz, Juan A.; Chen, Qingshan; Ringler, Todd

Recent work has shown that taking the thickness-weighted average (TWA) of the Boussinesq equations in buoyancy coordinates results in exact equations governing the prognostic residual mean flow where eddy–mean flow interactions appear in the horizontal momentum equations as the divergence of the Eliassen–Palm flux tensor (EPFT). It has been proposed that, given the mathematical tractability of the TWA equations, the physical interpretation of the EPFT, and its relation to potential vorticity fluxes, the TWA is an appropriate framework for modeling ocean circulation with parameterized eddies. The authors test the feasibility of this proposition and investigate the connections between the TWAmore » framework and the conventional framework used in models, where Eulerian mean flow prognostic variables are solved for. Using the TWA framework as a starting point, this study explores the well-known connections between vertical transfer of horizontal momentum by eddy form drag and eddy overturning by the bolus velocity, used by Greatbatch and Lamb and Gent and McWilliams to parameterize eddies. After implementing the TWA framework in an ocean general circulation model, we verify our analysis by comparing the flows in an idealized Southern Ocean configuration simulated using the TWA and conventional frameworks with the same mesoscale eddy parameterization.« less

Coke workers' exposure to volatile organic compounds in northern China: a case study in Shanxi Province.

PubMed

He, Qiusheng; Yan, Yulong; Zhang, Yanli; Wang, Xinming; Wang, Yuhang

2015-06-01

China is the largest coke producer and exporter in the world, and it has been a major concern that large populations of coke workers are exposed to the associated air pollutants such as volatile organic compounds (VOCs). This study aimed to preliminarily quantify the potential exposure to VOCs emitted from two representative coking plants and assess the potential health risks. Air samples from various stages of coking were collected from the topside of coke ovens and various plant areas and then analyzed for benzene, toluene, ethylbenzene, and xylene (BTEX). The time-weighted average (TWA) concentrations were used to quantify the coke oven emission (COE). The TWA concentrations for benzene were 705.6 and 290.4 μg m(-3) in plant A and plant B, respectively, which showed a higher exposure level than those reported in other countries. COE varied on the topside of coke ovens during charging and pushing processes, from 268.3 to 1197.7 μg m(-3) in plant A and 85.4-489.7 μg m(-3) in plant B. Our results indicate that benzene exposure from the diffusion of tar distillation also exerts significant health risks and thus should also be concerned. Charging and pushing activities accounted for nearly 70 % of benzene dose at the topside, and the benzene exposure risks to the coke oven workers in China were higher than those reported by US EPA. Compared to the reported emission sources, the weight-based ratios of average benzene to toluene, ethylbenzene, and xylene in different COE air samples showed unique characteristic profiles. Based on the B/T ratios from this work and from literatures on several major cities in northern China, it was evident that COE contributes significantly to the severe pollution of VOCs in the air of northern China. Future more rigorous studies are warranted to characterize VOC emission profiles in the stack gas of the coking processes in China.

A Comparison of "Total Dust" and Inhalable Personal Sampling for Beryllium Exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, Colleen M.

2012-05-09

In 2009, the American Conference of Governmental Industrial Hygienists (ACGIH) reduced the Beryllium (Be) 8-hr Time Weighted Average Threshold Limit Value (TLV-TWA) from 2.0 μg/m 3 to 0.05 μg/m 3 with an inhalable 'I' designation in accordance with ACGIH's particle size-selective criterion for inhalable mass. Currently, per the Department of Energy (DOE) requirements, the Lawrence Livermore National Laboratory (LLNL) is following the Occupational Health and Safety Administration (OSHA) Permissible Exposure Limit (PEL) of 2.0 μg/m 3 as an 8-hr TWA, which is also the 2005 ACGIH TLV-TWA, and an Action Level (AL) of 0.2 μg/m 3 and sampling is performedmore » using the 37mm (total dust) sampling method. Since DOE is considering adopting the newer 2009 TLV guidelines, the goal of this study was to determine if the current method of sampling using the 37mm (total dust) sampler would produce results that are comparable to what would be measured using the IOM (inhalable) sampler specific to the application of high energy explosive work at LLNL's remote experimental test facility at Site 300. Side-by-side personal sampling using the two samplers was performed over an approximately two-week period during chamber re-entry and cleanup procedures following detonation of an explosive assembly containing Beryllium (Be). The average ratio of personal sampling results for the IOM (inhalable) vs. 37-mm (total dust) sampler was 1.1:1 with a P-value of 0.62, indicating that there was no statistically significant difference in the performance of the two samplers. Therefore, for the type of activity monitored during this study, the 37-mm sampling cassette would be considered a suitable alternative to the IOM sampler for collecting inhalable particulate matter, which is important given the many practical and economic advantages that it presents. However, similar comparison studies would be necessary for this conclusion to be applied to other types of activities, where earlier studies have shown that the IOM sampler tends to collect higher concentrations of Be compared to the 37-mm cassette, which could complicate compliance with what is already an extremely low exposure limit.« less

A study of airborne chrysotile concentrations associated with handling, unpacking, and repacking boxes of automobile clutch discs.

PubMed

Jiang, George C T; Madl, Amy K; Ingmundson, Kelsey J; Murbach, Dana M; Fehling, Kurt A; Paustenbach, Dennis J; Finley, Brent L

2008-06-01

Although automotive friction products (brakes and manual clutches) historically contained chrysotile asbestos, industrial hygiene surveys and epidemiologic studies of auto mechanics have consistently shown that these workers are not at an increased risk of developing asbestos-related diseases. Airborne asbestos levels during brake repair and brake parts handling have been well-characterized, but the potential exposure to airborne asbestos fibers during the handling of clutch parts has not been examined. In this study, breathing zone samples on the lapel of a volunteer worker (n=100) and area samples at bystander (n=50), remote area (n=25), and ambient (n=9) locations collected during the stacking, unpacking, and repacking of boxes of asbestos-containing clutches, and the subsequent cleanup and clothes handling, were analyzed by phase contrast microscopy (PCM) and transmission electron microscopy (TEM). In addition, fiber morphology and size distribution was evaluated using X-ray diffraction, polarized light microscopy, and ISO analytical methods. It was observed that the (1) airborne asbestos concentrations increased with the number of boxes unpacked and repacked, (2) repetitive stacking of unopened boxes of clutches resulted in higher asbestos concentrations than unpacking and repacking the boxes of clutches, (3) cleanup and clothes handling tasks yielded very low asbestos concentrations. Fiber size and morphology analyses showed that amphibole fibers were not detected in the clutches and that the vast majority (>95%) of the airborne chrysotile fibers were less than 20 microm in length. Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results, it was found that 30-min average airborne chrysotile concentrations (PCM adjusted) were 0.026+/-0.004 f/cc or 0.100+/-0.017 f/cc for a worker unpacking and repacking 1 or 2 boxes of clutches, respectively. The 30-min PCM adjusted average airborne asbestos concentrations at bystander locations ranged from 0.002+/-0.001 f/cc and 0.004+/-0.002 f/cc when 1 or 2 boxes of clutches were handled, respectively. Estimated 8-h TWA asbestos exposures for a worker handling 1 or 2 boxes of clutches over a workday ranged from 0.002 to 0.006 f/cc. The 30-min PCM adjusted average airborne asbestos concentration for a worker continuously stacking unopened boxes of clutches was 0.212+/-0.014 f/cc; the 8-h TWA was 0.013 f/cc. Additionally, 30-min PCM adjusted average airborne asbestos concentrations following cleanup and clothing handling were 0.002+/-0.001 f/cc and 0.002+/-0.002 f/cc, respectively, both resulting in estimated 8-h TWA asbestos exposures of 0.0001 f/cc. The results of this study indicate that the handling, unpacking, and repacking of clutches, and the subsequent cleanup and clothes handling by a worker within a short-term period or over the entire workday, result in exposures below the historical and current short-term and 8-h occupational exposure limits for asbestos.

Assessing occupational mercury exposures and behaviours of artisanal and small-scale gold miners in Burkina Faso using passive mercury vapour badges.

PubMed

Black, Paleah; Richard, Myrianne; Rossin, Ricardo; Telmer, Kevin

2017-01-01

Artisanal and small-scale gold mining (ASGM) is a crucial economic activity in Burkina Faso, however it is associated with significant mercury exposure and health concerns. The aim of the present study was to assess the level of mercury (Hg) vapour exposures and occupational behaviours at a representative site using Hg vapour monitor badges and questionnaires. To our knowledge this is the first time that personal exposure to Hg vapour during ASGM activities has been reported. The study population were ASGM workers who completed a questionnaire (n=100) or participated with an occupational exposure assessment using commercially available passive Hg vapour samplers (n=44). Occupational exposure to Hg was high during open-air burn events with a time weighted average (TWA) exposure of 7026±6857µg/m 3 for burners, and 1412±2870µg/m 3 for bystanders. Most (82%) of the people present at the burn exceeded the Permissible Exposure Limit (PEL) of 100µg/m 3 , and 11% exceeded the level considered to be Immediately Dangerous to Life and Health (IDLH) of 10,000µg/m 3 . Even control workers who were not present at the burn exceeded the PEL (24%), likely due to legacy Hg contamination producing latent Hg releases to the atmosphere. Similarly, 86% of the miners at the burn and 59% of control workers had an 8-h TWA that exceeded the Recommended Exposures Limit (REL). Several occupational behaviours that may contribute to Hg exposures were documented. This study corroborates previous studies suggesting that Hg exposure during amalgam burning is very high, and demonstrates the plausibility of using passive vapour monitoring badges rather than costly and logistically difficult biomonitoring methods. Mercury reduction and elimination interventions are strongly needed to reduce Hg exposure in ASGM communities, particularly as countries come into compliance with the Minamata Convention. Copyright © 2016 Elsevier Inc. All rights reserved.

Personal exposure measurements of school-children to fine particulate matter (PM2.5) in winter of 2013, Shanghai, China.

PubMed

Zhang, Lijun; Guo, Changyi; Jia, Xiaodong; Xu, Huihui; Pan, Meizhu; Xu, Dong; Shen, Xianbiao; Zhang, Jianghua; Tan, Jianguo; Qian, Hailei; Dong, Chunyang; Shi, Yewen; Zhou, Xiaodan; Wu, Chen

2018-01-01

The aim of this study was to perform an exposure assessment of PM2.5 (particulate matter less than 2.5μm in aerodynamic diameter) among children and to explore the potential sources of exposure from both indoor and outdoor environments. In terms of real-time exposure measurements of PM2.5, we collected data from 57 children aged 8-12 years (9.64 ± 0.93 years) in two schools in Shanghai, China. Simultaneously, questionnaire surveys and time-activity diaries were used to estimate the environment at home and daily time-activity patterns in order to estimate the exposure dose of PM2.5 in these children. Principle component regression analysis was used to explore the influence of potential sources of PM2.5 exposure. All the median personal exposure and microenvironment PM2.5 concentrations greatly exceeded the daily 24-h PM2.5 Ambient Air Quality Standards of China, the USA, and the World Health Organization (WHO). The median Etotal (the sum of the PM2.5 exposure levels in different microenvironment and fractional time) of all students was 3014.13 (μg.h)/m3. The concentration of time-weighted average (TWA) exposure of all students was 137.01 μg/m3. The median TWA exposure level during the on-campus period (135.81 μg/m3) was significantly higher than the off-campus period (115.50 μg/m3, P = 0.013 < 0.05). Besides ambient air pollution and meteorological conditions, storey height of the classroom and mode of transportation to school were significantly correlated with children's daily PM2.5 exposure. Children in the two selected schools were exposed to high concentrations of PM2.5 in winter of 2013 in Shanghai. Their personal PM2.5 exposure was mainly associated with ambient air conditions, storey height of the classroom, and children's transportation mode to school.

Characterization of Electrocardiogram Changes Throughout a Marathon

PubMed Central

Callaway, Clifton; Salcido, David; McEntire, Serina; Roth, Ronald; Hostler, David

2014-01-01

Purpose There are few data examining cardiovascular physiology throughout a marathon. This study was devised to characterize electrocardiographic activity continuously throughout a marathon. Methods Cardiac activity was recorded from 19 subjects wearing a Holter monitor during a marathon. The 19 subjects (14 men and 5 women) were aged 39 ± 16 years (mean ± SD) and completed a marathon in 4:32:16 ± 1:23:35. Heart rate (HR), heart rate variability (HRV), T-wave amplitude, T-wave amplitude variability, and T-wave alternans (TWA) were evaluated continuously throughout the marathon. Results Averaged across all subjects, HRV, T-wave amplitude variability, and TWA increased throughout the marathon. Increased variability in T-wave amplitude occurred in 86% of subjects, characterized by complex oscillatory patterns and TWA. Three minutes after the marathon, HR was elevated and HRV was suppressed relative to the pre-marathon state. Conclusion HRV and T-wave amplitude variability, especially in the form of TWA, increase throughout a marathon. Increasing TWA as a marathon progresses likely represents a physiologic process as no arrhythmias or cardiac events were observed. PMID:24832192

Aerosol Emission Monitoring and Assessment of Potential Exposure to Multi-walled Carbon Nanotubes in the Manufacture of Polymer Nanocomposites

PubMed Central

Thompson, Drew; Chen, Sheng-Chieh; Wang, Jing; Pui, David Y.H.

2015-01-01

Recent animal studies have shown that carbon nanotubes (CNTs) may pose a significant health risk to those exposed in the workplace. To further understand this potential risk, effort must be taken to measure the occupational exposure to CNTs. Results from an assessment of potential exposure to multi-walled carbon nanotubes (MWCNTs) conducted at an industrial facility where polymer nanocomposites were manufactured by an extrusion process are presented. Exposure to MWCNTs was quantified by the thermal-optical analysis for elemental carbon (EC) of respirable dust collected by personal sampling. All personal respirable samples collected (n = 8) had estimated 8-h time weighted average (TWA) EC concentrations below the limit of detection for the analysis which was about one-half of the recommended exposure limit for CNTs, 1 µg EC/m3 as an 8-h TWA respirable mass concentration. Potential exposure sources were identified and characterized by direct-reading instruments and area sampling. Area samples analyzed for EC yielded quantifiable mass concentrations inside an enclosure where unbound MWCNTs were handled and near a pelletizer where nanocomposite was cut, while those analyzed by electron microscopy detected the presence of MWCNTs at six locations throughout the facility. Through size selective area sampling it was identified that the airborne MWCNTs present in the workplace were in the form of large agglomerates. This was confirmed by electron microscopy where most of the MWCNT structures observed were in the form of micrometer-sized ropey agglomerates. However, a small fraction of single, free MWCNTs was also observed. It was found that the high number concentrations of nanoparticles, ~200000 particles/cm3, present in the manufacturing facility were likely attributable to polymer fumes produced in the extrusion process. PMID:26209597

Prognostic residual mean flow in an ocean general circulation model and its relation to prognostic Eulerian mean flow

DOE PAGES

Saenz, Juan A.; Chen, Qingshan; Ringler, Todd

2015-05-19

Recent work has shown that taking the thickness-weighted average (TWA) of the Boussinesq equations in buoyancy coordinates results in exact equations governing the prognostic residual mean flow where eddy–mean flow interactions appear in the horizontal momentum equations as the divergence of the Eliassen–Palm flux tensor (EPFT). It has been proposed that, given the mathematical tractability of the TWA equations, the physical interpretation of the EPFT, and its relation to potential vorticity fluxes, the TWA is an appropriate framework for modeling ocean circulation with parameterized eddies. The authors test the feasibility of this proposition and investigate the connections between the TWAmore » framework and the conventional framework used in models, where Eulerian mean flow prognostic variables are solved for. Using the TWA framework as a starting point, this study explores the well-known connections between vertical transfer of horizontal momentum by eddy form drag and eddy overturning by the bolus velocity, used by Greatbatch and Lamb and Gent and McWilliams to parameterize eddies. After implementing the TWA framework in an ocean general circulation model, we verify our analysis by comparing the flows in an idealized Southern Ocean configuration simulated using the TWA and conventional frameworks with the same mesoscale eddy parameterization.« less

Cross-sectional analysis of the possible relationship between lead exposure in the storage-battery industry and changes in biochemical markers of renal, hematopoietic, and hepatic functioning and the reporting of recent abdominal pain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zelenak, J.P.

There is extensive literature documenting the physical effects, such as renal impairment and disruption of hematopoiesis, of lead exposure in occupational cohorts. In addition, a small number of case studies have suggested that lead exposure might result in hepatocellular effects. This study was undertaken to determine if these effects still existed for a population of lead storage battery workers exposed to occupational lead exposures which were lower than those experienced by most lead workers prior to 1978. The relationship between the lead exposure indices,zinc protoporphyrin (ZPP) and a time weighted average blood lead measure (TWA), with twelve biochemical parameters indicativemore » of renal, hematopoietic and hepatic functioning and the reporting of recent abdominal pain was investigated. In addition, the possible modifying effects of alcohol consumption and duration of exposure on the relationship between lead exposure and the biochemical parameters were examined. The subjects for this analysis consisted of 288 lead workers form three lead storage battery plants and a group of 181 workers employed in an industry which did not involve lead exposure. The study was conducted from 1982-83. Comparisons of the lead exposure indices with the dependent variables were made through univariate correlational and hierarchical regression analyses. The lead exposure index, ZPP, was significantly associated wit BUN levels, though less than three percent of the lead and control workers had BUN levels above the normal range, In addition, NPP, was negatively associated with hemoglobin levels at probability levels between 0.052 and 0.055. Furthermore, there were no hemoglobin levels outside of the normal range for any of the sites studied. The other lead exposure index, TWA, was significantly associated with alkaline phosphatase and triglycerides. However, these analyses were not age-adjusted.« less

Electrophysiological studies of shoemakers exposed to sub-TLV levels of n-hexane.

PubMed

Neghab, Masoud; Soleimani, Esmaeel; Khamoushian, Kambiz

2012-01-01

Exposure to n-hexane, a neurotoxic solvent, has been associated with sensorimotor polyneuropathy, both in occupationally exposed workers and in glue-sniffing addicts. The present study was carried out to ascertain whether exposure to sub-TLV levels of n-hexane was associated with electrophysiological abnormalities and to determine if these possible abnormalities have any correlations with parameters such as the biological exposure index (BEI) of this neurotoxic chemical, workers' TWA exposure to n-hexane and/or duration of employment. Twenty-seven asymptomatic male workers from 6 shoemaking workshops were studied and compared with a group of 20 age- and sex-matched normal controls with no history of exposure to any neurotoxic agent. They underwent physical examinations as well as conventional needle electromyographic examinations and sensory and motor nerve conduction studies of upper and lower extremities. The TWA exposure to n-hexane and urinary concentration of free 2,5-hexanedione were also determined. Data were analyzed using version 16.0 of the SPSS/PC statistical package. The TWA exposure to n-hexane was estimated to be 83.2 mg/m(3). Electrophysiological studies showed that the amplitudes of sensory nerve action potential (SAP) for median and sural nerves were significantly lower in exposed subjects than in unexposed normal controls. Additionally, a significant correlation was found between these decreases and the urinary concentration of free 2,5-hexanedione. The significant decrements in SAP amplitudes for the median and sural nerves may be considered as appropriate indicators for early detection of n-hexane-induced peripheral neuropathy in asymptomatic workers with current exposure to sub-TLV levels of n-hexane.

Noise exposure levels for musicians during rehearsal and performance times.

PubMed

McIlvaine, Devon; Stewart, Michael; Anderson, Robert

2012-03-01

The purpose of this study was to determine daily noise doses and 8-hour time weighted averages for rock band musicians, crew members, and spectators during a typical rehearsal and performance using both Occupational Safety and Health Administration (OSHA) and National Institute of Occupational Safety and Health (NIOSH) measurement criteria. Personal noise dosimetry was completed on five members of a rock band during one 2-hr rehearsal and one 4-hr performance. Time-weighted averages (TWA) and daily dose values were calculated using both OSHA and NIOSH criteria and compared to industry guidelines for enrollment in hearing conservation programs and the use of hearing protection devices. TWA values ranged from 84.3 to 90.4 dBA (OSHA) and from 90.0 to 96.4 dBA (NIOSH) during the rehearsal. The same values ranged from 91.0 to 99.7 dBA (OSHA) and 94.0 to 102.8 dBA (NIOSH) for the performance. During the rehearsal, daily noise doses ranged from 45.54% to 106.7% (OSHA) and from 317.74% to 1396.07% (NIOSH). During the performance, doses ranged from 114.66% to 382.49% (OSHA) and from 793.31% to 5970.15% (NIOSH). The musicians in this study were exposed to dangerously high levels of noise and should be enrolled in a hearing conservation programs. Hearing protection devices should be worn, especially during performances. The OSHA measurement criteria yielded values significantly more conservative than those produced by NIOSH criteria. Audiologists should counsel musician-patients about the hazards of excessive noise (music) exposure and how to protect their hearing.

Respirable concrete dust--silicosis hazard in the construction industry.

PubMed

Linch, Kenneth D

2002-03-01

Concrete is an extremely important part of the infrastructure of modern life and must be replaced as it ages. Many of the methods of removing, repairing, or altering existing concrete structures have the potential for producing vast quantities of respirable dust. Since crystalline silica in the form of quartz is a major component of concrete, airborne respirable quartz dust may be produced during construction work involving the disturbance of concrete, thereby producing a silicosis hazard for exposed workers. Silicosis is a debilitating and sometimes fatal lung disease resulting from breathing microscopic particles of crystalline silica. Between 1992 and 1998, the National Institute for Occupational Safety and Health (NIOSH) made visits to construction projects where concrete was being mechanically disturbed in order to obtain data concerning respirable crystalline silica dust exposures. The construction activities studied included: abrasive blasting, concrete pavement sawing and drilling, and asphalt/concrete milling. Air samples of respirable dust were obtained using 10-mm nylon cyclone pre-separators, 37-mm polyvinyl chloride (PVC) filters, and constant-flow pumps calibrated at 1.7 L/min. In addition, high-volume respirable dust samples were obtained on 37-mm PVC filters using 1/2" metal cyclones (Sensidyne model 18) and constant-flow pumps calibrated at 9.0 L/min. Air sample analysis included total weight gain by gravimetric analysis according to NIOSH Analytical Method 600 and respirable crystalline silica (quartz and cristobalite) using x-ray diffraction, as per NIOSH Analytical Method 7500. For abrasive blasting of concrete structures, the respirable crystalline silica (quartz) concentration ranged up to 14.0 mg/m3 for a 96-minute sample resulting in an eight-hour time-weighted average (TWA) of 2.8 mg/m3. For drilling concrete highway pavement the respirable quartz concentrations ranged up to 4.4 mg/m3 for a 358-minute sample, resulting in an eight-hour TWA of 3.3 mg/m3. For concrete wall grinding during new building construction the respirable quartz measurements ranged up to 0.66 mg/m3 for a 191-minute sample, resulting in an eight-hour TWA of 0.26 mg/m3. The air sampling results for concrete sawing ranged up to 14.0 mg/m3 for a 350-minute sample resulting in an eight-hour TWA of 10.0 mg/m3. During the milling of asphalt from concrete highway pavement, the sampling indicated a respirable quartz concentration ranging up to 0.34 mg/m3 for a 504-minute sample, resulting in an eight-hour TWA of 0.36 mg/m3. The results of this work indicate the potential for respirable quartz concentrations involving disturbance of concrete to range up to 280 times the NIOSH Recommended Exposure Limit (REL) of 0.05 mg/m3 assuming exposure for an eight- to ten-hour workday. Considering the aging of the concrete infrastructure in the United States, these results pose a challenge to all who have an interest in preventing silica exposures and the associated disease silicosis.

Lithium in Drinking Water and Incidence of Suicide: A Nationwide Individual-Level Cohort Study with 22 Years of Follow-Up

PubMed Central

Knudsen, Nikoline N.; Schullehner, Jörg; Hansen, Birgitte; Jørgensen, Lisbeth F.; Kristiansen, Søren M.; Voutchkova, Denitza D.; Gerds, Thomas A.; Andersen, Per K.; Bihrmann, Kristine; Grønbæk, Morten; Kessing, Lars V.; Ersbøll, Annette K.

2017-01-01

Suicide is a major public health concern. High-dose lithium is used to stabilize mood and prevent suicide in patients with affective disorders. Lithium occurs naturally in drinking water worldwide in much lower doses, but with large geographical variation. Several studies conducted at an aggregate level have suggested an association between lithium in drinking water and a reduced risk of suicide; however, a causal relation is uncertain. Individual-level register-based data on the entire Danish adult population (3.7 million individuals) from 1991 to 2012 were linked with a moving five-year time-weighted average (TWA) lithium exposure level from drinking water hypothesizing an inverse relationship. The mean lithium level was 11.6 μg/L ranging from 0.6 to 30.7 μg/L. The suicide rate decreased from 29.7 per 100,000 person-years at risk in 1991 to 18.4 per 100,000 person-years in 2012. We found no significant indication of an association between increasing five-year TWA lithium exposure level and decreasing suicide rate. The comprehensiveness of using individual-level data and spatial analyses with 22 years of follow-up makes a pronounced contribution to previous findings. Our findings demonstrate that there does not seem to be a protective effect of exposure to lithium on the incidence of suicide with levels below 31 μg/L in drinking water. PMID:28604590

Lithium in Drinking Water and Incidence of Suicide: A Nationwide Individual-Level Cohort Study with 22 Years of Follow-Up.

PubMed

Knudsen, Nikoline N; Schullehner, Jörg; Hansen, Birgitte; Jørgensen, Lisbeth F; Kristiansen, Søren M; Voutchkova, Denitza D; Gerds, Thomas A; Andersen, Per K; Bihrmann, Kristine; Grønbæk, Morten; Kessing, Lars V; Ersbøll, Annette K

2017-06-10

Suicide is a major public health concern. High-dose lithium is used to stabilize mood and prevent suicide in patients with affective disorders. Lithium occurs naturally in drinking water worldwide in much lower doses, but with large geographical variation. Several studies conducted at an aggregate level have suggested an association between lithium in drinking water and a reduced risk of suicide; however, a causal relation is uncertain. Individual-level register-based data on the entire Danish adult population (3.7 million individuals) from 1991 to 2012 were linked with a moving five-year time-weighted average (TWA) lithium exposure level from drinking water hypothesizing an inverse relationship. The mean lithium level was 11.6 μg/L ranging from 0.6 to 30.7 μg/L. The suicide rate decreased from 29.7 per 100,000 person-years at risk in 1991 to 18.4 per 100,000 person-years in 2012. We found no significant indication of an association between increasing five-year TWA lithium exposure level and decreasing suicide rate. The comprehensiveness of using individual-level data and spatial analyses with 22 years of follow-up makes a pronounced contribution to previous findings. Our findings demonstrate that there does not seem to be a protective effect of exposure to lithium on the incidence of suicide with levels below 31 μg/L in drinking water.

Determination method for nitromethane in workplace air.

PubMed

Takeuchi, Akito; Nishimura, Yasuki; Kaifuku, Yuichiro; Imanaka, Tsutoshi; Natsumeda, Shuichiro; Ota, Hirokazu; Yamada, Shu; Kurotani, Ichiro; Sumino, Kimiaki; Kanno, Seiichiro

2010-01-01

The purpose of this research was to develop a determination method for nitromethane (NM) in workplace air for risk assessment. A suitable sampler and appropriate desorption condition were selected by a recovery test in which a spiked sampler was used. The characteristics of the proposed method, such as recovery, detection limit, and reproducibility, and the storage stability of the sample were examined. A sampling tube containing bead-shaped activated carbon was chosen as the sampler. NM in the sampler was desorbed with acetone and analyzed by a gas chromatograph equipped with a flame ionization detector. The recoveries of NM from the spiked sampler were 81-97% and 80-98% for personal exposure monitoring and working environment measurement, respectively. On the first day of storage in a refrigerator, the recovery from the spiked samplers exceeded 90%; however, it decreased dramatically with increasing storage time. In particular, the decrease was more remarkable for the smaller spiked amounts. The overall LOQ was 2 microg/sample. The relative standard deviation, which represents the overall reproducibility, was 1.1-4.0%. The proposed method enables 4-hour personal exposure monitoring of NM at concentrations equaling 0.001-2 times the threshold limit value-time-weighted average (TLV-TWA: 20 ppm) proposed by the American Conference of Governmental Industrial Hygienists, as well as 10-minute working environment measurement at concentrations equaling 0.02-2 times TLV-TWA. Thus, the proposed method will be useful for estimating worker exposure to NM.

[Analysis on occupational exposure levels and control effectiveness of dust in cement production line of new dry method].

PubMed

Wang, De-jun; Sui, Shao-feng; Kong, Fan-ling; Huang, Dong-hai

2012-11-01

To investigate the occupational exposure levels of dust in new suspension preheated dry process (NSP) cement production line and put forward rectification measures for dust-exposed posts, and to provide ideas for the modern cement production enterprises in dust control and occupational health management. Occupational health field investigation combined with field test were used to measure the time-weighted average concentration (C(TWA)) of the dust in the workplace. Rectification measures were taken for the dust-exposed posts with unqualified dust concentration, and the protective effects of dustproof facilities in the rectified workplace were evaluated. The field investigation revealed incompletely closed dustproof facilities, improperly set dust hoods, excess of dust leakage points, and other problems in the dust-exposed posts of an NSP cement production line before rectification, and the dustproof facilities could hardly exert dust removal effect. The field test showed that the vast majority of dust-exposed posts had the dust concentrations exceeding the occupational exposure limits (OELs), with a qualified rate as low as 31.8%. A series of rectification measures were taken for these posts. After the rectification, the dust-exposed posts demonstrated dramatically dropped C(TWA), and the qualified rate of dust concentration in the dust-exposed posts rose to 90.9%. The dust hazards in NSP cement production line cannot be ignored. Taking appropriate protective measures are critical for curbing dust hazards in modern cement production.

Microvolt T-Wave Alternans

PubMed Central

Verrier, Richard L.; Klingenheben, Thomas; Malik, Marek; El-Sherif, Nabil; Exner, Derek V.; Hohnloser, Stefan H.; Ikeda, Takanori; Martínez, Juan Pablo; Narayan, Sanjiv M.; Nieminen, Tuomo; Rosenbaum, David S.

2014-01-01

This consensus guideline was prepared on behalf of the International Society for Holter and Noninvasive Electrocardiology and is cosponsored by the Japanese Circulation Society, the Computers in Cardiology Working Group on e-Cardiology of the European Society of Cardiology, and the European Cardiac Arrhythmia Society. It discusses the electrocardiographic phenomenon of T-wave alternans (TWA) (i.e., a beat-to-beat alternation in the morphology and amplitude of the ST- segment or T-wave). This statement focuses on its physiological basis and measurement technologies and its clinical utility in stratifying risk for life-threatening ventricular arrhythmias. Signal processing techniques including the frequency-domain Spectral Method and the time-domain Modified Moving Average method have demonstrated the utility of TWA in arrhythmia risk stratification in prospective studies in >12,000 patients. The majority of exercise-based studies using both methods have reported high relative risks for cardiovascular mortality and for sudden cardiac death in patients with preserved as well as depressed left ventricular ejection fraction. Studies with ambulatory electrocardiogram-based TWA analysis with Modified Moving Average method have yielded significant predictive capacity. However, negative studies with the Spectral Method have also appeared, including 2 interventional studies in patients with implantable defibrillators. Meta-analyses have been performed to gain insights into this issue. Frontiers of TWA research include use in arrhythmia risk stratification of individuals with preserved ejection fraction, improvements in predictivity with quantitative analysis, and utility in guiding medical as well as device-based therapy. Overall, although TWA appears to be a useful marker of risk for arrhythmic and cardiovascular death, there is as yet no definitive evidence that it can guide therapy. PMID:21920259

Patrol Officer Daily Noise Exposure.

PubMed

Gilbertson, Lynn R; Vosburgh, Donna J H

2015-01-01

Previous research shows that police officers are at a higher risk for noise induced hearing loss (NIHL). Little data exists on the occupational tasks, outside of the firing range, that might lead to the increased risk of NIHL. The current study collected noise dosimetry from patrol officers in a smaller department and a larger department in southern Wisconsin, United States. The noise dosimeters simultaneously measured noise in three virtual dosimeters that had different thresholds, criterion levels, and exchange rates. The virtual dosimeters were set to: the Occupational Safety and Health Administration (OSHA) hearing conservation criteria (OSHA-HC), the OSHA permissible exposure level criteria (OSHA-PEL), and the American Conference of Governmental Industrial Hygienists (ACGIH). In addition to wearing a noise dosimeter during their respective work days, officers completed a log form documenting the type of task performed, the duration of that task, if the task involved the use of a siren, and officer characteristics that may have influenced their noise exposure, such as the type of dispatch radio unit worn. Analysis revealed that the normalized 8-hour time weighted averages (TWA) for all officers fell below the recommended OSHA and ACGIH exposure limits. The tasks involving the use of the siren had significantly higher levels than the tasks without (p = 0.005). The highest noise exposure levels were encountered when patrol officers were assisting other public safety agencies such as a fire department or emergency medical services (79 dBA). Canine officers had higher normalized 8-hr TWA noise exposure than regular patrol officers (p = 0.002). Officers with an evening work schedule had significantly higher noise exposure than the officers with a day or night work schedule (p = 0.023). There were no significant differences in exposure levels between the two departments (p = 0.22). Results suggest that this study population is unlikely to experience NIHL as established by the OSHA or ACGIH occupational exposure levels from the daily occupational tasks that were monitored.

Worker exposure to volatile organic compounds in the vehicle repair industry.

PubMed

Wilson, Michael P; Hammond, S Katharine; Nicas, Mark; Hubbard, Alan E

2007-05-01

This study evaluated exposures among vehicle repair technicians to hexane, acetone, toluene, and total volatile organic compounds (VOCs). On randomly selected workdays, we observed a characteristic pattern of solvent use among 36 technicians employed in 10 repair shops, each of which used an aerosol solvent product. We obtained quantitative exposure measurements from a subset of nine technicians (employed in three of these shops) who used an aerosol product containing hexane (25-35%), acetone (45-55%), and toluene (5-10%). The time-weighted average (TWA) exposure concentration for task-length breathing zone (BZ) samples (n = 23) was 36 mg/m(3) for hexane, 50 mg/m(3) for acetone, and 10 mg/m(3) for toluene. The TWA area concentrations (n = 49) obtained contemporaneously with BZ samples ranged from 25% to 35% of the BZ concentrations. The solvent emission rate (grams emitted/task time) was correlated with the total VOC exposure concentration (R(2) = 0.45). The proportions of VOCs in the BZ samples were highly correlated (r = 0.89 to 0.95) and were similar to those of the bulk product. Continuous exposure measurements for total VOCs (n = 1238) during 26 tasks produced a mean BZ VOC "pulse" of 394 mg/m(3) within 1 min following initiation of solvent spraying. The geometric mean air speed was 5.2 meters/min in the work areas (n = 870) and was associated with 0.8 air changes per minute in the BZ. The findings suggest that vehicle repair technicians who use aerosol solvent products experience episodic, inhalation exposures to the VOCs contained in these products, and the proportions of VOCs in the breathing zone are similar to those of the bulk product. Because acetone appears to amplify the severity and duration of the neurotoxic effects of n-hexane, products formulated with both hexane and acetone should be avoided. Further evaluation of exposures to VOCs is needed in this industry, along with information on effective alternatives to aerosol solvent products.

A thickness-weighted average perspective of force balance in an idealized circumpolar current

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ringler, Todd Darwin; Saenz, Juan Antonio; Wolfram, Jr., Phillip Justin

The exact, three-dimensional thickness-weighted averaged (TWA) Boussinesq equations are used to diagnose eddy-mean flow interaction in an idealized circumpolar current (ICC). The force exerted by mesoscale eddies on the TWA velocity is expressed as the divergence of the Eliassen-Palm flux tensor. Consistent with previous findings, the analysis indicates that the dynamically relevant definition of the ocean surface layer is comprised of the set of buoyancy coordinates that ever reside at the ocean surface at a given horizontal position. The surface layer is found to be a physically distinct object with a diabatic- and force-balance that is largely isolated from themore » underlying adiabatic region in the interior. Within the ICC surface layer, the TWA meridional velocity is southward/northward in the top/bottom half, and has a value near zero at the bottom. In the top half of the surface layer, the zonal forces due to wind stress and meridional advection of potential vorticity act to accelerate the TWA zonal velocity; equilibrium is obtained by eddies decelerating the zonal flow via a downward flux of eastward momentum that increases with depth. In the bottom half of the surface layer, the accelerating force of the wind stress is balanced by the eddy force and meridional advection of potential vorticity. The bottom of the surface layer coincides with the location where the zonal eddy force, meridional advection of potential vorticity and zonal wind stress force are all zero. The net meridional transport, S f, within the surface layer is a small residual of its southward and northward TWA meridional flows. Furthermore, the mean meridional gradient of surface-layer buoyancy is advected by S f to balance the surface buoyancy fluxs.« less

A thickness-weighted average perspective of force balance in an idealized circumpolar current

DOE PAGES

Ringler, Todd Darwin; Saenz, Juan Antonio; Wolfram, Jr., Phillip Justin; ...

2016-11-22

The exact, three-dimensional thickness-weighted averaged (TWA) Boussinesq equations are used to diagnose eddy-mean flow interaction in an idealized circumpolar current (ICC). The force exerted by mesoscale eddies on the TWA velocity is expressed as the divergence of the Eliassen-Palm flux tensor. Consistent with previous findings, the analysis indicates that the dynamically relevant definition of the ocean surface layer is comprised of the set of buoyancy coordinates that ever reside at the ocean surface at a given horizontal position. The surface layer is found to be a physically distinct object with a diabatic- and force-balance that is largely isolated from themore » underlying adiabatic region in the interior. Within the ICC surface layer, the TWA meridional velocity is southward/northward in the top/bottom half, and has a value near zero at the bottom. In the top half of the surface layer, the zonal forces due to wind stress and meridional advection of potential vorticity act to accelerate the TWA zonal velocity; equilibrium is obtained by eddies decelerating the zonal flow via a downward flux of eastward momentum that increases with depth. In the bottom half of the surface layer, the accelerating force of the wind stress is balanced by the eddy force and meridional advection of potential vorticity. The bottom of the surface layer coincides with the location where the zonal eddy force, meridional advection of potential vorticity and zonal wind stress force are all zero. The net meridional transport, S f, within the surface layer is a small residual of its southward and northward TWA meridional flows. Furthermore, the mean meridional gradient of surface-layer buoyancy is advected by S f to balance the surface buoyancy fluxs.« less

An analysis of collegiate band directors' exposure to sound pressure levels

NASA Astrophysics Data System (ADS)

Roebuck, Nikole Moore

Noise-induced hearing loss (NIHL) is a significant but unfortunate common occupational hazard. The purpose of the current study was to measure the magnitude of sound pressure levels generated within a collegiate band room and determine if those sound pressure levels are of a magnitude that exceeds the policy standards and recommendations of the Occupational Safety and Health Administration (OSHA), and the National Institute of Occupational Safety and Health (NIOSH). In addition, reverberation times were measured and analyzed in order to determine the appropriateness of acoustical conditions for the band rehearsal environment. Sound pressure measurements were taken from the rehearsal of seven collegiate marching bands. Single sample t test were conducted to compare the sound pressure levels of all bands to the noise exposure standards of OSHA and NIOSH. Multiple regression analysis were conducted and analyzed in order to determine the effect of the band room's conditions on the sound pressure levels and reverberation times. Time weighted averages (TWA), noise percentage doses, and peak levels were also collected. The mean Leq for all band directors was 90.5 dBA. The total accumulated noise percentage dose for all band directors was 77.6% of the maximum allowable daily noise dose under the OSHA standard. The total calculated TWA for all band directors was 88.2% of the maximum allowable daily noise dose under the OSHA standard. The total accumulated noise percentage dose for all band directors was 152.1% of the maximum allowable daily noise dose under the NIOSH standards, and the total calculated TWA for all band directors was 93dBA of the maximum allowable daily noise dose under the NIOSH standard. Multiple regression analysis revealed that the room volume, the level of acoustical treatment and the mean room reverberation time predicted 80% of the variance in sound pressure levels in this study.

Evaluation of the toxicity data for peracetic acid in deriving occupational exposure limits: a minireview.

PubMed

Pechacek, Nathan; Osorio, Magdalena; Caudill, Jeff; Peterson, Bridget

2015-02-17

Peracetic acid (PAA) is a peroxide-based chemistry that is highly reactive and can produce strong local effects upon direct contact with the eyes, skin and respiratory tract. Given its increasing prominence in industry, attention has focused on health hazards and associated risks for PAA in the workplace. Occupational exposure limits (OEL) are one means to mitigate risks associated with chemical hazards in the workplace. A mini-review of the toxicity data for PAA was conducted in order to determine if the data were sufficient to derive health-based OELs. The available data for PAA frequently come from unpublished studies that lack sufficient study details, suffer from gaps in available information and often follow unconventional testing methodology. Despite these limitations, animal and human data suggest sensory irritation as the most sensitive endpoint associated with inhalation of PAA. Rodent RD50 data (the concentration estimated to cause a 50% depression in respiratory rate) were selected as the critical studies in deriving OELs. Based on these data, a range of 0.36-0.51mg/m(3) (0.1-0.2ppm) was calculated for a time-weighted average (TWA), and 1.2-1.7mg/m(3) (0.4-0.5ppm) as a range for a short-term exposure limit (STEL). These ranges compare favorably to other published OELs for PAA. Considering the applicable health hazards for this chemistry, a joint TWA/STEL OEL approach for PAA is deemed the most appropriate in assessing workplace exposures to PAA, and the selection of specific values within these proposed ranges represents a risk management decision. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Evaluation of organic-vapor respirator cartridge efficiency for toluene diisocyanate vapor in the presence of methylenechloride or acetone solvent.

PubMed

Dharmarajan, Venkatram; Cummings, Barbara; Lingg, Robert D

2003-08-01

Toluene diisocyanate (TDI) is a widely used raw material in the manufacture of flexible polyurethane foams. Acetone (ACE) and/or methylenechloride (MECL) solvents are the most commonly used solvent-based blowing agents for TDI foams. ACGIH has recommended a TWA exposure limit of 5 ppb for TDI and 500 ppm for ACE. For MECL, OSHA mandates a TWA-exposure limit of 25 ppm. This study evaluated the ability of the organic-vapor respirator cartridges (OVC) to block TDI, as well as the effect of airborne MECL or ACE on the OVCs' efficiency to capture TDI. An aluminum/stainless steel exposure chamber was constructed for simultaneously challenging OVCs in triplicate with a dynamic atmosphere of TDI and ACE or MECL vapor. The challenge atmosphere was generated by combining a TDI-laden nitrogen stream from the headspace of a heated impinger with a humidified stream of the indicated solvent in air. The average challenge concentration for TDI was 275 ppb. The average MECL or ACE concentrations were 547 and 581 ppm, respectively. The challenge atmosphere at room temperature (approximately 24 degrees C) and at 25 or 80 percent relative humidity was drawn through each cartridge at 32 L/min for 40+ hours. During the last 8 hours of the challenge, the atmosphere had only TDI vapor. The pre- and post-cartridge atmospheres were periodically sampled for TDI and solvent. Five tests were conducted--two with MSA and three with North OVCs. Under these extreme test conditions no TDI breakthrough was detected from any OVC. The average-calculated efficiency of the OVCs for TDI was >99.9+ percent. Within the first 6 hours of the challenge the cartridges were saturated with ACE or MECL; nevertheless, continued challenging with TDI and solvents did not cause any TDI breakthrough. The study demonstrates that with an OSHA-compliant respiratory protection program, an OVC can safely be used for 40 hours in most polyurethane foam operations. In typical occupational environments using TDI and solvents, the solvent breakthrough, rather than TDI breakthrough, would be the determining factor for the calculation of respirator cartridge change-out schedules.

Occupational exposure to airborne mercury during gold mining operations near El Callao, Venezuela.

PubMed

Drake, P L; Rojas, M; Reh, C M; Mueller, C A; Jenkins, F M

2001-04-01

The National Institute for Occupational Safety and Health (NIOSH) recently conducted a cross-sectional study during gold mining operations near El Callao, Venezuela. The purpose of the study was to assess mercury exposures and mercury-related microdamage to the kidneys. The study consisted of concurrent occupational hygiene and biological monitoring, and an examination of the processing techniques employed at the different mining facilities. Mercury was used in these facilities to remove gold by forming a mercury-gold amalgam. The gold was purified either by heating the amalgam in the open with a propane torch or by using a small retort. Thirty-eight workers participated in this study. Some participants were employed by a large mining company, while others were considered "informal miners" (self-employed). Mercury exposure was monitored by sampling air from the workers' breathing zones. These full-shift air samples were used to calculate time-weighted average (TWA) mercury exposure concentrations. A questionnaire was administered and a spot urine sample was collected. Each urine sample was analyzed for mercury, creatinine, and N-acetyl-beta-D-glucosaminidase (NAG). The range for the 8-h TWA airborne mercury exposure concentrations was 0.1 to 6,315 micrograms/m3, with a mean of 183 micrograms/m3. Twenty percent of the TWA airborne mercury exposure measurements were above the NIOSH recommended exposure limit (REL) of 50 micrograms/m3, and 26% exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 25 micrograms/m3. The mean urine mercury concentration was 101 micrograms/g creatinine (microgram/g-Cr), and the data ranged from 2.5 to 912 micrograms/g-Cr. Forty-two percent of the study participants had urine mercury concentrations that exceeded the ACGIH biological exposure index (BEI) of 35 micrograms/g-Cr. Urinary NAG excretion is considered a biological marker of preclinical, nonspecific microdamage to the kidney's proximal tubule cells. The mean urine NAG concentration was 3.6 International Units/g-Cr (IU/g-Cr) with a range of 0.5 to 11.5 IU/g-Cr. Three workers had urine NAG levels in excess of the reference values. Correlation analyses found statistically significant correlations between airborne mercury exposure and urine mercury level (P = 0.01), and between urine mercury level and urine NAG excretion (P = 0.01). In addition, the airborne mercury exposure data and urine mercury data were segregated by job tasks. A Wilcoxon rank sum test revealed significant correlations between tasks and mercury exposure (P = 0.03), and between tasks and urine mercury level (P = 0.02). The tasks with the highest mean airborne mercury exposures were "burning the mercury-gold amalgam" and "gold refining/smelting". Recommendations were provided for improving the retort design to better contain mercury, for ventilation in the gold shops, and for medical surveillance and educational programs.

An Open-Source Standard T-Wave Alternans Detector for Benchmarking.

PubMed

Khaustov, A; Nemati, S; Clifford, Gd

2008-09-14

We describe an open source algorithm suite for T-Wave Alternans (TWA) detection and quantification. The software consists of Matlab implementations of the widely used Spectral Method and Modified Moving Average with libraries to read both WFDB and ASCII data under windows and Linux. The software suite can run in both batch mode and with a provided graphical user interface to aid waveform exploration. Our software suite was calibrated using an open source TWA model, described in a partner paper [1] by Clifford and Sameni. For the PhysioNet/CinC Challenge 2008 we obtained a score of 0.881 for the Spectral Method and 0.400 for the MMA method. However, our objective was not to provide the best TWA detector, but rather a basis for detailed discussion of algorithms.

[Risk analysis and assessment of occupational hazard fromindiumand its compounds in manufacture of liquid crystal display panel].

PubMed

Qiu, Haili; Zhou, Wei; Li, Zhimin; Tian, Dongchao; Weng, Shaofan; He, Juntao

2015-08-01

To understand the exposed positions and levels of indium and its compounds in manufacture of liquid crystal displays, and to evaluate the degree of occupational hazard from indium and its compounds. On-site investigation of occupational health, occupational hazard monitoring, and occupational health examination were used to evaluate the degree of occupational hazard from indium and its compounds in three manufacturers of liquid crystal display panel in Shenzhen, Guangdong, China. The time-weighted average (TWA) and short-term exposure limit (STEL) concentrations of indium and its compounds to which sputtering machine operating positions were exposed were less than 0.002~0.004 mg/m³ and 0.006~0.007 mg/m³, respectively, both of which complied with the National Hygienic Standard (PC-TWA = 0.1 mg/m³; PC-STEL = 0.3 mg/m³); the TWA and STEL concentrations of indium and its compounds to which grinding positions were exposed were 0.114~2.98 mg/m³ and 0.31~10.02 mg/m³, respectively, both of which exceeded the National Hygienic Standard with the highest concentration 33-fold higher than the standard. No significant health damages were found in exposed workers according to the results of occupational health examination. The grinding positions are the key to the control of occupational hazard from indium and its compounds in manufacture of liquid crystal display panel. The workers should be equipped with the anti-particulate full-face respirator, which is an effective way to prevent occupational hazard from indium and its compounds.

Application of Polar Organic Chemical Integrative Sampler (POCIS) to monitor emerging contaminants in tropical waters.

PubMed

Bayen, Stéphane; Segovia, Elvagris; Loh, Lay Leng; Burger, David F; Eikaas, Hans S; Kelly, Barry C

2014-06-01

Tools specifically validated for tropical environments are needed to accurately describe the behavior of chemical contaminants in tropical ecosystems. In the present study, sampling rates (Rs) were determined for the commercial pharmaceutical-type Polar Organic Chemical Integrative Sampler (POCIS) with a 45.8cm(2) exposure surface for 35 Pharmaceutically Active Compounds (PhACs) and Endocrine Disrupting Compounds (EDCs), of which eight compounds (albuterol, atorvastatin, diltiazem, dilantin, enalapril, norfluoxetine, risperidone and warfarin) were reported for the first time. These sampling rates were measured in an outdoor laboratory calibration setup to best capture diurnal tropical temperature variations (29±3°C). The effect of stirring and salinity was investigated. For all compounds, the sampling rates were higher under stirred conditions as compared to quiescent conditions. Calibration results in the presence of 30g sodium chloride support that the effects of salinity on POCIS sampling rates are compound-specific. Comparisons between Time-Weight Average (TWA) water concentrations using POCIS and spot sample levels in the field (2 lake and 1 mangrove estuary sites) are presented. Results showed that POCIS TWA concentrations were in agreement with spot sample concentrations for these aquatic systems. Results indicate that POCIS can be used to effectively measure the TWA concentration for a range of PhACs and EDCs in tropical waters. However, based on the results from mass balance and field deployments, POCIS did not appear suitable for compounds with a low mass balance recovery during calibration (e.g. triclosan and linuron in this study). Copyright © 2014 Elsevier B.V. All rights reserved.

Occupational exposure to ethylene oxide--OSHA. Final rule: supplemental statement of reasons.

PubMed

1985-01-02

On June 22, 1984, the Occupational Safety and Health Administration (OSHA) published a final standard for ethylene oxide (EtO) that established a permissible exposure limit of 1 part EtO per million parts of air determined as an 8-hour time--weighted average (TWA) concentration (29 CFR 1910.1047, 49 FR 25734). The standard also includes provisions for methods of exposure control, personal protective equipment, measurement of employee exposure, training, signs, and labels, medical surveillance, regulated areas, emergencies and recordkeeping. The basis for this action was a determination by OSHA, based on human and animal data, that exposure to EtO presents a carcinogenic, mutagenic, genotoxic, reproductive, neurologic, and sensitization hazard to workers. During the rulemaking proceedings that led to the establishment of the 1 ppm TWA, the issue of whether there was a need for a short-term exposure limit (STEL) for workers protection from EtO was raised. OSHA reserved decision on the adoption of a STEL at the conclusion of the rulemaking in order to permit peer review of the available evidence and to review more fully the arguments and pertinent data regarding the STEL issue. Upon receipt of the analyses from most of the peer reviewers, OSHA published a notice to that effect on September 19, 1984 (49 FR 36659) and invited public comment on the pertinent issues addressed in the peer reviews. Based on the entire rulemaking record, including the peer reviews and public comments received since June 22, the Assistant Secretary has determined that adoption of a STEL for EtO is not warranted by the available health evidence, and that a STEL is not reasonably necessary or appropriate for inclusion in the final EtO standard. OSHA has also asked that NIOSH fund certain additional studies related to whether a dose-rate relationship can be established for EtO, and OSHA will review the results of those studies when they become available.

Ototoxic occupational exposures for a stock car racing team: I. Noise surveys.

PubMed

Van Campen, Luann E; Morata, Thais; Kardous, Chucri A; Gwin, Kristin; Wallingford, Kenneth M; Dallaire, Jacques; Alvarez, Frank J

2005-08-01

The National Institute for Occupational Safety and Health (NIOSH) surveyed noise exposure for a professional stock car team at their race shop and during two races at one racetrack. At the team's shop, area sound pressure levels (SPLs) were measured for various work tasks. Equivalent levels (Leqs) ranged from 58 to 104 decibels, A-weighted (dBA). Personal noise dosimetry was conducted for at least one employee for each job description in race car assembly (n = 9). The Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 90 dBA for an 8-hour, 5-dB exchange rate time-weighted average (TWA) was never exceeded, but in two instances values exceeded OSHA's action level of 85 dBA for hearing conservation implementation. The NIOSH recommended exposure limit (REL) of 85 dBA for a 3-dB exchange rate Leq was exceeded for five of the measured jobs. During the races, SPLs averaged above 100 dBA in the pit area where cars undergo adjustments/refueling, both before and during the race. Peak levels reached 140 dB SPL. NIOSH REL was exceeded for every personal noise dosimetry measurement. Recommendations for hearing protection and communication are presented.

Fugitive emissions from nanopowder manufacturing

NASA Astrophysics Data System (ADS)

Trompetter, W. J.; Ancelet, T.; Davy, P. K.; Kennedy, J.

2016-07-01

In response to health and safety questions and concerns regarding particulate matter emissions from equipment used for synthesizing NiFe and TiO2 nanopowders, a study was undertaken to assess their impact on the air quality inside and outside a laboratory where the manufacturing equipment is operated. Elemental concentrations determined by ion beam analysis (IBA) of air particulate matter (PM) samples collected hourly with a StreakerTM sampler were used to identify possible sources and estimate contributions from nanopowder production and other sources. The fugitive nanopowder emissions were the highest at the indoor sampling location when powders were being manufactured. Average fugitive emissions of 210 ng m-3 (1-h average) (maximum 2163 ng m-3 1-h average) represented 2 % (maximum 20 %) of the average PM collected (9359 ng m-3 1-h average). The measured NiFe alloy or TiO2 PM concentrations were much smaller than the 8-h time-weighted average (TWA) workplace exposure standards (WES) for these materials (≥1,000,000 ng m-3). Most PM was found to be from infiltrated outdoor ambient sources. This suggests that nanopowder production in the laboratory is not likely to have adverse health effects on individuals using the equipment, although further improvements can be made to further limit exposure.

29 CFR 1910.1001 - Asbestos.

Code of Federal Regulations, 2013 CFR

2013-07-01

... covered by this standard take place. Certified industrial hygienist (CIH) means one certified in the... TWA employee exposures shall be determined on the basis of one or more samples representing full-shift...-minute short-term employee exposures shall be determined on the basis of one or more samples representing...

T wave alternans as a predictor of recurrent ventricular tachyarrhythmias in ICD recipients: prospective comparison with conventional risk markers

NASA Technical Reports Server (NTRS)

Hohnloser, S. H.; Klingenheben, T.; Li, Y. G.; Zabel, M.; Peetermans, J.; Cohen, R. J.

1998-01-01

INTRODUCTION: The current standard for arrhythmic risk stratification is electrophysiologic (EP) testing, which, due to its invasive nature, is limited to patients already known to be at high risk. A number of noninvasive tests, such as determination of left ventricular ejection fraction (LVEF) or heart rate variability, have been evaluated as additional risk stratifiers. Microvolt T wave alternans (TWA) is a promising new risk marker. Prospective evaluation of noninvasive risk markers in low- or moderate-risk populations requires studies involving very large numbers of patients, and in such studies, documentation of the occurrence of ventricular tachyarrhythmias is difficult. In the present study, we identified a high-risk population, recipients of an implantable cardioverter defibrillator (ICD), and prospectively compared microvolt TWA with invasive EP testing and other risk markers with respect to their ability to predict recurrence of ventricular tachyarrhythmias as documented by ICD electrograms. METHODS AND RESULTS: Ninety-five patients with a history of ventricular tachyarrhythmias undergoing implantation of an ICD underwent EP testing, assessment of TWA, as well as determination of LVEF, baroreflex sensitivity, signal-averaged ECG, analysis of 24-hour Holter monitoring, and QT dispersion from the 12-lead surface ECG. The endpoint of the study was first appropriate ICD therapy for electrogram-documented ventricular fibrillation or tachycardia during follow-up. Kaplan-Meier survival analysis revealed that TWA (P < 0.006) and LVEF (P < 0.04) were the only significant univariate risk stratifiers. EP testing was not statistically significant (P < 0.2). Multivariate Cox regression analysis revealed that TWA was the only statistically significant independent risk factor. CONCLUSIONS: Measurement of microvolt TWA compared favorably with both invasive EP testing and other currently used noninvasive risk assessment methods in predicting recurrence of ventricular tachyarrhythmias in ICD recipients. This study suggests that TWA might also be a powerful tool for risk stratification in low- or moderate-risk patients, and needs to be prospectively evaluated in such populations.

Occupational Noise Exposure of Employees at Locally-Owned Restaurants in a College Town

PubMed Central

Green, Deirdre R.; Anthony, T. Renée

2016-01-01

While many restaurant employees work in loud environments, in both dining and food preparation areas, little is known about worker exposures to noise. The risk of hearing loss to millions of food service workers around the country is unknown. This study evaluated full-shift noise exposure to workers at six locally-owned restaurants to examine risk factors associated with noise exposures during the day shift. Participants included cooks, counter attendants, bartenders, and waiters at full-service restaurants with bar service and at limited-service restaurants that provided counter service only. Assessments were made on weekdays and weekends, both during the summer and the fall (with a local university in session) to examine whether the time of week or year affects noise exposures to this population in a college town. In addition, the relationships between noise exposures and the type of restaurant and job classification were assessed. One-hundred eighty full-shift time-weighted average (TWA) exposures were assessed, using both Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH) criteria. No TWA measurements exceeded the 90 dBA OSHA 8 hr permissible exposure limit, although six projected TWAs exceeded the 85 dBA OSHA hearing conservation action limit. Using NIOSH criteria, TWAs ranged from 69–90 dBA with a mean of 80 dBA (SD = 4 dBA). Nearly 8% (14) of the exposures exceeded the NIOSH 8-hr 85 dBA. Full-shift exposures were larger for all workers in full-service restaurants (p < 0.001) and for cooks (p = 0.003), regardless of restaurant type. The fall semester (p = 0.003) and weekend (p = 0.048) exposures were louder than summer and weekdays. Multiple linear regression analysis suggested that the combination of restaurant type, job classification, and season had a significant effect on restaurant worker noise exposures (p < 0.001) in this college town. While evening/night shift exposures, where noise exposures may be anticipated to be louder, were not assessed, this study identified that restaurant type, job classification, time of week, and season significantly affected the noise exposures for day-shift workers. Intervention studies to prevent noise-induced hearing loss (NIHL) should consider these variables. PMID:25738733

Occupational Noise Exposure of Employees at Locally-Owned Restaurants in a College Town.

PubMed

Green, Deirdre R; Anthony, T Renée

2015-01-01

While many restaurant employees work in loud environments, in both dining and food preparation areas, little is known about worker exposures to noise. The risk of hearing loss to millions of food service workers around the country is unknown. This study evaluated full-shift noise exposure to workers at six locally-owned restaurants to examine risk factors associated with noise exposures during the day shift. Participants included cooks, counter attendants, bartenders, and waiters at full-service restaurants with bar service and at limited-service restaurants that provided counter service only. Assessments were made on weekdays and weekends, both during the summer and the fall (with a local university in session) to examine whether the time of week or year affects noise exposures to this population in a college town. In addition, the relationships between noise exposures and the type of restaurant and job classification were assessed. One-hundred eighty full-shift time-weighted average (TWA) exposures were assessed, using both Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH) criteria. No TWA measurements exceeded the 90 dBA OSHA 8 hr permissible exposure limit, although six projected TWAs exceeded the 85 dBA OSHA hearing conservation action limit. Using NIOSH criteria, TWAs ranged from 69-90 dBA with a mean of 80 dBA (SD = 4 dBA). Nearly 8% (14) of the exposures exceeded the NIOSH 8-hr 85 dBA. Full-shift exposures were larger for all workers in full-service restaurants (p < 0.001) and for cooks (p = 0.003), regardless of restaurant type. The fall semester (p = 0.003) and weekend (p = 0.048) exposures were louder than summer and weekdays. Multiple linear regression analysis suggested that the combination of restaurant type, job classification, and season had a significant effect on restaurant worker noise exposures (p < 0.001) in this college town. While evening/night shift exposures, where noise exposures may be anticipated to be louder, were not assessed, this study identified that restaurant type, job classification, time of week, and season significantly affected the noise exposures for day-shift workers. Intervention studies to prevent noise-induced hearing loss (NIHL) should consider these variables.

Exposure of miners to diesel exhaust particulates in underground nonmetal mines.

PubMed

Cohen, H J; Borak, J; Hall, T; Sirianni, G; Chemerynski, S

2002-01-01

A study was initiated to examine worker exposures in seven underground nonmetal mines and to examine the precision of the National Institute for Occupational Safety and Health (NIOSH) 5040 sampling and analytical method for diesel exhaust that has recently been adopted for compliance monitoring by the Mine Safety and Health Administration (MSHA). Approximately 1000 air samples using cyclones were taken on workers and in areas throughout the mines. Results indicated that worker exposures were consistently above the MSHA final limit of 160 micrograms/m3 (time-weighted average; TWA) for total carbon as determined by the NIOSH 5040 method and greater than the proposed American Conference of Governmental Industrial Hygienists TLV limit of 20 micrograms/m3 (TWA) for elemental carbon. A number of difficulties were documented when sampling for diesel exhaust using organic carbon: high and variable blank values from filters, a high variability (+/- 20%) from duplicate punches from the same sampling filter, a consistent positive interference (+26%) when open-faced monitors were sampled side-by-side with cyclones, poor correlation (r 2 = 0.38) to elemental carbon levels, and an interference from limestone that could not be adequately corrected by acid-washing of filters. The sampling and analytical precision (relative standard deviation) was approximately 11% for elemental carbon, 17% for organic carbon, and 11% for total carbon. An hypothesis is presented and supported with data that gaseous organic carbon constituents of diesel exhaust adsorb onto not only the submicron elemental carbon particles found in diesel exhaust, but also mining ore dusts. Such mining dusts are mostly nonrespirable and should not be considered equivalent to submicron diesel particulates in their potential for adverse pulmonary effects. It is recommended that size-selective sampling be employed, rather than open-faced monitoring, when using the NIOSH 5040 method.

Characterization of naturally occurring airborne diacetyl concentrations associated with the preparation and consumption of unflavored coffee.

PubMed

Pierce, Jennifer S; Abelmann, Anders; Lotter, Jason T; Comerford, Chris; Keeton, Kara; Finley, Brent L

2015-01-01

Diacetyl, a suspected cause of respiratory disorders in some food and flavorings manufacturing workers, is also a natural component of roasted coffee. We characterized diacetyl exposures that would plausibly occur in a small coffee shop during the preparation and consumption of unflavored coffee. Personal (long- and short-term) and area (long-term) samples were collected while a barista ground whole coffee beans, and brewed and poured coffee into cups. Simultaneously, long-term personal samples were collected as two participants, the customers, drank one cup of coffee each per h. Air sampling and analyses were conducted in accordance with OSHA Method 1012. Diacetyl was detected in all long-term samples. The long-term concentrations for the barista and area samples were similar, and ranged from 0.013⿿0.016 ppm; long-term concentrations for the customers were slightly lower and ranged from 0.010⿿0.014 ppm. Short-term concentrations ranged from below the limit of detection (<0.0047 ppm)⿿0.016 ppm. Mean estimated 8 h time-weighted average (8 h TWA) exposures for the barista ranged from 0.007⿿0.013 ppm; these values exceed recommended 8 h TWA occupational exposure limits (OELs) for diacetyl and are comparable to long-term personal measurements collected in various food and beverage production facilities. The concentrations measured based on area sampling were comparable to those measured in the breathing zone of the barista, thus exceedances of the recommended OELs may also occur for coffee shop workers who do not personally prepare coffee (e.g., cashier, sanitation/maintenance). These findings suggest that the practicality and scientific basis of the recommended OELs for diacetyl merit further consideration.

Methods for evaluating temporal trends in noise exposure

PubMed Central

Neitzel, RL; Galusha, D; Dixon-Ernst, C; Rabinowitz, PM

2014-01-01

Objective Hearing conservation programs have been mandatory in many US industries since 1983. Since then, three program elements (audiometric testing, hearing protection, and training) have been the focus of much research. By comparison, little has been done on noise exposure evaluation. Design and study sample Utilizing a large dataset (>10,000 measurements over 20 years) from eight facilities operated by a multinational aluminum manufacturing company, we evaluated several approaches to assessing temporal trends in Time Weighted Average (TWA) exposures and the fraction of measurements exceeding 85 dBA by facility, by exposure group within facility, and by individual worker within facility. Results Overall, exposures declined across locations over the study period. Several facilities demonstrated substantial reductions in exposure, and the results of mean noise levels and exceedance fractions generally showed good agreement. The results of analyses at the individual level diverged with analyses by facility and exposure group within facility, suggesting that individual-level analyses, while challenging, may provide important information not available from coarser levels of analysis. Conclusions Validated metrics are needed to allow for assessment of temporal trends in noise exposure. Such metrics will improve our ability to characterize, in a standardized manner, efforts to reduce noise-induced hearing loss. PMID:24564696

Methods for evaluating temporal trends in noise exposure.

PubMed

Neitzel, R L; Galusha, D; Dixon-Ernst, C; Rabinowitz, P M

2014-03-01

Hearing conservation programs have been mandatory in many US industries since 1983. Since then, three program elements (audiometric testing, hearing protection, and training) have been the focus of much research. By comparison, little has been done on noise exposure evaluation. Temporal trends in time weighted average (TWA) exposures and the fraction of measurements exceeding 85 dBA were evaluated by facility, by exposure group within facility, and by individual worker within facility. A large dataset (> 10 000 measurements over 20 years) from eight facilities operated by a multinational aluminum manufacturing company was studied. Overall, exposures declined across locations over the study period. Several facilities demonstrated substantial reductions in exposure, and the results of mean noise levels and exceedance fractions generally showed good agreement. The results of analyses at the individual level diverged with analyses by facility and exposure group within facility, suggesting that individual-level analyses, while challenging, may provide important information not available from coarser levels of analysis. Validated metrics are needed to allow for assessment of temporal trends in noise exposure. Such metrics will improve our ability to characterize, in a standardized manner, efforts to reduce noise-induced hearing loss.

Airborne asbestos exposures associated with gasket and packing replacement: a simulation study and meta-analysis.

PubMed

Madl, Amy K; Hollins, Dana M; Devlin, Kathryn D; Donovan, Ellen P; Dopart, Pamela J; Scott, Paul K; Perez, Angela L

2014-08-01

Exposures to airborne asbestos during the removal and installation of internal gaskets and packing associated with a valve overhaul were characterized and compared to published data according to different variables (e.g., product, equipment, task, tool, setting, duration). Personal breathing zone and area samples were collected during twelve events simulating gasket and packing replacement, clean-up and clothing handling. These samples were analyzed using PCM and TEM methods and PCM-equivalent (PCME) airborne asbestos concentrations were calculated. A meta-analysis was performed to compare these data with airborne asbestos concentrations measured in other studies involving gaskets and packing. Short-term mechanic and assistant airborne asbestos concentrations during valve work averaged 0.013f/cc and 0.008f/cc (PCME), respectively. Area samples averaged 0.008f/cc, 0.005f/cc, and 0.003f/cc (PCME) for center, bystander, and remote background, respectively. Assuming a tradesman conservatively performs 1-3 gasket and/or packing replacements daily, an average 8-h TWA was estimated to be 0.002-0.010f/cc (PCME). Combining these results in a meta-analysis of the published exposure data showed that the majority of airborne asbestos exposures during work with gaskets and packing fall within a consistent and low range. Significant differences in airborne concentrations were observed between power versus manual tools and removal versus installation tasks. Airborne asbestos concentrations resulting from gasket and packing work during a valve overhaul are consistent with historical exposure data on replacement of asbestos-containing gasket and packing materials involving multiple variables and, in nearly all plausible scenarios, result in average airborne asbestos concentrations below contemporaneous occupational exposure limits for asbestos. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of exposure to ethylene glycol ethers on shipyard painters: II. Male reproduction.

PubMed

Welch, L S; Schrader, S M; Turner, T W; Cullen, M R

1988-01-01

To determine whether 2-ethoxyethanol (2-EE) and 2-methoxyethanol (2-ME) affected the reproductive potential of exposed men, we examined the semen of 73 painters and 40 controls who work in a large shipyard. An industrial hygiene survey was performed to characterize the work environment. The men supplied information on demographic characteristics, medical conditions, personal habits, and reproductive history; underwent a physical examination; and provided a semen sample. Semen samples were analyzed for pH, volume, turbidity, liquidity, viability by stain exclusion and hypo-osmotic stress, sperm density and count per ejaculate, motility using a videotape technique, morphology, and morphometry. Serum was analyzed for testosterone, FSH, and LH. The industrial hygiene survey revealed that the painters were exposed to 2-EE at a time-weighted average (TWA) of 0-80.5 mg/m3 with a mean of 9.9 mg/m3, and to 2-ME at a TWA of 0-17.7 mg/m3 with a mean of 2.6 mg/m3. Painters had an increased prevalence of oligospermia and azoospermia and an increased odds ratio for a lower sperm count per ejaculate, while smoking was controlled. This finding is consistent with prior animal studies and with one human study. Potential biases and confounding of the data are discussed.

Development and evaluation of a semi-empirical two-zone dust exposure model for a dusty construction trade.

PubMed

Jones, Rachael M; Simmons, Catherine; Boelter, Fred

2011-06-01

Drywall finishing is a dusty construction activity. We describe a mathematical model that predicts the time-weighted average concentration of respirable and total dusts in the personal breathing zone of the sander, and in the area surrounding joint compound sanding activities. The model represents spatial variation in dust concentrations using two-zones, and temporal variation using an exponential function. Interzone flux and the relationships between respirable and total dusts are described using empirical factors. For model evaluation, we measured dust concentrations in two field studies, including three workers from a commercial contracting crew, and one unskilled worker. Data from the field studies confirm that the model assumptions and parameterization are reasonable and thus validate the modeling approach. Predicted dust C(twa) were in concordance with measured values for the contracting crew, but under estimated measured values for the unskilled worker. Further characterization of skill-related exposure factors is indicated.

Proposal for single and mixture biological exposure limits for sevoflurane and nitrous oxide at low occupational exposure levels.

PubMed

Accorsi, Antonio; Valenti, Simona; Barbieri, Anna; Raffi, Giovanni Battista; Violante, Francesco Saverio

2003-03-01

Assessment of individual exposures to sevoflurane plus nitrous oxide (N(2)O) by biological monitoring of unmodified analytes in post-shift urine of exposed personnel. Anaesthetics in urine and breathing area were monitored in 124 subjects in 11 operating theatres. Passive samplers were collected after 2.5-7 h of exposure, at the same time as post-shift urinary samples, to evaluate the individual time-weighted average (TWA) exposures to sevoflurane and N(2)O. A static headspace sampler coupled with a gas chromatograph mass spectrometer was used for analytical determinations (sensitivity sufficient to reveal biological/environmental exposures of 0.1 microg/l(urine) and 50 ppb for sevoflurane, and 1 microg/l(urine) and 80 ppb for N(2)O). Median (range) post-shift urinary and environmental values were 1.2 microg/l(urine) (0.1-5.0) and 0.4 ppm (0.05-3.0) for sevoflurane ( n=107) and 10.9 microg/l(urine) (0.5-74.9) and 8.6 ppm (0.2-123.4) for N(2)O ( n=121) (all low-exposure range). At log-log regression, urinary levels closely correlated with environmental data (sevoflurane, r(2)=0.7538; N(2)O, r(2)=0.8749). Biological equivalent limits (BELs) based on National Institute for Occupational Safety and Health (NIOSH) TWA exposure limits, calculated as means of regression slope and y-intercept, were 3.6 microg/l(urine) for sevoflurane (corresponding to 2 ppm) and 22.3 microg/l(urine) for N(2)O (corresponding to 25 ppm). Individual "mixture BELs", which we calculated by applying the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) mix formula to biomarker values and using the obtained NIOSH-based BELs as a reference, closely correlated with mixture TLVs (rho=0.816, Lin's concordance test). CONCLUSIONS. We propose urinary sevoflurane as a new, specific, internal dose biomarker for routine biological monitoring of personal exposures among operating-theatre personnel, and use of reliable "mixture BELs" to provide safer levels of internal exposure for workers exposed to mixtures of sevoflurane and N(2)O, and conceivably also to other mixtures of toxicants with possible additive effects.

Using Smart Devices to Measure Intermittent Noise in the Workplace

PubMed Central

Roberts, Benjamin; Neitzel, Richard Lee

2017-01-01

Purpose: To determine the accuracy of smart devices (iPods) to measure intermittent noise and integrate a noise dose in the workplace. Materials and Methods: In experiment 1, four iPods were each paired with a Larson Davis Spark dosimeter and exposed to randomly fluctuating pink noise in a reverberant sound chamber. Descriptive statistics and the mean difference between the iPod and its paired dosimeter were calculated for the 1-s data logged measurements. The calculated time weighted average (TWA) was also compared between the devices. In experiment 2, 15 maintenance workers and 14 office workers wore an iPod and dosimeter during their work-shift for a maximum of five workdays. A mixed effects linear regression model was used to control for repeated measures and to determine the effect of the device type on the projected 8-h TWA. Results: In experiment 1, a total of 315,306 1-s data logged measurements were made. The interquartile range of the mean difference fell within ±2.0 A-weighted decibels (dBA), which is the standard used by the American National Standards Institute to classify a type 2 sound level meter. The mean difference of the calculated TWA was within ±0.5 dBA except for one outlier. In experiment 2, the results of the mixed effects model found that, on average, iPods measured an 8-h TWA 1.7 dBA higher than their paired dosimeters. Conclusion: This study shows that iPods have the ability to make reasonably accurate noise measurements in the workplace, but they are not as accurate as traditional noise dosimeters. PMID:29192614

Assessment of noise in the airplane cabin environment.

PubMed

Zevitas, Christopher D; Spengler, John D; Jones, Byron; McNeely, Eileen; Coull, Brent; Cao, Xiaodong; Loo, Sin Ming; Hard, Anna-Kate; Allen, Joseph G

2018-03-15

To measure sound levels in the aircraft cabin during different phases of flight. Sound level was measured on 200 flights, representing six aircraft groups using continuous monitors. A linear mixed-effects model with random intercept was used to test for significant differences in mean sound level by aircraft model and across each flight phase as well as by flight phase, airplane type, measurement location and proximity to engine noise. Mean sound levels across all flight phases and aircraft groups ranged from 37.6 to >110 dB(A) with a median of 83.5 dB(A). Significant differences in noise levels were also observed based on proximity to the engines and between aircraft with fuselage- and wing mounted engines. Nine flights (4.5%) exceeded the recommended 8-h TWA exposure limit of 85 dB(A) by the NIOSH and ACGIH approach, three flights (1.5%) exceeded the 8-h TWA action level of 85 dB(A) by the OSHA approach, and none of the flights exceeded the 8-h TWA action level of 90 dB(A) by the OSHA PEL approach. Additional characterization studies, including personal noise dosimetry, are necessary to document accurate occupational exposures in the aircraft cabin environment and identify appropriate response actions. FAA should consider applying the more health-protective NIOSH/ACGIH occupational noise recommendations to the aircraft cabin environment.

The TW Hydrae association: trigonometric parallaxes and kinematic analysis

NASA Astrophysics Data System (ADS)

Ducourant, C.; Teixeira, R.; Galli, P. A. B.; Le Campion, J. F.; Krone-Martins, A.; Zuckerman, B.; Chauvin, G.; Song, I.

2014-03-01

Context. The nearby TW Hydrae association (TWA) is currently a benchmark for the study of the formation and evolution of young low-mass stars, circumstellar disks, and the imaging detection of planetary companions. For these studies, it is crucial to evaluate the distance to group members in order to access their physical properties. Membership of several stars is strongly debated and age estimates vary from one author to another with doubts about coevality. Aims: We revisit the kinematic properties of the TWA in light of new trigonometric parallaxes and proper motions to derive the dynamical age of the association and physical parameters of kinematic members. Methods: Using observations performed with the New Technology Telescope (NTT) from ESO we measured trigonometric parallaxes and proper motions for 13 stars in TWA. Results: With the convergent point method we identify a co-moving group with 31 TWA stars. We deduce kinematic distances for seven members of the moving group that lack trigonometric parallaxes. A traceback strategy is applied to the stellar space motions of a selection of 16 of the co-moving objects with accurate and reliable data yielding a dynamical age for the association of t ≃ 7.5 ± 0.7 Myr. Using our new parallaxes and photometry available in the literature we derive stellar ages and masses from theoretical evolutionary models. Conclusions: With new parallax and proper motion measurements from this work and current astrometric catalogs we provide an improved and accurate database for TWA stars to be used in kinematical analysis. We conclude that the dynamical age obtained via traceback strategy is consistent with previous age estimates for the TWA, and is also compatible with the average ages derived in the present paper from evolutionary models for pre-main-sequence stars. Based on observations performed at the European Southern Observatory, Chile (79.C-0229, 81.C-0143, 82.C-0103, 83.C-0102, 84.C-0014).

Accounting for differing exposure patterns between laboratory tests and the field in the assessment of long-term risks of pesticides to terrestrial vertebrates.

PubMed

Fischer, David L

2005-11-01

Long-term risks of pesticides to birds and mammals are currently assessed by comparing effects thresholds determined in chronic laboratory studies to exposure levels expected to occur in the field. However, there is often a mismatch between exposure patterns tested in the laboratory tests (exposure levels held constant) and those experienced by animals in the field (exposure levels varying over time). Three methods for addressing this problem are presented and discussed. Time-weighted averaging (TWA) converts a variable field exposure regime to a single value that can be compared directly to the laboratory test results. Body-burden modeling (BBM) is applied to both laboratory and field exposure regimes allowing a straightforward comparison of body residue levels expected for each situation. Temporal analysis (TA) uses expert judgment to decide if the length of time exposure exceeds a toxicity threshold is long enough to cause biologically significant effects. To reduce uncertainty in long-term assessments, the conduct of specialized laboratory tests in which test subjects are administered a time-varying exposure that mimics what occurs in the field should be considered. Such tests may also be useful testing the validity of each of these assessment methods.

Health survey of former workers in a Norwegian coke plant: Part. 1. Estimation of historical exposures

PubMed Central

Romundstad, P. R.; Ronneberg, A.; Leira, H. L.; Bye, T.

1998-01-01

OBJECTIVE: To estimate historical exposure levels at a coke plant for all agents considered to be of importance for epidemiological studies of mortality and cancer incidence. METHODS: Time weighted average exposure (8 h TWA) was estimated based on personal measurements for polycyclic aromatic hydrocarbons (PAHs) and carbonaceous particulates. Exposure to quartz was estimated relative to the concentration of carbonaceous particulates. These estimates were adjusted for the use of airstream helmets. Exposure to other agents were estimated qualitatively (asbestos, benzene, and arsenic) or semi-quantitatively (carbon monoxide (CO) and heat) based on measurements and other indicators of exposure. RESULTS: Exposure to PAHs was highest for those who worked at the top of the ovens (300 micrograms/m3) in the period from 1970-6. The estimated PAH exposure was reduced to an average of 65 micrograms/m3 after the introduction of exposure control measures in 1976. The estimates for carbonaceous particulates ranged from 1 to 16 mg/m3, with the highest exposure for workers at the top of the ovens and at the coke screening station. CONCLUSIONS: The exposure of greatest concern in this study is to PAHs, but exposures to carbonaceous particulates and CO may also be of importance. The major limitations of this study are the lack of personal measurements before 1975 and the total lack of measurements for some of the exposed categories of workers. Despite these limitations, we think that this assessment reflects the actual exposures for most of the former employees. The assessment thus provides a reasonable tool for the subsequent epidemiological study and for future epidemiological follow up studies at the coke plant.   PMID:9861184

[Expression of heat shock protein 70 and its mRNA in career exposure to manganese].

PubMed

Chen, Wenwen; Shao, Hua; Chi, Mingfeng; Zhang, Zhihu; Shan, Yongle; Zou, Wei

2015-10-01

To analyze the expression levels of heat shock protein70 (HSPs70) and HSPs70 mRNA in different exposure to manganese, and research the neuroprotective effect on the career exposure to manganese. From 2008 to 2009, with cross-sectional study design, and in a locomotive and rolling stock works, by stratified random sampling method, the exposed sample consisted of 180 welders from different welding shops and 100 unexposed in the last three years, non-welder controls with age-matched workers of similar socioeconomic status from the same industry. The control workers had not been exposed to neurotoxic chemicals. The mRNA expressions of four different metabolic enzyme were detected by SYBR Green I quantitative real-time polymerase chain reaction. The expression levels of the two enzymes mRNA in different exposure to manganese were analyzed. The expressions of HSPs70 were detected by Western blot. The concentration of air manganese was determined by GFAAS. The average concentration of 8 h time (8h-TWA) was used to express the level of individual exposure to manganese, according to the air manganese workplace occupational exposure limit (8h-TWA=0.15 mg/m3), the exposed group is divided into high exposed group (>0.15 mg/m3) and low exposure group (<0.15 mg/m3). The individuals exposed to manganese dose of exposed group ((0.25±0.31) mg/m3) was higher than the control group ((0.06±0.02) mg/m3) (t=6.15, P=0.001); individuals exposed to manganese dose of high exposure group for (0.42±0.34) mg/m3, which was higher than low exposure group (0.09±0.07) mg/m3 (t=9.80, P=0.001). HSPs70 mRNA and protein of exposure group (5.65±0.21, 3.26±0.15) were higher than the reference group (0.41±0.03, 1.32±0.12) (t=18.91, t=8.68, P=0.001). HSP70 mRNA and protein of high exposure group (6.48±0.37, 3.67±0.26) were higher than the low exposure group (5.15±0.23, 3.02±0.19) (t=3.24, t=2.01, P=0.003, P=0.043). The expression of peripheral blood lymphocytes HSPs70 level and HSPs70 mRNA workers exposed to manganese increased and protect nerve cells from related to Mn stimulation induced lipid peroxidation damag.

[Epidemiological study of cytopenia among benzene-exposed workers and its influential factors].

PubMed

Peng, Juan-juan; Liu, Mei-xia; Yang, Feng; Guo, Wei-wei; Zhuang, Ran; Jia, Xian-dong

2013-03-01

To evaluate the benzene exposure level and cytopenia among the benzene exposed workers in Shanghai, China and to analyze the influential factors for the health of benzene-exposed workers. A total of 3314 benzene-exposed workers, who were from 85 benzene-related enterprises selected by stratified random sampling based on enterprise sizes and industries, were included in the study. The time-weighted average (TWA) concentration of benzene in each workshop was measured by individual sampling and fixed point sampling, and the benzene exposure level in workshop was evaluated accordingly. The occupational health examination results and health status of benzene-exposed workers were collected. The median of TW A concentrations of benzene was 0.3 mg/m3. The TWA concentrations measured at 7 ( 1.4%) of the 504 sampling points were above the safety limit. Of the 7 points, 3 were from large enterprises, 2 from medium enterprises, and 2 from small enterprises; 3 were from shipbuilding industry, 1 from chemical industry, and 3 from light industry. Of the 3314 benzene-exposed workers, 451 ( 13.6%) had cytopenia, including 339 males ( 339/2548, 13.3%) and 112 females ( 112/766, 14.6% ). There were significant differences in the incidence rates of leukopenia and neutropenia among the benzene-exposed workers of different sexes and ages (P<0.05); there were significant differences in the incidence rate of cytopenia among the benzene-exposed workers of different ages and working years ( P<0.05 ); there were significant differences in the incidence of neutropenia among the benzene exposed workers of different working years ( P<0.05). Monitoring and intervention measures should be enhanced to protect the benzene-exposed workers in the large enterprises in shipbuilding industry and medium and private enterprises in chemical industry from occupational hazards.

Airborne arsenic and urinary excretion of arsenic metabolites during boiler cleaning operations in a Slovak coal-fired power plant.

PubMed Central

Yager, J W; Hicks, J B; Fabianova, E

1997-01-01

Little information is available on the relationship between occupational exposure to inorganic arsenic in coal fly ash and urinary excretion of arsenic metabolites. This study ws undertaken in a coal-fired power plant in Slovakia during a routine maintenance outage. Arsenic was measured in the breathing zone of workers during 5 consecutive workdays, and urine samples were obtained for analysis of arsenic metabolites--inorganic arsenic (Asi), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)--prior to the start of each shift. Results from a small number of cascade impactor air samples indicated that approximately 90% of total particle mass and arsenic was present in particle size fractions >/= 3.5 micron. The 8-hr time-weighted average (TWA) mean arsenic air concentration was 48.3 microg/m3 (range 0.17-375.2) and the mean sum of urinary arsenic (SigmaAs) metabolites was 16.9 microg As/g creatinine (range 2.6-50.8). For an 8-hr TWA of 10 microg/m3 arsenic from coal fly ash, the predicted mean concentration of the SigmaAs urinary metabolites was 13.2 microg As/G creatinine [95% confidence interval (CI), 10.1-16.3). Comparisons with previously published studies of exposure to arsenic trioxide vapors and dusts in copper smelters suggest that bioavailability of arsenic from airborne coal fly ash (as indicated by urinary excretion) is about one-third that seen in smelters and similar settings. Arsenic compound characteristics, matrix composition, and particle size distribution probably play major roles in determining actual uptake of airborne arsenic. Images Figure 1. A Figure 1. B Figure 2. PMID:9347899

[Nanosilver--Occupational exposure limits].

PubMed

Świdwińska-Gajewska, Anna Maria; Czerczak, Sławomir

2015-01-01

Historically, nanosilver has been known as colloidal silver composed of particles with a size below 100 nm. Silver nanoparticles are used in many technologies, creating a wide range of products. Due to antibacterial properties nanosilver is used, among others, in medical devices (wound dressings), textiles (sport clothes, socks), plastics and building materials (paints). Colloidal silver is considered by many as an ideal agent in the fight against pathogenic microorganisms, unlike antibiotics, without side effects. However, in light of toxicological research, nanosilver is not inert to the body. The inhalation of silver nanoparticles have an adverse effect mainly on the liver and lung of rats. The oxidative stress caused by reactive oxygen species is responsible for the toxicity of nanoparticles, contributing to cytotoxic and genotoxic effects. The activity of the readily oxidized nanosilver surface underlies the molecular mechanism of toxicity. This leads to the release of silver ions, a known harmful agent. Occupational exposure to silver nanoparticles may occur in the process of its manufacture, formulation and also usage during spraying, in particular. In Poland, as well as in other countries of the world, there is no separate hygiene standards applicable to nanomaterials. The present study attempts to estimate the value of MAC-TWA (maximum admissible concentration--the time-weighted average) for silver--a nano-objects fraction, which amounted to 0.01 mg/m3. The authors are of the opinion that the current value of the MAC-TWA for silver metallic--inhalable fraction (0.05 mg/m3) does not provide sufficient protection against the harmful effects of silver in the form of nano-objects. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Respiratory Symptoms in Hospital Cleaning Staff Exposed to a Product Containing Hydrogen Peroxide, Peracetic Acid, and Acetic Acid

PubMed Central

Hawley, Brie; Casey, Megan; Virji, Mohammed Abbas; Cummings, Kristin J.; Johnson, Alyson; Cox-Ganser, Jean

2017-01-01

Cleaning and disinfecting products consisting of a mixture of hydrogen peroxide (HP), peracetic acid (PAA), and acetic acid (AA) are widely used as sporicidal agents in health care, childcare, agricultural, food service, and food production industries. HP and PAA are strong oxidants and their mixture is a recognized asthmagen. However, few exposure assessment studies to date have measured HP, PAA, and AA in a health care setting. In 2015, we performed a health and exposure assessment at a hospital where a new sporicidal product, consisting of HP, PAA, and AA was introduced 16 months prior. We collected 49 full-shift time-weighted average (TWA) air samples and analyzed samples for HP, AA, and PAA content. Study participants were observed while they performed cleaning duties, and duration and frequency of cleaning product use was recorded. Acute upper airway, eye, and lower airway symptoms were recorded in a post-shift survey (n = 50). A subset of 35 cleaning staff also completed an extended questionnaire that assessed symptoms reported by workers as regularly occurring or as having occurred in the previous 12 months. Air samples for HP (range: 5.5 to 511.4 ppb) and AA (range: 6.7 to 530.3 ppb) were all below established US occupational exposure limits (OEL). To date, no full-shift TWA OEL for PAA has been established in the United States, however an OEL of 0.2 ppm has been suggested by several research groups. Air samples for PAA ranged from 1.1 to 48.0 ppb and were well below the suggested OEL of 0.2 ppm. Hospital cleaning staff using a sporicidal product containing HP, PAA, and AA reported work-shift eye (44%), upper airway (58%), and lower airway (34%) symptoms. Acute nasal and eye irritation were significantly positively associated with increased exposure to the mixture of the two oxidants: HP and PAA, as well as the total mixture (TM) of HP, PAA, and AA. Shortness of breath when hurrying on level ground or walking up a slight hill was significantly associated with increased exposure to the oxidant mixture (P = 0.017), as well as the TM (P = 0.026). Our results suggest that exposure to a product containing HP, PAA, and AA contributed to eye and respiratory symptoms reported by hospital cleaning staff at low levels of measured exposure. PMID:29077798

Inflammatory markers and exposure to airborne particles among workers in a Swedish pulp and paper mill.

PubMed

Westberg, Håkan; Elihn, Karine; Andersson, Eva; Persson, Bodil; Andersson, Lennart; Bryngelsson, Ing-Liss; Karlsson, Cathe; Sjögren, Bengt

2016-07-01

To study the relationship between exposure to airborne particles in a pulp and paper mill and markers of inflammation and coagulation in blood. Personal sampling of inhalable dust was performed for 72 subjects working in a Swedish pulp and paper mill. Stationary measurements were used to study concentrations of total dust, respirable dust, PM10 and PM2.5, the particle surface area and the particle number concentrations. Markers of inflammation, interleukins (IL-1b, IL-6, IL-8, and IL-10), C-reactive protein (CRP), serum amyloid A (SAA), and fibrinogen and markers of coagulation factor VIII, von Willebrand, plasminogen activator inhibitor, and D-dimer were measured in plasma or serum. Sampling was performed on the last day of the work free period of 5 days, before and after the shift the first day of work and after the shifts the second and third day. In a mixed model analysis, the relationship between particulate exposures and inflammatory markers was determined. Sex, age, smoking, and BMI were included as covariates. The average 8-h time-weighted average (TWA) air concentration levels of inhalable dust were 0.30 mg/m(3), range 0.005-3.3 mg/m(3). The proxies for average 8-h TWAs of respirable dust were 0.045 mg/m(3). Significant and consistent positive relations were found between several exposure metrics (PM 10, total and inhalable dust) and CRP, SAA and fibrinogen taken post-shift, suggesting a dose-effect relationship. This study supports a relationship between occupational particle exposure and established inflammatory markers, which may indicate an increased risk of cardiovascular disease.

29 CFR 1910.1048 - Formaldehyde.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., these tests shall consist of forced vital capacity (FVC), forced expiratory volume in one second (FEV1... of any employee within each exposure group. (ii) The initial monitoring process shall be repeated... areas where the concentration of airborne formaldehyde exceeds either the TWA or the STEL and post all...

29 CFR 1910.1048 - Formaldehyde.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., these tests shall consist of forced vital capacity (FVC), forced expiratory volume in one second (FEV1... of any employee within each exposure group. (ii) The initial monitoring process shall be repeated... areas where the concentration of airborne formaldehyde exceeds either the TWA or the STEL and post all...

29 CFR 1910.1048 - Formaldehyde.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., these tests shall consist of forced vital capacity (FVC), forced expiratory volume in one second (FEV1... of any employee within each exposure group. (ii) The initial monitoring process shall be repeated... areas where the concentration of airborne formaldehyde exceeds either the TWA or the STEL and post all...

Exposure assessment of ETBE in gas station workers and gasoline tanker truck drivers.

PubMed

Eitaki, Yoko; Kawai, Toshio; Omae, Kazuyuki

2011-01-01

In order to measure occupational exposure concentrations of ethyl tertiary-butyl ether (ETBE), we developed a diffusive sampling method for monitoring ETBE and performed an ETBE exposure assessment. The applicability of diffusive samplers was examined by exposing the samplers to ETBE vapor in test chambers. The personal exposure levels of workers and airborne concentrations were measured at 4 gas stations. The ETBE sampling rate for the diffusive samplers (VOC-SD, Sigma-Aldrich Japan) was 25.04 ml/min (25°C). Compared with the active sampling method, the diffusive samplers could be used for short-term measurements and in environments containing a mixture of organic solvents. The geometric mean (GM) of TWA-8h ETBE was 0.08 ppm (0.02-0.28 ppm) in 28 gas station workers and 0.04 ppm (0.01-0.21 ppm) in 2 gasoline tanker truck drivers. With regard to ETBE airborne concentrations, the GM was 4.12 ppm (0.93-8.71 ppm) at the handles of hanging pumps but dropped to less than 0.01 ppm (less than 0.01-0.01 ppm) at the side of a public road. The diffusive sampling method can be used for the measurement of occupational ETBE exposure. The threshold limit of TLV-TWA 5 ppm recommended by the ACGIH was not exceeded in any of the workers in this study.

Associations between Bisphenol A Exposure and Reproductive Hormones among Female Workers

PubMed Central

Miao, Maohua; Yuan, Wei; Yang, Fen; Liang, Hong; Zhou, Zhijun; Li, Runsheng; Gao, Ersheng; Li, De-Kun

2015-01-01

The associations between Bisphenol-A (BPA) exposure and reproductive hormone levels among women are unclear. A cross-sectional study was conducted among female workers from BPA-exposed and unexposed factories in China. Women’s blood samples were collected for assay of follicle-stimulating hormone (FSH), luteinizing hormone (LH), 17β-Estradiol (E2), prolactin (PRL), and progesterone (PROG). Their urine samples were collected for BPA measurement. In the exposed group, time weighted average exposure to BPA for an 8-h shift (TWA8), a measure incorporating historic exposure level, was generated based on personal air sampling. Multiple linear regression analyses were used to examine linear associations between urine BPA concentration and reproductive hormones after controlling for potential confounders. A total of 106 exposed and 250 unexposed female workers were included in this study. A significant positive association between increased urine BPA concentration and higher PRL and PROG levels were observed. Similar associations were observed after the analysis was carried out separately among the exposed and unexposed workers. In addition, a positive association between urine BPA and E2 was observed among exposed workers with borderline significance, while a statistically significant inverse association between urine BPA and FSH was observed among unexposed group. The results suggest that BPA exposure may lead to alterations in female reproductive hormone levels. PMID:26506366

Associations between Bisphenol A Exposure and Reproductive Hormones among Female Workers.

PubMed

Miao, Maohua; Yuan, Wei; Yang, Fen; Liang, Hong; Zhou, Zhijun; Li, Runsheng; Gao, Ersheng; Li, De-Kun

2015-10-22

The associations between Bisphenol-A (BPA) exposure and reproductive hormone levels among women are unclear. A cross-sectional study was conducted among female workers from BPA-exposed and unexposed factories in China. Women's blood samples were collected for assay of follicle-stimulating hormone (FSH), luteinizing hormone (LH), 17β-Estradiol (E2), prolactin (PRL), and progesterone (PROG). Their urine samples were collected for BPA measurement. In the exposed group, time weighted average exposure to BPA for an 8-h shift (TWA8), a measure incorporating historic exposure level, was generated based on personal air sampling. Multiple linear regression analyses were used to examine linear associations between urine BPA concentration and reproductive hormones after controlling for potential confounders. A total of 106 exposed and 250 unexposed female workers were included in this study. A significant positive association between increased urine BPA concentration and higher PRL and PROG levels were observed. Similar associations were observed after the analysis was carried out separately among the exposed and unexposed workers. In addition, a positive association between urine BPA and E2 was observed among exposed workers with borderline significance, while a statistically significant inverse association between urine BPA and FSH was observed among unexposed group. The results suggest that BPA exposure may lead to alterations in female reproductive hormone levels.

A simulation of T-wave alternans vectocardiographic representation performed by changing the ventricular heart cells action potential duration.

PubMed

Janusek, D; Kania, M; Zaczek, R; Zavala-Fernandez, H; Maniewski, R

2014-04-01

The presence of T wave alternans (TWA) in the surface ECG signals has been recognized as a marker of electrical instability, and is hypothesized to be related to patients at increased risk for ventricular arrhythmias. In this paper we present a TWA simulation study. The TWA phenomenon was simulated by changing the duration of the ventricular heart cells action potential. The magnitude was calculated in the surface ECG with the use of the time domain method. The spatially concordant TWA, where during one heart beat all ventricular cells display a short-duration action potential and during the next beat they exhibit a long-duration action potential, as well as the discordant TWA, where at least one region is out of phase, was simulated. The vectocardiographic representation was employed. The obtained results showed a high level of T-loop pattern and location disturbances connected to the discordant TWA simulation in contrast to the concordant one. This result may be explained by the spatial heterogeneity of the ventricular repolarization process, which could be higher for the discordant TWA than for the concordant TWA. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Exposure to airborne asbestos during removal and installation of gaskets and packings: a review of published and unpublished studies.

PubMed

Madl, Amy K; Clark, Katherine; Paustenbach, Dennis J

2007-01-01

In recent years, questions have been raised about the health risks to persons who have been occupationally exposed to asbestos-containing gaskets and packing materials used in pipes, valves, and machinery (pumps, autos, etc.). Up until the late 1970s, these materials were widely used throughout industrial and maritime operations, refineries, chemical plants, naval ships, and energy plants. Seven simulation studies and four work-site industrial hygiene studies of industrial and maritime settings involving the collection of more than 300 air samples were evaluated to determine the likely airborne fiber concentrations to which a worker may have been exposed while working with encapsulated asbestos-containing gaskets and packing materials. Each study was evaluated for the representativeness of work practices, analytical methods, sample size, and potential for asbestos contamination (e.g., insulation on valves or pipes used in the study). Specific activities evaluated included the removal and installation of gaskets and packings, flange cleaning, and gasket formation. In all but one of the studies relating to the replacement of gaskets and packing using hand-held tools, the short-term average exposures were less than the current 30-min OSHA excursion limit of 1 fiber per cubic centimeter (f/cc) and all of the long-term average exposures were less than the current 8-h permissible exposure limit time-weighted average (PEL-TWA) of 0.1 f/cc. The weight of evidence indicates that the use of hand tools and hand-operated power tools to remove or install gaskets or packing as performed by pipefitters or other tradesmen in nearly all plausible situations would not have produced airborne concentrations in excess of contemporaneous regulatory levels.

Statistical modelling of formaldehyde occupational exposure levels in French industries, 1986-2003.

PubMed

Lavoué, Jérôme; Vincent, Raymond; Gérin, Michel

2006-04-01

Occupational exposure databanks (OEDBs) have been cited as sources of exposure data for exposure surveillance and exposure assessment in epidemiology. In 2003, an extract was made from COLCHIC, the French national OEDB, of all concentrations of formaldehyde. The data were analysed with extended linear mixed-effects models in order to identify influent variables and elaborate a multi-sector picture of formaldehyde exposures. Respectively, 1401 and 1448 personal and area concentrations were available for the analysis. The fixed effects of the personal and area models explained, respectively, 57 and 53% of the total variance. Personal concentrations were related to the sampling duration (short-term higher than TWA levels), decreased with the year of sampling (-9% per year) and were higher when local exhaust ventilation was present. Personal levels taken during planned visits and for occupational illness notification purpose were consistently lower than those taken during ventilation modification programmes or because the hygienist suspected the presence of significant risk or exposure. Area concentrations were related to the sampling duration (short-term higher than TWA levels), and decreased with the year of sampling (-7% per year) and when the measurement sampling flow increased. Significant within-facility (correlation coefficient 0.4-0.5) and within-sampling campaign correlation (correlation coefficient 0.8) was found for both area and personal data. The industry/task classification appeared to have the greatest influence on exposure variability while the sample duration and the sampling flow were significant in some cases. Estimates made from the models for year 2002 showed elevated formaldehyde exposure in the fields of anatomopathological and biological analyses, operation of gluing machinery in the wood industry, operation and monitoring of mixers in the pharmaceutical industry, and garages and warehouses in urban transit authorities.

Airborne asbestos take-home exposures during handling of chrysotile-contaminated clothing following simulated full shift workplace exposures.

PubMed

Sahmel, Jennifer; Barlow, Christy A; Gaffney, Shannon; Avens, Heather J; Madl, Amy K; Henshaw, John; Unice, Ken; Galbraith, David; DeRose, Gretchen; Lee, Richard J; Van Orden, Drew; Sanchez, Matthew; Zock, Matthew; Paustenbach, Dennis J

2016-01-01

The potential for para-occupational, domestic, or take-home exposures from asbestos-contaminated work clothing has been acknowledged for decades, but historically has not been quantitatively well characterized. A simulation study was performed to measure airborne chrysotile concentrations associated with laundering of contaminated clothing worn during a full shift work day. Work clothing fitted onto mannequins was exposed for 6.5 h to an airborne concentration of 11.4 f/cc (PCME) of chrysotile asbestos, and was subsequently handled and shaken. Mean 5-min and 15-min concentrations during active clothes handling and shake-out were 3.2 f/cc and 2.9 f/cc, respectively (PCME). Mean airborne PCME concentrations decreased by 55% 15 min after clothes handling ceased, and by 85% after 30 min. PCM concentrations during clothes handling were 11-47% greater than PCME concentrations. Consistent with previously published data, daily mean 8-h TWA airborne concentrations for clothes-handling activity were approximately 1.0% of workplace concentrations. Similarly, weekly 40-h TWAs for clothes handling were approximately 0.20% of workplace concentrations. Estimated take-home cumulative exposure estimates for weekly clothes handling over 25-year working durations were below 1 f/cc-year for handling work clothes contaminated in an occupational environment with full shift airborne chrysotile concentrations of up to 9 f/cc (8-h TWA).

Coast Guard exposure to gasoline, MTBE, and benzene vapors during inspection of tank barges.

PubMed

Davenport, A C; Glynn, T J; Rhambarose, H

2000-01-01

A field study was conducted June through August 1996 in an attempt to quantify short-term exposure levels to Coast Guard personnel performing routine inspection activities aboard commercial tank barges carrying gasoline. Transfer and fleeting operations were monitored in the ports of Pittsburgh, Pa., Huntington, W.Va., Baton Rouge, La., and Galveston, Tex. A total of 43 personal and 68 area samples were analyzed for benzene and total hydrocarbons as gasoline ("gasoline"). Results can be summarized as follows: Personal exposure to benzene gave 15-min time-weighted-average (TWA) results ranging from <0.10 to 0.50 ppm. Area benzene levels ranged from <0.04 to 170 ppm. Personal monitoring for gasoline revealed a range of <2.0 to 590 mg/m3 with a GM of 23 mg/m3. Area sample results for gasoline ranged from 1.7 to 90,000 mg/m3. Twelve personal samples were collected for methyl-tert butyl ether (MTBE). Only two of these were above the limit of detection and had 15-min time-weighted averages of 22 ppm and 1.3 ppm. Eighteen MTBE area samples ranged in value from <3.0 to 38 ppm. Although none of the personal samples met or exceeded proposed or established short-term exposure standards, many of the area sampling results indicated that a significant risk of acute exposure exists in the vicinity of valves, pressure lines, and connections. This includes anticipated sources such as pressure vent valves as well as unexpected sources resulting from structural deficiencies onboard the vessels. These results further emphasize the value of safe work practices and proper vessel maintenance in controlling exposure to harmful chemicals.

Respiratory Symptoms in Hospital Cleaning Staff Exposed to a Product Containing Hydrogen Peroxide, Peracetic Acid, and Acetic Acid.

PubMed

Hawley, Brie; Casey, Megan; Virji, Mohammed Abbas; Cummings, Kristin J; Johnson, Alyson; Cox-Ganser, Jean

2017-12-15

Cleaning and disinfecting products consisting of a mixture of hydrogen peroxide (HP), peracetic acid (PAA), and acetic acid (AA) are widely used as sporicidal agents in health care, childcare, agricultural, food service, and food production industries. HP and PAA are strong oxidants and their mixture is a recognized asthmagen. However, few exposure assessment studies to date have measured HP, PAA, and AA in a health care setting. In 2015, we performed a health and exposure assessment at a hospital where a new sporicidal product, consisting of HP, PAA, and AA was introduced 16 months prior. We collected 49 full-shift time-weighted average (TWA) air samples and analyzed samples for HP, AA, and PAA content. Study participants were observed while they performed cleaning duties, and duration and frequency of cleaning product use was recorded. Acute upper airway, eye, and lower airway symptoms were recorded in a post-shift survey (n = 50). A subset of 35 cleaning staff also completed an extended questionnaire that assessed symptoms reported by workers as regularly occurring or as having occurred in the previous 12 months. Air samples for HP (range: 5.5 to 511.4 ppb) and AA (range: 6.7 to 530.3 ppb) were all below established US occupational exposure limits (OEL). To date, no full-shift TWA OEL for PAA has been established in the United States, however an OEL of 0.2 ppm has been suggested by several research groups. Air samples for PAA ranged from 1.1 to 48.0 ppb and were well below the suggested OEL of 0.2 ppm. Hospital cleaning staff using a sporicidal product containing HP, PAA, and AA reported work-shift eye (44%), upper airway (58%), and lower airway (34%) symptoms. Acute nasal and eye irritation were significantly positively associated with increased exposure to the mixture of the two oxidants: HP and PAA, as well as the total mixture (TM)of HP, PAA, and AA. Shortness of breath when hurrying on level ground or walking up a slight hill was significantly associated with increased exposure to the oxidant mixture (P = 0.017), as well as the TM (P = 0.026). Our results suggest that exposure to a product containing HP, PAA, and AA contributed to eye and respiratory symptoms reported by hospital cleaning staff at low levels of measured exposure. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2017.

Modeled occupational exposures to gas-phase medical laser-generated air contaminants.

PubMed

Lippert, Julia F; Lacey, Steven E; Jones, Rachael M

2014-01-01

Exposure monitoring data indicate the potential for substantive exposure to laser-generated air contaminants (LGAC); however the diversity of medical lasers and their applications limit generalization from direct workplace monitoring. Emission rates of seven previously reported gas-phase constituents of medical laser-generated air contaminants (LGAC) were determined experimentally and used in a semi-empirical two-zone model to estimate a range of plausible occupational exposures to health care staff. Single-source emission rates were generated in an emission chamber as a one-compartment mass balance model at steady-state. Clinical facility parameters such as room size and ventilation rate were based on standard ventilation and environmental conditions required for a laser surgical facility in compliance with regulatory agencies. All input variables in the model including point source emission rates were varied over an appropriate distribution in a Monte Carlo simulation to generate a range of time-weighted average (TWA) concentrations in the near and far field zones of the room in a conservative approach inclusive of all contributing factors to inform future predictive models. The concentrations were assessed for risk and the highest values were shown to be at least three orders of magnitude lower than the relevant occupational exposure limits (OELs). Estimated values do not appear to present a significant exposure hazard within the conditions of our emission rate estimates.

Differential diagnosis of cardiovascular diseases and T-wave alternans

NASA Astrophysics Data System (ADS)

Ramasamy, Mouli; Varadan, Vijay K.

2016-04-01

T wave alternans (TWA) is the variation of the T-wave in electrocardiogram that is observed between periodic beats. TWA is one of the important precursors used to diagnose sudden cardiac death (SCD). Several clinical studies have tried to determine the significance of using TWA analysis to detect abnormalities that may lead to Ventricular Arrhythmias, as well as establish metrics to perform risk stratification for cardiovascular patients with prior cardiac episodes. The statistical significance of TWA in predicting ventricular arrhythmias has been established in patients across several diagnoses. Studies have also shown the significance of the predictive value of TWA analysis in post myocardial infarction patients, risk of SCD, congestive heart failure, ischemic cardiomyopathy, and Chagas disease.

Comparison of task-based exposure metrics for an epidemiologic study of isocyanate inhalation exposures among autobody shop workers.

PubMed

Woskie, Susan R; Bello, Dhimiter; Gore, Rebecca J; Stowe, Meredith H; Eisen, Ellen A; Liu, Youcheng; Sparer, Judy A; Redlich, Carrie A; Cullen, Mark R

2008-09-01

Because many occupational epidemiologic studies use exposure surrogates rather than quantitative exposure metrics, the UMass Lowell and Yale study of autobody shop workers provided an opportunity to evaluate the relative utility of surrogates and quantitative exposure metrics in an exposure response analysis of cross-week change in respiratory function. A task-based exposure assessment was used to develop several metrics of inhalation exposure to isocyanates. The metrics included the surrogates, job title, counts of spray painting events during the day, counts of spray and bystander exposure events, and a quantitative exposure metric that incorporated exposure determinant models based on task sampling and a personal workplace protection factor for respirator use, combined with a daily task checklist. The result of the quantitative exposure algorithm was an estimate of the daily time-weighted average respirator-corrected total NCO exposure (microg/m(3)). In general, these four metrics were found to be variable in agreement using measures such as weighted kappa and Spearman correlation. A logistic model for 10% drop in FEV(1) from Monday morning to Thursday morning was used to evaluate the utility of each exposure metric. The quantitative exposure metric was the most favorable, producing the best model fit, as well as the greatest strength and magnitude of association. This finding supports the reports of others that reducing exposure misclassification can improve risk estimates that otherwise would be biased toward the null. Although detailed and quantitative exposure assessment can be more time consuming and costly, it can improve exposure-disease evaluations and is more useful for risk assessment purposes. The task-based exposure modeling method successfully produced estimates of daily time-weighted average exposures in the complex and changing autobody shop work environment. The ambient TWA exposures of all of the office workers and technicians and 57% of the painters were found to be below the current U.K. Health and Safety Executive occupational exposure limit (OEL) for total NCO of 20 microg/m(3). When respirator use was incorporated, all personal daily exposures were below the U.K. OEL.

49 CFR 227.5 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... second or less. Decibel (dB) means a unit of measurement of sound pressure levels. dB(A) means the sound... operate similar equipment under similar conditions. Sound level or Sound pressure level means ten times... an eight-hour time-weighted-average sound level (TWA) of 85 dB(A), or, equivalently, a dose of 50...

Research project shows importance of pre-employment hearing testing.

PubMed

Karlovich, R S

1992-02-01

Forty employees received pure-tone baseline hearing tests at the time they began employment as LSM operators for the U.S. Postal Services; the workplace eight-hour average sound level (TWA) was 85 dBA. Nineteen operators from the original group had their hearing retested three years later. None of the retested subjects showed large or systematic changes in hearing sensitivity over the three-year period. For the audiometric frequencies most susceptible to noise exposure (3000, 4000, 6000 Hz), only 5 percent of the operators showed a bilateral change in threshold greater than 5 dB at any frequency, and none of them showed more than a 10 dB threshold change in both ears. None of the operators displayed a Standard Threshold Shift as described by OSHA. The data further suggested that many workers began their LSM work assignment with a pre-existing hearing loss and, based upon audiometric and history information, the impairment probably resulted from prior occupational and/or nonoccupational noise exposure. The importance of hearing-conservation programs for employees is emphasized.

Styrene vapor control systems in FRP yacht plants.

PubMed

Todd, W F

1985-01-01

The production of large (greater than 25-ft) fiber-reinforced plastic (FRP) yachts has presented problems of styrene exposure in excess of the Occupational Safety and Health Administration permissible exposure level (OSHA PEL) of 100 ppm. Also, the National Institute for Occupational Safety and Health (NIOSH) is currently recommending a 10-hour workshift, 40-hour workweek time weighted average (TWA) of 50 ppm for styrene. Meeting this challenge will require a system of engineering, work practice, personal protective equipment, and monitoring control measures. NIOSH has performed a study of the engineering controls in three FRP yacht plants. Work practices and the use of personal protective equipment (PPE) were also considered in the evaluation. The three systems evaluated included a dilution system, a local ventilation system, and a push-pull ventilation system. The cost of constructing and operating these systems was not evaluated in this study. Study results indicated that each type of ventilation system can meet the present PEL of 100 ppm styrene; however, it is not certain that these systems can meet a lower PEL of 50 ppm styrene.

Study on OELs for enzyme-containing detergent in China.

PubMed

Zhang, X D; Liang, Y X; Lee, C S; Jin, T Y

2004-01-01

This study is aimed at setting occupational exposure levels for total detergent dust and enzymes in detergent industries. The study population consisted of 795 workers from four enzyme-containing detergent manufacturing plants (A1, A2, B1 and B2), and 156 control workers from an electronic assembly factory. Work environment monitoring was conducted using high volume of air sampler fro measuring the concentration of total dust (mg/m3), and analyzing the level of enzyme (ng/m3) by ELISA method. A standard questionnaires, pulmonary function test, and skin prick test are used to assess health effects. The levels of detergent total dust varied from 0.2 mg/m3 to 12.54 mg/m3. For enzyme levels, in A1, B1 and B2, the concentration ranged from non-detectable to 9.92 ng/m3 and in A2, the concentration was analyzed by enzyme activity methods and was expressed as Gu/m3 (1 Gu/m3 = 16 ng/m3). The concentration is between 0.16-31.36 ng/m3. Non-specific irritation rates in exposed workers were significantly higher than that in controls. Based on the data collected from A1, B1 and control plants, 95% benchmark dose lower bound were calculated as 1.17 mg/m3. The difference of pulmonary function between exposed workers and controls is not significant. The results of SPT showed that neither Savinase- nor Alcalase-induced sensitization was found in controls. The prevalence rates of sensitization for Savinase and Alcalase were ranged between 3.2% and 31% in all enzyme-containing detergent manufacturers investigated. No case of occupational asthma was observed. For total dust, 1 mg/m3 is suggested as permissible concentration-time weighted average (PC-TWA), and 2 mg/m3 as permissible concentration-short term exposure limit (PC-STEL). For the enzyme Subtilisins, 15 ng/m3 is suggested as PC-TWA, and 30 ng/m3 as PC-STEL.

Comparative Risks of Cancer from Drywall Finishing Based on Stochastic Modeling of Cumulative Exposures to Respirable Dusts and Chrysotile Asbestos Fibers.

PubMed

Boelter, Fred W; Xia, Yulin; Dell, Linda

2015-05-01

Sanding joint compounds is a dusty activity and exposures are not well characterized. Until the mid 1970s, asbestos-containing joint compounds were used by some people such that sanding could emit dust and asbestos fibers. We estimated the distribution of 8-h TWA concentrations and cumulative exposures to respirable dusts and chrysotile asbestos fibers for four worker groups: (1) drywall specialists, (2) generalists, (3) tradespersons who are bystanders to drywall finishing, and (4) do-it-yourselfers (DIYers). Data collected through a survey of experienced contractors, direct field observations, and literature were used to develop prototypical exposure scenarios for each worker group. To these exposure scenarios, we applied a previously developed semi-empirical mathematical model that predicts area as well as personal breathing zone respirable dust concentrations. An empirical factor was used to estimate chrysotile fiber concentrations from respirable dust concentrations. On a task basis, we found mean 8-h TWA concentrations of respirable dust and chrysotile fibers are numerically highest for specialists, followed by generalists, DIYers, and bystander tradespersons; these concentrations are estimated to be in excess of the respective current but not historical Threshold Limit Values. Due to differences in frequency of activities, annual cumulative exposures are highest for specialists, followed by generalists, bystander tradespersons, and DIYers. Cumulative exposure estimates for chrysotile fibers from drywall finishing are expected to result in few, if any, mesothelioma or excess lung cancer deaths according to recently published risk assessments. Given the dustiness of drywall finishing, we recommend diligence in the use of readily available source controls. © 2014 Society for Risk Analysis.

Evaluation of exposures to fluorocarbon 113 in a horizontal and a vertical laminar airflow clean room.

PubMed

Bloom, T F; Egeland, G M

1999-01-01

Exposures to 1,1,2-trichloro-1,2,2-trifluoroethane or fluorocarbon (FC) 113 were evaluated in a horizontal laminar airflow (HLAF) clean room and a vertical laminar airflow (VLAF) clean room. A full period consecutive samples measurement strategy was employed. Data were used to calculate 8-hour time-weighted averages (8-TWA) for major work groups and to characterize exposures associated with specific cleaning tasks. The MIRAN 1B infrared analyzer was used to estimate peak concentrations. In the HLAF clean room, 8-TWAs ranged from 193 to 439 ppm; in the VLAF clean room, 8-TWAs ranged from 110 to 935 ppm. These levels were below the current Occupational Safety and Health Administration permissible exposure limit and the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit for FC 113 of 1000 ppm. Short-term sample concentrations ranged from 104 ppm (inspection) to 1080 ppm (assembly) in the HLAF clean room and 51 ppm (packaging)-3380 ppm (flushing) in the VLAF clean room. In the VLAF clean room, several short-term concentrations measured during the flushing task--1421 ppm and 2522 ppm--were above the NIOSH short-term exposure limit (STEL) of 1250 ppm. These data suggest the possibility that the STEL may be exceeded for tasks involving direct work with liquid FC 113. Peak exposure levels may be reduced by modification of worker position in the HLAF clean room and by use of open wire tables in the VLAF clean room.

Interpretation and classification of microvolt T wave alternans tests

NASA Technical Reports Server (NTRS)

Bloomfield, Daniel M.; Hohnloser, Stefan H.; Cohen, Richard J.

2002-01-01

Measurement of microvolt-level T wave alternans (TWA) during routine exercise stress testing now is possible as a result of sophisticated noise reduction techniques and analytic methods that have become commercially available. Even though this technology is new, the available data suggest that microvolt TWA is a potent predictor of arrhythmia risk in diverse disease states. As this technology becomes more widely available, physicians will be called upon to interpret microvolt TWA tracings. This review seeks to establish uniform standards for the clinical interpretation of microvolt TWA tracings.

Adaptive match filter based method for time vs. amplitude characterization of microvolt ECG T-wave alternans.

PubMed

Burattini, Laura; Zareba, Wojciech; Burattini, Roberto

2008-09-01

To develop a new method for non-invasive identification of patients prone to ventricular tachyarrhythmia and sudden cardiac death, an adaptive match-filter (AMF) was applied to detect and characterize T-wave alternans (TWA) in 200 coronary artery diseased (CAD) patients compared with 176 healthy (H) subjects. TWA was characterized in terms of duration (TWAD), amplitude (TWAA), and magnitude (TWAM, defined as the product of TWAD times TWAA). A criterion derived from these parameters, estimated over the H-population, allowed discrimination between a risk (TWA+) and a normality (NO TWA) zone in the TWAD-TWAA plane. To gain further ability to discriminate among different risk levels, the TWA+ zone was divided into four sub-zones respectively characterized by low duration and low amplitude (LDLA), low duration and high amplitude (LDHA), high duration and low amplitude (HDLA), and high duration and high amplitude (HDHA). With our methodology, 21 CAD-patients (10.5%) were identified as TWA+, 9 falling in the LDLA zone, 4 in the HDLA, 7 in the LDHA, and 1 in the HDHA. These results are in agreement with clinical expectations and pave the way to further clinical follow-up studies finalized to analyze pathophysiological implications and risk factors associated to each TWA+ zone.

Research on the traditional Chinese medicine treating gastrointestinal motility in diabetic rats by improving biomechanical remodeling and neuroendocrine regulation

PubMed Central

Tian, Jiaxing; Li, Min; Zhao, Jingbo; Li, Junling; Liu, Guifang; Zhen, Zhong; Cao, Yang; Gregersen, Hans; Tong, Xiaolin

2017-01-01

Previous studies have demonstrated that TWA, a Chinese herbal medicine, could significantly improve the symptoms of patients with diabetic gastrointestinal dysfunction. However, the specific mechanism of regulating intestinal peristalsis has not been found. This study aimed to discover TWA’s therapeutic mechanism for regulating intestinal motility. The intestinal propulsion rate of diabetic rats was significantly increased after treatment with TWA for 8 weeks. Aiming at the mechanical structure, biomechanical testing indicated that TWA can significantly decrease the no-load intestinal wall thickness, cross-sectional area, and angular spread in a zero-stress state. Notably, intestinal stress-strain curve shifted to the right, which indicated TWA can inhibit intestinal hyperplasia and hardening and improve biomechanical remodeling. Further study of the mechanism revealed that TWA significantly inhibited the expression of AGE in the villi, crypt, and muscle and RAGE in crypt and upregulated the expression of nerve regulator (PSD95, C-kit and SCF). Radioimmunoassay showed TWA treatment decreased levels of serum somatostatin and vasoactive intestinal peptide. Moreover, associations were found between the intestinal propulsion rate with the morphologic and biomechanical remodeling parameters, changes of nerve factors, and endocrine hormones. Morphologic and biomechanical remodeling of the intestinal wall are the pathologic basis of gastrointestinal dysfunction. TWA can benefit intestinal motility by improving biomechanical and morphologic remodeling and by regulating expression of neuroendocrine factors. The results showed that the effect of TWA was dose-dependent, the higher the dose, the greater is the improvement. Thus, traditional Chinese medicine might be a valuable tool for treating diabetic gastrointestinal dysfunction. PMID:28559973

TW HYA ASSOCIATION MEMBERSHIP AND NEW WISE-DETECTED CIRCUMSTELLAR DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneider, Adam; Song, Inseok; Melis, Carl, E-mail: aschneid@physast.uga.edu, E-mail: song@physast.uga.edu, E-mail: cmelis@ucsd.edu

2012-07-20

We assess the current membership of the nearby, young TW Hydrae association and examine newly proposed members with the Wide-field Infrared Survey Explorer (WISE) to search for infrared excess indicative of circumstellar disks. Newly proposed members TWA 30A, TWA 30B, TWA 31, and TWA 32 all show excess emission at 12 and 22 {mu}m providing clear evidence for substantial dusty circumstellar disks around these low-mass, {approx}8 Myr old stars that were previously shown to likely be accreting circumstellar material. TWA 30B shows large amounts of self-extinction, likely due to an edge-on disk geometry. We also confirm previously reported circumstellar disksmore » with WISE and determine a 22 {mu}m excess fraction of 42{sup +10}{sub -{sub 9}}% based on our results.« less

The utility of T-wave alternans during the morning in the summer for the risk stratification of patients with Brugada syndrome.

PubMed

Sakamoto, Shogo; Takagi, Masahiko; Kakihara, Jun; Hayashi, Yusuke; Doi, Atsushi; Sugioka, Kenichi; Yoshiyama, Minoru

2017-03-01

The prognostic value of the seasonal variations of T-wave alternans (TWA) and heart rate variability (HRV), and the seasonal distribution of ventricular fibrillation (VF) in Brugada syndrome (Br-S) is unknown. We assessed the utility of seasonal variations in TWA and HRV for risk stratification in Br-S using a 24-h multichannel Holter electrocardiogram (24-M-ECG). We enrolled 81 patients with Br-S (grouped according to their history of VF, n = 12; syncope, n = 8; no symptoms, n = 61) who underwent 24-M-ECG in all four seasons. Precordial electrodes were attached to the third (3L-V2) and fourth (4L-V2, 4L-V5) intercostal spaces. We determined the maximum TWA (max-TWA) values and calculated HRV during night and morning time periods for all seasons. During a follow-up period of 5.8 ± 2.8 years, 11 patients experienced new VF episodes and there was a peak in new VF episodes in the summer. The VF group had the greatest 3L-V2 max-TWA value during morning time in the summer among the three groups and showed higher 3L-V2 max-TWA value than in the other seasons. The cutoff value for the 3L-V2 max-TWA during morning time in the summer was determined to be 42 µV using ROC analysis (82 % sensitivity, 74 % specificity; p = 0.0006). Multivariate analysis revealed that a 3L-V2 max-TWA value ≥42 µV during morning time in the summer and previous VF episodes were predictors of future VF episodes. The 3L-V2 max-TWA value during morning time in the summer may be a useful predictor of future VF episodes in Br-S.

T wave alternans threshold late after repair of tetralogy of Fallot

NASA Technical Reports Server (NTRS)

Cheung, Michael M H.; Weintraub, Robert G.; Cohen, Richard J.; Karl, Tom R.; Wilkinson, James L.; Davis, Andrew M.

2002-01-01

INTRODUCTION: Sustained microvolt-level T wave alternans (TWA) is a marker of increased risk for malignant ventricular arrhythmia. There is a significant risk of arrhythmia and sudden death after repair of congenital heart disease. The aim of this study was to determine the prevalence and characteristics of TWA after repair of tetralogy of Fallot (TOF). METHODS AND RESULTS: TWA was evaluated during bicycle exercise in 49 subjects who had consecutively undergone transatrial-transpulmonary repair. Median values for age, age at repair, and follow-up duration were 14.9 years (11.5-20.8), 1.6 years (0.2-4.9), and 11.6 years (9.4-17.2), respectively. All patients were in New York Heart Association functional class I and were asymptomatic. Median QRS duration was 120 msec (80-150). Sustained TWA was detected in 7 (23%) of 31 subjects with adequate tests. In these 7 subjects, median onset heart rate (HR) was 120 (98-155). Median HR threshold as a percentage of predicted maximum HR (220 - age) was 58% (48-77). Sustained TWA prevalence was not significantly different compared with normal subjects (7/31 vs 9/83; P = 0.1). Onset HR in the TOF group was significantly lower [mean (SD) of 122 (20) vs 139 (12), P < 0.05]. In the TOF group with sustained TWA, the TWA occurred in 4 of 7 at <60% predicted maximum HR versus 1 of 9 normal subjects (P < 0.05); 3 of 7 had onset HR <120 versus 0 of 9 normal subjects (P < 0.03). There was no significant difference in age, gender, transannular patch use, restrictive right ventricular physiology, QRS duration, QTc, QT/QRS dispersion, or nonsustained ventricular tachycardia in subjects with or those without sustained TWA. CONCLUSION: The onset HR for sustained TWA is significantly lower after repair of TOF. Further study is required to determine whether this represents an increased risk for arrhythmia in this patient group.

The TWA 3 Young Triple System: Orbits, Disks, Evolution

NASA Astrophysics Data System (ADS)

Kellogg, Kendra; Prato, L.; Torres, Guillermo; Schaefer, G. H.; Avilez, I.; Ruíz-Rodríguez, D.; Wasserman, L. H.; Bonanos, Alceste Z.; Guenther, E. W.; Neuhäuser, R.; Levine, S. E.; Bosh, A. S.; Morzinski, Katie M.; Close, Laird; Bailey, Vanessa; Hinz, Phil; Males, Jared R.

2017-08-01

We have characterized the spectroscopic orbit of the TWA 3A binary and provide preliminary families of probable solutions for the TWA 3A visual orbit, as well as for the wide TWA 3A-B orbit. TWA 3 is a hierarchical triple located at 34 pc in the ˜10 Myr old TW Hya association. The wide component separation is 1.″55 the close pair was first identified as a possible binary almost 20 years ago. We initially identified the 35-day period orbital solution using high-resolution infrared spectroscopy that angularly resolved the A and B components. We then refined the preliminary orbit by combining the infrared data with a reanalysis of our high-resolution optical spectroscopy. The orbital period from the combined spectroscopic solution is ˜35 days, the eccentricity is ˜0.63, and the mass ratio is ˜0.84 although this high mass ratio would suggest that optical spectroscopy alone should be sufficient to identify the orbital solution, the presence of the tertiary B component likely introduced confusion in the blended optical spectra. Using millimeter imaging from the literature, we also estimate the inclinations of the stellar orbital planes with respect to the TWA 3A circumbinary disk inclination and find that all three planes are likely misaligned by at least ˜30°. The TWA 3A spectroscopic binary components have spectral types of M4.0 and M4.5; TWA 3B is an M3. We speculate that the system formed as a triple, is bound, and that its properties were shaped by dynamical interactions between the inclined orbits and disk.

The TWA 3 Young Triple System: Orbits, Disks, Evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kellogg, Kendra; Prato, L.; Avilez, I.

2017-08-01

We have characterized the spectroscopic orbit of the TWA 3A binary and provide preliminary families of probable solutions for the TWA 3A visual orbit, as well as for the wide TWA 3A–B orbit. TWA 3 is a hierarchical triple located at 34 pc in the ∼10 Myr old TW Hya association. The wide component separation is 1.″55; the close pair was first identified as a possible binary almost 20 years ago. We initially identified the 35-day period orbital solution using high-resolution infrared spectroscopy that angularly resolved the A and B components. We then refined the preliminary orbit by combining themore » infrared data with a reanalysis of our high-resolution optical spectroscopy. The orbital period from the combined spectroscopic solution is ∼35 days, the eccentricity is ∼0.63, and the mass ratio is ∼0.84; although this high mass ratio would suggest that optical spectroscopy alone should be sufficient to identify the orbital solution, the presence of the tertiary B component likely introduced confusion in the blended optical spectra. Using millimeter imaging from the literature, we also estimate the inclinations of the stellar orbital planes with respect to the TWA 3A circumbinary disk inclination and find that all three planes are likely misaligned by at least ∼30°. The TWA 3A spectroscopic binary components have spectral types of M4.0 and M4.5; TWA 3B is an M3. We speculate that the system formed as a triple, is bound, and that its properties were shaped by dynamical interactions between the inclined orbits and disk.« less

Sensor-triggered sampling to determine instantaneous airborne vapor exposure concentrations.

PubMed

Smith, Philip A; Simmons, Michael K; Toone, Phillip

2018-06-01

It is difficult to measure transient airborne exposure peaks by means of integrated sampling for organic chemical vapors, even with very short-duration sampling. Selection of an appropriate time to measure an exposure peak through integrated sampling is problematic, and short-duration time-weighted average (TWA) values obtained with integrated sampling are not likely to accurately determine actual peak concentrations attained when concentrations fluctuate rapidly. Laboratory analysis for integrated exposure samples is preferred from a certainty standpoint over results derived in the field from a sensor, as a sensor user typically must overcome specificity issues and a number of potential interfering factors to obtain similarly reliable data. However, sensors are currently needed to measure intra-exposure period concentration variations (i.e., exposure peaks). In this article, the digitized signal from a photoionization detector (PID) sensor triggered collection of whole-air samples when toluene or trichloroethylene vapors attained pre-determined levels in a laboratory atmosphere generation system. Analysis by gas chromatography-mass spectrometry of whole-air samples (with both 37 and 80% relative humidity) collected using the triggering mechanism with rapidly increasing vapor concentrations showed good agreement with the triggering set point values. Whole-air samples (80% relative humidity) in canisters demonstrated acceptable 17-day storage recoveries, and acceptable precision and bias were obtained. The ability to determine exceedance of a ceiling or peak exposure standard by laboratory analysis of an instantaneously collected sample, and to simultaneously provide a calibration point to verify the correct operation of a sensor was demonstrated. This latter detail may increase the confidence in reliability of sensor data obtained across an entire exposure period.

A land-use regression model for estimating microenvironmental diesel exposure given multiple addresses from birth through childhood.

PubMed

Ryan, Patrick H; Lemasters, Grace K; Levin, Linda; Burkle, Jeff; Biswas, Pratim; Hu, Shaohua; Grinshpun, Sergey; Reponen, Tiina

2008-10-01

The Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) is a prospective birth cohort whose purpose is to determine if exposure to high levels of diesel exhaust particles (DEP) during early childhood increases the risk for developing allergic diseases. In order to estimate exposure to DEP, a land-use regression (LUR) model was developed using geographic data as independent variables and sampled levels of a marker of DEP as the dependent variable. A continuous wind direction variable was also created. The LUR model predicted 74% of the variability in sampled values with four variables: wind direction, length of bus routes within 300 m of the sample site, a measure of truck intensity within 300 m of the sampling site, and elevation. The LUR model was subsequently applied to all locations where the child had spent more than eight hours per week from through age three. A time-weighted average (TWA) microenvironmental exposure estimate was derived for four time periods: 0-6 months, 7-12 months, 13-24 months, 25-36 months. By age two, one third of the children were spending significant time at locations other than home and by 36 months, 39% of the children had changed their residential addresses. The mean cumulative DEP exposure estimate increased from age 6 to 36 months from 70 to 414 microg/m3-days. Findings indicate that using birth addresses to estimate a child's exposure may result in exposure misclassification for some children who spend a significant amount of time at a location with high exposure to DEP.

A population-based exposure assessment methodology for carbon monoxide: Development of a carbon monoxide passive sampler and occupational dosimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apte, Michael G.

Two devices, an occupational carbon monoxide (CO) dosimeter (LOCD), and an indoor air quality (IAQ) passive sampler were developed for use in population-based CO exposure assessment studies. CO exposure is a serious public health problem in the U.S., causing both morbidity and mortality (lifetime mortality risk approximately 10{sup -4}). Sparse data from population-based CO exposure assessments indicate that approximately 10% of the U.S. population is exposed to CO above the national ambient air quality standard. No CO exposure measurement technology is presently available for affordable population-based CO exposure assessment studies. The LOCD and IAQ Passive Sampler were tested in themore » laboratory and field. The palladium-molybdenum based CO sensor was designed into a compact diffusion tube sampler that can be worn. Time-weighted-average (TWA) CO exposure of the device is quantified by a simple spectrophotometric measurement. The LOCD and IAQ Passive Sampler were tested over an exposure range of 40 to 700 ppm-hours and 200 to 4200 ppm-hours, respectively. Both devices were capable of measuring precisely (relative standard deviation <20%), with low bias (<10%). The LOCD was screened for interferences by temperature, humidity, and organic and inorganic gases. Temperature effects were small in the range of 10°C to 30°C. Humidity effects were low between 20% and 90% RH. Ethylene (200 ppm) caused a positive interference and nitric oxide (50 ppm) caused a negative response without the presence of CO but not with CO.« less

Assessment of airborne asbestos exposure during the servicing and handling of automobile asbestos-containing gaskets.

PubMed

Blake, Charles L; Dotson, G Scott; Harbison, Raymond D

2006-07-01

Five test sessions were conducted to assess asbestos exposure during the removal or installation of asbestos-containing gaskets on vehicles. All testing took place within an operative automotive repair facility involving passenger cars and a pickup truck ranging in vintage from late 1960s through 1970s. A professional mechanic performed all shop work including engine disassembly and reassembly, gasket manipulation and parts cleaning. Bulk sample analysis of removed gaskets through polarized light microscopy (PLM) revealed asbestos fiber concentrations ranging between 0 and 75%. Personal and area air samples were collected and analyzed using National Institute of Occupational Safety Health (NIOSH) methods 7400 [phase contrast microscopy (PCM)] and 7402 [transmission electron microscopy (TEM)]. Among all air samples collected, approximately 21% (n = 11) contained chrysotile fibers. The mean PCM and phase contrast microscopy equivalent (PCME) 8-h time weighted average (TWA) concentrations for these samples were 0.0031 fibers/cubic centimeters (f/cc) and 0.0017 f/cc, respectively. Based on these findings, automobile mechanics who worked with asbestos-containing gaskets may have been exposed to concentrations of airborne asbestos concentrations approximately 100 times lower than the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.1 f/cc.

Occupational exposure to hydrogen cyanide during large-scale cassava processing, in Alagoas State, Brazil.

PubMed

Zacarias, Cyro Hauaji; Esteban, Claudia; Rodrigues, Gilson Lucio; Nascimento, Elizabeth de Souza

2017-07-27

The cassava roots used for flour production contain high amounts of cyanogenic glycosides and are, therefore, potential hydrogen cyanide (HCN) releasers. This fact is the cause of an increasing health concern in the sector of cassava processing. Brazilian workers engaged in the flour production may be chronically exposed to HCN in levels above the safety limits. This hypothesis is based on the drastic reduction in cyanide content of cassava roots during a traditional Brazilian method of processing and in the physical properties of the compound, which makes it very susceptible to volatilization and air contamination. As an attempt to explore this issue, HCN exposure in Brazilian "flour houses" was evaluated in this study through environmental and biological monitoring. Four flour houses placed in Alagoas State, Brazil, were investigated. The results indicated that the cassava processors are chronically exposed to HCN at average levels between 0.464 and 3.328mg/m3 (TWA), in the work environment. This range is below the TLV-C of 5mg/m3 but not below the Action Level of 2.5mg/m3. These data may be interpreted as a possible risk to susceptible individuals. Additionally, the biological monitoring indicated a high cyanide exposure in the population study, considering urinary thiocyanate (SCN-) levels.

Lead and methylene chloride exposures among automotive repair technicians.

PubMed

Enander, Richard T; Cohen, Howard J; Gute, David M; Brown, Linfield C; Desmaris, Anne Marie C; Missaghian, Richard

2004-02-01

Potential exposures among repair technicians engaged in vehicle resurfacing operations prior to spray painting have not been thoroughly characterized. Environmental and personal air monitoring conducted in the State of Rhode Island have shown that automotive repair technicians may be exposed to metal particulates in sanding dust and methylene chloride vapors during vehicle paint removal operations. Hand wipe samples demonstrated that metals in sanding dust adhered to the hands of workers throughout the duration of the work day and were available for incidental ingestion from the handling of food/nonfood items and hand-to-mouth contact. A blood lead (PbB) screening effort among 21 workers at 2 facilities showed that 4 non-/less-exposed workers had mean PbB levels at the U.S. geometric mean of 2.8 microg/dL, while 2 out of 9 (22%) dedicated vehicle repair technicians had PbB levels at or above 30 microg Pb/dL whole blood--the level for potential adverse reproductive effects. Methylene chloride exposures were also found to exceed the Occupational Safety and Health Administrations (OSHA) 8-hr time-weighted average (TWA) action level and permissible exposure limit (PEL) in a limited number of samples (120 and 26 ppm, integrated work shift samples). Our findings suggest that thousands of professional technicians and vocational high school students may be at increased risk of adverse reproductive and/or other systemic effects.

Monitoring of 45 pesticides in Lebanese surface water using Polar Organic Chemical Integrative Sampler (POCIS)

NASA Astrophysics Data System (ADS)

Aisha, Al Ashi; Hneine, Wael; Mokh, Samia; Devier, Marie-Hélène; Budzinski, Hélèn; Jaber, Farouk

2017-09-01

The aim of this study is to assess the dissolved concentration of 45 pesticides in the surface waters of the Lebanese Republic using Polar Organic Chemical Integrative Sampler "POCIS". All of the sampling sites are located in the major agricultural land areas in Lebanon. POCIS (n = 3) were deployed at Ibrahim River, Qaraoun Lake and Hasbani River for a duration of 14 days. The total concentration of pesticides ranged from not detected (nd) to 137.66 ng.L-1. Chlorpyrifos, DDE-pp, diazinon and Fenpropathrin were the most abundant compounds. Qaraoun Lake and Hasbani River were found to be more polluted than Ibrahim River, since they receive large amounts of waste water derived from nearby agricultural lands and they had the lowest dilution factor. The aqueous average concentration of the target compounds were estimated using sampling rates obtained from the literature. Comparison between Time Weighed Average concentrations "TWA" using POCIS and spot sampling is presented. Results showed that POCIS TWA concentrations are in agreement with spot sampling concentrations for Ibrahim and Hasbani Rivers. The toxicity of the major detected pesticides on three representative aquatic species ( Daphnia magna, Scenedesmus quadricauda and Oncorhynchus mykiss) is also reported.

SEARCHING FOR YOUNG M DWARFS WITH GALEX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shkolnik, Evgenya L.; Weinberger, Alycia J.; Liu, Michael C.

2011-01-20

The census of young moving groups in the solar neighborhood is significantly incomplete in the low-mass regime. We have developed a new selection process to find these missing members based on the Galaxy Evolution Explorer (GALEX) All-Sky Imaging Survey (AIS). For stars with spectral types {approx}>K5 (R - J {approx}> 1.5) and younger than {approx}300 Myr, we show that near-UV (NUV) and far-UV (FUV) emission is greatly enhanced above the quiescent photosphere, analogous to the enhanced X-ray emission of young low-mass stars seen by ROSAT but detectable to much larger distances with GALEX. By combining GALEX data with optical (HSTmore » Guide Star Catalog) and near-IR (2MASS) photometry, we identified an initial sample of 34 young M dwarf candidates in a 1000 deg{sup 2} region around the {approx}10 Myr TW Hydra Association (TWA). Low-resolution spectroscopy of 30 of these found 16 which had H{alpha} in emission, which were then followed up at high resolution to search for spectroscopic evidence of youth and to measure their radial velocities. Four objects have low surface gravities, photometric distances and space motions consistent with TWA, but the non-detection of Li indicates that they may be too old to belong to this moving group. One object (M3.5, 93 {+-} 19 pc) appears to be the first known accreting low-mass member of the {approx}15 Myr Lower Centaurus Crux OB association. Two objects exhibit all the characteristics of the known TWA members, and thus we designate them as TWA 31 (M4.2, 110 {+-} 11 pc) and TWA 32 (M6.3, 53 {+-} 5 pc). TWA 31 shows extremely broad (447 km s{sup -1}) H{alpha} emission, making it the sixth member of TWA found to have ongoing accretion. TWA 32 is resolved into a 0.''6 binary in Keck laser guide star adaptive optics imaging. Our search should be sensitive down to spectral types of at least M4-M5 in TWA and thus the small numbers of new member is puzzling. This might indicate TWA has an atypical mass function or that the presence of lithium absorption may be too restrictive a criteria for selecting young low-mass stars.« less

Exposures to jet fuel and benzene during aircraft fuel tank repair in the U.S. Air Force.

PubMed

Carlton, G N; Smith, L B

2000-06-01

Jet fuel and benzene vapor exposures were measured during aircraft fuel tank entry and repair at twelve U.S. Air Force bases. Breathing zone samples were collected on the fuel workers who performed the repair. In addition, instantaneous samples were taken at various points during the procedures with SUMMA canisters and subsequent analysis by mass spectrometry. The highest eight-hour time-weighted average (TWA) fuel exposure found was 1304 mg/m3; the highest 15-minute short-term exposure was 10,295 mg/m3. The results indicate workers who repair fuel tanks containing explosion suppression foam have a significantly higher exposure to jet fuel as compared to workers who repair tanks without foam (p < 0.001). It is assumed these elevations result from the tendency for fuel, absorbed by the foam, to volatilize during the foam removal process. Fuel tanks that allow flow-through ventilation during repair resulted in lower exposures compared to those tanks that have only one access port and, as a result, cannot be ventilated efficiently. The instantaneous sampling results confirm that benzene exposures occur during fuel tank repair; levels up to 49.1 mg/m3 were found inside the tanks during the repairs. As with jet fuel, these elevated benzene concentrations were more likely to occur in foamed tanks. The high temperatures associated with fuel tank repair, along with the requirement to wear vapor-permeable cotton coveralls for fire reasons, could result in an increase in the benzene body burden of tank entrants.

Beryllium health effects in the era of the beryllium lymphocyte proliferation test.

PubMed

Maier, L A

2001-05-01

The beryllium lymphocyte proliferation test (BeLPT) has revolutionized our approach to the diagnosis, screening, and surveillance of beryllium health effects. Based on the development of a beryllium-specific cell-mediated immune response, the BeLPT has allowed us to define early health effects of beryllium, including beryllium sensitization (BeS), and chronic beryllium disease (CBD) at a subclinical stage. The use of this test as a screening tool has improved our understanding of these health effects. From a number of studies it is apparent that BeS precedes CBD and develops after as little as 9 weeks of beryllium exposure. CBD occurs within 3 months and up to 30 years after initial beryllium exposure. Exposure-response variables have been associated with BeS/CBD, including work as a machinist, chemical or metallurgical operator, laboratory technician, work in ceramics or beryllium metal production, and years of beryllium exposure. Recent studies have found BeS and CBD in workplaces in which the majority of exposures were below the 2 microg/m3 OSHA time-weighted average (TWA). Ideally, the BeLPT would be used in surveillance aimed at defining other risk-related processes, determining exposure variables which predict BeS and CBD, and defining the exposure level below which beryllium health effects do not occur. Unfortunately, the BeLPT can result in false negative tests and still requires an invasive procedure, a bronchoscopy, for the definitive diagnosis of CBD. Thus, research is needed to establish new tests to be used alone or in conjunction with the BeLPT to improve our ability to detect early beryllium health effects.

Characteristics of Occupational Exposure to Benzene during Turnaround in the Petrochemical Industries.

PubMed

Chung, Eun-Kyo; Shin, Jung-Ah; Lee, Byung-Kyu; Kwon, Jiwoon; Lee, Naroo; Chung, Kwang-Jae; Lee, Jong-Han; Lee, In-Seop; Kang, Seong-Kyu; Jang, Jae-Kil

2010-09-01

The level of benzene exposure in the petrochemical industry during regular operation has been well established, but not in turnaround (TA), where high exposure may occur. In this study, the characteristics of occupational exposure to benzene during TA in the petrochemical companies were investigated in order to determine the best management strategies and improve the working environment. This was accomplished by evaluating the exposure level for the workers working in environments where benzene was being produced or used as an ingredient during the unit process. From 2003 to 2008, a total of 705 workers in three petrochemical companies in Korea were studied. Long- and short-term (< 1 hr) samples were taken during TAs. TA was classified into three stages: shut-down, maintenance and start-up. All works were classified into 12 occupation categories. The long-term geometric mean (GM) benzene exposure level was 0.025 (5.82) ppm (0.005-42.120 ppm) and the short-term exposure concentration during TA was 0.020 (17.42) ppm (0.005-61.855 ppm). The proportions of TA samples exceeding the time-weighted average, occupational exposure level (TWA-OEL in Korea, 1 ppm) and the short-term exposure limit (STEL-OEL, 5 ppm) were 4.1% (20 samples of 488) and 6.0% (13 samples of 217), respectively. The results for the benzene exposure levels and the rates of exceeding the OEL were both statistically significant (p < 0.05). Among the 12 job categories of petrochemical workers, mechanical engineers, plumbers, welders, fieldman and scaffolding workers exhibited long-term samples that exceeded the OEL of benzene, and the rate of exceeding the OEL was statistically significant for the first two occupations (p < 0.05). These findings suggest that the periodic work environment must be assessed during non-routine works such as TA.

Variations of melatonin and stress hormones under extended shifts and radiofrequency electromagnetic radiation.

PubMed

Vangelova, Katia Koicheva; Israel, Mishel Salvador

2005-01-01

We studied the time-of-day variations in urinary levels of 6-sulphatoxy-melatonin and three stress hormones in operators working fast-rotating extended shifts under radiofrequency electromagnetic radiation (EMR). The excretion rate of the hormones was monitored by radioimmunoassay and spectrofluorimetry at 4-hour intervals in a group of 36 male operators comprising 12 broadcasting station operators, 12 TV station operators, and a control group of 12 satellite station operators. Measuring the time-weighted average (TWA) of EMR exposure revealed a high-level of exposure in broadcasting station operators (TWAmean= 3.10 microW/ cm2, TWAmax = 137.00 microW/cm2), a low-level in TV station operators (TWAmean = 1.89 microW/cm2, TWAmax = 5.24 microW/cm2), and a very low level in satellite station operators. The differences among the groups remained the same after confounding factors were taken into account. Radiofrequency EMR had no effect on the typical diurnal pattern of 6-sulphatoxymelatonin. High-level radiofrequency EMR exposure significantly increased the excretion rates of cortisol (p < 0.001), adrenaline (p = 0.028), and noradrenaline (p < 0.000), whereas changes under low-level exposure did not reach significance. The 24-hour excretion of cortisol and noradrenaline correlated with TWAmean and TWAmax. In conclusion, the excretion of 6-sulphatoxymelatonin retained a typical diurnal pattern under fast-rotating extended shifts and radiofrequency EMR, but showed an exposure-effect relation with stress hormones.

Lead exposure and blood pressure among workers in diverse industrial plants in Kenya.

PubMed

Were, Faridah H; Moturi, M Charles; Gottesfeld, P; Wafula, Godfrey A; Kamau, Geoffrey N; Shiundu, Paul M

2014-01-01

The study evaluated airborne exposures and blood lead (BPb) levels in 233 production workers at six diverse industrial plants in Kenya. Blood and personal breathing zone air samples were collected and analyzed for lead (Pb) using atomic absorption spectroscopy. Blood pressure (BP) levels were measured using a standard mercury sphygmomanometer. The results indicated mean airborne Pb levels ± standard deviation (SD) as follows: 183.2 ± 53.6 μg/m(3) in battery recycling, 133.5 ± 39.6 μg/m(3) in battery manufacturing, 126.2 ± 39.9 μg/m(3) in scrap metal welding, 76.3 ± 33.2 μg/m(3) in paint manufacturing, 27.3 ± 12.1 μg/m(3) in a leather manufacturing, and 5.5 ± 3.6 μg/m(3) in a pharmaceutical plant. The mean airborne Pb levels exceeded the U.S. Occupational Safety and Health Administration (OSHA) 8-hr time-weighted average (TWA) permissible exposure limit (PEL) for Pb of 50 μg/m(3) in the battery manufacturing, battery recycling, welding, and paint manufacturing plants. Similarly, mean BPb concentrations exceeded the American Conference of Governmental Industrial Hygienists (ACGIH®) biological exposure index (BEI) for Pb of 30 μg/dl. A significant positive association was observed between BPb and breathing zone air Pb (R(2) = 0.73, P < 0.001). Approximately 30% of the production workers (N = 233) were in the hypertensive range with an average systolic and diastolic blood pressure (BP) of 134.7 ± 12.7 mmHg and 86.4 ± 8.9 mmHg, respectively. In the multivariate regression analysis, age, duration of work, airborne Pb and BPb levels were significantly associated (P < 0.05) with a change in BP. We recommend improved engineering controls, work practices, and personal hygiene to reduce Pb exposures. In addition, workers should undergo comprehensive medical surveillance to include BPb and BP testing, and airborne Pb assessments in all industries with significant lead exposures.

IDENTIFYING NEARBY, YOUNG, LATE-TYPE STARS BY MEANS OF THEIR CIRCUMSTELLAR DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneider, Adam; Song, Inseok; Melis, Carl

2012-10-01

It has recently been shown that a significant fraction of late-type members of nearby, very young associations (age {approx}<10 Myr) display excess emission at mid-IR wavelengths indicative of dusty circumstellar disks. We demonstrate that the detection of mid-IR excess emission can be utilized to identify new nearby, young, late-type stars including two definite new members ('TWA 33' and 'TWA 34') of the TW Hydrae Association (TWA). Both new TWA members display mid-IR excess emission in the Wide-field Infrared Survey Explorer catalog and they show proper motion and youthful spectroscopic characteristics-namely, H{alpha} emission, strong lithium absorption, and low surface gravity featuresmore » consistent with known TWA members. We also detect mid-IR excess-the first unambiguous evidence of a dusty circumstellar disk-around a previously identified UV-bright, young, accreting star (2M1337) that is a likely member of the Lower-Centaurus Crux region of the Scorpius-Centaurus Complex.« less

Compact Single-Layer Traveling-Wave Antenna DesignUsing Metamaterial Transmission Lines

NASA Astrophysics Data System (ADS)

Alibakhshikenari, Mohammad; Virdee, Bal Singh; Limiti, Ernesto

2017-12-01

This paper presents a single-layer traveling-wave antenna (TWA) that is based on composite right/left-handed (CRLH)-metamaterial (MTM) transmission line (TL) structure, which is implemented by using a combination of interdigital capacitors and dual-spiral inductive slots. By embedding dual-spiral inductive slots inside the CRLH MTM-TL results in a compact TWA. Dimensions of the proposed CRLH MTM-TL TWA is 21.5 × 30.0 mm2 or 0.372λ0 × 0.520λ0 at 5.2 GHz (center frequency). The fabricated TWA operates over 1.8-8.6 GHz with a fractional bandwidth greater than 120%, and it exhibits a peak gain and radiation efficiency of 4.2 dBi and 81%, respectively, at 5 GHz. By avoiding the use of lumped components, via-holes or defected ground structures, the proposed TWA design is economic for mass production as well as easy to integrate with wireless communication systems.

Low-voltage harmonic multiplying gyrotron traveling-wave amplifier in G band

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeh, Y. S.; Guo, Y. W.; Kao, B. H.

Harmonic multiplying operation in a gyrotron traveling-wave amplifier (gyro-TWA) permits for magnetic field reduction and frequency multiplication. Lowering a beam voltage is an important step toward miniaturization of a harmonic multiplying gyro-TWA. However, the additional degree of freedom that is provided by the multitude cyclotron harmonics in a low-voltage harmonic multiplying gyro-TWA still easily generates various competing modes. An improved mode-selective circuit, using circular waveguides with various radii, can provide the rejection points within the frequency range to suppress competing modes. Simulated results reveal that the mode-selective circuit can provide an attenuation of more than 14 dB to suppress the competingmore » modes. Furthermore, the performance of the gyro-TWA is analyzed for studying the sensitivity of the saturated output power and full width at half maximum bandwidth of the gyro-TWA to the beam voltage and the magnetic field. A stable low-voltage harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 24 kW at 200.4 GHz, corresponding to a saturated gain of 56 dB at an interaction efficiency of 20%. The full width at half maximum bandwidth is 3.0 GHz.« less

Effect of water velocity on the uptake of polychlorinated biphenyls (PCBs) by silicone rubber (SR) and low-density polyethylene (LDPE) passive samplers: an assessment of the efficiency of performance reference compounds (PRCs) in river-like flow conditions.

PubMed

Estoppey, Nicolas; Schopfer, Adrien; Omlin, Julien; Esseiva, Pierre; Vermeirssen, Etiënne L M; Delémont, Olivier; De Alencastro, Luiz F

2014-11-15

One aim of this study is to determine the impact of water velocity on the uptake of indicator polychlorinated biphenyls (iPCBs) by silicone rubber (SR) and low-density polyethylene (LDPE) passive samplers. A second aim is to assess the efficiency of performance reference compounds (PRCs) to correct for the impact of water velocity. SR and LDPE samplers were spiked with 11 or 12 PRCs and exposed for 6 weeks to four different velocities (in the range of 1.6 to 37.7 cm s(-1)) in river-like flow conditions using a channel system supplied with river water. A relationship between velocity and the uptake was found for each iPCB and enables to determine expected changes in the uptake due to velocity variations. For both samplers, velocity increases from 2 to 10 cm s(-1), 30 cm s(-1) (interpolated data) and 100 cm s(-1) (extrapolated data) lead to increases of the uptake which do not exceed a factor of 2, 3 and 4.5, respectively. Results also showed that the influence of velocity decreased with increasing the octanol-water coefficient partition (log K(ow)) of iPCBs when SR is used whereas the opposite effect was observed for LDPE. Time-weighted average (TWA) concentrations of iPCBs in water were calculated from iPCB uptake and PRC release. These calculations were performed using either a single PRC or all the PRCs. The efficiency of PRCs to correct the impact of velocity was assessed by comparing the TWA concentrations obtained at the four tested velocities. For SR, a good agreement was found among the four TWA concentrations with both methods (average RSD<10%). Also for LDPE, PRCs offered a good correction of the impact of water velocity (average RSD of about 10 to 20%). These results contribute to the process of acceptance of passive sampling in routine regulatory monitoring programs. Copyright © 2014 Elsevier B.V. All rights reserved.

Searching for Young M Dwarfs with GALEX

NASA Astrophysics Data System (ADS)

Shkolnik, Evgenya L.; Liu, Michael C.; Reid, I. Neill; Dupuy, Trent; Weinberger, Alycia J.

2011-01-01

The census of young moving groups in the solar neighborhood is significantly incomplete in the low-mass regime. We have developed a new selection process to find these missing members based on the Galaxy Evolution Explorer (GALEX) All-Sky Imaging Survey (AIS). For stars with spectral types gsimK5 (R - J >~ 1.5) and younger than ≈300 Myr, we show that near-UV (NUV) and far-UV (FUV) emission is greatly enhanced above the quiescent photosphere, analogous to the enhanced X-ray emission of young low-mass stars seen by ROSAT but detectable to much larger distances with GALEX. By combining GALEX data with optical (HST Guide Star Catalog) and near-IR (2MASS) photometry, we identified an initial sample of 34 young M dwarf candidates in a 1000 deg2 region around the ≈10 Myr TW Hydra Association (TWA). Low-resolution spectroscopy of 30 of these found 16 which had Hα in emission, which were then followed up at high resolution to search for spectroscopic evidence of youth and to measure their radial velocities. Four objects have low surface gravities, photometric distances and space motions consistent with TWA, but the non-detection of Li indicates that they may be too old to belong to this moving group. One object (M3.5, 93 ± 19 pc) appears to be the first known accreting low-mass member of the ≈15 Myr Lower Centaurus Crux OB association. Two objects exhibit all the characteristics of the known TWA members, and thus we designate them as TWA 31 (M4.2, 110 ± 11 pc) and TWA 32 (M6.3, 53 ± 5 pc). TWA 31 shows extremely broad (447 km s-1) Hα emission, making it the sixth member of TWA found to have ongoing accretion. TWA 32 is resolved into a 0farcs6 binary in Keck laser guide star adaptive optics imaging. Our search should be sensitive down to spectral types of at least M4-M5 in TWA and thus the small numbers of new member is puzzling. This might indicate TWA has an atypical mass function or that the presence of lithium absorption may be too restrictive a criteria for selecting young low-mass stars. This paper is based on data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile, the Keck II telescope, and the GALEX, 2MASS, and HST/GSC v2.3 photometric catalogs. GALEX is operated for NASA by the California Institute of Technology under NASA contract NAS5-98034.

A Gaia DR2 Confirmation that 2MASS J12074836–3900043 is a Member of the TW HYA Association

NASA Astrophysics Data System (ADS)

Gagné, Jonathan; Gonzales, Eileen C.; Faherty, Jacqueline K.

2018-05-01

We use new data from Gaia DR2 to confirm that the young L1 $\\gamma$ candidate member of the TW Hya association (TWA) is now a bona fide member with a model-dependent mass estimate of ~15 $M_{Jup}$. The ambiguous M9 $\\gamma$ candidate member 2MASS J12474428---3816464 also gets a higher Bayesian membership probability for TWA membership as a result of Gaia DR2 data and a new radial velocity measurement, but it remains unclear whether it is a true member of TWA or if it is an unrelated young interloper, because it is separated by 4.6 km/s from the locus of TWA members in UVW space.

Assessment and evaluation of noise controls on roof bolting equipment and a method for predicting sound pressure levels in underground coal mining

NASA Astrophysics Data System (ADS)

Matetic, Rudy J.

Over-exposure to noise remains a widespread and serious health hazard in the U.S. mining industries despite 25 years of regulation. Every day, 80% of the nation's miners go to work in an environment where the time weighted average (TWA) noise level exceeds 85 dBA and more than 25% of the miners are exposed to a TWA noise level that exceeds 90 dBA, the permissible exposure limit (PEL). Additionally, MSHA coal noise sample data collected from 2000 to 2002 show that 65% of the equipment whose operators exceeded 100% noise dosage comprise only seven different types of machines; auger miners, bulldozers, continuous miners, front end loaders, roof bolters, shuttle cars (electric), and trucks. In addition, the MSHA data indicate that the roof bolter is third among all the equipment and second among equipment in underground coal whose operators exceed 100% dosage. A research program was implemented to: (1) determine, characterize and to measure sound power levels radiated by a roof bolting machine during differing drilling configurations (thrust, rotational speed, penetration rate, etc.) and utilizing differing types of drilling methods in high compressive strength rock media (>20,000 psi). The research approach characterized the sound power level results from laboratory testing and provided the mining industry with empirical data relative to utilizing differing noise control technologies (drilling configurations and types of drilling methods) in reducing sound power level emissions on a roof bolting machine; (2) distinguish and correlate the empirical data into one, statistically valid, equation, in which, provided the mining industry with a tool to predict overall sound power levels of a roof bolting machine given any type of drilling configuration and drilling method utilized in industry; (3) provided the mining industry with several approaches to predict or determine sound pressure levels in an underground coal mine utilizing laboratory test results from a roof bolting machine and (4) described a method for determining an operators' noise dosage of a roof bolting machine utilizing predicted or determined sound pressure levels.

Dependency of exercise-induced T-wave alternans predictive power for the occurrence of ventricular arrhythmias from heart rate.

PubMed

Burattini, Laura; Man, Sumche; Fioretti, Sandro; Di Nardo, Francesco; Swenne, Cees A

2015-07-01

T-wave alternans (TWA) is a noninvasive index of risk for the occurrence of ventricular arrhythmias. It is known that TWA amplitude (TWAA) increases with heart rate (HR) but how the TWA predictive power varies with HR remains unknown. Thus, the aim of this study was to evaluate the dependency of exercise-induced TWA predictive power for the occurrence of ventricular arrhythmias from HR. TWA was identified using our HR adaptive match filter in exercise ECGs from 248 patients with implanted cardiac defibrillator (ICD), of which 72 developed ventricular tachycardia and/or fibrillation during the 4 year follow-up (ICD_Cases) and 176 did not (ICD_Controls). TWA predictive power was evaluated at HRs from 80 to 120 bpm by computing the area under the receiver operating characteristic curve (AUC) obtained using the maximum TWAA (maxTWAA) and the TWAA ratio (TWAAratio; i.e., the ratio between TWAA at a specific HR and at 80 bpm). TWAA increased with HR. At 80 bpm maxTWAA was lower than at 120 bpm in both ICD_Cases (22 μV vs 41 μV; P < 10(-2) ) and ICD_ Controls (16 μV vs 36 μV; P < 10(-4) ). However, only at 80 bpm ICD_Cases showed significantly higher maxTWAA than ICD_Controls (AUC = 0.6486; P = 0.0080). TWAAratio was higher in ICD_Controls than ICD_Cases for all HR but 120 bpm, and its predictive power was maximum at 115 bpm (AUC = 0.6914; P < 0.05). Exercise-induced TWA predictive power for the occurrence of ventricular arrhythmias, quantified using both maxTWAA and TWAAratio, was higher at low rather than at high HR. © 2014 Wiley Periodicals, Inc.

Gas and dust in the TW Hydrae association as seen by the Herschel Space Observatory

NASA Astrophysics Data System (ADS)

Riviere-Marichalar, P.; Pinte, C.; Barrado, D.; Thi, W. F.; Eiroa, C.; Kamp, I.; Montesinos, B.; Donaldson, J.; Augereau, J. C.; Huélamo, N.; Roberge, A.; Ardila, D.; Sandell, G.; Williams, J. P.; Dent, W. R. F.; Menard, F.; Lillo-Box, J.; Duchêne, G.

2013-07-01

Context. Circumstellar discs are the places where planets form, therefore knowledge of their evolution is crucial for our understanding of planet formation. The Herschel Space Observatory is providing valuable data for studying disc systems, thanks to its sensitivity and wavelength coverage. This paper is one of several devoted to analysing and modelling Herschel-PACS observations of various young stellar associations from the GASPS open time key programme. Aims: The aim of this paper is to elucidate the gas and dust properties of circumstellar discs in the ~10 Myr TW Hya association (TWA) using new far-infrared (IR) imaging and spectroscopy from Herschel-PACS. Methods: We obtained far-IR photometric data at 70, 100, and 160 μm of 14 TWA members; spectroscopic observations centred on the [OI] line at 63.18 μm were also obtained for 9 of the 14. The new photometry for each star was incorporated into its full spectral energy distribution. Results: We detected excess IR emission that is characteristic of circumstellar discs from five TWA members, and computed upper limits for another nine. Two TWA members (TWA 01 and TWA 04B) also show [OI] emission at 63.18 μm. Discs in the TWA association display a variety of properties, with a wide range of dust masses and inner radii, based on modified blackbody modelling. Both transitional and debris discs are found in the sample. Models for sources with a detected IR excess give dust masses in the range from ~0.15 M⊕ to ~63 M⊕. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

A portable data-logging system for industrial hygiene personal chlorine monitoring.

PubMed

Langhorst, M L; Illes, S P

1986-02-01

The combination of suitable portable sensors or instruments with small microprocessor-based data-logger units has made it possible to obtain detailed monitoring data for many health and environmental applications. Following data acquisition in field use, the logged data may be transferred to a desk-top personal computer for complete flexibility in manipulation of data and formating of results. A system has been assembled from commercial components and demonstrated for chlorine personal monitoring applications. The system consists of personal chlorine sensors, a Metrosonics data-logger and reader unit, and an Apple II Plus personal computer. The computer software was developed to handle sensor calibration, data evaluation and reduction, report formating and long-term storage of raw data on a disk. This system makes it possible to generate time-concentration profiles, evaluate dose above a threshold, quantitate short-term excursions and summarize time-weighted average (TWA) results. Field data from plant trials demonstrated feasibility of use, ruggedness and reliability. No significant differences were found between the time-weighted average chlorine concentrations determined by the sensor/logger system and two other methods: the sulfamic acid bubbler reference method and the 3M Poroplastic diffusional dosimeter. The sensor/data-logger system, however, provided far more information than the other two methods in terms of peak excursions, TWAs and exposure doses. For industrial hygiene applications, the system allows better definition of employee exposures, particularly for chemicals with acute as well as chronic health effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory Symptoms and Pulmonary Function Tests among Galvanized Workers Exposed To Zinc Oxide.

PubMed

Aminian, Omid; Zeinodin, Hamidreza; Sadeghniiat-Haghighi, Khosro; Izadi, Nazanin

2015-01-01

Galvanization is the process of coating steel or cast iron pieces with a thin layer of zinc allowing protection against corrosion. One of the important hazards in this industry is exposure to zinc compounds specially zinc oxide fumes and dusts. In this study, we evaluated chronic effects of zinc oxide on the respiratory tract of galvanizers. Overall, 188 workers were selected from Arak galvanization plant in 2012, 71 galvanizers as exposed group and 117 workers from other departments of plants as control group. Information was collected using American Thoracic Society (ATS) standard questionnaire, physical examination and demographic data sheet. Pulmonary function tests were measured for all subjects. Exposure assessment was done with NIOSH 7030 method. The Personal Breathing Zone (PBZ) air sampling results for zinc ranged from 6.61 to 8.25 mg/m³ above the permissible levels (Time weighted average; TWA:2 mg/m³). The prevalence of the respiratory symptoms such as dyspnea, throat and nose irritation in the exposed group was significantly (P<0.01) more than the control group. Decreasing in average percent in all spirometric parameters were seen in the galvanizers who exposed to zinc oxide fumes and dusts. The prevalence of obstructive respiratory disease was significantly (P=0.034) higher in the exposed group. High workplace zinc levels are associated with an increase in respiratory morbidity in galvanizers. Therefore administrators should evaluate these workers with periodic medical examinations and implement respiratory protection program in the working areas.

Analysis of trace contaminants in hot gas streams using time-weighted average solid-phase microextraction: proof of concept.

PubMed

Woolcock, Patrick J; Koziel, Jacek A; Cai, Lingshuang; Johnston, Patrick A; Brown, Robert C

2013-03-15

Time-weighted average (TWA) passive sampling using solid-phase microextraction (SPME) and gas chromatography was investigated as a new method of collecting, identifying and quantifying contaminants in process gas streams. Unlike previous TWA-SPME techniques using the retracted fiber configuration (fiber within needle) to monitor ambient conditions or relatively stagnant gases, this method was developed for fast-moving process gas streams at temperatures approaching 300 °C. The goal was to develop a consistent and reliable method of analyzing low concentrations of contaminants in hot gas streams without performing time-consuming exhaustive extraction with a slipstream. This work in particular aims to quantify trace tar compounds found in a syngas stream generated from biomass gasification. This paper evaluates the concept of retracted SPME at high temperatures by testing the three essential requirements for TWA passive sampling: (1) zero-sink assumption, (2) consistent and reliable response by the sampling device to changing concentrations, and (3) equal concentrations in the bulk gas stream relative to the face of the fiber syringe opening. Results indicated the method can accurately predict gas stream concentrations at elevated temperatures. Evidence was also discovered to validate the existence of a second boundary layer within the fiber during the adsorption/absorption process. This limits the technique to operating within reasonable mass loadings and loading rates, established by appropriate sampling depths and times for concentrations of interest. A limit of quantification for the benzene model tar system was estimated at 0.02 g m(-3) (8 ppm) with a limit of detection of 0.5 mg m(-3) (200 ppb). Using the appropriate conditions, the technique was applied to a pilot-scale fluidized-bed gasifier to verify its feasibility. Results from this test were in good agreement with literature and prior pilot plant operation, indicating the new method can measure low concentrations of tar in gasification streams. Copyright © 2013 Elsevier B.V. All rights reserved.

G-band harmonic multiplying gyrotron traveling-wave amplifier with a mode-selective circuit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeh, Y. S.; Chen, Chang-Hong; Wang, Z. W.

Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) permit for magnetic field reduction and frequency multiplication. A high-order-mode harmonic multiplying gyro-TWA with large circuit dimensions and low ohmic loss can achieve a high average power. By amplifying a fundamental harmonic TE{sub 01} drive wave, the second harmonic component of the beam current initiates a TE{sub 02} wave to be amplified. Wall losses can suppress some competing modes because they act as an effective sink of the energy of the modes. However, such wall losses do not suppress all competing modes as the fields are contracted in the copper section in the gyro-TWA.more » An improved mode-selective circuit, using circular waveguides with the specified radii, can provide the rejection points within the frequency range to suppress the competing modes. The simulated results reveal that the mode-selective circuit can provide an attenuation of more than 10 dB to suppress the competing modes (TE{sub 21}, TE{sub 51}, TE{sub 22}, and TE{sub 03}). A G-band second harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 50 kW at 198.8 GHz, corresponding to a saturated gain of 55 dB at an interaction efficiency of 10%. The full width at half maximum bandwidth is 5 GHz.« less

Evaluation of take-home exposure and risk associated with the handling of clothing contaminated with chrysotile asbestos.

PubMed

Sahmel, J; Barlow, C A; Simmons, B; Gaffney, S H; Avens, H J; Madl, A K; Henshaw, J; Lee, R J; Van Orden, D; Sanchez, M; Zock, M; Paustenbach, D J

2014-08-01

The potential for para-occupational (or take-home) exposures from contaminated clothing has been recognized for the past 60 years. To better characterize the take-home asbestos exposure pathway, a study was performed to measure the relationship between airborne chrysotile concentrations in the workplace, the contamination of work clothing, and take-home exposures and risks. The study included air sampling during two activities: (1) contamination of work clothing by airborne chrysotile (i.e., loading the clothing), and (2) handling and shaking out of the clothes. The clothes were contaminated at three different target airborne chrysotile concentrations (0-0.1 fibers per cubic centimeter [f/cc], 1-2 f/cc, and 2-4 f/cc; two events each for 31-43 minutes; six events total). Arithmetic mean concentrations for the three target loading levels were 0.01 f/cc, 1.65 f/cc, and 2.84 f/cc (National Institute of Occupational Health and Safety [NIOSH] 7402). Following the loading events, six matched 30-minute clothes-handling and shake-out events were conducted, each including 15 minutes of active handling (15-minute means; 0.014-0.097 f/cc) and 15 additional minutes of no handling (30-minute means; 0.006-0.063 f/cc). Percentages of personal clothes-handling TWAs relative to clothes-loading TWAs were calculated for event pairs to characterize exposure potential during daily versus weekly clothes-handling activity. Airborne concentrations for the clothes handler were 0.2-1.4% (eight-hour TWA or daily ratio) and 0.03-0.27% (40-hour TWA or weekly ratio) of loading TWAs. Cumulative chrysotile doses for clothes handling at airborne concentrations tested were estimated to be consistent with lifetime cumulative chrysotile doses associated with ambient air exposure (range for take-home or ambient doses: 0.00044-0.105 f/cc year). © 2014 Society for Risk Analysis.

Occupational exposure to airborne asbestos from phenolic molding material (Bakelite) during sanding, drilling, and related activities.

PubMed

Mowat, Fionna; Bono, Michael; Lee, R J; Tamburello, Susan; Paustenbach, Dennis

2005-10-01

In this study, a historical phenolic (Bakelite) molding material, BMMA-5353, was tested to determine the airborne concentrations of asbestos fibers released during four different activities (sawing, sanding, drilling, and cleanup of dust generated from these activities). Each activity was performed for 30 min, often in triplicate. The primary objective for testing BMMA-5353 was to quantitatively determine the airborne concentration of asbestos fibers, if any, in the breathing zone of workers. Uses of this product typically did not include sawing or sanding, but it may have been drilled occasionally. For this reason, only small quantities were sawed, sanded, and drilled in this simulation study. Personal (n = 40), area (n = 80), and background/clearance (n = 88) air samples were collected during each activity and analyzed for total fiber concentrations using phase contrast microscopy (PCM) and, for asbestos fiber counts, transmission electron microscopy (TEM). The raw PCM-total fiber concentrations were adjusted based on TEM analyses that reported the fraction of asbestos fibers, to derive a PCM-asbestos concentration that would enable calculation of an 8-hour time-weighted average (TWA). The estimated 8-hour TWAs ranged from 0.006 to 0.08 fibers per cubic centimeter using a variety of worker exposure scenarios. Therefore, assuming an exposure scenario in which a worker uses power tools to cut and sand products molded from BMMA-5353 and similar products in the manner evaluated in this study, airborne asbestos concentrations should not exceed current or historical occupational exposure limits.

Polar organic chemical integrative samplers for pesticides monitoring: impacts of field exposure conditions.

PubMed

Lissalde, Sophie; Mazzella, Nicolas; Mazellier, Patrick

2014-08-01

This study focuses on how Polar Organic Chemical Integrative Samplers (POCIS) work in real environmental conditions. A selection of 23 polar pesticides and 8 metabolites were investigated by exposure of triplicates of integrative samplers in two rivers in France for successive 14-day periods. The pesticides and metabolites were trapped not only in Oasis HLB sorbent but also in the polyethersulfone (PES) membrane of the POCIS. The distribution of pesticides depended on the molecular structure. The use of the Performance Reference Compound (PRC) is also discussed here. The impact of some environmental parameters and exposure setup on the transfer of pesticides in POCIS sorbent was studied: river flow rate, biofouling on membranes, sampler holding design and position in the stream. Results show a significant impact of river flow velocity on PRC desorption, especially for values higher than 4 cm·s(-1). Some fouling was observed on the PES membrane which could potentially have an impact on molecule accumulation in the POCIS. Finally, the positioning of the sampler in the river did not have significant effects on pesticide accumulation, when perpendicular exposures were used (sampler positioning in front of the water flow). The POCIS with PRC correction seems to be a suitable tool for estimating time-weighted average (TWA) concentrations, for all the molecules except for one of the nine pesticides analyzed in these two French rivers. Copyright © 2014 Elsevier B.V. All rights reserved.

Exposures to asbestos arising from bandsawing gasket material.

PubMed

Fowler, D P

2000-05-01

A simulation of bandsawing sheet asbestos gasket material was performed as part of a retrospective exposure evaluation undertaken to assist in determining causation of a case of mesothelioma. The work was performed by bandsawing a chrysotile asbestos (80%)/neoprene gasket sheet with a conventional 16-inch woodworking bandsaw inside a chamber. Measurements of airborne asbestos were made using conventional area and personal sampling methods, with analysis of collected samples by transmission electron microscopy (TEM) and phase contrast microscopy (PCM). These were supplemented by qualitative scanning electron microscopy (SEM) examinations of some of the airborne particles collected on the filters. In contrast with findings from studies examining manual handling (installation and removal) of gaskets, airborne asbestos concentrations from this operation were found to be well above current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) (eight-hour time-weighted average [TWA]) and excursion limit (30-minute) standards. Although some "encapsulation" effect of the neoprene matrix was seen on the particles in the airborne dust, unencapsulated individual fiber bundles were also seen. Suggestions for the implications of the work are given. In summary, the airborne asbestos concentrations arising from this work were quite high, and point to the need for careful observation of common sense precautions when manipulation of asbestos-containing materials (even those believed to have limited emissions potential) may involved machining operations.

Derivation of an occupational exposure limit for inorganic borates using a weight of evidence approach.

PubMed

Maier, A; Vincent, M; Hack, E; Nance, P; Ball, W

2014-04-01

Inorganic borates are encountered in many settings worldwide, spurring international efforts to develop exposure guidance (US EPA, 2004; WHO, 2009; ATSDR, 2010) and occupational exposure limits (OEL) (ACGIH, 2005; MAK, 2011). We derived an updated OEL to reflect new data and current international risk assessment frameworks. We assessed toxicity and epidemiology data on inorganic borates to identify relevant adverse effects. International risk assessment frameworks (IPCS, 2005, 2007) were used to evaluate endpoint candidates: reproductive toxicity, developmental toxicity, and sensory irritation. For each endpoint, a preliminary OEL was derived and adjusted based on consideration of toxicokinetics, toxicodynamics, and other uncertainties. Selection of the endpoint point of departures (PODs) is supported by dose-response modeling. Developmental toxicity was the most sensitive systemic effect. An OEL of 1.6mgB/m(3) was estimated for this effect based on a POD of 63mgB/m(3) with an uncertainty factor (UF) of 40. Sensory irritation was considered to be the most sensitive effect for the portal of entry. An OEL of 1.4mgB/m(3) was estimated for this effect based on the identified POD and an UF of 1. An OEL of 1.4mgB/m(3) as an 8-h time-weighted average (TWA) is recommended. Copyright © 2014 Elsevier Inc. All rights reserved.

A review of historical exposures to asbestos among skilled craftsmen (1940-2006).

PubMed

Williams, Pamela R D; Phelka, Amanda D; Paustenbach, Dennis J

2007-01-01

This article provides a review and synthesis of the published and selected unpublished literature on historical asbestos exposures among skilled craftsmen in various nonshipyard and shipyard settings. The specific crafts evaluated were insulators, pipefitters, boilermakers, masons, welders, sheet-metal workers, millwrights, electricians, carpenters, painters, laborers, maintenance workers, and abatement workers. Over 50 documents were identified and summarized. Sufficient information was available to quantitatively characterize historical asbestos exposures for the most highly exposed workers (insulators), even though data were lacking for some job tasks or time periods. Average airborne fiber concentrations collected for the duration of the task and/or the entire work shift were found to range from about 2 to 10 fibers per cubic centimeter (cm3 or cc) during activities performed by insulators in various nonshipyard settings from the late 1960s and early 1970s. Higher exposure levels were observed for this craft during the 1940s to 1950s, when dust counts were converted from millions of particles per cubic foot (mppcf) to units of fibers per cubic centimeter (fibers/cc) using a 1:6 conversion factor. Similar tasks performed in U.S. shipyards yielded average fiber concentrations about two-fold greater, likely due to inadequate ventilation and confined work environments; however, excessively high exposure levels were reported in some British Naval shipyards due to the spraying of asbestos. Improved industrial hygiene practices initiated in the early to mid-1970s were found to reduce average fiber concentrations for insulator tasks approximately two- to five-fold. For most other crafts, average fiber concentrations were found to typically range from <0.01 to 1 fibers/cc (depending on the task or time period), with higher concentrations observed during the use of powered tools, the mixing or sanding of drywall cement, and the cleanup of asbestos insulation or lagging materials. The available evidence suggests that although many historical measurements exceeded the current OSHA 8-h time-weighted average (TWA) permissible exposure limit (PEL) of 0.1 fibers/cc, average fiber concentrations generally did not exceed historical occupational exposure limits in place at the time, except perhaps during ripout activities or the spraying of asbestos in enclosed spaces or onboard ships. Additionally, reported fiber concentrations may not have represented daily or actual human exposures to asbestos, since few samples were collected beyond specific short-term tasks and workers sometimes wore respiratory protective equipment. The available data were not sufficient to determine whether the airborne fiber concentrations represented serpentine or amphibole asbestos fibers, which would have a pronounced impact on the potential health hazards posed by the asbestos. Despite a number of limitations associated with the available air sampling data, the information should provide guidance for reconstructing asbestos exposures for different crafts in specific occupational settings where asbestos was present during the 1940 to 2006 time period.

Exposure to MTBE, TAME and aromatic hydrocarbons during gasoline pump maintenance, repair and inspection.

PubMed

Vainiotalo, Sinikka; Kuusimäki, Leea; Pekari, Kaija

2006-09-01

The exposure of gasoline pump repairers and inspectors to gasoline was studied at service stations and repair shops in Finland in April-June 2004. The average air temperature ranged from 7 degrees C to 16 degrees C and wind speed from 2.5 to 7 m/s. The gasoline blends contained mixtures of methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME), the total content of oxygenates being 11-12%. The content of benzene was <1%. Breathing zone air was collected during the work task using passive monitors. The mean sampling period was 4.5 h. The mean TWA-8 h concentrations for MTBE, TAME, hexane, benzene, toluene, ethylbenzene and xylene were 4.5, 1.3, 0.55, 0.23, 2.2, 0.26 and 1.1 mg/m3, respectively. None of the individual benzene concentrations exceeded the binding limit value for benzene (3.25 mg/m3). The sum concentration of MTBE and TAME in urine was between 8.9 and 530 nmol/l in individual post-shift samples. The individual sum concentrations of the metabolites tert-butyl alcohol and tert-amyl alcohol collected the following morning after the exposure ranged from 81 to 916 nmol/l. All individual results were below corresponding biological action levels. Exposure to aromatic hydrocarbons was estimated from post-shift urine samples, with benzene showing the highest concentration (range 4.4 and 35 nmol/l in non-smokers). The exposure levels were similar to those measured in previous studies during unloading of tanker lorries and railway wagons. The results indicated a slightly higher exposure for inspectors, who calibrated fuel pump gauges at the service stations, than for pump repairers. No significant skin exposure occurred during the study.

Coronal Properties of X-ray bright stars in young associations: abundances, temperatures and variability

NASA Astrophysics Data System (ADS)

Argiroffi, Costanza

2006-03-01

In this work I have investigated open issues related to the X-ray radiation from young stars, including heating mechanisms of the emitting plasma, its chemical composition, and possible effects due to circumstellar accretion disks. To this aim, I have analyzed observations of young nearby stars taken with the X-ray observatories XMM-Newton and Chandra. For a detailed study of the characteristics of the X-ray emitting plasma, I have selected two X-ray bright young stars, TWA 5 and PZ Tel, for which high-resolution X-ray spectroscopy was achievable, and two regions of the young stellar association Upper Scorpius (USco), for which X-ray images and medium-resolution spectra of individual sources were obtained. TWA 5 is a 10 Myr old star in the TW Hydrae association, which is still accreting material from its circumstellar envelope, while PZ Tel is a ? 12 Myr star in the beta Pictoris moving group, which already dissipated its circumstellar disk. The different evolutionary stages of these two stars allow to probe whether X-ray emission is produced, or affected, by accretion processes. High-resolution X-ray spectra of TWA 5 and PZ Tel were gathered with the grating spectrometers on board XMM-Newton and Chandra, respectively. From the measurements of individual emission line fluxes in their X-ray spectra, I have derived emission measure distributions vs. temperature, abundances, and electron densities of the X-ray emitting plasma. I have found that, in spite of their different evolutionary status, hot (T ? 10 MK) plasma is the main responsible for the observed X-ray emission of both stars. The hot plasma on TWA 5 displays peculiar element abundances with respect to the solar photospheric composition with Ne/Fe ? 10(Ne/Fe), while the coronal plasma on PZ Tel shows Ne/Fe ? 3(Ne/Fe). To explain the strong Fe underabundance (? 0.1 Fe) and the extremely high Ne/Fe ratio of TWA 5 I have considered three different scenarios: (1) coronal plasma may be affected by selective element depletion dependent on the first ionization potential (FIP), similar to the inverse FIP effect usually observed in the coronae of very active stars; (2) the X-ray emitting plasma on TWA 5 may be partially heated by the shock produced by the infall accretion streams onto the stellar photosphere, and hence it may originate from the circumstellar disk, where grain depletion is a possible cause of the metal deficiency; (3) the peculiar abundances on TWA 5 are due to the local chemical composition of the original cloud from which the star formed, and this explains why TWA 5 shares the same abundances with TW Hydrae, another young star located in the same stellar association. The 5 Myr old USco association, due to its vicinity (145 pc) and low circumstellar extinction, is a good laboratory to perform a detailed study of PMS stars of this age. Here I present the results of the analysis of deep XMM-Newton observations of two USco regions covering an area of ?0.4 deg^2 . I have detected 224 X-ray sources among which 22 have been identified with probable USco members on the basis of near infrared and optical photometry. Among these 22 sources, I have recognized 13 sources as USco members for the first time. Except for the intermediate mass star HD 142578, all the detected USco sources are low mass stars of spectral type ranging from G to late M, and including at least one brown dwarf. The X-ray spectral analysis of the most intense USco sources indicates metal depleted plasma with temperature of ? 10 MK, resembling the typical case of active main sequence stars, as already found for TWA 5 and PZ Tel. Strong flares detected from 4 USco members have allowed me to derive coronal lengths of the flaring structures by performing time resolved spectroscopy during the flare decay phases. In all cases the flaring loops have sizes of 10^10 - 10^11 cm, hence smaller than the corresponding stellar radii. These results suggest that, in these very young stars coronal plasma is confined in compact loops. The coronal properties of PZ Tel, TWA 5, and of the USco members indicate that the coronae of pre-main sequence stars become similar to those of older active main-sequence stars on short time scales (? 5 Myr), in terms of average temperature, density, elemental abundances, and loop lengths, even if accretion processes from circumstellar disks are still at work.

T-Wave Alternans Is Linked to Microvascular Obstruction and to Recurrent Coronary Ischemia After Myocardial Infarction.

PubMed

Floré, V; Claus, P; Vos, M A; Vandenberk, B; Van Soest, S; Sipido, K R; Adriaenssens, T; Bogaert, J; Desmet, W; Willems, R

2015-11-01

The purpose of this study is to investigate the relationship between T-wave alternans (TWA), infarct size and microvascular obstruction (MVO) and recurrent cardiac morbidity after ST elevation myocardial infarction (STEMI). One hundred six patients underwent TWA testing 1-12 months and 57 patients underwent cardiac magnetic resonance imaging (MRI) in the first 2-4 days after STEMI. During follow-up (3.5 ± 0.5 years), death (n = 2), ventricular tachycardia (n = 3), supraventricular tachycardia (n = 4), heart failure (n = 3) and recurrent coronary ischemia (n = 25) were observed. After multivariate analysis, positive TWA (HR2.59, CI1.10-6.11, p0.024) and larger MVO (HR1.08, CI1.01-1.16, p0.034) were associated with recurrent angina or ACS. Presence of MVO was correlated with TWA (Spearman rho 0.404, p0.002) and the impairment of LVEF (-0.524, p < 0.001). Patients after STEMI remain at a high risk of symptoms of coronary ischemia. The presence of MVO and TWA 1-12 months after STEMI is related to each other and to recurrent angina or ACS.

Validation of Passive Sampling Devices for Monitoring of Munitions Constituents in Underwater Environments

DTIC Science & Technology

2017-09-01

this project, we launched at Esperanza pier (Figure 5-4), which required a minimum of 2 hours of travel time , including transit from Camp Garcia to the...concentrations of emerging contaminants by providing a time -integrated sample with low detection limits and in situ extraction. PSDs are fairly well...A continuous sampling approach allows detection and quantification of chemicals in an integrated manner, providing time - weighted average (TWA

Youngest Brown Dwarf Yet in a Multiple Stellar System

NASA Astrophysics Data System (ADS)

2000-07-01

... and the Sharpest Optical Image (0.18 arcsec) from the VLT so far...! Astronomers are eager to better understand the formation of stars and planets - with an eye on the complex processes that lead to the emergence of our own solar system some 4600 million years ago. Brown Dwarfs (BDs) play a special role in this context. Within the cosmic zoo, they represent a class of "intermediate" objects. While they are smaller than normal stars, they shine by their own energy for a limited time, in contrast to planets. Recent observations with the ESO Very Large Telescope (VLT) of a "young" Brown Dwarf in a multiple stellar system are taking on a particular importance in this connection. An evaluation of the new data by an international team of astronomers [1] shows that it is by far the youngest of only four such objects found in a stellar system so far. The results are now providing new insights into the stellar formation process. This small object is known as TWA-5 B and with a mass of only 15 - 40 times that of Jupiter, it is near the borderline between planets and Brown Dwarfs, cf. the explanatory Appendix to this Press Release. However, visible and infrared VLT spectra unambiguously classify it in the latter category. Accurate positional measurements with the Hubble Space Telescope (HST) and the VLT hint that it is orbiting the central, much heavier and brighter star in this system, TWA-5 A (itself a close double star of which each component presumably has a mass of 0.75 solar masses), with a period that may be as long as 900 years. And, by the way, an (I-band) image of the TWA-5 system is the sharpest delivered by the VLT so far, with an image size of only 0.18 arcsec [2]! Brown Dwarfs: a cool subject In current astronomical terminology, Brown Dwarfs (BDs) are objects whose masses are below those of normal stars - the borderline is believed to be about 8% of the mass of our Sun - but larger than those of planets, cf. [3]. Unlike normal stars, Brown Dwarfs are unable to sustain stable nuclear fusion of hydrogen. Once they have been formed, they enter into a very long phase of slow contraction. This process releases (potential) energy that is emitted in the form of electromagnetic radiation. Their brightness decreases with time, as they become smaller and smaller and their energy reservoir dwindles. A few dozen "free-floating", isolated Brown Dwarfs have been discovered so far in space. They include members of the well-known, comparatively young Pleiades cluster (120 million years old) and some much older ones (some thousands of million years) only a few light-years away. A typical example is Kelu-1 that was found at ESO in 1997, see PR 07/97. However, despite extensive searches and much invested effort, astronomers have so far only found three Brown Dwarfs that have been confirmed as companions to normal stars: Gl 229 B , G196-3 B , and Gl 570 D . The younger a Brown Dwarf is, the more luminous it is, and the nearer it is to us, the brighter it appears in the sky. Old Brown Dwarfs are intrinsically so faint that, with the currently available instruments, they can only be found if they are nearby. It is therefore no surprise that the known, nearby Brown Dwarfs are generally older than the more distant ones, e.g. those found in the Pleiades. A programme to find young Brown Dwarfs It is on this background, that the international astronomer team [1] is now searching for young Brown Dwarfs that are companions to young, nearby stars. However, young stars are quite rare in the solar neighbourhood. Only a few were known before the very successful ROSAT X-ray survey that discovered about 100 young and nearby stars, less than 100 million years old and within ~ 300 light-years distance. The new research programme attempts to find brown dwarf companions to these and other young and nearby stars. For this, state-of-the-art infrared imaging cameras are used at the 3.6-m New Technology Telescope (NTT) with the SOFI (and SHARP) instrument on La Silla, as well as the 8.2-m VLT/ANTU telescope with the ISAAC multi-mode instrument at Paranal. The first step is to take high-resolution images of the stars from the ROSAT list to look for possible faint companions. However, any faint object found near one of the programme stars may of course be a completely unrelated fore- or background object and it is therefore imperative to check this by means of supplementary observations. Two methods are available. The first implies taking spectra of the companion candidates that demonstrate whether they are bona-fide Brown Dwarfs that display spectral lines typical for the cool atmospheres of this class, e.g., of Titanium Oxide (TiO) and Vanadium Oxide (VO). Infrared spectra are particularly useful for a measurement of the atmospheric temperature. The other involves obtaining a second image some years later. If the companion candidate and the brighter star belong to the same stellar system, they must move together on the sky or, as astronomers say, their measured "proper motions" must be (nearly) the same. If both checks are positive, the fainter object is most likely to be a bona-fide Brown Dwarf companion to the young and nearby star. To be absolutely certain, its orbital motion should also be detected, but it will be very slow and can only be perceived after several years of continued observations. VLT observations of TWA-5 B Two years ago, a faint companion candidate was found near one of the young and nearby stars included in the present programme and designated TWA-5 (also known as CoD -33 7795 ). It is about 12 million years old and is a member of a group of about a dozen young stars (of the "T Tauri"-type ), seen in the southern constellation Hydra (the Water-Snake) and grouped around the star TW Hya , the first to be found in this area ("TWA" means the "TW Hya Association"). The HIPPARCOS mission of the European Space Agency (ESA) measured a mean distance to some of these stars of ~ 180 light-years (55 parsec). This faint companion ( "TWA-5 B" ) was first detected in 1998 with the Hubble Space Telescope (HST) , but until now, no spectrum had been published, nor had the proper motion been measured. It is indeed a difficult object to observe: it is 100 times fainter than the bright star and is located only two arcsec away in the sky. ESO PR Photo 17a/00 ESO PR Photo 17a/00 [Preview - JPEG: 400 x 463 pix - 128k] [Normal - JPEG: 800 x 925 pix - 272k] Caption : An image of TWA-5 A (lower, bright object) and TWA-5 B (upper), taken with the FORS-2 multi-mode instrument at the 8.2-m VLT/KUEYEN telescope on 21 February 2000. The integration time was 1 second through an I-band filter (wavelength 900 nm) with the high-resolution collimator (0.1 arcsec per pixel). The image quality is 0.18 arcsec FWHM (full-width-half maximum). The lines emerging from the bright image are caused by optical reflection in the telescope. The angular distance is 2 arcsec, cf. the indicated scale. In order to investigate the nature of this object, the team obtained images and spectra with the Very Large Telescope (VLT) at Paranal. An optical image was taken by ESO staff on 21 February 2000 during a technical test period ( [4]) with the FORS-2 (FOcal Reducer/low dispersion Spectrograph) at the 8.2-m VLT/KUEYEN telescope, cf. PR Photo 17a/00 . This is actually the sharpest optical image so far taken with the VLT, with a FWHM (full-width-at-half-maximum) of only 0.18 arcsec [2] and it shows the images of the primary star ("TWA-5 A") and the 100 times fainter companion ("TWA-5 B") very well separated. An infrared image was taken on 16 April 2000 with the ISAAC (Infrared Spectrograph and Array Camera) multi-mode instrument at the 8.2-m VLT/ANTU telescope. This image was obtained by ESO staff in service mode and again, TWA-5 A and B are both clearly seen. More recently, spectra of TWA-5 B were taken with FORS-2 (optical wavelength region) and ISAAC (infrared). These observations were particularly difficult, because of the need to avoid contamination from the strong light of the much brighter object, only 2 arcsec away. The nature of TWA-5 B ESO PR Photo 17b/00 ESO PR Photo 17b/00 [Preview - JPEG: 509 x 400 pix - 124k] [Normal - JPEG: 1017 x 800 pix - 264k] Caption : This optical spectrum (600 - 900 nm wavelength range) of TWA-5 B was obtained with the FORS-2 instrument at the 8.2-m VLT/KUEYEN telescope on 23 February 2000. A 30-min exposure was made through a 0.7 arcsec wide slit, positioned on the object in east-west direction, i.e., perpendicular to the direction to the much brighter TWA-5 A , only 2 arcsec to the south, see PR Photo 17a/00. Thanks to this, the obtained spectrum was very "clean". Also shown is the optical spectrum of a typical M9-type star. The spectra are very similar, with broad molecular absorption bands from TiO and VO. TWA-5 B also shows strong hydrogen emission (H-alpha) and weak sodium (Na) absorption, both indicative of its comparatively young age. ESO PR Photo 17c/00 ESO PR Photo 17c/00 [Preview - JPEG: 515 x 400 pix - 124k] [Normal - JPEG: 1030 x 800 pix - 284k] Caption : This infrared spectrum was obtained on 16 April 2000 with the ISAAC multi-mode instrument at the 8.2-m VLT/ANTU telescope in the 1.4 - 1.8 µm wavelength range (the H-band), with spectral resolution 500. It corresponds to a total exposure time of 20 min and was made through a 0.6 arcsec wide slit. Lines of Magnesium (Mg), Carbon Monoxide (CO), and the Hydroxyl radical (OH) are identified. The general shape of the spectrum is typical of that of a late M-type dwarf star. For comparison, the infrared spectrum of an M9-type star is shown. The spectra are indeed quite similar. The optical spectrum of TWA-5 B shows strong molecular absorption features (TiO and VO, cf. PR Photo 17b/00 ), typical for very cold stellar atmospheres and confirming it as a Brown Dwarf. Both the optical and the infrared ( PR Photo 17c/00 ) spectra indicate a late spectral type (about M9) of TWA-5 B that corresponds to an atmospheric temperature of "only" ~2200 °C (2500 K). For comparison, that of the Sun is ~ 6000 °C. The hydrogen (H-alpha) emission line indicates strong activity in the upper atmospheric layers (the chromosphere), as normally found in young stars and young Brown Dwarfs. Moreover, the comparatively weak sodium (Na) absorption line shows that this object must be relatively large for its low mass, and that it is still in the early stage of contraction. These are clear signs of young age and fully consistent with TWA-5 B being a bona-fide companion to the young star TWA-5 A . In fact, the possibility that an object as cold as TWA-5 B is located within 2 arcsec from TWA-5 A by chance is less than 10 -8. The motion of TWA-5 B ESO PR Photo 17d/00 ESO PR Photo 17d/00 [Preview - JPEG: 400 x 463 pix - 64k] [Normal - JPEG: 800 x 925 pix - 140k] Caption : The diagramme shows the relative positions of TWA-5 A and TWA-5 B , as measured on the sky by the HST in 1998 (points 1 and 2) and the VLT in 2000 (3 and 4). The ellipses indicate the measurement uncertainties. It is obvious that the two objects move in nearly the same direction and with the same speed. This greatly strengthens the conclusion that they are physically connected in the same multiple stellar system. When comparing the HST positional observations from 1998 and those with the VLT in 2000 ( PR Photo 17d/00 ), it is obvious that TWA-5 A and TWA-5 B move with very nearly the same speed and in the same direction on the sky. There is therefore no doubt that the two objects are physically connected within a stellar multiple system. At the distance of about 180 light-years, the angular separation (2 arcsec) corresponds to a projected distance of 110 AU (about 2.75 times the mean distance between the Sun and the outermost planet in the solar system, Pluto). From this and the mass of TWA-5 A , it is possible to conclude that one full orbit of TWA-5 B around TWA-5 A will last about 900 years. Mass, temperature and age of TWA-5 From the measured optical and infrared brightness of TWA-5 B and the known distance, it is found to be about 400 times fainter than our Sun. Together with the measured temperature, about 2200 °C, and based on theoretical models of Brown Dwarfs, a mass of about 15 to 40 Jupiter masses is deduced. It is also possible to estimate its age; it is found to be very similar as that of TWA-5 A (12 million years), further supporting the conclusion that they were formed at the same time and belong to the same stellar system. TWA-5 B is only the fourth Brown Dwarf so far confirmed as a companion to a normal star , both by spectroscopic and proper motion measurements. It is unique among these by being by far the youngest (12 million years). The others are much older; one is nearly 300 million years old and the other two are several thousand million years old. Indeed, TWA-5 A and its Brown Dwarf companion TWA-5 B are still in the process of formation . The system is the only one so far discovered at this early evolutionary stage. These new findings thus have a direct bearing on the question how Brown Dwarfs form as companions to normal stars. The next steps More detailed investigations of this unique object are now planned. They will include an attempt to detect absorption lines of other elements that are typical for brown dwarfs (especially of lithium) by means of higher-resolution spectra, as well as further imaging that may lead to a detection of the orbital motion within a few years. The team is also actively searching for other very low-mass companions in order to cast more light on some of the fundamental questions, e.g.: What is the mass range of Brown Dwarfs ? What are their orbital characteristics ? Can stars of all masses have Brown Dwarf companions ? Are the distributions of the masses of isolated and companion brown dwarfs similar or different ? Not less exciting, the same observational method can also be used to search for companions of even lower mass, in particular planets. Until now, no extra-solar planets have been detected directly, but only indirectly by other methods, cf. ESO PR 13/00. For this, "deep" images of young nearby stars and their immediate surroundings must be obtained. Young planets are also still relatively hot and, hence, relatively bright, but they are many times fainter than TWA-5 B , hence the need for long exposures. However, such observations are extremely difficult, as any planet - even a young and relatively massive and bright one - will be much fainter than the star around which it revolves and is located very close to it in the sky. One observational method that helps overcome this fundamental obstacle is already used by the team. It consists of taking a very large number (hundreds or even thousands) of very short exposures (1 second or less) and then to add them up using computers (the "speckle method") and suppressing the image blur caused by atmospheric turbulence. In this way, even very faint companions may be detected near bright stars. This will work even better with adaptive optics , e.g. with the CONICA-NAOS instrument that will soon be installed at the third VLT Unit Telescope, MELIPAL. When will the first image of an exoplanet be obtained? This kind of research is very exciting, but also demands great care. A recent event illustrates this. Just a few months ago, the present astronomer team detected a companion candidate to another young star on their list ( TWA-7 ). This object was 100,000 times fainter than and only 2.5 arcsec away from TWA-7 . If it were a true companion orbiting TWA-7 , its mass would have been only 3 Jupiter masses (as deduced from the observed brightness) and it would thus very likely have been a true exoplanet. However, an infrared spectrum subsequently taken with the ISAAC instrument at VLT/ANTU showed that it was in fact a background star, located almost 10,000 light-years farther away than TWA-7 ! Despite the negative result, those observations clearly showed that direct detection and subsequent, effective spectroscopic verification of extra-solar planets is now quite feasible with a ground-based facility like the VLT. It is thus not a very daring prediction that the ongoing searches may soon lead to the first direct images of an extra-solar planet. These are indeed exciting times! More information The work described in this Press Release is discussed by the team in a research article that has been accepted for publication in the European journal Astronomy & Astrophysics. Another paper ( "Direct imaging search for planetary companions next to young nearby stars" ) is also available with more details about the current searches, including the spectrum of the background star at TWA-7. The Principal Investigator for this project may be contacted at: Ralph Neuhaeuser Max-Planck-Institut für Extraterrestrische Physik D-85748 Garching Germany Phone +49-89-32993398 email: rne@mpe.mpg.de Notes [1]: The team consists of Ralph Neuhaeuser (Principal Investigator) and Nuria Huelamo (both Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany), Eike Guenther (Landessternwarte Tautenburg, Germany), Monika Petr (Max-Planck-Institut für Radioastronomie, Bonn, Germany), Wolfgang Brandner (Institute for Astronomy, Honolulu, Hawaii, USA) and João Alves (ESO, Garching, Germany). [2]: The hitherto sharpest image (0.25 arcsec) was obtained in March 1999, cf. ESO PR 06/99. It was obtained during a period of exceptionally good "seeing" (low level of atmospheric turbulence). The installation of adaptive optics at the VLT, foreseen in 2001, will provide a means to overcome the image smearing effect of air turbulence and hence, consistently obtain stellar images of a few hundredths of an arcsecond diameter, near the theoretical limit for an 8.2-m telescope (the telescope diffraction limit ). [3]: 1 solar mass = 2 x 10 30 kg. 1 Jupiter mass = 2 x 10 27 kg ~ 0.001 solar mass. Thus, the "BD-limit" of 0.08 solar masses corresponds to ~ 80 Jupiter masses. [4]: This CCD frame was taken by Paranal Observatory staff during the one of the KUEYEN/FORS-2 "dry runs" in a "technical period", i.e. test observations that served to practise and perfect the operation of the telescope and instrument, before it was made available to the community on April 1, 2000. These and many similar data from this period were quickly released to the community and are available in the publicly accessible area of the VLT Data Archive. Appendix: Planets and Brown Dwarfs Planets and Brown Dwarfs mainly differ by the way they form. While it is believed that Brown Dwarfs (both as companions to normal stars and as isolated objects) form as do normal low-mass stars by fragmentation and subsequent contraction in interstellar gas clouds , planets form in circumstellar gas- and dust disks around their central star. However, an exact dividing line in terms of mass cannot yet be drawn between planets and brown dwarfs, neither from theory nor from observation. It appears that the lower mass limit for Brown Dwarfs is around 0.01 solar masses (about 10 Jupiter masses) and that the upper mass limit for planets is also near this value. Further observations and theoretical progress are needed to clarify this question. Below this mass limit (~ 0.01 solar masses), an object cannot burn the hydrogen isotope deuterium . Planets will therefore have more deuterium in their atmospheres than Brown Dwarfs. One way to distinguish observationally between a planet and a Brown Dwarf is therefore to search for absorption lines of deuterium in the spectrum of the object. These lines would be much stronger in a planet than in a Brown Dwarf. However, such observations would require very high spectral resolution in the infrared region. At this moment, no corresponding observational facilities exist, but it will most probably be possible with the VLT High-Resolution IR Echelle Spectrometer (CRIRES) , currently under development for installation at VLT/ANTU in 2003. The dividing line between real stars on one side and Brown Dwarfs and planets on the other side is better known. Any object that weighs less than ~ 0.08 solar masses cannot sustain stable fusion of hydrogen and also cannot burn the light element lithium.

BANYAN. IX. The Initial Mass Function and Planetary-mass Object Space Density of the TW HYA Association

NASA Astrophysics Data System (ADS)

Gagné, Jonathan; Faherty, Jacqueline K.; Mamajek, Eric E.; Malo, Lison; Doyon, René; Filippazzo, Joseph C.; Weinberger, Alycia J.; Donaldson, Jessica K.; Lépine, Sébastien; Lafrenière, David; Artigau, Étienne; Burgasser, Adam J.; Looper, Dagny; Boucher, Anne; Beletsky, Yuri; Camnasio, Sara; Brunette, Charles; Arboit, Geneviève

2017-02-01

A determination of the initial mass function (IMF) of the current, incomplete census of the 10 Myr-old TW Hya association (TWA) is presented. This census is built from a literature compilation supplemented with new spectra and 17 new radial velocities from ongoing membership surveys, as well as a reanalysis of Hipparcos data that confirmed HR 4334 (A2 Vn) as a member. Although the dominant uncertainty in the IMF remains census incompleteness, a detailed statistical treatment is carried out to make the IMF determination independent of binning while accounting for small number statistics. The currently known high-likelihood members are fitted by a log-normal distribution with a central mass of {0.21}-0.06+0.11 M ⊙ and a characteristic width of {0.8}-0.1+0.2 dex in the 12 M Jup-2 M ⊙ range, whereas a Salpeter power law with α ={2.2}-0.5+1.1 best describes the IMF slope in the 0.1-2 M ⊙ range. This characteristic width is higher than other young associations, which may be due to incompleteness in the current census of low-mass TWA stars. A tentative overpopulation of isolated planetary-mass members similar to 2MASS J11472421-2040204 and 2MASS J11193254-1137466 is identified: this indicates that there might be as many as {10}-5+13 similar members of TWA with hot-start model-dependent masses estimated at ˜5-7 M Jup, most of which would be too faint to be detected in 2MASS. Our new radial velocity measurements corroborate the membership of 2MASS J11472421-2040204, and secure TWA 28 (M8.5 γ), TWA 29 (M9.5 γ), and TWA 33 (M4.5 e) as members. The discovery of 2MASS J09553336-0208403, a young L7-type interloper unrelated to TWA, is also presented.

Microvolt T-wave alternans and beat-to-beat variability of repolarization during early postischemic remodeling in a pig heart.

PubMed

Floré, Vincent; Claus, Piet; Antoons, Gudrun; Oosterhoff, Peter; Holemans, Patricia; Vos, Marc A; Sipido, Karin R; Willems, Rik

2011-07-01

Repolarization variability is considered to predict sudden cardiac death. T-wave alternans (TWA) has been the subject of exhaustive research, whereas beat-to-beat variability of repolarization (BVR) is a new parameter that possibly predicts proarrhythmia. How these parameters interact has not been tested. The purpose of this study was to compare TWA and BVR as predictors of proarrhythmic substrate early after myocardial infarction (MI). In nine pigs, MI was induced by 1-hour occlusion of the left anterior descending coronary artery. Cardiac magnetic resonance imaging was performed at day 21. Six sham pigs served as control. Spectral TWA was tested during right atrial pacing before induction of MI and after 21 days. BVR was calculated from 60 consecutive QT intervals. Magnetic resonance imaging showed transmural MI. TWA was negative in all pigs at clinical threshold rate and equally present in MI versus sham pigs at higher rates (170 bpm: 55% vs 50% positive TWA). In MI pigs, BVR of QT intervals increased significantly during acute ischemia (2.44 ± 0.43 ms vs 3.55 ± 0.41 ms, P <.01) and even more on day 21 (5.80 ± 1.12 ms), but it differed significantly from sham (2.14 ± 0.54 ms, P <.01). A clinical ventricular tachycardia induction protocol was positive in 2 of 8 MI pigs and in none of 6 shams. In early remodeling after MI, BVR at intrinsic heart rate was a consistent phenomenon, whereas TWA during atrial pacing or baseline QT-interval changes were not. TWA and BVR could reflect different post-MI remodeling processes. BVR may be a new technique for predicting a potentially proarrhythmic substrate in the early postinfarction period. Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Close Companions to Nearby Young Stars from Adaptive Optics Imaging on VLT and Keck

NASA Astrophysics Data System (ADS)

Haisch, Karl E.; Jayawardhana, Ray; Brandeker, Alexis; Mardones, Diego

We report the results of VLT and Keck adaptive optics surveys of known members of the η Chamaeleontis, MBM 12, and TW Hydrae (TWA) associations to search for close companions. The multiplicity statistics of η Cha, MBM 12, and TWA are quite high compared with other clusters and associations, although our errors are large due to small number statistics. We have resolved S18 in MBM 12 and RECX 9 in η Cha into triples for the first time. The tight binary TWA 5Aab in the TWA offers the prospect of measuring the dynamical masses of both components as well as an independent distance to the system within a few years. The AO detection of the close companion to the nearby young star χ1 Orionis, previously inferred from radial velocity and astrometric observations, has already made it possible to derive the dynamical masses of that system without any astrophysical assumption.

Chrysotile asbestos exposure associated with removal of automobile exhaust systems (ca. 1945-1975) by mechanics: results of a simulation study.

PubMed

Paustenbach, Dennis J; Madl, Amy K; Donovan, Ellen; Clark, Katherine; Fehling, Kurt; Lee, Terry C

2006-03-01

For decades, asbestos-containing gaskets were used in virtually every system that involved the transport of fluids or gases. Prior to the mid-1970s, some automobile exhaust systems contained asbestos gaskets either at flanges along the exhaust pipes or at the exhaust manifolds of the engine. A limited number of automobile mufflers were lined with asbestos paper. This paper describes a simulation study that characterized personal and bystander exposures to asbestos during the removal of automobile exhaust systems (ca. 1945-1975) containing asbestos gaskets. A total of 16 pre-1974 vehicles with old or original exhaust systems were studied. Of the 16 vehicles, 12 contained asbestos gaskets in the exhaust system and two vehicles had asbestos lining inside the muffler. A total of 82 samples (23 personal, 38 bystander, and 21 indoor background) were analyzed by Phase Contrast Microscopy (PCM) and 88 samples (25 personal, 41 bystander, and 22 indoor background) by Transmission Electron Microscopy (TEM). Only seven of 25 worker samples analyzed by TEM detected asbestos fibers and 18 were below the analytical sensitivity limit (mean 0.013 f/cc, range 0.001-0.074 f/cc). Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results showed an average (1 h) adjusted PCM worker exposure of 0.018 f/cc (0.002-0.04 f/cc). The average (1 h) adjusted PCM airborne concentration for bystanders was 0.008 f/cc (range 0.0008-0.015 f/cc). Assuming a mechanic can replace four automobile single exhaust systems in 1 workday, the estimated 8-h time-weighted average (TWA) for a mechanic performing this work was 0.01 f/cc. Under a scenario where a mechanic might repeatedly conduct exhaust work, these results suggest that exposures to asbestos from work with automobile exhaust systems during the 1950s through the 1970s containing asbestos gaskets were substantially below 0.1 f/cc, the current PEL for chrysotile asbestos, and quite often were not detectable.

Characteristics of Occupational Exposure to Benzene during Turnaround in the Petrochemical Industries

PubMed Central

Shin, Jung-Ah; Lee, Byung-Kyu; Kwon, Jiwoon; Lee, Naroo; Chung, Kwang-Jae; Lee, Jong-Han; Lee, In-Seop; Kang, Seong-Kyu; Jang, Jae-Kil

2010-01-01

Objectives The level of benzene exposure in the petrochemical industry during regular operation has been well established, but not in turnaround (TA), where high exposure may occur. In this study, the characteristics of occupational exposure to benzene during TA in the petrochemical companies were investigated in order to determine the best management strategies and improve the working environment. This was accomplished by evaluating the exposure level for the workers working in environments where benzene was being produced or used as an ingredient during the unit process. Methods From 2003 to 2008, a total of 705 workers in three petrochemical companies in Korea were studied. Long- and short-term (< 1 hr) samples were taken during TAs. TA was classified into three stages: shut-down, maintenance and start-up. All works were classified into 12 occupation categories. Results The long-term geometric mean (GM) benzene exposure level was 0.025 (5.82) ppm (0.005-42.120 ppm) and the short-term exposure concentration during TA was 0.020 (17.42) ppm (0.005-61.855 ppm). The proportions of TA samples exceeding the time-weighted average, occupational exposure level (TWA-OEL in Korea, 1 ppm) and the short-term exposure limit (STEL-OEL, 5 ppm) were 4.1% (20 samples of 488) and 6.0% (13 samples of 217), respectively. The results for the benzene exposure levels and the rates of exceeding the OEL were both statistically significant (p < 0.05). Among the 12 job categories of petrochemical workers, mechanical engineers, plumbers, welders, fieldman and scaffolding workers exhibited long-term samples that exceeded the OEL of benzene, and the rate of exceeding the OEL was statistically significant for the first two occupations (p < 0.05). Conclusion These findings suggest that the periodic work environment must be assessed during non-routine works such as TA. PMID:22953163

Association between lifetime exposure to inorganic arsenic in drinking water and coronary heart disease in Colorado residents.

PubMed

James, Katherine A; Byers, Tim; Hokanson, John E; Meliker, Jaymie R; Zerbe, Gary O; Marshall, Julie A

2015-02-01

Chronic diseases, including coronary heart disease (CHD), have been associated with ingestion of drinking water with high levels of inorganic arsenic (> 1,000 μg/L). However, associations have been inconclusive in populations with lower levels (< 100 μg/L) of inorganic arsenic exposure. We conducted a case-cohort study based on individual estimates of lifetime arsenic exposure to examine the relationship between chronic low-level arsenic exposure and risk of CHD. This study included 555 participants with 96 CHD events diagnosed between 1984 and 1998 for which individual lifetime arsenic exposure estimates were determined using data from structured interviews and secondary data sources to determine lifetime residence, which was linked to a geospatial model of arsenic concentrations in drinking water. These lifetime arsenic exposure estimates were correlated with historically collected urinary arsenic concentrations. A Cox proportional-hazards model with time-dependent CHD risk factors was used to assess the association between time-weighted average (TWA) lifetime exposure to low-level inorganic arsenic in drinking water and incident CHD. We estimated a positive association between low-level inorganic arsenic exposure and CHD risk [hazard ratio (HR): = 1.38, 95% CI: 1.09, 1.78] per 15 μg/L while adjusting for age, sex, first-degree family history of CHD, and serum low-density lipoprotein levels. The risk of CHD increased monotonically with increasing TWAs for inorganic arsenic exposure in water relative to < 20 μg/L (HR = 1.2, 95% CI: 0.6, 2.2 for 20-30 μg/L; HR = 2.2; 95% CI: 1.2, 4.0 for 30-45 μg/L; and HR = 3, 95% CI: 1.1, 9.1 for 45-88 μg/L). Lifetime exposure to low-level inorganic arsenic in drinking water was associated with increased risk for CHD in this population.

Contribution of solid fuel, gas combustion or tobacco smoke to indoor air pollutant concentrations in Irish and Scottish homes

PubMed Central

Semple, S; Garden, C; Coggins, M; Galea, KS; Whelan, P; Cowie, H; Sánchez-Jimenéz, A; Thorne, PS; Hurley, JF; Ayres, JG

2012-01-01

There are limited data describing pollutant levels inside homes that burn solid fuel within developed country settings with most studies describing test conditions or the effect of interventions. This study recruited homes in Ireland and Scotland where open combustion processes take place. Open combustion was classified as coal, peat or wood fuel burning, use of a gas cooker or stove, or where there is at least one resident smoker. 24-hour data on airborne concentrations of particulate matter less than 2.5 microns in size (PM2.5), carbon monoxide (CO), endotoxin in inhalable dust and carbon dioxide (CO2), together with 2–3 week averaged concentrations of nitrogen dioxide (NO2) were collected in 100 houses during the winter and spring of 2009–2010. The geometric mean of the 24-hour time-weighted-average (TWA) PM2.5 concentration was highest in homes with resident smokers (99μg/m3 – much higher than the WHO 24-hour guidance value of 25 μg/m3. Lower geometric mean 24-hour TWA levels were found in homes that burned coal (7 μg/m3) or wood (6 μg/m3) and in homes with gas cookers (7 μg/m3). In peat-burning homes the average 24-hourPM2.5 level recorded was 11 μg/m3. Airborne endotoxin, CO, CO2 and NO2 concentrations were generally within indoor air quality guidance levels. PMID:22007695

The release of lindane from contaminated building materials.

PubMed

Volchek, Konstantin; Thouin, Geneviève; Kuang, Wenxing; Li, Ken; Tezel, F Handan; Brown, Carl E

2014-10-01

The release of the organochlorine pesticide lindane (γ-hexachlorocyclohexane) from several types of contaminated building materials was studied to assess inhalation hazard and decontamination requirements in response to accidental and/or intentional spills. The materials included glass, polypropylene carpet, latex-painted drywall, ceramic tiles, vinyl floor tiles, and gypsum ceiling tiles. For each surface concentration, an equilibrium concentration was determined in the vapour phase of the surrounding air. Vapor concentrations depended upon initial surface concentration, temperature, and type of building material. A time-weighted average (TWA) concentration in the air was used to quantify the health risk associated with the inhalation of lindane vapors. Transformation products of lindane, namely α-hexachlorocyclohexane and pentachlorocyclohexene, were detected in the vapour phase at both temperatures and for all of the test materials. Their formation was greater on glass and ceramic tiles, compared to other building materials. An empiric Sips isotherm model was employed to approximate experimental results and to estimate the release of lindane and its transformation products. This helped determine the extent of decontamination required to reduce the surface concentrations of lindane to the levels corresponding to vapor concentrations below TWA.

Detection and Prevention of Cardiac Arrhythmias During Space Flight

NASA Technical Reports Server (NTRS)

Pillai, Dilip; Rosenbaum, David S.; Liszka, Kathy J.; York, David W.; Mackin, Michael A.; Lichter, Michael J.

2004-01-01

There have been reports suggesting that long-duration space flight might lead to an increased risk of potentially serious heart rhythm disturbances. If space flight does, in fact, significantly decrease cardiac electrical stability, the effects could be catastrophic, potentially leading to sudden cardiac death. It will be important to determine the mechanisms underlying this phenomenon in order to prepare for long-term manned lunar and interplanetary missions and to develop appropriate countermeasures. Our hypothesis is that prolonged exposure to microgravity will alter T wave alternans measurements, decrease heart rate variance, increase QT dispersion, decrease heart rate recovery and alter QT restitution curve. A recently published study has shown that long duration spaceflights prolong cardiac conduction and repolarization. They concluded that long duration flight is associated with QT interval prolongation and may increase arrhythmia susceptibility. We propose using computer technology as a noninvasive clinical tool to detect and study clinically significant TWA during standard exercise testing using electrode systems specifically adapted for the purpose of obtaining and measuring TWA. A population of approximately 15 healthy men and 5 healthy women subjects, representative of the astronaut cohort will be asked to voluntarily participate in this study. Their blood pressure and ECG/TWA will be measured pre-flight and in-flight. Prior to flight, subjects will be asked to participate in an orientation session. Still photos will be taken of the skin where the conductive gel is used for the multi-segment sensors. Photos will be recorded preflight, immediately postflight, and several times during the proceeding week until it has been determined that any skin reaction has disappeared or that no rash is present and will not appear.

United States Air Force Summer Research Program 1991. Graduate Student Research Program (GSRP) Reports. Volume 6. Armstrong Laboratory, Wilford Hall Medical Center

DTIC Science & Technology

1992-01-09

necrosis and thus maintain viability during acute condi- tions of ischemia and compartmental syndrome . It is not known. how- ever, if HBO will continue...adds considerable incentive for flexible database design. Adding to the complexity of the database are emitter sector coverage, radiating power, and...rather, it supplements the time-weighted average(TWA) limit where there are recognized acute effects from a substance whose toxic effects are

Exposure to fuel-oil ash and welding emissions during the overhaul of an oil-fired boiler.

PubMed

Liu, Youcheng; Woodin, Mark A; Smith, Thomas J; Herrick, Robert F; Williams, Paige L; Hauser, Russ; Christiani, David C

2005-09-01

The health effects of exposure to vanadium in fuel-oil ash are not well described at levels ranging from 10 to 500 microg/m(3). As part of a larger occupational epidemiologic study that assessed these effects during the overhaul of a large oil-fired boiler, this study was designed to quantify boilermakers' exposures to fuel-oil ash particles, metals, and welding gases, and to identify determinants of these exposures. Personal exposure measurements were conducted on 18 boilermakers and 11 utility workers (referents) before and during a 3-week overhaul. Ash particles < 10 microm in diameter (PM(10), mg/m(3)) were sampled over full work shifts using a one-stage personal size selective sampler containing a polytetrafluoroethylene filter. Filters were digested using the Parr bomb method and analyzed for the metals vanadium (V), nickel (Ni), iron (Fe), chromium (Cr), cadmium (Cd), lead (Pb), manganese (Mn), and arsenic (As) by inductively coupled plasma mass spectrometry. Nitrogen dioxide (NO(2)) was measured with an Ogawa passive badge-type sampler and ozone (O(3)) with a personal active pump sampler.Time-weighted average (TWA) exposures were significantly higher (p < 0.05) for boilermakers than for utility workers for PM(10) (geometric mean: 0.47 vs. 0.13 mg/m(3)), V (8.9 vs. 1.4 microg/m(3)), Ni (7.4 vs. 1.8 microg/m(3)) and Fe (56.2 vs. 11.2 microg/m(3)). Exposures were affected by overhaul time periods, tasks, and work locations. No significant increases were found for O(3) or NO(2) for boilermakers or utility workers regardless of overhaul period or task group. Fuel-oil ash was a major contributor to boilermakers' exposure to PM(10) and metals. Vanadium concentrations sometimes exceeded the 2003 American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value.

The Interaction of Work Adjustment and Attachment Theory: Employment Counseling Implications

ERIC Educational Resources Information Center

Renfro-Michel, Edina L.; Burlew, Larry D.; Robert, Tracey

2009-01-01

Career development is a lifelong process beginning with career choice. However, career choice alone does not guarantee career success. Rather than focus on choosing a career, the theory of work adjustment (TWA) focuses on the process of becoming an exemplary employee through each stage of an individual's career. Within TWA, employee relationships…

Effects of the TWA Strategy on Expository Reading Comprehension of Students with Autism

ERIC Educational Resources Information Center

Howorth, Sarah; Lopata, Christopher; Thomeer, Marcus; Rodgers, Jonathan

2016-01-01

High-functioning students with autism spectrum disorder (ASD) have been shown to have significant reading comprehension difficulty. This multiple baseline study examined the effect of the think before reading, think while reading, and think after reading (TWA) strategy on expository text comprehension of four boys with ASD. Following baseline,…

Usefulness of the Poincaré maps in detection of T-wave alternans in precordial leads of standard ECG--a comparison with the spectral method.

PubMed

Ruta, J; Strumiłło, P

2001-01-01

T-wave alternans (TWA) at microvolt level is considered as an important non-invasive risk factor for sudden death. Several methods are used to measure such repolarization variations, but each of them has some limitations. The purpose of our study is to assess the usefulness of Poincaré maps, a method based on nonlinear dynamics theory, in detection of repolarization abnormalities. In 30 postinfarction patients presence of TWA in precordial ECG leads was assessed by the spectral method (SM) and by the Poincaré maps (PM). Quantitative measures of both methods: alternans voltage (AV) and alternans distance (AD) were compared using linear regression. Significant correlation between both measures (r = 0.92, p < 0.01) was found. The value of AD > or = 10 microV was accepted as significant for the presence of T-wave alternans. Poincaré mapping seems to be a useful and simple method for detection of TWA. The alternans distance equal or greater than 10 microV can be considered as a level determinative for the presence of TWA.

Investigation of a new acetogen isolated from an enrichment of the tammar wallaby forestomach.

PubMed

Gagen, Emma J; Wang, Jiakun; Padmanabha, Jagadish; Liu, Jing; de Carvalho, Isabela Pena Carvalho; Liu, Jianxin; Webb, Richard I; Al Jassim, Rafat; Morrison, Mark; Denman, Stuart E; McSweeney, Christopher S

2014-12-11

Forestomach fermentation in Australian marsupials such as wallabies and kangaroos, though analogous to rumen fermentation, results in lower methane emissions. Insights into hydrogenotrophy in these systems could help in devising strategies to reduce ruminal methanogenesis. Reductive acetogenesis may be a significant hydrogen sink in these systems and previous molecular analyses have revealed a novel diversity of putative acetogens in the tammar wallaby forestomach. Methanogen-inhibited enrichment cultures prepared from tammar wallaby forestomach contents consumed hydrogen and produced primarily acetate. Functional gene (formyltetrahydrofolate synthetase and acetyl-CoA synthase) analyses revealed a restricted diversity of Clostridiales species as the putative acetogens in the cultures. A new acetogen (growth on H2/CO2 with acetate as primary end product) designated isolate TWA4, was obtained from the cultures. Isolate TWA4 classified within the Lachnospiraceae and demonstrated >97% rrs identity to previously isolated kangaroo acetogens. Isolate TWA4 was a potent hydrogenotroph and demonstrated excellent mixotrophic growth (concomitant consumption of hydrogen during heterotrophic growth) with glycerol. Mixotrophic growth of isolate TWA4 on glycerol resulted in increased cell densities and acetate production compared to autotrophic growth. Co-cultures with an autotrophic methanogen Methanobrevibacter smithii revealed that isolate TWA4 performed reductive acetogenesis under high hydrogen concentration (>5 mM), but not at low concentrations. Under heterotrophic growth conditions, isolate TWA4 did not significantly stimulate methanogenesis in a co-culture with M. smithii contrary to the expectation for organisms growing fermentatively. The unique properties of tammar wallaby acetogens might be contributing factors to reduced methanogen numbers and methane emissions from tammar wallaby forestomach fermentation, compared to ruminal fermentation. The macropod forestomach may be a useful source of acetogens for future strategies to reduce methane emissions from ruminants, particularly if these strategies also include some level of methane suppression and/or acetogen stimulation, for example by harnessing mixotrophic growth capabilities.

[Effects of 1-bromopropane on neurological and hematological changes of female exposed workers].

PubMed

Li, Wei-Hua; Zhou, Zhi-Jun; Wang, Qiang-Yi; Ichihara, Gaku; Takeuchi, Yasuhiro; Ding, Xun-Cheng

2010-05-01

To investigate the health effects of 1-bromopropane (1-BP) on female exposed workers. Four 1-BP manufacturing plants were investigated. Workers were interviewed with questionnaire and examined with neurobehavioral core test battery, nerve conduction velocity tests of nervus tibialis and nervus suralis, vibration sensation test, hematological and biochemical tests. Ambient 1-BP concentration was measured with detection tube, and time-weighed average levels of individual workers were estimated with passive samplers. 1-BP concentration in the plants ranged from 0 to 402.40 mg/m3 (Geomean 32.19 mg/m3). Time-weighted average exposure levels (TWA-8 h) ranged from 0.35 to 535.19 mg/m3 (Geomean 14.08 mg/m3). Compared with the control group, 1-BP exposed workers showed reduced motor nerve conduction velocity [(44.8 +/- 8.7) m/s] and sensory nerve conduction velocity [(45.5 +/- 4.9) m/s], prolonged distal latency [(7.5 +/- 2.1) ms], reduced toe vibration perception, and altered neurobehavior parameters(POMS vigor, tension, anxiety, confusion) significantly (P < 0.05). As to hematological and biochemical indicators, the exposed workers showed decreased white blood cell count [(5.6 +/- 2.17) x 10(3)/microl], red blood cell count [(3.9 +/- 0.4) x 10(6)/microl], hemoglobin [(121.1 +/- 14.5) g/L] and creatine kinase [(82.0 +/- 27.5) IU/L] (P < 0.05), and increased serum total protein (8.0 +/- 0.5 g/dl), lactate dehydrogenase [(335.2 +/- 356.6) IU/L], thyroid-stimulating hormone [(3.6 +/- 2.3) microIU/ml] and follicle-stimulating hormone levels (18.7 +/- 24.4 mIU/ml) (P < 0.05). 1-BP exposure may affect peripheral nerves and central nervous system, and lead to abnormal hematological and biomedical indicators.

Glutaraldehyde inhalation exposure of rats: effects on lung morphology, Clara-cell protein, and hyaluronic acid levels in BAL.

PubMed

Halatek, T; Opalska, B; Swiercz, R; Palczynski, C; Gorski, P; Rydzynski, K; Bernard, A

2003-01-01

Glutaraldehyde (GA) is a biocide widely used in hospital and laboratory practice. GA is a volatile substance and, under certain circumstances, significant airborne concentrations may be generated at room temperature. Occupational exposure to GA by inhalation is suspected of causing delayed irritating effects. In recent years, GA has emerged as the main cause of occupational asthma among health-care workers. The aim of the present study was to evaluate effects of GA inhalatory exposure (0.025 ppm or 0.1 ppm, for 28 days) in rats exposed corresponding to the occupational shift cycle, at time point 24 h, 48 h, and 7 days postexposure (PE). Numerous vacuoles and dilated spaces in epithelial cells in bronchioles showing a destructive effect of GA on the cellular membrane were observed at 24 h PE in 0.1 ppm exposed rats. Lipid vacuoles observed after 48 h PE in higher GA exposure, in the Clara cells of the bronchial epithelium, and in endothelial cells of the alveolar capillaries are probably attributable to disturbed lipid metabolism. Many foci of collagen fibers were observed already after 7 days postexposure. Monitoring of inflammatory response and repair was made possible by using two biomarkers: Clara-cell protein (CC16) and hyaluronic acid (HA). Our results show that the inflammatory repair response contributed to progenitor Clara cells and HA plays a role in the development of fibrotic changes in the lung of rats. Glutaraldehyde in rats causes fibrotic effects at the actual threshold limit value-time weighted average (TLV-TWA) level for GA as specified by current Polish and other national regulations.

Health-hazard evaluation report HETA 88-030-2109, Neiman Sawmills, Inc. , Hulett, Wyoming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tubbs, R.L.

1991-04-01

In response to a request from management, an evaluation was undertaken of possible hazardous working conditions as a result of excessive noise at the Neiman Sawmill facilities (SIC-2421), Hulett, Wyoming. The company produced several varieties of untreated boards and lumber products from pine logs. During this survey 108 workers were employed. Noise dosimetry readings revealed that 73% of the surveyed job descriptions (16 of 22) had time weighted average (TWA) noise levels in excess of 90 decibles-A (dBA). Only one job had TWA levels less than the NIOSH recommended limits of 85dBA. Engineering noise controls produced differing amounts of noisemore » reduction to the workers. An enclosure around the planer in the planer mill was found to be effective. However, the separation of the edger and trimmer operations to their own buildings was not an effective noise reduction technique. Hearing tests revealed that 72.5% of the employees exhibited some degree of hearing impairment at one or more audiometric test frequencies. The author concludes that a health hazard existed for workers. The author recommends that a comprehensive hearing conservation program should be implemented. Recommendations for engineering controls for the mills are included.« less

Evaluations of Technology-Assisted Small-Group Tutoring for Struggling Readers

ERIC Educational Resources Information Center

Madden, Nancy A.; Slavin, Robert E.

2017-01-01

This article reports on 2 experiments in inner-city Baltimore evaluating a computer-assisted tutoring approach, Tutoring With Alphie (TWA), in which 1 paraprofessional can work with up to 6 children at a time. In Study 1, we randomly assigned 14 schools to receive TWA or to continue with whatever approaches they were currently using. Each…

The Construction, Enactment, and Maintenance of Power-as-Domination through an Acquisition: The Case of TWA and Ozark Airlines.

ERIC Educational Resources Information Center

Pierce, Tamyra; Dougherty, Debbie S.

2002-01-01

Explores how domination was created, enacted, and maintained in the acquisition of Ozark Airlines by TWA. Uses the concepts of resources, hegemony, and resistance from the functionalist, Marxist, and postmodern traditions, respectively, to understand power-as-domination as a complex communication process. Reveals how communication practices were…

From Theory of Work Adjustment to Person-Environment Correspondence Counseling: Vocational Psychology as Positive Psychology

ERIC Educational Resources Information Center

Eggerth, Donald E.

2008-01-01

This article argues that vocational psychology is, and has been, positive psychology. It provides an overview of the theory of work adjustment (TWA), one of the most robust and best validated theories in vocational psychology. It also provides an introduction to person-environment-correspondence (PEC) counseling, an extension of the TWA concepts…

The Persuasive Appeal of Mediated Terrorism: The Case of the TWA Flight 847 Hijacking.

ERIC Educational Resources Information Center

Brown, William J.

1990-01-01

Explores the effects of terrorism by approaching it as a persuasive form of communication rather than a dysfunctional sociological act. Describes the rhetorical functions of terrorism, evaluates the persuasive appeal of a mediated narrative, and applies narrative theory to analyze the 1985 TWA Flight 847 hijacking and its terrorist spokesman. (KEH)

Broadband Amplification of Low-Terahertz Signals Using Axis-Encircling Electrons in a Helically Corrugated Interaction Region

NASA Astrophysics Data System (ADS)

He, W.; Donaldson, C. R.; Zhang, L.; Ronald, K.; Phelps, A. D. R.; Cross, A. W.

2017-11-01

Experimental results are presented of a broadband, high power, gyrotron traveling wave amplifier (gyro-TWA) operating in the (75-110)-GHz frequency band and based on a helically corrugated interaction region. The second harmonic cyclotron mode of a 55-keV, 1.5-A, axis-encircling electron beam is used to resonantly interact with a traveling TE21 -like eigenwave achieving broadband amplification. The gyro-TWA demonstrates a 3-dB gain bandwidth of at least 5.5 GHz in the experimental measurement with 9 GHz predicted for a wideband drive source with a measured unsaturated output power of 3.4 kW and gain of 36-38 dB. The approach may allow a gyro-TWA to operate at 1 THz.

Investigation on the optimal magnetic field of a cusp electron gun for a W-band gyro-TWA

NASA Astrophysics Data System (ADS)

Zhang, Liang; He, Wenlong; Donaldson, Craig R.; Cross, Adrian W.

2018-05-01

High efficiency and broadband operation of a gyrotron traveling wave amplifier (gyro-TWA) require a high-quality electron beam with low-velocity spreads. The beam velocity spreads are mainly due to the differences of the electric and magnetic fields that the electrons withstand the electron gun. This paper investigates the possibility to decouple the design of electron gun geometry and the magnet system while still achieving optimal results, through a case study of designing a cusp electron gun for a W-band gyro-TWA. A global multiple-objective optimization routing was used to optimize the electron gun geometry for different predefined magnetic field profiles individually. Their results were compared and the properties of the required magnetic field profile are summarized.

Comparing two-zone models of dust exposure.

PubMed

Jones, Rachael M; Simmons, Catherine E; Boelter, Fred W

2011-09-01

The selection and application of mathematical models to work tasks is challenging. Previously, we developed and evaluated a semi-empirical two-zone model that predicts time-weighted average (TWA) concentrations (Ctwa) of dust emitted during the sanding of drywall joint compound. Here, we fit the emission rate and random air speed variables of a mechanistic two-zone model to testing event data and apply and evaluate the model using data from two field studies. We found that the fitted random air speed values and emission rate were sensitive to (i) the size of the near-field and (ii) the objective function used for fitting, but this did not substantially impact predicted dust Ctwa. The mechanistic model predictions were lower than the semi-empirical model predictions and measured respirable dust Ctwa at Site A but were within an acceptable range. At Site B, a 10.5 m3 room, the mechanistic model did not capture the observed difference between PBZ and area Ctwa. The model predicted uniform mixing and predicted dust Ctwa up to an order of magnitude greater than was measured. We suggest that applications of the mechanistic model be limited to contexts where the near-field volume is very small relative to the far-field volume.

Protoplanetary Disk Masses from Stars to Brown Dwarfs

NASA Astrophysics Data System (ADS)

Mohanty, Subhanjoy; Greaves, Jane; Mortlock, Daniel; Pascucci, Ilaria; Scholz, Aleks; Thompson, Mark; Apai, Daniel; Lodato, Giuseppe; Looper, Dagny

2013-08-01

We present SCUBA-2 850 μm observations of seven very low mass stars (VLMS) and brown dwarfs (BDs). Three are in Taurus and four in the TW Hydrae Association (TWA), and all are classical T Tauri (cTT) analogs. We detect two of the three Taurus disks (one only marginally), but none of the TWA ones. For standard grains in cTT disks, our 3σ limits correspond to a dust mass of 1.2 M ⊕ in Taurus and a mere 0.2 M ⊕ in the TWA (3-10× deeper than previous work). We combine our data with other submillimeter/millimeter (sub-mm/mm) surveys of Taurus, ρ Oph, and the TWA to investigate the trends in disk mass and grain growth during the cTT phase. Assuming a gas-to-dust mass ratio of 100:1 and fiducial surface density and temperature profiles guided by current data, we find the following. (1) The minimum disk outer radius required to explain the upper envelope of sub-mm/mm fluxes is ~100 AU for intermediate-mass stars, solar types, and VLMS, and ~20 AU for BDs. (2) While the upper envelope of apparent disk masses increases with M * from BDs to VLMS to solar-type stars, no such increase is observed from solar-type to intermediate-mass stars. We propose this is due to enhanced photoevaporation around intermediate stellar masses. (3) Many of the disks around Taurus and ρ Oph intermediate-mass and solar-type stars evince an opacity index of β ~ 0-1, indicating significant grain growth. Of the only four VLMS/BDs in these regions with multi-wavelength measurements, three are consistent with considerable grain growth, though optically thick disks are not ruled out. (4) For the TWA VLMS (TWA 30A and B), combining our 850 μm fluxes with the known accretion rates and ages suggests substantial grain growth by 10 Myr, comparable to that in the previously studied TWA cTTs Hen 3-600A and TW Hya. The degree of grain growth in the TWA BDs (2M1207A and SSPM1102) remains largely unknown. (5) A Bayesian analysis shows that the apparent disk-to-stellar mass ratio has a roughly constant mean of log10[M disk/M *] ≈ -2.4 all the way from intermediate-mass stars to VLMS/BDs, supporting previous qualitative suggestions that the ratio is ~1% throughout the stellar/BD domain. (6) Similar analysis shows that the disk mass in close solar-type Taurus binaries (sep <100 AU) is significantly lower than in singles (by a factor of 10), while that in wide solar-type Taurus binaries (>=100 AU) is closer to that in singles (lower by a factor of three). (7) We discuss the implications of these results for planet formation around VLMS/BDs, and for the observed dependence of accretion rate on stellar mass.

Manganese in plasma: a promising biomarker of exposure to Mn in welders. A pilot study.

PubMed

Hoet, Perrine; Vanmarcke, Els; Geens, Tom; Deumer, Gladys; Haufroid, Vincent; Roels, Harry A

2012-08-13

There is raising concern about the potential neurotoxic effects of manganese (Mn) inhalation exposure in welders. Because most of the airborne particles in welding fume are in the respirable fraction, their bioavailability is likely to be higher than for coarser dust exposure. No well-validated biomarker for Mn exposure is available. To investigate the interest of measuring Mn in plasma (Mn-P) and urine (Mn-U) as biomarkers of exposure in a group of 28 welders whose tasks were only welding-related. Ambient air exposure to Mn (Mn-air) was determined by personal full-shift measurements on Monday and Tuesday. On the same days, blood and urine samples were collected before and after the shift. Mn-air varied from 1.3 to 729 μg/m(3) (GM 27.7). For Mn-U 65% of the values in welders were below the LOQ (0.20 μg/L). Compared to controls, the welders' Mn-P averaged 33% higher (1.5 vs 2.0 μg/L). In welders, the after-shift Mn-P values correlated well with Mn-air above 10 μg/m(3). In spite of similar Mn-air exposure on Monday and Tuesday, the relationships between Mn-air and after-shift Mn-P strikingly differed on Tuesday in that the inflection in the relationship was less obvious and the slope of the regression line (Mn-P after-shift/logMn-air) for a doubling of logMn-air was 2.3 times lower than on Monday. On Monday (the first day of the workweek), a Mn-P value of 2 μg/L could distinguish Mn-air exposure above or below 20 μg/m(3) with a sensitivity of 69% and a specificity of 82%. This preliminary study indicates that Mn-P is a promising biomarker of current exposure to Mn in welders and lends biological plausibility to the intended change for the Mn TLV-TWA of 20 μg/m(3) proposed by ACGIH for respirable Mn particulate. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Relationships Among Non-Invasive Predictors of Sudden Cardiac Death During Mental Stress and Exercise In Coronary Artery Disease Patients With Known Arrhythmic Vulnerability

DTIC Science & Technology

2009-12-16

because of the high noise of the ECG recordings, which is a subliminal level of physical exertion. Also, over 80% of the participants were on beta...in TWA assessment. As was stated in the Methods section, MMA-TWA was assessed only during the first stage of the exercise, which is a subliminal

Utility of heart rate turbulence and T-Wave alternans to assess risk for Re-admission and cardiac death in hospitalized heart failure patients.

PubMed

Yamada, Shinya; Yoshihisa, Akiomi; Sato, Yu; Sato, Takamasa; Kamioka, Masashi; Kaneshiro, Takashi; Oikawa, Masayoshi; Kobayashi, Atsushi; Suzuki, Hitoshi; Ishida, Takafumi; Takeishi, Yasuchika

2018-05-18

Heart failure (HF) patients have a higher risk of recurrent HF and cardiac death, and electrical remodeling is considered to be an important factor for HF progression. The present study aimed to validate the utility of electrocardiogram and Holter monitoring for the risk stratification of HF patients. Our study comprised 215 patients (144 males, mean age 62 years) who had been hospitalized due to acute decompensated HF. Electrocardiogram (QRS duration and QTc interval) and 24-hour Holter monitoring (heart rate variability, heart rate turbulence and T-wave alternans [TWA]) were performed in stable condition before discharge. The clinical characteristics and outcomes were then investigated. During a median follow-up period of 2.7 years, there were 83 (38.6%) cardiac events (re-hospitalization due to worsening HF [n = 51] or cardiac death [n = 32]). The patients with cardiac events had a lower turbulence slope (TS) and higher TWA compared to those without cardiac events (TS, 3.0±5.5 ms/RR vs. 5.3±5.6 ms/RR, P = 0.001; TWA, 66.1±19.6 μV vs. 54.7±15.1 μV, P < 0.001). Univariable analysis showed that TS, TWA, QRS duration, and QTc interval were associated with cardiac events (P = 0.004, P < 0.001, P = 0.037 and P = 0.024, respectively), while the multivariable analysis after the adjustment of multiple confounders showed that TS and TWA were independent predictive factors of cardiac events with a hazard ratio of 0.936 and 1.015 (95% confidence interval [CI]: 0.860-0.974, P = 0.006; and 95% CI: 1.003-1.027, p = 0.016), respectively. The measurement of TS and TWA is useful for assessing risk for re-hospitalization and cardiac death in HF patients. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Orbits and masses in the young triple system TWA 5

NASA Astrophysics Data System (ADS)

Köhler, R.; Ratzka, T.; Petr-Gotzens, M. G.; Correia, S.

2013-10-01

Aims: We aim to improve the orbital elements and determine the individual masses of the components in the triple system TWA 5. Methods: Five new relative astrometric positions in the H band were recorded with the adaptive optics system at the Very Large Telescope (VLT). We combine them with data from the literature and a measurement in the Ks band. We derive an improved fit for the orbit of TWA 5Aa-b around each other. Furthermore, we use the third component, TWA 5B, as an astrometric reference to determine the motion of Aa and Ab around their center of mass and compute their mass ratio. Results: We find an orbital period of 6.03 ± 0.01 years and a semi-major axis of 63.7 ± 0.2 mas (3.2 ± 0.1 AU). With the trigonometric distance of 50.1 ± 1.8 pc, this yields a system mass of 0.9 ± 0.1 M⊙, where the error is dominated by the error of the distance. The dynamical mass agrees with the system mass predicted by a number of theoretical models if we assume that TWA5 is at the young end of the age range of the TW Hydrae association. We find a mass ratio of MAb/MAa = 1.3-0.4+0.6 , where the less luminous component Ab is more massive. This result is likely to be a consequence of the large uncertainties due to the limited orbital coverage of the observations. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 079.C-0103, 081.C-0393, 386.C-0205, 087.C-0209, 088.C-0046, 089.C-0167, and 090.C-0184.

Biological effects of short, high-level exposure to gases: ammonia. Phase report, May 1979-May 1980

DOE Office of Scientific and Technical Information (OSTI.GOV)

Legters, L.J.

1980-05-01

This report presents an analysis and synthesis of the available literature concerned with possible health and performance effects of exposures to ammonia. The US Army's concern is with short, high-level exposures that may exceed present threshold limit values of the American Conference of Governmental Industrial Hygienists (25 ppm or 17 mg/cum as a TWA and a ceiling of 35 ppm or 24 mg/cum for 15 minutes). The organs primarily affected by exposure to ammonia gas are the respiratory tract and the eyes. During brief exposures to concentrations of 500 ppm (348 mg/cum) or less, the biologic responses are immediate, reversible,more » and mainly irritant. Below 50 ppm (35 mg/cum), there are no significant effects except that the odor of ammonia is detectable. Between 50-100 ppm (35-70 mg/cum), most people experience some degree of irritation of the eyes, nose and throat. There is some evidence indicating that personnel may become acclimated to the irritant effects after only 1 or 2 weeks of inhalation.« less

Monitoring contaminants of emerging concern from tertiary wastewater treatment plants using passive sampling modelled with performance reference compounds.

PubMed

Sultana, Tamanna; Murray, Craig; Ehsanul Hoque, M; Metcalfe, Chris D

2016-12-01

The Lake Simcoe watershed in Ontario, Canada is an important recreational area and a recharge zone for groundwater resources. Lake Simcoe is a relatively shallow lotic system that has been impacted by urban development, recreation, industry and agriculture. As part of a watershed management plan, six wastewater treatment plants (WWTPs) located in this catchment basin were selected to measure the inputs of contaminants of emerging concern (CECs) of wastewater origin. These WWTPs were recently upgraded to tertiary treatment for phosphorus removal. Polar organic chemical integrative samplers (POCIS) and semipermeable membrane devices (SPMDs) were used to monitor for hydrophilic and hydrophobic CECs, respectively, in treated and untreated wastewater. The passive samplers were calibrated with performance reference compounds (PRCs) by measuring the loss of deuterated beta blocker drugs spiked into POCIS and the loss of PCB congeners spiked into SPMDs over the course of 14-day deployment periods. From the PRC data, field sampling rates of CECs were determined and applied to estimate time-weighted average (TWA) concentrations and mass loadings in mg/day/1000 members of the population serviced. In treated wastewater, TWA concentrations of an antibiotic, sulfamethoxazole, the prescription drugs, carbamazepine, naproxen and gemfibrozil, and the non-prescription drug, ibuprofen, were estimated to be in the low (<18 ng/L) range. The artificial sweeteners, sucralose and acesulfame, were particularly useful chemical tracers, with estimated TWA concentrations in treated wastewater ranging from 128 to 213 ng/L and 4 to 33 ng/L, respectively. The steroid hormones were detected only rarely in treated wastewater. Triclosan, triclocarban and the synthetic musks, HHCB and AHTN, were removed efficiently (>77 %), possibly because of the tertiary treatment technologies. Therefore, the mass loadings for these personal care products were all <5 mg/day/1000 people. Overall, this study indicates that tertiary treatment technologies designed for phosphorus removal do not entirely remove the target CECs.

Biomechanical and psychosocial exposures are independent risk factors for carpal tunnel syndrome: assessment of confounding using causal diagrams.

PubMed

Harris-Adamson, Carisa; Eisen, Ellen A; Neophytou, Andreas; Kapellusch, Jay; Garg, Arun; Hegmann, Kurt T; Thiese, Matthew S; Dale, Ann Marie; Evanoff, Bradley; Bao, Stephen; Silverstein, Barbara; Gerr, Fred; Burt, Susan; Rempel, David

2016-11-01

Between 2001 and 2010, six research groups conducted coordinated prospective studies of carpal tunnel syndrome (CTS) incidence among US workers from various industries to estimate exposure-response relationships. This analysis examined the presence and magnitude of confounding between biomechanical and workplace psychosocial factors and incidence of dominant-hand CTS. 1605 participants, without CTS at enrolment, were followed for up to 3.5 years (2471 person-years). Demographic information, medical history and workplace psychosocial stress measures were collected at baseline. Individual workplace biomechanical exposures were collected for each task and combined across the workweek using time-weighted averaging (TWA). CTS case criteria were based on symptoms and results of electrophysiological testing. HRs were estimated with Cox proportional hazard models. Confounding was assessed using causal diagrams and an empirical criterion of 10% or greater change in effect estimate magnitude. There were 109 incident CTS cases (IR=4.41/100 person-years; 6.7% cumulative incidence). The relationships between CTS and forceful repetition rate, % time forceful hand exertion and the Threshold Limit Value for Hand Activity Level (TLV-HAL) were slightly confounded by decision latitude with effect estimates being attenuated towards the null (10-14% change) after adjustment. The risk of CTS among participants reporting high job strain was attenuated towards the null by 14% after adjusting for the HAL Scale or the % time forceful hand exertions. Although attenuation of the relationships between CTS and some biomechanical and work psychosocial exposures was observed after adjusting for confounding, the magnitudes were small and confirmed biomechanical and work psychosocial exposures as independent risk factors for incident CTS. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Ku-Band Traveling Wave Slot Array Using Simple Scanning Control

NASA Technical Reports Server (NTRS)

Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix A.

2015-01-01

This poster introduces a feeding concept aimed at simplifying the backend (phase shifters) of traditional phased arrays. As an alternative to traditional phased arrays, we employ a traveling wave array (TWA) using a single feedline whose propagation constant is controlled via a single, small mechanical movement without a need for phase shifters to enable scanning. Specifically, a dielectric plunger is positioned within a parallel plate waveguide (PPW) transmission line (TL) that feeds the TWA. By adjusting the position of the dielectric plunger within the PPW feeding the TWA, beam steering is achieved. A 20-element array is designed at 13 gigaherz shown to give stable realized gain across the angular range of minus 25 degrees less than or equal to theta and less than or equal to 25 degrees. A proof of concept array is fabricated and measured to demonstrate and validate the concept's operation.

Ku-Band Traveling Wave Slot Array Using Simple Scanning Control

NASA Technical Reports Server (NTRS)

Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix A.

2015-01-01

This paper introduces a feeding concept aimed at simplifying the backend (phase shifters) of traditional phased arrays. As an alternative to traditional phased arrays, we employ a traveling wave array (TWA) using a single feedline whose propagation constant is controlled via a single, small mechanical movement without a need for phase shifters to enable scanning. Specifically, a dielectric plunger is positioned within a parallel plate waveguide (PPW) transmission line (TL) that feeds the TWA. By adjusting the position of the dielectric plunger within the PPW feeding the TWA, beam steering is achieved. A 20 element array is designed at 13GHz shown to give stable realized gain across the angular range of -25 deg. less than or equal to theta less than or equal to 25 deg. A proof of concept array is fabricated and measured to demonstrate and validate the concept's operation.

The young, tight, and low-mass binary TWA22AB: a new calibrator for evolutionary models?. Orbit, spectral types, and temperature

NASA Astrophysics Data System (ADS)

Bonnefoy, M.; Chauvin, G.; Dumas, C.; Lagrange, A.-M.; Beust, H.; Desort, M.; Teixeira, R.; Ducourant, C.; Beuzit, J.-L.; Song, I.

2009-11-01

Context: Tight binaries discovered in young, nearby associations are ideal targets for providing dynamical mass measurements to test the physics of evolutionary models at young ages and very low masses. Aims: We report the binarity of TWA22 for the first time. We aim at monitoring the orbit of this young and tight system to determine its total dynamical mass using an accurate distance determination. We also intend to characterize the physical properties (luminosity, effective temperature, and surface gravity) of each component based on near-infrared photometric and spectroscopic observations. Methods: We used the adaptive-optics assisted imager NACO to resolve the components, to monitor the complete orbit and to obtain the relative near-infrared photometry of TWA22 AB. The adaptive-optics assisted integral field spectrometer SINFONI was also used to obtain medium-resolution (Rλ=1500-2000) spectra in JHK bands. Comparison with empirical and synthetic librairies were necessary for deriving the spectral type, the effective temperature, and the surface gravity for each component of the system. Results: Based on an accurate trigonometric distance (17.5 ± 0.2 pc) determination, we infer a total dynamical mass of 220 ± 21 MJup for the system. From the complete set of spectra, we find an effective temperature T_eff=2900+200-200 K for TWA22 A and T_eff=2900+200-100 K for TWA22 B and surface gravities between 4.0 and 5.5 dex. From our photometry and an M6 ± 1 spectral type for both components, we find luminosities of log(L/L⊙) = -2.11 ± 0.13 dex and log(L/L⊙) = -2.30 ± 0.16 dex for TWA22 A and B, respectively. By comparing these parameters with evolutionary models, we question the age and the multiplicity of this system. We also discuss a possible underestimation of the mass predicted by evolutionary models for young stars close to the substellar boundary. Based on service-mode observations (072.C-0644, 073.C-0469, 075.C-0521, 076.C-0554, 078.C-0510, 080.C-0581) collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile.

An Integrated Approach to Assess Exposure and Health-Risk from Polycyclic Aromatic Hydrocarbons (PAHs) in a Fastener Manufacturing Industry

PubMed Central

Hsu, Hsin-I; Lin, Ming-Yeng; Chen, Yu-Cheng; Chen, Wang-Yi; Yoon, Chungsik; Chen, Mei-Ru; Tsai, Perng-Jy

2014-01-01

An integrated approach was developed to assess exposure and health-risk from polycyclic aromatic hydrocarbons (PAHs) contained in oil mists in a fastener manufacturing industry. One previously developed model and one new model were adopted for predicting oil mist exposure concentrations emitted from metal work fluid (MWF) and PAHs contained in MWF by using the fastener production rate (Pr) and cumulative fastener production rate (CPr) as predictors, respectively. By applying the annual Pr and CPr records to the above two models, long-term workplace PAH exposure concentrations were predicted. In addition, true exposure data was also collected from the field. The predicted and measured concentrations respectively served as the prior and likelihood distributions in the Bayesian decision analysis (BDA), and the resultant posterior distributions were used to determine the long-term exposure and health-risks posed on workers. Results show that long term exposures to PAHs would result in a 3.1%, 96.7%, and 73.4% chance of exceeding the PEL-TWA (0.2 mg/m3), action level (0.1 mg/m3), and acceptable health risk (10−3), respectively. In conclusion, preventive measures should be taken immediately to reduce workers’ PAH exposures. PMID:25226413

Real-time measurement of dust in the workplace using video exposure monitoring: Farming to pharmaceuticals

NASA Astrophysics Data System (ADS)

Walsh, P. T.; Forth, A. R.; Clark, R. D. R.; Dowker, K. P.; Thorpe, A.

2009-02-01

Real-time, photometric, portable dust monitors have been employed for video exposure monitoring (VEM) to measure and highlight dust levels generated by work activities, illustrate dust control techniques, and demonstrate good practice. Two workplaces, presenting different challenges for measurement, were used to illustrate the capabilities of VEM: (a) poultry farming activities and (b) powder transfer operations in a pharmaceutical company. For the poultry farm work, the real-time monitors were calibrated with respect to the respirable and inhalable dust concentrations using cyclone and IOM reference samplers respectively. Different rankings of exposure for typical activities were found on the small farm studied here compared to previous exposure measurements at larger poultry farms: these were mainly attributed to the different scales of operation. Large variations in the ratios of respirable, inhalable and real-time monitor TWA concentrations of poultry farm dust for various activities were found. This has implications for the calibration of light-scattering dust monitors with respect to inhalable dust concentration. In the pharmaceutical application, the effectiveness of a curtain barrier for dust control when dispensing powder in a downflow booth was rapidly demonstrated.

An assessment of occupational exposure to polycyclic aromatic hydrocarbons in the UK.

PubMed

Unwin, John; Cocker, John; Scobbie, Emma; Chambers, Helen

2006-06-01

A cross-industry occupational hygiene survey was commissioned by the Health and Safety Executive (HSE) to determine the levels of polycyclic aromatic hydrocarbon (PAH) exposure in UK industry and to determine if one or more target analytes were suitable as markers for assessing total exposure to PAHs. There were no broadly applicable UK exposure standards for assessing total exposure to PAHs. Until 1993 a guidance value for assessing exposure in coke ovens only, where PAH exposure is known to be the highest, was based on gravimetric analysis of cyclohexane-soluble material. Biological monitoring based on urinary 1-hydroxypyrene (1-OHP) is widely reported to be an effective indicator of exposure by both dermal and inhalation routes but there was no UK guidance value. The survey involved an occupational hygiene study of 25 sites using both airborne monitoring of a total of 17 individual PAHs and biological monitoring. The results showed 8 h TWA levels of total PAH in air ranged from 0.4 to 1912.6 microg m(-3) with a GM of 15.8 microg m(-3). The profile of PAHs was dominated by naphthalene, the most volatile 2-ring PAH. Airborne benzo(a)pyrene (BaP) correlated well (r(2) = 0.971) with levels of carcinogenic 4-6 ring PAHs and was an effective marker of exposure for all industries where significant particle bound PAH levels were found and, in particular, for CTPV exposure. The 8 h TWA levels of BaP ranged from <0.01 to 6.21 microg m(-3) with a GM of 0.036 microg m(-3); 90% were <0.75 microg m(-3) and 95% were <2.0 microg m(-3). Two hundred and eighteen urine samples collected from different workers at the end of shift and 213 samples collected pre-shift next day were analysed for 1-OHP. Levels of 1-OHP in end-of-shift samples were generally higher than those in pre-shift-next-day samples and showed a good correlation (r(2) = 0.768) to airborne BaP levels if samples from workers using respiratory protection or with significant dermal exposure were excluded. Urinary 1-OHP in end-of-shift samples ranged from the limit of detection (0.5 micromol mol(-1) creatinine) to 60 micromol mol(-1) creatinine with a mean of 2.49 micromol mol(-1) and a 90th percentile value of 6.7 micromol mol(-1) creatinine. The highest 1-OHP levels were found in samples from workers impregnating timber with creosote where exposure was dominated by naphthalene. If the 11 samples from these workers were excluded from the dataset, the 90% value for end-of-shift urine samples was 4 micromol mol(-1) creatinine (n = 207) and this value has since been adopted by the HSE as a biological monitoring benchmark value.

On the possibility of ground-based direct imaging detection of extra-solar planets: the case of TWA-7

NASA Astrophysics Data System (ADS)

Neuhäuser, R.; Brandner, W.; Eckart, A.; Guenther, E.; Alves, J.; Ott, T.; Huélamo, N.; Fernández, M.

2000-02-01

We show that ground-based direct imaging detection of extra-solar planets is possible with current technology. As an example, we present evidence for a possible planetary companion to the young T Tauri star 1RXSJ104230.3-334014 (=TWA-7), discovered by ROSAT as a member of the nearby TW Hya association. In an HST NICMOS F160W image, an object is detected that is more than 9 mag fainter than TWA-7, located 2.445 +/- 0.035'' south-east at a position angle of 142.24 +/- 1.34deg. One year later using the ESO-NTT with the SHARP speckle camera, we obtained H- and K-band detections of this faint object at a separation of 2.536 +/- 0.077'' and a position angle of 139.3 +/- 2.1deg. Given the known proper motion of TWA-7, the pair may form a proper motion pair. If the faint object orbits TWA-7, then its apparent magnitudes of H=16.42 +/- 0.11 and K=16.34 +/- 0.15 mag yield absolute magnitudes consistent with a ~ 106.5 yr old ~ 3 M_jup mass object according to the non-gray theory by Burrows et al. (1997). At ~ 55 pc, the angular separation of ~ 2.5'' corresponds to ~ 138 AU, clearly within typical disk sizes. However, position angles and separations are slightly more consistent with a background object than with a companion. Based on observations obtained at the European Southern Observatory, La Silla (ESO Proposals 62.I-0418 and 63.N-0178), and on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under the NASA contract NAS 5-26555.

OVERVIEW OF AN INTEGRATIVE SAMPLER FOR ...

EPA Pesticide Factsheets

Anthropogenic pollution is recognized as a global problem contributing to degradation of ecosystem quality, to loss of numerous plant and animal species, and to adverse impacts on human health. There is an increasing realization that a holistic hazard assessment of complex environmental contaminant mixtures requires data on the concentrations of hydrophilic organic contaminants as well. An approach to provide a time-weighted average (TWA) assessment is critical in understanding organism exposure to the complex mixture of pollutants present in the environment. A recently developed device, the polar organic chemical integrative sampler (POCIS), is designed to integratively sample the more polar waterborne organic chemicals. Laboratory trials and field deployments have demonstrated that the POCIS is very effective for sequestering hydrophilic chemicals such as antibiotics, hormones, other pharmaceutically derived chemicals, polar pesticides, surfactants, etc. Environmentally derived sample extracts from the integrative samplers are readily amenable for assays utilizing bio-indicator tests. An overview of the POCIS and selected environmental applications will be presented. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality. Located In the subtasks are the various research projects being performed in support of this Task and

Personal exposures to asbestos fibers during brake maintenance of passenger vehicles.

PubMed

Cely-García, María Fernanda; Sánchez, Mauricio; Breysse, Patrick N; Ramos-Bonilla, Juan P

2012-11-01

Brake linings and brake pads are among the asbestos-containing products that are readily available in Colombia. When sold separated from their support, brake linings require extensive manipulation involving several steps that include drilling, countersinking, riveting, bonding, cutting, beveling, and grinding. Without this manipulation, brake linings cannot be installed in a vehicle. The manipulation process may release asbestos fibers, which may expose brake mechanics to the fibers. Three brake repair shops located in Bogotá (Colombia) were sampled for 3 or 4 consecutive days using US National Institute for Occupational Safety and Health (NIOSH) methods 7400 and 7402. Standard procedures for quality control were followed during the sampling process, and asbestos samples were analyzed by an American Industrial Hygiene Association accredited laboratory. Personal samples were collected to assess full-shift and short-term exposures. Area samples were also collected close to the brake-lining manipulation equipment and within office facilities. Activities were documented during the sampling process. Using Phase Contrast Microscopy Equivalent counts to estimate air asbestos concentrations, all personal samples [i.e. 8-h time-weighted averages (TWAs) and 30-min personal samples] were in compliance with the US Occupational Safety and Health Administration standards. Personal asbestos concentrations based on transmission electron microscopy counts were extremely high, ranging from 0.006 to 3.493 f cm(-3) for 8-h TWA and from 0.015 to 8.835 f cm(-3) for 30-min samples. All asbestos fibers detected were chrysotile. Cleaning facilities and grinding linings resulted in the highest asbestos exposures based on transmission electron microscopy counts. There were also some samples that did not comply with the NIOSH's recommended exposure limits. The results indicate that the brake mechanics sampled are exposed to extremely high asbestos concentrations (i.e. based on transmission electron microscopy counts), suggesting that this occupational group could be at excess risk of asbestos-related diseases.

Morbidity and mortality of vermiculite miners and millers exposed to tremolite-actinolite: Part I. Exposure estimates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amandus, H.E.; Wheeler, R.; Jankovic, J.

1987-01-01

The vermiculite ore and concentrate of a mine and mill near Libby, Montana, was found to be contaminated with fibrous tremolite-actinolite. Of 599 fibers (length greater than 5 microns and width greater than 0.45 micron) counted in eight airborne membrane filter samples, 96% had an aspect ratio greater than 10 and 16% had an aspect ratio greater than 50. Additionally, 73% of the fibers were longer than 10 microns, 36% were longer than 20 microns, and 10% were longer than 40 microns. Estimates of exposure before 1964 in the dry mill were 168 fibers/cc for working areas, 182 fibers/cc formore » sweepers, 88 fibers/cc for skipping, and 13 fibers/cc for the quality control laboratory. In 1964-1971, exposure estimates for these areas were 33, 36, 17, and 3 fibers/cc, respectively. Estimates of exposures in the mine before 1971 ranged from 9-23 fibers/cc for drillers and were less than 2 fibers/cc for nondrilling jobs. All 8-hr TWA job exposure estimates decreased from 1972-1976, and from 1977-1982 were less than 1 fiber/cc.« less

The morbidity and mortality of vermiculite miners and millers exposed to tremolite-actinolite: Part I. Exposure estimates.

PubMed

Amandus, H E; Wheeler, R; Jankovic, J; Tucker, J

1987-01-01

The vermiculite ore and concentrate of a mine and mill near Libby, Montana, was found to be contaminated with fibrous tremolite-actinolite. Of 599 fibers (length greater than 5 microns and width greater than 0.45 micron) counted in eight airborne membrane filter samples, 96% had an aspect ratio greater than 10 and 16% had an aspect ratio greater than 50. Additionally, 73% of the fibers were longer than 10 microns, 36% were longer than 20 microns, and 10% were longer than 40 microns. Estimates of exposure before 1964 in the dry mill were 168 fibers/cc for working areas, 182 fibers/cc for sweepers, 88 fibers/cc for skipping, and 13 fibers/cc for the quality control laboratory. In 1964-1971, exposure estimates for these areas were 33, 36, 17, and 3 fibers/cc, respectively. Estimates of exposures in the mine before 1971 ranged from 9-23 fibers/cc for drillers and were less than 2 fibers/cc for nondrilling jobs. All 8-hr TWA job exposure estimates decreased from 1972-1976, and from 1977-1982 were less than 1 fiber/cc.

[Analysis of correlation between pulmonary function and expression levels of matrix metalloproteinases-9 and tissue inhibitor of metalloproteinase-1 among toluene diisocyanate exposed workers].

PubMed

Miao, P P; Meng, T; Jia, Q; Niu, Y; Ye, M; Ji, Y Q; Ju, R; Chen, X L; Shao, H; Zheng, Y X; Dai, Y F

2016-05-01

To investigate the effect of occupational toluene diisocyanate(TDI) exposure on matrix metalloproteinases-9 (MMP-9) and tissue inhibitor of metalloproteinase-1(TIMP-1), and analysis of the correlation of MMP-9,TIMP-1,MMP-9/TIMP-1 and lung function. In October 2014, based on cluster sampling, we conducted a cross-sectional study in a TDI production factory located in China's western region. 61 exposed workers were recruited from workers engaged in packing, operating and checking. Based on different levels of the external exposure, the packers were classified as high exposed group, while operators and checkers as low exposed group. 58 factory managers, matching age and agent, were selected as controls, having same work intense and not contacting the TDI or other allergens. The questionnaire surveys were used to obtain the agent, age, work age, smoking and drinking, personal and family allergic history, occupational history, and the recent health conditions. The levels of MMP-9 and TIMP-1 in serum of subjects were determind by ELISA. The time weighted average concentrations (8h-TWA) were used to describe the levels of TDI air exposure in working environment. Spearman correlation assay was used to investigate the correlation of MMP-9, TIMP-1, MMP-9/TIMP-1 and lung function, exposure time. 8-hour TWA means of TDI air levels in exposed group, packers, operators and checkers were 0.39, 0.76, 0.25 mg/m(3), respectively . According to the external exposure concentration, the packers were classified as high exposed group, and the operators and checkers were classified as low exposed group. In controls, low exposed group and high exposed group, the levels of MMP-9, respectively, were (807.21±347.70),(586.91±317.50),(388.94±312.01) ng/ml (χ(2)=16.69, P<0.001), respectively, and the P50(P25-P75) of MMP-9/TIMP-1 were 4.67(2.87-6.68), 2.3(1.44-3.48), 1.11(0.59-1.48) (χ(2)=39.42, P<0.001), respectively, and the concentrations of TIMP-1, were (173.44±72.67), (236.12±51.98), (302.81±44.39) ng/ml (F=20.09, P< 0.001), respectively. The levels P50(P25-P75) of FVC, FEV1.0 and FEV1.0/FVC in exposed group were, 92.8% (86.0%-101.8%), 85.5%(76.7%-92.8%), 112.5(108.2-118.5), respectively, which were lower than that in control group (124.3%(107.9%-144.2%), 142.7%(119.1%-155.7%), 129.2(123.5-134))(Z values were 7.70, 8.97, 8.62, and all P<0.001). Spearman rank correlation analysis showed that levels of MMP-9 were positively associated with FEV1.0, and FEV1.0/FVC (r values were 0.27, 0.25, respectively, all P<0.05), and The levels of TIMP-1 were negatively associated with FVC, FEV1.0, and FEV1.0/FVC (r valuse were -0.33, -0.39, -0.39, all P<0.05).The levels of MMP-9 were negatively correlated with exposure time(r=-0.26, P=0.040). The positive correlations of MMP-9/TIMP-1 with FVC, FEV1.0, and FEV1.0/FVC were also found (r valuse were 0.34, 0.44, 0.40, all P<0.05). TDI exposure could induce the downs of MMP-9 and MMP-9/TIMP-1 associated with lung functions. The MMP-9 and MMP-9/TIMP-1,in a way, could reflect the respiratory inflammatory injury caused by TDI exposure.

Permeation-solid adsorbent sampling and GC analysis of formaldehyde.

PubMed

Muntuta-Kinyanta, C; Hardy, J K

1991-12-01

A passive method with membrane permeation sampling for the determination of time-weighted-average (TWA) concentration of formaldehyde in air is described. The sampling device was constructed by affixing an unbacked dimethyl silicone membrane to the base of a glass tube and by sealing the top with a rubber stopper. Formaldehyde permeates the membrane and reacts with 2-(hydroxymethyl)piperidine (2-HMP) coated on the surface of XAD-2. Sampling times from 15 min to 8 hr have been used. The formaldehyde-oxazolidine produced is thermally desorbed and determined by a packed column gas chromatograph equipped with a flame ionization detector (FID). The response of the monitor is directly proportional to the external concentration of formaldehyde over the concentration range 0.050-100 ppm. The permeation constant (the slope of the permeation curve) of the membrane is 0.333 mug ppm(-1). hr, and the detection limit of the method is 0.03 ppm for an 8-hr sampling period. Relative humidity (RH) (35-94%), temperature (0-82 degrees ) and storage period (0-25 days) do not affect the permeation process for sample collection. Moreover, potential chemical interferences, 10 ppm acetone or acrolein, respectively, have no detectable effect on the process. The method gives TWA concentration directly from the measurements, and the equipment is economical and convenient for personal or multi-location sample collections.

Magnetic field characteristics of electric bed-heating devices.

PubMed

Wilson, B W; Lee, G M; Yost, M G; Davis, K C; Heimbigner, T; Buschbom, R L

1996-01-01

Measurements of the flux density and spectra of magnetic fields (MFs) generated by several types of electric bed heaters (EBH) were made in order to characterize the MFs to which the fetus may be exposed in utero from the mother's use of these devices. Data on MPs were gathered from more than 1,300 in-home and laboratory spot measurements. In-home measurements taken at seven different positions 10 cm from the EBHs determined that the mean flux density at the estimated position of the fetus relative to the device was 0.45 microT (4.5 mG) for electric blankets and 0.20 microT (2.0 mG) for electrically heated water beds. A rate-of-change (RC) metric applied to the nighttime segment of 24 h EMDEX-C personal-dosimeter measurements, which were taken next to the bed of volunteers, yielded an approximate fourfold to sixfold higher value for electric blanket users compared to water-bed heater users. These same data records yielded an approximate twofold difference for the same measurements when evaluated by the time-weighted-average (TWA)MF exposure metric. Performance of exposure meters was checked against standard fields generated in the laboratory, and studies of sources of variance in the in-home measurement protocols were carried out. Spectral measurements showed that the EBH's measured produced no appreciable high-frequency MFs. Data gathered during this work will be used in interpreting results from a component of the California Pregnancy Outcome Study, which evaluates the use of EBHs as a possible risk factor in miscarriage.

An in-situ assessment of low-density polyethylene and silicone rubber passive samplers using methods with and without performance reference compounds in the context of investigation of polychlorinated biphenyl sources in rivers.

PubMed

Estoppey, Nicolas; Schopfer, Adrien; Fong, Camille; Delémont, Olivier; De Alencastro, Luiz F; Esseiva, Pierre

2016-12-01

This study firstly aims to assess the field performances of low density polyethylene (LDPE) and silicone rubber (SR) samplers for the monitoring of polychlorinated biphenyls (PCBs) in water regarding the uptake, the sampling rate (R S ) estimated by using performance reference compounds (PRCs) and the time-weighted average (TWA) concentrations. The second aim is to evaluate the efficiency of these samplers to investigate PCB sources (localization and imputation steps) using methods with and without PRCs to correct for the impact of water velocity on the uptake. Samplers spiked with PRCs were deployed in the outfalls of two PCB sources and at 8 river sites situated upstream and downstream of the outfalls. After 6weeks, the uptake of PCBs in the linear phase was equivalent in LDPE and SR but 5 times lower in LDPE for PCBs approaching equilibrium. PRC-based R S and water velocity (0.08 to 1.21ms -1 ) were well correlated in river (LDPE: R 2 =0.91, SR: R 2 =0.96) but not in outfalls (higher turbulences and potential release of PRCs to air). TWA concentrations obtained with SR were slightly higher than those obtained with LDPE (factor 1.4 to 2.6 in river) likely because of uncertainty in sampler-water partition coefficient values. Concentrations obtained through filtration and extraction of water samples (203L) were 1.6 and 5.1 times higher than TWA concentrations obtained with SR and LDPE samplers, respectively. PCB sources could efficiently be localized when PRCs were used (increases of PCB loads in river) but the impact of high differences of water velocity was overcorrected (leading sometimes to false positives and negatives). Increases of PCB loads in the river could not be entirely imputed to the investigated sources (underestimation of PCBs contributing to the load increases). A method without PRCs (relationship between uptake and water velocity) appeared to be a good complementary method for LDPE. Copyright © 2016. Published by Elsevier B.V.

Mass, surface area and number metrics in diesel occupational exposure assessment.

PubMed

Ramachandran, Gurumurthy; Paulsen, Dwane; Watts, Winthrop; Kittelson, David

2005-07-01

While diesel aerosol exposure assessment has traditionally been based on the mass concentration metric, recent studies have suggested that particle number and surface area concentrations may be more health-relevant. In this study, we evaluated the exposures of three occupational groups-bus drivers, parking garage attendants, and bus mechanics-using the mass concentration of elemental carbon (EC) as well as surface area and number concentrations. These occupational groups are exposed to mixtures of diesel and gasoline exhaust on a regular basis in various ratios. The three groups had significantly different exposures to workshift TWA EC with the highest levels observed in the bus garage mechanics and the lowest levels in the parking ramp booth attendants. In terms of surface area, parking ramp attendants had significantly greater exposures than bus garage mechanics, who in turn had significantly greater exposures than bus drivers. In terms of number concentrations, the exposures of garage mechanics exceeded those of ramp booth attendants by a factor of 5-6. Depending on the exposure metric chosen, the three occupational groups had quite different exposure rankings. This illustrates the importance of the choice of exposure metric in epidemiological studies. If these three occupational groups were part of an epidemiological study, depending on the metric used, they may or may not be part of the same similarly exposed group (SEG). The exposure rankings (e.g., low, medium, or high) of the three groups also changes with the metric used. If the incorrect metric is used, significant misclassification errors may occur.

Comparison between active (pumped) and passive (diffusive) sampling methods for formaldehyde in pathology and histology laboratories.

PubMed

Lee, Eun Gyung; Magrm, Rana; Kusti, Mohannad; Kashon, Michael L; Guffey, Steven; Costas, Michelle M; Boykin, Carie J; Harper, Martin

2017-01-01

This study was to determine occupational exposures to formaldehyde and to compare concentrations of formaldehyde obtained by active and passive sampling methods. In one pathology and one histology laboratories, exposure measurements were collected with sets of active air samplers (Supelco LpDNPH tubes) and passive badges (ChemDisk Aldehyde Monitor 571). Sixty-six sample pairs (49 personal and 17 area) were collected and analyzed by NIOSH NMAM 2016 for active samples and OSHA Method 1007 (using the manufacturer's updated uptake rate) for passive samples. All active and passive 8-hr time-weighted average (TWA) measurements showed compliance with the OSHA permissible exposure limit (PEL-0.75 ppm) except for one passive measurement, whereas 78% for the active and 88% for the passive samples exceeded the NIOSH recommended exposure limit (REL-0.016 ppm). Overall, 73% of the passive samples showed higher concentrations than the active samples and a statistical test indicated disagreement between two methods for all data and for data without outliers. The OSHA Method cautions that passive samplers should not be used for sampling situations involving formalin solutions because of low concentration estimates in the presence of reaction products of formaldehyde and methanol (a formalin additive). However, this situation was not observed, perhaps because the formalin solutions used in these laboratories included much less methanol (3%) than those tested in the OSHA Method (up to 15%). The passive samplers in general overestimated concentrations compared to the active method, which is prudent for demonstrating compliance with an occupational exposure limit, but occasional large differences may be a result of collecting aerosolized droplets or splashes on the face of the samplers. In the situations examined in this study the passive sampler generally produces higher results than the active sampler so that a body of results from passive samplers demonstrating compliance with the OSHA PEL would be a valid conclusion. However, individual passive samples can show lower results than a paired active sampler so that a single result should be treated with caution.

Indoor air quality in an automotive assembly plant in Selangor, Malaysia.

PubMed

Edimansyah, B A; Rusli, B N; Naing, L; Azwan, B A; Aziah, B D

2009-01-01

The purpose of this study was to determine the indoor air quality (IAQ) status of an automotive assembly plant in Rawang, Selangor, Malaysia using selected IAQ parameters, such as carbon dioxide (CO2), carbon monoxide (CO), temperature, relative humidity (RH) and respirable particulate matter (PM10). A cross-sectional study was conducted in the paint shop and body shop sections of the plant in March 2005. The Q-TRAK Plus IAQ Monitor was used to record the patterns of CO, CO2, RH and temperature; whilst PM10 was measured using DUSTTRAK Aerosol Monitor over an 8-hour time weight average (8-TWA). It was found that the average temperatures, RH and PM10 in the paint shop section and body shop sections exceeded the Department of Safety and Health (DOSH) standards. The average concentrations of RH and CO were slightly higher in the body shop section than in the paint shop section, while the average concentrations of temperature and CO2 were slightly higher in the paint shop section than in the body shop section. There was no difference in the average concentrations of PM10 between the two sections.

Contribution of solid fuel, gas combustion, or tobacco smoke to indoor air pollutant concentrations in Irish and Scottish homes.

PubMed

Semple, S; Garden, C; Coggins, M; Galea, K S; Whelan, P; Cowie, H; Sánchez-Jiménez, A; Thorne, P S; Hurley, J F; Ayres, J G

2012-06-01

  There are limited data describing pollutant levels inside homes that burn solid fuel within developed country settings with most studies describing test conditions or the effect of interventions. This study recruited homes in Ireland and Scotland where open combustion processes take place. Open combustion was classified as coal, peat, or wood fuel burning, use of a gas cooker or stove, or where there is at least one resident smoker. Twenty-four-hour data on airborne concentrations of particulate matter<2.5 μm in size (PM2.5), carbon monoxide (CO), endotoxin in inhalable dust and carbon dioxide (CO2), together with 2-3 week averaged concentrations of nitrogen dioxide (NO2) were collected in 100 houses during the winter and spring of 2009-2010. The geometric mean of the 24-h time-weighted-average (TWA) PM2.5 concentration was highest in homes with resident smokers (99 μg/m3--much higher than the WHO 24-h guidance value of 25 μg/m3). Lower geometric mean 24-h TWA levels were found in homes that burned coal (7 μg/m3) or wood (6 μg/m3) and in homes with gas cookers (7 μg/m3). In peat-burning homes, the average 24-h PM2.5 level recorded was 11 μg/m3. Airborne endotoxin, CO, CO2, and NO2 concentrations were generally within indoor air quality guidance levels. Little is known about indoor air quality (IAQ) in homes that burn solid or fossil-derived fuels in economically developed countries. Recent legislative changes have moved to improve IAQ at work and in enclosed public places, but there remains a real need to begin the process of quantifying the health burden that arises from indoor air pollution within domestic environments. This study demonstrates that homes in Scotland and Ireland that burn solid fuels or gas for heating and cooking have concentrations of air pollutants generally within guideline levels. Homes where combustion of cigarettes takes place have much poorer air quality. © 2011 John Wiley & Sons A/S.

Children's exposure assessment of radiofrequency fields: Comparison between spot and personal measurements.

PubMed

Gallastegi, Mara; Huss, Anke; Santa-Marina, Loreto; Aurrekoetxea, Juan J; Guxens, Mònica; Birks, Laura Ellen; Ibarluzea, Jesús; Guerra, David; Röösli, Martin; Jiménez-Zabala, Ana

2018-05-24

Radiofrequency (RF) fields are widely used and, while it is still unknown whether children are more vulnerable to this type of exposure, it is essential to explore their level of exposure in order to conduct adequate epidemiological studies. Personal measurements provide individualized information, but they are costly in terms of time and resources, especially in large epidemiological studies. Other approaches, such as estimation of time-weighted averages (TWAs) based on spot measurements could simplify the work. The aims of this study were to assess RF exposure in the Spanish INMA birth cohort by spot measurements and by personal measurements in the settings where children tend to spend most of their time, i.e., homes, schools and parks; to identify the settings and sources that contribute most to that exposure; and to explore if exposure assessment based on spot measurements is a valid proxy for personal exposure. When children were 8 years old, spot measurements were conducted in the principal settings of 104 participants: homes (104), schools and their playgrounds (26) and parks (79). At the same time, personal measurements were taken for a subsample of 50 children during 3 days. Exposure assessment based on personal and on spot measurements were compared both in terms of mean exposures and in exposure-dependent categories by means of Bland-Altman plots, Cohen's kappa and McNemar test. Median exposure levels ranged from 29.73 (in children's bedrooms) to 200.10 μW/m 2 (in school playgrounds) for spot measurements and were higher outdoors than indoors. Median personal exposure was 52.13 μW/m 2 and median levels of assessments based on spot measurements ranged from 25.46 to 123.21 μW/m 2 . Based on spot measurements, the sources that contributed most to the exposure were FM radio, mobile phone downlink and Digital Video Broadcasting-Terrestrial, while indoor and personal sources contributed very little (altogether <20%). Similar distribution was observed with personal measurements. There was a bias proportional to power density between personal measurements and estimates based on spot measurements, with the latter providing higher exposure estimates. Nevertheless, there were no systematic differences between those methodologies when classifying subjects into exposure categories. Personal measurements of total RF exposure showed low to moderate agreement with home and bedroom spot measurements and agreed better, though moderately, with TWA based on spot measurements in the main settings where children spend time (homes, schools and parks; Kappa = 0.46). Exposure assessment based on spot measurements could be a feasible proxy to rank personal RF exposure in children population, providing that all relevant locations are being measured. Copyright © 2018. Published by Elsevier Ltd.

Pharmaceuticals, alkylphenols and pesticides in Mediterranean coastal waters: Results from a pilot survey using passive samplers

NASA Astrophysics Data System (ADS)

Munaron, Dominique; Tapie, Nathalie; Budzinski, Hélène; Andral, Bruno; Gonzalez, Jean-Louis

2012-12-01

21 pharmaceuticals, 6 alkylphenols and 27 hydrophilic pesticides and biocides were investigated using polar organic contaminant integrative samplers (POCIS) during a large-scale study of contamination of French Mediterranean coastal waters. Marine and transitional water-bodies, defined under the EU Water Framework Directive were monitored. Our results show that the French Mediterranean coastal waters were contaminated with a large range of emerging contaminants, detected at low concentrations during the summer season. Caffeine, carbamazepine, theophilline and terbutaline were detected with a detection frequency higher than 83% in the coastal waters sampled, 4-nonylphenol (4-NP), 4-tert-octylphenol (4-OP) and 4-nonylphenol diethoxylate (NP2EO) were detected in all coastal waters sampled, and diuron, terbuthylazine, atrazine, irgarol and simazine were detected in more than 77% of samples. For pharmaceuticals, highest time-weighted average (TWA) concentrations were measured for caffeine and carbamazepine (32 and 12 ng L-1, respectively). For alkylphenols, highest TWA concentrations were measured for 4-nonylphenol mono-ethoxylate and 4-nonylphenol (41 and 33 ng L-1, respectively), and for herbicides and biocides, they were measured for diuron and irgarol (33 and 2.5 ng L-1, respectively). Except for Diana lagoon, lagoons and semi-enclosed bays were the most contaminated areas for herbicides and pharmaceuticals, whilst, for alkylphenols, levels of contamination were similar in lagoons and coastal waters. This study demonstrates the relevance and utility of POCIS as quantitative tool for measuring low concentrations of emerging contaminants in marine waters.

DGT Passive Sampling for Quantitative in Situ Measurements of Compounds from Household and Personal Care Products in Waters.

PubMed

Chen, Wei; Li, Yanying; Chen, Chang-Er; Sweetman, Andrew J; Zhang, Hao; Jones, Kevin C

2017-11-21

Widespread use of organic chemicals in household and personal care products (HPCPs) and their discharge into aquatic systems means reliable, robust techniques to monitor environmental concentrations are needed. The passive sampling approach of diffusive gradients in thin-films (DGT) is developed here and demonstrated to provide in situ quantitative and time-weighted average (TWA) measurement of these chemicals in waters. The novel technique is developed for HPCPs, including preservatives, antioxidants and disinfectants, by evaluating the performance of different binding agents. Ultrasonic extraction of binding gels in acetonitrile gave good and consistent recoveries for all test chemicals. Uptake by DGT with HLB (hydrophilic-lipophilic-balanced) as the binding agent was relatively independent of pH (3.5-9.5), ionic strength (0.001-0.1 M) and dissolved organic matter (0-20 mg L -1 ), making it suitable for applications across a wide range of environments. Deployment time and diffusion layer thickness dependence experiments confirmed DGT accumulated chemicals masses are consistent with theoretical predictions. The technique was further tested and applied in the influent and effluent of a wastewater treatment plant. Results were compared with conventional grab-sampling and 24-h-composited samples from autosamplers. DGT provided TWA concentrations over up to 18 days deployment, with minimal effects from biofouling or the diffusive boundary layer. The field application demonstrated advantages of the DGT technique: it gives in situ analyte preconcentration in a simple matrix, with more quantitative measurement of the HPCP analytes.

Monitoring Volatile Organic Compounds (VOCs) in real-time on oil and natural gas production sites

NASA Astrophysics Data System (ADS)

Lupardus, R.; Franklin, S. B.

2017-12-01

Oil and Natural Gas (O&NG) development, production, infrastructure, and associated processing activities can be a substantial source of air pollution, yet relevant data and real-time quantification methods are lacking. In the current study, O&NG fugitive emissions of Volatile Organic Compounds (VOCs) were quantified in real-time and used to determine the spatial and temporal windows of exposure for proximate flora and fauna. Eleven O&NG sites on the Pawnee National Grassland in Northeastern Colorado were randomly selected and grouped according to production along with 13 control sites from three geographical locations. At each site, samples were collected 25 m from the wellhead in NE, SE, and W directions. In each direction, two samples were collected with a Gasmet DX4040 gas analyzer every hour from 8:00 am to 2:00 pm (6 hours total), July to October, 2016 (N=864). VOC concentrations generally increased during the 6 hr. day with the exception of N2O and were predominately the result of O&NG production and not vehicle exhaust. Thirteen of 24 VOCs had significantly different levels between production groups, frequently above reference standards and at biologically relevant levels for flora and fauna. The most biologically relevant VOCs, found at concentrations exceeding time weighted average permissible exposure limits (TWA PELs), were benzene and acrolein. Generalized Estimating Equations (GEEs) measured the relative quality of statistical models predicting benzene concentrations on sites. The data not only confirms that O&NG emissions are impacting the region, but also that this influence is present at all sites, including controls. Increased real-time VOC monitoring on O&NG sites is required to identify and contain fugitive emissions and to protect human and environmental health.

Evaluation of the risk of noise-induced hearing loss among unscreened male industrial workers.

PubMed

Prince, Mary M; Gilbert, Stephen J; Smith, Randall J; Stayner, Leslie T

2003-02-01

Variability in background risk and distribution of various risk factors for hearing loss may explain some of the diversity in excess risk of noise-induced hearing loss (NIHL). This paper examines the impact of various risk factors on excess risk estimates of NIHL using data from the 1968-1972 NIOSH Occupational Noise and Hearing Survey (ONHS). Previous analyses of a subset of these data focused on 1172 highly "screened" workers. In the current analysis, an additional 894 white males (609 noise-exposed and 285 controls), who were excluded for various reasons (i.e., nonoccupational noise exposure, otologic or medical conditions affecting hearing, prior occupational noise exposure) have been added 2066) to assess excess risk of noise-induced material impairment in an unscreened population. Data are analyzed by age, duration of exposure, and sound level (8-h TWA) for four different definitions of noise-induced hearing impairment, defined as the binaural pure-tone average (PTA) hearing threshold level greater than 25 dB for the following frequencies: (a) 1-4 kHz (PTA1234), (b) 1-3 kHz (PTA123), (c) 0.5, 1, and 2 kHz (PTA512), and (d) 3, 4, and 6 kHz (PTA346). Results indicate that populations with higher background risks of hearing loss may show lower excess risks attributable to noise relative to highly screened populations. Estimates of lifetime excess risk of hearing impairment were found to be significantly different between screened and unscreened population for noise levels greater than 90 dBA. Predicted age-related risk of material hearing impairment in the ONHS unscreened population was similar to that predicted from Annex B and C of ANSI S3.44 for ages less than 60 years. Results underscore the importance of understanding differential risk patterns for hearing loss and the use of appropriate reference (control) populations when evaluating risk of noise-induced hearing impairment among contemporary industrial populations.

A multichannel decision-level fusion method for T wave alternans detection

NASA Astrophysics Data System (ADS)

Ye, Changrong; Zeng, Xiaoping; Li, Guojun; Shi, Chenyuan; Jian, Xin; Zhou, Xichuan

2017-09-01

Sudden cardiac death (SCD) is one of the most prominent causes of death among patients with cardiac diseases. Since ventricular arrhythmia is the main cause of SCD and it can be predicted by T wave alternans (TWA), the detection of TWA in the body-surface electrocardiograph (ECG) plays an important role in the prevention of SCD. But due to the multi-source nature of TWA, the nonlinear propagation through thorax, and the effects of the strong noises, the information from different channels is uncertain and competitive with each other. As a result, the single-channel decision is one-sided while the multichannel decision is difficult to reach a consensus on. In this paper, a novel multichannel decision-level fusion method based on the Dezert-Smarandache Theory is proposed to address this issue. Due to the redistribution mechanism for highly competitive information, higher detection accuracy and robustness are achieved. It also shows promise to low-cost instruments and portable applications by reducing demands for the synchronous sampling. Experiments on the real records from the Physikalisch-Technische Bundesanstalt diagnostic ECG database indicate that the performance of the proposed method improves by 12%-20% compared with the one-dimensional decision method based on the periodic component analysis.

Maternal sensitivity and infant autonomic and endocrine stress responses.

PubMed

Bosquet Enlow, Michelle; King, Lucy; Schreier, Hannah Mc; Howard, Jamie M; Rosenfield, David; Ritz, Thomas; Wright, Rosalind J

2014-07-01

Early environmental exposures may help shape the development of the autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) axis, influencing vulnerability for health problems across the lifespan. Little is known about the role of maternal sensitivity in influencing the development of the ANS in early life. To examine associations among maternal sensitivity and infant behavioral distress and ANS and HPA axis reactivity to the Repeated Still-Face Paradigm (SFP-R), a dyadic stress task. Observational repeated measures study. Thirty-five urban, sociodemographically diverse mothers and their 6-month-old infants. Changes in infant affective distress, heart rate, respiratory sinus arrhythmia (RSA), and T-wave amplitude (TWA) across episodes of the SFP-R were assessed. A measure of cortisol output (area under the curve) in the hour following cessation of the SFP-R was also obtained. Greater maternal insensitivity was associated with greater infant sympathetic activation (TWA) during periods of stress and tended to be associated with greater cortisol output following the SFP-R. There was also evidence for greater affective distress and less parasympathetic activation (RSA) during the SFP-R among infants of predominantly insensitive mothers. Caregiving quality in early life may influence the responsiveness of the sympathetic and parasympathetic branches of the ANS as well as the HPA axis. Consideration of the ANS and HPA axis systems together provides a fuller representation of adaptive versus maladaptive stress responses. The findings highlight the importance of supporting high quality caregiving in the early years of life, which is likely to promote later health. Copyright © 2014 Elsevier Ltd. All rights reserved.

Elevated urinary levels of kidney injury molecule-1 among Chinese factory workers exposed to trichloroethylene

PubMed Central

Vermeulen, Roel; Huang, Hanlin; Rothman, Nathaniel; Lan, Qing

2012-01-01

Epidemiological studies suggest that trichloroethylene (TCE) exposure may be associated with renal cancer. The biological mechanisms involved are not exactly known although nephrotoxicity is believed to play a role. Studies on TCE nephrotoxicity among humans, however, have been largely inconsistent. We studied kidney toxicity in Chinese factory workers exposed to TCE using novel sensitive nephrotoxicity markers. Eighty healthy workers exposed to TCE and 45 comparable unexposed controls were included in the present analyses. Personal TCE exposure measurements were taken over a 2-week period before urine collection. Ninety-six percent of workers were exposed to TCE below the current US Occupational Safety and Health Administration permissible exposure limit (100 ppm 8h TWA), with a mean (SD) of 22.2 (35.9) ppm. Kidney injury molecule-1 (KIM-1) and Pi-glutathione S transferase (GST) alpha were elevated among the exposed subjects as compared with the unexposed controls with a strong exposure-response association between individual estimates of TCE exposure and KIM-1 (P < 0.0001). This is the first report to use a set of sensitive nephrotoxicity markers to study the possible effects of TCE on the kidneys. The findings suggest that at relatively low occupational exposure levels a toxic effect on the kidneys can be observed. This finding supports the biological plausibility of linking TCE exposure and renal cancer. Abbreviations:GSTglutathione-S-transferaseKIM-1kidney injury molecule-1NAGN-acetyl-beta-(d)-glucosaminidaseOVMorganic vapour monitoringTCEtrichloroethyleneVEGFvascular endothelial growth factor. PMID:22665366

Rapid quantification of pharmaceuticals and pesticides in passive samplers using ultra high performance liquid chromatography coupled to high resolution mass spectrometry.

PubMed

Wille, Klaas; Claessens, Michiel; Rappé, Karen; Monteyne, Els; Janssen, Colin R; De Brabander, Hubert F; Vanhaecke, Lynn

2011-12-23

The presence of both pharmaceuticals and pesticides in the aquatic environment has become a well-known environmental issue during the last decade. An increasing demand however still exists for sensitive and reliable monitoring tools for these rather polar contaminants in the marine environment. In recent years, the great potential of passive samplers or equilibrium based sampling techniques for evaluation of the fate of these contaminants has been shown in literature. Therefore, we developed a new analytical method for the quantification of a high number of pharmaceuticals and pesticides in passive sampling devices. The analytical procedure consisted of extraction using 1:1 methanol/acetonitrile followed by detection with ultra-high performance liquid chromatography coupled to high resolution and high mass accuracy Orbitrap mass spectrometry. Validation of the analytical method resulted in limits of quantification and recoveries ranging between 0.2 and 20 ng per sampler sheet and between 87.9 and 105.2%, respectively. Determination of the sampler-water partition coefficients of all compounds demonstrated that several pharmaceuticals and most pesticides exert a high affinity for the polydimethylsiloxane passive samplers. Finally, the developed analytical methods were used to measure the time-weighted average (TWA) concentrations of the targeted pollutants in passive samplers, deployed at eight stations in the Belgian coastal zone. Propranolol, carbamazepine and seven pesticides were found to be very abundant in the passive samplers. These obtained long-term and large-scale TWA concentrations will contribute in assessing the environmental and human health risk of these emerging pollutants. Copyright © 2011 Elsevier B.V. All rights reserved.

A Bayesian Model and Stochastic Exposure (Dose) Estimation for Relative Exposure Risk Comparison Involving Asbestos-Containing Dropped Ceiling Panel Installation and Maintenance Tasks.

PubMed

Boelter, Fred W; Xia, Yulin; Persky, Jacob D

2017-09-01

Assessing exposures to hazards in order to characterize risk is at the core of occupational hygiene. Our study examined dropped ceiling systems commonly used in schools and commercial buildings and lay-in ceiling panels that may have contained asbestos prior to the mid to late 1970s. However, most ceiling panels and tiles do not contain asbestos. Since asbestos risk relates to dose, we estimated the distribution of eight-hour TWA concentrations and one-year exposures (a one-year dose equivalent) to asbestos fibers (asbestos f/cc-years) for five groups of workers who may encounter dropped ceilings: specialists, generalists, maintenance workers, nonprofessional do-it-yourself (DIY) persons, and other tradespersons who are bystanders to ceiling work. Concentration data (asbestos f/cc) were obtained through two exposure assessment studies in the field and one chamber study. Bayesian and stochastic models were applied to estimate distributions of eight-hour TWAs and annual exposures (dose). The eight-hour TWAs for all work categories were below current and historic occupational exposure limits (OELs). Exposures to asbestos fibers from dropped ceiling work would be categorized as "highly controlled" for maintenance workers and "well controlled" for remaining work categories, according to the American Industrial Hygiene Association exposure control rating system. Annual exposures (dose) were found to be greatest for specialists, followed by maintenance workers, generalists, bystanders, and DIY. On a comparative basis, modeled dose and thus risk from dropped ceilings for all work categories were orders of magnitude lower than published exposures for other sources of banned friable asbestos-containing building material commonly encountered in construction trades. © 2016 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

Dose-dependent increase in subjective symptoms among toluene-exposed workers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ukai, Hirohiko; Watanabe, Takao; Nakatsuka, Haruo

1993-02-01

A factory survey on dose-response relationship in toluene toxicity was conducted in 1985-1989 in four cities in China. The examination items consisted of personal diffusive sampling for TWA exposure measurement, questionnaires on subjective symptoms, hematology and serum biochemistry, and clinical examination including simple neurology tests. Hippuric acid was also determined in urine samples collected at the end of the shift. With selection criteria that (1) complete results were available on all study items and (2) valid toluene exposure data (i.e., toluene shared 90% or more of the exposure) were obtained for the exposed, 452 toluene-exposed workers (206 men and 246more » women; toluene exposure at 24.7 ppm as GM) and 517 nonexposed controls (246 men and 271 women) were selected. The subjective symptoms increased in close association with the intensity of exposure to toluene; the threshold concentration appeared to exist at 100 ppm in the case of symptoms during work, and it might be at 50-100 ppm when symptoms off work were evaluated. During the work with exposure at higher concentrations, various symptoms possibly related to CNS or local effects (e.g., eyes, nose, and throat) were complained, and dizziness and floating sensations were identified as typical symptoms with significant dose-response relationship. Several symptoms persisted off work, most of which were apparently related but not necessarily limited to CNS effects. Hematology and serum biochemistry were essentially negative. 46 refs., 4 figs., 6 tabs.« less

WISEA J114724.10-204021.3: A FREE-FLOATING PLANETARY MASS MEMBER OF THE TW HYA ASSOCIATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneider, Adam C.; Windsor, James; Cushing, Michael C.

We present WISEA J114724.10-204021.3, a young, low-mass, high-probability member of the TW Hya association (TWA). WISEA J114724.10-204021.3 was discovered based on its red AllWISE color ( W 1 − W 2 = 0.63 mag) and extremely red 2MASS J − K {sub S} color (>2.64 mag), the latter of which is confirmed with near-infrared photometry from the Visible and Infrared Survey Telescope for Astronomy Hemisphere Survey ( J − K {sub S} = 2.57 ± 0.03). Follow-up near-infrared spectroscopy shows a spectral type of L7 ± 1 as well as several spectroscopic indicators of youth. These include a peaked Hmore » -band shape and a steeper K -band slope, traits typically attributed to low surface gravity. The sky position, proper motion, and distance estimates of WISEA J114724.10-204021.3 are all consistent with membership in the ∼10 Myr old TWA. Using the age of the TWA and evolutionary models, we estimate the mass of WISEA J114724.10-204021.3 to be 5–13 M {sub Jup}, making it one of the youngest and lowest-mass free-floating objects yet discovered in the Solar neighborhood.« less

X-Rays Found From a Lightweight Brown Dwarf

NASA Astrophysics Data System (ADS)

2003-04-01

Using NASA's Chandra X-ray Observatory, scientists have detected X-rays from a low mass brown dwarf in a multiple star system, which is as young as 12 million years old. This discovery is an important piece in an increasingly complex picture of how brown dwarfs - and perhaps the very massive planets around other stars - evolve. Chandra's observations of the brown dwarf, known as TWA 5B, clearly resolve it from a pair of Sun-like stars known as TWA 5A. The system is about 180 light years from the Sun and a member of a group of about a dozen young stars in the southern constellation Hydra. The brown dwarf orbits the binary stars at a distance about 2.75 times that of Pluto's orbit around the Sun. This is first time that a brown dwarf this close to its parent star(s) has been resolved in X-rays. "Our Chandra data show that the X-rays originate from the brown dwarf's coronal plasma which is some 3 million degrees Celsius," said Yohko Tsuboi of Chuo University in Tokyo and lead author of the April 10th issue of Astrophysical Journal Letters paper describing these results. "The brown dwarf is sufficiently far from the primary stars that the reflection of X-rays is unimportant, so the X-rays must come the brown dwarf itself." TWA 5B is estimated to be only between 15 and 40 times the mass of Jupiter, making it one of the least massive brown dwarfs known. Its mass is rather near the currently accepted boundary (about 12 Jupiter masses) between planets and brown dwarfs. Therefore, these results may also have implications for very massive planets, including those that have been discovered as extrasolar planets in recent years. Brown Dwarf size comparison schematic Brown Dwarf size comparison schematic "This brown dwarf is as bright as the Sun today in X-ray light, while it is fifty times less massive than the Sun," said Tsuboi. "This observation, thus, raises the possibility that even massive planets might emit X-rays by themselves during their youth!" This research on TWA 5B also provides a link between an active X-ray state in young brown dwarfs (about 1 million years old) and a later, quieter period of brown dwarfs when they reach ages of 500 million to a billion years. Brown dwarfs are often referred to as "failed stars," as they are believed to be under the mass limit (about 80 Jupiter masses) needed to spark the nuclear fusion of hydrogen to helium, which characterizes traditional stars. Scientists hope to better understand the evolution of magnetic activity in brown dwarfs through the X-ray behavior. Chandra observed TWA 5B for about three hours on April 15, 2001, with its Advanced CCD Imaging Spectrometer (ACIS). Along with Chandra's mirrors, ACIS can achieve the angular resolution of a half arc second. TWA 5B Optical image of TWA 5B "This brown dwarf is about 200 times dimmer than the primary and located just two arcseconds away," said Gordon Garmire of Penn State University who led the ACIS team. "It's quite an achievement that Chandra was able to resolve it." Other members of the research team included Yoshitomo Maeda (Institute of Space and Astronautical Science, Kanagawa, Japan), Eric Feigelson, Gordon Garmire, George Chartas, and Koji Mori (Penn State University), and Steve Prado (Jet Propulsion Laboratory). NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program, and TRW, Inc., Redondo Beach, Calif., is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Mass., for the Office of Space Science at NASA Headquarters, Washington. Images and additional information about this result are available at: http://chandra.harvard.edu and http://chandra.nasa.gov

A practical approach to estimate emission rates of indoor air pollutants due to the use of personal combustible products based on small-chamber studies.

PubMed

Szulejko, Jan E; Kim, Ki-Hyun

2016-02-01

As emission rates of airborne pollutants are commonly measured from combusting substances placed inside small chambers, those values need to be re-evaluated for the possible significance under practical conditions. Here, a simple numerical procedure is investigated to extrapolate the chamber-based emission rates of formaldehyde that can be released from various combustible sources including e-cigarettes, conventional cigarettes, or scented candles to their concentration levels in a small room with relatively poor ventilation. This simple procedure relies on a mass balance approach by considering the masses of pollutants emitted from source and lost through ventilation under the assumption that mixing occurs instantaneously in the room without chemical reactions or surface sorption. The results of our study provide valuable insights into re-evaluation procedure of chamber data to allow comparison between extrapolated and recommended values to judge the safe use of various combustible products in confined spaces. If two scented candles with a formaldehyde emission rate of 310 µg h(-1) each were lit for 4 h in a small 20 m(3) room with an air change rate of 0.5 h(-1), then the 4-h (candle lit) and 8-h (up to 8 h after candle lighting) TWA [FA] were determined to be 28.5 and 23.5 ppb, respectively. This is clearly above the 8-h NIOSH recommended exposure limit (REL) time weighted average of 16 ppb. Copyright © 2015 Elsevier Ltd. All rights reserved.

Monitoring of formaldehyde in air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balmat, J.L.; Meadows, G.W.

1985-10-01

Any one of several monitoring methods, depending on requirement and circumstance, can be used to measure employee exposure to formaldehyde. Ordinarily, monitoring at DuPont is performed by sampling with impingers containing 1% aqueous sodium bisulfite or with silica gel tubes. The collected formaldehyde is measured spectrophotometrically after reaction with chromotropic acid. Results from studies on a selected number of formaldehyde monitoring methods reveal that reliable methods are available for area and personnel monitoring over both short term and long term. Accurate results are obtained from short-term monitoring (15 min at 1 L/min) with impingers of formaldehyde concentrations as low asmore » 0.14 ppm. The current studies show that long-term monitoring (8 hr at 0.5 L/min) can be performed accurately at concentrations as low as 0.05 ppm. Accurate results also are obtained from short-term monitoring (15 min at 500 mL/min) with silica gel tubes of concentrations as low as 0.11 ppm formaldehyde. Passive monitors provide the most convenient means of obtaining 8-hour time-weighted average (TWA) data. The Pro-Tek Formaldehyde Badge was demonstrated to reliably monitor formaldehyde concentrations varying from 0-0.5 ppm or 0-3 ppm. Investigation of the Lion Formaldemeter disclosed that instantaneous and accurate (+/- 5%) measurement of formaldehyde in air can be made over a concentration range of 0.3-5 ppm in the absence of other substances that are oxidizable in its fuel cell detector.« less

Assessment of indoor air quality at an electronic cigarette (Vaping) convention.

PubMed

Chen, Rui; Aherrera, Angela; Isichei, Chineye; Olmedo, Pablo; Jarmul, Stephanie; Cohen, Joanna E; Navas-Acien, Ana; Rule, Ana M

2017-12-29

E-cigarette (vaping) conventions are public events promoting electronic cigarettes, in which indoor use of e-cigarettes is allowed. The large concentration of people using e-cigarettes and poor air ventilation can result in indoor air pollution. In order to estimate this worst-case exposure to e-cigarettes, we evaluated indoor air quality in a vaping convention in Maryland (MD), USA. Real-time concentrations of particulate matter (PM 10 ) and real-time total volatile organic compounds (TVOCs), CO 2 and NO 2 concentrations were measured. Integrated samples of air nicotine and PM 10 concentrations were also collected. The number of attendees was estimated to range from 75 to 600 at any single observation time. The estimated 24-h time-weighted average (TWA) PM 10 was 1800 μg/m 3 , 12-fold higher than the EPA 24-h regulation (150 μg/m 3 ). Median (range) indoor TVOCs concentration was 0.13 (0.04-0.3) ppm. PM 10 and TVOC concentrations were highly correlated with CO 2 concentrations, indicating the high number of people using e-cigarettes and poor indoor air quality. Air nicotine concentration was 125 μg/m 3 , equivalent to concentrations measured in bars and nightclubs. E-cigarette aerosol in a vaping convention that congregates many e-cigarette users is a major source of PM 10 , air nicotine and VOCs, impairing indoor air quality. These findings also raise occupational concerns for e-cigarette vendors and other venue staff workers.

Accretion dynamics in pre-main sequence binaries

NASA Astrophysics Data System (ADS)

Tofflemire, B.; Mathieu, R.; Herczeg, G.; Ardila, D.; Akeson, R.; Ciardi, D.; Johns-Krull, C.

Binary stars are a common outcome of star formation. Orbital resonances, especially in short-period systems, are capable of reshaping the distribution and flows of circumstellar material. Simulations of the binary-disk interaction predict a dynamically cleared gap around the central binary, accompanied by periodic ``pulsed'' accretion events that are driven by orbital motion. To place observational constraints on the binary-disk interaction, we have conducted a long-term monitoring program tracing the time-variable accretion behavior of 9 short-period binaries. In this proceeding we present two results from our campaign: 1) the detection of periodic pulsed accretion events in DQ Tau and TWA 3A, and 2) evidence that the TWA 3A primary is the dominant accretor in the system.

Social Cognitive Career Theory, the Theory of Work Adjustment, and Work Satisfaction of Retirement-Age Adults

PubMed Central

Foley, Pamela F.; Lytle, Megan C.

2015-01-01

Despite a recent increase in the number of adults who work past traditional retirement age, existing theories of vocational behavior have not yet received adequate empirical support. In a large sample of adults age 60–87, we evaluated the relationship between theorized predictors of work satisfaction proposed by Social Cognitive Career Theory (SCCT), work satisfaction as a predictor of continued work, as proposed by the Theory of Work adjustment (TWA), as well as the influence of reported experiences of discrimination on these relationships. While the results supported most of the predicted relationships, the effects of discrimination were stronger than the variables proposed by either SCCT or TWA for the present sample. PMID:26101456

Acute respiratory effects and biomarkers of inflammation due to welding-derived nanoparticle aggregates.

PubMed

Dierschke, Katrin; Isaxon, Christina; Andersson, Ulla B K; Assarsson, Eva; Axmon, Anna; Stockfelt, Leo; Gudmundsson, Anders; Jönsson, Bo A G; Kåredal, Monica; Löndahl, Jakob; Pagels, Joakim; Wierzbicka, Aneta; Bohgard, Mats; Nielsen, Jörn

2017-07-01

Welders are exposed to airborne particles from the welding environment and often develop symptoms work-related from the airways. A large fraction of the particles from welding are in the nano-size range. In this study we investigate if the welders' airways are affected by exposure to particles derived from gas metal arc welding in mild steel in levels corresponding to a normal welding day. In an exposure chamber, 11 welders with and 10 welders without work-related symptoms from the lower airways and 11 non-welders without symptoms, were exposed to welding fumes (1 mg/m 3 ) and to filtered air, respectively, in a double-blind manner. Symptoms from eyes and upper and lower airways and lung function were registered. Blood and nasal lavage (NL) were sampled before, immediately after and the morning after exposure for analysis of markers of oxidative stress. Exhaled breath condensate (EBC) for analysis of leukotriene B4 (LT-B4) was sampled before, during and immediately after exposure. No adverse effects of welding exposure were found regarding symptoms and lung function. However, EBC LT-B4 decreased significantly in all participants after welding exposure compared to filtered air. NL IL-6 increased immediately after exposure in the two non-symptomatic groups and blood neutrophils tended to increase in the symptomatic welder group. The morning after, neutrophils and serum IL-8 had decreased in all three groups after welding exposure. Remarkably, the symptomatic welder group had a tenfold higher level of EBC LT-B4 compared to the two groups without symptoms. Despite no clinical adverse effects at welding, changes in inflammatory markers may indicate subclinical effects even at exposure below the present Swedish threshold limit (8 h TWA respirable dust).

Civamide cream 0.075% in patients with osteoarthritis of the knee: a 12-week randomized controlled clinical trial with a longterm extension.

PubMed

Schnitzer, Thomas J; Pelletier, Jean-Pierre; Haselwood, Doug M; Ellison, William T; Ervin, John E; Gordon, Richard D; Lisse, Jeffrey R; Archambault, W Tad; Sampson, Allan R; Fezatte, Heidi B; Phillips, Scott B; Bernstein, Joel E

2012-03-01

To evaluate the safety and efficacy of civamide cream 0.075% for the treatment of osteoarthritis (OA) of the knee. We conducted a 12-week, multicenter, randomized, double-blind study with a 52-week open-label extension. Patients with OA of the knee received either civamide cream 0.075% or a lower dose of civamide cream, 0.01%, as the control. The 3 co-primary endpoints in the double-blind study were the time-weighted average (TWA) of change from baseline to Day 84 in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale, the WOMAC physical function subscale, and the Subject Global Evaluation (SGE). In the 52-week open-label extension study, the Osteoarthritis Pain Score and SGE were assessed. A total of 695 patients were randomized to receive civamide cream 0.075% (n = 351) or civamide cream 0.01% (control; n = 344) in the double-blind study. Significance in favor of civamide cream 0.075% was achieved for the TWA for all 3 co-primary efficacy variables: WOMAC pain (p = 0.009), WOMAC physical function (p < 0.001), and SGE (p = 0.008); and at Day 84 for these 3 variables (p = 0.013, p < 0.001, and p = 0.049, respectively). These analyses accounted for significant baseline-by-treatment interactions. In the 52-week open-label extension, efficacy was maintained. Civamide cream 0.075% was well tolerated throughout the studies. These studies demonstrate the efficacy of civamide cream for up to 1 year of continuous use. Civamide cream, with its lack of systemic absorption, does not have the potential for serious systemic toxicity, in contrast to several other OA treatments.

Applying the Theory of Work Adjustment to Latino Immigrant Workers: An Exploratory Study.

PubMed

Eggerth, Donald E; Flynn, Michael A

2012-02-01

Blustein mapped career decision making onto Maslow's model of motivation and personality and concluded that most models of career development assume opportunities and decision-making latitude that do not exist for many individuals from low income or otherwise disadvantaged backgrounds. Consequently, Blustein argued that these models may be of limited utility for such individuals. Blustein challenged researchers to reevaluate current career development approaches, particularly those assuming a static world of work, from a perspective allowing for changing circumstances and recognizing career choice can be limited by access to opportunities, personal obligations, and social barriers. This article represents an exploratory effort to determine if the theory of work adjustment (TWA) might meaningfully be used to describe the work experiences of Latino immigrant workers, a group living with severe constraints and having very limited employment opportunities. It is argued that there is significant conceptual convergence between Maslow's hierarchy of needs and the work reinforcers of TWA. The results of an exploratory, qualitative study with a sample of 10 Latino immigrants are also presented. These immigrants participated in key informant interviews concerning their work experiences both in the United States and in their home countries. The findings support Blustein's contention that such workers will be most focused on basic survival needs and suggest that TWA reinforcers are descriptive of important aspects of how Latino immigrant workers conceptualize their jobs.

Applying the Theory of Work Adjustment to Latino Immigrant Workers: An Exploratory Study

PubMed Central

Eggerth, Donald E.; Flynn, Michael A.

2015-01-01

Blustein mapped career decision making onto Maslow’s model of motivation and personality and concluded that most models of career development assume opportunities and decision-making latitude that do not exist for many individuals from low income or otherwise disadvantaged backgrounds. Consequently, Blustein argued that these models may be of limited utility for such individuals. Blustein challenged researchers to reevaluate current career development approaches, particularly those assuming a static world of work, from a perspective allowing for changing circumstances and recognizing career choice can be limited by access to opportunities, personal obligations, and social barriers. This article represents an exploratory effort to determine if the theory of work adjustment (TWA) might meaningfully be used to describe the work experiences of Latino immigrant workers, a group living with severe constraints and having very limited employment opportunities. It is argued that there is significant conceptual convergence between Maslow’s hierarchy of needs and the work reinforcers of TWA. The results of an exploratory, qualitative study with a sample of 10 Latino immigrants are also presented. These immigrants participated in key informant interviews concerning their work experiences both in the United States and in their home countries. The findings support Blustein’s contention that such workers will be most focused on basic survival needs and suggest that TWA reinforcers are descriptive of important aspects of how Latino immigrant workers conceptualize their jobs. PMID:26345693

Occupational health concerns in the welding industry.

PubMed

Korczynski, R E

2000-12-01

The Workplace Safety and Health Branch initiated a proactive study in the welding industry in Manitoba. Eight welding companies participated in this study. Health concerns raised by welders were welders' flash, sore/red/teary eyes, headaches, nosebleeds, and a black mucous discharge from their nasal membrane. Most welders expressed concern regarding excessive smoke levels in the workplace and inadequate ventilation. Types of welding identified were MIG mild steel, MIG stainless steel, and TIG aluminum. Monitoring involved an assessment of noise levels, fume composition, and carbon monoxide and ozone concentrations. Metal analyses were according to National Institute for Occupational Safety and Health (NIOSH) Method 7300. Noise dosimeters used were the Quest model 100 and Micro 14 & 15. Carbon monoxide was monitored using the Gastech Model 4700 and ozone using the AID Portable Ozone Meter Model 560. In Manitoba, a hearing conservation program is required when the equivalent sound exposure level (normalized Lex 8-hr) exceeds 80 dBA-weighted. The American Conference of Governmental Industrial Hygienists' threshold limit value-time weighted average (ACGIH TLV-TWA) for iron is 5.0 mg/m3, manganese is 0.2 mg/m3, carbon monoxide is 25 ppm, and ozone is 0.05 ppm (heavy work), 0.08 ppm (moderate work), and 0.1 ppm (light work). Welders' personal exposures to manganese ranged from 0.01-4.93 mg/m3 (N = 42; AM = 0.5; GM = 0.2; SD +/- 0.9; GSD +/- 3.2) and to iron ranged from 0.04-16.29 mg/m3 (N = 42; AM = 3.0; GM = 1.4; SD +/- 3.5; GSD +/- 2.5). Noise exposures ranged from 79-98 dBA (N = 44; AM = 88.9; GM = 88.8; SD +/- 4.2; GSD +/- 1.0). Carbon monoxide levels were less than 5.0 ppm (at source) and ozone levels varied from 0.4-0.6 ppm (at source). Ventilation upgrades in the workplace were required in most welding shops. Only 7 percent of the welders wore respiratory protection. A hearing conservation program and hearing protection were required at all monitored workplaces.

Comparison of a direct-reading device to gravimetric methods for evaluating organic dust aerosols in an enclosed swine production environment.

PubMed

Taylor, C D; Reynolds, S J

2001-01-01

The production of livestock in enclosed facilities has become an accepted practice, driven by the need for increased efficiency. Exposure to organic dusts, containing various bioactive components, has been identified an important risk factor for the high rate of lung disease found among workers in these environments. Assessment of organic dust exposure requires technical skills and instrumentation not readily available to most agricultural enterprises. Development of a simple, cost-effective method for measuring organic dust levels would be useful in evaluating and controlling exposures in these environments. The objective of this study was to evaluate the usefulness of the direct reading MIE PDM-3 Miniram for estimating organic dust concentrations in enclosed swine production facilities. Responses from the MIE PDM-3 Miniram were compared to gravimetric methods for total and inhalable dust. Total dust determinations were conducted in accordance with the National Institute for Occupational Safety and Health (NIOSH) method 0500. Inhalable particulate mass (IPM) sampling was conducted using SKC brand IOM (Institute of Occupational Medicine) sampling cassettes, which meet the American Conference of Governmental Industrial Hygienists ACGIH criteria for inhalable dust sampling. This study design also allowed for the comparison of traditional total dust method to the IPM method, in collecting organic dusts in an agricultural setting. Fifteen sets of side-by-side samples (Miniram, total dust, and IPM) were collected over a period of six months in a swine confinement building. There were statistically significant differences in the results provided by the three sampling methods. Measurements for inhalable dust exceeded those for total dust in eleven of fifteen samples. The Miniram time-weighted average (TWA) response to the organic dust was always the lower of the three methods. A high degree of correlation was found among all three methods. The Miniram performed well under field conditions of varying temperature and humidity. The Miniram has the potential to predict the inhalable and total dust concentrations, assuming a correction factor for the organic dust being measured is applied.

Comparison of active and passive sampling strategies for the monitoring of pesticide contamination in streams

NASA Astrophysics Data System (ADS)

Assoumani, Azziz; Margoum, Christelle; Guillemain, Céline; Coquery, Marina

2014-05-01

The monitoring of water bodies regarding organic contaminants, and the determination of reliable estimates of concentrations are challenging issues, in particular for the implementation of the Water Framework Directive. Several strategies can be applied to collect water samples for the determination of their contamination level. Grab sampling is fast, easy, and requires little logistical and analytical needs in case of low frequency sampling campaigns. However, this technique lacks of representativeness for streams with high variations of contaminant concentrations, such as pesticides in rivers located in small agricultural watersheds. Increasing the representativeness of this sampling strategy implies greater logistical needs and higher analytical costs. Average automated sampling is therefore a solution as it allows, in a single analysis, the determination of more accurate and more relevant estimates of concentrations. Two types of automatic samplings can be performed: time-related sampling allows the assessment of average concentrations, whereas flow-dependent sampling leads to average flux concentrations. However, the purchase and the maintenance of automatic samplers are quite expensive. Passive sampling has recently been developed as an alternative to grab or average automated sampling, to obtain at lower cost, more realistic estimates of the average concentrations of contaminants in streams. These devices allow the passive accumulation of contaminants from large volumes of water, resulting in ultratrace level detection and smoothed integrative sampling over periods ranging from days to weeks. They allow the determination of time-weighted average (TWA) concentrations of the dissolved fraction of target contaminants, but they need to be calibrated in controlled conditions prior to field applications. In other words, the kinetics of the uptake of the target contaminants into the sampler must be studied in order to determine the corresponding sampling rate constants (Rs). Each constant links the mass of the a target contaminant accumulated in the sampler to its concentration in water. At the end of the field application, the Rs are used to calculate the TWA concentration of each target contaminant with the final mass of the contaminants accumulated in the sampler. Stir Bar Sorptive Extraction (SBSE) is a solvent free sample preparation technique dedicated to the analysis of moderately hydrophobic to hydrophobic compounds in liquid and gas samples. It is composed of a magnet enclosed in a glass tube coated with a thick film of polydimethysiloxane (PDMS). We recently developed the in situ application of SBSE as a passive sampling technique (herein named "Passive SBSE") for the monitoring of agricultural pesticides. The aim of this study is to perform the calibration of the passive SBSE in the laboratory, and to apply and compare this technique to active sampling strategies for the monitoring of 16 relatively hydrophobic to hydrophobic pesticides in streams, during 2 1-month sampling campaigns. Time-weighted averaged concentrations of the target pesticides obtained from passive SBSE were compared to the target pesticide concentrations of grab samples, and time-related and flow-dependent samples of the streams. Results showed passive SBSE as an efficient alternative to conventional active sampling strategies.

Theory of Gyrotron Traveling Wave Amplifiers at Harmonics of the Gyration Frequency

NASA Astrophysics Data System (ADS)

Li, Qiangfa

In developing gyrotrons at millimeter and submillimeter wavelengths, a means of operation at lower applied magnetic fields is desirable because of the size and weight of convetional magnets, and the expense and complexity of cryogenic magnets. This requirement can be met by operating the devices at higher harmonics of the electron gyration frequency. In the present work, a unified theory is developed for the gyrotron traveling wave amplifers (gyro-TWA) at harmonics of the gyration frequency, both in the nonlinear regime and in the linear regime. This theory can be applied to a wide class of waveguide cross sections, arbitrary harmonic number, any waveguide mode, and generalized electron beam model. The fields in the beam-field interaction region in the waveguide are expressed in the form of an infinite series of multipoles expanded around the guiding center of the electrons. A set of equations governing the nonlinear behavior of the gyro-TWA is derived. A general dispersion equation is derived both from that set of nonlinear equations by an iteration method and from plasma kinetic theory. The latter is employed to analyze gyro-TWA devices in a systematic and generalized manner. The Laplace transformation is introduced to allow inclusion of the initial values at the input end of the waveguide. From the linear theory it is found that for a gyrotron working at s-th gyration harmonic the electrons can interact only with the 2s-th order multipole field component. It is also found that a higher order waveguide mode is not always better than a lower order mode for the gyro-TWA working at higher harmonics. A novel out-ridged waveguide is proposed and analyzed for the use in gyrotrons. The prominent features of this new waveguide include simplicity of manufacture, freedom from local modes, good separation of lower order modes, high power handling ability, and high gain per unit length at higher gyration harmonics. A comparison of the gyro-TWAs with several different waveguide structures, such as the out-ridged, magnetron-type, rectangular and circular waveguides, is made through numerical examples of the gain-frequency curves computed from the linear kinetic theory.

Potassium channel KCNH2 K897T polymorphism and cardiac repolarization during exercise test: The Finnish Cardiovascular Study.

PubMed

Koskela, J; Laiho, J; KäHönen, M; Rontu, R; Lehtinen, R; Viik, J; Niemi, M; Niemelä, K; Kööbi, T; Turjanmaa, V; Pörsti, I; Lehtimäki, T; Nieminen, T

2008-01-01

Cardiac repolarization is regulated, in part, by the KCNH2 gene, which encodes a rapidly activating component of the delayed rectifier potassium channel. The gene expresses a functional single nucleotide polymorphism, K897T, which changes the biophysical properties of the channel. The objective of this study was to evaluate whether this polymorphism influences two indices of repolarization--the QT interval and T-wave alternans (TWA)--during different phases of a physical exercise test. The cohort consisted of 1,975 patients undergoing an exercise test during which on-line electrocardiographic data were registered. Information on coronary risk factors and medication was recorded. The 2690A>C nucleotide variation in the KCNH2 gene corresponding to the K897T amino acid change was analysed after polymerase chain reaction with allele-specific TaqMan probes. Among all subjects, the QTc intervals did not differ between the three genotype groups (p> or =0.31, RANOVA). Women with the CC genotype tended to have longer QT intervals during the exercise test, but the difference was statistically significant only at rest (p = 0.011, ANOVA). This difference was also detected when the analysis was adjusted for several factors influencing the QT interval. No statistically significant effects of the K897T polymorphism on TWA were observed among all subjects (p = 0.16, RANOVA), nor in men and women separately. The K897T polymorphism of the KCNH2 gene may not be a major genetic determinant for the TWA, but the influence of the CC genotype on QT interval deserves further research among women.

Perceptions of team members working in cleft services in the United kingdom: a pilot study.

PubMed

Scott, Julia K; Leary, Sam D; Ness, Andy R; Sandy, Jonathan R; Persson, Martin; Kilpatrick, Nicky; Waylen, Andrea E

2015-01-01

Cleft care provision in the United Kingdom has been centralized over the past 15 years to improve outcomes for children born with cleft lip and palate. However, to date, there have been no investigations to examine how well these multidisciplinary teams are performing. In this pilot study, a cross-sectional questionnaire surveyed members of all health care specialties working to provide cleft care in 11 services across the United Kingdom. Team members were asked to complete the Team Work Assessment (TWA) to investigate perceptions of team working in cleft services. The TWA comprises 55 items measuring seven constructs: team foundation, function, performance and skills, team climate and atmosphere, team leadership, and team identity; individual constructs were also aggregated to provide an overall TWA score. Items were measured using five-point Likert-type scales and were converted into percentage agreement for analysis. Responses were received from members of every cleft team. Ninety-nine of 138 cleft team questionnaires (71.7%) were returned and analyzed. The median (interquartile range) percentage of maximum possible score across teams was 75.5% (70.8, 88.2) for the sum of all items. Team performance and team identity were viewed most positively, with 82.0% (75.0, 88.2) and 88.4% (82.2, 91.4), respectively. Team foundation and leadership were viewed least positively with 79.0% (72.6, 84.6) and 76.6% (70.6, 85.4), respectively. Cleft team members perceive that their teams work well, but there are variations in response according to construct.

Airline competition : issues raised by consolidation proposals

DOT National Transportation Integrated Search

2001-02-01

In May 2000, United Airlines (United) proposed to acquire US Airways and divest part of those assets to create a new airline to be called DC Air. More recently, American Airlines (American) has proposed to purchase Trans World Airlines (TWA), along w...

Oxidative Stress Biomarkers in Exhaled Breath of Workers Exposed to Crystalline Silica Dust by SPME-GC-MS.

PubMed

Jalali, Mahdi; Zare Sakhvidi, Mohammad Javad; Bahrami, Abdulrahman; Berijani, Nima; Mahjub, Hussein

2016-01-01

Silicosis is considered an oxidative stress related disease that can lead to the development of lung cancer. In this study, our purpose was to analysis of volatile organic compounds (VOCs) in the exhaled breath of workers exposed to silica containing dust and compare peak area of these compounds with silicosis patients and healthy volunteers (smokers and nonsmokers) groups. In this cross sectional case-control study, the exhaled breath of 69 subjects including workers exposed to silica (n=20), silicosis patient (n=4), healthy non-smoker (n=20) and healthy smoker (n=25) were analyzed. We collected breath samples using 3-liter Tedlar bags. The VOCs were extracted with solid phase micro-extraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). Personal exposure intensity was measured according to NIOSH 7601 method. Respiratory parameters were measured using spirometry. Seventy percent and 100% of the exposures to crystalline silica dust exceeded from 8 h TWA ACGIH TLVs in case and positive control groups, respectively. A significant negative correlation was found between dust exposure intensity and FEV1/FVC when exposure and positive control groups were studied in a group (r2=-0.601, P<0.001). Totally, forty VOCs were found in all exhaled breath samples. Among the VOCs, the mean of peak area acetaldehyde, hexanal, nonanal, decane, pentad cane, 2-propanol and 3-hydroxy-2-butanone were higher in exhaled breath of the workers exposed to silica and silicosis patient compared to the healthy smoker and nonsmoker controls. In some cases the difference was significant (P<0.05). The analysis of some VOCs in exhaled breath of subjects is appropriate biomarker to determine of exposure to silica.

Measurement of respirable superabsorbent polyacrylate (SAP) dust by ethanol derivatization using gas chromatography-mass spectrometry (GC-MS) detection.

PubMed

McCormack, Paul; Lemmo, John S; Macomber, Margaret; Holcomb, Mark L; Lieckfield, Robert

2011-04-01

Superabsorbent polyacrylate (SAP) is an important industrial chemical manufactured primarily as sodium polyacrylate but occasionally as potassium salt. It has many applications owing to its intrinsic physical property of very high water absorption, which can be more than 100 times it own weight. SAP is commonly used in disposable diapers and feminine hygiene products and is known by a number of synonyms-sodium polyacrylate, superabsorbent polyacrylate (SAP), polyacrylate absorbent (PA), and superabsorbent material (SAM). Germany and The Netherlands have adopted a nonbinding scientific guideline value 0.05 mg/m³ (8-hr time-weighted average, TWA) as the maximum allowable workplace concentration for the respirable dust of SAP (<10 μm particle diameter). Three industry associations representing Europe, the United States, and Asia have adopted the German scientific guideline value of 0.05 mg/m³ (8-hr TWA) as a voluntary guideline. A new test method based on alcohol derivatization of the acrylate was developed and validated for the analysis of respirable superabsorbent polyacrylate dust collected on filter cassettes in the workplace environment. This method is an alternative to the commonly used sodium-based method, which is limited owing to potential interference by other sources of sodium from the workplace and laboratory environments. The alcohol derivatization method effectively eliminates sodium interference from several classes of sodium compounds, as shown by their purposeful introduction at two and six times the equivalent amount of SAP present in reference samples. The accuracy of the method, as determined by comparison with sodium analysis of known reference samples, was greater than 80% over the study range of 5-50 μg of SAP dust. The lower reporting limit of the method is 3.0 μg of SAP per sample, which is equivalent to 3 (μg/m³) for an 8-hr sampling period at the recommended flow rate of 2.2 L/min.

Anesthetic gas exposure in veterinary clinics.

PubMed

Korczynski, R E

1999-06-01

Concerns were raised by several workers from veterinary clinics in Manitoba, Canada, regarding potential exposure to isoflurane and halothane during anesthetic administration. There has been no guideline established for isoflurane by the American Conference of Governmental Industrial Hygienist (ACGIH) or a Permissible Exposure Limit by the Occupational Safety and Health Administration (OSHA) or a recommended exposure limit (REL) by the National Institute for Occupational Safety and Health (NIOSH). The ACGIH TLV-TWA for halothane is 50 ppm and NIOSH has established 2 ppm as a recommended level based on an one-hour sampling. OSHA has established no guideline for halothane. The Miran IB Portable Ambient Air Analyzer was used to conduct real-time sampling and to identify leaks during administration. All veterinary clinics inspected had installed the passive waste gas scavenging system. Ten clinics were each monitored during anesthetic gas delivery for one surgical procedure performed. Induction was 4 to 5 percent and maintenance 1.5 to 2.5 percent. Nine clinics were small animal practices and the tenth was an equine clinic. Veterinarians' personal exposures were higher than the assistants'. Veterinarians' personal exposures for isoflurane ranged from 1.3 to 13 ppm (AM = 5.3; SD +/- 2.7; GM = 4.6; GSD +/- 1.6) and for their assistants, personal exposures ranged from 1.2 to 9 ppm (AM = 4.7; SD +/- 2.5; GM = 3.9; GSD +/- 1.6). Veterinarians' personal exposures for halothane ranged from 0.7 to 12 ppm (AM = 4.2; SD +/- 3.6; GM = 2.9; GSD +/- 1.4) and for their assistants, personal exposures ranged from 0.4 to 3.2 ppm (AM = 1.8; SD +/- 1.0; GM = 1.5; GSD +/- 1.7). One clinic had significant leaks in the anesthetic gas delivery lines. Personal halothane exposure for the veterinarian at this clinic was 7.2 to 65 ppm (AM = 18.0; SD +/- 11.5; GM = 15.9; GSD +/- 1.8). Based on this study, worker exposures were acceptable. Peak exposures were recorded when the cuffed endotracheal tube was removed from the animal. Equipment leaks were minimal when the system was maintained at its optimum operating condition.

[Evoked potentials and psychometric tests in the diagnosis of subclinical neurological damage in a group of workers exposed to low concentrations of mercury vapor].

PubMed

Martínez Vázquez, C; Rodríguez Sáez, E; Gil Fernández, M; Torres Pombo, J; Rodríguez, M; Iglesias Groba, M T; Herves Beloso, C

1996-05-01

We study the effects of low concentrations of mercury vapour on the nervous system of a group of eleven workers of a chloroalkali plant exposed to it. Twenty-three non-exposed workers in the same factory were used as control group. We used clinical and analytic explorations, psychometric tests and evoked potentials to evaluate the subjects. The average Hg in urine of the exposed group was 41.74 micrograms/gr creatinine and the average of the non-exposed group as 9.71 mu/yr. In the exposed group the evoked potentials have found a slowing-down of conduction in all the nervous paths studied (optical, auditive and somatosensory) and in the latency of P300 wave, although this was not statistically significant compared to the control group. Of the psychometric test used, only Rey's Complex Figure Test showed deterioration in the visual memory subtest of the exposed group (p < 0.05) compared to the control group, although in Wechsler's digit span test lower scores were obtained which were close to being statistically significant comparing the averages of the two groups (0.05 < p < 0.051). Bearing in mind these results we think that the amounts of Hg in urine and TLV-TWA (50 micrograms/gr creatinine and 50 micrograms/m3 respectively) accepted by most authors as innocuous should be reduced.

Evaluation of occupational exposure to toxic metals released in the process of aluminum welding.

PubMed

Matczak, Wanda; Gromiec, Jan

2002-04-01

The objective of this study was to evaluate occupational exposure to welding fumes and its elements on aluminum welders in Polish industry. The study included 52 MIG/Al fume samples and 18 TIG/Al samples in 3 plants. Air samples were collected in the breathing zone of welders (total and respirable dust). Dust concentration was determined gravimetrically, and the elements in the collected dust were determined by AAS. Mean time-weighted average (TWA) concentrations of the welding dusts/fumes and their components in the breathing zone obtained for different welding processes were, in mg/m3: MIG/Al fumes mean 6.0 (0.8-17.8), Al 2.1 (0.1-7.7), Mg 0.2 (< 0.1-0.9), Mn 0.014 (0.002-0.049), Cu 0.011 (0.002-0.092), Zn 0.016 (0.002-0.14), Pb 0.009 (0.005-0.025), Cr 0.003 (0.002-0.007), and TIG/Al fumes 0.7 (0.3-1.4), Al 0.17 (0.07-0.50). A correlation has been found between the concentration of the main components and the fume/dust concentrations in MIG/Al and TIG/Al fumes. Mean percentages of the individual components in MIG/Al fumes/dusts were Al: 30 (9-56) percent; Mg: 3 (1-5.6) percent; Mn: 0.2 (0.1-0.3) percent; Cu: 0.2 (< 0.1-1.8) percent; Zn: 0.2 (< 0.1-0.8) percent; Pb: 0.2 (< 0.1-1) percent; Cr: < 0.1 percent. The proportion of the respirable fraction in the fumes and their constituents varied between 10 percent and 100 percent. The results showed that MIG/Al fumes concentration was 1.2 times higher than the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV), and the index of the combined exposure to the determined agents was 2.3 (0.4-8.0), mostly because of high Al2O3 contribution. The background concentrations of the components (ca. 5-10 times lower than those in the breathing zone of the welders) did not exceed the Polish MAC value. The elemental composition of total and respirable fume/dust may differ considerably depending on welding methods, the nature of welding-related operations, and work environment conditions.

Aviation Safety: FAA Has Begun Efforts to Make Data More Publicly Available

DOT National Transportation Integrated Search

1997-04-25

Public concern about the safety of the nation's aviation system escalated : following the crashes of ValuJet flight 592 and TWA flight 800. The Congress : and the public expressed interest in having the Federal Aviation Administration : (FAA) publish...

Time-Integrated Monitoring of Dioxin-Like Polychlorinated Biphenyls (dl-PCBs) in Aquatic Environments using the Ceramic Toximeter and the CALUX Bioassay

PubMed Central

Addeck, Amr; Croes, Kim; Van Langenhove, Kersten; Denison, Michael S.; Afify, Ahmed S.; Gao, Yue; Elskens, Marc; Baeyens, Willy

2015-01-01

Ceramic passive samplers or toximeters (packed with active carbon 1% w/w on celite), in combination with the CALUX bioassay have been used as a time-integrated monitoring technique for dissolved dioxin-like PCBs in urban and industrial wastewaters. The technique showed to be reliable during laboratory experiments: (1) PCB-126 amounts extracted from the passive samplers increased linearly with the time of exposure and (2) PCB-126 concentrations calculated from the amounts accumulated by the passive samplers were in agreement with their concentrations in the testing solution. Afterwards the toximeters were applied in the field. Two sampling sites located in Egypt were chosen: the Belbeis drainage canal, and the EMAK paper mill. A total of 18 ceramic toximeters were exposed to the wastewater in both sampling sites for a maximum period of 4 weeks. Two samplers were collected weekly from each site to monitor the increase in target analytes over time. Extracts were analyzed using the CALUX bioassay and the total dioxin-like PCB toxicity was reported for the aqueous phase (water column), as well as the solid phase (sediment and sludge) in both sampling sites. The time-weighted average concentration (TWA) of dl-PCBs in wastewater of the paper mill during the sampling period ranged between 7.1 and 9.1 pg-BEQ L-1, while that of the drainage canal ranged between 9.5 and 12.2 pg-BEQ L-1. The dl-PCBs in the fibrous sludge (paper mill) and bottom sediment (drainage canal) were 0.5 and 0.4 pg-BEQ g-1 dry-weight, respectively. The organic-carbon normalized partition coefficients between sediment and water (log Koc) for the paper mill and the canal were 2.4 and 4.3, respectively. PMID:24468390

Field Validation of POCIS for Monitoring at Underwater Munitions Sites.

PubMed

Rosen, Gunther; Lotufo, Guilherme R; George, Robert D; Wild, Bill; Rabalais, Lauren K; Morrison, Shane; Belden, Jason B

2018-04-24

The present study evaluated Polar Organic Chemical Integrative Samplers (POCIS) for quantification of conventional munitions constituents (MC), including trinitrotoluene (TNT), aminodinitrotoluenes, diaminonitrotoluenes, dinitrotoluene, and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a field setting. POCIS were deployed at varying distances from the commonly used explosive formulation Composition B (39.5% TNT, 59.5% RDX, 1% wax) in an embayment of Santa Rosa Sound (Florida, USA). Time-weighted averaged (TWA) water concentrations from a 13-day deployment ranged from 9-103 ng/L for TNT and RDX approximately 0.3 to 2 m from the source. Concentrations decreased with increasing distance from the source to below quantitation limits (5-7 ng/L) at stations greater than 2 m away. Moderate biofouling of POCIS membranes after 13-d led to a subsequent effort to quantify potential effects of biofouling on sampling rate for MC. After biofouling was allowed to occur for periods of 0, 7, 14 or 28 days at the field site, POCIS were transferred to aquaria spiked with MC. No significant differences in uptake of TNT or RDX were observed across a gradient of biofouling presence, although mass of fouling organisms on the membranes was statistically greater for the 28-d field exposure. The present study verified the high sensitivity and integrative nature of POCIS for relevant MC potentially present in aquatic environments, indicating that application at underwater military munitions sites may be useful for ecological risk assessment. This article is protected by copyright. All rights reserved This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Cardiovascular and cortisol reactivity and habituation to a virtual reality version of the Trier Social Stress Test: a pilot study.

PubMed

Jönsson, Peter; Wallergård, Mattias; Osterberg, Kai; Hansen, Ase Marie; Johansson, Gerd; Karlson, Björn

2010-10-01

The Trier Social Stress Test (TSST) is a widely used protocol to induce stress in laboratory settings. Briefly, in the TSST, the test participant is asked to hold a speech and to do an arithmetic task in front of an audience. In the present pilot study, we examined endocrine and autonomic reactivity and habituation to repeated stress provocations using a virtual reality (VR) version of TSST. The VR system was a CAVE™ system with three rear projected walls (4 m×3 m), and one floor projection. The system also included a head tracking system and passive stereoscopy. The virtual audience consisted of one woman, and two men. Ten healthy men, mean age 28.3 years (24-38 years), were confronted with the test twice (1 week between sessions), during which salivary cortisol, heart rate (HR), high frequency heart rate variability (HF-HRV, parasympathetic activity), and T-wave amplitude (TWA, suggested to be related to sympathetic influence on myocardial performance) were assessed. Cortisol secretion showed a marked increase (88% vs. baseline) during the first stress provocation, but habituated in the second session. The magnitude of HR and TWA reactivity during stress provocation was approximately the same at both sessions, implying a stable increase in sympathetic activity. Heart rate showed a maximum increase of 40% at the first session, and 32% at the second. TWA showed a maximum decrease of 42% at the first session, and 39% at the second. The results resemble those obtained in prior studies using the real-life TSST. If these results can be replicated with larger samples, VR technology may be used as a simple and standardized tool for social stress induction in experimental settings. Copyright © 2010 Elsevier Ltd. All rights reserved.

Keck Adaptive Optics Imaging of Nearby Young Stars: Detection of Close Multiple Systems

NASA Astrophysics Data System (ADS)

Brandeker, Alexis; Jayawardhana, Ray; Najita, Joan

2003-10-01

Using adaptive optics on the Keck II 10 m telescope on Mauna Kea, we have surveyed 24 of the nearest young stars known in search of close companions. Our sample includes members of the MBM 12 and TW Hydrae young associations and the classical T Tauri binary UY Aurigae in the Taurus star-forming region. We present relative photometry and accurate astrometry for 10 close multiple systems. The multiplicity frequency in the TW Hydrae and MBM 12 groups are high in comparison to other young regions, although the significance of this result is low because of the small number statistics. We resolve S18 into a triple system, including a tight 63 mas (projected separation of 17 AU at a distance of 275 pc) binary, for the first time, with a hierarchical configuration reminiscent of VW Chamaeleontis and T Tauri. Another tight binary in our sample-TWA 5Aab (54 mas or 3 AU at 55 pc)-offers the prospect of dynamical mass measurement using astrometric observations within a few years and thus could be important for testing pre-main-sequence evolutionary models. Our observations confirm with 9 σ confidence that the brown dwarf TWA 5B is bound to TWA 5A. We find that the flux ratio of UY Aur has changed dramatically, by more than a magnitude in the H band, possibly as a result of variable extinction. With the smaller flux difference, the system may once again become detectable as an optical binary, as it was at the time of its discovery in 1944. Taken together, our results demonstrate that adaptive optics on large telescopes is a powerful tool for detecting tight companions and thus exploring the frequency and configurations of close multiple systems.

Detection and evaluation of ventricular repolarization alternans: an approach to combined ECG, thoracic impedance, and beat-to-beat heart rate variability analysis.

PubMed

Kriščiukaitis, Algimantas; Šimoliūnienė, Renata; Macas, Andrius; Petrolis, Robertas; Drėgūnas, Kęstutis; Bakšytė, Giedrė; Pieteris, Linas; Bertašienė, Zita; Žaliūnas, Remigijus

2014-01-01

Beat-to-beat alteration in ventricles repolarization reflected by alternans of amplitude and/or shape of ECG S-T,T segment (TWA) is known as phenomena related with risk of severe arrhythmias leading to sudden cardiac death. Technical difficulties have caused limited its usage in clinical diagnostics. Possibilities to register and analyze multimodal signals reflecting heart activity inspired search for new technical solutions. First objective of this study was to test whether thoracic impedance signal and beat-to-beat heart rate reflect repolarization alternans detected as TWA. The second objective was revelation of multimodal signal features more comprehensively representing the phenomena and increasing its prognostic usefulness. ECG, and thoracic impedance signal recordings made during 24h follow-up of the patients hospitalized in acute phase of myocardial infarction were used for investigation. Signal morphology variations reflecting estimates were obtained by the principal component analysis-based method. Clinical outcomes of patients (survival and/or rehospitalization in 6 and 12 months) were compared to repolarization alternans and heart rate variability estimates. Repolarization alternans detected as TWA was also reflected in estimates of thoracic impedance signal shape and variation in beat-to-beat heart rate. All these parameters showed correlation with clinical outcomes of patients. The strongest significant correlation showed magnitude of alternans in estimates of thoracic impedance signal shape. The features of ECG, thoracic impedance signal and beat-to-beat variability of heart rate, give comprehensive estimates of repolarization alternans, which correlate, with clinical outcomes of the patients and we recommend using them to improve diagnostic reliability. Copyright © 2014 Lithuanian University of Health Sciences. Production and hosting by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

The Young L Dwarf 2MASS J11193254-1137466 Is a Planetary-mass Binary

NASA Astrophysics Data System (ADS)

Best, William M. J.; Liu, Michael C.; Dupuy, Trent J.; Magnier, Eugene A.

2017-07-01

We have discovered that the extremely red, low-gravity L7 dwarf 2MASS J11193254-1137466 is a 0.″14 (3.6 au) binary using Keck laser guide star adaptive optics imaging. 2MASS J11193254-1137466 has previously been identified as a likely member of the TW Hydrae Association (TWA). Using our updated photometric distance and proper motion, a kinematic analysis based on the BANYAN II model gives an 82% probability of TWA membership. At TWA’s 10 ± 3 Myr age and using hot-start evolutionary models, 2MASS J11193254-1137466AB is a pair of {3.7}-0.9+1.2 {M}{Jup} brown dwarfs, making it the lowest-mass binary discovered to date. We estimate an orbital period of {90}-50+80 years. One component is marginally brighter in K band but fainter in J band, making this a probable flux-reversal binary, the first discovered with such a young age. We also imaged the spectrally similar TWA L7 dwarf WISEA J114724.10-204021.3 with Keck and found no sign of binarity. Our evolutionary model-derived {T}{eff} estimate for WISEA J114724.10-204021.3 is ≈230 K higher than for 2MASS J11193254-1137466AB, at odds with the spectral similarity of the two objects. This discrepancy suggests that WISEA J114724.10-204021.3 may actually be a tight binary with masses and temperatures very similar to 2MASS J11193254-1137466AB, or further supporting the idea that near-infrared spectra of young ultracool dwarfs are shaped by factors other than temperature and gravity. 2MASS J11193254-1137466AB will be an essential benchmark for testing evolutionary and atmospheric models in the young planetary-mass regime.

Benchmarking of a T-wave alternans detection method based on empirical mode decomposition.

PubMed

Blanco-Velasco, Manuel; Goya-Esteban, Rebeca; Cruz-Roldán, Fernando; García-Alberola, Arcadi; Rojo-Álvarez, José Luis

2017-07-01

T-wave alternans (TWA) is a fluctuation of the ST-T complex occurring on an every-other-beat basis of the surface electrocardiogram (ECG). It has been shown to be an informative risk stratifier for sudden cardiac death, though the lack of gold standard to benchmark detection methods has promoted the use of synthetic signals. This work proposes a novel signal model to study the performance of a TWA detection. Additionally, the methodological validation of a denoising technique based on empirical mode decomposition (EMD), which is used here along with the spectral method, is also tackled. The proposed test bed system is based on the following guidelines: (1) use of open source databases to enable experimental replication; (2) use of real ECG signals and physiological noise; (3) inclusion of randomized TWA episodes. Both sensitivity (Se) and specificity (Sp) are separately analyzed. Also a nonparametric hypothesis test, based on Bootstrap resampling, is used to determine whether the presence of the EMD block actually improves the performance. The results show an outstanding specificity when the EMD block is used, even in very noisy conditions (0.96 compared to 0.72 for SNR = 8 dB), being always superior than that of the conventional SM alone. Regarding the sensitivity, using the EMD method also outperforms in noisy conditions (0.57 compared to 0.46 for SNR=8 dB), while it decreases in noiseless conditions. The proposed test setting designed to analyze the performance guarantees that the actual physiological variability of the cardiac system is reproduced. The use of the EMD-based block in noisy environment enables the identification of most patients with fatal arrhythmias. Copyright © 2017 Elsevier B.V. All rights reserved.

Asbestos fiber release from the brake pads of overhead industrial cranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, J.W.; Plisko, M.J.; Balzer, J.L.

The purpose of this evaluation was to determine the actual contribution of airborne asbestos fibers to the work environment from the operation of overhead cranes and hoists that use asbestos composition brake pads. The evaluation was conducted in a working manufacturing facility. Other potential sources of asbestos were accounted for by visual inspection and background air monitoring. An overhead crane assembly comprised of a trolley and two hoists was employed for this study. The crane was operated for two consecutive eight-hour shifts representative of a heavy-duty cycle. Forty-four personal and area air samples were collected during the assessment. Asbestos fibersmore » were analyzed for by phase contrast (NIOSH 7400), and transmission electron (NIOSH 7402) microscopy methods. Eight-hour time-weighted average (TWA) asbestos fiber concentrations ranges from <0.005 to 0.011 fibers/cc (PCM), and <0.0026 to <0.0094f/cc (TEM). There were no asbestos fibers detected by the TEM method from air samples collected during the operation of the cranes.« less

Asbestos fiber release from the brake pads of overhead industrial cranes.

PubMed

Spencer, J W; Plisko, M J; Balzer, J L

1999-06-01

The purpose of this evaluation was to determine the actual contribution of airborne asbestos fibers to the work environment from the operation of overhead cranes and hoists that use asbestos composition brake pads. The evaluation was conducted in a working manufacturing facility. Other potential sources of asbestos were accounted for by visual inspection and background air monitoring. An overhead crane assembly comprised of a trolley and two hoists was employed for this study. The crane was operated for two consecutive eight-hour shifts representative of a heavy-duty cycle. Forty-four personal and area air samples were collected during the assessment. Asbestos fibers were analyzed for by phase contrast (NIOSH 7400), and transmission electron (NIOSH 7402) microscopy methods. Eight-hour time-weighted average (TWA) asbestos fiber concentrations ranged from < 0.005 to 0.011 fibers/cc (PCM), and < 0.0026 to < 0.0094 f/cc (TEM). There were no asbestos fibers detected by the TEM method from air samples collected during the operation of the cranes.

29 CFR 1910.1001 - Asbestos.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... The designation of a material as “PACM” may be rebutted pursuant to paragraph (j)(8) of this section... level as demonstrated by a statistically valid protocol; and (C) The equivalent method is documented and... PACM are in excess of the TWA and/or excursion limit prescribed in paragraph (c) of this section. (2...

29 CFR 1910.1001 - Asbestos.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... The designation of a material as “PACM” may be rebutted pursuant to paragraph (j)(8) of this section... level as demonstrated by a statistically valid protocol; and (C) The equivalent method is documented and... PACM are in excess of the TWA and/or excursion limit prescribed in paragraph (c) of this section. (2...

Comparing REACH Chemical Safety Assessment information with practice-a case-study of polymethylmethacrylate (PMMA) in floor coating in The Netherlands.

PubMed

Spee, Ton; Huizer, Daan

2017-10-01

On June 1st, 2007 the European regulation on Registration, Evaluation and Restriction of Chemical substances (REACH) came into force. Aim of the regulation is safe use of chemicals for humans and for the environment. The core element of REACH is chemical safety assessment of chemicals and communication of health and safety hazards and risk management measures throughout the supply chain. Extended Safety Data Sheets (Ext-SDS) are the primary carriers of health and safety information. The aim of our project was to find out whether the actual exposure to methyl methacrylate (MMA) during the application of polymethylmethacrylate (PMMA) in floor coatings as assessed in the chemical safety assessment, reflect the exposure situations as observed in the Dutch building practice. Use of PMMA flooring and typical exposure situations during application were discussed with twelve representatives of floor laying companies. Representative situations for exposure measurements were designated on the basis of this inventory. Exposure to MMA was measured in the breathing zone of the workers at four construction sites, 14 full shift samples and 14 task based samples were taken by personal air sampling. The task-based samples were compared with estimates from the Targeted Risk Assessment Tool (v3.1) of the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC-TRA) as supplied in the safety assessment from the manufacturer. For task-based measurements, in 12 out of 14 (86%) air samples measured exposure was higher than estimated exposure. Recalculation with a lower ventilation rate (50% instead of 80%) together with a higher temperature during mixing (40°C instead of 20°C) in comparison with the CSR, reduced the number of underestimated exposures to 10 (71%) samples. Estimation with the EMKG-EXPO-Tool resulted in unsafe exposure situations for all scenarios, which is in accordance with the measurement outcomes. In indoor situations, 5 out of 8 full shift exposures (62%) to MMA were higher than the Dutch occupational exposure limit of 205mg/m 3 (8h TWA), which equals the DNEL. For semi-enclosed situations this was 1 out of 6 (17%). Exposures varied from 31 to 367mg/m 3 . The results emphasize that ECETOC-TRA exposure estimates in poorly controlled situations need better underpinning. Copyright © 2017 Elsevier GmbH. All rights reserved.

18. Photographic copy of photograph of south and east elevations ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

18. Photographic copy of photograph of south and east elevations taken on March 22, 1957. Photographer unknown. Original photograph property of the City of Philadelphia, Division of Aviation. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

17. Photographic copy of photograph of north elevation taken on ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

17. Photographic copy of photograph of north elevation taken on March 22, 1957, photographer unknown. Original photograph property of the City of Philadelphia. Division of Aviation. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

22. Photographic copy of photograph of interior of hangar looking ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. Photographic copy of photograph of interior of hangar looking west taken on March 22, 1957. Photographer unknown. Original photograph property of the City of Philadelphia, Division of Aviation. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

21. Photographic copy of photograph of interior of hangar looking ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

21. Photographic copy of photograph of interior of hangar looking east taken on March 22, 1957. Photographer unknown. Original photograph property of the City of Philadelphia, Division of Aviation. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

26. Photographic copy of Second Floor Plan (The Ballinger Company, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

26. Photographic copy of Second Floor Plan (The Ballinger Company, April 12, 1955), In files of the City of Philadelphia. Division of Aviation, Terminal E. Philadelphia International Airport. Reprinted with permission of Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

23. Photographic copy of photograph of interior of hangar looking ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. Photographic copy of photograph of interior of hangar looking south taken on March 22, 1957. Photographer unknown. Original photograph property of the City of Philadelphia, Division of Aviation. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

20. Photographic copy of photograph of roof suspender system taken ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

20. Photographic copy of photograph of roof suspender system taken on March 22, 1957. Photographer unknown. Original photograph property of the City of Philadelphia, Division of Aviation. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

25. Photographic copy of First Floor Plan (The Ballinger Company, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

25. Photographic copy of First Floor Plan (The Ballinger Company, April 12, 1955). In files of the City of Philadelphia, Division of Aviation, Terminal E, Philadelphia International Airport. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

28. Photographic copy of North, South, East Elevation (The Ballinger ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. Photographic copy of North, South, East Elevation (The Ballinger Company, April 12, 1955). In files of the City of Philadelphia. Division of Aviation, Terminal E, Philadelphia International Airport. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

24. Photographic copy of photograph of mezzanine, interior of hangar, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

24. Photographic copy of photograph of mezzanine, interior of hangar, taken on March 22, 1957. Photographer unknown. Original photograph property of the City of Philadelphia, Division of Aviation. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

30. Photographic copy of Wall Sections and Details (The Ballinger ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

30. Photographic copy of Wall Sections and Details (The Ballinger Company, April 12, 1955). In files of the City of Philadelphia, Division of Aviation, Terminal E. Philadelphia International Airport Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

Validation of Passive Sampling Devices for Monitoring of Munitions Constituents in Underwater Environments

DTIC Science & Technology

2017-06-30

Research and Development Program [SERDP] project #ER-2542) into the canister would provide enhancement of the quantitative estimation of the TWA...7 4. Advantages and limitations compared to other sampling techniques...Department of Defense EOD Explosive Ordnance Disposal EPA United States Environmental Protection Agency EQL Environmental Quantitation Limit EST

Trans World Airlines, Inc., Castleton, Inc., near Greater Cincinnati Airport, Covington, Kentucky, January 12, 1955.

DOT National Transportation Integrated Search

1955-07-08

At 0904, January 12, 1955, a Trans World Airlines Martin 202A, N 93211, and a Douglas DC-3C, N 999B, owned by Castleton, Inc., collided near the Greater Cincinnati Airport approximately two minutes after takeoff of the TWA flight. All 13 persons aboa...

Comprehension Strategy Instruction for Two Students with Attention-Related Disabilities

ERIC Educational Resources Information Center

Hedin, Laura R.; Mason, Linda H.; Gaffney, Janet S.

2011-01-01

Many students struggle to maintain the attention needed to comprehend while reading. One 4th-grade student and 5th-grade student, both with poor comprehension and attention-related disabilities, were taught to use a proven systematic reading comprehension strategy, TWA (Think Before Reading, Think While Reading, Think After Reading), when reading…

Employment type, workplace interpersonal conflict, and insomnia: a cross-sectional study of 37,646 employees in Japan.

PubMed

Sakurai, Kenji; Nakata, Aknori; Ikeda, Tomoko; Otsuka, Yasumasa; Kawahito, Junko

2014-01-01

This study explored whether workplace interpersonal conflict (WIC) is associated with insomnia, and whether the relationship between WIC and insomnia differs across different employment groups. A total of 37,646 Japanese full-time employees participated in a cross-sectional survey. Employment types included permanent employment and 2 forms of temporary employment: direct-hire and temporary work agent (TWA). Insomnia symptoms, including difficulty initiating sleep, difficulty maintaining sleep, and early morning awakening were measured. Insomnia was defined as having experienced 1 or more of these symptoms on ≥3 nights per week over the past 12 months. Results showed that WIC was significantly associated with an increased risk of insomnia (odds ratio OR = 1.63; 95% confidence interval CI = 1.55-1.71), controlling for confounders. However, the relationship between WIC and the risk of insomnia was significantly stronger for TWAs than for permanent employees (OR = 1.97; 95% CI = 1.13-3.45). A frequent exposure to WIC may increase the risk of insomnia, particularly for TWAs.

Employment Type, Workplace Interpersonal Conflict, and Insomnia: A Cross-sectional Study of 37,646 Employees in Japan

PubMed Central

Sakurai, Kenji; Nakata, Aknori; Ikeda, Tomoko; Otsuka, Yasumasa; Kawahito, Junko

2015-01-01

This study explored whether workplace interpersonal conflict (WIC) is associated with insomnia, and whether the relationship between WIC and insomnia differs across different employment groups. A total of 37,646 Japanese full-time employees participated in a cross-sectional survey. Employment types included permanent employment and 2 forms of temporary employment: direct-hire and temporary work agent (TWA). Insomnia symptoms, including difficulty initiating sleep, difficulty maintaining sleep, and early morning awakening were measured. Insomnia was defined as having experienced 1 or more of these symptoms on ≥3 nights per week over the past 12 months. Results showed that WIC was significantly associated with an increased risk of insomnia (odds ratio OR = 1.63; 95% confidence interval CI = 1.55–1.71), controlling for confounders. However, the relationship between WIC and the risk of insomnia was significantly stronger for TWAs than for permanent employees (OR = 1.97; 95% CI = 1.13–3.45). A frequent exposure to WIC may increase the risk of insomnia, particularly for TWAs. PMID:23930793

Chronic psychological effects of exposure to mercury vapour among chlorine-alkali plant workers.

PubMed

Pranjić, N; Sinanović, O; Jakubović, R

2003-01-01

Quantitative assessment of nervous system function is essential in characterising the nature and extent of impairment in individuals experiencing symptoms following work-place mercury vapour exposure. The purpose of this study was the application of standardised tests of behavioural, psychomotor and memory function to understand the neuropsychological effects of mercury in occupationally exposed chlorine-alkali plant workers. The study comprised 45 workers at a chlorine-alkali plant with the mean age of 39.36 +/- 5.94 years, who had been exposed to daily inhalation of mercury vapour over long-term employment of 16.06 +/- 4.29 years. The cumulative mercury index was 155.32 +/- 95.02 micrograms/g creatinine, the mean of urinary mercury concentrations on the first day of the study was 119.50 +/- 157.24 micrograms/g creatinine, and the mean of urinary mercury concentrations 120 days after cessation of exposure was 21.70 +/- 26.07 micrograms/g creatinine. The analysis included tests of behavioural, psychomotor and memory function. The behavioural test battery consisted of: Environmental Worry Scale (EWS), Minnesota Modified Personal Inventory (MMPI-2), Purdue standard 25 minute test, and adapted, 10 minutes test, Bender's Visual-Motor Gestalt test (BGT), and Eysenck Personality Inventory (EPQ). The data were compared to a control group of 32 not directly exposed workers. In the mercury vapour exposed workers with relatively high level exposure to inorganic mercury vapour (TWA/TLV = 0.12 mg/m3/0.025 mg/m3) we identified somatic depression-hypochondria symptoms with higher scores for scales: hysteria (P < 0.001), schizoid and psycho-asthenia (MMPI-2). The mercury-exposed workers had introvert behaviour (EPQ, MMPI-2). The cognitive disturbances in mercury-exposed workers were identified as: concentration difficulty, psychomotor, perceptual and motor coordination disturbances, and brain effects. We identified fine tremor of the hands in 34 out of 45 mercury-exposed workers (BGT). The results point to a relationship between the duration of mercury exposure and the long-term, probably irreversible, psychological disturbances.

What Are the Risk Factors and Complications Associated With Intraoperative and Postoperative Fractures in Total Wrist Arthroplasty?

PubMed

Wagner, Eric R; Srnec, Jason J; Mehrotra, Kapil; Rizzo, Marco

2017-11-01

Total wrist arthroplasty (TWA) can relieve pain and preserve some wrist motion in patients with advanced wrist arthritis. However, few studies have evaluated the risks and outcomes associated with periprosthetic fractures around TWAs. (1) What is the risk of intraoperative and postoperative fractures after TWAs? (2) What factors are associated with increased risk of intraoperative and postoperative fracture after TWAs? (3) What is the fracture-free and revision-free survivorship of TWAs among patients who sustained an intraoperative fracture during the index TWA? At one institution during a 40-year period, 445 patients underwent primary TWAs. Of those, 15 patients died before 2 years and 5 were lost to followup, leaving 425 patients who underwent primary TWAs with a minimum of 2-year followup. The primary diagnosis for the TWA included osteoarthritis ([OA] 5%), inflammatory arthritis (90%), and posttraumatic arthritis (5%). Indications for TWA included pancarpal arthritis combined with marked pain and loss of wrist function. The mean age of the patients was 57 years, BMI was 26 kg/m 2 , and 73% were females. Six different implants were used during the 40-year period. Mean followup was 10 years (range, 2-18 years). Intraoperative fractures occurred in nine (2%) primary TWAs, while postoperative fractures occurred after eight (2%) TWAs. After analyzing demographics, comorbidities, and surgical factors, intraoperative fractures were found to be associated with only age at surgery (hazard ratio [HR], 1.10; 95% CI, 1.03-1.20; p = 0.006) and use of a bone graft (HR, 5.80; 95% CI, 1.18-23.08; p = 0.03). No factors were found to be associated with increased risk of postoperative fractures; specifically, intraoperative fracture was not associated with subsequent fracture development. The 5-, 10-, and 15-year Kaplan-Meier survival rates free of postoperative fracture were 99%, 98%, and 95%, respectively. The 5- and 10-year revision-free survival rates after intraoperative fracture were 88% and 88%, respectively, compared with 84% and 74% without an intraoperative fracture (p = 0.36). Furthermore, the survival-free of revision surgery rates for aseptic distal loosening at 5 and 10 years were 88% and 88%, respectively, compared with 93% and 87% without a fracture (p = 0.85). Intraoperative fractures occur in approximately 2% of TWAs. These fractures do not appear to affect long-term implant survival or risk of fracture. Patient age and the need for bone graft were the only factors in the risk of intraoperative fractures. Postoperative fractures also occur in 2% of TWAs, but often result in revision surgery. Level III, therapeutic study.

35. Photographic copy of Hangar Door Canopy Details (Ammann and ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

35. Photographic copy of Hangar Door Canopy Details (Ammann and Whitney and The Ballinger Company. April 12, 1955). In files of the City of Philadelphia, Division of Aviation, Terminal E. Philadelphia International Airport. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

32. Photographic copy of Hangar Roof Framing Plan (Ammann and ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

32. Photographic copy of Hangar Roof Framing Plan (Ammann and Whitney and The Ballinger Company, April 12, 1955). In files of the City of Philadelphia, Division of Aviation, Terminal E, Philadelphia International Airport. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

27. Photographic copy of Mezzanine Plan, Roof Plan and Details ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

27. Photographic copy of Mezzanine Plan, Roof Plan and Details (The Ballinger Company, April 12, 1955). In files of the City of Philadelphia, Division of Aviation, Terminal E, Philadelphia International Airport. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

29. Photographic copy of West Elevation and Sections Through Building ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

29. Photographic copy of West Elevation and Sections Through Building (The Ballinger Company, April 12, 1955). In files of the City of Philadelphia. Division of Aviation. Terminal E. Philadelphia International Airport. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

Teachers' Autonomy in Today's Educational Climate: Current Perceptions from an Acceptable Instrument

ERIC Educational Resources Information Center

Strong, Luman E. G.; Yoshida, Roland K.

2014-01-01

This research evaluated the psychometric properties of Friedman's (1999) Teacher Work-Autonomy Scale (TWA) to determine whether it was an acceptable instrument to measure U.S. teacher autonomy in the present educational context. A second purpose was to ascertain the current status of teachers' perceptions of their autonomy from a sample of U.S.…

49 CFR 227.115 - Hearing protectors.

Code of Federal Regulations, 2011 CFR

2011-10-01

... employees exposed to sound levels that meet or exceed the action level. (c) Required use at action level. A railroad shall require the use of hearing protectors when an employee is exposed to sound levels that meet... hearing protectors when an employee is exposed to sound levels equivalent to an 8-hour TWA of 90 dB(A) or...

34. Photographic copy of Hangar Doors (Ammann and Whitney and ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

34. Photographic copy of Hangar Doors (Ammann and Whitney and The Ballinger Company, April 12, 1955). In files of the City of Philadelphia, Division of Aviaiton, Terminal E, Philadelphia International Airport. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

33. Photographic copy of Main Roof Girder Details (Ammann and ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

33. Photographic copy of Main Roof Girder Details (Ammann and Whitney and The Ballinger Company, April 12, 1955). In files of the City of Philadelphia, Division of Aviation, Terminal E, Philadelphia International Airport. Reprinted with permission of the Division of Aviaiton. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

INTERNATIONAL UNION OF OPERATING ENGINEERS NATIONAL HAZMAT PROGRAM - PORTER-CABLE CIRCULAR SAW OENHP: 2001-04, VERSION A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Unknown

2002-01-15

Florida International University's (FIU) Hemispheric Center for Environmental Technology (HCET) evaluated five saws for their effectiveness in cutting specially prepared fiberglass-reinforced plywood crates. These crates were built as surrogates for crates that presently hold radioactively contaminated glove boxes at the Department of Energy's (DOE) Los Alamos facility. The Porter-Cable circular saw was assessed on August 15-16, 2001 (Porter-Cable No.1 and Porter-Cable No.2, respectively). During the FIU test of efficacy, a team from the Operating Engineers National Hazmat Program (OENHP) evaluated the occupational safety and health issues associated with this technology. The Porter-Cable saw is a straightforward machine for cutting woodmore » of varying thickness. The blade is fully guarded with a fixed upper and a lower retractable guard. The lower guard retracts as the blade engages the work piece. The unit is operated with an on/off guarded trigger switch and is supported with a handgrip mounted near the front of the saw. The saw is equipped with a directional nozzle, which aims sawdust away from the operator and the line of cut. An optional vacuum system, attached to the directional nozzle, is used to remove and collect dust. During the demonstration of Porter-Cable No.1, personal noise sampling indicated that one worker was under and one was at the Occupational Safety and Health Administration's (OSHA) Action Level of 85 decibels (dBA) with time-weighted averages (TWA's) of 82.7 and 84.6 dBA, respectively. During the demonstration of Porter-Cable No.2, however, both workers did exceed the Action Level with TWA's of 89.7 and 90.0 dBA. These data are not entirely representative as they were gathered during a simulation and not at the actual worksite. Additional sampling should be conducted on-site, but the workers should wear hearing protection until it is determined that it is no longer necessary. The total nuisance dust sample for Porter-Cable No.1 was 3.53 milligrams per cubic meter (mg/m{sup 3}), which is lower than the OSHA Permissible Exposure Limit (PEL) of 15 mg/m{sup 3} and the American Conference of Governmental Industrial Hygienists' (ACGIH) Threshold Limit Value (TLV) of 10 mg/m{sup 3}. Porter-Cable No.2's nuisance dust results yielded a value of 22.05 mg/m{sup 3}, which is over the PEL and TLV. The fiber analysis for the first demonstration yielded 12.9 fibers per cubic centimeter (f/cc), which is much higher than the PEL of 1 f/cc. Galson Laboratories considered the fiber analysis for the second demonstration void due to the overloading of dust on the filter. Kickback, the sudden reaction to a pinched blade, is possible with this saw and could cause the saw to lift up and out of the work piece and toward the operator. Proper work position and firm control of the saw minimizes the potential for a sprain or strain. Care needs to be exercised to support the work piece properly and to not force the tool.« less

Chapter 8 Tool for monitoring hydrophilic contaminants in water: polar organic chemical integrative sampler (POCIS)

USGS Publications Warehouse

Alvarez, David A.; Huckins, James N.; Petty, Jimmie D.; Jones-Lepp, Tammy L.; Stuer-Lauridsen, Frank; Getting, Dominic T.; Goddard, Jon P.; Gravell, Anthony

2007-01-01

The development of the polar organic chemical integrative sampler (POCIS) provides environmental scientists and policy makers a tool for assessing the presence and potential impacts of the hydrophilic component of these organic contaminants. The POCIS provides a means for determining the time-weighted average (TWA) concentrations of targeted chemicals that can be used in risk assessments to determine the biological impact of hydrophilic organic compounds (HpOCs) on the health of the impacted ecosystem. Field studies have shown that the POCIS has advantages over traditional sampling methods in sequestering and concentrating ultra-trace to trace levels of chemicals over time resulting in increased method sensitivity, ability to detect chemicals with a relatively short residence time or variable concentrations in the water, and simplicity in use. POCIS extracts can be tested using bioassays and can be used in organism dosing experiments for determining toxicological significance of the complex mixture of chemicals sampled. The POCIS has been successfully used worldwide under various field conditions ranging from stagnant ponds to shallow creeks to major river systems in both fresh and brackish water.

Passive sampling of bioavailable organic chemicals in Perry County, Missouri cave streams.

PubMed

Fox, J Tyler; Adams, Ginny; Sharum, Martin; Steelman, Karen L

2010-12-01

Two types of passive samplers--semipermeable membrane devices (SPMDs) and polar organic chemical integrative samplers (POCIS)--were deployed in spring 2008 to assess bioavailable concentrations of aquatic contaminants in five cave streams and resurgences in Perry County, Missouri. Study sites represent areas of high cave biodiversity and the only known habitat for grotto sculpin (Cottus carolinae). Time-weighted average (TWA) water concentrations were calculated for 20 compounds (n = 9 SPMDs; n = 11 POCIS) originating primarily from agricultural sources, including two organochlorine insecticides, dieldrin and heptachlor epoxide, which were found at levels exceeding U.S. EPA criteria for the protection of aquatic life. GIS data were used to quantify and map sinkhole distribution and density within the study area. Infiltration of storm runoff and its influence on contaminant transport were also evaluated using land cover and hydrological data. This work provides evidence of cave stream contamination by a mix of organic chemicals and demonstrates the applicability of passive samplers for monitoring water quality in dynamic karst environments where rapid transmission of storm runoff makes instantaneous water sampling difficult.

31. Photographic copy of Leanto Roof Framing Plan & Bent ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

31. Photographic copy of Leanto Roof Framing Plan & Bent Details (Ammann and Whitney and The Balinger Company, April 12, 1955). In files of the City of Philadelphia, Division of Aviation, Terminal E, Philadelphia International Airport. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

19. Photographic copy of photograph of portion of east elevation ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. Photographic copy of photograph of portion of east elevation taken on March 22, 1957 showing door beam and ladder to building roof. Photographer unknown. Original photograph property of the City of Philadelphia. Division of Aviation. Reprinted with permission of the Division of Aviation. - TWA Maintenance Hangar, South side of Tinicum Island Road, Philadelphia International Airport, Philadelphia, Philadelphia County, PA

30 CFR 62.101 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 85 dBA, or equivalently a dose of 50%, integrating all sound levels from 80 dBA to at least 130 dBA... Protection Level. A TWA8 of 105 dBA, or equivalently, a dose of 800% of that permitted by the standard, integrating all sound levels from 90 dBA to at least 140 dBA. Exchange rate. The amount of increase in sound...

30 CFR 62.101 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 85 dBA, or equivalently a dose of 50%, integrating all sound levels from 80 dBA to at least 130 dBA... Protection Level. A TWA8 of 105 dBA, or equivalently, a dose of 800% of that permitted by the standard, integrating all sound levels from 90 dBA to at least 140 dBA. Exchange rate. The amount of increase in sound...

Workplace Support, Discrimination, and Person-Organization Fit: Tests of the Theory of Work Adjustment with LGB Individuals

ERIC Educational Resources Information Center

Velez, Brandon L.; Moradi, Bonnie

2012-01-01

The present study explored the links of 2 workplace contextual variables--perceptions of workplace heterosexist discrimination and lesbian, gay, and bisexual (LGB)-supportive climates--with job satisfaction and turnover intentions in a sample of LGB employees. An extension of the theory of work adjustment (TWA) was used as the conceptual framework…

M Stars in the TW Hydra Association: A Chandra Large Program Survey

NASA Astrophysics Data System (ADS)

Punzi, Kristina; Kastner, Joel; Principe, David; Stelzer, Beate; Gorti, Uma; Pascucci, Illaria; Argiroffi, Costanza

2018-01-01

We have conducted a Cycle 18 Chandra Large Program survey of very cool members of the $\\sim$ 8 Myr-old TW Hydra Association (TWA) to extend our previous study of the potential connections between M star disks and X-rays (Kastner et al. 2016, AJ, 152, 3) to the extreme low-mass end of the stellar initial mass function. The spectral types of our targets extend down to the M/L borderline. Thus we can further investigate the potential connection between the intense X-ray emission from young, low-mass stars and the lifetimes of their circumstellar planet-forming discs, as well as better constrain the age at which coronal activity declines for stellar masses approaching the H-burning limit of $\\sim$ 0.08 M$_{\\odot}$. We present preliminary results from the Cycle 18 survey, including X-ray detection statistics and measurements of relative X-ray luminosities and coronal (X-ray) temperatures for those TWA stars detected by Chandra. This research is supported by SAO/CXC grant GO7-18002A and NASA Astrophysics Data Analysis program grants NNX12AH37G and NNX16AG13G to RIT.

TWA Flight 800, explosion airblast unexplained

NASA Astrophysics Data System (ADS)

Reed, Jack W.

2003-10-01

TWA Flight 800 disintegrated off Long Island, NY, on 16 July 1996. Immediate reports from other flyers described what appeared as attacking missiles. Search for terrorists began quickly, with over 1000 FBI agents to collect debris, interview eyewitnesses, and analyze sightings to give a missile launch point. They found no evidence of criminal attack, and turned investigations over to the NTSB to find some accidental cause. The ``empty'' central fuel tank was determined to be the likely explosion source. On the other hand, early witnesses reported a ``loud'' bang after seeing a great fireball fall from the sky, but at 15 km or greater range, they saw and heard two different events. This acoustic discrepancy has not been adequately investigated. When finally released, FBI reports from more than 200 ``ear-witnesses'' give similar observations. Their loudness reports confirm that at least a ton of TNT equivalent explosion had occurred. NASA acousticians engaged by NTSB, however, through spectral analysis techniques for sonic booms, concluded that a 10-kg TNT explosion, from detonating fuel tank vapors, could be heard on Long Island. Evidence for a much larger yield is presented here, but its form remains a mystery.

A dolphin lower jaw is a hydroacoustic antenna of the traveling wave

NASA Astrophysics Data System (ADS)

Ryabov, Vyacheslav A.

2003-10-01

The purpose of the work is the analysis of a possible function of mental foramens as channels through which the echo passes in the lower jaw fat body and the determination of a role of channels and a skull in formation of the directivity of the dolphin echolocation hearing. Concrete problems were studying of the lower jaw morphology, modeling and calculation of a dolphin, tursiops truncatus p., echolocation hearing beam pattern. The outcomes of the work indicate those morphological structures of the lower jaw; the left and right half represents two hydroacoustic receiving antennas of the traveling wave type, TWA farther. The mental foramens of a dolphin lower jaw represent nonequidistant array of waveguide delay lines, and determine the phase and amplitude distribution of each of the antenna's array. The beam pattern of the echolocation hearing was calculated with the usage of the TWA model, and the allowance of flat sound wave diffraction. The beam pattern shape is naturally determined by the echolocation hearing functionality. It is equally well adapted both for echolocation and for pulses echo detection. A steepness of the bearing characteristic is estimated; it reaches 0.7 dB per degree.

Understanding the dark and bright sides of anxiety: A theory of workplace anxiety.

PubMed

Cheng, Bonnie Hayden; McCarthy, Julie M

2018-05-01

Researchers have uncovered inconsistent relations between anxiety and performance. Although the prominent view is a "dark side," where anxiety has a negative relation with performance, a "bright side" of anxiety has also been suggested. We reconcile past findings by presenting a comprehensive multilevel, multiprocess model of workplace anxiety called the theory of workplace anxiety (TWA). This model highlights the processes and conditions through which workplace anxiety may lead to debilitative and facilitative job performance and includes 19 theoretical propositions. Drawing on past theories of anxiety, resource depletion, cognitive-motivational processing, and performance, we uncover the debilitative and facilitative nature of dispositional and situational workplace anxiety by positioning emotional exhaustion, self-regulatory processing, and cognitive interference as distinct contrasting processes underlying the relationship between workplace anxiety and job performance. Extending our theoretical model, we pinpoint motivation, ability, and emotional intelligence as critical conditions that shape when workplace anxiety will debilitate and facilitate job performance. We also identify the unique employee, job, and situational characteristics that serve as antecedents of dispositional and situational workplace anxiety. The TWA offers a nuanced perspective on workplace anxiety and serves as a foundation for future work. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Detection and Prevention of Arrhythmias During Space Flight

NASA Technical Reports Server (NTRS)

Pillai, Dilip; Rosenbaum, David; Liszka, Kathy; York, David; Mackin, Michael; Lichter, Michael

2004-01-01

Objectives of this research include:determine if orthogonal lead sets can; determine if orthogonal lead sets can correct artifactual ECG changes caused by correct artifactual ECG changes caused by microgravity- induced alterations in cardiac position; determine if markers of susceptibility to SCD (TWA and QT restitution) can be reliably measured during space flight; determine the effects of continuous microgravity on markers of susceptibility to SCD.

Changes in hydro-meteorological conditions over tropical West Africa (1980-2015) and links to global climate

NASA Astrophysics Data System (ADS)

Ndehedehe, Christopher E.; Awange, Joseph L.; Agutu, Nathan O.; Okwuashi, Onuwa

2018-03-01

The role of global sea surface temperature (SST) anomalies in modulating rainfall in the African region has been widely studied and is now less debated. However, their impacts and links to terrestrial water storage (TWS) in general, have not been studied. This study presents the pioneer results of canonical correlation analysis (CCA) of TWS derived from both global reanalysis data (1980-2015) and GRACE (Gravity Recovery and Climate Experiment) (2002-2014) with SST fields. The main issues discussed include, (i) oceanic hot spots that impact on TWS over tropical West Africa (TWA) based on CCA, (ii) long term changes in model and global reanalysis data (soil moisture, TWS, and groundwater) and the influence of climate variability on these hydrological indicators, and (iii) the hydrological characteristics of the Equatorial region of Africa (i.e., the Congo basin) based on GRACE-derived TWS, river discharge, and precipitation. Results of the CCA diagnostics show that El-Niño Southern Oscillation related equatorial Pacific SST fluctuations is a major index of climate variability identified in the main portion of the CCA procedure that indicates a significant association with long term TWS reanalysis data over TWA (r = 0.50, ρ < 0.05). Based on Mann-Kendall's statistics, the study found fairly large long term declines (ρ < 0.05) in TWS and soil moisture (1982 - 2015), mostly over the Congo basin, which coincided with warming of the land surface and the surrounding oceans. Meanwhile, some parts of the Sahel show significant wetting (rainfall, soil moisture, groundwater, and TWS) trends during the same period (1982-2015) and aligns with the ongoing narratives of rainfall recovery in the region. Results of singular spectral analysis and regression confirm that multi-annual changes in the Congo River discharge explained a considerable proportion of variability in GRACE-hydrological signal over the Congo basin (r = 0.86 and R2 = 0.70, ρ < 0.05). Finally, leading orthogonal modes of MERRA and GRACE-TWS over TWA show significant association with global SST anomalies.

Color discrimination impairment in workers exposed to mercury vapor.

PubMed

Urban, Pavel; Gobba, Fabriziomaria; Nerudová, Jana; Lukás, Edgar; Cábelková, Zdena; Cikrt, Miroslav

2003-08-01

To study color discrimination impairment in workers exposed to elemental mercury (Hg) vapor. Twenty-four male workers from a chloralkali plant exposed to Hg vapor, aged 42+/-9.8 years, duration of exposure 14.7+/-9.7 years, were examined. The 8h TWA air-borne Hg concentration in workplace was 59 microg/m(3); mean Hg urinary excretion (HgU) was 20.5+/-19.3 microg/g creatinine; mean Hg urinary excretion after the administration of a chelating agent, sodium 2,3-dimercapto-1-propane-sulfonate (DMPS), was 751.9+/-648 microg/48h. Twenty-four age- and gender-matched control subjects were compared. Visual acuity, alcohol intake, smoking habits, and history of diseases or drugs potentially influencing color vision were registered. The Lanthony 15-Hue desaturated test (L-D15-d) was used to assess color vision. The results were expressed quantitatively as Bowman's Color Confusion Index (CCI), and qualitatively according to Verriest's classification of acquired dyschromatopsias. The CCI was significantly higher in the exposed group than in the control (mean CCI 1.15 versus 1.04; P=0.04). The proportion of subjects with errorless performance on the Lanthony test was significantly lower in the Hg exposed group compared to referents (52% versus 73%; P=0.035). The exposed group showed higher frequency of type III dyschromatopsias (blue-yellow confusion axis) in comparison with the control group (12.5% versus 8.3%), however, the difference did not reach statistical significance. Multiple regression did not show any significant relationship between the CCI, and age, alcohol consumption, or measures of exposure. In agreement with previous studies by Cavalleri et al. [Toxicol. Lett. 77 (1995) 351; Environ. Res. Sec. A 77 (1998) 173], the results of this study support the hypothesis that exposure to mercury vapor can induce sub-clinical color vision impairment. This effect was observed at an exposure level below the current biological limit for occupational exposure to mercury. This raises doubts on the actual protection afforded by this limit concerning the effect of mercury on color vision.

Post-Kemron, Uganda demands proof of the "Mariandina" drug.

PubMed

1996-12-01

An ethical review committee consisting of medical scientists, social scientists, and lawyers has been established by the Ugandan government to oversee individuals and institutions conducting biomedical research. The research of Professor Sali, who produced and marketed Mariandina as a cure for acquired immunodeficiency syndrome (AIDS), is not recognized, according to Dr. Jeremiah Twa-twa, Registrar of the National Medical Council. Professor Sali had been given six months to produce an acceptable protocol, with controls, that demonstrated the efficacy of the drug. He had stated previously that his patients received a minimum of six tablets daily of Mariandina A, B, or J; thousands are said to have been treated. Professor Sali, who returned to Uganda in 1990 with a 100,000-pound loan to produce the drug, advised his patients to sell everything they owned in order to pay for their treatment, according to Major Ruranga Rubaramira (head of a joint clinical council). The Uganda AIDS Commission is also considering the use of herbs in the treatment of AIDS; nine Western-trained researchers are collaborating with herbalists in studies that have shown promising results. Dr. Donna Kabatesi, who heads a clinic that uses both herbs and Western medicine in the treatment of AIDS patients at Mulago hospital, believes herbs are equally effective for some purposes.

Thiolated polymers: evaluation of their potential as dermoadhesive excipients.

PubMed

Grießinger, Julia Anita; Bonengel, Sonja; Partenhauser, Alexandra; Ijaz, Muhammad; Bernkop-Schnürch, Andreas

2017-02-01

The objective of this study was to evaluate and compare four different thiolated polymers regarding their dermoadhesive potential. Therefore, three hydrophilic polymers (poly(acrylic acid), Carbopol 971 and carboxymethylcellulose) and a lipophilic polymer (silicone oil) were chosen to generate thiolated polymers followed by characterization. The total work of adhesion (TWA) and the maximum detachment force (MDF) of formulations containing modified and unmodified polymers were investigated on skin obtained from pig ears using a tensile sandwich technique. The synthesis of thiolated polymers provided 564 µmol, 1079 µmol, 482 µmol and 217 µmol thiol groups per gram poly(acrylic acid), Carbopol 971, carboxymethylcellulose and silicone oil, respectively. Hydrogels containing poly(acrylic acid)-cysteine, Carbopol 971-cysteine, and carboxymethylcellulose-cysteamine exhibited a 6-fold, 25-fold and 9-fold prolonged adhesion on porcine skin than the hydrogel formulations prepared from the corresponding unmodified polymers, respectively. Furthermore, thiolation of silicone oil with thioglycolic acid led to a 5-fold improvement in adhesion compared to the unmodified silicone oil. A comparison between the four thiolated polymer formulations showed a clear correlation between the amount of coupled thiol groups and the TWA. According to these results thiomers might also be useful excipients to provide a prolonged dermal resistance time of various formulations.

Thermally Tunable Ultra-wideband Metamaterial Absorbers based on Three-dimensional Water-substrate construction.

PubMed

Shen, Yang; Zhang, Jieqiu; Pang, Yongqiang; Zheng, Lin; Wang, Jiafu; Ma, Hua; Qu, Shaobo

2018-03-13

Distilled water has frequency dispersive characteristic and high value of imaginary part in permittivity, which can be seen as a good candidate of broadband metamaterial absorbers(MAs) in microwave. Here, an interesting idea based on the combination of water-substrate and metallic metamaterial in the three-dimensional construction is proposed, which can achieve outstanding broadband absorption. As a proof, the distilled water is filled into the dielectric reservoir as ultra-thin water-substrate, and then the water-substrates are arranged on the metal backplane periodically as three-dimensional water-substrate array(TWA). Simulation shows that the TWA achieves broadband absorption with the efficiency more than 90% from 8.3 to 21.0 GHz. Then, the trigonal metallic fishbone structure is introduced here between the water-substrate and the dielectric reservoir periodically as three-dimensional water-substrate metamaterial absorber(TWMA). The proposed TWMA could achieve ultra-broadband absorption from 2.6 to 16.8 GHz, which has increase by 64.8% in relative absorption bandwidth. Meanwhile, due to the participation of distilled water, the thermally tunable property also deserves to be discussed here. In view of the outstanding performance, it is worth to expect a wide range of applications to emerge inspired from the proposed construction.

A Combustion Model for the TWA 800 Center-Wing Fuel Tank Explosion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baer, M.R.; Gross, R.J.

1998-10-02

In support of the National Transportation Safety Board investigation of the TWA Flight 800 accident, a combined experimental/computational effort was conducted that focused on quarter-scale testing and simulation of the fuel-air explosion in the Boeing 747 center wing fuel tank. This report summarizes the modeling approach used at Sandia National Laboratories. In this approach approximations are introduced that capture the essential physics associated with turbulent flame propagation in multiple compartment fuel tanks. This model efficiently defines the pressure loading conditions during a jet-fuel air explosion in a fuel tank confinement. Modeling calculations compare favorably with a variety of experimental quarter-scalemore » tests conducted in rigid confinement. The modeling describes well the overpressure history in several geometry configurations. Upon demonstrating a reasonable comparison to experimental observations, a parametric study of eight possible ignition sources is then discussed. Model calculations demonstrate that different loading conditions arise as the location of the ignition event is varied. By comparing the inferred damage and calculated impulses to that seen in the recovered tank, it maybe possible to reduce the number of likely sources. A possible extension of this work to better define tank damage includes coupling the combustion model as a pressure loading routine for structural failure analysis.« less

Measurement systems and indices of miners' exposure to radon daughter products in the air of mines.

PubMed

Domański, T

1990-01-01

This paper presents the classification of measurement systems that may be used for the assessment of miners' exposure to radiation in mines. The following systems were described and characterized as the Air Sampling System (ASS), the Environmental Control System (ECS), the Individual Dosimetry System (IDS), the Stream Monitoring System (SMS) and the Exhaust Monitoring System (EMS). The indices for evaluation of miners' working environments, or for assessment of individual or collective miners' exposure, were selected and determined. These are: average expected concentration (CAE), average observed concentration (CAO), average expected rate of exposure cumulation rate (EEXP), average observed exposure cumulation rate (EOBS), average effective exposure cumulation rate (EEFF). Mathematical formulae for determining all these indicators, according to the type of measurement system used in particular mines, are presented. The reliability of assessment of miners' exposure in particular measurement systems, as well as the role of the possible reference system, are discussed.

A study of circumstellar disk properties in low-mass stars and brown dwarfs

NASA Astrophysics Data System (ADS)

Riaz, Basmah

We present Spitzer Space Telescope IRAC and MIPS observations for a sample of eight M dwarfs: six dMe, one dM, and one sdMe star. All of our targets are found to have Spectral Energy Distributions (SEDs) which are fitted within the error bars by a purely photospheric spectrum out to 24m m . The estimated ages for all are >10 Myr, suggesting that enough disk dissipation has occurred within the inner several AU of the star. Scaling from Houdebine's model of the AU Mic chromosphere, we have computed the free-free infrared excesses for a range of densities. Our Spitzer 24m m data shows that the chromospheres in two of our targets are less dense than in AU Mic by a factor of 10 or more. Our models also indicate that the chromospheric contribution to the observed AU Mic emission at submillimeter wavelengths is only about 2%. We present Spitzer IRAC, MIPS and IRS observations for three sub-stellar members of the TW Hydrae Association (TWA): 2MASSW J1207334-393254 (2M1207), SSSPM J1102-3431 (SSSPM 1102), and 2MASS J1139511-315921 (2M1139). The near- to mid-infrared SEDs indicate the presence of flat optically thick disks around 2M1207 and SSSPM 1102, and a transition disk around 2M1139. 2M1207 shows absorption in the 10 m m silicate feature, with a peak near 11.3 m m due to crystalline forsterite. The absorption can be attributed to a close to edge-on disk. No silicate absorption/emission is observed towards SSSPM 1102. We have performed detailed modeling of these two brown dwarf disks. The best-fits have been obtained using a flat disk of mass 10 -4 [Special characters omitted.] , M of 10 -10 [Special characters omitted.] /yr, and an inclination angle of 75=B0 for 2M1207, whereas a disk mass of 10 -5 [Special characters omitted.] , M of 10 -11 [Special characters omitted.] /yr, and an inclination angle of 63° provides a good fit to SSSPM 1102. Modeling of the 10 m m silicate feature requires the presence of large (>50 m m ) grains in the disk midplane, which indicates substantial grain growth and dust settling in both brown dwarf disks. Our analysis of the stellar and sub-stellar members of the TWA indicates that while only 6 out of 25 stellar members show excess emission at these mid- infrared wavelengths, all of the TWA brown dwarfs that have been observed so far with Spitzer show signs of disks around them, resulting in a disk fraction of at least 60%. A comparison with younger clusters indicates that by the age of the TWA (~10 Myr), the disk fraction for brown dwarfs has not decreased, whereas it drops by a factor of ~2 for the higher mass stars. This suggests longer disk decay time scales for brown dwarfs compared to higher mass stars.

Ototoxicity in rats exposed to ethylbenzene and to two technical xylene vapours for 13 weeks.

PubMed

Gagnaire, François; Langlais, Cristina; Grossmann, Stéphane; Wild, Pascal

2007-02-01

Male Sprague-Dawley rats were exposed to ethylbenzene (200, 400, 600 and 800 ppm) and to two mixed xylenes (250, 500, 1,000 and 2,000 ppm total compounds) by inhalation, 6 h/day, 6 days/week for 13 weeks and sacrificed for morphological investigation 8 weeks after the end of exposure. Brainstem auditory-evoked responses were used to determine auditory thresholds at different frequencies. Ethylbenzene produced moderate to severe ototoxicity in rats exposed to the four concentrations studied. Increased thresholds were observed at 2, 4, 8 and 16 kHz in rats exposed to 400, 600 and 800 ppm ethylbenzene. Moderate to severe losses of outer hair cells of the organ of Corti occurred in animals exposed to the four concentrations studied. Exposure to both mixed xylenes produced ototoxicity characterized by increased auditory thresholds and losses of outer hair cells. Ototoxicity potentiation caused by ethylbenzene was observed. Depending on the mixed xylene studied and the area of the concentration-response curves taken into account, the concentrations of ethylbenzene in mixed xylenes necessary to cause a given ototoxicity were 1.7-2.8 times less than those of pure ethylbenzene. Given the high ototoxicity of ethylbenzene, the safety margin of less or equal to two (LOAEL/TWA) might be too small to protect workers from the potential risk of ototoxicity. Moreover, the enhanced ototoxicity of ethylbenzene and para-xylene observed in mixed xylenes should encourage the production of mixed xylenes with the lowest possible concentrations of ethylbenzene and para-xylene.

Exposure-response relationships of occupational inhalative allergens.

PubMed

Baur, X; Chen, Z; Liebers, V

1998-05-01

Only a few threshold limit values exist at present for allergens in the workplace known to cause bronchial asthma. This contrasts with the great number of occupational asthma cases observed in industrialized countries. Recently published studies provide clear evidence for exposure intensity response relationships of occupational allergens of plant, microbiological, animal or man-made origin. If allergen exposure levels fall short of determined limit values, they are not associated with an increased risk of occupational asthma. Corresponding data are available for wheat flour (1-2.4 mg/m3), fungal alpha-amylase (0.25 ng/m3), natural rubber latex (0.6 ng/m3), western red cedar (0.4 mg/m3) and rat allergens (0.7 microg/m3). It is suggested to stipulate legally binding threshold limit values (TLV/TWA) on this basis in order to induce more effective primary preventive measures. If no reliable data on the health risk of an occupational airborne noxa exist, the lowest reasonably practicable exposure level has to be achieved. Appropriate secondary preventive measures have to be initiated in all workplaces contaminated with airborne allergens. Verified exposure-response relationships provide the basis for risk assessment and for targeted interventions to reduce the incidence of occupational asthma also in consideration of cost benefit aspects. 'Occupational asthma is a disease characterized by variable airflow limitation and/or airway hyperresponsiveness due to causes in a working environment. These causes can give rise to asthma through immunological or non-immunological mechanisms. Up to 15% of all asthma cases are of occupational origin or have at least a significant causal occupational factor. According to the New Zealand part of the European Respiratory Health Survey, an increased risk of asthma prevalence was found for several occupations such as laboratory technicians, food producers, chemical workers, plastic and rubber workers. The Spain part of this study comprising 2646 Spanish subjects showed an asthma risk to be attributed to occupational exposures between 5 and 6.7%. Main asthma-inducing agents in the workplace are flour, grain and feed dust, animal dander/urinary proteins and isocyanates. Further, several inhalative irritants such as chlorine, acid or alkaline aerosols play a pivotal role. Many low molecular weight chemicals have irritative as well as allergenic effects on the airways, e. g. isocyanates and acid anhydrides. In addition to chronic or repetitive exposures, also singular accidental exposure to high concentrations of irritative or toxic airborne substances can cause occupational asthma. This condition is frequently called reactive airways dysfunction.

Taxonomic review of tropical western Atlantic shallow water Drilliidae (Mollusca: Gastropoda: Conoidea) including descriptions of 100 new species.

PubMed

Fallon, Phillip J Jr

2016-03-14

A review of the literature and examination of over 3,200 specimens of shallow water (<200 m) tropical western Atlantic (TWA) Drilliidae Olson, 1964 in museum and private collections has resulted in the recognition of numerous previously undescribed species, 100 of which are proposed here for the first time. A total of 65 names were found in the literature. Of these, 48 are considered valid, 16 synonyms, and one nomen dubium. In addition, characteristics that distinguish each genus currently in use for TWA shallow water species have indicated the need for reassignment (new combinations within Drilliidae) of 15 species. Some nomenclatural actions have come about from the literature review and include one taxon placed in junior synonymy (under an older name recently re-discovered) and one new name for a junior homonym. Two neotypes, five lectotype designations, and one new name are also proposed. Altogether, nomenclatural actions on 17% of valid previously described taxa are proposed. The 100 proposed names are placed in 12 available and one new genus: Agladrillia Woodring, 1928 (2), Bellaspira Conrad, 1868 (7), Calliclava McLean, 1971 (3), Cerodrillia Bartsch & Rehder, 1939 (11), Clathrodrillia Dall, 1918 (6), Decoradrillia, new genus (4), Douglassia Bartsch, 1934 (4), Fenimorea Bartsch, 1934 (15), Leptadrillia Woodring, 1928 (12), Lissodrillia Bartsch & Rehder, 1939 (8), Neodrillia Bartsch, 1943 (2), Splendrillia Hedley, 1922 (13), and Syntomodrillia Woodring, 1928 (13). These are the first reports of Calliclava in the western Atlantic, previously known only from the eastern Pacific. The new genus, Decoradrillia, is proposed to hold four new species and one existing that share a unique shell microsculpture and other morphological traits. One genus, Drillia Gray, 1838, is not currently believed to have TWA representatives. Three genera comprised exclusively of bathyal species are not treated in this work: Clavus Monfort, 1810 (=Eldridgea Bartsch, 1934), Globidrillia Woodring, 1928, and Spirotropis Sars, 1878. The significant increase in species within all of the genera has the effect of strengthening the groups' diagnostic characters by their presence across a greater number of species. Each of the 148 valid species treated herein are described (or redescribed) and photographs of types presented, as are photographs of morphological variants and representatives from separate geographic areas, if available, to illustrate species' variability.

USAF Dental Service Mercury Hygiene Report, Calendar Year 1980.

DTIC Science & Technology

1981-12-01

the floor. Mercury Vapor Analyzer Used No. calibration No. of clinics Percent reported MV2 - Bacharach 81 67.5 14 Hopcalite tubes 8 6.7 Jerome model...instruments which could determine TWA: hopcalite tubes (8), Jerome with dosimeter coils (5), and 3M monitor (3). All 16 of these surveys showed mercury...vapor levels. This quantification requires sampling using the Jerome with a dosimeter coil, hopcalite tubes, or the 3M monitor. The USAF Occupational

Immunological monitoring of dry-cleaning shop workers--exposure to tetrachloroethylene.

PubMed

Andrýs, C; Hanovcová, I; Chýlková, V; Tejral, J; Eminger, S; Procházková, J

1997-09-01

A panel of immunological parameters has been examined in a group of dry-cleaning workers (n = 21) and in a control group of administrators (n = 16) from the same plant. The results were also compared to long-term laboratory reference values (LRV) (n = 14-311). External exposure to tetrachloroethylene (PER) was represented by TWA (8 h) values in the range 11-752 mg PER/m3. Biological monitoring showed an amount from 9 to 344 mg PER/m3 in exhaled air by the end of workshift. 1. The exposed dry-cleaning workers compared to the controls from the plant had statistically significant changes in metabolic activity of phagocytes, alpha 2-macroglobulin, C3 and C4 complement component, salivary secretory IgA, and blastic transformation test. Most of the values were within the range of normal values. 2. The exposed dry-cleaning workers had several abnormal immune parameters compared to the long-term laboratory values (LRV) especially in the alpha 2-macroglobulin, C3 and percentage of T-lymphocytes. Most of the changes, even those that were statistically significant, were still within the range of normal values, but they might be classified as trends or shifts away from normal (spontaneous blastic transformation, absolute number of phagocyting cells, coeruloplasmin, circulating immunocomplexes, serum lysozyme). 3. The non-exposed controls from the same plant showed both quantitative and qualitative differences when compared to the LRV. Changes were seen in IgG, C4, CSI and in increased spontaneous metabolic activity of leucocytes, total leucocyte count, absolute number of phagocyting cells, alpha 2-macroglobulin, prealbumin, C4, circulating immunocomplexes and serum lysozyme. 4. The distribution analysis of all results detected a large number of abnormal values in both groups, more in the at-risk group. 5. As inhalation was the main route of PER exposure it was concluded that the changes might represent aspects of the response of the respiratory immune system, mainly of the alveolar macrophages. Additional postinfection effects could not be excluded in both studied groups. Individual differences in immune reactivity as well as individual range of exposure should be taken into consideration.

An estimation of Canadian population exposure to cosmic rays.

PubMed

Chen, Jing; Timmins, Rachel; Verdecchia, Kyle; Sato, Tatsuhiko

2009-08-01

The worldwide average exposure to cosmic rays contributes to about 16% of the annual effective dose from natural radiation sources. At ground level, doses from cosmic ray exposure depend strongly on altitude, and weakly on geographical location and solar activity. With the analytical model PARMA developed by the Japan Atomic Energy Agency, annual effective doses due to cosmic ray exposure at ground level were calculated for more than 1,500 communities across Canada which cover more than 85% of the Canadian population. The annual effective doses from cosmic ray exposure in the year 2000 during solar maximum ranged from 0.27 to 0.72 mSv with the population-weighted national average of 0.30 mSv. For the year 2006 during solar minimum, the doses varied between 0.30 and 0.84 mSv, and the population-weighted national average was 0.33 mSv. Averaged over solar activity, the Canadian population-weighted average annual effective dose due to cosmic ray exposure at ground level is estimated to be 0.31 mSv.

Assessment of radio frequency exposures in schools, homes, and public places in Belgium.

PubMed

Verloock, Leen; Joseph, Wout; Goeminne, Francis; Martens, Luc; Verlaek, Mart; Constandt, Kim

2014-12-01

Characterization of exposure from emerging radio frequency (RF) technologies in areas where children are present is important. Exposure to RF electromagnetic fields (EMF) was assessed in three "sensitive" microenvironments; namely, schools, homes, and public places located in urban environments and compared to exposure in offices. In situ assessment was conducted by performing spatial broadband and accurate narrowband measurements, providing 6-min averaged electric-field strengths. A distinction between internal (transmitters that are located indoors) and external (outdoor sources from broadcasting and telecommunication) sources was made. Ninety-four percent of the broadband measurements were below 1 V m(-1). The average and maximal total electric-field values in schools, homes, and public places were 0.2 and 3.2 V m(-1) (WiFi), 0.1 and 1.1 V m(-1) (telecommunication), and 0.6 and 2.4 V m(-1) (telecommunication), respectively, while for offices, average and maximal exposure were 0.9 and 3.3 V m(-1) (telecommunication), satisfying the ICNIRP reference levels. In the schools considered, the highest maximal and average field values were due to internal signals (WiFi). In the homes, public places, and offices considered, the highest maximal and average field values originated from telecommunication signals. Lowest exposures were obtained in homes. Internal sources contributed on average more indoors (31.2%) than outdoors (2.3%), while the average contributions of external sources (broadcast and telecommunication sources) were higher outdoors (97.7%) than at indoor positions (68.8%). FM, GSM, and UMTS dominate the total downlink exposure in the outdoor measurements. In indoor measurements, FM, GSM, and WiFi dominate the total exposure. The average contribution of the emerging technology LTE was only 0.6%.

Development of retrospective quantitative and qualitative job-exposure matrices for exposures at a beryllium processing facility.

PubMed

Couch, James R; Petersen, Martin; Rice, Carol; Schubauer-Berigan, Mary K

2011-05-01

To construct a job-exposure matrix (JEM) for an Ohio beryllium processing facility between 1953 and 2006 and to evaluate temporal changes in airborne beryllium exposures. Quantitative area- and breathing-zone-based exposure measurements of airborne beryllium were made between 1953 and 2006 and used by plant personnel to estimate daily weighted average (DWA) exposure concentrations for sampled departments and operations. These DWA measurements were used to create a JEM with 18 exposure metrics, which was linked to the plant cohort consisting of 18,568 unique job, department and year combinations. The exposure metrics ranged from quantitative metrics (annual arithmetic/geometric average DWA exposures, maximum DWA and peak exposures) to descriptive qualitative metrics (chemical beryllium species and physical form) to qualitative assignment of exposure to other risk factors (yes/no). Twelve collapsed job titles with long-term consistent industrial hygiene samples were evaluated using regression analysis for time trends in DWA estimates. Annual arithmetic mean DWA estimates (overall plant-wide exposures including administration, non-production, and production estimates) for the data by decade ranged from a high of 1.39 μg/m(3) in the 1950s to a low of 0.33 μg/m(3) in the 2000s. Of the 12 jobs evaluated for temporal trend, the average arithmetic DWA mean was 2.46 μg/m(3) and the average geometric mean DWA was 1.53 μg/m(3). After the DWA calculations were log-transformed, 11 of the 12 had a statistically significant (p < 0.05) decrease in reported exposure over time. The constructed JEM successfully differentiated beryllium exposures across jobs and over time. This is the only quantitative JEM containing exposure estimates (average and peak) for the entire plant history.

Concentration Levels of Particulate Matter of Common Dental Lab Materials in a Military Dental Lab

DTIC Science & Technology

2016-05-01

to cause contact type dermatitis in some dental laboratory technicans. 22 In both experimental animals and humans, methyl methacrylate is rapidly...being measured out and mixed. As cases of generalized neuropathy, asthma and contact dermatitis have been documented in dental laboratory technicians... contact .45 The sampling for paraffin wax particulate in the current study resulted in a REL 8-TWA of 0.2056 mg/m 3 which is well below the 2 mg/m 3

Optimization of a triode-type cusp electron gun for a W-band gyro-TWA

NASA Astrophysics Data System (ADS)

Zhang, Liang; Donaldson, Craig R.; He, Wenlong

2018-04-01

A triode-type cusp electron gun was optimized through numerical simulations for a W-band gyrotron traveling wave amplifier. An additional electrode in front of the cathode could switch the electron beam on and off instantly when its electric potential is properly biased. An optimal electron beam of current 1.7 A and a velocity ratio (alpha) of 1.12 with an alpha spread of ˜10.7% was achieved when the triode gun was operated at 40 kV.

General Design Memorandum, Gulfport Harbor, Mississippi. Design Memorandum Number 1. Appendix C. Geotechnical Report.

DTIC Science & Technology

1989-06-01

52.0) FLOYD ! WRS i CLASUATOI OF MATEPRALS CW Box OR ILEVATON TSPM oECD arl$bw) ~ VFtY SAWUL O1ro tw~a. VOW~ -w of~ a b Ol RX.. ISO = &&M." swfiomd...0IEXICO e o , 4 100 ’A KV 4) 0004 .000 ’A’ A--~-- 4 3 PROPOSED ALTERNATIVE ALK *&EW, NOT AN EXISTING CHANNEL XX 6’ ’% XC 𔄀ON 000LAYOUJT OF BORDIGS 4 2

Study and Evaluation of Current and Future Aircraft Loaders

DTIC Science & Technology

1986-08-01

Tigers Airlines JFK Airport , NY 10 Feb 86 Boeing Military Airplane Co. Boeing Commercial Airplane Co. Seattle, WA 11 Feb 86 Korean Airlines LAX, CA 12...Nash Boeing Aircraft Co., Seattle, WA Mr. J. Nelson JFK Airport , NY Mr. P. O’Brien ASD/ENCA Wright-Patterson AFB, OH Mr. C. Outran HQ AFLC/DSTMA...Locations 15 Oct 85 TWA Freight Terminal Laimbert Int’l Airport , St. Louis, mO 22 Nov 85 Lockheed - Georgia Aircraft Co. Marietta, GA 13 Dec 85 Flying

T-wave alternans and beat-to-beat variability of repolarization: pathophysiological backgrounds and clinical relevance.

PubMed

Floré, Vincent; Willems, Rik

2012-12-01

In this review, we focus on temporal variability of cardiac repolarization. This phenomenon has been related to a higher risk for ventricular arrhythmia and is therefore interesting as a marker of sudden cardiac death risk. We review two non-invasive clinical techniques quantifying repolarization variability: T-wave alternans (TWA) and beat-to-beat variability of repolarization (BVR). We discuss their pathophysiological link with ventricular arrhythmia and the current clinical relevance of these techniques.

Average household exposure to newspaper coverage about the harmful effects of hormone therapy and population-based declines in hormone therapy use.

PubMed

Haas, Jennifer S; Miglioretti, Diana L; Geller, Berta; Buist, Diana S M; Nelson, David E; Kerlikowske, Karla; Carney, Patricia A; Dash, Sarah; Breslau, Erica S; Ballard-Barbash, Rachel

2007-01-01

The news media facilitated the rapid dissemination of the findings from the estrogen plus progestin therapy arm of the Women's Health Initiative (EPT-WHI). To examine the relationship between the potential exposure to newspaper coverage and subsequent hormone therapy (HT) use. DESIGN/POPULATION: Population-based cohort of women receiving mammography at 7 sites (327,144 postmenopausal women). The outcome was the monthly prevalence of self-reported HT use. Circulation data for local, regional, and national newspapers was used to create zip-code level measures of the estimated average household exposure to newspaper coverage that reported the harmful effects of HT in July 2002. Women had an average potential household exposure of 1.4 articles. There was substantial variation in the level of average household exposure to newspaper coverage; women from rural sites received less than women from urban sites. Use of HT declined for all average potential exposure groups after the publication of the EPT-WHI. HT prevalence among women who lived in areas where there was an average household exposure of at least 3 articles declined significantly more (45 to 27%) compared to women who lived in areas with <1 article (43 to 31%) during each of the subsequent 5 months (relative risks 0.86-0.92; p < .006 for all). Greater average household exposure to newspaper coverage about the harms associated with HT was associated with a large population-based decline in HT use. Further studies should examine whether media coverage directly influences the health behavior of individual women.

Risk of silicosis in a Colorado mining community.

PubMed

Kreiss, K; Zhen, B

1996-11-01

We investigated exposure-response relations for silicosis among 134 men over age 40 who had been identified in a previous community-based random sample study in a mining town. Thirty-two percent of the 100 dust-exposed subjects had radiologic profusions of small opacities of I/O or greater at a mean time since first silica exposure of 36.1 years. Of miners with cumulative silica exposures of 2 mg/m3-years or less, 20% had silicosis; of miners accumulating > 2 mg/m3 years, 63% had silicosis. Average silica exposure was also strongly associated with silicosis prevalence rates, with 13% silicotics among those with average exposure of 0.025-0.05 mg/m3, 34% among those with exposures of > 0.05-0.1 mg/m3, and 75% among those with average exposures > 0.1 mg/m3. Logistic regression models demonstrated that time since last silica exposure and either cumulative silica exposure or a combination of average silica exposure and duration of exposure predicted silicosis risk. Exposure-response relations were substantially higher using measured silica exposures than using estimated silica exposures based on measured dust exposures assuming a constant silica proportion of dust, consistent with less exposure misclassification. The risk of silicosis found in this study is higher than has been found in workforce studies having no follow-up of those leaving the mining industry and in studies without job title-specific silica measurements, but comparable to several recent studies of dust exposure-response relationships which suggest that a permissible exposure limit of 0.1 mg/m3 for silica does not protect against radiologic silicosis.

Cross-shift changes in FEV1 in relation to wood dust exposure: the implications of different exposure assessment methods

PubMed Central

Schlunssen, V; Sigsgaard, T; Schaumburg, I; Kromhout, H

2004-01-01

Background: Exposure-response analyses in occupational studies rely on the ability to distinguish workers with regard to exposures of interest. Aims: To evaluate different estimates of current average exposure in an exposure-response analysis on dust exposure and cross-shift decline in FEV1 among woodworkers. Methods: Personal dust samples (n = 2181) as well as data on lung function parameters were available for 1560 woodworkers from 54 furniture industries. The exposure to wood dust for each worker was calculated in eight different ways using individual measurements, group based exposure estimates, a weighted estimate of individual and group based exposure estimates, and predicted values from mixed models. Exposure-response relations on cross-shift changes in FEV1 and exposure estimates were explored. Results: A positive exposure-response relation between average dust exposure and cross-shift FEV1 was shown for non-smokers only and appeared to be most pronounced among pine workers. In general, the highest slope and standard error (SE) was revealed for grouping by a combination of task and factory size, the lowest slope and SE was revealed for estimates based on individual measurements, with the weighted estimate and the predicted values in between. Grouping by quintiles of average exposure for task and factory combinations revealed low slopes and high SE, despite a high contrast. Conclusion: For non-smokers, average dust exposure and cross-shift FEV1 were associated in an exposure dependent manner, especially among pine workers. This study confirms the consequences of using different exposure assessment strategies studying exposure-response relations. It is possible to optimise exposure assessment combining information from individual and group based exposure estimates, for instance by applying predicted values from mixed effects models. PMID:15377768

Demonstration of a 140-GHz 1-kW Confocal Gyro-Traveling-Wave Amplifier

PubMed Central

Joye, Colin D.; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.

2009-01-01

The theory, design, and experimental results of a wideband 140-GHz 1-kW pulsed gyro-traveling-wave amplifier (gyro-TWA) are presented. The gyro-TWA operates in the HE06 mode of an overmoded quasi-optical waveguide using a gyrating electron beam. The electromagnetic theory, interaction theory, design processes, and experimental procedures are described in detail. At 37.7 kV and a 2.7-A beam current, the experiment has produced over 820 W of peak power with a –3-dB bandwidth of 0.8 GHz and a linear gain of 34 dB at 34.7 kV. In addition, the amplifier produced a –3-dB bandwidth of over 1.5 GHz (1.1%) with a peak power of 570 W from a 38.5-kV 2.5-A electron beam. The electron beam is estimated to have a pitch factor of 0.55–0.6, a radius of 1.9 mm, and a calculated perpendicular momentum spread of approximately 9%. The gyro-amplifier was nominally operated at a pulselength of 2 μs but was tested to amplify pulses as short as 4 ns with no noticeable pulse broadening. Internal reflections in the amplifier were identified using these short pulses by time-domain reflectometry. The demonstrated performance of this amplifier shows that it can be applied to dynamic nuclear polarization and electron paramagnetic resonance spectroscopy. PMID:20054451

Tree climbing and human evolution

PubMed Central

Venkataraman, Vivek V.; Kraft, Thomas S.; Dominy, Nathaniel J.

2013-01-01

Paleoanthropologists have long argued—often contentiously—about the climbing abilities of early hominins and whether a foot adapted to terrestrial bipedalism constrained regular access to trees. However, some modern humans climb tall trees routinely in pursuit of honey, fruit, and game, often without the aid of tools or support systems. Mortality and morbidity associated with facultative arboreality is expected to favor behaviors and anatomies that facilitate safe and efficient climbing. Here we show that Twa hunter–gatherers use extraordinary ankle dorsiflexion (>45°) during climbing, similar to the degree observed in wild chimpanzees. Although we did not detect a skeletal signature of dorsiflexion in museum specimens of climbing hunter–gatherers from the Ituri forest, we did find that climbing by the Twa is associated with longer fibers in the gastrocnemius muscle relative to those of neighboring, nonclimbing agriculturalists. This result suggests that a more excursive calf muscle facilitates climbing with a bipedally adapted ankle and foot by positioning the climber closer to the tree, and it might be among the mechanisms that allow hunter–gatherers to access the canopy safely. Given that we did not find a skeletal correlate for this observed behavior, our results imply that derived aspects of the hominin ankle associated with bipedalism remain compatible with vertical climbing and arboreal resource acquisition. Our findings challenge the persistent arboreal–terrestrial dichotomy that has informed behavioral reconstructions of fossil hominins and highlight the value of using modern humans as models for inferring the limits of hominin arboreality. PMID:23277565

Workplace support, discrimination, and person-organization fit: tests of the theory of work adjustment with LGB individuals.

PubMed

Velez, Brandon L; Moradi, Bonnie

2012-07-01

The present study explored the links of 2 workplace contextual variables--perceptions of workplace heterosexist discrimination and lesbian, gay, and bisexual (LGB)-supportive climates--with job satisfaction and turnover intentions in a sample of LGB employees. An extension of the theory of work adjustment (TWA) was used as the conceptual framework for the study; as such, perceived person-organization (P-O) fit was tested as a mediator of the relations between the workplace contextual variables and job outcomes. Data were analyzed from 326 LGB employees. Zero-order correlations indicated that perceptions of workplace heterosexist discrimination and LGB-supportive climates were correlated in expected directions with P-O fit, job satisfaction, and turnover intentions. Structural equation modeling (SEM) was used to compare multiple alternative measurement models evaluating the discriminant validity of the 2 workplace contextual variables relative to one another, and the 3 TWA job variables relative to one another; SEM was also used to test the hypothesized mediation model. Comparisons of multiple alternative measurement models supported the construct distinctiveness of the variables of interest. The test of the hypothesized structural model revealed that only LGB-supportive climates (and not workplace heterosexist discrimination) had a unique direct positive link with P-O fit and, through the mediating role of P-O fit, had significant indirect positive and negative relations with job satisfaction and turnover intentions, respectively. Moreover, P-O fit had a significant indirect negative link with turnover intentions through job satisfaction.

Measuring the Mass of a Pre-Main Sequence Binary Star Through the Orbit of TWA 5A

NASA Astrophysics Data System (ADS)

Konopacky, Q. M.; Ghez, A. M.; McCabe, C.; Duchene, G.; Macintosh, B. A.

2005-12-01

We present the results of a five year monitoring campaign of the close binary TWA 5Aab in the TW Hydrae association, using speckle and adaptive optics on the W.M. Keck 10 m telescopes. These measurements were taken as part of our ongoing monitoring of pre-main sequence (PMS) binaries in an effort to increase the number of dynamically determined PMS masses and thereby calibrate the theoretical PMS evolutionary tracks. Our observations have allowed us to obtain the first determination of this system's astrometric orbit. We find an orbital period of 5.55 ± 0.07 years and a semi-major axis of 0.063 arcsec ± 0.004 arcsec. Combining these results with a kinematic distance, we calculate a total mass of 0.70 ± 0.24 M⊙ for this system. This mass measurement, as well as the estimated age of this system, are in best agreement with the model predictions of Baraffe et al. (1998), but are also consistent to within 1.6σ of all other models considered. Our formal significance is low due to our proper accounting of correlated uncertainties; these correlations are important and generally not accounted for in comparisons of this kind. Nonetheless, with only a few more years of observation, these models will be easily distinguished. Support for this work was provided by the NASA Astrobiology Institute, the NSF Science & Technology Center for AO, managed by UCSC (AST-9876783), and the Packard Foundation.

The Diesel Exhaust in Miners Study: II. Exposure monitoring surveys and development of exposure groups.

PubMed

Coble, Joseph B; Stewart, Patricia A; Vermeulen, Roel; Yereb, Daniel; Stanevich, Rebecca; Blair, Aaron; Silverman, Debra T; Attfield, Michael

2010-10-01

Air monitoring surveys were conducted between 1998 and 2001 at seven non-metal mining facilities to assess exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), for an epidemiologic study of miners exposed to DE. Personal exposure measurements were taken on workers in a cross-section of jobs located underground and on the surface. Air samples taken to measure REC were also analyzed for respirable organic carbon (ROC). Concurrent measurements to assess exposure to nitric oxide (NO) and nitrogen dioxide (NO₂), two gaseous components of DE, were also taken. The REC measurements were used to develop quantitative estimates of average exposure levels by facility, department, and job title for the epidemiologic analysis. Each underground job was assigned to one of three sets of exposure groups from specific to general: (i) standardized job titles, (ii) groups of standardized job titles combined based on the percentage of time in the major underground areas, and (iii) larger groups based on similar area carbon monoxide (CO) air concentrations. Surface jobs were categorized based on their use of diesel equipment and proximity to DE. A total of 779 full-shift personal measurements were taken underground. The average REC exposure levels for underground jobs with five or more measurements ranged from 31 to 58 μg m⁻³ at the facility with the lowest average exposure levels and from 313 to 488 μg m⁻³ at the facility with the highest average exposure levels. The average REC exposure levels for surface workers ranged from 2 to 6 μg m⁻³ across the seven facilities. There was much less contrast in the ROC compared with REC exposure levels measured between surface and underground workers within each facility, as well as across the facilities. The average ROC levels underground ranged from 64 to 195 μg m⁻³, while on the surface, the average ROC levels ranged from 38 to 71 μg m⁻³ by facility, an ∼2- to 3-fold difference. The average NO and NO₂ levels underground ranged from 0.20 to 1.49 parts per million (ppm) and from 0.10 to 0.60 ppm, respectively, and were ∼10 times higher than levels on the surface, which ranged from 0.02 to 0.11 ppm and from 0.01 to 0.06 ppm, respectively. The ROC, NO, and NO₂ concentrations underground were correlated with the REC levels (r = 0.62, 0.71, and 0.62, respectively). A total of 80% of the underground jobs were assigned an exposure estimate based on measurements taken for the specific job title or for other jobs with a similar percentage of time spent in the major underground work areas. The average REC exposure levels by facility were from 15 to 64 times higher underground than on the surface. The large contrast in exposure levels measured underground versus on the surface, along with the differences between the mining facilities and between underground jobs within the facilities resulted in a wide distribution in the exposure estimates for evaluation of exposure-response relationships in the epidemiologic analyses.

An evaluation of the impact of flooring types on exposures to fine and coarse particles within the residential micro-environment using CONTAM.

PubMed

Bramwell, Lisa; Qian, Jing; Howard-Reed, Cynthia; Mondal, Sumona; Ferro, Andrea R

2016-01-01

Typical resuspension activities within the home, such as walking, have been estimated to contribute up to 25% of personal exposures to PM10. Chamber studies have shown that for moderate walking intensities, flooring type can impact the rate at which particles are re-entrained into the air. For this study, the impact of residential flooring type on incremental average daily (24 h) time-averaged exposure was investigated. Distributions of incremental time-averaged daily exposures to fine and coarse PM while walking within the residential micro-environment were predicted using CONTAM, the multizone airflow and contaminant transport program of the National Institute of Standards and Technology. Knowledge of when and where a person was walking was determined by randomly selecting 490 daily diaries from the EPA's consolidated human activity database (CHAD). On the basis of the results of this study, residential flooring type can significantly impact incremental time-averaged daily exposures to coarse and fine particles (α=0.05, P<0.05, N=490, Kruskal-Wallis test) with high-density cut pile carpeting resulting in the highest exposures. From this study, resuspension from walking within the residential micro-environment contributed 6-72% of time-averaged daily exposures to PM10.

Are occupational exposure limits becoming more alike within the European Union?

PubMed

Schenk, Linda; Hansson, Sven Ove; Rudén, Christina; Gilek, Michael

2008-10-01

The occupational exposure limits (OELs) established by seven different national regulatory agencies of EU member states are compared with those of the European Commission (EC). The comparison concerned: (1) what chemicals have been selected, (2) the average level of exposure limits for all chemicals, and (3) the similarity between the OELs of different EU member states and the OELs recommended by the European Commission. The average level of the exposure limits has declined during the past 10 years in four of the five countries in our study for which historical data were available to us. Poland has not changed its level noticeably and Germany has increased it. Since the first list of indicative OELs was established by the EC, a few of the EU exposure limits have been lowered. The similarity index indicates that the exposure limits of EU member states are converging towards the European Commission's recommended OELs. Still, the average level of OELs differs between organizations--the Estonian OELs are on average 35% higher than the Polish OELs.

Influence of mobile phone traffic on base station exposure of the general public.

PubMed

Joseph, Wout; Verloock, Leen

2010-11-01

The influence of mobile phone traffic on temporal radiofrequency exposure due to base stations during 7 d is compared for five different sites with Erlang data (representing average mobile phone traffic intensity during a period of time). The time periods of high exposure and high traffic during a day are compared and good agreement is obtained. The minimal required measurement periods to obtain accurate estimates for maximal and average long-period exposure (7 d) are determined. It is shown that these periods may be very long, indicating the necessity of new methodologies to estimate maximal and average exposure from short-period measurement data. Therefore, a new method to calculate the fields at a time instant from fields at another time instant using normalized Erlang values is proposed. This enables the estimation of maximal and average exposure during a week from short-period measurements using only Erlang data and avoids the necessity of long measurement times.

The Diesel Exhaust in Miners Study: II. Exposure Monitoring Surveys and Development of Exposure Groups

PubMed Central

Coble, Joseph B.; Stewart, Patricia A.; Vermeulen, Roel; Yereb, Daniel; Stanevich, Rebecca; Blair, Aaron; Silverman, Debra T.; Attfield, Michael

2010-01-01

Air monitoring surveys were conducted between 1998 and 2001 at seven non-metal mining facilities to assess exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), for an epidemiologic study of miners exposed to DE. Personal exposure measurements were taken on workers in a cross-section of jobs located underground and on the surface. Air samples taken to measure REC were also analyzed for respirable organic carbon (ROC). Concurrent measurements to assess exposure to nitric oxide (NO) and nitrogen dioxide (NO2), two gaseous components of DE, were also taken. The REC measurements were used to develop quantitative estimates of average exposure levels by facility, department, and job title for the epidemiologic analysis. Each underground job was assigned to one of three sets of exposure groups from specific to general: (i) standardized job titles, (ii) groups of standardized job titles combined based on the percentage of time in the major underground areas, and (iii) larger groups based on similar area carbon monoxide (CO) air concentrations. Surface jobs were categorized based on their use of diesel equipment and proximity to DE. A total of 779 full-shift personal measurements were taken underground. The average REC exposure levels for underground jobs with five or more measurements ranged from 31 to 58 μg m−3 at the facility with the lowest average exposure levels and from 313 to 488 μg m−3 at the facility with the highest average exposure levels. The average REC exposure levels for surface workers ranged from 2 to 6 μg m−3 across the seven facilities. There was much less contrast in the ROC compared with REC exposure levels measured between surface and underground workers within each facility, as well as across the facilities. The average ROC levels underground ranged from 64 to 195 μg m−3, while on the surface, the average ROC levels ranged from 38 to 71 μg m−3 by facility, an ∼2- to 3-fold difference. The average NO and NO2 levels underground ranged from 0.20 to 1.49 parts per million (ppm) and from 0.10 to 0.60 ppm, respectively, and were ∼10 times higher than levels on the surface, which ranged from 0.02 to 0.11 ppm and from 0.01 to 0.06 ppm, respectively. The ROC, NO, and NO2 concentrations underground were correlated with the REC levels (r = 0.62, 0.71, and 0.62, respectively). A total of 80% of the underground jobs were assigned an exposure estimate based on measurements taken for the specific job title or for other jobs with a similar percentage of time spent in the major underground work areas. The average REC exposure levels by facility were from 15 to 64 times higher underground than on the surface. The large contrast in exposure levels measured underground versus on the surface, along with the differences between the mining facilities and between underground jobs within the facilities resulted in a wide distribution in the exposure estimates for evaluation of exposure–response relationships in the epidemiologic analyses. PMID:20876232

Developmental and hematological responses to low level continuous exposure of nitrogen dioxide in mice

NASA Technical Reports Server (NTRS)

Singh, J.

1977-01-01

Young healthy mice were continuously exposed to 0ppm, 0.5ppm, 1.0ppm and 5ppm nitrogen dioxide gas for eight weeks. Nitrogen dioxide exposure for eight weeks decreased the average weight of mice, increased the average weight of lungs, heart, and brain and decreased the average weight of liver. Nitrogen dioxide exposure did not have any effects on the WBC and RBC in mice blood but it increased the HCT and HGB in mice blood. Nitrogen dioxide exposure increased the MCV and decreased the MCH and MCHC in mice blood.

Waif goodbye! Average-size female models promote positive body image and appeal to consumers.

PubMed

Diedrichs, Phillippa C; Lee, Christina

2011-10-01

Despite consensus that exposure to media images of thin fashion models is associated with poor body image and disordered eating behaviours, few attempts have been made to enact change in the media. This study sought to investigate an effective alternative to current media imagery, by exploring the advertising effectiveness of average-size female fashion models, and their impact on the body image of both women and men. A sample of 171 women and 120 men were assigned to one of three advertisement conditions: no models, thin models and average-size models. Women and men rated average-size models as equally effective in advertisements as thin and no models. For women with average and high levels of internalisation of cultural beauty ideals, exposure to average-size female models was associated with a significantly more positive body image state in comparison to exposure to thin models and no models. For men reporting high levels of internalisation, exposure to average-size models was also associated with a more positive body image state in comparison to viewing thin models. These findings suggest that average-size female models can promote positive body image and appeal to consumers.

DEVELOMENT AND EVALUATION OF A MODEL FOR ESTIMATING LONG-TERM AVERAGE OZONE EXPOSURES TO CHILDREN

EPA Science Inventory

Long-term average exposures of school-age children can be modelled using longitudinal measurements collected during the Harvard Southern California Chronic Ozone Exposure Study over a 12-month period: June, 1995-May, 1996. The data base contains over 200 young children with perso...

Commuter exposure to ultrafine particles in different urban locations, transportation modes and routes

NASA Astrophysics Data System (ADS)

Ragettli, Martina S.; Corradi, Elisabetta; Braun-Fahrländer, Charlotte; Schindler, Christian; de Nazelle, Audrey; Jerrett, Michael; Ducret-Stich, Regina E.; Künzli, Nino; Phuleria, Harish C.

2013-10-01

A better understanding of ultrafine particle (UFP) exposure in different urban transport microenvironments is important for epidemiological exposure assessments and for policy making. Three sub-studies were performed to characterize personal exposure to UFP concentration and average particle size distribution diameters in frequently traveled commuter microenvironments in the city of Basel, Switzerland. First, the spatial variation of sidewalk UFP exposures within urban areas and transport-specific microenvironments was explored. Second, exposure to UFP concentration and average particle size were quantified for five modes of transportation (walking, bicycle, bus, tram, car) during different times of the day and week, along the same route. Finally, the contribution of bicycle commuting along two different routes (along main roads, away from main roads) to total daily exposures was assessed by 24-h personal measurements. In general, smaller average particle sizes and higher UFP levels were measured at places and for travel modes in close proximity to traffic. Average trip UFP concentrations were higher in car (31,784 particles cm-³) and on bicycle (22,660 particles cm-³) compared to walking (19,481 particles cm-³) and public transportation (14,055-18,818 particles cm-³). Concentrations were highest for all travel modes during weekday morning rush hours, compared to other time periods. UFP concentration was lowest in bus, regardless of time period. Bicycle travel along main streets between home and work place (24 min on average) contributed 21% and 5% to total daily UFP exposure in winter and summer, respectively. Contribution of bicycle commutes to total daily UFP exposure could be reduced by half if main roads are avoided. Our results show the importance of considering commuter behavior and route choice in exposure assessment studies.

Combining near- and far-field exposure for an organ-specific and whole-body RF-EMF proxy for epidemiological research: a reference case.

PubMed

Lauer, Oliver; Frei, Patrizia; Gosselin, Marie-Christine; Joseph, Wout; Röösli, Martin; Fröhlich, Jürg

2013-07-01

A framework for the combination of near-field (NF) and far-field (FF) radio frequency electromagnetic exposure sources to the average organ and whole-body specific absorption rates (SARs) is presented. As a reference case, values based on numerically derived SARs for whole-body and individual organs and tissues are combined with realistic exposure data, which have been collected using personal exposure meters during the Swiss Qualifex study. The framework presented can be applied to any study region where exposure data is collected by appropriate measurement equipment. Based on results derived from the data for the region of Basel, Switzerland, the relative importance of NF and FF sources to the personal exposure is examined for three different study groups. The results show that a 24-h whole-body averaged exposure of a typical mobile phone user is dominated by the use of his or her own mobile phone when a Global System for Mobile Communications (GSM) 900 or GSM 1800 phone is used. If only Universal Mobile Telecommunications System (UMTS) phones are used, the user would experience a lower exposure level on average caused by the lower average output power of UMTS phones. Data presented clearly indicate the necessity of collecting band-selective exposure data in epidemiological studies related to electromagnetic fields. Copyright © 2013 Wiley Periodicals, Inc.

Modulation of the SSTA decadal variation on ENSO events and relationships of SSTA With LOD,SOI, etc

NASA Astrophysics Data System (ADS)

Liao, D. C.; Zhou, Y. H.; Liao, X. H.

2007-01-01

Interannual and decadal components of the length of day (LOD), Southern Oscillation Index (SOI) and Sea Surface Temperature anomaly (SSTA) in Nino regions are extracted by band-pass filtering, and used for research of the modulation of the SSTA on the ENSO events. Results show that besides the interannual components, the decadal components in SSTA have strong impacts on monitoring and representing of the ENSO events. When the ENSO events are strong, the modulation of the decadal components of the SSTA tends to prolong the life-time of the events and enlarge the extreme anomalies of the SST, while the ENSO events, which are so weak that they can not be detected by the interannual components of the SSTA, can also be detected with the help of the modulation of the SSTA decadal components. The study further draws attention to the relationships of the SSTA interannual and decadal components with those of LOD, SOI, both of the sea level pressure anomalies (SLPA) and the trade wind anomalies (TWA) in tropic Pacific, and also with those of the axial components of the atmospheric angular momentum (AAM) and oceanic angular momentum (OAM). Results of the squared coherence and coherent phases among them reveal close connections with the SSTA and almost all of the parameters mentioned above on the interannual time scales, while on the decadal time scale significant connections are among the SSTA and SOI, SLPA, TWA, ?3w and ?3w+v as well, and slight weaker connections between the SSTA and LOD, ?3pib and ?3bp

Conceptual study of an ICRH traveling-wave antenna system for low-coupling conditions as expected in DEMO

NASA Astrophysics Data System (ADS)

Ragona, R.; Messiaen, A.

2016-07-01

For the central heating of a fusion reactor ion cyclotron radio frequency heating (ICRH) is the first choice method as it is able to couple RF power to the ions without density limit. The drawback of this heating method is the problem of excitation of the magneto-sonic wave through the plasma boundary layer from the antenna located along the wall, without exceeding its voltage standoff. The amount of coupling depends on the antenna excitation and the surface admittance at the antenna output due to the plasma profile. The paper deals with the optimization of the antenna excitation by the use of sections of traveling-wave antennas (TWAs) distributed all along the reactor wall between the blanket modules. They are mounted and fed in resonant ring system(s). First, the physics of the coupling of a strap array is studied by simple models and the coupling code ANTITER II. Then, after the study of the basic properties of a TWA section, its feeding problem is solved by hybrids driving them in resonant ring circuit(s). The complete modeling is obtained from the matrices of the TWA sections connected to one of the feeding hybrid(s). The solution is iterated with the coupling code to determine the loading for a reference low-coupling ITER plasma profile. The resulting wave pattern up to the plasma bulk is derived. The proposed system is totally load resilient and allows us to obtain a very selective exciting wave spectrum. A discussion of some practical implementation problems is added.

Characterization of five passive sampling devices for monitoring of pesticides in water.

PubMed

Ahrens, Lutz; Daneshvar, Atlasi; Lau, Anna E; Kreuger, Jenny

2015-07-31

Five different passive sampler devices were characterized under laboratory conditions for measurement of 124 legacy and current used pesticides in water. In addition, passive sampler derived time-weighted average (TWA) concentrations were compared to time-integrated active sampling in the field. Sampling rates (RS) and passive sampler-water partition coefficients (KPW) were calculated for individual pesticides using silicone rubber (SR), polar organic chemical integrative sampler (POCIS)-A, POCIS-B, Chemcatcher(®) SDB-RPS and Chemcatcher(®) C18. The median RS (Lday(-1)) decreased as follows: SR (0.86)>POCIS-B (0.22)>POCIS-A (0.18)>Chemcatcher(®) SDB-RPS (0.05)>Chemcatcher(®) C18 (0.02), while the median logKPW (Lkg(-1)) decreased as follows: POCIS-B (4.78)>POCIS-A (4.56)>Chemcatcher(®) SDB-RPS (3.17)>SR (3.14)>Chemcatcher(®)C18 (2.71). The uptake of the selected compounds depended on their physicochemical properties, i.e. SR showed a better uptake for more hydrophobic compounds (log octanol-water partition coefficient (KOW)>5.3), whereas POCIS-A, POCIS-B and Chemcatcher(®) SDB-RPS were more suitable for hydrophilic compounds (logKOW<0.70). Overall, the comparison between passive sampler and time-integrated active sampler concentrations showed a good agreement and the tested passive samplers were suitable for capturing compounds with a wide range of KOW's in water. Copyright © 2015 Elsevier B.V. All rights reserved.

The detection of T-wave variation linked to arrhythmic risk: an industry perspective.

PubMed

Xue, Joel; Rowlandson, Ian

2013-01-01

Although the scientific literature contains ample descriptions of peculiar patterns of repolarization linked to arrhythmic risk, the objective quantification and classification of these patterns continues to be a challenge that impacts their widespread adoption in clinical practice. To advance the science, computerized algorithms spawned in the academic environment have been essential in order to find, extract and measure these patterns. However, outside the strict control of a core lab, these algorithms are exposed to poor quality signals and need to be effective in the presence of different forms of noise that can either obscure or mimic the T-wave variation (TWV) of interest. To provide a practical solution that can be verified and validated for the market, important tradeoffs need to be made that are based on an intimate understanding of the end-user as well as the key characteristics of either the signal or the noise that can be used by the signal processing engineer to best differentiate them. To illustrate this, two contemporary medical devices used for quantifying T-wave variation are presented, including the modified moving average (MMA) for the detection of T-wave Alternans (TWA) and the quantification of T-wave shape as inputs to the Morphology Combination Score (MCS) for the trending of drug-induced repolarization abnormalities. © 2013 Elsevier Inc. All rights reserved.

Breakthrough indicator for aromatic VOCs using needle trap samplers for activated carbon adsorbent.

PubMed

Cheng, Wen-Hsi; Jiang, Jia-Rong; Huang, Yi-Ning; Huang, Shiun-Chian; Yu, Yan-Pin

2012-08-01

Internal circulation cabinets equipped with granular activated carbon (GAC) for adsorbing volatile organic compounds (VOCs) are widely used to store bottles containing organic solvents in universities, colleges, and hospital laboratories throughout Taiwan. This work evaluates the VOC adsorption capacities of GAC using various adsorption times for gas stream mixtures of 100 ppm toluene and 100 ppm o-xylene. Additionally, needle trap sampling (NTS) technology was used to indicate the time for renewing the GAC to avoid VOC breakthrough from adsorbents. Experimental results demonstrate that the proposed models can linearly express toluene and o-xylene adsorption capacities as the natural logarithm of adsorption time (ln(t)) and can accurately simulate the equilibrium adsorption capacities (Qe, g VOCs/g GAC) for gaseous toluene and o-xylene. The NTS, packed with 60-80 mesh divinylbenzene (DVB) particles, was compared in terms of extraction efficiency by simultaneously using the 75-microm Carboxen/polydimethylsiloxane-solid-phase microextraction (Carboxen/PDMS-SPME) fiber for time-weighted average (TWA) sampling, and experimental results indicated that the packed DVB-NTS achieved higher toluene extraction rates. Additionally, the NTS installed in the outlet air stream for adsorbing toluene and o-xylene exhausted through GAC accurately indicated toluene and o-xylene breakthrough times of 4700-5000 min. The GAC-NTS operational instructions to indicate the replacing time of adsorbent in the internal circulation cabinets are also included in this paper.

Assessment of bioavailable fraction of POPS in surface water bodies in Johannesburg City, South Africa, using passive samplers: an initial assessment.

PubMed

Amdany, Robert; Chimuka, Luke; Cukrowska, Ewa; Kukučka, Petr; Kohoutek, Jiří; Tölgyessy, Peter; Vrana, Branislav

2014-09-01

In this study, the semipermeable membrane device (SPMD) passive samplers were used to determine freely dissolved concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in selected water bodies situated in and around Johannesburg City, South Africa. The devices were deployed for 14 days at each sampling site in spring and summer of 2011. Time weighted average (TWA) concentrations of the water-borne contaminants were calculated from the amounts of analytes accumulated in the passive samplers. In the area of interest, concentrations of analytes in water ranged from 33.5 to 126.8 ng l(-1) for PAHs, from 20.9 to 120.9 pg l(-1) for PCBs and from 0.2 to 36.9 ng l(-1) for OCPs. Chlorinated pesticides were mainly composed of hexachlorocyclohexanes (HCHs) (0.15-36.9 ng l(-1)) and dichlorodiphenyltrichloromethane (DDT) with its metabolites (0.03-0.55 ng l(-1)). By applying diagnostic ratios of certain PAHs, identification of possible sources of the contaminants in the various sampling sites was performed. These ratios were generally inclined towards pyrogenic sources of pollution by PAHs in all study sites except in the Centurion River (CR), Centurion Lake (CL) and Airport River (AUP) that indicated petrogenic origins. This study highlights further need to map up the temporal and spatial variations of these POPs using passive samplers.

Respiratory symptoms associated with low level sulphur dioxide exposure in silicon carbide production workers.

PubMed Central

Osterman, J W; Greaves, I A; Smith, T J; Hammond, S K; Robins, J M; Thériault, G

1989-01-01

Relations between pulmonary symptoms and exposure to respirable dust and sulphur dioxide (SO2) were evaluated for 145 silicon carbide (SiC) production workers with an average of 13.9 (range 3-41) years of experience in this industry. Eight hour time weighted average exposures to SO2 were 1.5 ppm or less with momentary peaks up to 4 ppm. Cumulative SO2 exposure averaged 1.94 (range 0.02-19.5) ppm-years. Low level respirable dust exposures also occurred (0.63 +/- 0.26 mg/m3). After adjusting for age and current smoking status in multiple logistic regression models, highly significant, positive, dose dependent relations were found between cumulative and average exposure to SO2, and symptoms of usual and chronic phlegm, usual and chronic wheeze, and mild exertional dyspnoea. Mild and moderate dyspnoea were also associated with most recent exposure to SO2. Cough was not associated with SO2. No pulmonary symptoms were associated with exposure to respirable dust nor were any symptoms attributable to an interaction between dust and SO2. Cigarette smoking was strongly associated with cough, phlegm, and wheezing, but not dyspnoea. A greater than additive (synergistic) effect between smoking and exposure to SO2 was present for most symptoms. These findings suggest that long term, variable exposure to SO2 at 1.5 ppm or less was associated with significantly raised rates of phlegm, wheezing, and mild dyspnoea in SiC production workers, and that current threshold limits for SO2 may not adequately protect workers in this industry. PMID:2789966

Light Exposure and Eye Growth in Childhood.

PubMed

Read, Scott A; Collins, Michael J; Vincent, Stephen J

2015-10-01

The purpose of this study was to examine the relationship between objectively measured ambient light exposure and longitudinal changes in axial eye growth in childhood. A total of 101 children (41 myopes and 60 nonmyopes), 10 to 15 years of age participated in this prospective longitudinal observational study. Axial eye growth was determined from measurements of ocular optical biometry collected at four study visits over an 18-month period. Each child's mean daily light exposure was derived from two periods (each 14 days long) of objective light exposure measurements from a wrist-worn light sensor. Over the 18-month study period, a modest but statistically significant association between greater average daily light exposure and slower axial eye growth was observed (P = 0.047). Other significant predictors of axial eye growth in this population included children's refractive error group (P < 0.001), sex (P < 0.01), and age (P < 0.001). Categorized according to their objectively measured average daily light exposure and adjusting for potential confounders (age, sex, baseline axial length, parental myopia, nearwork, and physical activity), children experiencing low average daily light exposure (mean daily light exposure: 459 ± 117 lux, annual eye growth: 0.13 mm/y) exhibited significantly greater eye growth than children experiencing moderate (842 ± 109 lux, 0.060 mm/y), and high (1455 ± 317 lux, 0.065 mm/y) average daily light exposure levels (P = 0.01). In this population of children, greater daily light exposure was associated with less axial eye growth over an 18-month period. These findings support the role of light exposure in the documented association between time spent outdoors and childhood myopia.

Occupational exposure to NDMA and NMor in the European rubber industry.

PubMed

de Vocht, F; Burstyn, I; Straif, K; Vermeulen, R; Jakobsson, K; Nichols, L; Peplonska, B; Taeger, D; Kromhout, H

2007-03-01

Many nitrosamines are suspected of being human carcinogens, with the highest concentrations in the environment being measured in the rubber industry. Time trends of personal exposure to N-nitrosodimethylamine (NDMA) and to N-nitrosomorpholine (NMor) during the past two decades in the German rubber industry were analysed and compared with cross-sectional studies in the same period in the Netherlands, Poland, the UK and Sweden. In the majority of the surveyed departments exposures reduced over time, but considerable heterogeneity was present between departments and sectors. Significant reductions were primarily found in curing and post-treating departments and ranged from -3% year(-1) to -19% year(-1). In contrast, NDMA levels increased (+13% year(-1)) in maintenance and engineering in the tyres industry. Average NDMA-levels in general rubber goods (GRG) and NMor-levels in tyre production in Germany did not decrease significantly in the past two decades, whereas NDMA-levels in tyre production (-10% year(-1)) and NMor-levels in GRG (-7% year(-1)) declined significantly after the introduction of an exposure limit for total nitrosamines in Germany in 1988. Confidence intervals of average exposures in other studied countries largely overlap trends observed in Germany. Exposure to N-nitrosamines decreased on average two-to-five fold in the German rubber industry with comparable concentration levels in other European countries. Although average levels are well below the current limits exposure has not been eliminated, and incidental high exposures do still occur.

Detection and classification of gaseous sulfur compounds by solid electrolyte cyclic voltammetry of cermet sensor array.

PubMed

Kramer, Kirsten E; Rose-Pehrsson, Susan L; Hammond, Mark H; Tillett, Duane; Streckert, Holger H

2007-02-12

Electrochemical sensors composed of a ceramic-metallic (cermet) solid electrolyte are used for the detection of gaseous sulfur compounds SO(2), H(2)S, and CS(2) in a study involving 11 toxic industrial chemical (TIC) compounds. The study examines a sensor array containing four cermet sensors varying in electrode-electrolyte composition, designed to offer selectivity for multiple compounds. The sensors are driven by cyclic voltammetry to produce a current-voltage profile for each analyte. Raw voltammograms are processed by background subtraction of clean air, and the four sensor signals are concatenated to form one vector of points. The high-resolution signal is compressed by wavelet transformation and a probabilistic neural network is used for classification. In this study, training data from one sensor array was used to formulate models which were validated with data from a second sensor array. Of the 11 gases studied, 3 that contained sulfur produced the strongest responses and were successfully analyzed when the remaining compounds were treated as interferents. Analytes were measured from 10 to 200% of their threshold-limited value (TLV) according to the 8-h time weighted average (TWA) exposure limits defined by the National Institute of Occupational Safety and Health (NIOSH). True positive classification rates of 93.3, 96.7, and 76.7% for SO(2), H(2)S, and CS(2), respectively, were achieved for prediction of one sensor unit when a second sensor was used for modeling. True positive rates of 83.3, 90.0, and 90.0% for SO(2), H(2)S, and CS(2), respectively, were achieved for the second sensor unit when the first sensor unit was used for modeling. Most of the misclassifications were for low concentration levels (such 10-25% TLV) in which case the compound was classified as clean air. Between the two sensors, the false positive rates were 2.2% or lower for the three sulfur compounds, 0.9% or lower for the interferents (eight remaining analytes), and 5.8% or lower for clean air. The cermet sensor arrays used in this analysis are rugged, low cost, reusable, and show promise for multiple compound detection at parts-per-million (ppm) levels.

Contrast Medium Exposure During Computed Tomography and Risk of Development of End-Stage Renal Disease in Patients With Chronic Kidney Disease

PubMed Central

Hsieh, Ming-Shun; Chiu, Chien-Shan; How, Chorng-Kuang; Chiang, Jen-Huai; Sheu, Meei-Ling; Chen, Wen-Chi; Lin, Hsuan-Jen; Hsieh, Vivian Chia-Rong; Hu, Sung-Yuan

2016-01-01

Abstract The aim of the study was to investigate the long-term association between contrast medium exposure during computed tomography (CT) and the subsequent development of end-stage renal disease (ESRD) in patients with chronic kidney disease (CKD). We conducted a population-based cohort study using Taiwan's National Health Insurance Research Database. A total of 7100 patients with nonadvanced CKD who underwent contrast medium-enhanced CT were identified and served as the study cohort. To avoid selection bias, we used the propensity score to match 7100 nonadvanced CKD patients, who underwent noncontrast medium-enhanced CT to serve as the comparison cohort. The age, sex, index year, and frequency of undergoing CTs were also matched between the study and comparison cohorts. Participants were followed until a new diagnosis of ESRD or December 31, 2011. Hazard ratios (HRs) with 95% confidence interval (95% CI) were calculated using the Cox proportional hazards regression. Contrast medium exposure was not identified as a risk factor for developing ESRD in nonadvanced CKD patients after confounders adjustment (adjusted HR = 0.91; 95% CI, 0.66–1.26; P = 0.580). We further divided the patients who underwent CTs with contrast medium use into ≤1 exposure per year on average, >1 and <2 exposure per year on average, and ≥2 exposure per year on average. After adjusting for confounders, we identified a much higher risk for developing ESRD in the 2 groups of >1 and <2 exposure per year on average and ≥2 exposure per year on average (adjusted HR = 8.13; 95% CI, 5.57–11.87 and adjusted HR = 12.08; 95% CI, 7.39–19.75, respectively) compared with the patients who underwent CTs without contrast medium use. This long-term follow-up study demonstrated that contrast medium exposure was not associated with an increased risk of ESRD development in nonadvanced CKD patients. PMID:27100424

Influence of N-hexane inhalation on the enantioselective pharmacokinetics and metabolism of verapamil in rats.

PubMed

Mateus, Fabiano H; Lepera, José S; Marques, Maria Paula; Boralli, Vanessa B; Lanchote, Vera L

2010-01-01

Verapamil (VER) is commercialized as a racemic mixture of the (+)-(R)-VER and (-)-(S)-VER enantiomers. VER is biotransformed into norverapamil (NOR) and other metabolites through CYP-dependent pathways. N-hexane is a solvent that can alter the metabolism of CYP-dependent drugs. The present study investigated the influence of n-hexane (nose-only inhalation exposure chamber at concentrations of 88, 176, and 352 mg/m3) on the kinetic disposition of the (+)-(R)-VER, (-)-(S)-VER, (R)-NOR and (S)-NOR in rats treated with a single dose of racemic VER (10 mg/kg). VER and NOR enantiomers in rat plasma was analyzed by LC-MS/MS (m/z = 441.3 > 165.5 for the NOR and m/z 455.3 > 165.5 for the VER enantiomers) using a Chiralpak AD column. Pharmacokinetic analysis was performed using a monocompartmental model. The pharmacokinetics of VER was enantioselective in control rats, with higher plasma proportions of the (-)-(S)-VER eutomer (AUC(0-infinity) = 250.8 vs. 120.4 ng/ml/h; P < or = 0.05, Wilcoxon test). The (S)-NOR metabolite was also found to accumulate in plasma of control animals, with an S/R AUC(0-infinity) ratio of 1.5. The pharmacokinetic parameters AUC(0-infinity), Cl/F, Vd/F, and t(1/2) obtained for VER and NOR enantiomers were not altered by nose-only exposure to n-hexane at concentrations of 88, 176, or 352 mg/m3 (P > 0.05, Kruskal-Wallis test). However, the verapamil kinetic disposition was not enantioselective for the animals exposed to n-hexane at concentrations equal to or higher than the TLV-TWA. This finding is relevant considering that the (-)-(S)-VER eutomer is 10-20 times more potent than R-(+)-VER in terms of its chronotropic effect on atrioventricular conduction in rats and humans. Copyright 2009 Wiley-Liss, Inc.

Adolescent Changes in Homeostatic Regulation of EEG Activity in the Delta and Theta Frequency Bands during NREM Sleep

PubMed Central

Campbell, Ian G.; Darchia, Nato; Higgins, Lisa M.; Dykan, Igor V.; Davis, Nicole M.; de Bie, Evan; Feinberg, Irwin

2011-01-01

Study Objectives: Slow wave EEG activity in NREM sleep decreases by more than 60% between ages 10 and 20 years. Slow wave EEG activity also declines across NREM periods (NREMPs) within a night, and this decline is thought to represent the dynamics of sleep homeostasis. We used longitudinal data to determine whether these homeostatic dynamics change across adolescence. Design: All-night sleep EEG was recorded semiannually for 6 years. Setting: EEG was recorded with ambulatory recorders in the subjects' homes. Participants: Sixty-seven subjects in 2 cohorts, one starting at age 9 and one starting at age 12 years. Measurements and Results: For NREM delta (1-4 Hz) and theta (4-8 Hz) EEG, we tested whether the proportion of spectral energy contained in the first NREMP changes with age. We also tested for age changes in the parameters of the process S exponential decline. For both delta and theta, the proportion of energy in the first NREMP declined significantly across ages 9 to 18 years. Process S parameters SWA0 and TWA0, respectively, represent slow wave (delta) activity and theta wave activity at the beginning of the night. SWA0 and TWA0 declined significantly (P < 0.0001) across ages 9 to 18. Conclusions: These declines indicate that the intensity of the homeostatic or restorative processes at the beginning of sleep diminished across adolescence. We propose that this change in sleep regulation is caused by the synaptic pruning that occurs during adolescent brain maturation. Citation: Campbell IG; Darchia N; Higgins LM; Dykan IV; Davis NM; de Bie E; Feinberg I. Adolescent changes in homeostatic regulation of EEG activity in the delta and theta frequency bands during NREM sleep. SLEEP 2011;34(1):83-91. PMID:21203377

Sudden cardiac death and pump failure death prediction in chronic heart failure by combining ECG and clinical markers in an integrated risk model

PubMed Central

Orini, Michele; Mincholé, Ana; Monasterio, Violeta; Cygankiewicz, Iwona; Bayés de Luna, Antonio; Martínez, Juan Pablo

2017-01-01

Background Sudden cardiac death (SCD) and pump failure death (PFD) are common endpoints in chronic heart failure (CHF) patients, but prevention strategies are different. Currently used tools to specifically predict these endpoints are limited. We developed risk models to specifically assess SCD and PFD risk in CHF by combining ECG markers and clinical variables. Methods The relation of clinical and ECG markers with SCD and PFD risk was assessed in 597 patients enrolled in the MUSIC (MUerte Súbita en Insuficiencia Cardiaca) study. ECG indices included: turbulence slope (TS), reflecting autonomic dysfunction; T-wave alternans (TWA), reflecting ventricular repolarization instability; and T-peak-to-end restitution (ΔαTpe) and T-wave morphology restitution (TMR), both reflecting changes in dispersion of repolarization due to heart rate changes. Standard clinical indices were also included. Results The indices with the greatest SCD prognostic impact were gender, New York Heart Association (NYHA) class, left ventricular ejection fraction, TWA, ΔαTpe and TMR. For PFD, the indices were diabetes, NYHA class, ΔαTpe and TS. Using a model with only clinical variables, the hazard ratios (HRs) for SCD and PFD for patients in the high-risk group (fifth quintile of risk score) with respect to patients in the low-risk group (first and second quintiles of risk score) were both greater than 4. HRs for SCD and PFD increased to 9 and 11 when using a model including only ECG markers, and to 14 and 13, when combining clinical and ECG markers. Conclusion The inclusion of ECG markers capturing complementary pro-arrhythmic and pump failure mechanisms into risk models based only on standard clinical variables substantially improves prediction of SCD and PFD in CHF patients. PMID:29020031

[The airborne 1,3-butadiene concentrations in rubber and plastic processing plants].

PubMed

Yoshida, Toshiaki; Tainaka, Hidetsugu; Matsunaga, Ichiro; Goto, Sumio

2002-03-01

Environment pollution by 1,3-butadiene had considerably increased in Japan. The main cause of the pollution is the automotive exhaust gas, and leaks from factories, smoking, and burning of rubber and plastic products are considered to be minor sources. The object of this study was to determine the contamination levels of airborne 1,3-butadiene in factories processing rubber and plastics containing 1,3-butadiene. The concentrations of airborne 1,3-butadiene were measured in 21 plants (10 rubber processing plants and 11 plastics processing plants) in Osaka. 1,3-Butadiene in air was collected for 10 minutes with a charcoal tube and a portable small pump adjusted to a 250 ml/min flow rate. In each plant, indoor air samples at five points and an outdoor air sample at one point outside the plant were collected. The samples were subjected to gas chromatography/mass spectrometry after thermal desorption from the charcoal. The concentrations of airborne 1,3-butadiene in the rubber processing plants and the plastics processing plants were 0.14-2.20 micrograms/m3 (geometric mean: 0.48 microgram/m3) and 0.23-4.51 micrograms/m3 (geometric mean: 0.80 microgram/m3), respectively. In all plants examined, indoor 1,3-butadiene concentrations were higher than the outdoor concentrations around the plants. Therefore, 1,3-butadiene was considered to arise from the processing of rubber or plastics, but the indoor 1,3-butadiene concentrations were much lower than the PEL-TWA (1 ppm = 2.21 mg/m3) of OSHA and the TLV-TWA (2 ppm) of ACGIH. The concentrations in the plants with closed room conditions without ventilation were higher than the concentrations in the other plants. It was suggested that ventilation affected the 1,3-butadiene concentration in the plants.

Sudden cardiac death and pump failure death prediction in chronic heart failure by combining ECG and clinical markers in an integrated risk model.

PubMed

Ramírez, Julia; Orini, Michele; Mincholé, Ana; Monasterio, Violeta; Cygankiewicz, Iwona; Bayés de Luna, Antonio; Martínez, Juan Pablo; Laguna, Pablo; Pueyo, Esther

2017-01-01

Sudden cardiac death (SCD) and pump failure death (PFD) are common endpoints in chronic heart failure (CHF) patients, but prevention strategies are different. Currently used tools to specifically predict these endpoints are limited. We developed risk models to specifically assess SCD and PFD risk in CHF by combining ECG markers and clinical variables. The relation of clinical and ECG markers with SCD and PFD risk was assessed in 597 patients enrolled in the MUSIC (MUerte Súbita en Insuficiencia Cardiaca) study. ECG indices included: turbulence slope (TS), reflecting autonomic dysfunction; T-wave alternans (TWA), reflecting ventricular repolarization instability; and T-peak-to-end restitution (ΔαTpe) and T-wave morphology restitution (TMR), both reflecting changes in dispersion of repolarization due to heart rate changes. Standard clinical indices were also included. The indices with the greatest SCD prognostic impact were gender, New York Heart Association (NYHA) class, left ventricular ejection fraction, TWA, ΔαTpe and TMR. For PFD, the indices were diabetes, NYHA class, ΔαTpe and TS. Using a model with only clinical variables, the hazard ratios (HRs) for SCD and PFD for patients in the high-risk group (fifth quintile of risk score) with respect to patients in the low-risk group (first and second quintiles of risk score) were both greater than 4. HRs for SCD and PFD increased to 9 and 11 when using a model including only ECG markers, and to 14 and 13, when combining clinical and ECG markers. The inclusion of ECG markers capturing complementary pro-arrhythmic and pump failure mechanisms into risk models based only on standard clinical variables substantially improves prediction of SCD and PFD in CHF patients.

The importance of explicitly mapping instructional analogies in science education

NASA Astrophysics Data System (ADS)

Asay, Loretta Johnson

Analogies are ubiquitous during instruction in science classrooms, yet research about the effectiveness of using analogies has produced mixed results. An aspect seldom studied is a model of instruction when using analogies. The few existing models for instruction with analogies have not often been examined quantitatively. The Teaching With Analogies (TWA) model (Glynn, 1991) is one of the models frequently cited in the variety of research about analogies. The TWA model outlines steps for instruction, including the step of explicitly mapping the features of the source to the target. An experimental study was conducted to examine the effects of explicitly mapping the features of the source and target in an analogy during computer-based instruction about electrical circuits. Explicit mapping was compared to no mapping and to a control with no analogy. Participants were ninth- and tenth-grade biology students who were each randomly assigned to one of three conditions (no analogy module, analogy module, or explicitly mapped analogy module) for computer-based instruction. Subjects took a pre-test before the instruction, which was used to assign them to a level of previous knowledge about electrical circuits for analysis of any differential effects. After the instruction modules, students took a post-test about electrical circuits. Two weeks later, they took a delayed post-test. No advantage was found for explicitly mapping the analogy. Learning patterns were the same, regardless of the type of instruction. Those who knew the least about electrical circuits, based on the pre-test, made the most gains. After the two-week delay, this group maintained the largest amount of their gain. Implications exist for science education classrooms, as analogy use should be based on research about effective practices. Further studies are suggested to foster the building of research-based models for classroom instruction with analogies.

Association of Serum n-3/n-6 Polyunsaturated Fatty Acid Ratio With T-Wave Alternans in Patients With Ischemic Heart Disease.

PubMed

Nodera, Minoru; Suzuki, Hitoshi; Yamada, Shinya; Kamioka, Masashi; Kaneshiro, Takashi; Kamiyama, Yoshiyuki; Takeishi, Yasuchika

2015-01-01

Several studies have demonstrated that oral intake of n-3 polyunsaturated fatty acids, specifically eicosapentaenoic acid (EPA), prevents ventricular tachyarrhythmias (VT) with ischemic heart disease, but the underlying mechanisms still remain unclear. Thus, we examined the relation between the serum EPA/arachidonic acid (AA) ratio and electrophysiological properties in patients with ischemic heart disease. The study subjects consisted of 57 patients (46 males, mean age, 66 ± 13 years) with ischemic heart disease. T-wave alternans (TWA) and heart rate variability were assessed by 24hour Holter ECG, and left ventricular ejection fraction (LVEF) was determined by echocardiography. Fasting blood samples were collected, and the serum EPA/AA ratio was determined. Based on a median value of the serum EPA/AA ratio, all subjects were divided into two groups: serum EPA/AA ratio below 0.33 (Group-L, n = 28) or not (Group-H, n = 29). We compared these parameters between the two groups. LVEF was not different between the two groups. The maximum value of TWA was significantly higher in Group-L than in Group-H (69.5 ± 22.8 μV versus 48.7 ± 12.0 μV, P = 0.007). In addition, VT defined as above 3 beats was observed in 7 cases (25%) in Group-L, but there were no cases of VT in Group-H (P = 0.004). However, low-frequency (LF) component, high-frequency (HF) component, LF to HF ratio, and standard deviation of all R-R intervals were not different between the two groups. These results suggest that a low EPA/AA ratio may induce cardiac electrical instability, but not autonomic nervous imbalance, associated with VT in patients with ischemic heart disease.

Air emissions from sour-gas processing plants and dairy-cattle reproduction in Alberta, Canada.

PubMed

Scott, H M; Soskolne, C L; Martin, S W; Shoukri, M M; Lissemore, K D; Coppock, R W; Guidotti, T L

2003-02-15

The dispersion of air pollutants from all 231 licensed sour-gas processing plants in Alberta, Canada, was modeled on a monthly basis over a 10-year period (1985-1994). Exposure estimates for sulfur dioxide (SO(2)-used as a surrogate for exposure to combusted emissions) then were assigned to 1382 provincial dairy farms using a geographical-information system. Individual average and peak exposure for periods prior to each of 15 months of age and conception (four exposure-averaging periods for each of two dispersion models) were estimated for 163,988 primiparous female dairy-cattle between 1986 and 1994. Monthly or annual average farm-site exposure estimates likewise were assigned to associated herd-level data sets for the biologically relevant period of interest for each of three additional reproductive outcomes: monthly herd-average calving interval, stillbirth risk, and twinning risk. In one of the main-effects models, the maximum (i.e., peak) monthly sour-gas exposure experienced by individual-animals from birth to conception was associated with an increased time to first-calving in the very-highest exposure category (hazard ratio=0.86, 95% CI=0.80, 0.92). This equates to a decreased hazard (lambda) of calving (in each month subsequent to 22 months of age) for the highest-exposure animals (lambda=0.170) versus the zero-exposure animals (lambda=0.198) in a model with referent values for agro-ecological region and season of birth. The dose-response was not consistent across the full range of exposure categories. There was significant (P=0.003) interaction of emissions with agro-ecological region. After accounting for the interaction, a more-consistent dose-response was evident for some (but not all) agro-ecological regions. This suggests that any effect of emissions on dairy-heifer reproduction is subject to modification by features of soil type, vegetative cover, and/or climate. The increase in monthly herd-average calving interval on farms exposed to the very-highest levels of emissions appeared quite small and of limited practical importance within the range of expected exposures. There was no association between exposure and the risk for twinning. Herds exposed to higher emissions exhibited a slight decrease in risk for stillbirth.

Spatiotemporal distributions of ambient oxides of nitrogen, with implications for exposure inequality and urban design.

PubMed

Yu, Haofei; Stuart, Amy L

2013-08-01

Intra-urban differences in concentrations of oxides of nitrogen (NO(x)) and exposure disparities in the Tampa area were investigated across temporal scales through emissions estimation, dispersion modeling, and analysis of residential subpopulation exposures. A hybrid estimation method was applied to provide link-level hourly on-road mobile source emissions. Ambient concentrations in 2002 at 1 km resolution were estimated using the CALPUFF dispersion model. Results were combined with residential demographic data at the block-group level, to investigate exposures and inequality for select racioethnic, age, and income population subgroups. Results indicate that on-road mobile sources contributed disproportionately to ground-level concentrations and dominated the spatial footprint across temporal scales (annual average to maximum hour). The black, lower income (less than $40K annually), and Hispanic subgroups had higher estimated exposures than the county average; the white and higher income (greater than $60K) subgroups had lower than average exposures. As annual average concentration increased, the disparity between groups generally increased. However for the highest 1-hr concentrations, reverse disparities were also found. Current studies of air pollution exposure inequality have not fully considered differences by time scale and are often limited in spatial resolution. The modeling methods and the results presented here can be used to improve understanding of potential impacts of urban growth form on health and to improve urban sustainability. Results suggest focusing urban design interventions on reducing on-road mobile source emissions in areas with high densities of minority and low income groups.

Smoke exposure at western wildfires.

Treesearch

Timothy E. Reinhardt; Roger D. Ottmar

2000-01-01

Smoke exposure measurements among firefighters at wildfires in the Western United States between 1992 and 1995 showed that altogether most exposures were not significant, between 3 and 5 percent of the shift-average exposures exceeded occupational exposure limits for carbon monoxide and respiratory irritants. Exposure to benzene and total suspended particulate was not...

A study of classroom acoustics and school teachers' noise exposure, voice load and speaking time during teaching, and the effects on vocal and mental fatigue development.

PubMed

Kristiansen, Jesper; Lund, Søren Peter; Persson, Roger; Shibuya, Hitomi; Nielsen, Per Møberg; Scholz, Matthias

2014-11-01

The study investigated the noise exposure in a group of Danish school teachers. The aims were to investigate if noise posed a risk of impairment of hearing and to study the association between classroom acoustical conditions, noise exposure, vocal symptoms, and cognitive fatigue. Background noise levels, vocal load and speaking time were measured on 35 teachers during actual classroom teaching. The classrooms were characterized acoustically by measurements of reverberation time. Before and after the workday, the teachers answered a questionnaire on fatigue symptoms and carried out two cognitive test tasks sensitive to mental fatigue. The average noise level during the lessons was 72 dB(A), but during indoor sports activities the average noise level increased 6.6 dB(A). Room reverberation time (range 0.39-0.83 s) had no significant effect on the noise level. The teachers were talking with a raised voice in 61% of the time, and the vocal load increased 0.65 dB(A) per dB(A) increase in the average lesson noise level. An increase in voice symptoms during the workday correlated significantly with individual average noise exposure, and a decrease in performance in the two-back test correlated significantly with individual average vocal load. Noise exposure in general classrooms posed no risk of noise-induced hearing impairment in school teachers. However, the results provide evidence for an association between noise exposure and vocal load and development of vocal symptoms and cognitive fatigue after work.

Instrumental Variable Analysis with a Nonlinear Exposure–Outcome Relationship

PubMed Central

Davies, Neil M.; Thompson, Simon G.

2014-01-01

Background: Instrumental variable methods can estimate the causal effect of an exposure on an outcome using observational data. Many instrumental variable methods assume that the exposure–outcome relation is linear, but in practice this assumption is often in doubt, or perhaps the shape of the relation is a target for investigation. We investigate this issue in the context of Mendelian randomization, the use of genetic variants as instrumental variables. Methods: Using simulations, we demonstrate the performance of a simple linear instrumental variable method when the true shape of the exposure–outcome relation is not linear. We also present a novel method for estimating the effect of the exposure on the outcome within strata of the exposure distribution. This enables the estimation of localized average causal effects within quantile groups of the exposure or as a continuous function of the exposure using a sliding window approach. Results: Our simulations suggest that linear instrumental variable estimates approximate a population-averaged causal effect. This is the average difference in the outcome if the exposure for every individual in the population is increased by a fixed amount. Estimates of localized average causal effects reveal the shape of the exposure–outcome relation for a variety of models. These methods are used to investigate the relations between body mass index and a range of cardiovascular risk factors. Conclusions: Nonlinear exposure–outcome relations should not be a barrier to instrumental variable analyses. When the exposure–outcome relation is not linear, either a population-averaged causal effect or the shape of the exposure–outcome relation can be estimated. PMID:25166881

Assessment of exposures and potential risks to the US adult population from wear (attrition and abrasion) of gold and ceramic dental restorations.

PubMed

Richardson, G Mark; Clemow, Scott R; Peters, Rachel E; James, Kyle J; Siciliano, Steven D

2016-01-01

Little has been published on the chemical exposures and risks of dental restorative materials other than from dental amalgam and composite resins. Here we provide the first exposure and risk assessment for gold (Au) alloy and ceramic restorative materials. Based on the 2001-2004 US National Health and Nutrition Examination Survey (NHANES), we assessed the exposure of US adults to the components of Au alloy and ceramic dental restorations owing to dental material wear. Silver (Ag) is the most problematic component of Au alloy restorations, owing to a combination of toxicity and proportional composition. It was estimated that adults could possess an average of four tooth surfaces restored with Au alloy before exceeding, on average, the reference exposure level (REL) for Ag. Lithium (Li) is the most problematic component of dental ceramics. It was estimated that adults could possess an average of 15 tooth surfaces restored with ceramics before exceeding the REL for Li. Relative risks of chemical exposures from dental materials decrease in the following order: Amalgam>Au alloys>ceramics>composite resins.

Contribution of the in-vehicle microenvironment to individual ambient-source nitrogen dioxide exposure: the Multi-Ethnic Study of Atherosclerosis and Air Pollution.

PubMed

Hazlehurst, Marnie F; Spalt, Elizabeth W; Nicholas, Tyler P; Curl, Cynthia L; Davey, Mark E; Burke, Gregory L; Watson, Karol E; Vedal, Sverre; Kaufman, Joel D

2018-06-01

Exposure estimates that do not account for time in-transit may underestimate exposure to traffic-related air pollution, but exact contributions have not been studied directly. We conducted a 2-week monitoring, including novel in-vehicle sampling, in a subset of the Multi-Ethnic Study of Atherosclerosis and Air Pollution cohort in two cities. Participants spent the majority of their time indoors and only 4.4% of their time (63 min/day) in-vehicle, on average. The mean ambient-source NO 2 concentration was 5.1 ppb indoors and 32.3 ppb in-vehicle during drives. On average, indoor exposure contributed 69% and in-vehicle exposure contributed 24% of participants' ambient-source NO 2 exposure. For participants in the highest quartile of time in-vehicle (≥1.3 h/day), indoor and in-vehicle contributions were 60 and 31%, respectively. Incorporating infiltrated indoor and measured in-vehicle NO 2 produced exposure estimates 5.6 ppb lower, on average, than using only outdoor concentrations. The indoor microenvironment accounted for the largest proportion of ambient-source exposure in this older population, despite higher concentrations of NO 2 outdoors and in vehicles than indoors. In-vehicle exposure was more influential among participants who drove the most and for participants residing in areas with lower outdoor air pollution. Failure to characterize exposures in these microenvironments may contribute to exposure misclassification in epidemiologic studies.

Health effects of gasoline exposure. I. Exposure assessment for U.S. distribution workers.

PubMed Central

Smith, T J; Hammond, S K; Wong, O

1993-01-01

Personal exposures were estimated for a large cohort of workers in the U.S. domestic system for distributing gasoline by trucks and marine vessels. This assessment included development of a rationale and methodology for extrapolating vapor exposures prior to the availability of measurement data, analysis of existing measurement data to estimate task and job exposures during 1975-1985, and extrapolation of truck and marine job exposures before 1975. A worker's vapor exposure was extrapolated from three sets of factors: the tasks in his or her job associated with vapor sources, the characteristics of vapor sources (equipment and other facilities) at the work site, and the composition of petroleum products producing vapors. Historical data were collected on the tasks in job definitions, on work-site facilities, and on product composition. These data were used in a model to estimate the overall time-weighted-average vapor exposure for jobs based on estimates of task exposures and their duration. Task exposures were highest during tank filling in trucks and marine vessels. Measured average annual, full-shift exposures during 1975-1985 ranged from 9 to 14 ppm of total hydrocarbon vapor for truck drivers and 2 to 35 ppm for marine workers on inland waterways. Extrapolated past average exposures in truck operations were highest for truck drivers before 1965 (range 140-220 ppm). Other jobs in truck operations resulted in much lower exposures. Because there were few changes in marine operations before 1979, exposures were assumed to be the same as those measured during 1975-1985. Well-defined exposure gradients were found across jobs within time periods, which were suitable for epidemiologic analyses. PMID:8020436

Personal exposures to PM 2.5 and their relationships with microenvironmental concentrations

NASA Astrophysics Data System (ADS)

Lim, Soogil; Kim, Jeonghoon; Kim, Taehyun; Lee, Kiyoung; Yang, Wonho; Jun, Sangil; Yu, Seungdo

2012-02-01

Personal exposure to particulate matter of aerodynamic diameters less than 2.5 μm (PM 2.5) can be affected by various factors. The purpose of this study was to determine the impact of activity pattern and the contribution of each microenvironment to personal PM 2.5 exposure. Technicians carried a nephelometer for PM 2.5 while engaging in scripted time location activities. The scripted activities of 10 different population groups were based on time activity patterns of the Seoul population in Korea. A total of 58 daily PM 2.5 personal exposures were available for analysis. The average PM 2.5 personal exposure was 19.8 ± 15.3 μg m -3. The average personal exposure of each population group ranged from 9.8 to 43.1 μg m -3. High peak and average concentrations were observed in restaurants and bars; such high concentrations were due to secondhand smoke and cooking with charcoal on tables. The residential indoor level of the nine microenvironments was the largest contributor to personal exposure. The contributions from residential indoor, non-residential indoor, transportation, and outdoor levels were 36.2%, 53.4%, 6.7%, and 3.7%, respectively. The contributions of microenvironments varied among population groups; these variations suggest that the impact of activity pattern on personal exposure is significant.

Comparison of average global exposure of population induced by a macro 3G network in different geographical areas in France and Serbia.

PubMed

Huang, Yuanyuan; Varsier, Nadège; Niksic, Stevan; Kocan, Enis; Pejanovic-Djurisic, Milica; Popovic, Milica; Koprivica, Mladen; Neskovic, Aleksandar; Milinkovic, Jelena; Gati, Azeddine; Person, Christian; Wiart, Joe

2016-09-01

This article is the first thorough study of average population exposure to third generation network (3G)-induced electromagnetic fields (EMFs), from both uplink and downlink radio emissions in different countries, geographical areas, and for different wireless device usages. Indeed, previous publications in the framework of exposure to EMFs generally focused on individual exposure coming from either personal devices or base stations. Results, derived from device usage statistics collected in France and Serbia, show a strong heterogeneity of exposure, both in time, that is, the traffic distribution over 24 h was found highly variable, and space, that is, the exposure to 3G networks in France was found to be roughly two times higher than in Serbia. Such heterogeneity is further explained based on real data and network architecture. Among those results, authors show that, contrary to popular belief, exposure to 3G EMFs is dominated by uplink radio emissions, resulting from voice and data traffic, and average population EMF exposure differs from one geographical area to another, as well as from one country to another, due to the different cellular network architectures and variability of mobile usage. Bioelectromagnetics. 37:382-390, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Occupational exposure to electric fields and induced currents associated with 400 kV substation tasks from different service platforms.

PubMed

Korpinen, Leena H; Elovaara, Jarmo A; Kuisti, Harri A

2011-01-01

The aim of the study was to investigate the occupational exposure to electric fields, average current densities, and average total contact currents at 400 kV substation tasks from different service platforms (main transformer inspection, maintenance of operating device of disconnector, maintenance of operating device of circuit breaker). The average values are calculated over measured periods (about 2.5 min). In many work tasks, the maximum electric field strengths exceeded the action values proposed in the EU Directive 2004/40/EC, but the average electric fields (0.2-24.5 kV/m) were at least 40% lower than the maximum values. The average current densities were 0.1-2.3 mA/m² and the average total contact currents 2.0-143.2 µA, that is, clearly less than the limit values of the EU Directive. The average values of the currents in head and contact currents were 16-68% lower than the maximum values when we compared the average value from all cases in the same substation. In the future it is important to pay attention to the fact that the action and limit values of the EU Directive differ significantly. It is also important to take into account that generally, the workers' exposure to the electric fields, current densities, and total contact currents are obviously lower if we use the average values from a certain measured time period (e.g., 2.5 min) than in the case where exposure is defined with only the help of the maximum values. © 2010 Wiley-Liss, Inc.

Investigation of Electromagnetic Field Threat to Fuel Tank Wiring of a Transport Aircraft

NASA Technical Reports Server (NTRS)

Ely, Jay J.; Nguyen, Truong X.; Dudley, Kenneth L.; Scearce, Stephen A.; Beck, Fred B.; Deshpande, Manohar D.; Cockrell, C. R.

2000-01-01

National Transportation Safety Board investigators have questioned whether an electrical discharge in the Fuel Quantity Indication System (FQIS) may have initiated the TWA-800 center wing tank explosion. Because the FQIS was designed to be incapable of producing such a discharge on its own, attention has been directed to mechanisms of outside electromagnetic influence. To support the investigation, the NASA Langley Research Center was tasked to study the potential for radiated electromagnetic fields from external radio frequency (RF) transmitters and passenger carried portable electronic devices (PEDs) to excite the FQIS enough to cause arcing, sparking or excessive heating within the fuel tank.

Protons from carbon ion fragmentation at 0.3–2.0 GeV/nucleon: Comparison with models of ion-ion interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abramov, B. M.; Alekseev, P. N.; Borodin, Yu. A.

2015-05-15

Yields of protons at 3.5° from carbon ion fragmentation at energies of T{sub 0} = 0.3, 0.6, 0.95, and 2.0 GeV/nucleon on a Be target were measured in the FRAGM experiment at TWA-ITEP heavy-ion facility. Proton momentum spectra cover both the region of the fragmentation maximum and the cumulative region. The differential cross sections span six orders of its magnitude. The spectra are compared with the predictions of four models of ion-ion interactions: LAQGSM03.03, SHIELD-HIT, QMD, and BC.

Time Averaged Transmitter Power and Exposure to Electromagnetic Fields from Mobile Phone Base Stations

PubMed Central

Bürgi, Alfred; Scanferla, Damiano; Lehmann, Hugo

2014-01-01

Models for exposure assessment of high frequency electromagnetic fields from mobile phone base stations need the technical data of the base stations as input. One of these parameters, the Equivalent Radiated Power (ERP), is a time-varying quantity, depending on communication traffic. In order to determine temporal averages of the exposure, corresponding averages of the ERP have to be available. These can be determined as duty factors, the ratios of the time-averaged power to the maximum output power according to the transmitter setting. We determine duty factors for UMTS from the data of 37 base stations in the Swisscom network. The UMTS base stations sample contains sites from different regions of Switzerland and also different site types (rural/suburban/urban/hotspot). Averaged over all regions and site types, a UMTS duty factor F ≈ 0.32 ± 0.08 for the 24 h-average is obtained, i.e., the average output power corresponds to about a third of the maximum power. We also give duty factors for GSM based on simple approximations and a lower limit for LTE estimated from the base load on the signalling channels. PMID:25105551

Ultrafine particle concentrations and exposures in seven residences in northern California.

PubMed

Bhangar, S; Mullen, N A; Hering, S V; Kreisberg, N M; Nazaroff, W W

2011-04-01

Human exposures to ultrafine particles (UFP) are poorly characterized given the potential associated health risks. Residences are important sites of exposure. To characterize residential exposures to UFP in some circumstances and to investigate governing factors, seven single-family houses in California were studied during 2007-2009. During multiday periods, time-resolved particle number concentrations were monitored indoors and outdoors and information was acquired concerning occupancy, source-related activities, and building operation. On average, occupants were home for 70% of their time. The geometric mean time-average residential exposure concentration for 21 study subjects was 14,500 particles per cm(3) (GSD = 1.8; arithmetic mean ± standard deviation = 17,000 ± 10,300 particles per cm(3)). The average contribution to residential exposures from indoor episodic sources was 150% of the contribution from particles of outdoor origin. Unvented natural-gas pilot lights contributed up to 19% to exposure for the two households where present. Episodic indoor source activities, most notably cooking, caused the highest peak exposures and most of the variation in exposure among houses. Owing to the importance of indoor sources and variations in the infiltration factor, residential exposure to UFP cannot be characterized by ambient measurements alone. Indoor and outdoor sources each contribute to residential ultrafine particle (UFP) concentrations and exposures. Under the conditions investigated, peak exposure concentrations indoors were associated with cooking, using candles, or the use of a furnace. Active particle removal systems can mitigate exposure by reducing the persistence of particles indoors. Eliminating the use of unvented gas pilot lights on cooking appliances could also be beneficial. The study results indicate that characterization of human exposure to UFP, an air pollutant of emerging public health concern, cannot be accomplished without a good understanding of conditions inside residences. © 2010 John Wiley & Sons A/S.

Evaluation of Background Exposures of Americans to Dioxin-Like Compounds in the 1990's and the 2000's

USDA-ARS?s Scientific Manuscript database

The US Environmental Protection Agency’s 2004 Dioxin Reassessment included a characterization of background exposures to dioxin-like compounds, including an estimate of an average background intake dose and an average background body burden. These quantities were derived from data generated in the m...

Pesticides from wastewater treatment plant effluents affect invertebrate communities.

PubMed

Münze, Ronald; Hannemann, Christin; Orlinskiy, Polina; Gunold, Roman; Paschke, Albrecht; Foit, Kaarina; Becker, Jeremias; Kaske, Oliver; Paulsson, Elin; Peterson, Märit; Jernstedt, Henrik; Kreuger, Jenny; Schüürmann, Gerrit; Liess, Matthias

2017-12-01

We quantified pesticide contamination and its ecological impact up- and downstream of seven wastewater treatment plants (WWTPs) in rural and suburban areas of central Germany. During two sampling campaigns, time-weighted average pesticide concentrations (c TWA ) were obtained using Chemcatcher® passive samplers; pesticide peak concentrations were quantified with event-driven samplers. At downstream sites, receiving waters were additionally grab sampled for five selected pharmaceuticals. Ecological effects on macroinvertebrate structure and ecosystem function were assessed using the biological indicator system SPEAR pesticides (SPEcies At Risk) and leaf litter breakdown rates, respectively. WWTP effluents substantially increased insecticide and fungicide concentrations in receiving waters; in many cases, treated wastewater was the exclusive source for the neonicotinoid insecticides acetamiprid and imidacloprid in the investigated streams. During the ten weeks of the investigation, five out of the seven WWTPs increased in-stream pesticide toxicity by a factor of three. As a consequence, at downstream sites, SPEAR values and leaf litter degradation rates were reduced by 40% and 53%, respectively. The reduced leaf litter breakdown was related to changes in the macroinvertebrate communities described by SPEAR pesticides and not to altered microbial activity. Neonicotinoids showed the highest ecological relevance for the composition of invertebrate communities, occasionally exceeding the Regulatory Acceptable Concentrations (RACs). In general, considerable ecological effects of insecticides were observed above and below regulatory thresholds. Fungicides, herbicides and pharmaceuticals contributed only marginally to acute toxicity. We conclude that pesticide retention of WWTPs needs to be improved. Copyright © 2017 Elsevier B.V. All rights reserved.

Monitoring tylosin and sulfamethazine in a tile-drained agricultural watershed using polar organic chemical integrative sampler (POCIS).

PubMed

Washington, Maurice T; Moorman, Thomas B; Soupir, Michelle L; Shelley, Mack; Morrow, Amy J

2018-01-15

This study evaluated the influence of temporal variation on the occurrence, fate, and transport of tylosin (TYL) and sulfamethazine (SMZ); antibiotics commonly used in swine production. Atrazine (ATZ) was used as a reference analyte to indicate the agricultural origin of the antibiotics. We also assessed the impact of season and hydrology on antibiotic concentrations. A reconnaissance study of the South Fork watershed of the Iowa River (SFIR), was conducted from 2013 to 2015. Tile drain effluent and surface water were monitored using polar organic integrative sampler (POCIS) technology. Approximately 169 animal feeding operations (AFOs) exist in SFIR, with 153 of them being swine facilities. All analytes were detected, and detection frequencies ranged from 69 to 100% showing the persistence in the watershed. Antibiotics were detected at a higher frequency using POCIS compared to grab samples. We observed statistically significant seasonal trends for SMZ and ATZ concentrations during growing and harvest seasons. Time weighted average (TWA) concentrations quantified from the POCIS were 1.87ngL -1 (SMZ), 0.30ngL -1 (TYL), and 754.2ngL -1 (ATZ) in the watershed. SMZ and TYL concentrations were lower than the minimum inhibitory concentrations (MIC) for E. coli. All analytes were detected in tile drain effluent, confirming tile drainage as a pathway for antibiotic transport. Our results identify the episodic occurrence of antibiotics, and highlights the importance identifying seasonal fate and occurrence of these analytes. Published by Elsevier B.V.

Extension of Oxygen Tolerance in Man. Predictive Studies 6.

DTIC Science & Technology

1991-12-31

maintained on Ziegler rat and mouse diet were used in these -12- i exposures. Average weights of the different exposure groups ranged from about 300...end of oxygen exposure were associated with reciprocal changes in end-tidal PCO 2 . Average PCO 2 (N=7) decreased significantly from 40.8 mm Hg during... PCO 2 (N=6) increased from 30.8 to 36.2 mm Hg. An increased frequency of breathing with a related reduction in tidal volume was found near the end of

Modeling Of In-Vehicle Human Exposure to Ambient Fine Particulate Matter

PubMed Central

Liu, Xiaozhen; Frey, H. Christopher

2012-01-01

A method for estimating in-vehicle PM2.5 exposure as part of a scenario-based population simulation model is developed and assessed. In existing models, such as the Stochastic Exposure and Dose Simulation model for Particulate Matter (SHEDS-PM), in-vehicle exposure is estimated using linear regression based on area-wide ambient PM2.5 concentration. An alternative modeling approach is explored based on estimation of near-road PM2.5 concentration and an in-vehicle mass balance. Near-road PM2.5 concentration is estimated using a dispersion model and fixed site monitor (FSM) data. In-vehicle concentration is estimated based on air exchange rate and filter efficiency. In-vehicle concentration varies with road type, traffic flow, windspeed, stability class, and ventilation. Average in-vehicle exposure is estimated to contribute 10 to 20 percent of average daily exposure. The contribution of in-vehicle exposure to total daily exposure can be higher for some individuals. Recommendations are made for updating exposure models and implementation of the alternative approach. PMID:23101000

Survey of residential 50 Hz EMF exposure from transformer stations.

PubMed

Szabó, Judit; Jánossy, Gábor; Thuróczy, György

2007-01-01

In Hungary it is typical that 10/04 kV transformer stations are being installed in multistory residential and office buildings. Magnetic fields (MFs) up to several tens of microT have been measured in apartments close to transformers. The aim of the present study was to provide systematic assessment of MF exposure of residents living above transformer stations. Out of 41 addresses provided by the electricity supplier, current load of 21 transformers and MF in 21 apartments was measured. Spot MFs at 1 m height and time weighted average 24 h MF exposure at bed height was measured. All-day personal MF exposure was measured at waist and HOME exposure was calculated. BED exposure was measured at bed height. Participants kept a time-activity diary. The time-weighted average 24 h MF exposure (3.03 microT) exceeded the usual residential exposure (<0.2 microT). The mean HOME and BED personal exposure above transformers was 0.825 and 1.033 microT, respectively. Our study provides exposure assessment of a cohort with a wider exposure range, compared to power-line epidemiological studies.

FACTORS EFFECTING EXPOSURES TO VOCS DURING COMMUTING IN CALIFORNIA

EPA Science Inventory

On the average, Californian's spend between one and three hours each day commuting. The contribution from in-vehicle exposures to air toxics may be a significant component of total air exposure. Although pollutant concentration data are important for exposure assessments, onl...

Use of real-time sensors to characterise human exposures to combustion related pollutants.

PubMed

Delgado-Saborit, Juana Maria

2012-07-01

Concentrations of black carbon and nitrogen dioxide have been collected concurrently using a MicrAeth AE-51 and an Aeroqual GSS NO(2) sensor. Forty five sampling events with a duration spanning between 16 and 22 hours have collected 10,800 5 min data in Birmingham (UK) from July to October 2011. The high temporal resolution database allowed identification of peak exposures and which activities contributed the most to these peaks, such as cooking and commuting. Personal exposure concentrations for non-occupationally exposed subjects ranged between 0.01 and 50 μg m(-3) for BC with average values of 1.3 ± 2.2 μg m(-3) (AM ± SD). Nitrogen dioxide exposure concentrations were in the range

Inhalation Exposures to Particulate Matter and Carbon Monoxide during Ethiopian Coffee Ceremonies in Addis Ababa: A Pilot Study

PubMed Central

Keil, Chris; Kassa, Hailu; Brown, Alexander; Kumie, Abera; Tefera, Worku

2010-01-01

The unique Ethiopian cultural tradition of the coffee ceremony increases inhalation exposures to combustion byproducts. This pilot study evaluated exposures to particulate matter and carbon monoxide in ten Addis Ababa homes during coffee ceremonies. For coffee preparers the geometric mean (57 μg/m3) and median (72 μg/m3) contributions to an increase in a 24-hour time-weighted average exposure were above World Health Organization (WHO) guidelines. At 40% of the study sites the contribution to the 24-hour average exposure was greater than twice the WHO guideline. Similar exposure increases existed for ceremony participants. Particulate matter concentrations may be related to the use of incense during the ceremony. In nearly all homes the WHO guideline for a 60-minute exposure to carbon monoxide was exceeded. Finding control measures to reduce these exposures will be challenging due to the deeply engrained nature of this cultural practice and the lack of availability of alternative fuels. PMID:20886061

Inhalation exposures to particulate matter and carbon monoxide during Ethiopian coffee ceremonies in Addis Ababa: a pilot study.

PubMed

Keil, Chris; Kassa, Hailu; Brown, Alexander; Kumie, Abera; Tefera, Worku

2010-01-01

The unique Ethiopian cultural tradition of the coffee ceremony increases inhalation exposures to combustion byproducts. This pilot study evaluated exposures to particulate matter and carbon monoxide in ten Addis Ababa homes during coffee ceremonies. For coffee preparers the geometric mean (57 μg/m³) and median (72 μg/m³) contributions to an increase in a 24-hour time-weighted average exposure were above World Health Organization (WHO) guidelines. At 40% of the study sites the contribution to the 24-hour average exposure was greater than twice the WHO guideline. Similar exposure increases existed for ceremony participants. Particulate matter concentrations may be related to the use of incense during the ceremony. In nearly all homes the WHO guideline for a 60-minute exposure to carbon monoxide was exceeded. Finding control measures to reduce these exposures will be challenging due to the deeply engrained nature of this cultural practice and the lack of availability of alternative fuels.

Personal carbon monoxide exposure in Helsinki, Finland

NASA Astrophysics Data System (ADS)

Scotto di Marco, Greta; Kephalopoulos, Stylianos; Ruuskanen, Juhani; Jantunen, Matti

Personal exposure concentrations of carbon monoxide (CO) were measured for the adult urban population of Helsinki, Finland, as part of the multi-centre European EXPOLIS study. The arithmetic mean of the 48 h average personal CO exposure concentration was 1.3 mg m -3 for participants not exposed to environmental tobacco smoke (ETS) and 1.6 mg m -3 for those exposed to ETS at any time and in any microenvironment. The maximum 8 and 1 h exposure values were 2.0 and 2.6 mg m -3, and 4.3 and 5.7 mg m -3, respectively. As tobacco smoke is one of the major sources of CO, therefore the personal mean exposures of ETS participants were higher than the non-ETS participants for all averaging times. The long- and short-term personal exposures were higher in winter than in summer for all participants. In order to analyse in more detail the correlation between the time-activity patterns and exposure levels, cluster analysis was performed using 24 h personal exposure profiles of 1 h moving averages. The results showed clearly that the major source of CO for non-ETS exposed participants are traffic emissions. The majority of the diurnal exposure profiles showed two notable exposure peaks corresponding to the morning and evening traffic rush hours. The time spent in street traffic was the most relevant factor for describing the short-term personal exposures. The more time was spent commuting by car the higher were the exposures. The long-term exposure levels were linked both to the time spent commuting and home location. People living in low-traffic suburban areas and working in downtown spent more time commuting and ended up experiencing similar long-term exposure levels than people who lived in heavy-traffic downtown areas, but spent little time commuting. For ETS exposed participants the personal exposure profiles were dominated by both tobacco smoke and traffic emissions.

Trends in Occupational Exposure to Styrene in the European Glass Fibre-Reinforced Plastics Industry

PubMed Central

Van Rooij, J. G. M.; Kasper, A.; Triebig, G.; Werner, P.; Kromhout, H.

2008-01-01

Aim: This study presents temporal trends of styrene exposure for workers in the European glass fibre-reinforced plastics (GRP) industry during the period 1966–2002. Methods: Data of personal styrene exposure measurements were retrieved from reports, databases and peer-reviewed papers. Only sources with descriptive statistics of personal measurements were accepted. The styrene exposure data cover personal air samples and biological monitoring data, that is, urinary styrene metabolites (mandelic acid and/or phenylglyoxylic acid) and styrene in blood. Means of series of measurements were categorized by year, country, production process, job and sampling strategy. Linear mixed models were used to identify temporal trends and factors affecting exposure levels. Results: Personal exposure measurements were available from 60 reports providing data on 24145 1–8-h time-weighted average shift personal air samples. Available data of biological exposure indicators included measurements of mandelic acid in post-shift urine (6361 urine samples being analysed). Trend analyses of the available styrene exposure data showed that the average styrene concentration in the breathing zone of open-mould workers in the European GRP industry has decreased on average by 5.3% per year during the period 1966–1990 and by only 0.4% annually in the period after 1990. The highest exposures were measured in Southern Europe and the lowest exposures in Northern Europe with Central Europe in between. Biological indicators of styrene (mandelic acid in post-shift urine) showed a somewhat steeper decline (8.9%), most likely because urine samples were collected in companies that showed a stronger decrease of styrene exposure in air than GRP companies where no biological measurements were carried out. PMID:18550625

Time-dependent effect of intensity of smoking and of occupational exposure to asbestos on the risk of lung cancer: results from the ICARE case-control study.

PubMed

Lévêque, Emilie; Lacourt, Aude; Luce, Danièle; Sylvestre, Marie-Pierre; Guénel, Pascal; Stücker, Isabelle; Leffondré, Karen

2018-05-18

To estimate the impact of intensity of both smoking and occupational exposure to asbestos on the risk of lung cancer throughout the whole exposure history. Data on 2026 male cases and 2610 male controls came from the French ICARE (Investigation of occupational and environmental causes of respiratory cancers) population-based, case-control study. Lifetime smoking history and occupational history were collected from standardised questionnaires and face-to-face interviews. Occupational exposure to asbestos was assessed using a job exposure matrix. The effects of annual average daily intensity of smoking (reported average number of cigarettes smoked per day) and asbestos exposure (estimated average daily air concentration of asbestos fibres at work) were estimated using a flexible weighted cumulative index of exposure in logistic regression models. Intensity of smoking in the 10 years preceding diagnosis had a much stronger association with the risk of lung cancer than more distant intensity. By contrast, intensity of asbestos exposure that occurred more than 40 years before diagnosis had a stronger association with the risk of lung cancer than more recent intensity, even if intensity in the 10 years preceding diagnosis also had a significant effect. Our results illustrate the dynamic of the effect of intensity of both smoking and occupational exposure to asbestos on the risk of lung cancer. They confirm that the timing of exposure plays an important role, and suggest that standard analytical methods assuming equal weights of intensity over the whole exposure history may be questionable. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Long-Term PM2.5 Exposure and Respiratory, Cancer, and Cardiovascular Mortality in Older US Adults.

PubMed

Pun, Vivian C; Kazemiparkouhi, Fatemeh; Manjourides, Justin; Suh, Helen H

2017-10-15

The impact of chronic exposure to fine particulate matter (particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5)) on respiratory disease and lung cancer mortality is poorly understood. In a cohort of 18.9 million Medicare beneficiaries (4.2 million deaths) living across the conterminous United States between 2000 and 2008, we examined the association between chronic PM2.5 exposure and cause-specific mortality. We evaluated confounding through adjustment for neighborhood behavioral covariates and decomposition of PM2.5 into 2 spatiotemporal scales. We found significantly positive associations of 12-month moving average PM2.5 exposures (per 10-μg/m3 increase) with respiratory, chronic obstructive pulmonary disease, and pneumonia mortality, with risk ratios ranging from 1.10 to 1.24. We also found significant PM2.5-associated elevated risks for cardiovascular and lung cancer mortality. Risk ratios generally increased with longer moving averages; for example, an elevation in 60-month moving average PM2.5 exposures was linked to 1.33 times the lung cancer mortality risk (95% confidence interval: 1.24, 1.40), as compared with 1.13 (95% confidence interval: 1.11, 1.15) for 12-month moving average exposures. Observed associations were robust in multivariable models, although evidence of unmeasured confounding remained. In this large cohort of US elderly, we provide important new evidence that long-term PM2.5 exposure is significantly related to increased mortality from respiratory disease, lung cancer, and cardiovascular disease. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Auditory Exposure in the Neonatal Intensive Care Unit: Room Type and Other Predictors.

PubMed

Pineda, Roberta; Durant, Polly; Mathur, Amit; Inder, Terrie; Wallendorf, Michael; Schlaggar, Bradley L

2017-04-01

To quantify early auditory exposures in the neonatal intensive care unit (NICU) and evaluate how these are related to medical and environmental factors. We hypothesized that there would be less auditory exposure in the NICU private room, compared with the open ward. Preterm infants born at ≤ 28 weeks gestation (33 in the open ward, 25 in private rooms) had auditory exposure quantified at birth, 30 and 34 weeks postmenstrual age (PMA), and term equivalent age using the Language Environmental Acquisition device. Meaningful language (P < .0001), the number of adult words (P < .0001), and electronic noise (P < .0001) increased across PMA. Silence increased (P = .0007) and noise decreased (P < .0001) across PMA. There was more silence in the private room (P = .02) than the open ward, with an average of 1.9 hours more silence in a 16-hour period. There was an interaction between PMA and room type for distant words (P = .01) and average decibels (P = .04), indicating that changes in auditory exposure across PMA were different for infants in private rooms compared with infants in the open ward. Medical interventions were related to more noise in the environment, although parent presence (P = .009) and engagement (P  = .002) were related to greater language exposure. Average sound levels in the NICU were 58.9 ± 3.6 decibels, with an average peak level of 86.9 ± 1.4 decibels. Understanding the NICU auditory environment paves the way for interventions that reduce high levels of adverse sound and enhance positive forms of auditory exposure, such as language. Copyright © 2016 Elsevier Inc. All rights reserved.

Asbestos exposure from the overhaul of a Pratt & Whitney R2800 engine.

PubMed

Mlynarek, S P; Van Orden, D R

2012-11-01

This study assessed the asbestos exposures of airplane piston engine mechanics while performing overhaul work on a Pratt & Whitney R2800 radial engine, with tools and practices in use since the time these engines were manufactured. Approximately 40% of the bulk samples collected during this test were found to contain chrysotile. Air samples were collected during the overhaul and were analyzed by phase contrast microscopy (PCM) and transmission electron microscopy (TEM). The average worker exposure during disassembly was 0.0272f/ml (PCM) and ranged from 0.0013 to 0.1240f/ml (PCM) during an average sample collection time of 188min. The average worker exposure during reassembly was 0.0198f/ml (PCM) and ranged from 0.0055 to 0.0913f/ml (PCM) during an average sample collection time of 222min. Only one worker sample (during reassembly) was found to contain asbestos at a concentration of 0.0012f/ml (PCME). Similar results should be found in other aircraft piston engines that use metal clad and non-friable asbestos gaskets, which are the current standard in aircraft piston engines. Copyright © 2012 Elsevier Inc. All rights reserved.

Preparation and performance features of wristband samplers and considerations for chemical exposure assessment

PubMed Central

Anderson, Kim A; Points, Gary L; Donald, Carey E; Dixon, Holly M; Scott, Richard P; Wilson, Glenn; Tidwell, Lane G; Hoffman, Peter D; Herbstman, Julie B; O'Connell, Steven G

2017-01-01

Wristbands are increasingly used for assessing personal chemical exposures. Unlike some exposure assessment tools, guidelines for wristbands, such as preparation, applicable chemicals, and transport and storage logistics, are lacking. We tested the wristband’s capacity to capture and retain 148 chemicals including polychlorinated biphenyls (PCBs), pesticides, flame retardants, polycyclic aromatic hydrocarbons (PAHs), and volatile organic chemicals (VOCs). The chemicals span a wide range of physical–chemical properties, with log octanol–air partitioning coefficients from 2.1 to 13.7. All chemicals were quantitatively and precisely recovered from initial exposures, averaging 102% recovery with relative SD ≤21%. In simulated transport conditions at +30 °C, SVOCs were stable up to 1 month (average: 104%) and VOC levels were unchanged (average: 99%) for 7 days. During long-term storage at −20 °C up to 3 (VOCs) or 6 months (SVOCs), all chemical levels were stable from chemical degradation or diffusional losses, averaging 110%. Applying a paired wristband/active sampler study with human participants, the first estimates of wristband–air partitioning coefficients for PAHs are presented to aid in environmental air concentration estimates. Extrapolation of these stability results to other chemicals within the same physical–chemical parameters is expected to yield similar results. As we better define wristband characteristics, wristbands can be better integrated in exposure science and epidemiological studies. PMID:28745305

Raman-based Oxygen and Nitrogen Sensor for Monitoring Empty Airplane Fuel Tanks

NASA Technical Reports Server (NTRS)

Chen, Peter C.

2004-01-01

The purpose of this project was to develop a Raman-based method for detecting oxygen and nitrogen in empty fuel tanks. The need for such a method comes from the potential danger of allowing explosive oxygen-fuel mixtures to accumulate in empty airplane fuel tanks. An explosion resulting from such a mixture is believed to have caused the Flight TWA 800 disaster in 1996. Recently, (e.g., February 17,2004 press release) the FAA announced its intentions to make fuel tank inerting mandatory. One potential solution to this problem is to use an inert gas such as nitrogen to flood the empty fue1 tanks in order to reduce the concentration of oxygen.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abramov, B. M.; Alexeev, P. N.; Borodin, Yu. A.

The yields of long-lived nuclear fragments at an angle of 3.5° that originate fromthe fragmentation of carbon ions with an energy of T{sub 0} = 0.6 GeV per nucleon on a berylliumtarget were measured in the FRAGMexperiment at the ITEP TWA heavy-ion accelerator. The momentum spectra of these fragments cover both the fragmentation-maximum region and the cumulative region. The respective differential cross sections change by about five orders of magnitude. The momentum distributions of fragments in the laboratory frame and their kinetic-energy distributions in the rest frame of the fragmenting nucleus are used to test the predictions of four modelsmore » of ion–ion interactions: BC, INCL++, LAQGSM03.03, and QMD.« less

Body heating induced by sub-resonant (350 MHz) microwave irradiation: cardiovascular and respiratory responses in anesthetized rats.

PubMed

Jauchem, J R; Frei, M R

1997-01-01

These experiments were designed to investigate the effects of sub-resonant microwave (MW) exposure (350 MHz, E orientation, average power density 38 mW/cm2, average whole-body specific absorption rate 13.2 W/kg) on selected physiological parameters. The increase in peripheral body temperature during 350 MHz exposure was greater than that in earlier experiments performed at 700 MHz (resonance). Heart rate and mean arterial blood pressure were significantly elevated during a 1 degree C increase in colonic temperature due to 350 MHz exposure; respiratory rate showed no significant change. The results are consistent with other investigators' reports comparing sub-resonance exposures with those at resonance and above.

Sequential Neighborhood Effects: The Effect of Long-Term Exposure to Concentrated Disadvantage on Children's Reading and Math Test Scores.

PubMed

Hicks, Andrew L; Handcock, Mark S; Sastry, Narayan; Pebley, Anne R

2018-02-01

Prior research has suggested that children living in a disadvantaged neighborhood have lower achievement test scores, but these studies typically have not estimated causal effects that account for neighborhood choice. Recent studies used propensity score methods to account for the endogeneity of neighborhood exposures, comparing disadvantaged and nondisadvantaged neighborhoods. We develop an alternative propensity function approach in which cumulative neighborhood effects are modeled as a continuous treatment variable. This approach offers several advantages. We use our approach to examine the cumulative effects of neighborhood disadvantage on reading and math test scores in Los Angeles. Our substantive results indicate that recency of exposure to disadvantaged neighborhoods may be more important than average exposure for children's test scores. We conclude that studies of child development should consider both average cumulative neighborhood exposure and the timing of this exposure.

Estimation of the diesel exhaust exposures of railroad workers: II. National and historical exposures.

PubMed

Woskie, S R; Smith, T J; Hammond, S K; Schenker, M B; Garshick, E; Speizer, F E

1988-01-01

The diesel exhaust exposures of railroad workers in thirteen job groups from four railroads in the United States were used to estimate U.S. national average exposures with a linear statistical model which accounts for the significant variability in exposure caused by climate, the differences among railroads and the uneven distribution of railroad workers across climatic regions. Personal measurements of respirable particulate matter, adjusted to remove the contribution of cigarette smoke particles, were used as a marker for diesel exhaust. The estimated national means of adjusted respirable particulate matter (ARP) averaged 10 micrograms/m3 lower than the simple means for each job group, reflecting the climatic differences between the northern railroads studied and the distribution of railroad workers nationally. Limited historical records, including some industrial hygiene data, were used to evaluate past diesel exhaust exposures, which were estimated to be approximately constant from the 1950's to 1983.

Sequential Neighborhood Effects: The Effect of Long-Term Exposure to Concentrated Disadvantage on Children's Reading and Math Test Scores

PubMed Central

Hicks, Andrew L.; Handcock, Mark S.; Sastry, Narayan

2018-01-01

Prior research has suggested that children living in a disadvantaged neighborhood have lower achievement test scores, but these studies typically have not estimated causal effects that account for neighborhood choice. Recent studies used propensity score methods to account for the endogeneity of neighborhood exposures, comparing disadvantaged and nondisadvantaged neighborhoods. We develop an alternative propensity function approach in which cumulative neighborhood effects are modeled as a continuous treatment variable. This approach offers several advantages. We use our approach to examine the cumulative effects of neighborhood disadvantage on reading and math test scores in Los Angeles. Our substantive results indicate that recency of exposure to disadvantaged neighborhoods may be more important than average exposure for children's test scores. We conclude that studies of child development should consider both average cumulative neighborhood exposure and the timing of this exposure. PMID:29192386

[The application of two occupation health risk assessment models in a wooden furniture manufacturing industry].

PubMed

Wang, A H; Leng, P B; Bian, G L; Li, X H; Mao, G C; Zhang, M B

2016-10-20

Objective: To explore the applicability of 2 different models of occupational health risk assessment in wooden furniture manufacturing industry. Methods: American EPA inhalation risk model and ICMM model of occupational health risk assessment were conducted to assess occupational health risk in a small wooden furniture enterprises, respectively. Results: There was poor protective measure and equipment of occupational disease in the plant. The concentration of wood dust in the air of two workshops was over occupational exposure limit (OEL) , and the C TWA was 8.9 mg/m 3 and 3.6 mg/m 3 , respectively. According to EPA model, the workers who exposed to benzene in this plant had high risk (9.7×10 -6 ~34.3×10 -6 ) of leukemia, and who exposed to formaldehyde had high risk (11.4 × 10 -6 ) of squamous cell carcinoma. There were inconsistent evaluation results using the ICMM tools of standard-based matrix and calculated risk rating. There were very high risks to be attacked by rhinocarcinoma of the workers who exposed to wood dust for the tool of calculated risk rating, while high risk for the tool of standard-based matrix. For the workers who exposed to noise, risk of noise-induced deafness was unacceptable and medium risk using two tools, respectively. Conclusion: Both EPA model and ICMM model can appropriately predict and assessthe occupational health risk in wooden furniture manufactory, ICMM due to the relatively simple operation, easy evaluation parameters, assessment of occupational - disease - inductive factors comprehensively, and more suitable for wooden furniture production enterprise.

Operation of the computer model for microenvironment atomic oxygen exposure

NASA Technical Reports Server (NTRS)

Bourassa, R. J.; Gillis, J. R.; Gruenbaum, P. E.

1995-01-01

A computer model for microenvironment atomic oxygen exposure has been developed to extend atomic oxygen modeling capability to include shadowing and reflections. The model uses average exposure conditions established by the direct exposure model and extends the application of these conditions to treat surfaces of arbitrary shape and orientation.

Indoor molds and lung function in healthy adults.

PubMed

Hernberg, Samu; Sripaiboonkij, Penpatra; Quansah, Reginald; Jaakkola, Jouni J K; Jaakkola, Maritta S

2014-05-01

Indoor mold exposure is common worldwide and constitutes an important health problem. There are very few studies assessing the relation between mold exposure and lung function levels among non-asthmatic adults. Our objective was to assess the relations between dampness and mold exposures at home and at work and lung function. In particular, we elaborated the importance of different exposure indicators. In a population-based study, 269 non-asthmatic adults from South Finland answered a questionnaire on indoor dampness and mold exposures at home or at work and other factors potentially influencing lung function, and performed spirometry. Multiple linear regression model was applied to study the relations between exposures and spirometric lung function levels. In linear regression adjusting for confounding, FEV1 level was reduced on average 200 ml related to mold odor at home (effect estimate -0.20, 95% CI -0.60 to 0.21) and FVC level was reduced on average 460 ml (-0.46, -0.95 to 0.03) respectively. Exposure to mold odor at home or at work or both was related to reduced FEV1 (-0.15, -0.42 to 0.12) and FVC (-0.22, -0.55 to 0.11) levels. Women had on average 510 ml reduced FEV1 levels (-0.51, -1.0 to 0.03) and 820 ml reduced FVC levels (-0.82, -1.4 to -0.20) related to mold odor exposure at home. Mold odor exposure was related to lower lung function levels among non-asthmatic adults, especially among women. Copyright © 2014 Elsevier Ltd. All rights reserved.

Monitoring of solar-UV exposure among schoolchildren in five Japanese cities using spore dosimeter and UV-coloring labels.

PubMed

Munakata, N; Ono, M; Watanabe, S

1998-03-01

To monitor personal exposure to biologically effective solar-UV radiation, Bacillus subtilis spores on a membrane filter and UV-coloring labels were incorporated into a monitoring badge. The samples were covered with one of three types of filter sheet, dependent on the season, to reduce the amounts of exposure to measurable levels. Five fifth- or sixth-grade classes of primary schools, each consisting of 30-40 children, were chosen in northern (Sapporo), central (Tsukuba and Tokyo), and southern (Miyazaki and Naha) cities in Japan. In all four season, each child wore a badge on an upper arm for the entire waking hours, changing it daily, for a week. Upon collection of the badges, the survival of spores and the extent of coloration of the label were determined. The results were used to estimate the amount of daily exposure to biologically effective UV radiation, expressed as the value of spore inactivation dose. Unexpectedly, the average amounts of exposure were not directly correlated with the outdoor UV irradiance: in the two southern cities, despite high outdoor irradiance from spring to autumn, the average amounts of exposure were less than 3.1% of the average irradiance. Highly concentrated exposures occurred in two central cities on three days when extensive outdoor exercise took place. These results contradict the simple notion that children's exposure is in proportion to the outdoor UV irradiance, and support the view that the extent of solar-UV exposure is primarily determined by life-style rather than living location.

Monitoring of Solar‐UV Exposure among Schoolchildren in Five Japanese Cities Using Spore Dosimeter and UV‐coloring Labels

PubMed Central

Ono, Masashi; Watanabe, Shaw

1998-01-01

To monitor personal exposure to biologically effective solar‐UV radiation, Bacillus subtilis spores on a membrane filter and UV‐coloring labels were incorporated into a monitoring badge. The samples were covered with one of three types of filter sheet, dependent on the season, to reduce the amounts of exposure to measurable levels. Five fifth‐ or sixth‐grade classes of primary schools, each consisting of 30–40 children, were chosen in northern (Sapporo), central (Tsukuba and Tokyo), and southern (Miyazaki and Naha) cities in Japan. In all four seasons, each child wore a badge on an upper arm for the entire waking hours, changing it daily, for a week. Upon collection of the badges, the survival of spores and the extent of coloration of the label were determined. The results were used to estimate the amount of daily exposure to biologically effective UV radiation, expressed as the value of spore inactivation dose. Unexpectedly, the average amounts of exposure were not directly correlated with the outdoor UV irradiance: in the two southern cities, despite high outdoor irradiance from spring to autumn, the average amounts of exposure were less than 3.1% of the average irradiance. Highly concentrated exposures occurred in two central cities on three days when extensive outdoor exercise took place. These results contradict the simple notion that childrens' exposure is in proportion to the outdoor UV irradiance, and support the view that the extent of solar‐UV exposure is primarily determined by life‐style rather than living location. PMID:9600116

Chemical-Induced Hearing Loss in Shipyard Workers.

PubMed

Schaal, Nicholas Cody; Slagley, Jeremy M; Richburg, Cynthia McCormick; Zreiqat, Majed M; Paschold, Helmut W

2018-01-01

The aim of this study was to determine the effect of lead, cadmium, arsenic, toluene, and xylene exposure on hearing compared with noise exposures alone. Personnel at a shipyard (n = 1266) were divided into four exposure groups on the basis of concentrations: low metals/low solvents/high noise (reference group), high metals/high solvents/low noise, high metals/low solvents/high noise, and high metals/high solvents/high noise. Hearing changes occurring from the years 2004 to 2015 were analyzed. Hearing changes were significantly worse at 1000 Hz (P = 0.007), averaged across 2000 to 4000 Hz (P = 0.014), and averaged across 500 to 6000 Hz (P = 0.014) for the high metals/high solvent/high noise group compared with the low metals/low solvents/high noise only reference group. Simultaneous exposures classified as high for metals/solvents/noise appear to damage hearing more than exposure to noise alone. Hearing conservation programs should take into consideration combined exposures to metals, solvents, and noise, not simply exposure to noise.

Radiation safety audit of a high volume Nuclear Medicine Department.

PubMed

Jha, Ashish Kumar; Singh, Abhijith Mohan; Shetye, Bhakti; Shah, Sneha; Agrawal, Archi; Purandare, Nilendu Chandrakant; Monteiro, Priya; Rangarajan, Venkatesh

2014-10-01

Professional radiation exposure cannot be avoided in nuclear medicine practices. It can only be minimized up to some extent by implementing good work practices. The aim of our study was to audit the professional radiation exposure and exposure rate of radiation worker working in and around Department of nuclear medicine and molecular imaging, Tata Memorial Hospital. We calculated the total number of nuclear medicine and positron emission tomography/computed tomography (PET/CT) procedures performed in our department and the radiation exposure to the radiation professionals from year 2009 to 2012. We performed an average of 6478 PET/CT scans and 3856 nuclear medicine scans/year from January 2009 to December 2012. The average annual whole body radiation exposure to nuclear medicine physician, technologist and nursing staff are 1.74 mSv, 2.93 mSv and 4.03 mSv respectively. Efficient management and deployment of personnel is of utmost importance to optimize radiation exposure in a high volume nuclear medicine setup in order to work without anxiety of high radiation exposure.

Residential Exposure to 50 Hz Magnetic Fields and the Association with Miscarriage Risk: A 2-Year Prospective Cohort Study

PubMed Central

Wang, Qiang; Cao, Zhaojin; Qu, Yingli; Peng, Xiaowu; Guo, Shu; Chen, Li

2013-01-01

Objective The hypothesis of whether exposure to extremely low-frequency magnetic fields (ELF-MF) may increase miscarriage risk is controversial. A 2-year prospective cohort study was designed to study the association between exposure to 50 Hz magnetic fields (MF) and the miscarriage risk for women residing in the area of the Pearl-River Delta of China. Method Two towns with densely distributed power supply constructions were selected as the study sites. From 2010 to 2012, 552 women in the region who were at approximately 8 weeks of gestation or who planned to have a baby within 1 year were selected as candidate subjects. Exposure to MF was estimated by measurements at their front doors and in the alley in front of the subjects’ houses. The average exposure level was used as a cutoff point to define the exposed group. Clinical miscarriage was diagnosed by local obstetricians. Staffs from the local population and family planning service stations were responsible for the follow-up interviews every 2 months. Results Four hundred and thirteen pregnant women were selected for the cohort study. The average residential exposure to MF was 0.099 µT. No significantly increased risk of miscarriage was found to be associated with the average front-door exposure (p>0.05). However, miscarriage risk was found to be significantly associated with maximum alley exposure (p=0.001). The relative risk (RR) of miscarriage from maximum alley exposure was 2.35 (95% C.I.: 1.18-4.71). In addition, Cox regression analysis showed that the adjusted hazard ratio of maximum alley exposure for miscarriage was 1.72 (95% C.I.:1.10-2.69). Conclusion Although the miscarriage incidence was shown to be positively associated with the maximum alley MF exposure, the association between miscarriage risk and the exposure to MF was not confirmed in the study. The results of this study are of interest concerning MF exposure assessment and pregnancy outcomes. PMID:24312633

Hand and body radiation exposure with the use of mini C-arm fluoroscopy.

PubMed

Tuohy, Christopher J; Weikert, Douglas R; Watson, Jeffry T; Lee, Donald H

2011-04-01

To determine whole body and hand radiation exposure to the hand surgeon wearing a lead apron during routine intraoperative use of the mini C-arm fluoroscope. Four surgeons (3 hand attending surgeons and 1 hand fellow) monitored their radiation exposure for a total of 200 consecutive cases (50 cases per surgeon) requiring mini C-arm fluoroscopy. Each surgeon measured radiation exposure with a badge dosimeter placed on the outside breast pocket of the lead apron (external whole body exposure), a second badge dosimeter under the lead apron (shielded whole body exposure), and a ring dosimeter (hand exposure). Completed records were noted in 198 cases, with an average fluoroscopy time of 133.52 seconds and average cumulative dose of 19,260 rem-cm(2) per case. The total measured radiation exposures for the (1) external whole body exposure dosimeters were 16 mrem (for shallow depth), 7 mrem (for eye depth), and less than 1 mrem (for deep depth); (2) shielded whole body badge dosimeters recorded less than 1 mrem; and (3) ring dosimeters totaled 170 mrem. The total radial exposure for 4 ring dosimeters that had registered a threshold of 30 mrem or more of radiation exposure was 170 mrem at the skin level, for an average of 42.5 mrem per dosimeter ring or 6.3 mrem per case. This study of whole body and hand radiation exposure from the mini C-arm includes the largest number of surgical cases in the published literature. The measured whole body and hand radiation exposure received by the hand surgeon from the mini C-arm represents a minimal risk of radiation, based on the current National Council on Radiation Protection and Management standards of annual dose limits (5,000 mrem per year for whole body and 50,000 mrem per year to the extremities). Copyright © 2011 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Impact of a smoking ban in hospitality venues on second hand smoke exposure: a comparison of exposure assessment methods

PubMed Central

2013-01-01

Background In May 2010, Switzerland introduced a heterogeneous smoking ban in the hospitality sector. While the law leaves room for exceptions in some cantons, it is comprehensive in others. This longitudinal study uses different measurement methods to examine airborne nicotine levels in hospitality venues and the level of personal exposure of non-smoking hospitality workers before and after implementation of the law. Methods Personal exposure to second hand smoke (SHS) was measured by three different methods. We compared a passive sampler called MoNIC (Monitor of NICotine) badge, to salivary cotinine and nicotine concentration as well as questionnaire data. Badges allowed the number of passively smoked cigarettes to be estimated. They were placed at the venues as well as distributed to the participants for personal measurements. To assess personal exposure at work, a time-weighted average of the workplace badge measurements was calculated. Results Prior to the ban, smoke-exposed hospitality venues yielded a mean badge value of 4.48 (95%-CI: 3.7 to 5.25; n = 214) cigarette equivalents/day. At follow-up, measurements in venues that had implemented a smoking ban significantly declined to an average of 0.31 (0.17 to 0.45; n = 37) (p = 0.001). Personal badge measurements also significantly decreased from an average of 2.18 (1.31-3.05 n = 53) to 0.25 (0.13-0.36; n = 41) (p = 0.001). Spearman rank correlations between badge exposure measures and salivary measures were small to moderate (0.3 at maximum). Conclusions Nicotine levels significantly decreased in all types of hospitality venues after implementation of the smoking ban. In-depth analyses demonstrated that a time-weighted average of the workplace badge measurements represented typical personal SHS exposure at work more reliably than personal exposure measures such as salivary cotinine and nicotine. PMID:23731820

Correlation between preconception maternal non-occupational exposure to interior decoration or oil paint odour and average birth weight of neonates: findings from a nationwide cohort study in China’s rural areas

PubMed Central

Liu, Huiting; Chen, Shi; Zhu, Huijuan; Yang, Hongbo; Gong, Fengying; Wang, Linjie; Jiang, Yu; Lian, Bill Q; Yan, Chengsheng; Li, Jianqang; Wang, Qing; Zhang, Shikun; Pan, Hui

2017-01-01

Background Birth weight is a critical indicator of neonatal health and foretells people’s health in adolescence and even adulthood. Some researchers have warned against the adverse effects on babies’ birth weight of exposure to pollutants in interior decoration or oil paint by odour intake. This study evaluated the effects of maternal exposure to such factors before conception on the birth weights of neonates. Methods Data on 213 461 cases in this study were from the database of the free National Pre-pregnancy Checkups Project. Defined as ‘exposed’ were those women exposed to oil paint odour or interior decoration at home or in the workplace within 6 months before their pregnancy. The study focused on revealing the correlation between such exposure and the birth weight of the neonates of these women, especially the incidence of macrosomia and low birth weight (LBW). Statistical analysis was conducted using the Kruskal–Wallis H test, the Mann–Whitney U test and logistic regression. Results The birth weight of babies from mothers non-occupationally exposed to such settings averaged 3465 g (range 3150–3650 g), whereas the birth weight of those from mothers free of such exposure averaged 3300 g (range 3000–3600g). Maternal exposure preconception to interior decoration or oil paint odour reduced the incidence of LBW in their babies (p=0.003, OR 0.749, 95% CI 0.617 to 0.909). Such exposure may also augment the probability of macrosomia (p<0.001, OR 1.297, 95% CI 1.133 to 1.484). Conclusion Maternal exposure to interior decoration or oil paint odour preconception may increase the average birth weight of neonates, as well as the incidence of macrosomia. PMID:28827230

Impact of a smoking ban in hospitality venues on second hand smoke exposure: a comparison of exposure assessment methods.

PubMed

Rajkumar, Sarah; Huynh, Cong Khanh; Bauer, Georg F; Hoffmann, Susanne; Röösli, Martin

2013-06-04

In May 2010, Switzerland introduced a heterogeneous smoking ban in the hospitality sector. While the law leaves room for exceptions in some cantons, it is comprehensive in others. This longitudinal study uses different measurement methods to examine airborne nicotine levels in hospitality venues and the level of personal exposure of non-smoking hospitality workers before and after implementation of the law. Personal exposure to second hand smoke (SHS) was measured by three different methods. We compared a passive sampler called MoNIC (Monitor of NICotine) badge, to salivary cotinine and nicotine concentration as well as questionnaire data. Badges allowed the number of passively smoked cigarettes to be estimated. They were placed at the venues as well as distributed to the participants for personal measurements. To assess personal exposure at work, a time-weighted average of the workplace badge measurements was calculated. Prior to the ban, smoke-exposed hospitality venues yielded a mean badge value of 4.48 (95%-CI: 3.7 to 5.25; n = 214) cigarette equivalents/day. At follow-up, measurements in venues that had implemented a smoking ban significantly declined to an average of 0.31 (0.17 to 0.45; n = 37) (p = 0.001). Personal badge measurements also significantly decreased from an average of 2.18 (1.31-3.05 n = 53) to 0.25 (0.13-0.36; n = 41) (p = 0.001). Spearman rank correlations between badge exposure measures and salivary measures were small to moderate (0.3 at maximum). Nicotine levels significantly decreased in all types of hospitality venues after implementation of the smoking ban. In-depth analyses demonstrated that a time-weighted average of the workplace badge measurements represented typical personal SHS exposure at work more reliably than personal exposure measures such as salivary cotinine and nicotine.

Time-varying cycle average and daily variation in ambient air pollution and fecundability.

PubMed

Nobles, Carrie J; Schisterman, Enrique F; Ha, Sandie; Buck Louis, Germaine M; Sherman, Seth; Mendola, Pauline

2018-01-01

Does ambient air pollution affect fecundability? While cycle-average air pollution exposure was not associated with fecundability, we observed some associations for acute exposure around ovulation and implantation with fecundability. Ambient air pollution exposure has been associated with adverse pregnancy outcomes and decrements in semen quality. The LIFE study (2005-2009), a prospective time-to-pregnancy study, enrolled 501 couples who were followed for up to one year of attempting pregnancy. Average air pollutant exposure was assessed for the menstrual cycle before and during the proliferative phase of each observed cycle (n = 500 couples; n = 2360 cycles) and daily acute exposure was assessed for sensitive windows of each observed cycle (n = 440 couples; n = 1897 cycles). Discrete-time survival analysis modeled the association between fecundability and an interquartile range increase in each pollutant, adjusting for co-pollutants, site, age, race/ethnicity, parity, body mass index, smoking, income and education. Cycle-average air pollutant exposure was not associated with fecundability. In acute models, fecundability was diminished with exposure to ozone the day before ovulation and nitrogen oxides 8 days post ovulation (fecundability odds ratio [FOR] 0.83, 95% confidence interval [CI]: 0.72, 0.96 and FOR 0.84, 95% CI: 0.71, 0.99, respectively). However, particulate matter ≤10 microns 6 days post ovulation was associated with greater fecundability (FOR 1.25, 95% CI: 1.01, 1.54). Although our study was unlikely to be biased due to confounding, misclassification of air pollution exposure and the moderate study size may have limited our ability to detect an association between ambient air pollution and fecundability. While no associations were observed for cycle-average ambient air pollution exposure, consistent with past research in the United States, exposure during critical windows of hormonal variability was associated with prospectively measured couple fecundability, warranting further investigation. This work was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (Longitudinal Investigation of Fertility and the Environment study contract nos. #N01-HD-3-3355, NO1-HD-#-3356, N01-HD-3-3358 and the Air Quality and Reproductive Health Study Contract No. HHSN275200800002I, Task Order No. HHSN27500008). We declare no conflict of interest. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Reduction of Averaging Time for Evaluation of Human Exposure to Radiofrequency Electromagnetic Fields from Cellular Base Stations

NASA Astrophysics Data System (ADS)

Kim, Byung Chan; Park, Seong-Ook

In order to determine exposure compliance with the electromagnetic fields from a base station's antenna in the far-field region, we should calculate the spatially averaged field value in a defined space. This value is calculated based on the measured value obtained at several points within the restricted space. According to the ICNIRP guidelines, at each point in the space, the reference levels are averaged over any 6min (from 100kHz to 10GHz) for the general public. Therefore, the more points we use, the longer the measurement time becomes. For practical application, it is very advantageous to spend less time for measurement. In this paper, we analyzed the difference of average values between 6min and lesser periods and compared it with the standard uncertainty for measurement drift. Based on the standard deviation from the 6min averaging value, the proposed minimum averaging time is 1min.

Reduction in radiation exposure to nursing personnel with the use of remote afterloading brachytherapy devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigsby, P.W.; Perez, C.A.; Eichling, J.

The radiation exposure to nursing personnel from patients with brachytherapy implants on a large brachytherapy service were reviewed. Exposure to nurses, as determined by TLD monitors, indicates a 7-fold reduction in exposure after the implementation of the use of remote afterloading devices. Quarterly TLD monitor data for six quarters prior to the use of remote afterloading devices demonstrate an average projected annual dose equivalent to the nurses of 152 and 154 mrem (1.5 mSv). After the implementation of the remote afterloading devices, the quarterly TLD monitor data indicate an average dose equivalent per nurse of 23 and 19 mrem (0.2more » mSv). This is an 87% reduction in exposure to nurses with the use of these devices (p less than 0.01).« less

Results of step-cut medial malleolar osteotomy.

PubMed

Thordarson, David B; Kaku, Shawn K

2006-12-01

Treatment of certain complex ankle pathology, such as a talar body fracture or osteochondral lesion requiring grafting, can necessitate medial malleolar osteotomy for adequate operative exposure. This paper evaluates the step-cut medial malleolar osteotomy for exposure of the ankle joint. Fourteen patients with intra-articular pathology, including talar body fractures or osteochondral lesions necessitating extensive intra-articular exposure had step-cut malleolar osteotomy. The average age of the patients was 37 (range 20-90) years, and the average followup was 8 months. All 14 patients had an uncomplicated intraoperative course, with excellent exposure of the ankle joint. All patients had prompt healing of the osteotomy by 6 weeks after surgery without loss of reduction. None of the patients had pain at the osteotomy site. Step-cut medial malleolar osteotomy is an excellent, reproducible method for extensive exposure of the talar dome.

Acute Effects of Fine Particulate Air Pollution on Cardiac Arrhythmia: The APACR Study

PubMed Central

He, Fan; Shaffer, Michele L.; Rodriguez-Colon, Sol; Yanosky, Jeff D.; Bixler, Edward; Cascio, Wayne E.

2011-01-01

Background: The mechanisms underlying the relationship between particulate matter (PM) air pollution and cardiac disease are not fully understood. Objectives: We examined the effects and time course of exposure to fine PM [aerodynamic diameter ≤ 2.5 μm (PM2.5)] on cardiac arrhythmia in 105 middle-age community-dwelling healthy nonsmokers in central Pennsylvania. Methods: The 24-hr beat-to-beat electrocardiography data were obtained using a high-resolution Holter system. After visually identifying and removing artifacts, we summarized the total number of premature ventricular contractions (PVCs) and premature atrial contractions (PACs) for each 30-min segment. A personal PM2.5 nephelometer was used to measure individual-level real-time PM2.5 exposures for 24 hr. We averaged these data to obtain 30-min average time–specific PM2.5 exposures. Distributed lag models under the framework of negative binomial regression and generalized estimating equations were used to estimate the rate ratio between 10-μg/m3 increases in average PM2.5 over 30-min intervals and ectopy counts. Results: The mean ± SD age of participants was 56 ± 8 years, with 40% male and 73% non-Hispanic white. The 30-min mean ± SD for PM2.5 exposure was 13 ± 22 μg/m3, and PAC and PVC counts were 0.92 ± 4.94 and 1.22 ± 7.18. Increases of 10 μg/m3 in average PM2.5 concentrations during the same 30 min or the previous 30 min were associated with 8% and 3% increases in average PVC counts, respectively. PM2.5 was not significantly associated with PAC count. Conclusion: PM2.5 exposure within approximately 60 min was associated with increased PVC counts in healthy individuals. PMID:21398201

USE OF A CONTINUOUS NEPHELOMETER TO MEASURE PERSONAL EXPOSURE TO PARTICLES DURING THE U.S. EPA BALTIMORE AND FRESNO PANEL STUDIES

EPA Science Inventory

In population exposure studies, personal exposure to particulate matter (PM) is typically measured as a 12- to 24-hour integrated mass concentration. To better understand short-term variation in personal PM exposure, continuous (one-minute averaging time) nephelometers were wo...

Effects of intense tone exposure on choline acetyltransferase activity in the hamster cochlear nucleus.

PubMed

Jin, Yong-Ming; Godfrey, Donald A; Wang, Jie; Kaltenbach, James A

2006-01-01

Choline acetyltransferase (ChAT) activity has been mapped in the cochlear nucleus (CN) of control hamsters and hamsters that had been exposed to an intense tone. ChAT activity in most CN regions of hamsters was only a third or less of the activity in rat CN, but in granular regions ChAT activity was similar in both species. Eight days after intense tone exposure, average ChAT activity increased on the tone-exposed side as compared to the opposite side, by 74% in the anteroventral CN (AVCN), by 55% in the granular region dorsolateral to it, and by 74% in the deep layer of the dorsal CN (DCN). In addition, average ChAT activity in the exposed-side AVCN and fusiform soma layer of DCN was higher than in controls, by 152% and 67%, respectively. Two months after exposure, average ChAT activity was still 53% higher in the exposed-side deep layer of DCN as compared to the opposite side. Increased ChAT activity after intense tone exposure may indicate that this exposure leads to plasticity of descending cholinergic innervation to the CN, which might affect spontaneous activity in the DCN that has been associated with tinnitus.

Women's Reasons for Leaving the Engineering Field.

PubMed

Fouad, Nadya A; Chang, Wen-Hsin; Wan, Min; Singh, Romila

2017-01-01

Among the different Science, Technology, Engineering, and Math fields, engineering continues to have one of the highest rates of attrition (Hewlett et al., 2008). The turnover rate for women engineers from engineering fields is even higher than for men (Frehill, 2010). Despite increased efforts from researchers, there are still large gaps in our understanding of the reasons that women leave engineering. This study aims to address this gap by examining the reasons why women leave engineering. Specifically, we analyze the reasons for departure given by national sample of 1,464 women engineers who left the profession after having worked in the engineering field. We applied a person-environment fit theoretical lens, in particular, the Theory of Work Adjustment (TWA) (Dawis and Lofquist, 1984) to understand and categorize the reasons for leaving the engineering field. According to the TWA, occupations have different "reinforcer patterns," reflected in six occupational values, and a mismatch between the reinforcers provided by the work environment and individuals' needs may trigger departure from the environment. Given the paucity of literature in this area, we posed research questions to explore the reinforcer pattern of values implicated in women's decisions to leave the engineering field. We used qualitative analyses to understand, categorize, and code the 1,863 statements that offered a glimpse into the myriad reasons that women offered in describing their decisions to leave the engineering profession. Our results revealed the top three sets of reasons underlying women's decision to leave the jobs and engineering field were related to: first, poor and/or inequitable compensation, poor working conditions, inflexible and demanding work environment that made work-family balance difficult; second, unmet achievement needs that reflected a dissatisfaction with effective utilization of their math and science skills, and third, unmet needs with regard to lack of recognition at work and adequate opportunities for advancement. Implications of these results for future research as well as the design of effective intervention programs aimed at women engineers' retention and engagement in engineering are discussed.

Nicotine and Carbon Monoxide Exposure from Inhalation of Cigarillo Smoke

PubMed Central

Koszowski, Bartosz; Rosenberry, Zachary R.; Kanu, Alieu; Viray, Lauren C.; Potts, Jennifer L.; Pickworth, Wallace B.

2015-01-01

Background There has been an increase in the use of cigarillos in the US. People who smoke cigarillos typically also regularly smoke cigarettes (dual users). Methods We compared puffing topography, biomarkers of acute exposure [exhaled carbon monoxide (COex) and plasma nicotine] and physiologic effects from usual brand cigarette and Black & Mild cigarillo smoking in dual users (N=23) in two laboratory sessions. Results Participants (21 men) smoked an average of 17.5 cigarettes/day. Cigarillo consumption varied widely from as few as 1/week to daily. Participants were highly nicotine dependent (average FTND score: 6.3). There were statistically significant differences in smoking behavior between cigarette and cigarillo smoking in time to smoke, number of puffs, and total puff volume (all P<0.001). Average puff duration, interpuff interval average puff volume, and puff velocity did not differ between cigarettes and cigarillos. Nicotine boost was similar after both cigarettes and cigarillos. COex boost was significantly greater after cigarillo smoking compared to cigarette smoking (P<0.001). Conclusions The smoking pattern and exposure profile indicate that dual users inhale cigarillo smoke just as they inhale cigarette smoke thereby exposing themselves to considerable amounts of nicotine and other components of tobacco smoke. COex exposure results imply that cigarillo smoking may be associated with higher exposure to smoke-delivered volatile components of mainstream cigarillo smoke including carcinogens when compared to cigarettes. Impact The findings that cigarillos and cigarettes are smoked similarly in dual users are relevant to health and regulatory considerations on cigar products. PMID:26459155

VARIATIONS IN PEAK EXPIRATORY FLOW MEASUREMENTS ASSOCIATED TO AIR POLLUTION AND ALLERGIC SENSITIZATION IN CHILDREN IN SAO PAULO, BRAZIL

PubMed Central

de M Correia-Deur, Joya Emilie; Claudio, Luz; Imazawa, Alice Takimoto; Eluf-Neto, Jose

2012-01-01

Background In the last 20 years, there has been an increase in the incidence of allergic respiratory diseases worldwide and exposure to air pollution has been discussed as one of the factors associated with this increase. The objective of this study was to investigate the effects of air pollution on peak expiratory flow (PEF) and FEV1 in children with and without allergic sensitization. Methods Ninety-six children were followed from April to July, 2004 with spirometry measurements. They were tested for allergic sensitization (IgE, skin prick test, eosinophilia) and asked about allergic symptoms. Air pollution, temperature and relative humidity data were available. Results Decrements in PEF were observed with previous 24-h average exposure to air pollution, as well as with 3 to 10 day average exposure and were associated mainly with PM10, NO2 and O3. in all three categories of allergic sensitization. Even though allergic sensitized children tended to present larger decrements in the PEF measurements they were not statistically different from the non-allergic sensitized. Decrements in FEV1 were observed mainly with previous 24-h average exposure and 3-day moving average. Conclusions Decrements in PEF associated with air pollution were observed in children independent from their allergic sensitization status. Their daily exposure to air pollution can be responsible for a chronic inflammatory process that might impair their lung growth and later their lung function in adulthood. PMID:22544523

Ischemic heart disease and ambient air pollution of particulate matter 2.5 in 51 counties in the U.S.

PubMed

Balluz, Lina; Wen, Xiao-Jun; Town, Machell; Shire, Jeffrey D; Qualter, Judy; Mokdad, Ali

2007-01-01

Ischemic heart disease (IHD) is one of the most common health threats to the adult population of the U.S. and other countries. The objective of this study was to examine the association between exposure to elevated annual average levels of Particulate matter 2.5 (PM2.5) air quality index (AQI) and IHD in the general population. We combined data from the Behavioral Risk Factor Surveillance System and the U.S Environmental Protection Agency air quality database. We analyzed the data using SUDAAN software to adjust the effects of sampling bias, weights, and design effects. The prevalence of IHD was 9.6% among respondents who were exposed to an annual average level of PM2.5 AQI > 60 compared with 5.9% among respondents exposed to an annual average PM2.5 AQI < or = 60. The respondents with higher levels of PM2.5 AQI exposure were more likely to have IHD (adjusted odds ratio = 1.72, 95% confidence interval 1.11, 2.66) than respondents with lower levels of exposure after adjusting for age, gender, race/ethnicity, education, smoking, body mass index, diabetes, hypertension, and hypercholesterolemia. Our study suggested that exposure to relatively higher levels of average annual PM2.5 AQI may increase the likelihood of IHD. In addition to encouraging health-related behavioral changes to reduce IHD, efforts should also focus on implementing appropriate measures to reduce exposure to unhealthy AQI levels.

Managing Exposure to Benzene and Total Petroleum Hydrocarbons at Two Oil Refineries 1977-2014.

PubMed

Tuomi, Tapani; Veijalainen, Henna; Santonen, Tiina

2018-01-24

Air concentrations of and inhalation exposure to total petroleum hydrocarbons (TPH) and benzene was monitored separately at two oil refineries from 1977 to 2014. Prevention policies and control measures that may explain changes were surveyed. The aim was to evaluate how the application of of Occupational Health and Safety Assessment Series OHSAS 18001.04 principles as well as Environmental protection Agency EPA and European Oil Company Organisation for Environment, Health and Safety CONCAWE practices have influenced air concentrations. Benzene air concentrations declined in 11 of 17 units, six of which were associated with declining exposures. Benzene air concentrations declined across all units on average by 46%. This amounts to an average yearly decline of 1.7%. TPH air concentrations declined in 10 of 17 units, seven of which were associated with declining exposures. The average decline in TPH air concentrations was 49%, corresponding to 1.3% per year. As a result, average working day exposure in 10 of 17 units have declined significantly and today, benzene and TPH exposure in most units are well below 10% of the current Occupational Exposure Limit (OEL 8h :s). A decline in air concentrations have coincided with consistent implementation of control measures. Such measures include on-line monitoring of leaks; benzene recovery; floating container roofs; improved valves and seals; hermetic pumps; recovery of loading gases and instalment of torches in terminals; cutback in coke combustion; a new production line spanning directly from the dock to aromatics production; and recovery of loading gases in the doc. Other tools in exposure management include personal leak monitors, on-line measurements, monitoring campaigns, risk assessment, and availability and user training of protective equipment. However, improvements are still needed. Hydrocarbon or benzene air concentrations have not declined in 8 of 17 units, in some of which concentrations exceed 10% of the relevant OEL 8h value. In addition, for benzene even 10% of the current OEL, 0.1 ppm, might still possess a risk. With this in mind, methods to estimate exposure at the refineries need to be improved to enable measuring benzene concentrations <0.1 ppm. Shut downs of the refinery have been associated with peaks in exposure concentrations. Consequently, effort should be placed on safe working methods pertaining to shutdowns. Also, the connection and detachment of hoses continues to be problematic from the point of view of controlling exposure.

Managing risks of noncancer health effects at hazardous waste sites: A case study using the Reference Concentration (RfC) of trichloroethylene (TCE).

PubMed

Dourson, Michael L; Gadagbui, Bernard K; Thompson, Rod B; Pfau, Edward J; Lowe, John

2016-10-01

A method for determining a safety range for non-cancer risks is proposed, similar in concept to the range used for cancer in the management of waste sites. This safety range brings transparency to the chemical specific Reference Dose or Concentration by replacing their "order of magnitude" definitions with a scientifically-based range. EPA's multiple RfCs for trichloroethylene (TCE) were evaluated as a case study. For TCE, a multi-endpoint safety range was judged to be 3 μg/m(3) to 30 μg/m,(3) based on a review of kidney effects found in NTP (1988), thymus effects found in Keil et al. (2009) and cardiac effects found in the Johnson et al. (2003) study. This multi-endpoint safety range is derived from studies for which the appropriate averaging time corresponds to different exposure durations, and, therefore, can be applied to both long- and short-term exposures with appropriate consideration of exposure averaging times. For shorter-term exposures, averaging time should be based on the time of cardiac development in humans during fetal growth, an average of approximately 20-25 days. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Assessing multimedia/multipathway exposures to inorganic arsenic at population and individual level using MERLIN-Expo.

PubMed

Van Holderbeke, Mirja; Fierens, Tine; Standaert, Arnout; Cornelis, Christa; Brochot, Céline; Ciffroy, Philippe; Johansson, Erik; Bierkens, Johan

2016-10-15

In this study, we report on model simulations performed using the newly developed exposure tool, MERLIN-Expo, in order to assess inorganic arsenic (iAs) exposure to adults resulting from past emissions by non-ferrous smelters in Belgium (Northern Campine area). Exposure scenarios were constructed to estimate external iAs exposure as well as the toxicologically relevant As (tAs, i.e., iAs, MMA and DMA) body burden in adults living in the vicinity of the former industrial sites as compared to adults living in adjacent areas and a reference area. Two scenarios are discussed: a first scenario studying exposure to iAs at the aggregated population level and a second scenario studying exposure at the individual level for a random sub-sample of subjects in each of the three different study areas. These two scenarios only differ in the type of human related input data (i.e., time-activity data, ingestion rates and consumption patterns) that were used, namely averages (incl. probability density functions, PDFs) in the simulation at population level and subject-specific values in the simulation at individual level. The model predictions are shown to be lower than the corresponding biomonitoring data from the monitoring campaign. Urinary tAs levels in adults, irrespective of the area they lived in, were under-predicted by MERLIN-Expo by 40% on average. The model predictions for individual adults, by contrast, under-predict the biomonitoring data by 7% on average, but with more important under-predictions for subjects at the upper end of exposure. Still, average predicted urinary tAs levels from the simulations at population level and at individual level overlap, and, at least for the current case, lead to similar conclusions. These results constitute a first and partial verification of the model performance of MERLIN-Expo when dealing with iAs in a complex site-specific exposure scenario, and demonstrate the robustness of the modelling tool for these situations. Copyright © 2016 Elsevier B.V. All rights reserved.

[Occupational exposure to wood dust and nasal sinus cancer].

PubMed

Fontana, L; Liétin, B; Catilina, P; Devif, C; Féneon, B; Martin, F; Mom, T; Gilain, L

2008-04-01

To determine the clinical, histological, epidemiological and occupational data related to exposure to wood dust in a series of 100 nasal sinus malignant tumors. We conducted a retrospective and descriptive study of cases diagnosed between 1st January 1981 and 31 December 2000, in the Auvergne region of France. Individual, medical, and occupational data were collected from a questionnaire completed by the patient (or the patient's family in case of death) and from the medical documents available. Forty-six cases (46 men), with an average age of 63+/-9.2 years [range, 43-82], had been exposed to occupational wood dust before the diagnosis. Fifty-four cases (30 men, 24 women), with an average age of 64.3+/-8.7 years [range, 40-96], had never been exposed. The average annual incidence increased, either for the total population or for the two subgroups distinguished on the basis of occupational exposure to wood dust. The majority of the patients presented different functional symptoms at the time of the diagnosis. For the 46 patients exposed to wood dust, the tumors were primarily ethmoid adenocarcinomas (92%). For the 54 non-exposed patients, the tumors observed were mainly epidermoid carcinomas (57%), then adenocarcinomas (15%). On the 46 patients exposed to wood dust, 85% were carpenters or cabinetmakers. For the majority of the patients, wood dust exposure started before the age of 20 (average age: 17+/-4.5) and the longest exposure began before 1981. The exposure time to wood dust before diagnosis was in the majority of cases greater than 20 years (mean exposure time: 37 years+/-11.4). Only 15% were exposed at the time of the diagnosis (mean time between the end of the exposure to the diagnosis was 11 years+/-2.8). Of the 54 non-exposed patients, no professional risk factor was evidenced. Epidemiologic data, such as the increasing incidence, and clinical and professional data, such as the occupational exposure to wood dust, were in agreement with the French and European literature. It is still probably too early to appreciate the effectiveness of prevention, established in France since 1980, on nasal sinus tumor incidence.

Understanding the exposure-time effect on speckle contrast measurements for laser displays

NASA Astrophysics Data System (ADS)

Suzuki, Koji; Kubota, Shigeo

2018-02-01

To evaluate the influence of exposure time on speckle noise for laser displays, speckle contrast measurement method was developed observable at a human eye response time using a high-sensitivity camera which has a signal multiplying function. The nonlinearity of camera light sensitivity was calibrated to measure accurate speckle contrasts, and the measuring lower limit noise of speckle contrast was improved by applying spatial-frequency low pass filter to the captured images. Three commercially available laser displays were measured over a wide range of exposure times from tens of milliseconds to several seconds without adjusting the brightness of laser displays. The speckle contrast of raster-scanned mobile projector without any speckle-reduction device was nearly constant over various exposure times. On the contrary to this, in full-frame projection type laser displays equipped with a temporally-averaging speckle-reduction device, some of their speckle contrasts close to the lower limits noise were slightly increased at the shorter exposure time due to the noise. As a result, the exposure-time effect of speckle contrast could not be observed in our measurements, although it is more reasonable to think that the speckle contrasts of laser displays, which are equipped with the temporally-averaging speckle-reduction device, are dependent on the exposure time. This discrepancy may be attributed to the underestimation of temporal averaging factor. We expected that this method is useful for evaluating various laser displays and clarify the relationship between the speckle noise and the exposure time for a further verification of speckle reduction.

Impact of time-activity patterns on personal exposure to black carbon

NASA Astrophysics Data System (ADS)

Dons, Evi; Int Panis, Luc; Van Poppel, Martine; Theunis, Jan; Willems, Hanny; Torfs, Rudi; Wets, Geert

2011-07-01

Time-activity patterns are an important determinant of personal exposure to air pollution. This is demonstrated by measuring personal exposure of 16 participants for 7 consecutive days: 8 couples of which one person was a full-time worker and the other was a homemaker; both had a very different time-activity pattern. We used portable aethalometers to measure black carbon levels with a high temporal resolution and a PDA with GPS-logger and electronic diary. The exposure to black carbon differs between partners by up to 30%, although they live at the same location. The activity contributing most to this difference is transport: Average exposure in transport is 6445 ng m -3, followed by exposure during shopping (2584 ng m -3). Average exposure is lowest while sleeping (1153 ng m -3) and when doing home-based activities (1223 ng m -3). Full-time workers spend almost twice as much time in transport as the homemakers. As a result of the study design we measured in several different homes, shops, cars, etc. enabling a better insight in true overall exposure in those microenvironments. Other factors influencing personal exposure are: background concentrations and location of residence in an urban, suburban or rural environment.

Human exposures to pesticides in the United States.

PubMed

Langley, Ricky L; Mort, Sandra Amiss

2012-01-01

Pesticides are used in most homes, businesses, and farms to control a variety of pests, including insects, weeds, fungi, rodents, and even microbial organisms. Inappropriate use of pesticides can lead to adverse effects to humans and the environment. This study provides updated information on the magnitude of adverse pesticide exposures in the United States. Data on pesticide exposure were obtained from calls to poison control centers (PCCs) reported by the American Association of Poison Control Centers. Estimates of emergency department visits, hospitalizations, and health care costs were reported by the Agency for Healthcare Research and Quality (AHRQ), and deaths from pesticide poisonings reported by the Centers for Disease Control and Prevention (CDC) WONDER (Wide-ranging Online Data for Epidemiologic Research). An average of 23 deaths occur each year with pesticides as the underlying cause of death, most due to suicidal ingestions. An average of 130,136 calls to poison control centers were reported from 2006 to 2010, with an average of 20,116 cases (17.8%) treated in health care facilities annually. AHQR reported an annual average of 7385 emergency room visits during 2006 to 2008, and 1419 annual hospitalizations during 2005 to 2009. Excluding cost from lost work time, hospital physician fees, and pesticide-induced cancers, the annual national cost associated with pesticide exposures was estimated as nearly $200 million USD based on data from emergency department visits, hospitalizations, and for deaths. Pesticide exposures remain a significant public health issue. Health care providers, cooperative extension agents, and pesticide manufactures can help prevent exposures by increasing education of parents and workers, encourage use of less toxic agents, and encourage the practice of integrated pest management.

Measurement of volatile organic compounds inside automobiles.

PubMed

Fedoruk, Marion J; Kerger, Brent D

2003-01-01

The objective of the current study was to evaluate the types and concentrations of volatile organic compounds (VOCs) in the passenger cabin of selected sedan automobiles under static (parked, unventilated) and specified conditions of operation (i.e., driving the vehicle using air conditioning alone, vent mode alone, or driver's window half open). Data were collected on five different passenger sedan vehicles from three major automobile manufacturers. Airborne concentrations were assessed using 90-min time-weighted average (TWA) samples under U.S. Environmental Protection Agency (USEPA) Method IP-1B to assess individual VOC compounds and total VOCs (TVOCs) calibrated to toluene. Static vehicle testing demonstrated TVOC levels of approximately 400-800 microg/m(3) at warm interior vehicle temperatures (approximately 80 degrees F), whereas TVOCs at least fivefold higher were observed under extreme heat conditions (e.g., up to 145 degrees F). The profile of most prevalent individual VOC compounds varied considerably according to vehicle brand, age, and interior temperature tested, with predominant compounds including styrene, toluene, and 8- to 12-carbon VOCs. TVOC levels under varied operating conditions (and ventilation) were generally four- to eightfold lower (at approximately 50-160 microg/m(3)) than the static vehicle measurements under warm conditions, with the lowest measured levels generally observed in the trials with the driver's window half open. These data indicate that while relatively high concentrations of certain VOCs can be measured inside static vehicles under extreme heat conditions, normal modes of operation rapidly reduce the inside-vehicle VOC concentrations even when the air conditioning is set on recirculation mode.

Swimmer illness associated with marine water exposure and water quality indicators: impact of widely used assumptions

EPA Science Inventory

Studies of health risks associated with recreational water exposure require investigators to make choices about water quality indicator averaging techniques, exposure definitions, follow-up periods, and model specifications; but, investigators seldom describe the impact of these ...

Biomonitoring of polycyclic aromatic hydrocarbon exposure in pregnant women in Trujillo, Peru — Comparison of different fuel types used for cooking☆

PubMed Central

Adetona, Olorunfemi; Li, Zheng; Sjödin, Andreas; Romanoff, Lovisa C.; Aguilar-Villalobos, Manuel; Needham, Larry L.; Hall, Daniel B.; Cassidy, Brandon E.; Naeher, Luke P.

2016-01-01

Women and children in developing countries are often exposed to high levels of air pollution including polycyclic aromatic hydrocarbons (PAHs), which may negatively impact their health, due to household combustion of biomass fuel for cooking and heating. We compared creatinine adjusted hydroxy-PAH (OH-PAH) concentrations in pregnant women in Trujillo, Peru who cook with wood to levels measured in those who cook with kerosene, liquefied petroleum gas or a combination of fuels. Seventy-nine women were recruited for the study between May and July 2004 in the first trimester of their pregnancy. Urine samples were collected from the subjects in the first, second and third trimesters for OH-PAH analyses. The concentrations of the OH-PAHs were compared across the type of fuel used for cooking and pregnancy trimesters. The relationships between OH-PAHs levels in the first trimester and concurrently measured personal exposures to PM2.5, carbon monoxide and nitrogen dioxide together with their indoor and outdoor air concentrations were also investigated. Women cooking with wood or kerosene had the highest creatinine adjusted OH-PAH concentrations compared with those using gas, coal briquette or a combination of fuels. Concentrations of creatinine adjusted 2-hydroxy-fluorene, 3-hydroxy-fluorene, 1-hydroxy-fluorene, 2-hydroxy-phenanthrene and 4-hydroxy-phenanthrene were significantly higher (p<0.05) in women who used wood or kerosene alone compared with women who used liquefied petroleum gas (LPG), coal briquette or a combination of fuels. An increase in the concentrations of creatinine adjusted 9-hydroxy-fluorene, 1-hydroxy-phenanthrene, 2-hydroxy-phenanthrene, 4-hydroxy-phenanthrene and 1-hydroxy-pyrene in the third trimesters was also observed. Weak positive correlation (Spearman correlation coefficient, ρ<0.4; p<0.05) was observed between all first trimester creatinine adjusted OH-PAHs and indoor (kitchen and living room), and personal 48-h TWA PM2.5. Women who cooked exclusively with wood or kerosene had higher creatinine adjusted OH-PAH levels in their urine samples compared to women who cooked with LPG or coal briquette. PMID:23314038

Evaluation of radiation exposure with Tru-Align intraoral rectangular collimation system using OSL dosimeters.

PubMed

Goren, Arthur D; Bonvento, Michael J; Fernandez, Thomas J; Abramovitch, Kenneth; Zhang, Wenjian; Roe, Nadine; Seltzer, Jared; Steinberg, Mitchell; Colosi, Dan C

2011-03-01

A pilot study to compare radiation exposure with the Tru-Align rectangular collimation system to round collimation exposures was undertaken. Radiation exposure at various points within the cross sections of the collimators and entrance, intraoral and exit dose measurements were measured using InLight OSL dosimeters. Overall dose reduction with the use of the rectangular collimation system was estimated by taking into account the ratios of collimator openings and the average radiation exposure at the measurement points. Use of the Tru-Align system resulted in an average radiation exposure within the perimeter of the projected outline of the rectangular collimator of 36.1 mR, compared to 148.5 mR with the round collimator. Our calculations indicate a dose reduction by a factor of approximately 3.2 in the case of the Tru-Align system compared to round collimation. The Tru-Align system was easy to use, but in some situations failed to allow Xray coverage of the entire surface of the image receptor, leading to cone cuts.

PERSONAL MEASURES OF POWER-FREQUENCY MAGNETIC FIELD EXPOSURE AMONG MEN FROM AN INFERTILITY CLINIC: DISTRIBUTION, TEMPORAL VARIABILITY AND CORRELATION WITH THEIR FEMALE PARTNERS' EXPOSURE

PubMed Central

Lewis, Ryan C.; Hauser, Russ; Maynard, Andrew D.; Neitzel, Richard L.; Wang, Lu; Kavet, Robert; Morey, Patricia; Ford, Jennifer B.; Meeker, John D.

2016-01-01

Power-frequency magnetic field exposure science as it relates to men and couples have not been explored despite the advantage of this information in the design and interpretation of reproductive health epidemiology studies. This analysis examined the distribution and temporal variability of exposures in men, and the correlation of exposures within couples using data from a longitudinal study of 25 men and their female partners recruited from an infertility clinic. The average and 90th percentile demonstrated fair to good reproducibility, whereas the maximum showed poor reproducibility over repeated sampling days, each separated by a median of 4.6 weeks. Average magnetic field exposures were also strongly correlated within couples, suggesting that one partner's data could be used as a surrogate in the absence of data from the other for this metric. Environment was also an important effect modifier in these explored matters. These issues should be considered in future relevant epidemiology studies. PMID:26705359

Estimates of Ethanol Exposure in Children from Food not Labeled as Alcohol-Containing

PubMed Central

Gorgus, Eva; Hittinger, Maike; Schrenk, Dieter

2016-01-01

Abstract Ethanol is widely used in herbal medicines, e.g., for children. Furthermore, alcohol is a constituent of fermented food such as bread or yogurt and “non-fermented” food such as fruit juices. At the same time, exposure to very low levels of ethanol in children is discussed as possibly having adverse effects on psychomotoric functions. Here, we have analyzed alcohol levels in different food products from the German market. It was found that orange, apple and grape juice contain substantial amounts of ethanol (up to 0.77 g/L). Furthermore, certain packed bakery products such as burger rolls or sweet milk rolls contained more than 1.2 g ethanol/100 g. We designed a scenario for average ethanol exposure by a 6-year-old child. Consumption data for the “categories” bananas, bread and bakery products and apple juice were derived from US and German surveys. An average daily exposure of 10.3 mg ethanol/kg body weight (b.w.) was estimated. If a high (acute) consumption level was assumed for one of the “categories,” exposure rose to 12.5–23.3 mg/kg b.w. This amount is almost 2-fold (average) or up to 4-fold (high) higher than the lowest exposure from herbal medicines (6 mg/kg b.w.) suggested to require warning hints for the use in children. PMID:27405361

Use of prostate-specific antigen (PSA) to measure semen exposure resulting from male condom failures: implications for contraceptive efficacy and the prevention of sexually transmitted disease.

PubMed

Walsh, Terri L; Frezieres, Ron G; Peacock, Karen; Nelson, Anita L; Clark, Virginia A; Bernstein, Leslie; Wraxall, Brian G D

2003-02-01

Accurate measurement of semen exposure resulting from condom failures can refine public health messages and improve predictions of condom efficacy in preventing pregnancy and HIV transmission. Eight hundred and thirty couples enrolled in a condom efficacy study were asked to collect a baseline sample of ejaculate from the inside of the first study condom they used and to collect a postcoital vaginal sample whenever a study condom broke or slipped off during intercourse. All samples were quantitatively tested for prostate-specific antigen (PSA), a substance found only in human semen, using rocket immunoelectrophoresis, and inspected microscopically for presence of sperm. Sixty-eight baseline ejaculate samples collected from the inside of the first study condom by couples who subsequently experienced a condom failure averaged 13.4 microg PSA per swab and 79% of the samples averaged one or more sperm per high power field (hpf). Seventy-nine postcoital vaginal samples obtained after a condom break averaged 5.7 microg PSA per swab and only 38% averaged one or more sperm per hpf. The PSA results indicated a 50% reduction in semen exposure compared to baseline levels (p = 0.0001). Seventeen samples obtained after a condom slip-off averaged 2.5 microg PSA per swab and none of the samples averaged one or more sperm per hpf. The PSA results indicated an 80% reduction in semen exposure compared to baseline levels (p = 0.0001). Our results suggest that even condoms that fail reduce the risk of pregnancy and the transmission of sexually transmitted disease compared to unprotected intercourse. We also used PSA results to adjust a model designed to predict consistent-use pregnancy rates from condom breakage and slippage data.

Modeling population exposures to outdoor sources of hazardous air pollutants.

PubMed

Ozkaynak, Halûk; Palma, Ted; Touma, Jawad S; Thurman, James

2008-01-01

Accurate assessment of human exposures is an important part of environmental health effects research. However, most air pollution epidemiology studies rely upon imperfect surrogates of personal exposures, such as information based on available central-site outdoor concentration monitoring or modeling data. In this paper, we examine the limitations of using outdoor concentration predictions instead of modeled personal exposures for over 30 gaseous and particulate hazardous air pollutants (HAPs) in the US. The analysis uses the results from an air quality dispersion model (the ASPEN or Assessment System for Population Exposure Nationwide model) and an inhalation exposure model (the HAPEM or Hazardous Air Pollutant Exposure Model, Version 5), applied by the US. Environmental protection Agency during the 1999 National Air Toxic Assessment (NATA) in the US. Our results show that the total predicted chronic exposure concentrations of outdoor HAPs from all sources are lower than the modeled ambient concentrations by about 20% on average for most gaseous HAPs and by about 60% on average for most particulate HAPs (mainly, due to the exclusion of indoor sources from our modeling analysis and lower infiltration of particles indoors). On the other hand, the HAPEM/ASPEN concentration ratio averages for onroad mobile source exposures were found to be greater than 1 (around 1.20) for most mobile-source related HAPs (e.g. 1, 3-butadiene, acetaldehyde, benzene, formaldehyde) reflecting the importance of near-roadway and commuting environments on personal exposures to HAPs. The distribution of the ratios of personal to ambient concentrations was found to be skewed for a number of the VOCs and reactive HAPs associated with major source emissions, indicating the importance of personal mobility factors. We conclude that the increase in personal exposures from the corresponding predicted ambient levels tends to occur near locations where there are either major emission sources of HAPs or when individuals are exposed to either on- or nonroad sources of HAPs during their daily activities. These findings underscore the importance of applying exposure-modeling methods, which incorporate information on time-activity, commuting, and exposure factors data, for the purposes of assigning exposures in air pollution health studies.

SU-E-I-71: KVp Dependence of Transmitted Exposure for a Radiography Unit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Y; Lynch, D; So, J

2014-06-01

Purpose: To investigate the kVp dependence of the transmitted exposure for a radiography x-ray unit. Methods: The study used a GE DiscoveryTM XR656 DR unit, a 30 (L) × 30 (W) × 25 cm thick Lucite phantom, two anthropomorphic phantoms (an Alderson RS-310 chest phantom and a 3M skull phantom), an Unfors detector, and a Radcal 10x9-6 ion chamber. We measured the entrance exposure and transmitted exposure of each phantom at 60, 70, 80, 90, 100, 110, 120 kVp for mAs range from 2.5 to 200 mAs, without any additional filter. The FOV is 30×30 cm for the Lucite andmore » chest phantom (AP view), and 20×20 cm for skull phantom (Lateral view). The transmitted exposure was measured at the phantom center of the x-ray exit side. For chest phantom, the transmitted exposures at 3 inch upper right and upper left from the center were also measured. We also checked the reproducibility and accuracy of the DR unit. Results: For each phantom, at every kVp and mAs setting, the transmitted exposure per mAs was calculated and normalized by the relative entrance exposure; the averaged transmitted exposure per mAs at each specific kVp was then determined. For chest phantom, the mean transmitted exposure per mAs was the average of three exit locations. The averaged transmitted exposure per mAs was fit as a power function of kVp. The result showed the transmitted exposure per mAs was approximately proportional to third power of the kVp for two anthropomorphic phantoms and forth power of the kVp for the Lucite phantom. Conclusion: The traditional assumption of fifth power kVp dependence to the transmitted exposure is inaccurate. At the normal radiography kVp range, the transmitted exposure is approximately proportional to third power of the kVp for a typical patient and up to forth power of the kVp for a large patient.« less

Radiation safety audit of a high volume Nuclear Medicine Department

PubMed Central

Jha, Ashish Kumar; Singh, Abhijith Mohan; Shetye, Bhakti; Shah, Sneha; Agrawal, Archi; Purandare, Nilendu Chandrakant; Monteiro, Priya; Rangarajan, Venkatesh

2014-01-01

Introduction: Professional radiation exposure cannot be avoided in nuclear medicine practices. It can only be minimized up to some extent by implementing good work practices. Aim and Objectives: The aim of our study was to audit the professional radiation exposure and exposure rate of radiation worker working in and around Department of nuclear medicine and molecular imaging, Tata Memorial Hospital. Materials and Methods: We calculated the total number of nuclear medicine and positron emission tomography/computed tomography (PET/CT) procedures performed in our department and the radiation exposure to the radiation professionals from year 2009 to 2012. Results: We performed an average of 6478 PET/CT scans and 3856 nuclear medicine scans/year from January 2009 to December 2012. The average annual whole body radiation exposure to nuclear medicine physician, technologist and nursing staff are 1.74 mSv, 2.93 mSv and 4.03 mSv respectively. Conclusion: Efficient management and deployment of personnel is of utmost importance to optimize radiation exposure in a high volume nuclear medicine setup in order to work without anxiety of high radiation exposure. PMID:25400361

Exposure of bakery and pastry apprentices to airborne flour dust using PM2.5 and PM10 personal samplers.

PubMed

Mounier-Geyssant, Estelle; Barthélemy, Jean-François; Mouchot, Lory; Paris, Christophe; Zmirou-Navier, Denis

2007-11-01

This study describes exposure levels of bakery and pastry apprentices to flour dust, a known risk factor of occupational asthma. Questionnaires on work activity were completed by 286 students. Among them, 34 performed a series of two personal exposure measurements using a PM2.5 and PM10 personal sampler during a complete work shift, one during a cold ("winter") period, and the other during a hot ("summer") period. Bakery apprentices experience greater average PM2.5 and PM10 exposures than pastry apprentices (p < 0.006). Exposure values for both particulate fractions are greater in winter (average PM10 values among bakers = 1.10 mg.m-3 [standard deviation: 0.83]) than in summer (0.63 mg.m-3 [0.36]). While complying with current European occupational limit values, these exposures exceed the ACGIH recommendations set to prevent sensitization to flour dust (0.5 mg.m-3). Over half the facilities had no ventilation system. Young bakery apprentices incur substantial exposure to known airways allergens, a situation that might elicit early induction of airways inflammation.

Middle and High School Students’ Exposure to Alcohol- and Smoking-Related Media: A Pilot Study Using Ecological Momentary Assessment

PubMed Central

Scharf, Deborah M.; Martino, Steven C.; Setodji, Claude M.; Staplefoote, B. Lynette; Shadel, William G.

2013-01-01

The goals of this study were to assess the feasibility of using Ecological Momentary Assessment (EMA) to measure adolescents’ exposure to alcohol and smoking-related media. A sample of 20 middle and high school students completed a two-week EMA protocol in which they monitored exposures to alcohol and smoking-related media. Results showed that adolescents were highly compliant with the study protocol. A total of 255 exposures to alcohol (67%) and smoking (33%) were captured, representing an average of 8.50 (5.82) alcohol-related media exposures and 4.25 (SD = 3.67) smoking-related media exposures and an average of per participant during the study period. Exposures tended to occur in the afternoon (52% alcohol; 54% smoking), at point of sale (44% alcohol; 65% smoking) and on days leading up to the weekend (57% alcohol; 57% smoking). Exposures were also likely in the presence of family (69% alcohol; 56% smoking). Overall, results of this small pilot provide preliminary evidence that EMA is a useful tool for tracking and characterizing middle and high school students’ real-world exposures to alcohol and smoking-related media. Future studies may suggest mechanisms by which media exposures lead to youth uptake of drinking and smoking behaviors. PMID:23772763

Evaluation of Potential Exposure to Metals in Laundered Shop Towels

PubMed Central

Greenberg, Grace; Beck, Barbara D.

2013-01-01

We reported in 2003 that exposure to metals on laundered shop towels (LSTs) could exceed toxicity criteria. New data from LSTs used by workers in North America document the continued presence of metals in freshly laundered towels. We assessed potential exposure to metals based on concentrations of metals on the LSTs, estimates of LST usage by employees, and the transfer of metals from LST-to-hand, hand-to-mouth, and LST-to-lip, under average- or high-exposure scenarios. Exposure estimates were compared to toxicity criteria. Under an average-exposure scenario (excluding metals' data outliers), exceedances of the California Environmental Protection Agency, U.S. Environmental Protection Agency, and the Agency for Toxic Substances and Disease Registry toxicity criteria may occur for aluminum, cadmium, cobalt, copper, iron, and lead. Calculated intakes for these metals were up to more than 400-fold higher (lead) than their respective toxicity criterion. For the high-exposure scenario, additional exceedances may occur, and high-exposure intakes were up to 1,170-fold higher (lead) than their respective toxicity criterion. A sensitivity analysis indicated that alternate plausible assumptions could increase or decrease the magnitude of exceedances, but were unlikely to eliminate certain exceedances, particularly for lead. PMID:24453472

Football match spectator sound exposure and effect on hearing: a pretest-post-test study.

PubMed

Swanepoel, De Wet; Hall, James W

2010-03-30

To determine (i) noise exposure levels of spectators at a FIFA 2010 designated training stadium during a premier soccer league match; and (ii) changes in auditory functioning after the match. This was a one-group pretest-post-test design of football spectators attending a premier soccer league match at a designated FIFA 2010 training stadium in Gauteng, South Africa. Individual spectator noise exposure for the duration of the football match and post-match changes in hearing thresholds were measured with pure-tone audiometry, and cochlear functioning was measured with distortion product oto-acoustic emissions (DPOAEs). The average sound exposure level during the match was 100.5 LAeq (dBA), with peak intensities averaging 140.4 dB(C). A significant (p=0.005) deterioration of post-match hearing thresholds was evident at 2 000 Hz, and post-match DPOAE amplitudes were significantly reduced at 1,266, 3,163 and 5,063 Hz (p=0.011, 0.019, 0.013, respectively). Exposure levels exceeded limits of permissible average and peak sound levels. Significant changes in post-match hearing thresholds and cochlear responsiveness highlight the possible risk for noise-induced hearing loss. Public awareness and personal hearing protection should be prioritized as preventive measures.

Minireview on the toxicity of dietary acrylamide.

PubMed

Parzefall, Wolfram

2008-04-01

Acrylamide is a commodity chemical with many industrial and laboratory uses. It is also formed from carbohydrate and amino acid containing food by heating (primarily in fried potato products, bread, coffee). Neurotoxicity was detected as the primary toxic effect after occupational exposure. In rats and mice AA is toxic for reproduction and development and to male germ cells, is genotoxic through a reactive metabolite, glycidamide, and carcinogenic to several organs. Epidemiological studies did not point to an association between either occupational or dietary exposure and an excess of cancer incidence. Health risks of the general population are based on an average exposure to 1 microg/kg bw/day increasing for high consumers to 4 microg/kg bw/day. For average consumers a margin of exposure of 200 for neurotoxicity can be regarded as sufficiently protective. However, a margin of 300 for carcinogenic risks appears not sufficient when applying a precautionary principle. This is also illustrated when the benchmark dose lower confidence limit for cancer is divided by an uncertainty factor of 300, which arrives at a tolerable daily intake of 1 microg/kg bw/day, and thus is in the range of average consumption. Further measures to minimize acrylamide formation in food should therefore be explored to reduce human exposure.

Nicotine and carbon monoxide exposure from inhalation of cigarillo smoke.

PubMed

Koszowski, Bartosz; Rosenberry, Zachary R; Kanu, Alieu; Viray, Lauren C; Potts, Jennifer L; Pickworth, Wallace B

2015-12-01

There has been an increase in the use of cigarillos in the US. People who smoke cigarillos typically also regularly smoke cigarettes (dual users). We compared puffing topography, biomarkers of acute exposure [exhaled carbon monoxide (COex) and plasma nicotine] and physiologic effects from usual brand cigarette and Black & Mild cigarillo smoking in dual users (N=23) in two laboratory sessions. Participants (21 men) smoked an average of 17.5cigarettes/day. Cigarillo consumption varied widely from as few as 1/week to daily. Participants were highly nicotine dependent (average FTND score: 6.3). There were statistically significant differences in smoking behavior between cigarette and cigarillo smoking in time to smoke, number of puffs, and total puff volume (all P<0.001). Average puff duration, interpuff interval average puff volume, and puff velocity did not differ between cigarettes and cigarillos. Nicotine boost was similar after both cigarettes and cigarillos. COex boost was significantly greater after cigarillo smoking compared to cigarette smoking (P<0.001). The smoking pattern and exposure profile indicate that dual users inhale cigarillo smoke just as they inhale cigarette smoke thereby exposing themselves to considerable amounts of nicotine and other components of tobacco smoke. COex exposure results imply that cigarillo smoking may be associated with higher exposure to smoke-delivered volatile components of mainstream cigarillo smoke including carcinogens when compared to cigarettes. The findings that cigarillos and cigarettes are smoked similarly in dual users are relevant to health and regulatory considerations on cigar products. Copyright © 2015 Elsevier Inc. All rights reserved.

41 CFR 50-204.22 - Exposure to airborne radioactive material.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 1 2010-07-01 2010-07-01 true Exposure to airborne... FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.22 Exposure to airborne radioactive material. (a) No..., within a restricted area, to be exposed to airborne radioactive material in an average concentration in...

Exposure of bed bugs to metarhizium anisopliae, and the effect of defensive secretions on fungal growth in vitro

USDA-ARS?s Scientific Manuscript database

Bed bugs Cimex lectularius were treated with conidia of the entomopathogenic fungus Metarhizium anisopliae by topical, spray, and contact exposure. One week post-exposure, inconsistent mortalities were observed, averaging 30% across all treatment groups and replicates. Microscopic examination of top...

EXPOSURE RECONSTRUCTION FOR REDUCING UNCERTAINTY IN RISK ASSESSMENT: EXAMPLE USING MTBE BIOMARKERS AND SIMPLE PHARMACOKINETIC MODEL

EPA Science Inventory

Adverse health risks from environmental agents are generally related to average (long term) exposures. We used results from a series of controlled human exposure tests and classical first order rate kinetics calculations to estimate how well spot measurements of methyl tertiary ...

CONCENTRATION - DURATION RELATIONSHIPS FOR NON-CANCER HEALTH EFFECTS OF EXPOSURE TO HAZARDOUS AIR POLLUTANTS.

EPA Science Inventory

EPA is charged with assessing the risks of both acute and chronic exposures to hazardous air pollutants
(HAPs). The emissions from sources of HAPs are often characterized as temporally-averaged values,
however, patterns of exposure not captured in such measures may infl...

Using a physiologically based pharmacokinetic model to link urinary biomarker concentrations to dietary exposure of perchlorate

EPA Science Inventory

Exposure to perchlorate is widespread in the United States and many studies have attempted to character the perchlorate exposure by estimating the average daily intakes of perchlorate. These approaches provided population-based estimates, but did not provide individual-level exp...

Dietary exposure of Hong Kong secondary school students to total mercury and methylmercury from fish intake.

PubMed

Tang, Anna Shiu Ping; Kwong, Ka Ping; Chung, Stephen Wai Cheung; Ho, Yuk Yin; Xiao, Ying

2009-01-01

Fish is the main source of dietary exposure to methylmercury (MeHg), which is a public health concern owing to its potential neurotoxicity. To evaluate the public health risk, this study estimated the total mercury (tHg) and MeHg exposure from fish intake in Hong Kong secondary school students. Median tHg and MeHg concentrations of 280 samples purchased from different commercial outlets (covering 89 species of whole fish and three types of canned tuna), together with the local food consumption data of secondary school students obtained by semi-quantitative food frequency questionnaire in 2000, were used to estimate dietary exposure from fish intake for the average and high consumer (95th percentile exposure). For tHg, the median concentration was 63 µg kg(-1) (range 3-1370 µg kg(-1)) and estimated exposures ranged 0.5-0.6 µg kg(-1) body weight (bw) week(-1) for an average consumer and 1.6-1.9 µg kg(-1) bw week(-1) for a high consumer. For MeHg, median concentration was 48 µg kg(-1) (range 3-1010 µg kg(-1)) and estimated dietary exposures were 0.4-0.5 µg kg(-1) bw week(-1) for an average consumer and 1.2-1.4 µg kg(-1) bw week(-1) for a high consumer. These values are below the respective provisional tolerable weekly intake (PTWI) established by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA). The health risk is greater for high consumers since MeHg exposures may approach or exceed the PTWI when other dietary sources are taken into account.

National-scale exposure prediction for long-term concentrations of particulate matter and nitrogen dioxide in South Korea.

PubMed

Kim, Sun-Young; Song, Insang

2017-07-01

The limited spatial coverage of the air pollution data available from regulatory air quality monitoring networks hampers national-scale epidemiological studies of air pollution. The present study aimed to develop a national-scale exposure prediction model for estimating annual average concentrations of PM 10 and NO 2 at residences in South Korea using regulatory monitoring data for 2010. Using hourly measurements of PM 10 and NO 2 at 277 regulatory monitoring sites, we calculated the annual average concentrations at each site. We also computed 322 geographic variables in order to represent plausible local and regional pollution sources. Using these data, we developed universal kriging models, including three summary predictors estimated by partial least squares (PLS). The model performance was evaluated with fivefold cross-validation. In sensitivity analyses, we compared our approach with two alternative approaches, which added regional interactions and replaced the PLS predictors with up to ten selected variables. Finally, we predicted the annual average concentrations of PM 10 and NO 2 at 83,463 centroids of residential census output areas in South Korea to investigate the population exposure to these pollutants and to compare the exposure levels between monitored and unmonitored areas. The means of the annual average concentrations of PM 10 and NO 2 for 2010, across regulatory monitoring sites in South Korea, were 51.63 μg/m3 (SD = 8.58) and 25.64 ppb (11.05), respectively. The universal kriging exposure prediction models yielded cross-validated R 2 s of 0.45 and 0.82 for PM 10 and NO 2 , respectively. Compared to our model, the two alternative approaches gave consistent or worse performances. Population exposure levels in unmonitored areas were lower than in monitored areas. This is the first study that focused on developing a national-scale point wise exposure prediction approach in South Korea, which will allow national exposure assessments and epidemiological research to answer policy-related questions and to draw comparisons among different countries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Journey-time exposure to particulate air pollution

NASA Astrophysics Data System (ADS)

Gulliver, John; Briggs, David J.

Journey-time exposures to particulate air pollution were investigated in Leicester, UK, between January and March 2005. Samples of TSP, PM 10, PM 2.5, and PM 1 were simultaneously collected using light scattering devices whilst journeys were made by walking an in-car. Over a period of two months, 33 pairs of walking and in-car measurements were collected along two circular routes. Average exposures while walking were seen to be higher than those found in-car for each of the particle fractions: average walking to in-car ratios were 1.2 (± 0.6), 1.5 (± 0.6), 1.3 (± 0.6), and 1.4 (± 0.6) μg m -3 for coarse (TSP-PM 10), intermediate (PM 10-PM 2.5), fine (PM 2.5-PM 1), and very fine particles (PM 1), respectively. Correlations between walking and in-car exposures were seen to be weak for coarse particles ( r=0.10, p=0.58), moderate for the intermediate particles ( r=0.49, p<0.01) but strong for fine ( r=0.89, p<0.01) and very fine ( r=0.90, P<0.01) particles. PM 10 exposures while walking were on average 70% higher than a nearby roadside fixed-site monitor whilst in-car exposures were 25% higher than the same fixed-site monitor. Particles with an aerodynamic diameter of less than 2.5 μm were seen to be highly correlated between walking and in-car particle exposures and a rural fixed-site monitor about 30 km south of Leicester.

Cycling exercise classes may be bad for your (hearing) health.

PubMed

Sinha, Sumi; Kozin, Elliott D; Naunheim, Matthew R; Barber, Samuel R; Wong, Kevin; Katz, Leanna W; Otero, Tiffany M N; Stefanov-Wagner, Ishmael J M; Remenschneider, Aaron K

2017-08-01

1) Determine feasibility of smartphone-based mobile technology to measure noise exposure; and 2) measure noise exposure in exercise spin classes. Observational Study. The SoundMeter Pro app (Faber Acoustical, Salt Lake City, UT) was installed and calibrated on iPhone and iPod devices in an audiology chamber using an external sound level meter to within 2 dBA of accuracy. Recording devices were placed in the bike cupholders of participants attending spin classes in Boston, Massachusetts (n = 17) and used to measure sound level (A-weighted) and noise dosimetry during exercise according to National Institute for Occupational Safety and Health (NIOSH) guidelines. The average length of exposure was 48.9 ± 1.2 (standard error of the mean) minutes per class. Maximum sound recorded among 17 random classes was 116.7 dBA, which was below the NIOSH instantaneous exposure guideline of 140 dBA. An average of 31.6 ± 3.8 minutes were spent at >100 dBA. This exceeds NIOSH recommendations of 15 minutes of exposure or less at 100 dBA per day. Average noise exposure for one 45-minute class was 8.95 ± 1.2 times the recommended noise exposure dose for an 8-hour workday. Preliminary data shows that randomly sampled cycling classes may have high noise levels with a potential for noise-induced hearing loss. Mobile dosimetry technology may enable users to self-monitor risk to their hearing and actively engage in noise protection measures. NA Laryngoscope, 127:1873-1877, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Bulk chlorine uptake by polyamide active layers of thin-film composite membranes upon exposure to free chlorine-kinetics, mechanisms, and modeling.

PubMed

Powell, Joshua; Luh, Jeanne; Coronell, Orlando

2014-01-01

We studied the volume-averaged chlorine (Cl) uptake into the bulk region of the aromatic polyamide active layer of a reverse osmosis membrane upon exposure to free chlorine. Volume-averaged measurements were obtained using Rutherford backscattering spectrometry with samples prepared at a range of free chlorine concentrations, exposure times, and mixing, rinsing, and pH conditions. Our volume-averaged measurements complement previous studies that have quantified Cl uptake at the active layer surface (top ≈ 7 nm) and advance the mechanistic understanding of Cl uptake by aromatic polyamide active layers. Our results show that surface Cl uptake is representative of and underestimates volume-averaged Cl uptake under acidic conditions and alkaline conditions, respectively. Our results also support that (i) under acidic conditions, N-chlorination followed by Orton rearrangement is the dominant Cl uptake mechanism with N-chlorination as the rate-limiting step; (ii) under alkaline conditions, N-chlorination and dechlorination of N-chlorinated amide links by hydroxyl ion are the two dominant processes; and (iii) under neutral pH conditions, the rates of N-chlorination and Orton rearrangement are comparable. We propose a kinetic model that satisfactorily describes Cl uptake under acidic and alkaline conditions, with the largest discrepancies between model and experiment occurring under alkaline conditions at relatively high chlorine exposures.

Silicosis among gold miners: exposure--response analyses and risk assessment.

PubMed

Steenland, K; Brown, D

1995-10-01

This study sought to estimate the risk of silicosis by cumulative exposure-years in a cohort of miners exposed to silica, as well as the lifetime risk of silicosis under the current Occupational Safety and Health Administration (OSHA) standard (0.09 mg/m3). In a cohort study of 3330 gold miners who worked at least 1 year underground from 1940 to 1965 (average 9 years) and were exposed to a median silica level of 0.05 mg/m3 (0.15 mg/m3 for those hired before 1930), 170 cases of silicosis were determined from either death certificates or two cross-sectional radiographic surveys. The risk of silicosis was less than 1% with a cumulative exposure under 0.5 mg/m3-years, increasing to 68% to 84% for the highest cumulative exposure category of more than 4 mg/m3-years. Cumulative exposure was the best predictor of disease, followed by duration of exposure and average exposure. After adjustment for competing risks of death, a 45-year exposure under the current OSHA standard would lead to a lifetime risk of silicosis of 35% to 47%. Almost 2 million US workers are currently exposed to silica. Our results add to a small but increasing body of literature that suggests that the current OSHA silica exposure level is unacceptably high.

ERROR IN ANNUAL AVERAGE DUE TO USE OF LESS THAN EVERYDAY MEASUREMENTS

EPA Science Inventory

Long term averages of the concentration of PM mass and components are of interest for determining compliance with annual averages, for developing exposure surrogated for cross-sectional epidemiologic studies of the long-term of PM, and for determination of aerosol sources by chem...

Solar exposure and residential geographic history in relation to exfoliation syndrome in the United States and Israel.

PubMed

Pasquale, Louis R; Jiwani, Aliya Z; Zehavi-Dorin, Tzukit; Majd, Arow; Rhee, Douglas J; Chen, Teresa; Turalba, Angela; Shen, Lucy; Brauner, Stacey; Grosskreutz, Cynthia; Gardiner, Matthew; Chen, Sherleen; Borboli-Gerogiannis, Sheila; Greenstein, Scott H; Chang, Kenneth; Ritch, Robert; Loomis, Stephanie; Kang, Jae H; Wiggs, Janey L; Levkovitch-Verbin, Hani

2014-12-01

Residential (geographic) history and extent of solar exposure may be important risk factors for exfoliation syndrome (XFS) but, to our knowledge, detailed lifetime solar exposure has not been previously evaluated in XFS. To assess the relation between residential history, solar exposure, and XFS. This clinic-based case-control study was conducted in the United States and Israel. It involved XFS cases and control individuals (all ≥ 60-year-old white individuals) enrolled from 2010 to 2012 (United States: 118 cases and 106 control participants; Israel: 67 cases and 72 control participants). Weighted lifetime average latitude of residence and average number of hours per week spent outdoors as determined by validated questionnaires. In multivariable analyses, each degree of weighted lifetime average residential latitude away from the equator was associated with 11% increased odds of XFS (pooled odds ratio [OR], 1.11; 95% CI, 1.05-1.17; P < .001). Furthermore, every hour per week spent outdoors during the summer, averaged over a lifetime, was associated with 4% increased odds of XFS (pooled OR, 1.04; 95% CI, 1.00-1.07; P = .03). For every 1% of average lifetime summer time between 10 am and 4 pm that sunglasses were worn, the odds of XFS decreased by 2% (OR, 0.98; 95% CI, 0.97-0.99; P < .001) in the United States but not in Israel (OR, 1.00; 95% CI, 0.99-1.01; P = .92; P for heterogeneity = .005). In the United States, after controlling for important environmental covariates, history of work over water or snow was associated with increased odds of XFS (OR, 3.86; 95% CI, 1.36-10.9); in Israel, there were too few people with such history for analysis. We did not identify an association between brimmed hat wear and XFS (P > .57). Lifetime outdoor activities may contribute to XFS. The association with work over snow or water and the lack of association with brimmed hat wear suggests that ocular exposure to light from reflective surfaces may be an important type of exposure in XFS etiology.

Development and validation of a highly sensitive gas chromatographic-mass spectrometric screening method for the simultaneous determination of nanogram levels of fentanyl, sufentanil and alfentanil in air and surface contamination wipes.

PubMed

Van Nimmen, Nadine F J; Veulemans, Hendrik A F

2004-05-07

A highly sensitive gas chromatographic-mass spectrometric (GC-MS) analytical method for the determination of the opioid narcotics fentanyl, alfentanil, and sufentanil in industrial hygiene personal air samples and surface contamination wipes was developed and comprehensively validated. Sample preparation involved a single step extraction of the samples with methanol, fortified with a fixed amount of the penta-deuterated analogues of the opioid narcotics as internal standard. The GC-MS analytical procedure using selected ion monitoring (SIM) was shown to be highly selective. Linearity was shown for levels of extracted wipe and air samples corresponding to at least 0.1-2 times their surface contamination limit (SCL) and accordingly to 0.1-2 times their time weighted average occupational exposure limit (OEL-TWA) based on a full shift 9601 air sample. Extraction recoveries were determined for spiked air samples and surface wipes and were found to be quantitative for both sampling media in the entire range studied. The air sampling method's limit of detection (LOD) was determined to be 0.4 ng per sample for fentanyl and sufentanil and 1.6 ng per sample for alfentanil, corresponding to less than 1% of their individual OEL for a full shift air sample (9601). The limit of quantification (LOQ) was found to be 1.4, 1.2, and 5.0 ng per filter for fentanyl, sufentanil, and alfentanil, respectively. The wipe sampling method had LODs of 4 ng per wipe for fentanyl and sufentanil and 16 ng per wipe for alfentanil and LOQs of respectively, 14, 12, and 50 ng per wipe. The analytical intra-assay precision of the air sampling and wipe sampling method, defined as the coefficient of variation on the analytical result of six replicate spiked media was below 10 and 5%, respectively, for all opioids at all spike levels. Accuracy expressed as relative error was determined to be below 10%, except for alfentanil at the lowest spike level (-13.1%). The stability of the opioids during simulated air sampling was investigated. For fentanyl and sufentanil a quantitative recovery was observed at all spike levels, while for alfentanil recoveries ranged from 60.3 to 85.4%. When spiked air samples were stored at ambient temperature and at -15 degrees C quantitative recovery was found for fentanyl and sufentanil after 7 and 14 days. For alfentanil a slight loss seemed to occur upon storage during 7 days, being more explicit after 14 days. Ambient storage of spiked wipes seemed to lead to significant losses of all opioids studied, yielding recoveries of 37.7-88.3%. Upon storage of similar wipes at -15 degrees C a significantly higher recovery was found ranging from 77.3 to 88.3%. The developed analytical and sampling procedures have been recently applied in an explorative field study of which the results of surface contamination wipe sampling are presented in this paper. To our knowledge, this is the first study addressing the development and validation of analytical procedures for the assessment of external occupational exposure to potent opioid narcotics.

Retrospective exposure assessment to airborne asbestos among power industry workers

PubMed Central

2010-01-01

Background A method of individually assessing former exposure to asbestos fibres is a precondition of risk-differentiated health surveillance. The main aims of our study were to assess former levels of airborne asbestos exposure in the power industry in Germany and to propose a basic strategy for health surveillance and the early detection of asbestos related diseases. Methods Between March 2002 and the end of 2006, we conducted a retrospective questionnaire based survey of occupational tasks and exposures with airborne asbestos fibres in a cohort of 8632 formerly asbestos exposed power industry workers. The data on exposure and occupation were entered into a specially designed computer programme, based on ambient monitoring of airborne asbestos fibre concentrations. The cumulative asbestos exposure was expressed as the product of the eight-hour time weighted average and the total duration of exposure in fibre years (fibres/cubic centimetre-years). Results Data of 7775 (90% of the total) participants working in installations for power generation, power distribution or gas supply could be evaluated. The power generation group (n = 5284) had a mean age of 56 years, were exposed for 20 years and had an average cumulative asbestos exposure of 42 fibre years. The occupational group of "metalworkers" (n = 1600) had the highest mean value of 79 fibre years. The corresponding results for the power distribution group (n = 2491) were a mean age of 45 years, a mean exposure duration of 12 years and an average cumulative asbestos exposure of only 2.5 fibre years. The gas supply workers (n = 512) had a mean age of 54 years and a mean duration of exposure of 15 years. Conclusions While the surveyed cohort as a whole was heavily exposed to asbestos dust, the power distribution group had a mean cumulative exposure of only 6% of that found in the power generation group. Based on the presented data, risk-differentiated disease surveillance focusing on metalworkers and electricians from the power generating industry seems justified. That combined with a sensitive examination technique would allow detecting asbestos related diseases early and efficiently. PMID:20579364

Detailed exposure assessment of dietary furan for infants consuming commercially jarred complementary food based on data from the DONALD study.

PubMed

Lachenmeier, Dirk W; Maser, Elena; Kuballa, Thomas; Reusch, Helmut; Kersting, Mathilde; Alexy, Ute

2012-07-01

Furan is a possible human carcinogen regularly occurring in commercially jarred complementary foods. This paper will provide a detailed exposure assessment for babies consuming these foods considering different intake scenarios. The occurrence data on furan in complementary foods were based on our own headspace-gas chromatography/mass spectrometry (HS-GC/MS) analytical results (n = 286). The average furan content in meals and menus was between 20 and 30 µg kg(-1), which is in excellent agreement with results from other European countries. Using measured food consumption data from the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study, the average exposures for consumers of commercially jarred foods ranged between 182 and 688 ng kg(-1) bw day(-1), with a worst case scenario for P95 consumers ranging between 351 and 1066 ng kg(-1) bw day(-1). The exposure data were then used to characterize risk using the margin of exposure method based on a benchmark dose lower confidence limit for a 10% response (BMDL10) of 1.28 mg kg(-1) bw day(-1) for hepatocellular tumours in rats. The margin of exposures (MOEs) were below the threshold of 10 000, which is often used to define public health risks, in all scenarios, ranging between 7022 and 1861 for average consumers and between 3642 and 1200 for the P95 consumers. Mitigative measures to avoid furan in complementary foods should be of high priority for risk management. © 2010 Blackwell Publishing Ltd.

Estimates of Ethanol Exposure in Children from Food not Labeled as Alcohol-Containing.

PubMed

Gorgus, Eva; Hittinger, Maike; Schrenk, Dieter

2016-09-01

Ethanol is widely used in herbal medicines, e.g., for children. Furthermore, alcohol is a constituent of fermented food such as bread or yogurt and "non-fermented" food such as fruit juices. At the same time, exposure to very low levels of ethanol in children is discussed as possibly having adverse effects on psychomotoric functions. Here, we have analyzed alcohol levels in different food products from the German market. It was found that orange, apple and grape juice contain substantial amounts of ethanol (up to 0.77 g/L). Furthermore, certain packed bakery products such as burger rolls or sweet milk rolls contained more than 1.2 g ethanol/100 g. We designed a scenario for average ethanol exposure by a 6-year-old child. Consumption data for the "categories" bananas, bread and bakery products and apple juice were derived from US and German surveys. An average daily exposure of 10.3 mg ethanol/kg body weight (b.w.) was estimated. If a high (acute) consumption level was assumed for one of the "categories," exposure rose to 12.5-23.3 mg/kg b.w. This amount is almost 2-fold (average) or up to 4-fold (high) higher than the lowest exposure from herbal medicines (6 mg/kg b.w.) suggested to require warning hints for the use in children. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Conjugal Parkinsonism and Parkinson Disease: A Case Series with Environmental Risk Factor Analysis

PubMed Central

Sterling, Callen; Racette, Brad A.

2009-01-01

PD occurring in married couples, “conjugal PD” represents a unique opportunity to study environmental risk factors for PD due to the shared environment. This retrospective study of non-related married individuals who both presented to the Washington University Movement Disorders Center between 1994 and 2005 investigated the clinical presentation, therapy response, and disease course in conjugal PD subjects. In addition, an occupational, residential, and environmental survey was administered to elucidate potential shared environmental risk factors. Eighteen married subjects had a clinical picture suggestive of idiopathic Parkinson disease. Average age of motor symptom onset was 66.1 (±6.22) years in women, 63.4 (±7.87) years in men. Subjects cohabitated an average of 39.9 years prior to motor symptom onset in the first affected spouse and an average of nine years elapsed prior to symptom onset in their partner. Disease course in conjugal pairs varied substantially. Seventeen out of eighteen subjects reported at least one environmental exposure of interest. Concordant exposures were residential, non-occupational pesticide and heavy metal exposure, each reported by 77.8% (7/9) of couples. Multiple exposures were reported by 88.9% (16/18) of subjects, most often residential agricultural chemical and heavy metal in combination. This case series of conjugal PD suggests that combined residential exposures may be important in the pathogenesis of idiopathic PD. Larger conjugal PD studies may permit stratification of concordant environmental exposures to determine dose responsiveness and relative contributions to PD risk. PMID:19818671

Dietary exposure to chloropropanols of secondary school students in Hong Kong.

PubMed

Yau, J C W; Kwong, K P; Chung, S W C; Ho, Y Y; Xiao, Y

2008-01-01

This paper reports levels of 3-monochloropropan-1,2-diol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) in a wide range of food items and estimates their dietary exposure for secondary school students in Hong Kong. Dietary exposure to chloropropanols was estimated using local food consumption data obtained from secondary school students in 2000 and the concentrations of 3-MCPD and 1,3-DCP in food samples taken from the local market. The dietary exposure to 3-MCPD for an average secondary school student consumer was estimated to be 0.063-0.150 µg kg(-1) body weight (bw) day(-1), whilst that for the high consumer was 0.152-0.300 µg kg(-1) bw day(-1). Both estimates fell below the provisional maximum tolerable daily intake of 2 µg kg(-1) bw established by the Joint Expert Committee on Food Additives (JECFA) and amounted to less than 20% of this safety reference value. The dietary exposure to 1,3-DCP for an average secondary school student consumer was estimated to be 0.003-0.019 µg kg(-1) bw day(-1), whilst that for the high consumer was 0.009-0.040 µg kg(-1) bw day(-1). The resulting margins of exposures were of low concern for human health. It could be concluded that both the average and high secondary school student consumers were unlikely to experience major toxicological effects of 3-MCPD and 1,3-DCP.

Estimated radiation exposure of German commercial airline cabin crew in the years 1960-2003 modeled using dose registry data for 2004-2015.

PubMed

Wollschläger, Daniel; Hammer, Gaël Paul; Schafft, Thomas; Dreger, Steffen; Blettner, Maria; Zeeb, Hajo

2018-05-01

Exposure to ionizing radiation of cosmic origin is an occupational risk factor in commercial aircrew. In a historic cohort of 26,774 German aircrew, radiation exposure was previously estimated only for cockpit crew using a job-exposure matrix (JEM). Here, a new method for retrospectively estimating cabin crew dose is developed. The German Federal Radiation Registry (SSR) documents individual monthly effective doses for all aircrew. SSR-provided doses on 12,941 aircrew from 2004 to 2015 were used to model cabin crew dose as a function of age, sex, job category, solar activity, and male pilots' dose; the mean annual effective dose was 2.25 mSv (range 0.01-6.39 mSv). In addition to an inverse association with solar activity, exposure followed age- and sex-dependent patterns related to individual career development and life phases. JEM-derived annual cockpit crew doses agreed with SSR-provided doses for 2004 (correlation 0.90, 0.40 mSv root mean squared error), while the estimated average annual effective dose for cabin crew had a prediction error of 0.16 mSv, equaling 7.2% of average annual dose. Past average annual cabin crew dose can be modeled by exploiting systematic external influences as well as individual behavioral determinants of radiation exposure, thereby enabling future dose-response analyses of the full aircrew cohort including measurement error information.

Modeling long-term effects attributed to nitrogen dioxide (NO2) and sulfur dioxide (SO2) exposure on asthma morbidity in a nationwide cohort in Israel.

PubMed

Greenberg, N; Carel, R S; Derazne, E; Tiktinsky, A; Tzur, D; Portnov, B A

2017-01-01

Studies have provided extensive documentation that acutely elevated environmental exposures contribute to chronic health problems. However, only attention has been paid to the effects of modificate of exposure assessment methods in environmental health investigations, leading to uncertainty and gaps in our understanding of exposure- and dose-response relationships. The goal of the present study was to evaluate whether average or peak concentration exerts a greater influence on asthma outcome, and which of the exposure models may better explain various physiological responses generated by nitrogen dioxide (NO 2 ) or sulfur dioxide (SO 2 ) air pollutants. The effects of annual NO 2 and SO 2 exposures on asthma prevalence were determined in 137,040 17-year-old males in Israel, who underwent standard health examinations before induction to military service during 1999-2008. Three alternative models of cumulative exposure were used: arithmetic mean level (AM), average peak concentration (APC), and total number of air pollution exposure episodes (NEP). Air pollution data for NO 2 and SO 2 levels were linked to the residence of each subject and asthma prevalence was predicted using bivariate logistic regression. There was significant increased risk for asthma occurrence attributed to NO 2 exposure in all models with the highest correlations demonstrated using the APC model. Data suggested that exposure-response is better correlated with NO 2 peak concentration than with average exposure concentration in subjects with asthma. For SO 2 , there was a weaker but still significant exposure response association in all models. These differences may be related to differences in physiological responses including effects on different regions of the airways following exposure to these pollutants. NO 2 , which is poorly soluble in water, penetrates deep into the bronchial tree, producing asthmatic manifestations such as inflammation and increased mucus production as a result of high gaseous concentrations in the lung parenchyma. In contrast, SO 2 , which is highly water soluble, exerts its effects rapidly in the upper airways, leading to similar limited correlations at all levels of exposure with fewer asthmatic manifestations observed. These data indicate that differing exposure assessment methods may be needed to capture specific disease consequences associated with these air pollutants.

Modulation of thyroid hormone receptors by non-thyroidal stimuli

DOE Office of Scientific and Technical Information (OSTI.GOV)

ErkenBrack, D.E.; Clemons, G.K.

1988-01-01

The ability of non-thyroidal stimuli to affect the binding affinity and capacity of solubilized nuclear receptors for thyroid hormones was studied in a normal homeostatic system (erythropoiesis) and a pathobiologic one (lung-ozone interaction). No significant effects on affinity were found, as Kd control values for receptors derived from rat bone marrow averaged 57 (+/- 28) pM while experimental (hypoxic) values averaged 89 (+/- 55) pM. Kd control values in rat lung were found to average 142 (+/- 22) pM while average values derived from experimental protocols with ozone and methimazole were 267 (+/- 44) pM and 161 (+/- 35) pMmore » respectively. Finally, Kd control values for receptors derived from cultured MEL cells averaged 19 (+/- 2.6) pM while experimental values during exposure to DMSO or IGF1 were 23 (+/- 3.6) pM and 26 (+/- 11) pM respectively. In contrast, binding capacity (expressed as fmoles of hormone bound per unit protein of solubilized receptor) was markedly perturbed in several tissues by various agents: ozone effects on lung were shown by an average control value of 3.3 (+/- 0.4) as opposed to an experimental average of 28 (+/- 1.9); and hypoxia effects on erythroid tissue were displayed by an average control value of 0.7 (+/- 0.07) as opposed to the experimental figure of 1.8 (+/- 0.03). In cultured MEL cells, binding capacity was seen to be increased from control values of 388 (+/- 15) sites/cell to 1243 (+/- 142) sites/cell after DMSO exposure and 2002 (+/- 10) sites/cell after IGF1 exposure. Parallel experiments done with receptors derived from rat liver yielded values similar to those reported by other investigators and were unaffected by the experimental agents.« less

Assessment of seasonality in exposure to dioxins, furans and dioxin-like PCBs by using long-term food-consumption data.

PubMed

Feinberg, M; Soler, L; Contenot, S; Verger, P

2011-04-01

According to the European Food Safety Authority (EFSA) guidance related to uncertainties in dietary exposure assessment, exposure assessment based on short-term food-consumption surveys, such as 24-h recalls or 2-day records, tend to overestimate long-term exposure because of the assumption that the dietary pattern will be similar day after day over a lifetime. The aim of this study was to make an assessment of dietary exposure to polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), also called 'dioxins' and 'dioxin-like PCBs', using long-term household purchase and consumption survey data collected by TNS-Secodip. Weekly purchases of the major dioxins and dl-PCB vector products of these contaminants were collected for 328 single-person households, who participated at TNS-Secodip consumption surveys from 2003 to 2005 and who were single-person households in order to estimate better their consumption. These data were combined with average contamination levels of food products. Weekly gross average exposure was estimated at 10.2 pg toxic equivalent (WHO TEQ) kg(-1) bw week(-1) (95% confidence interval [9.6, 10.9]). According to the typical shape of the distribution of individual weekly exposures, it is sensible to fit an exponential law to these data. The mean was therefore 12.1 pg WHO TEQ kg(-1) bw week(-1). This value is higher than the arithmetic mean because it better takes into account inter-individual variability. It was estimated that about 20% of persons in this sample were exceeding the current health-based guidance value mainly due to high consumption of seafood and/or dairy products. Thanks to long survey duration (3 years) and the weekly recording of food consumption, it was possible to demonstrate the actual seasonality of dietary exposure to dioxins and dl-PCBs with a maximum between March and September; similar seasonality is observable for fish consumption. Autoregressive integrated moving average (ARIMA) models were adjusted to the time series and it was demonstrated that the number of times the upper limit of confidence intervals exceeds the provisional tolerable weekly intake (PTWI) is about 15 weeks per year on average. Finally, compared with the results obtained from data collected in the short-term surveys (1 week), this study does not suggest that short-term consumption surveys tend to overestimate the long-term exposure.

30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

Code of Federal Regulations, 2012 CFR

2012-07-01

... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

Code of Federal Regulations, 2011 CFR

2011-07-01

... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

Code of Federal Regulations, 2013 CFR

2013-07-01

... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

30 CFR 57.5060 - Limit on exposure to diesel particulate matter.

Code of Federal Regulations, 2010 CFR

2010-07-01

... diesel particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent... particulate matter (DPM) in an underground mine must not exceed an average eight-hour equivalent full shift... mine must not exceed an average eight-hour equivalent full shift airborne concentration of 350...

12 CFR 3.41 - Operational requirements for securitization exposures.

Code of Federal Regulations, 2014 CFR

2014-01-01

... loans 30, 60, and 90 days past due; default rates; prepayment rates; loans in foreclosure; property types; occupancy; average credit score or other measures of creditworthiness; average LTV ratio; and...

12 CFR 324.41 - Operational requirements for securitization exposures.

Code of Federal Regulations, 2014 CFR

2014-01-01

... loans 30, 60, and 90 days past due; default rates; prepayment rates; loans in foreclosure; property types; occupancy; average credit score or other measures of creditworthiness; average LTV ratio; and...

USE OF CONTINUOUS NEPHELOMETER TO MEASURE PERSONAL EXPOSURE TO PARTICULATE MATTER DURING THE 1998 U.S. EPA BALTIMORE PANEL STUDY

EPA Science Inventory

Personal exposures to particulate matter (PM) have typically been measured using filter samplers worn by the participants in exposure studies. Personal filter samplers, however, are limited to providing average mass concentrations integrated over a 12- to 24-hour period due to ...

Indoor External Radiation Risk in Densely Populated Regions of Southern Nigeria

NASA Astrophysics Data System (ADS)

Ife-Adediran, Oluwatobi O.; Uwadiae, Iyobosa B.

2018-02-01

It is known that certain types of building materials contain significant concentrations of natural radionuclides; consequently, exposure to indoor background radiation is from the combined radioactivity from the soil as well as building materials; indoor exposures therefore have higher radiation hazard potentials than outdoor exposures in this regard and hence, need to be monitored. In this paper, an evaluation of background ionizing radiation from different buildings in Lagos and Ibadan, Southwestern Nigeria was carried out to determine the exposure rate of the general public to indoor ionizing radiation. 630 in situ measurements from the different buildings were taken using a Geiger Muller counter (model GQ-320 Plus). The indoor dose rates (i.e., 50-120 nGy/h) were within the world average values while the Annual Effective Dose for most of the buildings were above the world average AED for indoor gamma exposure from building materials. The mean AED for Lagos and Ibadan due to indoor exposures were 0.37 and 0.39 mSv/y with Excess Lifetime Cancer Risk of 0.99E-3 and 1.05E-3, respectively.

Indoor External Radiation Risk in Densely Populated Regions of Southern Nigeria

NASA Astrophysics Data System (ADS)

Ife-Adediran, Oluwatobi O.; Uwadiae, Iyobosa B.

2018-05-01

It is known that certain types of building materials contain significant concentrations of natural radionuclides; consequently, exposure to indoor background radiation is from the combined radioactivity from the soil as well as building materials; indoor exposures therefore have higher radiation hazard potentials than outdoor exposures in this regard and hence, need to be monitored. In this paper, an evaluation of background ionizing radiation from different buildings in Lagos and Ibadan, Southwestern Nigeria was carried out to determine the exposure rate of the general public to indoor ionizing radiation. 630 in situ measurements from the different buildings were taken using a Geiger Muller counter (model GQ-320 Plus). The indoor dose rates (i.e., 50-120 nGy/h) were within the world average values while the Annual Effective Dose for most of the buildings were above the world average AED for indoor gamma exposure from building materials. The mean AED for Lagos and Ibadan due to indoor exposures were 0.37 and 0.39 mSv/y with Excess Lifetime Cancer Risk of 0.99E-3 and 1.05E-3, respectively.

Exposure of bakery and pastry apprentices to airborne flour dust using PM2.5 and PM10 personal samplers

PubMed Central

Mounier-Geyssant, Estelle; Barthélemy, Jean-François; Mouchot, Lory; Paris, Christophe; Zmirou-Navier, Denis

2007-01-01

Background This study describes exposure levels of bakery and pastry apprentices to flour dust, a known risk factor of occupational asthma. Methods Questionnaires on work activity were completed by 286 students. Among them, 34 performed a series of two personal exposure measurements using a PM2.5 and PM10 personal sampler during a complete work shift, one during a cold ("winter") period, and the other during a hot ("summer") period. Results Bakery apprentices experience greater average PM2.5 and PM10 exposures than pastry apprentices (p < 0.006). Exposure values for both particulate fractions are greater in winter (average PM10 values among bakers = 1.10 mg.m-3 [standard deviation: 0.83]) than in summer (0.63 mg.m-3 [0.36]). While complying with current European occupational limit values, these exposures exceed the ACGIH recommendations set to prevent sensitization to flour dust (0.5 mg.m-3). Over half the facilities had no ventilation system. Conclusion Young bakery apprentices incur substantial exposure to known airways allergens, a situation that might elicit early induction of airways inflammation. PMID:17976230

Indoor air quality at nine large-hub airports with and without designated smoking areas--United States, October-November 2012.

PubMed

2012-11-23

Secondhand smoke (SHS) exposure causes death and disease among nonsmoking adults and children. Adopting policies that completely prohibit smoking in all indoor areas is the only effective way to eliminate involuntary SHS exposure. Among the 29 large-hub U.S. airports, five currently allow smoking in specifically designated indoor areas accessible to the general public. In 2011, these five airports had a combined passenger boarding of approximately 110 million. To assess indoor air quality at the five large-hub U.S. airports with designated indoor smoking areas and compare it with the indoor air quality at four large-hub U.S. airports that prohibit smoking in all indoor areas, CDC measured the levels of respirable suspended particulates (RSPs), a marker for SHS. The results of this assessment determined that the average level of RSPs in the smoking-permitted areas of these five airports was 16 times the average level in nonsmoking areas (boarding gate seating sections) and 23 times the average level of RSPs in the smoke-free airports. The average RSP level in areas adjacent to the smoking-permitted areas was four times the average level in nonsmoking areas of the five airports with designated smoking areas and five times the average level in smoke-free airports. Smoke-free policies at the state, local, or airport authority levels can eliminate involuntary exposure to SHS inside airports and protect employees and travelers of all ages from SHS.

Exposure measurement error in PM2.5 health effects studies: A pooled analysis of eight personal exposure validation studies

PubMed Central

2014-01-01

Background Exposure measurement error is a concern in long-term PM2.5 health studies using ambient concentrations as exposures. We assessed error magnitude by estimating calibration coefficients as the association between personal PM2.5 exposures from validation studies and typically available surrogate exposures. Methods Daily personal and ambient PM2.5, and when available sulfate, measurements were compiled from nine cities, over 2 to 12 days. True exposure was defined as personal exposure to PM2.5 of ambient origin. Since PM2.5 of ambient origin could only be determined for five cities, personal exposure to total PM2.5 was also considered. Surrogate exposures were estimated as ambient PM2.5 at the nearest monitor or predicted outside subjects’ homes. We estimated calibration coefficients by regressing true on surrogate exposures in random effects models. Results When monthly-averaged personal PM2.5 of ambient origin was used as the true exposure, calibration coefficients equaled 0.31 (95% CI:0.14, 0.47) for nearest monitor and 0.54 (95% CI:0.42, 0.65) for outdoor home predictions. Between-city heterogeneity was not found for outdoor home PM2.5 for either true exposure. Heterogeneity was significant for nearest monitor PM2.5, for both true exposures, but not after adjusting for city-average motor vehicle number for total personal PM2.5. Conclusions Calibration coefficients were <1, consistent with previously reported chronic health risks using nearest monitor exposures being under-estimated when ambient concentrations are the exposure of interest. Calibration coefficients were closer to 1 for outdoor home predictions, likely reflecting less spatial error. Further research is needed to determine how our findings can be incorporated in future health studies. PMID:24410940

Results of simultaneous radon and thoron measurements in 33 metropolitan areas of Canada

PubMed Central

Chen, Jing; Bergman, Lauren; Falcomer, Renato; Whyte, Jeff

2015-01-01

Radon has been identified as the second leading cause of lung cancer after tobacco smoking. 222Rn (radon gas) and 220Rn (thoron gas) are the most common isotopes of radon. In order to assess thoron contribution to indoor radon and thoron exposure, a survey of residential radon and thoron concentrations was initiated in 2012 with ∼4000 homes in the 33 census metropolitan areas of Canada. The survey confirmed that indoor radon and thoron concentrations are not correlated and that thoron concentrations cannot be predicted from widely available radon information. The results showed that thoron contribution to the radiation dose varied from 0.5 to 6 % geographically. The study indicated that, on average, thoron contributes ∼3 % of the radiation dose due to indoor radon and thoron exposure in Canada. Even though the estimated average thoron concentration of 9 Bq m−3 (population weighted) in Canada is low, the average radon concentration of 96 Bq m−3 (population weighted) is more than double the worldwide average indoor radon concentration. It is clear that continued efforts are needed to further reduce the exposure and effectively reduce the number of lung cancers caused by radon. PMID:24748485

Prenatal Influences on Human Sexual Orientation: Expectations versus Data.

PubMed

Breedlove, S Marc

2017-08-01

In non-human vertebrate species, sexual differentiation of the brain is primarily driven by androgens such as testosterone organizing the brains of males in a masculine fashion early in life, while the lower levels of androgen in developing females organize their brains in a feminine fashion. These principles may be relevant to the development of sexual orientation in humans, because retrospective markers of prenatal androgen exposure, namely digit ratios and otoacoustic emissions, indicate that lesbians, on average, were exposed to greater prenatal androgen than were straight women. Thus, the even greater levels of prenatal androgen exposure experienced by fetal males may explain why the vast majority of them grow up to be attracted to women. However, the same markers indicate no significant differences between gay and straight men in terms of average prenatal androgen exposure, so the variance in orientation in men cannot be accounted for by variance in prenatal androgen exposure, but may be due to variance in response to prenatal androgens. These data contradict several popular notions about human sexual orientation. Sexual orientation in women is said to be fluid, sometimes implying that only social influences in adulthood are at work, yet the data indicate prenatal influences matter as well. Gay men are widely perceived as under-masculinized, yet the data indicate they are exposed to as much prenatal androgen as straight men. There is growing sentiment to reject "binary" conceptions of human sexual orientations, to emphasize instead a spectrum of orientations. Yet the data indicate that human sexual orientation is sufficiently polarized that groups of lesbians, on average, show evidence of greater prenatal androgen exposure than groups of straight women, while groups of gay men have, on average, a greater proportion of brothers among their older siblings than do straight men.