Sample records for radiodiagnostic exposure time

  1. Noise suppression by time exposure oscilloscope photography.

    NASA Technical Reports Server (NTRS)

    Huchital, G. S.; Young, M.

    1972-01-01

    We describe a simple and inexpensive means of enhancing repetitive signals obscured by noise with roughly equal amplitude. The signal and noise are displayed on an oscilloscope, and we perform a time average over many traces by time exposure photography. If the oscilloscope triggering is synchronous with the signal, the result is a significant suppression of the offending noise.

  2. Predicting survival time for cold exposure

    NASA Astrophysics Data System (ADS)

    Tikuisis, Peter

    1995-06-01

    The prediction of survival time (ST) for cold exposure is speculative as reliable controlled data of deep hypothermia are unavailable. At best, guidance can be obtained from case histories of accidental exposure. This study describes the development of a mathematical model for the prediction of ST under sedentary conditions in the cold. The model is based on steady-state heat conduction in a single cylinder comprised of a core and two concentric annular shells representing the fat plus skin and the clothing plus still boundary layer, respectively. The ambient condition can be either air or water; the distinction is made by assigning different values of insulation to the still boundary layer. Metabolic heat production ( M) is comprised of resting and shivering components with the latter predicted by temperature signals from the core and skin. Where the cold exposure is too severe for M to balance heat loss, ST is largely determined by the rate of heat loss from the body. Where a balance occurs, ST is governed by the endurance time for shivering. End of survival is marked by the deep core temperature reaching a value of 30° C. The model was calibrated against survival data of cold water (0 to 20° C) immersion and then applied to cold air exposure. A sampling of ST predictions for the nude exposure of an average healthy male in relatively calm air (1 km/h wind speed) are the following: 1.8, 2.5, 4.1, 9.0, and >24 h for -30, -20, -10, 0, and 10° C, respectively. With two layers of loose clothing (average thickness of 1 mm each) in a 5 km/h wind, STs are 4.0, 5.6, 8.6, 15.4, and >24 h for -50, -40, -30, -20, and -10° C. The predicted STs must be weighted against the extrapolative nature of the model. At present, it would be prudent to use the predictions in a relative sense, that is, to compare or rank-order predicted STs for various combinations of ambient conditions and clothing protection.

  3. The WFIRST Galaxy Survey Exposure Time Calculator

    NASA Technical Reports Server (NTRS)

    Hirata, Christopher M.; Gehrels, Neil; Kneib, Jean-Paul; Kruk, Jeffrey; Rhodes, Jason; Wang, Yun; Zoubian, Julien

    2013-01-01

    This document describes the exposure time calculator for the Wide-Field Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works in both imaging and spectroscopic modes. In addition to the standard ETC functions (e.g. background and SN determination), the calculator integrates over the galaxy population and forecasts the density and redshift distribution of galaxy shapes usable for weak lensing (in imaging mode) and the detected emission lines (in spectroscopic mode). The source code is made available for public use.

  4. The WFIRST Galaxy Survey Exposure Time Calculator

    E-print Network

    Hirata, Christopher M; Kneib, Jean-Paul; Kruk, Jeffrey; Rhodes, Jason; Wang, Yun; Zoubian, Julien

    2012-01-01

    This document describes the exposure time calculator for the Wide-Field Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works in both imaging and spectroscopic modes. In addition to the standard ETC functions (e.g. background and S/N determination), the calculator integrates over the galaxy population and forecasts the density and redshift distribution of galaxy shapes usable for weak lensing (in imaging mode) and the detected emission lines (in spectroscopic mode). The source code is made available for public use.

  5. Effects of Graduated Exposure with Feedback of Exposure Times on Snake Phobias

    ERIC Educational Resources Information Center

    Becker, Horst G.; Costello, C. G.

    1975-01-01

    The subject-controlled graduated exposure of a snake with feedback of exposure times resulted in significantly less avoidance behaviors for snake-phobic subjects than for control snake-phobic subjects who did not receive therapy. (Author)

  6. Exposure Time Optimization for Highly Dynamic Star Trackers

    PubMed Central

    Wei, Xinguo; Tan, Wei; Li, Jian; Zhang, Guangjun

    2014-01-01

    Under highly dynamic conditions, the star-spots on the image sensor of a star tracker move across many pixels during the exposure time, which will reduce star detection sensitivity and increase star location errors. However, this kind of effect can be compensated well by setting an appropriate exposure time. This paper focuses on how exposure time affects the star tracker under highly dynamic conditions and how to determine the most appropriate exposure time for this case. Firstly, the effect of exposure time on star detection sensitivity is analyzed by establishing the dynamic star-spot imaging model. Then the star location error is deduced based on the error analysis of the sub-pixel centroiding algorithm. Combining these analyses, the effect of exposure time on attitude accuracy is finally determined. Some simulations are carried out to validate these effects, and the results show that there are different optimal exposure times for different angular velocities of a star tracker with a given configuration. In addition, the results of night sky experiments using a real star tracker agree with the simulation results. The summarized regularities in this paper should prove helpful in the system design and dynamic performance evaluation of the highly dynamic star trackers. PMID:24618776

  7. Characterizing Determinants of Risk: Concentration, Duration, and Timing of Exposure

    EPA Science Inventory

    An ongoing challenge in human health risk assessment is to determine the best approach for characterizing the risk from real-world exposures. Three major determinants characterize exposure: concentration (how much), duration (the frequency and how long), and critical timing (whe...

  8. Calibration Lamp Exposure Time Estimates Date: April 30, 2002

    E-print Network

    Colorado at Boulder, University of

    , COS Instrument Scientist Date Reviewed By: Jon A. Morse 3/13/01 Dr. Jon Morse, COS Project Scientist Astronomy Reviewed: Approved: Calibration Lamp Exposure Time Estimates Size Code Indent No. Document No. Rev

  9. Effects of time-variant exposure on toxic substance response.

    PubMed Central

    Morrison, P F

    1987-01-01

    Sources of time-variant exposure to toxic substances are identified and examined for their effects on the estimation of response. It is shown that only time-averaged target tissue concentrations are required to obtain rigorous risk estimates from the one-hit and multihit models. In contrast, detailed concentration histories need to be retained throughout analyses involving two-event models with intermediate-stage clonal growth advantage (clonal two-stage) and multistage models. Cumulative incidence ratios, based on the exact to time-averaged treatment of concentration time dependencies, are evaluated for substances whose toxic responses exhibit moderate (arsenic) and strong (ethylene dibromide) dependence on time of actual exposure. These ratios reveal that time-averaged dose approximations may lead to several orders of magnitude error in both the multistage and clonal two-stage models if exposure periods are short, and that 3.4-fold (arsenic) and 8-fold (ethylene dibromide) errors still exist even when an actual two-thirds lifetime exposure is averaged over a full lifetime. Finally, the effects of time-variant exposure on risk estimation due to migration and birth-death in an epidemiological setting are examined. A residence time distribution calculation shows that, if these effects are ignored for a population orally exposed to arsenic and characterized by an out-migration rate in excess of 5%/yr, response errors will exceed an order of magnitude. PMID:3329094

  10. Novel Monitor Paradigm for Real-Time Exposure Assessment

    PubMed Central

    Negi, Indira; Tsow, Francis; Tanwar, Kshitiz; Zhang, Lihua; Iglesias, Rodrigo A.; Chen, Cheng; Rai, Anant; Forzani, Erica S.; Tao, Nongjian (NJ)

    2013-01-01

    A wearable monitor that can reliably, accurately and continuously measure personal exposure levels of various toxicants would not only accelerate the current environmental and occupational health and safety studies, but also enable new studies that are not possible with the current monitoring technology. Developing such a monitor has been a difficult challenge, and requires innovative sensing science and creative engineering. We have developed, built and tested a wearable monitor for real-time detection of toxic hydrocarbons and acids in environment. The monitor is low-cost, accurate, and user-friendly. In addition, it can communicate wirelessly with a cell phone in which the monitoring results can be processed, displayed, stored and transmitted to a designated computer. We have validated the functions and performance of the monitor, and carried out field tests with workers involving waste management, fire overhaul, and floor-cleaning activities, as well as with first- and second-hand smokers. The averaged exposure levels are in agreement with those determined by the standard NIOSH methods. The monitor provides accurate and real-time exposure assessment for the workers involving different activities. The real-time and continuous monitoring capability makes it possible to correlate the exposure levels with different activities and changes in the microenvironments. The monitor provides unprecedented real-time information that will help advance occupational safety and environmental health studies. It may also be used to better protect workers from occupational overexposure to toxic molecules. PMID:20551996

  11. Radiation Exposure From Medical Imaging Time to Regulate?

    E-print Network

    Brenner, David Jonathan

    modern medical imaging, there are serious is- sues of quality control, training, and, particularly authority to regulate usage of x-ray devices. The exception is the 1992 Mammography Quality Stan- dards ActCOMMENTARY Radiation Exposure From Medical Imaging Time to Regulate? David J. Brenner, PhD Hedvig

  12. Use of time to pregnancy to study environmental exposures

    SciTech Connect

    Baird, D.D.; Wilcox, A.J.; Weinberg, C.R.

    1986-09-01

    There is need in reproductive epidemiology for sensitive and convenient screening tools that can be used to study environmental and occupational exposures. The measurement of fecundability (the probability of pregnancy in each cycle) by ascertaining how long it takes couples to conceive, may be useful for this purpose. Theoretically, exposures that interfere with any of the biologic processes involved in achieving pregnancy could lower fecundability among exposed men or women. To evaluate problems with collecting data on time to pregnancy, telephone interviews were conducted with nearly 700 pregnant women who reported having planned their pregnancies. Power curves were developed based on the distribution of time to pregnancy in the interviewed population. These curves indicate that relatively small sample sizes are sufficient for investigating an exposure. For example, the authors estimate that to detect a given 50% drop in mean fecundability with 80% power would require data from 55 exposed and 55 unexposed women who are pregnant. Disadvantages of using time to pregnancy as a reproductive endpoint include susceptibility to selection bias and need for data on several potential confounding variables. The next step in evaluating time to pregnancy as a reproductive endpoint is to apply it in studies of environmental or occupational exposures.

  13. Developmental timing of perchlorate exposure alters threespine stickleback dermal bone.

    PubMed

    Furin, Christoff G; von Hippel, Frank A; Postlethwait, John; Buck, C Loren; Cresko, William A; O'Hara, Todd M

    2015-08-01

    Adequate levels of thyroid hormone are critical during development and metamorphosis, and for maintaining metabolic homeostasis. Perchlorate, a common contaminant of water sources, inhibits thyroid function in vertebrates. We utilized threespine stickleback (Gasterosteus aculeatus) to determine if timing of perchlorate exposure during development impacts adult dermal skeletal phenotypes. Fish were exposed to water contaminated with perchlorate (30mg/L or 100mg/L) beginning at 0, 3, 7, 14, 21, 42, 154 or 305days post fertilization until sexual maturity at 1year of age. A reciprocal treatment moved stickleback from contaminated to clean water on the same schedule providing for different stages of initial exposure and different treatment durations. Perchlorate exposure caused concentration-dependent significant differences in growth for some bony traits. Continuous exposure initiated within the first 21days post fertilization had the greatest effects on skeletal traits. Exposure to perchlorate at this early stage can result in small traits or abnormal skeletal morphology of adult fish which could affect predator avoidance and survival. PMID:25753171

  14. Time variant exposure analysis (TVEA): a measurement tool for characterizing particulate exposure determinants in construction.

    PubMed

    Kalil, Andrew J; Woskie, Susan R; Holcroft, Christina; Ellenbecker, Michael; Buchholz, Bryan

    2004-12-01

    A work sampling-based approach, time variant exposure analysis (TVEA), was developed for assessment of determinants for particulate air contaminants in dynamic construction environments. To use TVEA, the field researcher records observations at fixed intervals to systematically survey over 30 potential determinants that could affect exposure to three types of particulate matter: quartz-containing dusts, diesel exhaust, and a general grouping of "other particles" that includes welding fume and wood dust. Two field studies were conducted to address questions of inter-rater reliability (n = 20) and coding interval appropriateness (n = 21) for the TVEA method. At least substantial inter-rater agreement (kappa > 0.60) was obtained for the TVEA variables related to tool or machine use, process, material, source intensity, and source orientation. Kappa values for source direction (0.22-0.38) and number of sources (0.38-0.60) showed comparatively lower agreement for all particulate types. Observation interval appropriateness was analyzed using linear regression to compare a 5-min observation interval "gold standard" with alternate intervals. Regression statistics indicated that while 30 min is an acceptable interval for exposure assessment, 15 min optimizes precision and practicality by ensuring that 95% of all observations differ less than ten percentage points from the "true" values. TVEA is a useful exposure assessment tool for the dynamic construction environment. It is flexible in that only those determinants that are of interest need be coded and the coding interval can be adjusted to accommodate the level of precision desired. PMID:15742711

  15. Exposure time calculator for Immersion Grating Infrared Spectrograph: IGRINS

    NASA Astrophysics Data System (ADS)

    Le, Huynh Anh N.; Pak, Soojong; Jaffe, Daniel T.; Kaplan, Kyle; Lee, Jae-Joon; Im, Myungshin; Seifahrt, Andreas

    2015-06-01

    We present an exposure-time calculator (ETC) for the Immersion Grating Infrared Spectrograph (IGRINS). The signal and noise values are calculated by taking into account the telluric background emission and absorption, the emission and transmission of the telescope and instrument optics, and the dark current and read noise of the infrared detector arrays. For the atmospheric transmission, we apply models based on the amount of precipitable water vapor along the line of sight to the target. The ETC produces the expected signal-to-noise ratio (S/N) for each resolution element, given the exposure-time and number of exposures. In this paper, we compare the simulated continuum S/N for the early-type star HD 124683 and the late-type star GSS 32, and the simulated emission line S/N for the H2 rovibrational transitions from the Iris Nebula NGC 7023 with the observed IGRINS spectra. The simulated S/N from the ETC is overestimated by 40-50% for the sample continuum targets.

  16. Importance of population structure at the time of toxicant exposure.

    PubMed

    Stark, J D; Banken, J A

    1999-03-01

    Populations in nature often consist of a mixture of stages and ages, yet toxicological studies even demographic studies, usually evaluate one starting life stage. In this study it was asked whether the starting age/stage structure of a population at the time of initial pesticide exposure influenced the impact that pesticides have on population growth rates. This question was answered by exposing differently structured populations of two terrestrial arthropod species, the two-spotted spider mite, Tetranychus urticae (Koch), and the pea aphid, Acrythosiphon pisum (Harris), to pesticides. The three structured populations tested were (1) eggs or neonates for A. pisum and T. urticae, respectively, (2) stable age distribution, and (3) young adult females only. Instantaneous rates of population increase (ri) for the three structured populations were determined over time without exposure to pesticides (control) and after exposure to pesticides. Populations of T. urticae were exposed to 100 ppm of the pesticide dicofol; populations of A. pisum were exposed to 200 ppm Neemix. The ri for the three control populations of T. urticae and A. pisum converged in a closed system 16 and 17 days after the start of the study, respectively. Unlike the control populations, the ri of the three treated populations did not converge by Day 16 for the mite species or Day 17 for the aphid species after exposure to pesticides. Growth rates of populations started as eggs (mites) or neonates (aphids) remained significantly lower than those of the adult or mixed-age populations (Pexposure to 100 ppm dicofol was equivalent to the LC21 for the egg stage, the LC59 for immatures, and the LC69 for adult T. urticae. Thus, even though the egg stage was the least susceptible stage of T. urticae, populations started as eggs were significantly more susceptible than populations started as the stable age distribution or as adults. It was concluded that the initial structure of a population does have an influence on the impact that pesticides will have on populations and that age/stage structure should be given serious consideration when evaluating toxicant effects. PMID:10090817

  17. Time-Dependent Propensity Score for Assessing the Effect of Vaccine Exposure on Pregnancy Outcomes through Pregnancy Exposure Cohort Studies

    PubMed Central

    Xu, Ronghui; Luo, Yunjun; Glynn, Robert; Johnson, Diana; Jones, Kenneth L.; Chambers, Christina

    2014-01-01

    Women are advised to be vaccinated for influenza during pregnancy and may receive vaccine at any time during their pregnancy. In observational studies evaluating vaccine safety in pregnancy, to account for such time-varying vaccine exposure, a time-dependent predictor can be used in a proportional hazards model setting for outcomes such as spontaneous abortion or preterm delivery. Also, due to the observational nature of pregnancy exposure cohort studies and relatively low event rates, propensity score (PS) methods are often used to adjust for potential confounders. Using Monte Carlo simulation experiments, we compare two different ways to model the PS for vaccine exposure: (1) logistic regression treating the exposure status as binary yes or no; (2) Cox regression treating time to exposure as time-to-event. Coverage probability of the nominal 95% confidence interval for the exposure effect is used as the main measure of performance. The performance of the logistic regression PS depends largely on how the exposure data is generated. In contrast, the Cox regression PS consistently performs well across the different data generating mechanisms that we have considered. In addition, the Cox regression PS allows adjusting for potential time-varying confounders such as season of the year or exposure to additional vaccines. The application of the Cox regression PS is illustrated using data from a recent study of the safety of pandemic H1N1 influenza vaccine during pregnancy. PMID:24625623

  18. Assessing the Impact of Exposure Time and Incapacitation on Longitudinal Trajectories of Criminal Offending.

    ERIC Educational Resources Information Center

    Piquero, Alex; Blumstein, Alfred; Brame, Robert; Haapanen, Rudy; Mulvey, Edward P.; Nagin, Daniel S.

    2001-01-01

    Examined effect of accounting for exposure (incarceration) time on arrest rate of 272 paroled serious offenders followed through age 33. Analysis without exposure time adjustments suggested that over 92 percent exhibited highest arrest activity in late teens and early 20s. Adjusted for exposure time, about 72 percent showed a decline in arrest…

  19. ETC-42 : A Generic, VO Compliant, Exposure Time Calculator

    NASA Astrophysics Data System (ADS)

    Apostolakos, N.; Surace, C.; Chabaud, P.-Y.; LeLeu, G.; LAM scientists

    2012-09-01

    We developed at CeSAM (Centre de donneeS Astrophysiques de Marseille) a new, Virtual Observatory compliant, Exposure Time Calculator, ETC-42. This new ETC performs an instrument-independent computation, derived from the comparison of several (instrument focused) existing ETCs, enabling it to cover a wide range of existing or future instrumentation. Its flexible design and support for plugins allows for easy addition of new computation methods, ensuring its usefulness even for future technologies or for instrumentation with specific calculation requirements. This paper describes the current calculation functionality, the interfaces used for communication with the user and it concludes with the design and frameworks used for achieving the systems flexibility and extensibility.

  20. Estimates of exposure rates and fallout arrival times near the Nevada Test Site

    Microsoft Academic Search

    Carol B. Thompson

    1990-01-01

    One of the tasks of the Off-Site Radiation Exposure Review Project (ORERP) was to estimate doses to individuals resulting from exposure to fallout from nuclear testing at the Nevada Test Site (NTS). Dose estimates are based on estimates of the exposure rate 12 h post-detonation (H + 12) and the time of fallout arrival from events producing discernible fallout at

  1. Night time aircraft noise exposure and children's cognitive performance.

    PubMed

    Stansfeld, Stephen; Hygge, Staffan; Clark, Charlotte; Alfred, Tamuno

    2010-01-01

    Chronic aircraft noise exposure in children is associated with impairment of reading and long-term memory. Most studies have not differentiated between day or nighttime noise exposure. It has been hypothesized that sleep disturbance might mediate the association of aircraft noise exposure and cognitive impairment in children. This study involves secondary analysis of data from the Munich Study and the UK Road Traffic and Aircraft Noise Exposure and Children's Cognition and Health (RANCH) Study sample to test this. In the Munich study, 330 children were assessed on cognitive measures in three measurement waves a year apart, before and after the switchover of airports. Self-reports of sleep quality were analyzed across airports, aircraft noise exposure and measurement wave to test whether changes in nighttime noise exposure had any effect on reported sleep quality, and whether this showed the same pattern as for changes in cognitive performance. For the UK sample of the RANCH study, night noise contour information was linked to the children's home and related to sleep disturbance and cognitive performance. In the Munich study, analysis of sleep quality questions showed no consistent interactions between airport, noise, and measurement wave, suggesting that poor sleep quality does not mediate the association between noise exposure and cognition. Daytime and nighttime aircraft noise exposure was highly correlated in the RANCH study. Although night noise exposure was significantly associated with impaired reading and recognition memory, once home night noise exposure was centered on daytime school noise exposure, night noise had no additional effect to daytime noise exposure. These analyses took advantage of secondary data available from two studies of aircraft noise and cognition. They were not initially designed to examine sleep disturbance and cognition, and thus, there are methodological limitations which make it less than ideal in giving definitive answers to these questions. In conclusion, results from both studies suggest that night aircraft noise exposure does not appear to add any cognitive performance decrement to the cognitive decrement induced by daytime aircraft noise alone. We suggest that the school should be the main focus of attention for protection of children against the effects of aircraft noise on school performance. PMID:20871180

  2. A new real time filter for local exposure correction in panoramic radiographs

    SciTech Connect

    Frosio, I.; Borghese, N. A. [Laboratory of Applied Intelligent Systems-AIS Lab, Department of Computer Science, Via Comelico 39/41-20135 Milan (Italy); University of Milano (Italy)

    2006-09-15

    A new real time filter for local exposure correction in panoramic radiographs is presented here. The filter, called PaRSEC, allows eliminating the exposure artifacts, mainly introduced by Automatic Exposure Control (AEC) systems. These artifacts reduce the image readability and its diagnostic utility. The PaRSEC filter operates a local exposure equalization, based on a reliable estimate of the column mean gray level. Qualitative and quantitative results are reported for typical panoramic radiographs. They show a complete removal of the artifacts. The method compares favorably with other classical methods targeted to exposure correction.

  3. Determination of optimal exposure time for imaging of blood flow changes with laser speckle contrast imaging

    Microsoft Academic Search

    Shuai Yuan; Anna Devor

    2005-01-01

    Laser speckle contrast imaging is becoming an established method for full-field imaging of cerebral blood flow dynamics in animal models. The sensitivity and noise in the measurement of blood flow changes depend on the camera exposure time. The relation among sensitivity, noise, and camera exposure time was investigated experimentally by imaging the speckle contrast changes in the brain after electrical

  4. The Timing of Exposure in Clinic-Based Treatment for Childhood Anxiety Disorders

    ERIC Educational Resources Information Center

    Gryczkowski, Michelle R.; Tiede, Michael S.; Dammann, Julie E.; Jacobsen, Amy Brown; Hale, Lisa R.; Whiteside, Stephen P. H.

    2013-01-01

    The present study examines treatment length and timing of exposure from two child anxiety disorders clinics. Data regarding symptoms and treatment characteristics for 28 youth were prospectively obtained through self, parent, and therapist report at each session. Information regarding length of treatment, timing of exposure initiation, and…

  5. Retention of Idioms Following One-Time Exposure

    ERIC Educational Resources Information Center

    Reuterskiold, Christina; Van Lancker Sidtis, Diana

    2013-01-01

    This study explored retention of idioms and novel (i.e. newly created or grammatically generated) expressions in English-speaking girls following exposure only once during a conversation. Our hypothesis was that idioms, because of their inherent holistic, nonliteral and social characteristics, are acquired differently and more rapidly than novel…

  6. Farmworker children's residential non-dietary exposure estimates from micro-level activity time series.

    PubMed

    Beamer, Paloma I; Canales, Robert A; Bradman, Asa; Leckie, James O

    2009-11-01

    Farmworkers' children may have increased pesticide exposure through dermal absorption and non-dietary ingestion, routes that are difficult to measure and model. The Cumulative Aggregate Simulation of Exposure (CASE) model, integrates the complexity of human behavior and variability of exposure processes by combining micro-level activity time series (MLATS) and mechanistic exposure equations. CASE was used to estimate residential non-dietary organophosphate pesticide exposure (i.e., inhalation, dermal, and non-dietary ingestion) to California farmworker children and evaluate the micro-activity approach. MLATS collected from children and distributions developed from pesticide measurements in farmworkers' residences served as inputs. While estimated diazinon exposure was greater for inhalation, chlorpyrifos exposure was greater for the other routes. Greater variability existed between children (sigma(B)(2)=0.22-0.39) than within each child's simulations (sigma(W)(2)=0.01-0.02) for dermal and non-dietary ingestion. Dermal exposure simulations were not significantly different than measured values from dosimeters worn by the children. Non-dietary ingestion exposure estimates were comparable to duplicate diet measurements, indicating this route may contribute substantially to aggregate exposure. The results suggest the importance of the micro-activity approach for estimating non-dietary exposure. Other methods may underestimate exposure via these routes. Model simulations can be used to identify at-risk children and target intervention strategies. PMID:19744713

  7. Population exposure to ultraviolet radiation in Finland 1920-1995: Exposure trends and a time-series analysis of exposure and cutaneous melanoma incidence

    SciTech Connect

    Kojo, Katja [STUK-Radiation and Nuclear Safety Authority, 00881 Helsinki (Finland) and School of Public Health, University of Tampere, 33014 Tampere (Finland)]. E-mail: katja.kojo@uta.fi; Jansen, Christer T. [Department of Dermatology, University of Turku, 20540 Turku (Finland); Nybom, Pia [University of Art and Design, 00560 Helsinki (Finland); Huurto, Laura [STUK-Radiation and Nuclear Safety Authority, 00881 Helsinki (Finland); Laihia, Jarmo [Department of Dermatology, University of Turku, 20540 Turku (Finland); Ilus, Taina [STUK-Radiation and Nuclear Safety Authority, 00881 Helsinki (Finland); Auvinen, Anssi [STUK-Radiation and Nuclear Safety Authority, 00881 Helsinki (Finland); School of Public Health, University of Tampere, 33014 Tampere (Finland)

    2006-05-15

    Ultraviolet radiation (UVR) is the principal cause of cutaneous malignant melanoma (CMM). However, the relation between CMM and UVR exposure is not clear. We present the trends of population exposure to UVR and conduct a time-series analysis of the relation between UVR exposure and incidence of CMM. Data on CMM incidence were obtained from the Finnish Cancer Registry. Clothing coverage of the body was scored from archival photographs and the proportion of uncovered skin was used as a measure of solar exposure. Information on the number of sunny resort holidays, duration of annual holidays, and sunscreen sales were obtained from various sources. Exposed skin area doubled from 1920 to 1985. The average duration of annual holidays increased 30-fold. The number of sunny resort holidays and the sales of sunscreens increased rapidly from 1980. CMM was most strongly associated with solar exposure of 5-19 years earlier. There is a considerable decrease in clothing coverage during the 20th century. UVR exposure preceding CMM occurrence 4 years or less does not appear relevant, whereas the period 5-19 years prior to CMM occurrence might be the most relevant period. However, findings of ecological studies may not be applicable at the individual level.

  8. The design of a miniature personal exposure monitor for continuous real-time data acquisition in electromagnetic field exposure assessment

    SciTech Connect

    Hansen, N.H.; Conroy, T.J.; Wilson, B.W.

    1994-06-01

    The design of a small, light-weight personal exposure monitor suitable for use in EMF exposure assessment studies is nearing completion at Pacific Northwest Laboratory. The monitor is designed to be non-obtrusive, battery operated, and able to continuously record extremely low-frequency (ELF) (1Ohz--500hz) magnetic-field data. It also captures high-frequency (500hz--1OMhz) transients that exceed a preset threshold, retaining the largest transients in memory. The monitor can record one or more days of data on a single easily replaceable, credit-card-size memory (PCMCIA). A battery charge will last a minimum of one day. Batteries are rechargeable and easily replaced. A data-compression algorithm is under development that will be tailored to the efficient compression of low-frequency EMF signals and will permit data to be logged for at least one day before swapping memory cards. The memory cards are readable by a base- station computer that can perform analysis of the data. The monitor is designed to accommodate four inputs supporting full-field sensors as well as a proposed ocular exposure measurement system. Our design effort has shown that a practical personal exposure monitor for EMF can be built based on current technology, continuous logging of real-time ELF waveforms is both feasible and practical, and such a device is appropriate for proposed EMF exposure studies.

  9. Duration and Timing of Exposure to Neighborhood Poverty and the Risk of Adolescent Parenthood

    PubMed Central

    Wodtke, Geoffrey T.

    2013-01-01

    Theory suggests that the impact of neighborhood poverty depends on both the duration and timing of exposure. Previous research, however, does not properly analyze the sequence of neighborhoods to which children are exposed throughout the early life course. This study investigates the effects of different longitudinal patterns of exposure to disadvantaged neighborhoods on the risk of adolescent parenthood. It follows a cohort of children in the PSID from age 4 to 19 and uses novel methods for time-varying exposures that overcome critical limitations of conventional regression when selection processes are dynamic. Results indicate that sustained exposure to poor neighborhoods substantially increases the risk of becoming a teen parent and that exposure to neighborhood poverty during adolescence may be more consequential than exposure earlier during childhood. PMID:23720166

  10. EFFECTS OF THE DURATION AND TIMING OF DIETARY METHYL PARATHION EXPOSURE ON BOBWHITE REPRODUCTION

    EPA Science Inventory

    Two northern bobwhite (colinus virginianus) reproduction tests were conducted concurrently to evaluate how the duration and time of initiation of methyl parathion exposure affeCted dose-response relationships of reproductive parameters. n the long-term exposure test, pairs of adu...

  11. Sea lice and salmon population dynamics: effects of exposure time for migratory fish

    E-print Network

    Lewis, Mark

    Sea lice and salmon population dynamics: effects of exposure time for migratory fish Martin Krkosek of Alberta, Edmonton, Alberta T6G 2R3, Canada 3 Salmon Coast Field Station, Simoom Sound, British Columbia V0 by the migration of wild fishes, which determines the period of exposure to parasites. For Pacific salmon

  12. Determining times to maximum urine excretion of 1-aminopyrene after diesel exhaust exposure

    Microsoft Academic Search

    Susan Huyck; Pamela Ohman-Strickland; Lin Zhang; Jian Tong; X U Xu

    2010-01-01

    Biomonitoring of exposures to toxins is an important tool for monitoring public health and safety. Using this tool, exposures are typically measured by the collection of biological specimens such as blood and urine samples. Urine sampling represents a more convenient and less-invasive alternative to blood sampling; however, less work has been published on methodologies for characterizing the time course of

  13. REAL-TIME MODELING OF MOTOR VEHICLE EMISSIONS FOR ESTIMATING HUMAN EXPOSURES NEAR ROADWAYS

    EPA Science Inventory

    The United States Environmental Protection Agency's (EPA) National Exposure Research Laboratory is developing a real-time model of motor vehicle emissions to improve the methodology for modeling human exposure to motor vehicle emissions. The overall project goal is to develop ...

  14. A network-based approach for estimating pedestrian journey-time exposure to air pollution.

    PubMed

    Davies, Gemma; Whyatt, J Duncan

    2014-07-01

    Individual exposure to air pollution depends not only upon pollution concentrations in the surrounding environment, but also on the volume of air inhaled, which is determined by an individual's physiology and activity level. This study focuses on journey-time exposure, using network analysis in a GIS environment to identify pedestrian routes between multiple origins and destinations throughout the city of Lancaster, North West England. For each segment of a detailed footpath network, exposure was calculated accounting for PM2.5 concentrations (estimated using an atmospheric dispersion model) and respiratory minute volume (varying between individuals and with slope). For each of the routes generated the cumulative exposure to PM2.5 was estimated, allowing for easy comparison between multiple routes. Significant variations in exposure were found between routes depending on their geography, as well as in response to variations in background concentrations and meteorology between days. Differences in physiological characteristics such as age or weight were also seen to impact journey-time exposure considerably. In addition to assessing exposure for a given route, the approach was used to identify alternative routes that minimised journey-time exposure. Exposure reduction potential varied considerably between days, with even subtle shifts in route location, such as to the opposite side of the road, showing significant benefits. The method presented is both flexible and scalable, allowing for the interactions between physiology, activity level, pollution concentration and journey duration to be explored. In enabling physiology and activity level to be integrated into exposure calculations a more comprehensive estimate of journey-time exposure can be made, which has potential to provide more realistic inputs for epidemiological studies. PMID:24704957

  15. Unsteady near wall residence times and shear exposure in model distal arterial bypass grafts.

    PubMed

    Sherwin, S J; Doorly, D J; Franke, P; Peiró, J

    2002-01-01

    Building on previous studies of unsteady flow within model distal bypass grafts we analyse the near wall residence times and shear exposure in a 45 degrees anastomosis under symmetrical and symmetry breaking geometric configurations. We define residence time as the minimum time for a particle to exit a spherical region and shear exposure as a temporal integral of the Huber-Henky-von-Mises criterion along a particle path over a fixed time interval. Decomposing the pulsatile cycle into four equal intervals we find that the interval of peak residence time in the host vessel is from mid-deceleration to peak diastole and peak diastole to mid-acceleration. The asymmetric model is shown to have a significantly lower residence time during these intervals. Considering the shear exposure prior to the residence time evaluation we determine that a higher average shear exposure exists in the asymmetric model associated with the upstream geometry modification. Analysis of the regions of high residence time and shear exposure suggests that the "toe" region and the interface between the "heel" and bulk flow are more significant than the bed and heel region. Although the asymmetric model considered in this study reduces residence times in the host artery, the product of the measure of shear exposure and residence time is not found to be preferable. If shear exposure were to be considered as an important factor in particle activation, the findings imply that for junction optimisation, greater consideration needs to be given both to the local junction asymmetry and upstream influence on the shear history. PMID:12122254

  16. The timing of exposure in clinic-based treatment for childhood anxiety disorders.

    PubMed

    Gryczkowski, Michelle R; Tiede, Michael S; Dammann, Julie E; Jacobsen, Amy Brown; Hale, Lisa R; Whiteside, Stephen P H

    2013-03-01

    The present study examines treatment length and timing of exposure from two child anxiety disorders clinics. Data regarding symptoms and treatment characteristics for 28 youth were prospectively obtained through self, parent, and therapist report at each session. Information regarding length of treatment, timing of exposure initiation, and drop-out rates were compared with those obtained through efficacy and effectiveness trials of manualized treatment for anxious youth. Findings from the authors' clinical data revealed significantly shorter treatment duration with exposures implemented sooner than in the previous studies. Dropout rates were significantly higher than in the efficacy trial but comparable with the effectiveness trial. Outcome data from a subset of eight patients revealed large effect sizes. These findings suggest that effective treatment can be shorter and more focused on exposure than is often outlined in manuals and have important implications for outcome research and dissemination. PMID:23548341

  17. The timing of exposure in clinic-based treatment for childhood anxiety disorders.

    PubMed

    Gryczkowski, Michelle R; Tiede, Michael S; Dammann, Julie E; Brown Jacobsen, Amy; Hale, Lisa R; Whiteside, Stephen P H

    2013-01-01

    The present study examines treatment length and timing of exposure from two child anxiety disorders clinics. Data regarding symptoms and treatment characteristics for 28 youth were prospectively obtained through self, parent, and therapist report at each session. Information regarding length of treatment, timing of exposure initiation, and drop-out rates were compared with those obtained through efficacy and effectiveness trials of manualized treatment for anxious youth. Findings from the authors' clinical data revealed significantly shorter treatment duration with exposures implemented sooner than in the previous studies. Dropout rates were significantly higher than in the efficacy trial but comparable with the effectiveness trial. Outcome data from a subset of eight patients revealed large effect sizes. These findings suggest that effective treatment can be shorter and more focused on exposure than is often outlined in manuals and have important implications for outcome research and dissemination. PMID:23012686

  18. Research plan for establishing the effects of time varying noise exposures on community annoyance and acceptability

    NASA Technical Reports Server (NTRS)

    Borsky, P. N.

    1980-01-01

    The design of a community noise survey to determine the effects of time varying noise exposures in residential communities is presented. Complex physical and human variables involved in the health and welfare effects of environmental noise and the number-level tradeoffs and time of day penalties are among the factors considered. Emphasis is placed on community reactions where noise exposures are equal in day or evening but differ in the night time, and the effects of ambient noise on more intense aircraft noise exposures. Thirteen different times of day and types of operation situations with exposed populations up to 8-10 miles from the airport are identified. A detailed personal interview questionnaire as well as specific instructions to interviewers are included.

  19. Investigating the American Time Use Survey from an Exposure Modeling Perspective

    EPA Science Inventory

    This paper describes an evaluation of the U.S. Bureau of Labor Statistics' American Time Use Survey (ATUS) for potential use in modeling human exposures to environmental pollutants. The ATUS is a large, on-going, cross-sectional survey of where Americans spend time and what activ...

  20. Recurrent studies of chloride ingress in uncracked marine concrete at various exposure times and elevations

    SciTech Connect

    Sandburg, P. [Lund Inst. of Tech. (Sweden). Div. of Building Materials] [Lund Inst. of Tech. (Sweden). Div. of Building Materials; Tang, L. [Swedish National Testing and Research Inst., Boraes (Sweden)] [Swedish National Testing and Research Inst., Boraes (Sweden); Andersen, A. [Chalmers Univ., Goeteborg (Sweden). Div. of Building Materials] [Chalmers Univ., Goeteborg (Sweden). Div. of Building Materials

    1998-10-01

    Uncracked reinforced concrete slabs were field exposed mounted on a floating pontoon and partly submerged for 5 years at the Swedish west coast. The total chloride ingress was analyzed at various exposure times at 3 elevations representing a submerged, a splash, and an atmospheric exposure zone. The concrete mixtures varied in w/c ratio, type of cement, and amount and type of pozzolan used in the binder. The data is unique as it represents recurrently measured total chloride penetration profiles at various exposure ages, providing a foundation for the prediction of chloride ingress in concrete in a given environment. The results after 5 years of exposure confirmed the expected inverse relationship between water-to-binder ratio and chloride ingress. The use of 5--10% silica fume in the binder had a very positive effect on reducing the chloride ingress, but little or no benefit at all was found for concrete with fly ash in the binder as compared to the use of 5% silica fume. The chloride penetration rate as expressed by a calculated effective chloride diffusivity has a tendency to decrease over time. High-performance concrete with w/c {le} 0.4 and a minimum of 5% silica fume added as a well dispersed slurry exhibited an effective chloride diffusivity in the range of 1 {times} 10{sup {minus}13} to 5 {times} 10{sup {minus}13} m{sup 2}/s after 5 years exposure in the splash zone.

  1. Analysis of indoor PM2.5 exposure in Asian countries using time use survey.

    PubMed

    Shimada, Yoko; Matsuoka, Yuzuru

    2011-11-15

    Most household fuels used in Asian countries are solid fuels such as coal and biomass (firewood, crop residue and animal dung). The particulate matter (PM), CO, NOx and SOx produced through the combustion of these fuels inside the residence for cooking and heating has an adverse impact on people's health. PM 2.5 in particular, consisting of particles with an aerodynamic diameter of 2.5 ?m or less, penetrates deep into the lungs and causes respiratory system and circulatory system diseases and so on. As a result, the World Health Organization (WHO) established guideline values for this type of particulate matter in 2005. In this study, the authors focused on PM 2.5 and estimated indoor exposure concentrations for PM 2.5 in 15 Asian countries. For each environment used for cooking, eating, heating and illumination in which people are present temporarily (microenvironment), exposure concentrations were estimated for individual cohorts categorized according to sex, age and occupation status. To establish the residence time in each microenvironment for each of the cohorts, data from time use surveys conducted in individual countries were used. China had the highest estimate for average exposure concentration in microenvironment used for cooking at 427.5 ?g/m3, followed by Nepal, Laos and India at 285.2 ?g/m3, 266.3 ?g/m3 and 205.7 ?g/m3, respectively. The study found that, in each country, the PM2.5 exposure concentration was highest for children and unemployed women between the ages of 35 and 64. The study also found that the exposure concentration for individual cohorts in each country was greatly affected by people's use of time indoors. Because differences in individual daily life activities were reflected in the use of time and linked to an assessment of exposure to indoor air-polluting substances, the study enabled detailed assessment of the impact of exposure. PMID:21944197

  2. Distinct neurobehavioral dysfunction based on the timing of developmental binge-like alcohol exposure.

    PubMed

    Sadrian, B; Lopez-Guzman, M; Wilson, D A; Saito, M

    2014-11-01

    Gestational exposure to alcohol can result in long-lasting behavioral deficiencies generally described as fetal alcohol spectrum disorder (FASD). FASD-modeled rodent studies of acute ethanol exposure typically select one developmental window to simulate a specific context equivalent of human embryogenesis, and study consequences of ethanol exposure within that particular developmental epoch. Exposure timing is likely a large determinant in the neurobehavioral consequence of early ethanol exposure, as each brain region is variably susceptible to ethanol cytotoxicity and has unique sensitive periods in their development. We made a parallel comparison of the long-term effects of single-day binge ethanol at either embryonic day 8 (E8) or postnatal day 7 (P7) in male and female mice, and here demonstrate the differential long-term impacts on neuroanatomy, behavior and in vivo electrophysiology of two systems with very different developmental trajectories. The significant long-term differences in odor-evoked activity, local circuit inhibition, and spontaneous coherence between brain regions in the olfacto-hippocampal pathway that were found as a result of developmental ethanol exposure, varied based on insult timing. Long-term effects on cell proliferation and interneuron cell density were also found to vary by insult timing as well as by region. Finally, spatial memory performance and object exploration were affected in P7-exposed mice, but not E8-exposed mice. Our physiology and behavioral results are conceptually coherent with the neuroanatomical data attained from these same mice. Our results recognize both variable and shared effects of ethanol exposure timing on long-term circuit function and their supported behavior. PMID:25241068

  3. Percutaneous toxicity of uranyl nitrate: its effect in terms of exposure area and time.

    PubMed

    López, R; Díaz Sylvester, P L; Ubios, A M; Cabrini, R L

    2000-04-01

    Different groups have undertaken research work focusing their attention on the biological effects of uranium and have described kidney and bone to be the main target organs in uranium poisoning. In this study we used the skin as the route of entry of uranium. We carried out two sets of experiments in adult rats: in one of them topical applications with uranyl nitrate (UN) over different areas were performed; in the other topical applications with UN on a given area over different times were carried out. In the latter experiment the exposure to UN was stopped by removing it from skin with soap and water. Kidney and bone samples were removed for histological studies. This work is based on the determination of the survival rate of the exposed animals and on the effects elicited in kidney and bone. There is a relation between the area of the surface exposed to uranium and the time of exposure and the subsequent percutaneous toxicity. There were no surviving animals following topical application of UN to an 8 cm2 area nor when the time of exposure was 24 h. The survival rate of the animals increased when either the topical area or the time of exposure to UN was reduced. Although the inhibition of bone formation in metaphysical bone has been previously described by our group as a result of UN poisoning, this is the first time that such an effect is found after percutaneous exposure for such short periods of time. The general toxic effects of UN, evidenced as kidney histological alterations, increased in severity as either one of the two variables studied increased. This is a condition that could be considered as hazardous for those workers engaged in uranium processing and purification. It is noteworthy that a simple method such as washing with soap and water is an effective method to reduce the lethality of UN percutaneous intoxication. PMID:10749526

  4. Measures of patient radiation exposure during endoscopic retrograde cholangiography: Beyond fluoroscopy time

    PubMed Central

    Kachaamy, Toufic; Harrison, Edwyn; Pannala, Rahul; Pavlicek, William; Crowell, Michael D; Faigel, Douglas O

    2015-01-01

    AIM: To determine whether fluoroscope time is a good predictor of patient radiation exposure during endoscopic retrograde cholangiopancreatography. METHODS: This is a prospective observational study of consecutive patients undergoing endoscopic retrograde cholangiopancreatography in a tertiary care setting. Data related to radiation exposure were collected. The following measures were obtained: Fluoroscopy time (FT), dose area product (DAP) and dose at reference point (DOSERP). Coefficients of determination were calculated to analyze the correlation between FT, DAP and DOSRP. Agreement between FT and DAP/DOSRP was assessed using Bland Altman plots. RESULTS: Four hundred sixty-three data sets were obtained. Fluoroscopy time average was 7.3 min. Fluoroscopy related radiation accounted for 86% of the total DAP while acquisition films related radiation accounted for 14% of the DAP. For any given FT there are wide ranges of DAP and DOSERP and the variability in both increases as fluoroscopy time increases. The coefficient of determination (R2) on the non transformed data for DAP and DOSERP versus FT were respectively 0.416 and 0.554. While fluoroscopy use was the largest contributor to patient radiation exposure during endoscopic retrograde cholangiography (ERCP), there is a wide variability in DAP and DOSERP that is not accounted for by FT. DAP and DOSERP increase in variability as FT increases. This translates into poor accuracy of FT in predicting DAP and DOSERP at higher radiation doses. CONCLUSION: DAP and DOSERP in addition to FT should be adopted as new ERCP quality measures to estimate patient radiation exposure. PMID:25684958

  5. Color, dispersion, and exposure time in performance on rotated figure recognition.

    PubMed

    Huang, Kuo-Chen; Lee, Shin-Tsann; Chang, Chun-Chieh

    2008-10-01

    This study investigated the effects of dispersion, color, and rotation of figures on recognition under varied exposure times. A total of 30 women and 15 men, Taiwanese college students ages 18 to 20 years (M = 19.1, SD = 1.2), participated. Subjects were to recognize a target figure and respond with its location in each stimulus by pressing a mouse button. Analysis showed that the effect of rotation on accuracy was significant. Accuracy for the rotation of 180 degrees was greater than those for 60 degrees and 300 degrees. Exposure time also significantly influenced accuracy. The accuracy was greater for 2 and 3 sec. than for 1 sec. No significant effects on accuracy were associated with dispersion and color, and neither had any interactive effect on accuracy. Dispersion significantly affected the response time as response time for dispersion under 0.4 and 0.5 conditions were shorter than those under 0.2 and 0.3 conditions. Significantly less response time was needed for rotation of 180 degrees than for 60 degrees and 300 degrees conditions. Response time was longer for red figures than for blue, green, and yellow figures. No significant effect on response time was associated with duration of exposure. Two interactive two-way effects were found: dispersion x color of figure and dispersion x rotation. Implications for figure or icon design are discussed. PMID:19093616

  6. Changes of polybrominated diphenyl ether concentrations in ducks with background exposure level and time.

    PubMed

    Liu, Peng-Yan; Chen, Xiao-Ran; Zhao, Ya-Xian; Li, Yuan-Yuan; Qin, Xiao-Fei; Qin, Zhan-Fen

    2015-01-01

    To reveal what degree bioaccumulation of polybrominated diphenyl ethers (PBDEs) depends on exposure time and other factors, we conducted a semi-field experiment for a year (June 2008-June 2009) in a village in an e-waste recycling site in Taizhou, China. Approximately one hundred of juvenile ducks (Anas domestica Linnaeus) were entrusted to a villager. The ducks lived and forged in a PBDE-polluted pond from the late March to the end of November. Fish and mudsnails that were heavily polluted by PBDEs were main food. In cold days (from December to the middle March), the ducks lived in the villager' house, and mainly fed on paddy, which contained lower concentrations of PBDEs than fish and mudsnails. The female ducks were sampled for PBDE analysis every three months. We found that the ?PBDE concentrations in duck liver, muscle, lung and brain fluctuated greatly with the changes of exposure levels that were determined by the environment and diets, but the ?PBDE concentrations in fat tissue increased successively with time. Congener analysis demonstrated that the successive increase in the ?PBDE concentrations with time in fat tissue was due to the successive increase in BDE-209, -183 and -153 concentrations, with large fluctuations of low brominated congeners. The results show that PBDE concentrations in liver, muscle, lung and brain tissues heavily depends on exposure levels rather than exposure time. In fat tissue, by contrast, PBDE concentrations (mainly high brominated congeners) slightly depends on exposure levels but heavily depend on time relative to other tissues, implying that high brominated congeners seem to have longer half-lives than low brominated congeners in fat tissue. PMID:25290171

  7. Effect Modification of the Association of Cumulative Exposure and Cancer Risk by Intensity of Exposure and Time Since Exposure Cessation: A Flexible Method Applied to Cigarette Smoking and Lung Cancer in the SYNERGY Study

    PubMed Central

    Vlaanderen, Jelle; Portengen, Lützen; Schüz, Joachim; Olsson, Ann; Pesch, Beate; Kendzia, Benjamin; Stücker, Isabelle; Guida, Florence; Brüske, Irene; Wichmann, Heinz-Erich; Consonni, Dario; Landi, Maria Teresa; Caporaso, Neil; Siemiatycki, Jack; Merletti, Franco; Mirabelli, Dario; Richiardi, Lorenzo; Gustavsson, Per; Plato, Nils; Jöckel, Karl-Heinz; Ahrens, Wolfgang; Pohlabeln, Hermann; Tardón, Adonina; Zaridze, David; Field, John K.; 't Mannetje, Andrea; Pearce, Neil; McLaughlin, John; Demers, Paul; Szeszenia-Dabrowska, Neonila; Lissowska, Jolanta; Rudnai, Peter; Fabianova, Eleonora; Stanescu Dumitru, Rodica; Bencko, Vladimir; Foretova, Lenka; Janout, Vladimir; Boffetta, Paolo; Forastiere, Francesco; Bueno-de-Mesquita, Bas; Peters, Susan; Brüning, Thomas; Kromhout, Hans; Straif, Kurt; Vermeulen, Roel

    2014-01-01

    The indiscriminate use of the cumulative exposure metric (the product of intensity and duration of exposure) might bias reported associations between exposure to hazardous agents and cancer risk. To assess the independent effects of duration and intensity of exposure on cancer risk, we explored effect modification of the association of cumulative exposure and cancer risk by intensity of exposure. We applied a flexible excess odds ratio model that is linear in cumulative exposure but potentially nonlinear in intensity of exposure to 15 case-control studies of cigarette smoking and lung cancer (1985–2009). Our model accommodated modification of the excess odds ratio per pack-year of cigarette smoking by time since smoking cessation among former smokers. We observed negative effect modification of the association of pack-years of cigarette smoking and lung cancer by intensity of cigarette smoke for persons who smoked more than 20–30 cigarettes per day. Patterns of effect modification were similar across individual studies and across major lung cancer subtypes. We observed strong negative effect modification by time since smoking cessation. Application of our method in this example of cigarette smoking and lung cancer demonstrated that reducing a complex exposure history to a metric such as cumulative exposure is too restrictive. PMID:24355332

  8. Effect modification of the association of cumulative exposure and cancer risk by intensity of exposure and time since exposure cessation: a flexible method applied to cigarette smoking and lung cancer in the SYNERGY Study.

    PubMed

    Vlaanderen, Jelle; Portengen, Lützen; Schüz, Joachim; Olsson, Ann; Pesch, Beate; Kendzia, Benjamin; Stücker, Isabelle; Guida, Florence; Brüske, Irene; Wichmann, Heinz-Erich; Consonni, Dario; Landi, Maria Teresa; Caporaso, Neil; Siemiatycki, Jack; Merletti, Franco; Mirabelli, Dario; Richiardi, Lorenzo; Gustavsson, Per; Plato, Nils; Jöckel, Karl-Heinz; Ahrens, Wolfgang; Pohlabeln, Hermann; Tardón, Adonina; Zaridze, David; Field, John K; 't Mannetje, Andrea; Pearce, Neil; McLaughlin, John; Demers, Paul; Szeszenia-Dabrowska, Neonila; Lissowska, Jolanta; Rudnai, Peter; Fabianova, Eleonora; Stanescu Dumitru, Rodica; Bencko, Vladimir; Foretova, Lenka; Janout, Vladimir; Boffetta, Paolo; Forastiere, Francesco; Bueno-de-Mesquita, Bas; Peters, Susan; Brüning, Thomas; Kromhout, Hans; Straif, Kurt; Vermeulen, Roel

    2014-02-01

    The indiscriminate use of the cumulative exposure metric (the product of intensity and duration of exposure) might bias reported associations between exposure to hazardous agents and cancer risk. To assess the independent effects of duration and intensity of exposure on cancer risk, we explored effect modification of the association of cumulative exposure and cancer risk by intensity of exposure. We applied a flexible excess odds ratio model that is linear in cumulative exposure but potentially nonlinear in intensity of exposure to 15 case-control studies of cigarette smoking and lung cancer (1985-2009). Our model accommodated modification of the excess odds ratio per pack-year of cigarette smoking by time since smoking cessation among former smokers. We observed negative effect modification of the association of pack-years of cigarette smoking and lung cancer by intensity of cigarette smoke for persons who smoked more than 20-30 cigarettes per day. Patterns of effect modification were similar across individual studies and across major lung cancer subtypes. We observed strong negative effect modification by time since smoking cessation. Application of our method in this example of cigarette smoking and lung cancer demonstrated that reducing a complex exposure history to a metric such as cumulative exposure is too restrictive. PMID:24355332

  9. Time course of bronchial cell inflammation following exposure to diesel particulate matter using a modified EAVES.

    PubMed

    Hawley, Brie; McKenna, Dave; Marchese, Anthony; Volckens, John

    2014-08-01

    Electrostatic deposition of particles onto the surface of well-differentiated airway cells is a rapid and efficient means to screen for toxicity associated with exposure to fine and ultrafine particulate air pollution. This work describes the development and application of an electrostatic aerosol in vitro exposure system (EAVES) with increased throughput and ease-of-use. The modified EAVES accommodates standard tissue culture plates and uses an alternating electric field to deposit a net neutral charge of aerosol onto air-interface cell cultures. Using this higher-throughput design, we were able to examine the time-course (1, 3, 6, 9, and 24 h post-exposure) of transcript production and cytotoxicity in well-differentiated human bronchial cells exposed to diesel particulate matter at levels of 'real-world' significance. Statistically significant responses were observed at exposure levels (?0.4 ?g/cm(2)) much lower than typically reported in vitro using traditional submerged/resuspended techniques. Levels of HO-1, IL-8, CYP1A1, COX-2, and HSP-70 transcripts increased immediately following diesel particulate exposure and persisted for several hours; cytotoxicity was increased at 24h. The modified EAVES provides a platform for higher throughput, more efficient and representative testing of aerosol toxicity in vitro. PMID:24681185

  10. Developmental timing of sodium perchlorate exposure alters angiogenesis, thyroid follicle proliferation and sexual maturation in stickleback.

    PubMed

    Furin, Christoff G; von Hippel, Frank A; Postlethwait, John H; Buck, C Loren; Cresko, William A; O'Hara, Todd M

    2015-08-01

    Perchlorate, a common aquatic contaminant, is well known to disrupt homeostasis of the hypothalamus-pituitary-thyroid axis. This study utilizes the threespine stickleback (Gasterosteus aculeatus) fish to determine if perchlorate exposure during certain windows of development has morphological effects on thyroid and gonads. Fish were moved from untreated water to perchlorate-contaminated water (30 and 100mg/L) starting at 0, 3, 7, 14, 21, 42, 154 and 305days post fertilization until approximately one year old. A reciprocal treatment (fish in contaminated water switched to untreated water) was conducted on the same schedule. Perchlorate exposure increased angiogenesis and follicle proliferation in thyroid tissue, delayed gonadal maturity, and skewed sex ratios toward males; effects depended on concentration and timing of exposure. This study demonstrates that perchlorate exposure beginning during the first 42days of development has profound effects on stickleback reproductive and thyroid tissues, and by implication can impact population dynamics. Long-term exposure studies that assess contaminant effects at various stages of development provide novel information to characterize risk to aquatic organisms, to facilitate management of resources, and to determine sensitive developmental windows for further study of underlying mechanisms. PMID:25865142

  11. Timing matters: sensitivity of Daphnia magna dormant eggs to fenoxycarb exposure depends on embryonic developmental stage.

    PubMed

    Navis, Sabine; Waterkeyn, Aline; Putman, Adinda; De Meester, Luc; Vanermen, Guido; Brendonck, Luc

    2015-02-01

    Although Daphnia magna is a key species in many lentic freshwater ecosystems and is commonly used as model organism in ecology and ecotoxicology, very little is known about the effects of chemicals on their dormant life stages. Dormant eggs (ephippia) are produced when environmental conditions deteriorate, and Daphnia switch from clonal to sexual reproduction. Ephippia produced over different growing seasons can accumulate in the sediment of ponds and lakes, where they can be exposed to pesticides and other (anthropogenic) stressors. In the present study, we have investigated the effects of pesticide exposure on dormant eggs at different embryonic developmental stages and evaluated the degree of protection against pollution provided by the ephippial case. We therefore conducted a hatching experiment in which decapsulated and encapsulated dormant eggs were exposed to an insect growth regulator (fenoxycarb) at different stages during their development, both before and after activation of the eggs. In addition, we developed an analytical method to measure fenoxycarb concentrations in the dormant eggs. Fenoxycarb negatively affected development and hatching success and changed the timing of hatching in activated and in dormant eggs. Hatching characteristics as well as fenoxycarb concentrations inside the eggs differed significantly between exposure treatments. Final stages of embryonic development were most sensitive to pesticide exposure and had the highest tissue concentrations of fenoxycarb. Tissue concentrations did not differ significantly between decapsulated and encapsulated eggs, suggesting that the ephippial case offers limited or no direct protection against pesticide exposure. With this study we provide new evidence showing that pesticides can bioconcentrate in and affect D. magna dormant eggs. The severity of the effects on developing embryos depends on the timing of pesticide exposure. Our results stress the importance of considering the full life-cycle of model organisms used in ecotoxicological studies, since these are ultimately aimed at assessing risks of chemical exposure on natural aquatic ecosystems. PMID:25546008

  12. Time course of permeability changes and PMN flux in rat trachea following O3 exposure

    SciTech Connect

    Young, C.; Bhalla, D.K. (Community and Environmental Medicine, University of California, Irvine (United States))

    1992-02-01

    Changes in rat tracheal epithelial permeability and polymorphonuclear leukocyte (PMN) populations during a 24-hr time period following a 3-hr exposure to 0.8 ppm ozone (O3) were investigated. An increase in permeability to 99mTc-diethylene-triaminepentaacetate (DTPA) occurred immediately after the exposure, peaked at the 8-hr time point and decreased to control level by 24 hr. For correlation with tracheal permeability, tracheal cross sections were stained with naphthol AS-D chloroacetate and PMNs were scored by their location as well as staining characteristics (positive or negative). The total PMN population remained at the control value at the 0-, 4-, and 8-hr time points, and increased at 12 hr, followed by a rapid decline to below the control value for the remaining time points. There was a shift at the 8-hr time point in the population location, from the vasculature to the interstitium, which returned to control values at 12 hr. The percentage stained PMNs increased significantly at 16 hr while remaining at control values for all other time points. The data reveal that there is a significant increase in tracheal epithelial permeability immediately after the exposure, but the overall increase in the PMN population is preceded by a lag phase. A decrease in the vascular pool of PMNs concomitant with an increase in the interstitial pool of PMNs suggests their migration from blood to the interstitium after ozone exposure. These data indicate that while PMNs may play a role in permeability changes of tracheal epithelium, the initiation is most likely due to other factors.

  13. Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure

    NASA Technical Reports Server (NTRS)

    Duffy, J. F.; Kronauer, R. E.; Czeisler, C. A.

    1996-01-01

    1. Both the timing of behavioural events (activity, sleep and social interactions) and the environmental light-dark cycle have been reported to contribute to entrainment of human circadian rhythms to the 24 h day. Yet, the relative contribution of those putative behavioural synchronizers to that of light exposure remains unclear. 2. To investigate this, we inverted the schedule of rest, sedentary activity and social contact of thirty-two young men either with or without exposure to bright light. 3. On this inverted schedule, the endogenous component of the core temperature rhythm of subjects who were exposed to bright light showed a significant phase shift, demonstrating that they were adapting to the new schedule. In contrast, the core temperature rhythm of subjects who were not exposed to bright light moved on average 0.2 h later per day and after 10 days had not significantly adapted to the new schedule. 4. The direction of phase shift in the groups exposed to bright light was dependent on the time of bright light exposure, while control subjects drifted to a later hour regardless of the timing of their schedule of sleep timing, social contact and meals. 5. These results support the concept that the light-dark cycle is the most important synchronizer of the human circadian system. They suggest that inversion of the sleep-wake, rest-activity and social contact cycles provides relatively minimal drive for resetting the human circadian pacemaker. 6. These data indicate that interventions designed to phase shift human circadian rhythms for adjustment to time zone changes or altered work schedules should focus on properly timed light exposure.

  14. Effects of mobile phone exposure on time frequency fine structure of transiently evoked otoacoustic emissions.

    PubMed

    Paglialonga, Alessia; Tognola, Gabriella; Parazzini, Marta; Lutman, Mark E; Bell, Steven L; Thuroczy, Gyorgy; Ravazzani, Paolo

    2007-10-01

    Mobile phones have become very commonly used worldwide within a short period of time. To date there is only limited knowledge about interaction between electromagnetic fields (EMFs) emitted by mobile phones and the auditory function. Moreover, there is widespread concern that there may be potential for harm. The aim of this study was to assess potential subtle changes in cochlear function by measuring the temporal and spectral fine structure of transiently evoked otoacoustic emissions (TEOAE) in normal hearing subjects after exposure to EMFs emitted by Global System for Mobile Communication (GSM) mobile phones. TEOAEs were recorded in 27 healthy young adults before and after 10 min of real or sham exposure in a double-blind design. TEOAE data were analyzed both globally (broadband analysis) and using the Wavelet Transform (analysis of the time-frequency fine structure). The broadband analysis revealed no significant effect on TEOAEs related to exposure, confirming results of previous studies; in addition, no significant change was detected in the analysis of the elementary wavelet components, suggesting that the temporal and spectral fine structure of TEOAEs is not affected by 10 min exposure to low-intensity EMFs emitted by GSM mobile phones. PMID:17902853

  15. Personal day-time exposure to ultrafine particles in different microenvironments.

    PubMed

    Gu, Jianwei; Kraus, Ute; Schneider, Alexandra; Hampel, Regina; Pitz, Mike; Breitner, Susanne; Wolf, Kathrin; Hänninen, Otto; Peters, Annette; Cyrys, Josef

    2015-03-01

    In order to assess the personal exposure to ultrafine particles (UFP) during individual day-time activities and to investigate the impact of different microenvironments on exposure, we measured personal exposure to particle number concentrations (PNC), a surrogate for UFP, among 112 non-smoking participants in Augsburg, Germany over a nearly two-year period from March 2007 to December 2008. We obtained 337 personal PNC measurements from 112 participants together with dairies of their activities and locations. The measurements lasted on average 5.5h and contained on average 330 observations. In addition, ambient PNC were measured at an urban background stationary monitoring site. Personal PNC were highly variable between measurements (IQR of mean: 11780-24650cm(-3)) and also within a single measurement. Outdoor personal PNC in traffic environments were about two times higher than in non-traffic environments. Higher indoor personal PNC were associated with activities like cooking, being in a bistro or exposure to passive smoking. Overall, personal and stationary PNC were weakly to moderately correlated (r<0.41). Personal PNC were much higher than stationary PNC in traffic (ratio: 1.5), when shopping (ratio: 2.4), and indoors with water vapor (ratio: 2.5). Additive mixed models were applied to predict personal PNC by participants' activities and locations. Traffic microenvironments were significant determinants for outdoor personal PNC. Being in a bistro, passive smoking, and cooking contributed significantly to an increased indoor personal PNC. PMID:25458919

  16. An examination of exposure measurement error from air pollutant spatial variability in time-series studies.

    PubMed

    Sarnat, Stefanie E; Klein, Mitchel; Sarnat, Jeremy A; Flanders, W Dana; Waller, Lance A; Mulholland, James A; Russell, Armistead G; Tolbert, Paige E

    2010-03-01

    Relatively few studies have evaluated the effects of heterogeneous spatiotemporal pollutant distributions on health risk estimates in time-series analyses that use data from a central monitor to assign exposures. We present a method for examining the effects of exposure measurement error relating to spatiotemporal variability in ambient air pollutant concentrations on air pollution health risk estimates in a daily time-series analysis of emergency department visits in Atlanta, Georgia. We used Poisson generalized linear models to estimate associations between current-day pollutant concentrations and circulatory emergency department visits for the 1998-2004 time period. Data from monitoring sites located in different geographical regions of the study area and at different distances from several urban geographical subpopulations served as alternative measures of exposure. We observed associations for spatially heterogeneous pollutants (CO and NO(2)) using data from several different urban monitoring sites. These associations were not observed when using data from the most rural site, located 38 miles from the city center. In contrast, associations for spatially homogeneous pollutants (O(3) and PM(2.5)) were similar, regardless of the monitoring site location. We found that monitoring site location and the distance of a monitoring site to a population of interest did not meaningfully affect estimated associations for any pollutant when using data from urban sites located within 20 miles from the population center under study. However, for CO and NO(2), these factors were important when using data from rural sites located > or = 30 miles from the population center, most likely owing to exposure measurement error. Overall, our findings lend support to the use of pollutant data from urban central sites to assess population exposures within geographically dispersed study populations in Atlanta and similar cities. PMID:19277071

  17. In-situ real time measurements of net erosion rates of copper during hydrogen plasma exposure

    NASA Astrophysics Data System (ADS)

    Kesler, Leigh; Wright, Graham; Peterson, Ethan; Whyte, Dennis

    2013-10-01

    In order to properly understand the dynamics of net erosion/deposition in fusion reactors, such as tokamaks, a diagnostic measuring the real time rates of net erosion/deposition during plasma exposure is necessary. The DIONISOS experiment produces real time measurements of net erosion/deposition by using Rutherford backscattering spectroscopy (RBS) ion beam analysis simultaneously with plasma exposure from a helicon plasma source. This in-situ method improves on ex-situ weight loss measurements by allowing measurement of possible synergistic effects of high ion implantation rates and net erosion rate and by giving a real time response to changes in plasma parameters. Previous work has validated this new technique for measuring copper (Cu) erosion from helium (He) plasma ion bombardment. This technique is now extended to measure copper erosion due to deuterium and hydrogen plasma ion exposure. Targets used were a 1.5 ?m Cu layer on an aluminum substrate. Cu layer thickness is tracked in real time using 1.2 MeV proton RBS. Measured erosion rates will be compared to results from literature and He erosion rates. Supported by US DoE award DE-SC00-02060.

  18. Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry

    NASA Technical Reports Server (NTRS)

    Decker, A. J.

    1984-01-01

    The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed.

  19. Measurement of fluid properties using rapid-double-exposure and time-average holographic interferometry

    NASA Technical Reports Server (NTRS)

    Decker, A. J.

    1984-01-01

    The holographic recording of the time history of a flow feature in three dimensions is discussed. The use of diffuse illumination holographic interferometry or the three-dimensional visualization of flow features such as shock waves and turbulent eddies is described. The double-exposure and time-average methods are compared using the characteristic function and the results from a flow simulator. A time history requires a large hologram recording rate. Results of holographic cinematography of the shock waves in a flutter cascade are presented as an example. Future directions of this effort, including the availability and development of suitable lasers, are discussed. Previously announced in STAR as N84-21849

  20. Breast cancer risk after occupational solvent exposure: the influence of timing and setting

    PubMed Central

    Ekenga, Christine C; Parks, Christine G.; D’Aloisio, Aimee A.; DeRoo, Lisa A.; Sandler, Dale P.

    2014-01-01

    Organic solvents are ubiquitous in occupational settings where they may contribute to risks for carcinogenesis. However, there is limited information on organic solvents as human breast carcinogens. We examined the relationship between occupational exposure to solvents and breast cancer in a prospective study of 47,661 women with an occupational history in the Sister Study cohort. Occupational solvent exposure was categorized using self-reported job-specific solvent use collected at baseline. Multivariable Cox regression analyses were used to assess breast cancer risk, adjusting for established breast cancer risk factors. A total of 1,798 women were diagnosed with breast cancer during follow-up, including 1,255 invasive cases. Overall, the risk of invasive breast cancer was not associated with lifetime exposure to solvents (HR: 1.04; 95% CI = 0.88–1.24). Parous women who worked with solvents prior to their first full-term birth had an increased risk of estrogen receptor-positive invasive breast cancer compared to women who never worked with solvents (HR: 1.39; 95% CI = 1.03–1.86). A significantly elevated risk for estrogen receptor-positive invasive breast cancer was associated with solvent exposure among clinical laboratory technologists and technicians (HR: 2.00; 95%CI: 1.07–3.73). Occupational exposure to solvents prior to first birth, a critical period of breast tissue differentiation, may result in increased vulnerability for breast cancer. Our findings suggest a need for future studies in this area to focus on exposure time windows and solvent types in different occupational settings. PMID:24879566

  1. Effects of exposure time during flight maneuvers on passenger subjective comfort rating

    NASA Technical Reports Server (NTRS)

    Brown, V. J.

    1975-01-01

    The effects were investigated of length of exposure time to a flight maneuver environment on subjective passenger evaluation of ride comfort. Four statistical analysis tests were performed on ride comfort ratings obtained during one two-hour test flight wherein eleven test subjects were exposed to two identical programmed sequences of twenty four flight segments which covered a wide range of maneuver conditions. The results of the analysis indicate that, for over ninety five percent of the segments, there is no significant change in the test subjects comfort ratings of identical segments spaced one hour apart. These results are in contrast to those found in previous studies involving a vibration environment, rather than flight maneuver environment, where increased exposure-time was found to cause a degradation of ride comfort ratings.

  2. An examination of exposure measurement error from air pollutant spatial variability in time-series studies

    PubMed Central

    Sarnat, Stefanie E.; Klein, Mitchel; Sarnat, Jeremy A.; Flanders, W. Dana; Waller, Lance A.; Mulholland, James A.; Russell, Armistead G.; Tolbert, Paige E.

    2013-01-01

    Introduction Relatively few studies have evaluated the impacts of heterogeneous spatiotemporal pollutant distributions on health risk estimates in time-series analyses that use data from a central monitor to assign exposures. We present a method for examining the impacts of exposure measurement error relating to spatiotemporal variability in ambient air pollutant concentrations on air pollution health risk estimates in a daily time-series analysis of emergency department visits in Atlanta, Georgia. Methods We used Poisson generalized linear models to estimate associations between current day pollutant concentrations and circulatory emergency department visits for the 1998–2004 period. Data from monitoring sites located in different geographical regions of the study area and at different distances from several urban geographic subpopulations served as alternative measures of exposure. Results We observed associations for spatially heterogeneous pollutants (CO and NO2) using data from several different urban monitoring sites. These associations were not observed when using data from the most rural site, located 38 miles from the city center. In contrast, associations for spatially homogeneous pollutants (O3 and PM2.5) were similar regardless of monitoring site location. Conclusions We found that monitoring site location and the distance of a monitoring site to a population of interest did not meaningfully impact estimated associations for any pollutant when using data from urban sites located within 20 miles from the population center under study. However, for CO and NO2, these factors were important when using data from rural sites, located greater than 30 miles from the population center, likely due to exposure measurement error. Overall, our findings lend support to the use of pollutant data from urban central sites to assess population exposures within geographically dispersed study populations in Atlanta and similar cities. PMID:19277071

  3. Using tensor product splines in modeling exposure-time-response relationships: application to the Colorado Plateau Uranium Miners cohort.

    PubMed

    Berhane, Kiros; Hauptmann, Michael; Langholz, Bryan

    2008-11-20

    An adequate depiction of exposure-time-response relationships is important in assessing public health implications of an occupational or environmental exposure. Recent advances have focused on flexible modeling of the overall shape of latency. Methods are needed to allow for varying shapes of latency under different exposure profiles. A tensor product spline model is proposed for describing exposure-response relationships for protracted time-dependent occupational exposure histories in epidemiologic studies. The methods use flexible multi-dimensional techniques to jointly model age, latency and exposure-response effects. In analyzing data from the Colorado Plateau Uranium Miners cohort, a model that allows for varying exposure-dependent latency shapes is found to be superior to models that only allowed for an overall latency curve. Specifically, the model suggests that, at low exposure levels risk increased at short latencies followed by a slow decline for longer latency periods. On the other hand, risk was higher but did not change much by latency for higher exposure levels. The proposed methodology has the advantage of allowing for latency functions that vary by exposure levels and, conversely, exposure-response relationships that are influenced by the latency structure. PMID:18613262

  4. Farmworker Children’s Residential Non-Dietary Exposure Estimates from Micro-Level Activity Time Series

    PubMed Central

    BEAMER, PALOMA I.; CANALES, ROBERT A.; BRADMAN, ASA; LECKIE, JAMES O.

    2009-01-01

    Farmworkers’ children may have increased pesticide exposure through dermal absorption and non-dietary ingestion, routes that are difficult to measure and model. The Cumulative Aggregate Simulation of Exposure (CASE) model, integrates the complexity of human behavior and variability of exposure processes by combining micro-level activity time series (MLATS) and mechanistic exposure equations. CASE was used to estimate residential non-dietary organophosphate pesticide exposure (i.e., inhalation, dermal, and non-dietary ingestion) to California farmworker children and evaluate the micro-activity approach. MLATS collected from children and distributions developed from pesticide measurements in farmworkers’ residences served as inputs. While estimated diazinon exposure was greater for inhalation, chlorpyrifos exposure was greater for the other routes. Greater variability existed between children (?B2=0.22?0.39) than within each child’s simulations (?W2=0.01?0.02) for dermal and non-dietary ingestion. Dermal exposure simulations were not significantly different than measured values from dosimeters worn by the children. Non-dietary ingestion exposure estimates were comparable to duplicate diet measurements, indicating this route may contribute substantially to aggregate exposure. The results suggest the importance of the micro-activity approach for estimating non-dietary exposure. Other methods may underestimate exposure via these routes. Model simulations can be used to identify at-risk children and target intervention strategies. PMID:19744713

  5. Visualisation of blood and lymphatic vessels with increasing exposure time of the detector

    SciTech Connect

    Kalchenko, V V; Kuznetsov, Yu L; Meglinski, I V

    2013-07-31

    We describe the laser speckle contrast method for simultaneous noninvasive imaging of blood and lymphatic vessels of living organisms, based on increasing detector exposure time. In contrast to standard methods of fluorescent angiography, this technique of vascular bed imaging and lymphatic and blood vessel demarcation does not employ toxic fluorescent markers. The method is particularly promising with respect to the physiology of the cardiovascular system under in vivo conditions. (laser applications in biology and medicine)

  6. Effect of methodology, dilution, and exposure time on the tuberculocidal activity of glutaraldehyde-based disinfectants.

    PubMed Central

    Cole, E C; Rutala, W A; Nessen, L; Wannamaker, N S; Weber, D J

    1990-01-01

    The Association of Official Analytical Chemists (AOAC) test for assessing the tuberculocidal activity of disinfectants has been shown to be variable. A modified AOAC test, which substituted Middlebrook 7H9 broth as the primary subculture medium and used neutralization by dilution, was compared with the standard AOAC method to assess the mycobactericidal activity of three glutaraldehyde-based disinfectants at 20 degrees C and various exposure times. These changes had a marked effect on results, with the modified AOAC test providing more positive penicylinders per 10 replicates in 12 of the 13 comparisons that provided positive results. These differences were observed with both Mycobacterium bovis (ATCC 35743) and a clinical isolate of Mycobacterium tuberculosis. The effects of various exposure times to and dilutions of the glutaraldehyde-based disinfectants were also examined. The minimum exposure time needed to inactivate reliably M. bovis or M. tuberculosis with 2% glutaraldehyde was 20 min at 20 degrees C. Diluting 2% glutaraldehyde caused a significant decline in mycobactericidal activity. Modification of the standard AOAC test to improve its sensitivity in detecting the failure of disinfectants to inactivate mycobacteria is indicated. PMID:2116760

  7. Microgravity Inhibits Resting T Cell Immunity in an Exposure Time-Dependent Manner

    PubMed Central

    Luo, Haiying; Wang, Chongzhen; Feng, Meifu; Zhao, Yong

    2014-01-01

    Background: Decline immune function is well documented after spaceflights. Microgravity is one of the key factors directly suppressing the function of immune system. Though T cell immune response was inhibited by microgravity, it is not clearly whether activation would be inhibited after a pre-exposure of microgravity on T lymphocytes at the resting state. Methods: We herein investigated the response ability of resting CD4+ and CD8+ T cells experiencing pre-exposure of modeled microgravity (MMg) for 0, 8, 16 and 24 hrs to concanavalin A (ConA) stimulation. The phenotypes and subsets of immune cells were determined by flow cytometry. Results: Both CD4+ and CD8+ T cells with an MMg pre-exposure exhibited decreased expressions of activation-markers including CD25, CD69 and CD71, inflammatory cytokine secretion and cell proliferation in response to ConA compared with T cells with 1g controls in an MMg exposure time- dependent manner. Moreover, short term MMg treatment caused more severe decreased proliferation in CD4+ T cells than in CD8+ T cells. Conclusions: MMg can directly impact on resting T cell subsets. CD4+ T cells were more sensitive to the microgravity inhibition than CD8+ T cells in respect of cell proliferation. These results offered new insights for the MMg-caused T cell functional defects. PMID:24396290

  8. Time allocation shifts and pollutant exposure due to traffic congestion: An analysis using the national human activity pattern survey

    Microsoft Academic Search

    Kai Zhang; Stuart A. Batterman

    2009-01-01

    Traffic congestion increases air pollutant exposures of commuters and urban populations due to the increased time spent in traffic and the increased vehicular emissions that occur in congestion, especially “stop-and-go” traffic. Increased time in traffic also decreases time in other microenvironments, a trade-off that has not been considered in previous time activity pattern (TAP) analyses conducted for exposure assessment purposes.

  9. The design of a miniature personal exposure monitor for continuous real-time data acquisition in electromagnetic field exposure assessment

    Microsoft Academic Search

    N. H. Hansen; T. J. Conroy; B. W. Wilson

    1994-01-01

    The design of a small, light-weight personal exposure monitor suitable for use in EMF exposure assessment studies is nearing completion at Pacific Northwest Laboratory. The monitor is designed to be non-obtrusive, battery operated, and able to continuously record extremely low-frequency (ELF) (1Ohz--500hz) magnetic-field data. It also captures high-frequency (500hz--1OMhz) transients that exceed a preset threshold, retaining the largest transients in

  10. Quantifying the Effects of Chemical Heterogeneity by Combining Lagrangean Transport and the Exposure-time Concept

    NASA Astrophysics Data System (ADS)

    Seeboonruang, U.; Ginn, T. R.

    2001-12-01

    The fate of subsurface contaminants is often heavily dependent on both physical and chemical properties of an aquifer, e.g. hydraulic conductivity, aquifer boundary conditions, and the quantity and distribution of reactive zones. One way to represent the coupled effects of tranpsort and solid-phase chemical heterogeneity is via the cumulative reactivity, or the reaction time, endured by the solution as it undergoes transport through the aquifer. This reaction time is the total time that the solute has been exposed to reactive zones that in general are spatially distributed on multiple scales, and is itself a distributed quantity. The association between the physical and chemical properties and the groundwater velocity field is what gives rise to the distribution of cumulative reactivity, and it is possible to write a mass-balance equation governing the evolution of this distribution. A random walk particle tracking technique and the exposure time concept are combined here to solve this equation in the Lagrangean form. The solution characterizes the transport and reactions via a joint frequency distribution function between the travel time and exposure time of a passive tracer. This distribution is useful in scaling, or averaging, certain reactive transport phenomena in physically and chemically heterogeneous flow fields in the natural subsurface.

  11. Time-averaged copper concentrations from continuous exposures predicts pulsed exposure toxicity to the marine diatom, Phaeodactylum tricornutum: Importance of uptake and elimination.

    PubMed

    Angel, Brad M; Simpson, Stuart L; Chariton, Anthony A; Stauber, Jenny L; Jolley, Dianne F

    2015-07-01

    Intermittent, fluctuating and pulsed contaminant discharges result in organisms receiving highly variable contaminant exposures. Current water quality guidelines are predominantly derived using data from continuous exposure toxicity tests, and most frequently applied by regulators with the assumption that concentrations from a single sampling event will provide a meaningful approach to assessing potential effects. This study investigated the effect of single and multiple (daily) dissolved copper pulses on the marine diatom, Phaeodactylum tricornutum, including measurements of copper uptake and elimination to investigate the toxic mechanism. Copper pulses of between 0.5 and 24h and continuous exposures with equivalent 72-h time-averaged concentrations (TACs) resulted in similar biomass inhibition of P. tricornutum, with continuous exposures often being marginally more toxic. Rates of cell division generally recovered to control levels within 24h of the copper pulse removal. Upon resuspension in clean seawater, the extracellular copper per cell decreased rapidly, whereas the intracellular copper per cell decreased slowly. Negligible loss of copper from the total algal biomass indicated that P. tricornutum did not have an effective mechanism for eliminating copper from cells, rather the intracellular copper decreased as a result of dilution by cellular division as the algal growth rate recovered. The measurement of copper uptake after 72-h exposure and kinetics of elimination thereafter suggest that continuous exposures are marginally more toxic to P. tricornutum than pulsed copper exposures with equivalent TACs because slow internalization and saturation of algal membrane transport sites results in less copper uptake into pulse-exposed cells than continuously-exposed cells coupled with dilution of internalized copper via cellular division in the post-exposure period. In the case of P. tricornutum, the results indicate that water quality guidelines for copper based on continuous exposure will be conservative when applied to short-term discharges. PMID:25911575

  12. Increases in Retrospective Accounts of War-Zone Exposure Over Time: The Role of PTSD Symptom Severity

    Microsoft Academic Search

    Lizabeth Roeraer; Brett T. Litz; Susan M. Orsillo; Peter J. Ehlich; Matthew J. Friedman

    1998-01-01

    Retrospective reports of the frequency of war-zone exposure are commonly used as objective indices in studies investigating the mental health consequences of exposure to such stressors. To explore the temporal stability of these types of reports, we obtained frequency estimates of exposure to war-zone stressors at two time points from 460 U.S. soldiers who had served in the peace-keeping mission

  13. Exposure Nomographs

    NASA Astrophysics Data System (ADS)

    Zissell, Ronald E.

    Correct exposure times may be determined from nomographs relating signal-to-noise ratio, exposure time, color, seeing, and magnitude. The equations needed to construct the nomographs are developed. Calibration techniques are discussed.

  14. Influence of exposure time on the biotransformation rate of benzo(a)anthracene in fish

    SciTech Connect

    Maagd, P.G.J. de; Poorte, J. de; Sijm, D.T.H.M. [Utrecht Univ. (Netherlands); Opperhuizen, A. [NICM, The Hague (Netherlands)

    1995-12-31

    Biotransformation of PAH can yield in the formation of carcinogenic metabolites, therefore, determining the rate at which metabolites are formed is of importance to risk assessment. Biotransformation rates can be affected by inducing agents, hormonal status, temperature etc. To determine if biotransformation rates of PAH are influenced by auto-induction, juvenile fathead minnows were exposed to benzo(a)anthracene in water for various exposure times. After exposure for 5, 10, 24, 72, 168 or 336 hours no significant differences between biotransformation rates were found. The variation within each biotransformation rate was less than 20%. From these findings it is concluded that auto-induction by benzo(a)anthracene does not occur in fathead minnow.

  15. Demonstration of real-time monitoring of a photolithographic exposure process using chemical ionization mass spectrometry

    SciTech Connect

    Mowry, C.D. [Sandia National Labs., Albuquerque, NM (United States). Analytical Chemistry Dept.

    1998-02-01

    Silicon wafers are coated with photoresist and exposed to ultraviolet (UV) light in a laboratory to simulate typical conditions expected in an actual semiconductor manufacturing process tool. Air is drawn through the exposure chamber and analyzed using chemical ionization mass spectrometry (CI/MS). Species that evaporate or outgas from the wafer are thus detected. The purpose of such analyses is to determine the potential of CI/MS as a real-time process monitoring tool. Results demonstrate that CI/MS can remotely detect the products evolved before, during, and after wafer UV exposure; and that the quantity and type of products vary with the photoresist coated on the wafer. Such monitoring could provide semiconductor manufacturers benefits in quality control and process analysis. Tool and photoresist manufacturers could also realize benefits from this measurement technique with respect to new tool, method, or photoresist development. The benefits realized can lead to improved device yields and reduced product and development costs.

  16. Combined effects of exposure time and copper toxicity on the demography of Moina macrocopa (Crustacea: Cladocera).

    PubMed

    Gama-Flores, José Luis; Sarma, S S S; Nandini, S

    2009-01-01

    Cohort life table experiments were conducted on M. macrocopa using copper at three nominal concentrations (as CuSO(4), 0.1, 0.2 and 0.4 mg L(- 1), in addition to controls) for different periods of exposure (3 to 24 h). Age-specific survivorship of M. macrocopa decreased in relation to age of the cohort, concentration and duration of exposure to copper. Age-specific life expectancy curves also decreased with increasing age of the cohort. However, at low copper levels and shorter exposure time, there was an increase in life expectancy when the cohort was about 10 day old. Fecundity (m(x)) was nearly regular in controls; however, at higher copper levels and longer duration of exposure, the offspring production was more oscillating. The offspring production completely ceased when continuously exposed to CuSO(4) at 0.4 mg L(- 1). Most of the measured demography variables significantly decreased with increasing concentration of Cu in the medium. The average lifespan and life expectancy at birth varied 2.9 to 9.6 and 2.4 to 9.1 days, respectively. Gross reproductive rate (GRR) varied from 31 to 89 offspring female(- 1) lifespan(- 1), while the survival-weighted net reproductive rates were nearly one-third of the GRR. Generation time of M. macrocopa varied from 5 to 7 days while the rate of population increase ranged from 0.36 to 0.84 per day. The results are discussed in relation to the sensitivity of M. macrocopa to copper toxicity and the necessity of amending the national water quality criteria in Mexico. PMID:19089719

  17. Acute exposure to 2G phase shifts the rat circadian timing system

    NASA Technical Reports Server (NTRS)

    Hoban-Higgins, T. M.; Murakami, D. M.; Tandon, T.; Fuller, C. A.

    1995-01-01

    The circadian timing system (CTS) provides internal and external temporal coordination of an animal's physiology and behavior. In mammals, the generation and coordination of these circadian rhythms is controlled by a neural pacemaker, the suprachiasmatic nucleus (SCN), located within the hypothalamus. The pacemaker is synchronized to the 24 hour day by time cures (zeitgebers) such as the light/dark cycle. When an animal is exposed to an environment without time cues, the circadian rhythms maintain internal temporal coordination, but exhibit a 'free-running' condition in which the period length is determined by the internal pacemaker. Maintenance of internal and external temporal coordination are critical for normal physiological and psychological function in human and non-human primates. Exposure to altered gravitational environments has been shown to affect the amplitude, mean, and timing of circadian rhythms in species ranging from unicellular organisms to man. However, it has not been determined whether altered gravitational fields have a direct effect on the neural pacemaker, or affect peripheral parameters. In previous studies, the ability of a stimulus to phase shift circadian rhythms was used to determine whether a stimulus has a direct effect on the neural pacemaker. The present experiment was performed in order to determine whether acute exposure to a hyperdynamic field could phase shift circadian rhythms.

  18. REAL-TIME MODELING AND MEASUREMENT OF MOBILE SOURCE POLLUTANT CONCENTRATIONS FOR ESTIMATING HUMAN EXPOSURES IN COMMUNITIES NEAR ROADWAYS

    EPA Science Inventory

    The United States Environmental Protection Agency's (EPA) National Exposure Research Laboratory (NERL) is pursuing a project to improve the methodology for real-time site specific modeling of human exposure to pollutants from motor vehicles. The overall project goal is to deve...

  19. Application of alternative spatiotemporal metrics of ambient air pollution exposure in a time-series epidemiological study in Atlanta.

    PubMed

    Sarnat, Stefanie Ebelt; Sarnat, Jeremy A; Mulholland, James; Isakov, Vlad; Özkaynak, Halûk; Chang, Howard H; Klein, Mitchel; Tolbert, Paige E

    2013-01-01

    Exposure error in studies of ambient air pollution and health that use city-wide measures of exposure may be substantial for pollutants that exhibit spatiotemporal variability. Alternative spatiotemporal metrics of exposure for traffic-related and regional pollutants were applied in a time-series study of ambient air pollution and cardiorespiratory emergency department visits in Atlanta, GA, USA. Exposure metrics included daily central site monitoring for particles and gases; daily spatially refined ambient concentrations obtained from regional background monitors, local-scale dispersion, and hybrid air quality models; and spatially refined ambient exposures from population exposure models. Health risk estimates from Poisson models using the different exposure metrics were compared. We observed stronger associations, particularly for traffic-related pollutants, when using spatially refined ambient concentrations compared with a conventional central site exposure assignment approach. For some relationships, estimates of spatially refined ambient population exposures showed slightly stronger associations than corresponding spatially refined ambient concentrations. Using spatially refined pollutant metrics, we identified socioeconomic disparities in concentration-response functions that were not observed when using central site data. In some cases, spatially refined pollutant metrics identified associations with health that were not observed using measurements from the central site. Complexity and challenges in incorporating modeled pollutant estimates in time-series studies are discussed. PMID:23963512

  20. Consequences of ethanol exposure on cued and contextual fear conditioning and extinction in adulthood differ depending on timing of exposure

    PubMed Central

    Broadwater, Margaret; Spear, Linda P.

    2013-01-01

    Some evidence suggests that adolescents are more sensitive than adults to ethanol-induced cognitive deficits and that these effects may be long-lasting. The purpose of Exp 1 was to determine if early-mid adolescent [Postnatal day (P) 28-48] intermittent ethanol exposure would affect later learning and memory in a Pavlovian fear conditioning paradigm differently than comparable exposures in adulthood (P70-90). In Exp 2 animals were exposed to ethanol during mid-late adolescence (P35-55) to assess whether age of initiation within the adolescent period would influence learning and memory differentially. Male Sprague-Dawley rats were given 4 g/kg i.g. ethanol (25%) or water every 48 hours for a total of 11 exposures. After a 22 day non-ethanol period, animals were fear conditioned to a context (relatively hippocampal-dependent task) or tone (amygdala-dependent task), followed by retention tests and extinction (mPFC-dependent) of this conditioning. Despite similar acquisition, a deficit in context fear retention was evident in animals exposed to ethanol in early adolescence, an effect not observed after a comparable ethanol exposure in mid-late adolescence or adulthood. In contrast, animals that were exposed to ethanol in mid-late adolescence or adulthood showed enhanced resistance to context extinction. Together these findings suggest that repeated ethanol imparts long-lasting consequences on learning and memory, with outcomes that differ depending on age of exposure. These results may reflect differential influence of ethanol on the brain as it changes throughout ontogeny and may have implications for alcohol use not only throughout the developmental period of adolescence, but also in adulthood. PMID:23938333

  1. Self-reported exertion levels on time/activity diaries: application to exposure assessment

    SciTech Connect

    Schwab, M.; Terblanche, A.P.; Spengler, J.D. (Harvard School of Public Health, Department of Environmental Health, Boston, MA (United States))

    1991-07-01

    Recent developments in air pollution analysis have focused on methods for collecting data on contaminant levels in the locations actually frequented by people, especially personal monitoring. While there is still much to understand about human exposures, the next advancements will be in the area of dose assessment. This paper discusses the results of a study designed to provide data for linking exposure to dose. Specifically, we used time/activity diaries to collect information on the exertion levels associated with the reported activities. As part of a community health study, 91 children between the ages of 9 and 11 kept diaries over a two-week summer-time period (July 1989) and during a two-week school-time period (September 1989). The diary was also administered for two days to 42 teenagers between the ages of 15 and 17. This paper describes our concerns about interpreting self-reported exertion levels, particularly with respect to the disparity between participant and researcher perception and coding. We then present the distribution of exertion levels associated with children's activities, highlighting seasonal, day-of-week, and age-group differences.

  2. Non parametric denoising methods based on wavelets: Application to electron microscopy images in low exposure time

    NASA Astrophysics Data System (ADS)

    Soumia, Sid Ahmed; Messali, Zoubeida; Ouahabi, Abdeldjalil; Trepout, Sylvain; Messaoudi, Cedric; Marco, Sergio

    2015-01-01

    The 3D reconstruction of the Cryo-Transmission Electron Microscopy (Cryo-TEM) and Energy Filtering TEM images (EFTEM) hampered by the noisy nature of these images, so that their alignment becomes so difficult. This noise refers to the collision between the frozen hydrated biological samples and the electrons beam, where the specimen is exposed to the radiation with a high exposure time. This sensitivity to the electrons beam led specialists to obtain the specimen projection images at very low exposure time, which resulting the emergence of a new problem, an extremely low signal-to-noise ratio (SNR). This paper investigates the problem of TEM images denoising when they are acquired at very low exposure time. So, our main objective is to enhance the quality of TEM images to improve the alignment process which will in turn improve the three dimensional tomography reconstructions. We have done multiple tests on special TEM images acquired at different exposure time 0.5s, 0.2s, 0.1s and 1s (i.e. with different values of SNR)) and equipped by Golding beads for helping us in the assessment step. We herein, propose a structure to combine multiple noisy copies of the TEM images. The structure is based on four different denoising methods, to combine the multiple noisy TEM images copies. Namely, the four different methods are Soft, the Hard as Wavelet-Thresholding methods, Bilateral Filter as a non-linear technique able to maintain the edges neatly, and the Bayesian approach in the wavelet domain, in which context modeling is used to estimate the parameter for each coefficient. To ensure getting a high signal-to-noise ratio, we have guaranteed that we are using the appropriate wavelet family at the appropriate level. So we have chosen â?IJsym8â?? wavelet at level 3 as the most appropriate parameter. Whereas, for the bilateral filtering many tests are done in order to determine the proper filter parameters represented by the size of the filter, the range parameter and the spatial parameter respectively. The experiments reported in this paper demonstrate the performance of the Bilateral Filtering and the Bayesian approaches in terms of improving the SNRout and the image quality. Taken together, these results suggest that the Bayesian process has a potential to outperform all the used methods, where in the multiple noisy copies structure it gave us the best SNRout without change of the golden beads diameter. The Bayesian approach yielded enhanced average image without needing a huge amount of copies.

  3. Sociality and Sickness: Have Cytokines Evolved to Serve Social Functions beyond Times of Pathogen Exposure?

    PubMed Central

    Hennessy, Michael B.; Deak, Terrence; Schiml, Patricia A.

    2013-01-01

    During pathogen exposure or some forms of stress, proinflammatory processes induce an array of motivated and behavioral adjustments termed “sickness behaviors”. Although withdrawal from social interactions is a commonly observed sickness behavior, the relation between social behavior and sickness is much more complex. Sickness can suppress or stimulate social behavior. Sickness can serve as a social cue. Stressors that are social in nature can induce sickness behaviors, and sickness behavior can be readily suppressed by meaningful social stimuli. The nature, context, and timing of these effects together suggest that cytokine-induced behavior may play a role in mediating social interactions in various non-pathological conditions. PMID:24184399

  4. Validation of exposure time for discharge measurements made with two bottom-tracking acoustic doppler current profilers

    USGS Publications Warehouse

    Czuba, J.A.; Oberg, K.

    2008-01-01

    Previous work by Oberg and Mueller of the U.S. Geological Survey in 2007 concluded that exposure time (total time spent sampling the flow) is a critical factor in reducing measurement uncertainty. In a subsequent paper, Oberg and Mueller validated these conclusions using one set of data to show that the effect of exposure time on the uncertainty of the measured discharge is independent of stream width, depth, and range of boat speeds. Analysis of eight StreamPro acoustic Doppler current profiler (ADCP) measurements indicate that they fall within and show a similar trend to the Rio Grande ADCP data previously reported. Four special validation measurements were made for the purpose of verifying the conclusions of Oberg and Mueller regarding exposure time for Rio Grande and StreamPro ADCPs. Analysis of these measurements confirms that exposure time is a critical factor in reducing measurement uncertainty and is independent of stream width, depth, and range of boat speeds. Furthermore, it appears that the relation between measured discharge uncertainty and exposure time is similar for both Rio Grande and StreamPro ADCPs. These results are applicable to ADCPs that make use of broadband technology using bottom-tracking to obtain the boat velocity. Based on this work, a minimum of two transects should be collected with an exposure time for all transects greater than or equal to 720 seconds in order to achieve an uncertainty of ??5 percent when using bottom-tracking ADCPs. ?? 2008 IEEE.

  5. GPS-based Microenvironment Tracker (MicroTrac) Model to Estimate Time-Location of Individuals for Air Pollution Exposure Assessments: Model Evaluation in Central North Carolina

    EPA Science Inventory

    A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure...

  6. Can time-weighted average concentrations be used to assess the risks of metsulfuron-methyl to Myriophyllum spicatum under different time-variable exposure regimes?

    PubMed

    Belgers, J D M; Aalderink, G H; Arts, G H P; Brock, T C M

    2011-10-01

    We tested the effects of the herbicide metsulfuron-methyl on growth of the submerged macrophyte Myriophyllum spicatum under laboratory conditions using different exposure scenarios. The exposures of each scenario were comparable in the concentration × time factor, viz., the same 21-d time-weighted average (TWA) concentrations but variable in peak exposure concentrations (ranging from 0.1 to 21000 ng ai L?¹) and exposure periods (1, 3, 7, 14 or 21 d). To study recovery potential of the exposed M. spicatum plants we continued the observation on shoot and root growth for another 21 d in herbicide-free medium so that the total observation period was 42 d. Non-destructive endpoints, length and number of new shoots and roots, were determined weekly from day 14 onwards. Destructive endpoints, dry-weight (DW) of main shoots, new shoots and new roots, were measured at the end of the experiment (t=42 d). Metsulfuron-methyl exposure in particular inhibited new tissue formation but was not lethal to main shoots. On days 21 and 42 after start exposure, EC??/EC?? values for new tissues expressed in terms of peak concentration (=measured concentration during exposure periods of different length) showed large differences between exposure scenarios in contrast to EC??/EC?? values for days 21 and 42 expressed in terms of 21-d and 42-d TWA concentrations, respectively. At the end of the experiment (day 42), 42-d TWA EC(x) values were remarkably similar between exposure scenarios, while a similar trend could already be observed on day 21 for 21-d TWA EC(x) values. For the macrophyte M. spicatum and exposure to the herbicide metsulfuron-methyl the TWA approach seems to be appropriate to use in the risk assessment. However, the data from the toxicity experiment suggest that on day 21 also the absolute height of the pulse exposure played a (minor) role in the exposure - response relationships observed. PMID:21875741

  7. Real-Time In Vivo Imaging of Retinal Cell Apoptosis after Laser Exposure

    PubMed Central

    Schmitz-Valckenberg, Steffen; Guo, Li; Maass, Annelie; Cheung, William; Vugler, Anthony; Moss, Stephen E.; Munro, Peter M. G.; Fitzke, Frederick W.; Cordeiro, M. Francesca

    2008-01-01

    Purpose To investigate whether the detection of apoptosing retinal cells (DARC) could detect cells undergoing apoptosis in a laser model of retinal damage. Methods Laser lesions were placed, with the use of a frequency-doubled Nd:YAG laser, on the retina in 34 eyes of anesthetized Dark Agouti rats. Lesion size and laser-induced retinal elevation were analyzed using in vivo reflectance imaging. Development of retinal cell apoptosis was assessed using intravitreal fluorescence-labeled annexin 5 in vivo with DARC technology from baseline until 90 minutes after laser application. Histologic analysis of retinal flat mounts and cross-sections was performed. Results The lateral and anteroposterior depth extension of the zone of laser damage was significantly larger for higher exposure settings. A strong diffuse signal, concentrated at the outer retina, was seen with DARC for low exposures (<300 ms and <300 mW). In comparison, higher exposures (>300 ms and >300 mW) resulted in detectable hyperfluorescent spots, mainly at the level of the inner retinal layers. Dose-dependent effects on spot density and positive correlation of spot density between lesion size (P < 0.0001) and retinal elevation (P < 0.0001) were demonstrated. Histology confirmed the presence of apoptosing retinal cells in the inner nuclear and the ganglion cell layers. Conclusions This is the first time that DARC has been used to determine apoptotic effects in the inner nuclear layer. The ability to monitor changes spatially and temporally in vivo promises to be a major advance in the real-time assessment of retinal diseases and treatment effects. PMID:18281610

  8. Dose, exposure time, and resolution in Serial X-ray Crystallography

    SciTech Connect

    Starodub, D; Rez, P; Hembree, G; Howells, M; Shapiro, D; Chapman, H N; Fromme, P; Schmidt, K; Weierstall, U; Doak, R B; Spence, J C

    2007-03-22

    Using detailed simulation and analytical models, the exposure time is estimated for serial crystallography, where hydrated laser-aligned proteins are sprayed across a continuous synchrotron beam. The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed Serial Crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available fluxes of molecules and X-rays. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction of a density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate the number of proteins needed within the beam at any instant for a given resolution and X-ray flux. We confirm an inverse fourth power dependence of exposure time on resolution, with important implications for all coherent X-ray imaging. We find that multiple single-file protein beams will be needed for sub-nanometer resolution on current third generation synchrotrons, but not on fourth generation designs, where reconstruction of secondary protein structure at a resolution of 7 {angstrom} should be possible with short (below 100 s) exposures.

  9. Fabrication of long-period fiber gratings using low-pressure mercury lamp: Shortening of exposure time

    NASA Astrophysics Data System (ADS)

    Mizunami, Toru; Fujiyoshi, Tsubasa

    2014-08-01

    Long-period fiber gratings were fabricated by exposure to a low-pressure mercury lamp instead of using a laser or a fine positioning system. A hydrogen-loaded Ge-B-codoped fiber was used. Shortening of the exposure time was studied by increasing the grating length. For a grating period of 212 µm, a maximum loss of 20 dB was obtained with a grating length of 30 mm for an exposure time of 12 h. This time was 2/3 that in the case of a grating length of 20 mm. Shortening of the exposure time to 2/3 was also achieved with the grating period of 460 µm, and a 10 dB loss was obtained by exposure for 4.5 h. Fabrication after the outdiffusion of hydrogen was also studied. With a hydrogen concentration of 2/3 of the above experiments, the exposure time increased 1.5 times, and the resonance wavelengths were shorter than those with higher hydrogen concentrations. The growth rate of the refractive index modulation was 4.3 × 10-5/h peak to peak for a grating period of 212 µm. Temperature and strain sensitivities were also measured. Both the temperature and strain sensitivities of a grating period of 212 µm were higher than those of a grating period of 460 µm.

  10. Prolonged exposure to glare and driving time: effects on performance in a driving simulator.

    PubMed

    Ranney, T A; Simmons, L A; Masalonis, A J

    1999-11-01

    Twelve experienced truck drivers drove a fixed-base driving simulator for two 8 h sessions, including: (1) no glare and (2) intermittent glare presented in the exterior rear-view mirrors to simulate headlights from following vehicles. The driving task combined vehicle control on straight and curved road segments with detection of pedestrians appearing alongside the road and targets appearing in the rear-view mirrors. The results provided no evidence to support the hypothesis that prolonged exposure to glare impairs driving performance. However, we found time-related changes in target-detection and critical tracking performance, some of which were consistent with established patterns of diurnal variation. Subjective sleepiness ratings also increased over time. The results were interpreted within a model according to which drivers are able to maintain effective performance at early levels of impairment, thus compensating for increasing feelings of subjective tiredness. PMID:10487334

  11. Solar Ion Processing of Itokawa Grains: Constraints on Surface Exposure Times

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Keller, L. P.

    2015-01-01

    Analytical TEM observations obtained to date reveal that a significant sub-population of grains returned from the surface of asteroid Itokawa have had their outer 30-100 nm processed by space weathering effects. Although the effects include some surface deposition of condensed impact vapor and isolated impact melt splashes, much of the width of the space weathered outer margins or "rims" on grains is derived from solar wind processing of the original host grain. Similar to what has long been reported for some lunar grains, the ion-processed rims on Itokawa grains exhibit varing degrees and depths of penetration of atomic-displacement ion damage, resulting in complete amorphization for some rims (particularly in plagioclase), or formation of highly defective but still crystalline structures in others (particularly in pyroxene and olivine). Possibly different from lunar grains, however, is the presence of isolated internal cavities or voids in Itokawa grain rims, which may be implantation "bubbles" due to accumulating implanted solar wind H and/or He. For a given mineral exposed at a particular set of long term solar wind conditions, the level of ion damage in a given grain rim, the depth of damage penetration represented by the rim width, and the formation or lack of formation of implantation bubbles can all be linked to the time spent by the grain in an uncovered state on the topmost, space-exposed, regolith surface. For the lunar case, we have previously shown that with reasonable assumptions about solar wind characteristics over time, a model can be developed to estimate this exposure time based on the width of amorphous rims on lunar grains. Here we report on an expansion of the model to cover exposure time information contained in the array of solar ion-induced features in Itokawa grains.

  12. Controlling silver nanoparticle exposure in algal toxicity testing – A matter of timing

    PubMed Central

    Baun, Anders

    2015-01-01

    The aquatic ecotoxicity testing of nanoparticles is complicated by unstable exposure conditions resulting from various transformation processes of nanoparticles in aqueous suspensions. In this study, we investigated the influence of exposure timing on the algal test response to silver nanoparticles (AgNPs), by reducing the incubation time and by aging the AgNPs in algal medium prior to testing. The freshwater green algae Pseudokirchneriella subcapitata were exposed to AgNO3, NM-300?K (a representative AgNP) and citrate stabilized AgNPs from two different manufacturers (AgNP1 and AgNP2) in a standard algal growth inhibition test (ISO 8692:2004) for 48?h and a short-term (2?h) 14C-assimilation test. For AgNO3, similar responses were obtained in the two tests, whereas freshly prepared suspensions of citrate stabilized AgNPs were less toxic in the 2-h tests compared to the 48-h tests. The 2-h test was found applicable for dissolved silver, but yielded non-monotonous concentration–response relationships and poor reproducibility for freshly prepared AgNP suspensions. However, when aging AgNPs in algal medium 24?h prior to testing, clear concentration–response patterns emerged and reproducibility increased. Prolonged aging to 48?h increased toxicity in the 2-h tests whereas aging beyond 48?h reduced toxicity. Our results demonstrate that the outcome of algal toxicity testing of AgNPs is highly influenced not only by the test duration, but also by the time passed from the moment AgNPs are added to the test medium. This time-dependency should be considered when nanomaterial dispersion protocols for ecotoxicity testing are developed. PMID:24842597

  13. Exposure Pathways

    MedlinePLUS

    ... to decay, the exposure continues. For radionuclides that decay slowly, the exposure continues over a very long time. Inhalation is of most concern for radionuclides that are alpha or beta particle emitters. Alpha and beta particles can transfer ...

  14. Estimating the Time Interval Between Exposure to the World Trade Center Disaster and Incident Diagnoses of Obstructive Airway Disease

    PubMed Central

    Glaser, Michelle S.; Webber, Mayris P.; Zeig-Owens, Rachel; Weakley, Jessica; Liu, Xiaoxue; Ye, Fen; Cohen, Hillel W.; Aldrich, Thomas K.; Kelly, Kerry J.; Nolan, Anna; Weiden, Michael D.; Prezant, David J.; Hall, Charles B.

    2014-01-01

    Respiratory disorders are associated with occupational and environmental exposures. The latency period between exposure and disease onset remains uncertain. The World Trade Center (WTC) disaster presents a unique opportunity to describe the latency period for obstructive airway disease (OAD) diagnoses. This prospective cohort study of New York City firefighters compared the timing and incidence of physician-diagnosed OAD relative to WTC exposure. Exposure was categorized by WTC arrival time as high (on the morning of September 11, 2001), moderate (after noon on September 11, 2001, or on September 12, 2001), or low (during September 13–24, 2001). We modeled relative rates and 95% confidence intervals of OAD incidence by exposure over the first 5 years after September 11, 2001, estimating the times of change in the relative rate with change point models. We observed a change point at 15 months after September 11, 2001. Before 15 months, the relative rate for the high- versus low-exposure group was 3.96 (95% confidence interval: 2.51, 6.26) and thereafter, it was 1.76 (95% confidence interval: 1.26, 2.46). Incident OAD was associated with WTC exposure for at least 5 years after September 11, 2001. There were higher rates of new-onset OAD among the high-exposure group during the first 15 months and, to a lesser extent, throughout follow-up. This difference in relative rate by exposure occurred despite full and free access to health care for all WTC-exposed firefighters, demonstrating the persistence of WTC-associated OAD risk. PMID:24980522

  15. Reconciling Scratch Space Consumption, Exposure, and Volatility to Achieve Timely Staging of Job Input Data

    SciTech Connect

    Monti, Henri [Virginia Polytechnic Institute and State University (Virginia Tech); Butt, Ali R [Virginia Polytechnic Institute and State University (Virginia Tech); Vazhkudai, Sudharshan S [ORNL

    2010-04-01

    Innovative scientific applications and emerging dense data sources are creating a data deluge for high-end computing systems. Processing such large input data typically involves copying (or staging) onto the supercomputer's specialized high-speed storage, scratch space, for sustained high I/O throughput. The current practice of conservatively staging data as early as possible makes the data vulnerable to storage failures, which may entail re-staging and consequently reduced job throughput. To address this, we present a timely staging framework that uses a combination of job startup time predictions, user-specified intermediate nodes, and decentralized data delivery to coincide input data staging with job start-up. By delaying staging to when it is necessary, the exposure to failures and its effects can be reduced. Evaluation using both PlanetLab and simulations based on three years of Jaguar (No. 1 in Top500) job logs show as much as 85.9% reduction in staging times compared to direct transfers, 75.2% reduction in wait time on scratch, and 2.4% reduction in usage/hour.

  16. Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

    DOE PAGESBeta

    Lambe, A. T.; Chhabra, P. S.; Onasch, T. B.; Brune, W. H.; Hunter, J. F.; Kroll, J. H.; Cummings, M. J.; Brogan, J. F.; Parmar, Y.; Worsnop, D. R.; et al

    2015-01-01

    We performed a systematic intercomparison study of the chemistry and yields of secondary organic aerosol (SOA) generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0 × 108 to 2.2 × 1010 molec cm?3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 106 to 2 × 107 molec cm?3 over exposure times of several hours. The OH concentration in themore »chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. In most cases, for a specific SOA type the most-oxidized chamber SOA and the least-oxidized flow reactor SOA have similar mass spectra, oxygen-to-carbon and hydrogen-to-carbon ratios, and carbon oxidation states at integrated OH exposures between approximately 1 × 1011 and 2 × 1011 molec cm?3 s, or about 1–2 days of equivalent atmospheric oxidation. This observation suggests that in the range of available OH exposure overlap for the flow reactor and chambers, SOA elemental composition as measured by an aerosol mass spectrometer is similar whether the precursor is exposed to low OH concentrations over long exposure times or high OH concentrations over short exposure times. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of sulfate seed particles on isoprene SOA yield measurements was examined in the flow reactor. The studies show that seed particles increase the yield of SOA produced in flow reactors by a factor of 3 to 5 and may also account in part for higher SOA yields obtained in the chambers, where seed particles are routinely used.« less

  17. A decision support system for real-time stress detection during virtual reality exposure.

    PubMed

    Gaggioli, Andrea; Cipresso, Pietro; Serino, Silvia; Pioggia, Giovanni; Tartarisco, Gennaro; Baldus, Giovanni; Corda, Daniele; Ferro, Marcello; Carbonaro, Nicola; Tognetti, Alessandro; De Rossi, Danilo; Giakoumis, Dimitris; Tzovaras, Dimitrios; Riera, Alejandro; Riva, Giuseppe

    2014-01-01

    Virtual Reality (VR) is increasingly being used in combination with psycho-physiological measures to improve assessment of distress in mental health research and therapy. However, the analysis and interpretation of multiple physiological measures is time consuming and requires specific skills, which are not available to most clinicians. To address this issue, we designed and developed a Decision Support System (DSS) for automatic classification of stress levels during exposure to VR environments. The DSS integrates different biosensor data (ECG, breathing rate, EEG) and behavioral data (body gestures correlated with stress), following a training process in which self-rated and clinical-rated stress levels are used as ground truth. Detected stress events for each VR session are reported to the therapist as an aggregated value (ranging from 0 to 1) and graphically displayed on a diagram accessible by the therapist through a web-based interface. PMID:24732491

  18. Ear swelling test by using laser speckle imaging with a long exposure time

    NASA Astrophysics Data System (ADS)

    Kalchenko, Vyacheslav; Kuznetsov, Yuri; Preise, Dina; Meglinski, Igor; Harmelin, Alon

    2014-06-01

    Laser speckle imaging with long exposure time has been applied noninvasively to visualize the immediate reaction of cutaneous vessels in mice in response to a known primary irritant and potential allergen-methyl salicylate. The compound has been used topically on the surface of the pinna and the reaction of the vascular network was examined. We demonstrate that irritant-induced acute vascular reaction can be effectively and accurately detected by laser speckle imaging technique. The current approach holds a great promise for application in routine screening of the cutaneous vascular response induced by contact agents, screenings of mouse ear swelling test, and testing the allergenic potential of new synthetic materials and healthcare pharmaceutical products.

  19. Ear swelling test by using laser speckle imaging with a long exposure time.

    PubMed

    Kalchenko, Vyacheslav; Kuznetsov, Yuri; Preise, Dina; Meglinski, Igor; Harmelin, Alon

    2014-06-01

    Laser speckle imaging with long exposure time has been applied noninvasively to visualize the immediate reaction of cutaneous vessels in mice in response to a known primary irritant and potential allergen—methyl salicylate. The compound has been used topically on the surface of the pinna and the reaction of the vascular network was examined. We demonstrate that irritant-induced acute vascular reaction can be effectively and accurately detected by laser speckle imaging technique. The current approach holds a great promise for application in routine screening of the cutaneous vascular response induced by contact agents, screenings of mouse ear swelling test, and testing the allergenic potential of new synthetic materials and healthcare pharmaceutical products. PMID:24967913

  20. Assessment of Two Portable Real-Time Particle Monitors Used in Nanomaterial Workplace Exposure Evaluations

    PubMed Central

    Liu, Yuewei; Beaucham, Catherine C.; Pearce, Terri A.; Zhuang, Ziqing

    2014-01-01

    Background Nanoparticle emission assessment technique was developed to semi-quantitatively evaluate nanomaterial exposures and employs a combination of filter based samples and portable real-time particle monitors, including a condensation particle counter (CPC) and an optical particle counter (OPC), to detect nanomaterial releases. This laboratory study evaluated the results from CPC and OPC simultaneously measuring a polydisperse aerosol to assess their variability and accuracy. Methods and Results Two CPCs and two OPCs were used to evaluate a polydisperse sodium chloride aerosol within an enclosed chamber. The measurement results for number concentration versus time were compared between paired particle monitors of the same type, and to results from the Scanning Mobility Particle Spectrometer (SMPS) which was widely used to measure concentration of size-specific particles. According to analyses by using the Bland-Altman method, the CPCs displayed a constant mean percent difference of ?3.8% (95% agreement limits: ?9.1 to 1.6%; range of 95% agreement limit: 10.7%) with the chamber particle concentration below its dynamic upper limit (100,000 particles per cubic centimeter). The mean percent difference increased from ?3.4% to ?12.0% (range of 95% agreement limits: 7.1%) with increasing particle concentrations that were above the dynamic upper limit. The OPC results showed the percent difference within 15% for measurements in particles with size ranges of 300 to 500 and 500 to 1000 regardless of the particle concentration. Compared with SMPS measurements, the CPC gave a mean percent difference of 22.9% (95% agreement limits: 10.5% to 35.2%); whereas the measurements from OPC were not comparable. Conclusions This study demonstrated that CPC and OPC are useful for measuring nanoparticle exposures but the results from an individual monitor should be interpreted based upon the instrument's technical parameters. Future research should challenge these monitors with particles of different sizes, shapes, or composition, to determine measurement comparability and accuracy across various workplace nanomaterials. PMID:25148239

  1. Association of Established Smoking Among Adolescents With Timing of Exposure to Smoking Depicted in Movies

    PubMed Central

    Longacre, Meghan R.; Beach, Michael L.; Adachi-Mejia, Anna M.; Titus, Linda J.; Dalton, Madeline A.

    2012-01-01

    Background It is not known whether exposure to smoking depicted in movies carries greater influence during early or late adolescence. We aimed to quantify the independent relative contribution to established smoking of exposure to smoking depicted in movies during both early and late adolescence. Methods We prospectively assessed 2049 nonsmoking students recruited from 14 randomly selected public schools in New Hampshire and Vermont. At baseline enrollment, students aged 10–14 years completed a written survey to determine personal, family, and sociodemographic characteristics and exposure to depictions of smoking in the movies (early exposure). Seven years later, we conducted follow-up telephone interviews to ascertain follow-up exposure to movie smoking (late exposure) and smoking behavior. We used multiple regression models to assess associations between early and late exposure and development of established smoking. Results One-sixth (17.3%) of the sample progressed to established smoking. In analyses that controlled for covariates and included early and late exposure in the same model, we found that students in the highest quartile for early exposure had 73% greater risk of established smoking than those in the lowest quartile for early exposure (27.8% vs 8.6%; relative risk for Q4 vs Q1 = 1.73, 95% confidence interval = 1.14 to 2.62). However, late exposure to depictions of smoking in movies was not statistically significantly associated with established smoking (22.1% vs 14.0%; relative risk for Q4 vs Q1 = 1.13, 95% confidence interval = 0.89 to 1.44). Whereas 31.6% of established smoking was attributable to early exposure, only an additional 5.3% was attributable to late exposure. Conclusions Early exposure to smoking depicted in movies is associated with established smoking among adolescents. Educational and policy-related interventions should focus on minimizing early exposure to smoking depicted in movies. PMID:22423010

  2. Vascular and nerve damage in workers exposed to vibrating tools. The importance of objective measurements of exposure time.

    PubMed

    Gerhardsson, Lars; Balogh, Istvan; Hambert, Per-Arne; Hjortsberg, Ulf; Karlsson, Jan-Erik

    2005-01-01

    The aim of the present study was to compare the development of vibration white fingers (VWF) in workers in relation to different ways of exposure estimation, and their relationship to the standard ISO 5349, annex A. Nineteen vibration exposed (grinding machines) male workers completed a questionnaire followed by a structured interview including questions regarding their estimated hand-held vibration exposure. Neurophysiological tests such as fractionated nerve conduction velocity in hands and arms, vibrotactile perception thresholds and temperature thresholds were determined. The subjective estimation of the mean daily exposure-time to vibrating tools was 192 min (range 18-480 min) among the workers. The estimated mean exposure time calculated from the consumption of grinding wheels was 42 min (range 18-60 min), approximately a four-fold overestimation (Wilcoxon's signed ranks test, p<0.001). Thus, objective measurements of the exposure time, related to the standard ISO 5349, which in this case were based on the consumption of grinding wheels, will in most cases give a better basis for adequate risk assessment than self-exposure assessment. PMID:15627422

  3. Quantification of Acute Vocal Fold Epithelial Surface Damage with Increasing Time and Magnitude Doses of Vibration Exposure

    PubMed Central

    Kojima, Tsuyoshi; Van Deusen, Mark; Jerome, W. Gray; Garrett, C. Gaelyn; Sivasankar, M. Preeti; Novaleski, Carolyn K.; Rousseau, Bernard

    2014-01-01

    Because the vocal folds undergo repeated trauma during continuous cycles of vibration, the epithelium is routinely susceptible to damage during phonation. Excessive and prolonged vibration exposure is considered a significant predisposing factor in the development of vocal fold pathology. The purpose of the present study was to quantify the extent of epithelial surface damage following increased time and magnitude doses of vibration exposure using an in vivo rabbit phonation model. Forty-five New Zealand white breeder rabbits were randomized to nine groups and received varying phonation time-doses (30, 60, or 120 minutes) and magnitude-doses (control, modal intensity phonation, or raised intensity phonation) of vibration exposure. Scanning electron microscopy and transmission electron microscopy was used to quantify the degree of epithelial surface damage. Results revealed a significant reduction in microprojection density, microprojection height, and depth of the epithelial surface with increasing time and phonation magnitudes doses, signifying increased epithelial surface damage risk with excessive and prolonged vibration exposure. Destruction to the epithelial cell surface may provide significant insight into the disruption of cell function following prolonged vibration exposure. One important goal achieved in the present study was the quantification of epithelial surface damage using objective imaging criteria. These data provide an important foundation for future studies of long-term tissue recovery from excessive and prolonged vibration exposure. PMID:24626217

  4. Constraining the Timing of Neoglaciation: Moraine Exposure Ages from Baffin Island, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Crump, S. E.; Miller, G. H.

    2014-12-01

    A long-term Neoglacial cooling trend, beginning ~6 ka, is well documented across the Arctic and correlates with a monotonic decline in Northern Hemisphere summer insolation. However, paleoclimate proxy records point to decadal- to millennial-scale variability superimposed on overall cooling. This climate variability is reflected in the fluctuations of Arctic glaciers over the course of several millennia. The most recent Neoglacial advance, the Little Ice Age (LIA; ~1275-1850 AD), was generally more extensive than pre-LIA advances and thus destroyed most evidence of previous advances. As such, the timing and extent of earlier Neoglacial advances are not well constrained. However, several extant glaciers on Cumberland Peninsula, Baffin Island, are fronted by nested ice-cored moraine sequences in which multiple pre-LIA moraines are preserved. We have generated absolute ages on moraine sequences for Snow Creek and Throne Glaciers using 10Be in moraine boulders. Nine 10Be ages from the two most distal moraine crests at Snow Creek Glacier range from ~1.8 ka to ~5.7 ka, and twelve ages from the two most distal moraine crests at Throne Glacier range from ~1.1 ka to ~4.6 ka. The wide spread of exposure ages in these settings is likely due to the degradation of moraine ice cores and the disturbance of older moraines by younger readvances. Because these processes result in the exposure of new clasts on the moraine post-emplacement, the oldest ages in these datasets likely provide the best estimates for the earliest Neoglacial advances. These data also indicate that in some settings, early Neoglacial alpine glacier advances reached similar extents as their LIA maxima, possibly due to large ice-cored moraines impeding LIA advances. Glacier modeling efforts and complementary lacustrine sediment records will help to unravel the complex Neoglacial history in this region.

  5. Numeral size, spacing between targets, and exposure time in discrimination by elderly people using an lcd monitor.

    PubMed

    Huang, Kuo-Chen; Yeh, Po-Chan

    2007-04-01

    The present study investigated the effects of numeral size, spacing between targets, and exposure time on the discrimination performance by elderly and younger people using a liquid crystal display screen. Analysis showed size of numerals significantly affected discrimination, which increased with increasing numeral size. Spacing between targets also had a significant effect on discrimination, i.e., the larger the space between numerals, the better their discrimination. When the spacing between numerals increased to 4 or 5 points, however, discrimination did not increase beyond that for 3-point spacing. Although performance increased with increasing exposure time, the difference in discrimination at an exposure time of 0.8 vs 1.0 sec. was not significant. The accuracy by the elderly group was less than that by younger subjects. PMID:17566444

  6. Optimal combination of number of participants and number of repeated measurements in longitudinal studies with time-varying exposure.

    PubMed

    Barrera-Gómez, Jose; Spiegelman, Donna; Basagaña, Xavier

    2013-11-30

    In the context of observational longitudinal studies, we explored the values of the number of participants and the number of repeated measurements that maximize the power to detect the hypothesized effect, given the total cost of the study. We considered two different models, one that assumes a transient effect of exposure and one that assumes a cumulative effect. Results were derived for a continuous response variable, whose covariance structure was assumed to be damped exponential, and a binary time-varying exposure. Under certain assumptions, we derived simple formulas for the approximate solution to the problem in the particular case in which the response covariance structure is assumed to be compound symmetry. Results showed the importance of the exposure intraclass correlation in determining the optimal combination of the number of participants and the number of repeated measurements, and therefore the optimized power. Thus, incorrectly assuming a time-invariant exposure leads to inefficient designs. We also analyzed the sensitivity of results to dropout, mis-specification of the response correlation structure, allowing a time-varying exposure prevalence and potential confounding impact. We illustrated some of these results in a real study. In addition, we provide software to perform all the calculations required to explore the combination of the number of participants and the number of repeated measurements. PMID:23740818

  7. Environmental and occupational exposures to PAH in the Czech Republic: Personal exposure monitoring coupled with HPLC/time-programmed fluorescence detection

    SciTech Connect

    Williams, R.W.; Hattaway, K.E. [Integrated Lab. Systems, Research Triangle Park, NC (United States); Watts, R.R.; Lewtas, J. [Environmental Protection Agency, Research Triangle Park, NC (United States)

    1994-12-31

    The US Environmental Protection Agency has collaborated with health researchers in the Czech Republic to determine polynuclear aromatic hydrocarbon (PAH) exposures for populations in highly polluted environments and in various occupations. These investigations used personal exposure monitors (PEMs) that were developed to allow separate and simultaneous collection of fine particles, vapor phase nicotine and vapor phase organics. Samples were extracted and analyzed for 16 priority PAHs by optimized HPLC coupled with time-programmed fluorescence detection. Nicotine analysis was performed using capillary gas chromatography with nitrogen-phosphorus detection. Personal exposure monitoring periods of up to 24 continuous hours were conducted for: (1) Teplice and Prachatice policemen, who spent a major portion of their day outdoors; (2) open-pit coal miners; (3) health researchers working in a laboratory; and (4) coke oven workers. Total particle-bound PAHs ranged from 1.5 {micro}g/m{sup 3} for the health researchers to 52 {micro}g/m{sup 3} for the topside coke oven workers. Vapor phase PAH concentrations also varied greatly depending on occupation and ranged from 0.6 {micro}g/m{sup 3} for city policemen to 261 {micro}g/m{sup 3} for the coke oven workers. Carcinogenic PAHs, which were predominantly found associated with particular matter (> 90%), typically included benzo(a)anthracene, chrysene, and benzo(a)pyrene.

  8. Predicting personal exposure to airborne carbonyls using residential measurements and time/activity data

    NASA Astrophysics Data System (ADS)

    Liu, Weili; Zhang, Junfeng (Jim); Korn, Leo R.; Zhang, Lin; Weisel, Clifford P.; Turpin, Barbara; Morandi, Maria; Stock, Tom; Colome, Steve

    As a part of the Relationships of Indoor, Outdoor, and Personal Air (RIOPA) study, 48 h integrated residential indoor, outdoor, and personal exposure concentrations of 10 carbonyls were simultaneously measured in 234 homes selected from three US cities using the Passive Aldehydes and Ketones Samplers (PAKS). In this paper, we examine the feasibility of using residential indoor concentrations to predict personal exposures to carbonyls. Based on paired t-tests, the means of indoor concentrations were not different from those of personal exposure concentrations for eight out of the 10 measured carbonyls, indicating indoor carbonyls concentrations, in general, well predicted the central tendency of personal exposure concentrations. In a linear regression model, indoor concentrations explained 47%, 55%, and 65% of personal exposure variance for formaldehyde, acetaldehyde, and hexaldehyde, respectively. The predictability of indoor concentrations on cross-individual variability in personal exposure for the other carbonyls was poorer, explaining<20% of variance for acetone, acrolein, crotonaldehyde, and glyoxal. A factor analysis, coupled with multiple linear regression analyses, was also performed to examine the impact of human activities on personal exposure concentrations. It was found that activities related to driving a vehicle and performing yard work had significant impacts on personal exposures to a few carbonyls.

  9. Application of MOSFET detectors for dosimetry in small animal radiography using short exposure times.

    PubMed

    De Lin, Ming; Toncheva, Greta; Nguyen, Giao; Kim, Sangroh; Anderson-Evans, Colin; Johnson, G Allan; Yoshizumi, Terry T

    2008-08-01

    Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies. PMID:18666818

  10. Application of MOSFET Detectors for Dosimetry in Small Animal Radiography Using Short Exposure Times

    PubMed Central

    De Lin, Ming; Toncheva, Greta; Nguyen, Giao; Kim, Sangroh; Anderson-Evans, Colin; Johnson, G. Allan; Yoshizumi, Terry T.

    2008-01-01

    Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies. PMID:18666818

  11. Performance of a 512 x 512 gated CMOS imager with a 250 ps exposure time

    NASA Astrophysics Data System (ADS)

    Teruya, Alan T.; Vernon, Stephen P.; Moody, James D.; Hsing, Warren W.; Brown, Christopher G.; Griffin, Matthew; Mead, Andrew S.; Tran, Vu

    2012-10-01

    We describe the performance of a 512x512 gated CMOS read out integrated circuit (ROIC) with a 250 ps exposure time. A low-skew, H-tree trigger distribution system is used to locally generate individual pixel gates in each 8x8 neighborhood of the ROIC. The temporal width of the gate is voltage controlled and user selectable via a precision potentiometer. The gating implementation was first validated in optical tests of a 64x64 pixel prototype ROIC developed as a proof-of-concept during the early phases of the development program. The layout of the H-Tree addresses each quadrant of the ROIC independently and admits operation of the ROIC in two modes. If "common mode" triggering is used, the camera provides a single 512x512 image. If independent triggers are used, the camera can provide up to four 256x256 images with a frame separation set by the trigger intervals. The ROIC design includes small (sub-pixel) optical photodiode structures to allow test and characterization of the ROIC using optical sources prior to bump bonding. Reported test results were obtained using short pulse, second harmonic Ti:Sapphire laser systems operating at ?~ 400 nm at sub-ps pulse widths.

  12. Performance of a 512 x 512 Gated CMOS Imager with a 250 ps Exposure Time

    SciTech Connect

    Teruya, A T; Moody, J D; Hsing, W W; Brown, C G; Griffin, M; Mead, A S

    2012-10-01

    We describe the performance of a 512x512 gated CMOS read out integrated circuit (ROIC) with a 250 ps exposure time. A low-skew, H-tree trigger distribution system is used to locally generate individual pixel gates in each 8x8 neighborhood of the ROIC. The temporal width of the gate is voltage controlled and user selectable via a precision potentiometer. The gating implementation was first validated in optical tests of a 64x64 pixel prototype ROIC developed as a proof-of-concept during the early phases of the development program. The layout of the H-Tree addresses each quadrant of the ROIC independently and admits operation of the ROIC in two modes. If “common mode” triggering is used, the camera provides a single 512x512 image. If independent triggers are used, the camera can provide up to four 256x256 images with a frame separation set by the trigger intervals. The ROIC design includes small (sub-pixel) optical photodiode structures to allow test and characterization of the ROIC using optical sources prior to bump bonding. Reported test results were obtained using short pulse, second harmonic Ti:Sapphire laser systems operating at ?~ 400 nm at sub-ps pulse widths.

  13. Time course of lung retention and toxicity of inhaled particles: short-term exposure to nano-Ceria.

    PubMed

    Keller, Jana; Wohlleben, Wendel; Ma-Hock, Lan; Strauss, Volker; Gröters, Sibylle; Küttler, Karin; Wiench, Karin; Herden, Christiane; Oberdörster, Günter; van Ravenzwaay, Bennard; Landsiedel, Robert

    2014-11-01

    Two Ceria nanomaterials (NM-211 and NM-212) were tested for inhalation toxicity and organ burdens in order to design a chronic and carcinogenicity inhalation study (OECD TG No. 453). Rats inhaled aerosol concentrations of 0.5, 5, and 25 mg/m(3) by whole-body exposure for 6 h/day on 5 consecutive days for 1 or 4 weeks with a post-exposure period of 24 or 129 days, respectively. Lungs were examined by bronchoalveolar lavage and histopathology. Inhaled Ceria is deposited in the lung and cleared with a half-time of 40 days; at aerosol concentrations higher than 0.5 mg/m(3), this clearance was impaired resulting in a half-time above 200 days (25 mg/m(3)). After 5 days, Ceria (>0.5 mg/m(3)) induced an early inflammatory reaction by increases of neutrophils in the lung which decreased with time, with sustained exposure, and also after the exposure was terminated (during the post-exposure period). The neutrophil number observed in bronchoalveolar lavage fluid (BALF) was decreasing and supplemented by mononuclear cells, especially macrophages which were visible in histopathology but not in BALF. Further progression to granulomatous inflammation was observed 4 weeks post-exposure. The surface area of the particles provided a dose metrics with the best correlation of the two Ceria's inflammatory responses; hence, the inflammation appears to be directed by the particle surface rather than mass or volume in the lung. Observing the time course of lung burden and inflammation, it appears that the dose rate of particle deposition drove an initial inflammatory reaction by neutrophils. The later phase (after 4 weeks) was dominated by mononuclear cells, especially macrophages. The progression toward the subsequent granulomatous reaction was driven by the duration and amount of the particles in the lung. The further progression of the biological response will be determined in the ongoing long-term study. PMID:25273020

  14. Resilience and recovery: the effect of triclosan exposure timing during development, on the structure and function of river biofilm communities.

    PubMed

    Lawrence, J R; Topp, E; Waiser, M J; Tumber, V; Roy, J; Swerhone, G D W; Leavitt, P; Paule, A; Korber, D R

    2015-04-01

    Triclosan (TCS) is a ubiquitous antibacterial agent found in soaps, scrubs, and consumer products. There is limited information on hazardous effects of TCS in the environment. Here, rotating annular reactors were used to cultivate river biofilm communities exposed to 1.8 ?g l(-1) TCS with the timing and duration of exposure and recovery during development varied. Two major treatment regimens were employed: (i) biofilm development for 2, 4 or 6 weeks prior to TCS exposure and (ii) exposure of biofilms to TCS for 2, 4 or 6 weeks followed by recovery. Biofilms not exposed to TCS were used as a reference condition. Communities cultivated without and then exposed to TCS all exhibited reductions in algal biomass and significant (p<0.05) reductions in cyanobacterial biomass. No significant effects were observed on bacterial biomass. CLSM imaging of biofilms at 8 weeks revealed unique endpoints in terms of community architecture. Community composition was altered by any exposure to TCS, as indicated by significant shifts in denaturing gradient gel electrophoresis fingerprints and exopolymer composition relative to the reference. Bacterial, algal and cyanobacterial components initially exposed to TCS were significantly different from those TCS-free at time zero. Pigment analyses suggested that significant changes in composition of algal and cyanobacterial populations occurred with TCS exposure. Bacterial thymidine incorporation rates were reduced by TCS exposure and carbon utilization spectra shifted in terms substrate metabolism. Direct counts of protozoans indicated that TCS was suppressive, whereas micrometazoan populations were, in some instances, stimulated. These results indicate that even a relatively brief exposure of a river biofilm community to relatively low levels of TCS alters both the trajectory and final community structure. Although some evidence of recovery was observed, removal of TCS did not result in a return to the unexposed reference condition. PMID:25731684

  15. TIME-DEPENDENT EFFECTS ON GENE EXPRESSION IN RAT SEMINAL VESICLE DEVELOPMENTALLY ALTERED BY IN UTERO EXPOSURE TO TCDD

    EPA Science Inventory

    TIME-DEPENDENT EFFECTS ON GENE EXPRESSION IN RAT SEMINAL VESICLE DEVELOPMENTALLY ALTERED BY IN UTERO EXPOSURE TO TCDD. V M Richardson', J T Hamm2, and L S Birnbaum1. 'USEPA, ORD/NHEERL/ETD, Research Triangle Park, NC, USA, 'Curriculum in Toxicology, University of North Carolina, ...

  16. The Timing of Prenatal Exposure to Maternal Cortisol and Psychosocial Stress Is Associated with Human Infant Cognitive Development

    ERIC Educational Resources Information Center

    Davis, Elysia P.; Sandman, Curt A.

    2010-01-01

    The consequences of prenatal maternal stress for development were examined in 125 full-term infants at 3, 6, and 12 months of age. Maternal cortisol and psychological state were evaluated 5 times during pregnancy. Exposure to elevated concentrations of cortisol early in gestation was associated with a slower rate of development over the 1st year…

  17. War exposure, 5-HTTPLPR genotype and life-time risk of depression. Sylvaine Artero1,2

    E-print Network

    Paris-Sud XI, Université de

    .91 [1.44- 5.88]) but did not reach significance in subjects who were older at the time of the event (p=0 transporter gene (5-HTT). In children 4 , adolescents 5,6 and young adults 7-12 it has been observed depression and suicidal ideation after exposure to stress than individuals with one or two long (L) alleles

  18. Mouse pulmonary dose- and time course-responses induced by exposure to multi-walled carbon nanotubes

    Microsoft Academic Search

    Dale W. Porter; Ann F. Hubbs; Robert R. Mercer; Nianqiang Wu; Michael G. Wolfarth; Krishnan Sriram; Stephen Leonard; Lori Battelli; Diane Schwegler-Berry; Sherry Friend; Michael Andrew; Bean T. Chen; Shuji Tsuruoka; Morinobu Endo; Vincent Castranova

    2010-01-01

    Carbon nanotubes (CNT) come in a variety of types, but one of the most common forms is multi-walled carbon nanotubes (MWCNT). MWCNT have potential applications in many diverse commercial processes, and thus human exposures are considered to be likely. In order to investigate the pulmonary toxicity of MWCNT, we conducted an in vivo dose-response and time course study of MWCNT

  19. Diesel engine exhaust and lung cancer mortality: time-related factors in exposure and risk.

    PubMed

    Moolgavkar, Suresh H; Chang, Ellen T; Luebeck, Georg; Lau, Edmund C; Watson, Heather N; Crump, Kenny S; Boffetta, Paolo; McClellan, Roger

    2015-04-01

    To develop a quantitative exposure-response relationship between concentrations and durations of inhaled diesel engine exhaust (DEE) and increases in lung cancer risks, we examined the role of temporal factors in modifying the estimated effects of exposure to DEE on lung cancer mortality and characterized risk by mine type in the Diesel Exhaust in Miners Study (DEMS) cohort, which followed 12,315 workers through December 1997. We analyzed the data using parametric functions based on concepts of multistage carcinogenesis to directly estimate the hazard functions associated with estimated exposure to a surrogate marker of DEE, respirable elemental carbon (REC). The REC-associated risk of lung cancer mortality in DEMS is driven by increased risk in only one of four mine types (limestone), with statistically significant heterogeneity by mine type and no significant exposure-response relationship after removal of the limestone mine workers. Temporal factors, such as duration of exposure, play an important role in determining the risk of lung cancer mortality following exposure to REC, and the relative risk declines after exposure to REC stops. There is evidence of effect modification of risk by attained age. The modifying impact of temporal factors and effect modification by age should be addressed in any quantitative risk assessment (QRA) of DEE. Until there is a better understanding of why the risk appears to be confined to a single mine type, data from DEMS cannot reliably be used for QRA. PMID:25683254

  20. The fly that came in from the cold: geographic variation of recovery time from low-temperature exposure in Drosophila subobscura

    Microsoft Academic Search

    J. R. David; P. Gibert; B. Moreteau; G. W. Gilchrist; R. B. Huey

    2003-01-01

    Summary 1. The time required for an ectotherm to recover from cold exposure is a useful, non- lethal index of cold tolerance. We explore how recovery times are affected by exposure to low temperatures, develop statistical methodologies, and study geographic variation in recovery time in four populations of Drosophila subobscura , a cold-tolerant species. 2. We exposed flies to a

  1. Estrogens in the wrong place at the wrong time: Fetal BPA exposure and mammary cancer.

    PubMed

    Paulose, Tessie; Speroni, Lucia; Sonnenschein, Carlos; Soto, Ana M

    2015-07-01

    Iatrogenic gestational exposure to diethylstilbestrol (DES) induced alterations of the genital tract and predisposed individuals to develop clear cell carcinoma of the vagina as well as breast cancer later in life. Gestational exposure of rodents to a related compound, the xenoestrogen bisphenol-A (BPA) increases the propensity to develop mammary cancer during adulthood, long after cessation of exposure. Exposure to BPA during gestation induces morphological alterations in both the stroma and the epithelium of the fetal mammary gland at 18 days of age. We postulate that the primary target of BPA is the fetal stroma, the only mammary tissue expressing estrogen receptors during fetal life. BPA would then alter the reciprocal stroma-epithelial interactions that mediate mammogenesis. In addition to this direct effect on the mammary gland, BPA is postulated to affect the hypothalamus and thus in turn affect the regulation of mammotropic hormones at puberty and beyond. PMID:25277313

  2. Assessing the effects of exposure timing on biomarker expression using 17beta-estradiol

    EPA Science Inventory

    Temporal and spatial variability in estrogenicity has been documented for many treated wastewater effluents with the consequences of this variability on the expression of biomarkers of endocrine disruption being largely unknown. Laboratory exposure studies usually utilize constan...

  3. Comparison of four mobility particle sizers with different time resolution for stationary exposure measurements

    Microsoft Academic Search

    Christof Asbach; Heinz Kaminski; Heinz Fissan; Christian Monz; Dirk Dahmann; Sonja Mülhopt; Hanns R. Paur; Heinz J. Kiesling; Friedhelm Herrmann; Matthias Voetz; Thomas A. J. Kuhlbusch

    2009-01-01

    Exposure to airborne ultrafine and nanoparticles has raised increased interest over the recent years as they may cause adverse\\u000a health effects. A common way to quantify exposure to airborne particles is to measure particle number size distributions through\\u000a electrical mobility analysis. Four mobility particle sizers have been subject to a detailed intercomparison study, a TSI Fast\\u000a Mobility Particle Sizer (FMPS),

  4. Non-linear increase of vitamin D content in eggs from chicks treated with increasing exposure times of ultraviolet light.

    PubMed

    Kühn, Julia; Schutkowski, Alexandra; Hirche, Frank; Baur, Anja C; Mielenz, Norbert; Stangl, Gabriele I

    2015-04-01

    Vitamin D fortified food can help to reduce the prevalence for vitamin D deficiency. Previous data provided evidence that eggs from hens exposed to ultraviolet (UV) light contain large quantities of vitamin D. In the current study, we assessed the efficacy of vitamin D enrichment in eggs upon increasing daily UVB exposure times. We further addressed the question whether extended UVB irradiation affects the skin content of 7-dehydrocholesterol. To this end, 35 hens were assigned to 7 groups of 5 animals each and were exposed to UVB light (76?W/cm(2)) for 0, 15, 30, 60, 120, 180 and 300min per day, respectively. Eggs from the treatment groups were collected at baseline and after 2, 3 and 4 weeks of treatment, respectively. Skin samples were gained at the end of 4 weeks. Vitamin D metabolites were quantified by liquid chromatography-tandem mass spectrometry. The contents of vitamin D3 and 25(OH)D3 in egg yolk raised non-linear in response to increasing daily UVB exposure times. The vitamin D3 content did not reach a clear-cut plateau within the chosen UVB treatment times. A daily UVB exposure time of 300min resulted in vitamin D3 contents of 28.6?g/100g egg yolk dry matter. In contrast to vitamin D3, the 25(OH)D3 content in the egg yolk achieved a maximum upon an UVB irradiation time of 60min/d. The cutaneous 7-dehydrocholesterol contents were not altered in response to the chosen UVB irradiation times. In conclusion, the data show a distinct non-linear dose-response relationship of UVB exposure times on the total vitamin D content in eggs. This article is part of a special issue entitled '17th Vitamin D Workshop'. PMID:25445915

  5. Motoneuron axon pathfinding errors in zebrafish: differential effects related to concentration and timing of nicotine exposure.

    PubMed

    Menelaou, Evdokia; Paul, Latoya T; Perera, Surangi N; Svoboda, Kurt R

    2015-04-01

    Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15-30 ?M). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. PMID:25668718

  6. Clutch morphology and the timing of exposure impact the susceptibility of aquatic insect eggs to esfenvalerate.

    PubMed

    Palmquist, Katherine R; Jenkins, Jeffrey J; Jepson, Paul C

    2008-08-01

    We investigated Baetis spp. (mayfly), Hesperoperla pacifica (stonefly), and Brachycentrus americanus (caddisfly) susceptibility at the egg stage to esfenvalerate, a synthetic pyrethroid insecticide. Eggs were obtained from the field or from field-collected gravid females at sites near Corvallis (OR, USA) and the Metolius River at Camp Sherman (OR, USA) for static exposures under controlled conditions for temperature and light. Eggs were exposed to esfenvalerate for 48 h at concentrations ranging from 0.025 to 4.0 microg/L. No effect on mortality or posthatch growth was detected in H. pacifica eggs exposed to esfenvalerate concentrations up to 1.0 microg/L. Exposure to 0.07 microg/L of esfenvalerate, however, caused a significant increase in Baetis spp. egg mortality, and exposure of near-eclosion eggs to lower concentrations (0.025 and 0.05 microg/L) resulted in behavioral effects and reduced survivorship in newly hatched Baetis nymphs. Early stage B. americanus eggs were 10-fold more sensitive to esfenvalerate when removed from the gelatinous clutch before exposure, an indication that the gelatin affords protection from toxicant exposure. Exposures of near-hatch B. americanus clutches to esfenvalerate concentrations ranging between 0.035 and 0.2 microg/L, however, resulted in significant clutch death within clutches resulting from behavioral aberrations of first-instar larvae. The results of the present study suggest that aquatic insect egg clutch morphology can be a strong influence on susceptibility of embryos to esfenvalerate exposure. PMID:18616380

  7. Toxicogenomic studies of the rat brain at an early time point following acute sarin exposure.

    PubMed

    Damodaran, Tirupapuliyur V; Greenfield, Stephen T; Patel, Anand G; Dressman, Holly K; Lin, Siomon K; Abou-Donia, Mohamed B

    2006-03-01

    We have studied sarin-induced global gene expression patterns at an early time point (2 h: 0.5 x LD50) using Affymetrix Rat Neurobiology U34 chips and male Sprague-Dawley rats. A total of 46 genes showed statistically significant alterations from control levels. Three gene categories contained more of the altered genes than any other groups: ion channel (8 genes) and calcium channel and binding proteins (6 genes). Alterations were also found in the following gene groups: ATPases and ATP-based transporters (4), growth factors (4), G-protein-coupled receptor pathway-related molecules (3), neurotransmission and neurotransmitter transporters (3), cytoskeletal and cell adhesion molecules (2), hormones (2), mitochondria-associated proteins (2), myelin proteins (2), stress-activated molecules (2), cytokine (1), caspase (1), GABAnergic (1), glutamergic (1), immediate early gene (1), prostaglandin (1), transcription factor (1), and tyrosine phosphorylation molecule (1). Persistent alteration of the following genes also were noted: Arrb1, CaMKIIa, CaMKIId, Clcn5, IL-10, c-Kit, and Plp1, suggesting altered GPCR, kinase, channel, and cytokine pathways. Selected genes from the microarray data were further validated using relative RT-PCR. Some of those genes (GFAP, NF-H, CaMKIIa, Calm, and MBP) have been shown by other laboratories and ours, to be involved in the pathogenesis of sarin-induced pathology and organophosphate-induced delayed neurotoxicity (OPIDN). Induction of both proapoptotic (Bcl2l11, Casp6) and antiapoptotic (Bcl-X) genes, besides suppression of p21, suggest complex cell death/protection-related mechanisms operating early on. Principal component analysis (PCA) of the expression data confirmed that the changes in gene expression are a function of sarin exposure, since the control and treatment groups separated clearly. Our model (based on current and previous studies) indicates that both degenerative and regenerative pathways are activated early and contribute to the level of neurodegeneration at a later time, leading to neuro-pathological alterations. PMID:16733813

  8. Survival time analysis of least killifish (Heterandria formosa) and mosquitofish (Gambusia affinis) in acute exposures to endosulfan sulfate.

    PubMed

    Carriger, John F; Hoang, Tham C; Rand, Gary M

    2010-05-01

    Single-species flow-through toxicity tests were conducted to determine the times-to-death of two indigenous fish to South Florida--least killifish (Heterandria formosa) and mosquitofish (Gambusia affinis)--from acute exposure to endosulfan sulfate. Mortalities were recorded within 8-h periods from test initiation to termination at 96 h. The 96-h LC(50)s for least killifish and mosquitofish estimated using the trimmed-Spearman-Karber method were 2.0 and 2.3 microg/l, respectively. An accelerated failure time model was used to estimate times to death at selected concentrations. Data were fit to log-normal, log-logistic, and Weibull distributions. Acute toxicity data fit to the Weibull distribution produced a better relative fit than log-normal or log-logistic distributions for both toxicity tests. The survival-time profiles and associated statistics illustrate the benefit of considering exposure duration as well as concentration when predicting acute risk to species' populations. Both toxicity tests had similar outcomes from exposure to endosulfan sulfate, with least killifish being slightly more likely to die at lower concentrations and shorter time periods than mosquitofish. From the models generated by the toxicity tests, times-to-death for least killifish and mosquitofish were estimated for environmentally relevant concentrations of total endosulfan at a site of concern in South Florida. When the results from the current toxicity tests were compared to environmental concentrations from previous screening-level ecological risk assessments, the durations necessary to potentially kill 10% or more of the populations of the two native south Florida fish species were estimated to be 77 and 96 h for least killifish and mosquitofish, respectively. However, the exposure values included the alpha and beta isomers as well as endosulfan sulfate; therefore, an understanding of their toxicity might be important in understanding the survival dynamics of fish species in endosulfan sulfate-contaminated sites. PMID:19921326

  9. Risk factors for asthma and timing of exposure among first generation Arab immigrants: a pilot effort to elucidate the role of exposure to risk factors over multiple life stages

    EPA Science Inventory

    Considerable controversy exists over the role of aero-allergens in asthma etiology. Some studies show increased risk with microbe and allergen exposure, while others show decreased risk. These discrepancies may be explained by timing of exposure. Previous research suggests that e...

  10. 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 ?g m(-3) for BC with average values of 1.3 ± 2.2 ?g m(-3) (AM ± SD). Nitrogen dioxide exposure concentrations were in the range exposures (PEs) and central site (A) concentrations was evaluated, with only NO(2) exposures averaged over the sampling event significantly correlating with central site levels. The PE/A ratio ranged between 1.1 (BC) and 0.2-0.7 (NO(2)) in the absence of combustion sources to 13 (BC) for subjects commuting in trains and 2.9 (NO(2)) for subjects cooking with gas appliances. PMID:22513735

  11. Community Violence Exposure and Adolescents’ School Engagement and Academic Achievement Over Time

    PubMed Central

    Borofsky, Larissa A.; Kellerman, Ilana; Baucom, Brian; Oliver, Pamella H.; Margolin, Gayla

    2013-01-01

    Objective This study examined the relationships between community violence exposure and two related, but meaningfully distinct, academic outcomes: school engagement and academic achievement (GPA). Psychological symptoms were investigated as mediators of these relationships. Method One hundred eighteen youth reported on community violence exposure and school engagement twice during adolescence, and both parents and adolescents reported on psychological symptoms. Cumulative GPA was also acquired from participants. A path model and hierarchical multiple regression analyses were used to assess these relationships longitudinally. Results Earlier community violence exposure inversely predicted later school engagement, but earlier school engagement did not predict later community violence exposure. School engagement mediated the association between community violence exposure and school GPA. Internalizing and externalizing symptoms, but not posttraumatic stress symptoms, mediated the association between community violence and school engagement. Conclusions When adolescents are exposed to community violence, they may become vulnerable to a cascade of events including psychological symptoms and decreased connectedness to school, which ultimately can lead to overall poor academic achievement. The more proximal, changeable experiences of school connectedness and psychological symptoms offer targets for interventions offsetting long-term adverse academic consequences in violence-exposed youth. PMID:24163782

  12. Effect of cadmium level and exposure time on the competition between zooplankton species Moina macrocopa (Cladocera) and Brachionus calyciflorus (Rotifera).

    PubMed

    Gama-Flores, Jose Luis; Sarma, S S S; Nandini, S

    2006-01-01

    Competition among zooplankton is a natural phenomenon and often cladocerans are competitively superior to rotifers. However, anthropogenic factors including the release of industrial effluents, may influence this interaction. In this study, we evaluated the effect of cadmium (0.05 and 0.1 mg L(-1) as CdCl(2)) on competition between the cladoceran Moina macrocopa and the rotifer Brachionus calyciflorus. Since the release of industrial effluents is generally pulsed, we also exposed the test zooplankton species at different exposure periods (3, 6, 12 and 24 h) to the heavy metal. Regardless of exposure time and the presence of competing species, an increase in concentration of Cd resulted in decreased population growth of M. macrocopa and B. calyciflorus. Regardless of presence of the competing species and Cd concentration, an increase in exposure period resulted in decreased population growth rates of both the zooplankton species. In mixed cultures, in general, M. macrocopa outcompeted B. calyciflorus and completely eliminated it under conditions of high toxicant concentrations and longer exposure time. PMID:16760085

  13. Night-Time Decibel Hell: Mapping Noise Exposure Zones and Individual Annoyance Ratings in an Urban Environment in Ghana

    PubMed Central

    Zakpala, Rachel N.; Armah, Frederick Ato; Sackey, Brigid M.; Pabi, Opoku

    2014-01-01

    Although accumulating evidence over the past thirty years indicates that noise is an environmental stressor in residential settings, much of the data emanated from studies in high-intensity, noise impact zones around airports or major roads. Little is known about religious noise, especially at night, which is increasingly a growing concern for both the general public and policy-makers in sub-Saharan Africa. Using geographical information systems (GIS), this study measured and mapped exposure to religious noise in a rapidly urbanising municipality in Ghana. Quantitative noise risk assessment was used to evaluate the risk of religious noise-induced hearing loss to residents in the exposed neighbourhoods. The results show that all neighbourhoods where churches were situated had at least one location with significant risk of noise-induced hearing loss. However, there was no statistically significant relationship between neighbourhoods where religious noise exposure was the highest and where noise annoyance was the highest. The magnitude of the noise values for night-time exposure is remarkable particularly given that excessive night-time noise exposure has the greatest detrimental effect on public health. There is the need to focus on vulnerable groups, sensitive hours of the night, and possible confounding with air pollution in order to wholly address this potential hazard. PMID:25136476

  14. German health-related environmental monitoring: assessing time trends of the general population's exposure to heavy metals.

    PubMed

    Becker, K; Schroeter-Kermani, C; Seiwert, M; Rüther, M; Conrad, A; Schulz, C; Wilhelm, M; Wittsiepe, J; Günsel, A; Dobler, L; Kolossa-Gehring, M

    2013-06-01

    The German system of a health-related environmental monitoring is based upon two instruments: The German Environmental Survey (GerES) and the Environmental Specimen Bank (ESB). The ESB is a tool to describe time trends of human exposure. Each year approx. 500 students from 4 sampling locations are analysed for their heavy metal contents in blood, blood plasma, and urine. GerES is a nationwide representative cross-sectional study that has been conducted four times up to now. Both instruments have been used to measure heavy metals over the last decades and thus provide complementary information. Both instruments are useful to describe time trends. However, combining the two has an added value, which is demonstrated for heavy metals for the first time in this paper. Major results and the changing importance of sources of exposure to heavy metals (Pb, Cd, Hg, Au, Pt, U and Ni) are shown. This leads to the following conclusion about the today's relevance of exposure in Germany. For the study participants of the city of Muenster, lead in whole blood decreased from about 70 ?g/l in 1981 to levels below 15 ?g/l in 2009. GerES data of young adults confirmed this time trend and GerES IV on children revealed the decreasing relevance of lead in outdoor air and in drinking water. The concentrations of mercury in urine decreased because in Germany it is no longer recommended to use amalgam fillings for children. However, GerES IV and ESB data also demonstrate that despite the decline of these heavy metals exposures to nickel and uranium originating from drinking water are still of importance. PMID:23410801

  15. Stochastic modelling for biodosimetry: Predicting the chromosomal response to radiation at different time points after exposure

    NASA Astrophysics Data System (ADS)

    Deperas-Standylo, Joanna; Gudowska-Nowak, Ewa; Ritter, Sylvia

    2014-07-01

    Cytogenetic data accumulated from the experiments with peripheral blood lymphocytes exposed to densely ionizing radiation clearly demonstrate that for particles with linear energy transfer (LET) >100 keV/ ?m the derived relative biological effectiveness (RBE) will strongly depend on the time point chosen for the analysis. A reasonable prediction of radiation-induced chromosome damage and its distribution among cells can be achieved by exploiting Monte Carlo methodology along with the information about the radius of the penetrating ion-track and the LET of the ion beam. In order to examine the relationship between the track structure and the distribution of aberrations induced in human lymphocytes and to clarify the correlation between delays in the cell cycle progression and the aberration burden visible at the first post-irradiation mitosis, we have analyzed chromosome aberrations in lymphocytes exposed to Fe-ions with LET values of 335 keV/ ?m and formulated a Monte Carlo model which reflects time-delay in mitosis of aberrant cells. Within the model the frequency distributions of aberrations among cells follow the pattern of local energy distribution and are well approximated by a time-dependent compound Poisson statistics. The cell-division cycle of undamaged and aberrant cells and chromosome aberrations are modelled as a renewal process represented by a random sum of (independent and identically distributed) random elements S N = ? N i=0 X i . Here N stands for the number of particle traversals of cell nucleus, each leading to a statistically independent formation of X i aberrations. The parameter N is itself a random variable and reflects the cell cycle delay of heavily damaged cells. The probability distribution of S N follows a general law for which the moment generating function satisfies the relation ? S N = ? N ( ? X i ). Formulation of the Monte Carlo model which allows to predict expected fluxes of aberrant and non-aberrant cells has been based on several input information: (i) experimentally measured mitotic index in the population of irradiated cells; (ii) scored fraction of cells in first cell cycle; (iii) estimated average number of particle traversals per cell nucleus. By reconstructing the local dose distribution in the biological target, the relevant amount of lesions induced by ions is estimated from the biological effect induced by photons at the same dose level. Moreover, the total amount of aberrations induced within the entire population has been determined. For each subgroup of intact (non-hit) and aberrant cells the cell-division cycle has been analyzed reproducing correctly an expected correlation between mitotic delay and the number of aberrations carried by a cell. This observation is of particular importance for the proper estimation of the biological efficiency of ions and for the estimation of health risks associated with radiation exposure.

  16. The Toxic Exposure Surveillance System (TESS): Risk assessment and real-time toxicovigilance across United States poison centers

    SciTech Connect

    Watson, William A. [American Association of Poison Control Centers, 3201 New Mexico Ave NW, Suite 330, Washington, DC 20016 (United States); Litovitz, Toby L. [American Association of Poison Control Centers, 3201 New Mexico Ave NW, Suite 330, Washington, DC 20016 (United States)]. E-mail: toby@poison.org; Belson, Martin G. [National Center for Environmental Health/Agency for Toxic Substance and Disease Registry, Centers for Disease Control and Prevention, Atlanta, GA 30333 (United States); Funk Wolkin, Amy B. [National Center for Environmental Health/Agency for Toxic Substance and Disease Registry, Centers for Disease Control and Prevention, Atlanta, GA 30333 (United States); Patel, Manish [National Center for Environmental Health/Agency for Toxic Substance and Disease Registry, Centers for Disease Control and Prevention, Atlanta, GA 30333 (United States); Schier, Joshua G. [National Center for Environmental Health/Agency for Toxic Substance and Disease Registry, Centers for Disease Control and Prevention, Atlanta, GA 30333 (United States); Reid, Nicole E. [American Association of Poison Control Centers, 3201 New Mexico Ave NW, Suite 330, Washington, DC 20016 (United States); Kilbourne, Edwin [National Center for Environmental Health/Agency for Toxic Substance and Disease Registry, Centers for Disease Control and Prevention, Atlanta, GA 30333 (United States); Rubin, Carol [National Center for Environmental Health/Agency for Toxic Substance and Disease Registry, Centers for Disease Control and Prevention, Atlanta, GA 30333 (United States)

    2005-09-01

    The Toxic Exposure Surveillance System (TESS) is a uniform data set of US poison centers cases. Categories of information include the patient, the caller, the exposure, the substance(s), clinical toxicity, treatment, and medical outcome. The TESS database was initiated in 1985, and provides a baseline of more than 36.2 million cases through 2003. The database has been utilized for a number of safety evaluations. Consideration of the strengths and limitations of TESS data must be incorporated into data interpretation. Real-time toxicovigilance was initiated in 2003 with continuous uploading of new cases from all poison centers to a central database. Real-time toxicovigilance utilizing general and specific approaches is systematically run against TESS, further increasing the potential utility of poison center experiences as a means of early identification of potential public health threats.

  17. TIME COURSE OF METAL LOSS IN LUMBRICULUS VARIEGATUS FOLLOWING SEDIMENT EXPOSURES

    EPA Science Inventory

    After exposure for 21 d to sediment spiked with Cd, Pb, Cu, or Zn, oligochaetes held in clean water depurated metal rapidly over the first few hours, but much more slowly from 8 h up to 32 h. Results are consistent with previous work suggresting a 6-h depuration period as general...

  18. Do Time in Child Care and Peer Group Exposure Predict Poor Socioemotional Adjustment in Norway?

    ERIC Educational Resources Information Center

    Solheim, Elisabet; Wichstrøm, Lars; Belsky, Jay; Berg-Nielsen, Turid Suzanne

    2013-01-01

    Extensive exposure to nonparental child care during the first 4.5 years of life has been demonstrated in some American studies to negatively affect children's socioemotional functioning. Data from 935 preschool children who averaged 54.9 (SD = 3.0) months of age, from Trondheim, Norway were used to examine whether such negative effects, would…

  19. Time course of systemic oxidative stress and inflammatory response induced by an acute exposure to Residual Oil Fly Ash.

    PubMed

    Marchini, T; Magnani, N D; Paz, M L; Vanasco, V; Tasat, D; González Maglio, D H; Alvarez, S; Evelson, P A

    2014-01-15

    It is suggested that systemic oxidative stress and inflammation play a central role in the onset and progression of cardiovascular diseases associated with the exposure to particulate matter (PM). The aim of this work was to evaluate the time changes of systemic markers of oxidative stress and inflammation, after an acute exposure to Residual Oil Fly Ash (ROFA). Female Swiss mice were intranasally instilled with a ROFA suspension (1.0mg/kg body weight) or saline solution, and plasma levels of oxidative damage markers [thiobarbituric acid reactive substances (TBARSs) and protein carbonyls], antioxidant status [reduced (GSH) and oxidized (GSSG) glutathione, ascorbic acid levels, and superoxide dismutase (SOD) activity], cytokines levels, and intravascular leukocyte activation were evaluated after 1, 3 or 5h of exposure. Oxidative damage to lipids and decreased GSH/GSSG ratio were observed in ROFA-exposed mice as early as 1h. Afterwards, increased protein oxidation, decreased ascorbic acid content and SOD activity were found in this group at 3h. The onset of an adaptive response was observed at 5h after the ROFA exposure, as indicated by decreased TBARS plasma content and increased SOD activity. The observed increase in oxidative damage to plasma macromolecules, together with systemic antioxidants depletion, may be a consequence of a systemic inflammatory response triggered by the ROFA exposure, since increased TNF-? and IL-6 plasma levels and polymorphonuclear leukocytes activation was found at every evaluated time point. These findings contribute to the understanding of the increase in cardiovascular morbidity and mortality, in association with environmental PM inhalation. PMID:24321338

  20. Air exposure time of olive pastes during the extraction process and phenolic and volatile composition of virgin olive oil

    Microsoft Academic Search

    Maurizio Servili; Roberto Selvaggini; Agnese Taticchi; Sonia Esposto; Gianfrancesco Montedoro

    2003-01-01

    The time of exposure of olive pastes to air contact (TEOPAC) during malaxation was studied as a processing parameter that\\u000a could be used to control endogenous oxidoreductases, such as polyphenoloxidase, peroxidase, and lipoxygenase, which affect\\u000a virgin olive oil quality. Phenolic and volatile compounds were analyzed in the oils obtained using progressive TEOPAC at three\\u000a ripening stages of olives. Multivariate statistical

  1. Sensitivity and response time of three common Antarctic marine copepods to metal exposure.

    PubMed

    Zamora, Lara Marcus; King, Catherine K; Payne, Sarah J; Virtue, Patti

    2015-02-01

    Understanding the sensitivity of Antarctic marine organisms to metals is essential in order to manage environmental contamination risks. To date toxicity studies conducted on Antarctic marine species are limited. This study is the first to examine the acute effects of copper and cadmium on three common coastal Antarctic copepods: the calanoids Paralabidocera antarctica and Stephos longipes, and the cyclopoid Oncaea curvata. These copepods responded slowly to metal exposure (4-7d) emphasising that the exposure period of 48-96 h commonly used in toxicity tests with temperate and tropical species is not appropriate for polar organisms. We found that a longer 7 d exposure period was the minimum duration appropriate for Antarctic copepods. Although sensitivity to metal exposure varied between species, copper was more toxic than cadmium in all three species. P.antarctica was the most sensitive with 7d LC50 values for copper and cadmium of 20 ?g L(-1) and 237 ?g L(-1) respectively. Sensitivities to copper were similar for both O. curvata (LC50=64 ?g L(-1)) and S. longipes (LC50=56 ?g L(-1)), while O. curvata was more sensitive to cadmium (LC50=901 ?g L(-1)) than S. longipes (LC50=1250 ?g L(-1)). In comparison to copepods from lower latitudes, Antarctic copepods were more sensitive to copper and of similar sensitivity or less sensitive to cadmium. This study highlights the need for longer exposure periods in toxicity tests with slow responding Antarctic biota in order to generate relevant sensitivity data for inclusion in site-specific environmental quality guidelines for Antarctica. PMID:25128632

  2. Leisure time activities related to carcinogen exposure and lung cancer risk in never smokers. A case-control study.

    PubMed

    Ruano-Ravina, Alberto; García-Lavandeira, José Antonio; Torres-Durán, María; Prini-Guadalupe, Luciana; Parente-Lamelas, Isaura; Leiro-Fernández, Virginia; Montero-Martínez, Carmen; González-Barcala, Francisco Javier; Golpe-Gómez, Antonio; Martínez, Cristina; Castro-Añón, Olalla; Mejuto-Martí, María José; Barros-Dios, Juan Miguel

    2014-07-01

    We aim to assess the relationship between leisure time activities related to exposure to carcinogenic substances and lung cancer risk in a hospital-based case-control study performed in never smokers. We included never smoking cases with anatomopathologically confirmed lung cancer and never smoking controls undergoing trivial surgery, at 8 Spanish hospitals. The study was conducted between January 2011 and June 2013. Participants were older than 30 and had no previous neoplasms. All were personally interviewed focusing on lifestyle, environmental tobacco smoke exposure, occupational history and leisure time activities (including duration of such activities). Results were analyzed through logistic regression and adjusted also by residential radon and education level. We included 513 never smokers, 191 cases and 322 controls. The OR for those performing the studied leisure time activities was 1.43 (95%CI 0.78-2.61). When we restricted the analysis to those performing do-it-yourself activities for more than 10 years the OR was 2.21 (95%CI 0.93-5.27). Environmental tobacco smoke exposure did not modify this association. The effect for the different lung cancer histological types was very close to significance for adenocarcinoma but only when these activities were performed for more than 10 years. We encourage health professionals to recommend protective measures for those individuals while performing these hobbies to reduce the risk of lung cancer. PMID:24742725

  3. The effects of bisphenol A on emotional behavior depend upon the timing of exposure, age and gender in mice.

    PubMed

    Gioiosa, Laura; Parmigiani, Stefano; Vom Saal, Frederick S; Palanza, Paola

    2013-04-01

    Experimental evidence suggests that endocrine-disrupting chemicals (EDCs) can permanently disrupt the development of sexually dimorphic behaviors and the structure of sexually dimorphic areas of the brain. EDC exposure has different effects depending on diverse factors, such as the timing and dose of the exposure, the maternal environment and the individual's age and sex. Among EDCs, bisphenol A (BPA) is one of the most studied because of its extensive use, which ranges from dentistry to food/drink packaging. In the present study, we aimed to investigate the behavioral effects of developmental exposure to a low dose of BPA with respect to the timing of the exposure, maternal environment, sex and age at testing. Starting from the last week of pregnancy to the first postpartum week, dams spontaneously drank either corn oil (control group) or a solution containing BPA (10 ?g/kg bw/day). At birth, the litters were cross-fostered to different dams to differentiate among the effects of pre- and postnatal exposure. Pre- and postnatally exposed offspring underwent three diverse experimental paradigms for anxiety-related behaviors: as juveniles, a novelty test and at adulthood, both the free exploratory open field and elevated plus maze tests. At both testing ages, pre- and postnatally exposed females showed evidence of increased anxiety and were less prone to explore a novel environment relative to the control females, showing a behavioral profile more similar to control males than females. In this study, the direction of the behavioral changes was affected similarly by the pre- and postnatal exposures, resulting in a disruption of these sexually dimorphic behaviors, although with a greater effect associated with postnatal exposure primarily in females. Our findings indicate that non-reproductive, sexually dimorphic behaviors are sensitive to endocrine disruption during critical developmental periods-particularly the highly critical early neonatal stage. Combined with previous research, our study provides further evidence of the potential risks that even low doses of EDCs may pose to humans, with fetuses and infants being highly vulnerable. PMID:23470777

  4. Effects of time-variable exposure regimes of the insecticide chlorpyrifos on freshwater invertebrate communities in microcosms.

    PubMed

    Zafar, Mazhar Iqbal; Van Wijngaarden, Rene P A; Roessink, Ivo; Van den Brink, Paul J

    2011-06-01

    The present study compared the effects of different time-variable exposure regimes having the same time-weighted average (TWA) concentration of the organophosphate insecticide chlorpyrifos on freshwater invertebrate communities to enable extrapolation of effects across exposure regimes. The experiment was performed in outdoor microcosms by introducing three different regimes: a single application of 0.9?µg active ingredients (a.i.)/L; three applications of 0.3?µg a.i./L, with a time interval of 7?d; and continuous exposure to 0.1?µg a.i./L for 21?d. Measurements showed that the TWA(21d) concentration in the continuous-exposure treatment (0.098?µg/L) was slightly lower than in the three-application (0.116?µg/L) and single-application (0.126?µg/L) treatments. The application of chlorpyrifos resulted in decreased abundances in the arthropod community, with the largest adverse effects reported for the mayfly Cloeon dipterum and cladocerans Daphnia gr. longispina and Alona sp., while smaller effects were observed for other insects, copepods, and amphipods. At the population level, however, the mayfly C. dipterum only responded to the single-application treatment, which could be explained by the toxicokinetics of chlorpyrifos in this species. At the end of the experimental period the invertebrate community showed approximately the same effect magnitude for all treatment regimes. These results suggest that for this combination of concentrations and duration of the TWA, the TWA concentration is more important for most species than the peak concentration for the assessment of long-term risks of chlorpyrifos. PMID:21351295

  5. Effects of Exposure Time, Material Type, and Granular Pesticide on Glove Contamination

    Microsoft Academic Search

    C. Guo; J. Stone; H. M. Stahr; M. Shelley

    2001-01-01

    Chemical-resistant gloves are recommended for pesticide applicators to reduce their exposure to agricultural chemicals. In\\u000a this research, three chemical-resistant glove materials—nitrile, neoprene, and barrier laminate—were studied in relation to\\u000a contamination with granular terbufos and tefluthrin. Surfaces of specimens backed with alpha cellulose were contaminated with\\u000a 300 mg of either granular terbufos or tefluthrin for 1-, 2-, 4-, 8-, 16-, and

  6. Microstructural changes during long time service exposure of udimet 500 and nimonic 115

    Microsoft Academic Search

    A. K. Koul; W. Wallace

    1983-01-01

    The effects of long term service exposure on the microstructure of Udimet 500 and Nimonic 115 turbine engine components has\\u000a been studied. Sigma (?) phase was detected in both alloys, and its formation could be predicted using critical electron vacancy\\u000a concentrations computed by the revised method of Barrows and Newkirk and the experimental ? phase composition, ?? coarsening\\u000a was quite

  7. Exposure to Environmental Tobacco Smoke at Work, at Home, and During Leisure Time: Personal Exposure Measurements by Diffusive Sampling of Airborne 3-Ethenylpyridine

    Microsoft Academic Search

    Sinikka Vainiotalo; Kristiina Patja; Tiina Laatikainen; Leea Kuusimäki; Kimmo Peltonen; Erkki Vartiainen

    2008-01-01

    Environmental tobacco smoke (ETS) is associated with an increased risk of several diseases. In 2002, the ETS exposure level was studied in a Finnish cross-sectional population sample with a sub-sample of currently working nonsmokers. In all, 123 nonsmokers (25—64 years) reporting at least 1 h of daily exposure to ETS participated in personal exposure measurements. Two 3 M organic vapor

  8. Effect of exposure time on corrosion resistance of prepassivated UNS S31603 SS in the Gulf of Mexico

    SciTech Connect

    Acuiia, N.; Herniindet-Duque, G. [Univ. del Mayab, Merida (Mexico). Facultad de Ingenieria

    1998-12-31

    The effect of exposure time, in the Gulf of Mexico, on the UNS S3 1603 stainless steel (SS) pitting corrosion resistance (PCR), was studied for 30 days using both open circuit potential (OCP) and potentiodynamic polarization (PP) techniques. Biofilm formation and corrosion attack were subsequently observed using scanning electron microscope (SEM) and atomic force microscopy (AFM). It was found that microorganisms colonizing the steel specimen`s surface during the first three days of testing, modified the OCP towards electropositive values, increasing the risk of pitting corrosion. It was also observed, that the SS specimens were most sensitive to pitting corrosion within the first fifteen days of exposure in seawater, decreasing this sensitivity during the last week, probably due to a decay in the biological activity and better behavior of the passive film.

  9. Damage to stomata and inhibition of photosynthesis by toxic pollutants in Pinus sylvestris needles as affected by the exposure time

    SciTech Connect

    Kaipiainen, L.K.; Sofronova, G.I. [Institute of Forestry, Karelia (Russian Federation); Hari, P. [Helsinki Univ. (Finland)] [and others

    1995-11-01

    The impact of persistent exposure of Pinus sylvestris L. trees of various ages to industrial emissions on stomata and photosynthesis of needles was studied in relation to the exposure time. The electron microscopic examination of the needles revealed an erosion of the epicuticular wax and damage to stomata, which increased with needle age until stomata were completely occluded by polymetallic dust. Pollutant particles wee found to contain S, Cl, Ca, K, Mg, Mn, Al, Ni, Fe, Cu, Co, Ti, and Zn. Photosynthetic rates were inhibited by 20-60%, depending on the needle age and tree condition. It is concluded that a nonuniformity in the toxicant distribution over the forest canopy and the age-dependent changes in the state of the cuticular wax layer are the most likely causes of variability in the extent to which individual trees were damaged by the toxicants.

  10. Improvement of attention span and reaction time with hyperbaric oxygen treatment in patients with toxic injury due to mold exposure

    PubMed Central

    Ezra, N.; Dang, K.

    2010-01-01

    It is, by now, well established that mold toxins (mycotoxins) can cause significant adverse health effects. In this study, 15 subjects who developed an attention deficit disorder (ADD) and slowing of reaction time at the time of exposure to mold toxins were identified. Deficits in attention span and reaction time were documented not only by taking a careful history, but also by performing a Test of Variables of Attention (TOVA). The TOVA test provides an objective measure of these two variables. It was found that mold-exposed subjects show statistically significant decreases in attention span and significant increases in reaction time to stimuli compared to controls. After ten sessions of hyperbaric oxygen treatment (HBOT), a statistically significant improvement was seen in both measures. This preliminary study suggests promising outcomes in treating mold-exposed patients with hyperbaric oxygen. PMID:20978814

  11. Microstructural changes during long time service exposure of udimet 500 and nimonic 115

    NASA Astrophysics Data System (ADS)

    Koul, A. K.; Wallace, W.

    1983-02-01

    The effects of long term service exposure on the microstructure of Udimet 500 and Nimonic 115 turbine engine components has been studied. Sigma (?) phase was detected in both alloys, and its formation could be predicted using critical electron vacancy concentrations computed by the revised method of Barrows and Newkirk and the experimental ? phase composition, ?' coarsening was quite pronounced in Nimonic 115 turbine blades and varied as a strong function of the temperature distribution along the blade airfoil, ? phase precipitation had no effect on ?' coarsening rates.

  12. Near-Real-Time Analysis of the Phenotypic Responses of Escherichia coli to 1-Butanol Exposure Using Raman Spectroscopy

    PubMed Central

    Zu, Theresah N. K.; Athamneh, Ahmad I. M.; Wallace, Robert S.; Collakova, Eva

    2014-01-01

    Raman spectroscopy was used to study the time course of phenotypic responses of Escherichia coli (DH5?) to 1-butanol exposure (1.2% [vol/vol]). Raman spectroscopy is of interest for bacterial phenotyping because it can be performed (i) in near real time, (ii) with minimal sample preparation (label-free), and (iii) with minimal spectral interference from water. Traditional off-line analytical methodologies were applied to both 1-butanol-treated and control cells to draw correlations with Raman data. Here, distinct sets of Raman bands are presented that characterize phenotypic traits of E. coli with maximized correlation to off-line measurements. In addition, the observed time course phenotypic responses of E. coli to 1.2% (vol/vol) 1-butanol exposure included the following: (i) decreased saturated fatty acids levels, (ii) retention of unsaturated fatty acids and low levels of cyclopropane fatty acids, (iii) increased membrane fluidity following the initial response of increased rigidity, and (iv) no changes in total protein content or protein-derived amino acid composition. For most phenotypic traits, correlation coefficients between Raman spectroscopy and traditional off-line analytical approaches exceeded 0.75, and major trends were captured. The results suggest that near-real-time Raman spectroscopy is suitable for approximating metabolic and physiological phenotyping of bacterial cells subjected to toxic environmental conditions. PMID:25157078

  13. The Impact of Timing of Exposure to Violence on Violent Behavior in a High Poverty Sample of Inner City African American Youth

    ERIC Educational Resources Information Center

    Spano, Richard; Rivera, Craig; Bolland, John

    2006-01-01

    A growing body of research has linked exposure to violence to violent behavior, but few studies have examined the impact of the timing of exposure to violence on violent behavior among inner city, minority youth. Theoretical insights derived from developmental psychology and psychopathology (DPP) and Agnew's general strain theory (GST) give…

  14. A comparison of Reduced Life Expectancy (RLE) model with Haber's Rule to describe effects of exposure time on toxicity.

    PubMed

    Verma, Vibha; Yu, Qiming J; Connell, Des W

    2015-09-01

    The Reduced Life Expectancy (RLE) Model (LC50 = [ln(NLE) - ln(LT50)]/d) has been proposed as an alternative to Haber's Rule. The model is based on a linear relationship between LC50 (Lethal Exposure Concentration) and lnLT50 (Lethal Exposure Time) and uses NLE (Normal Life Expectancy) as a limiting point as well as a long term data point (where d is a constant). The purposes of this paper were to compare the RLE Model with Haber's Rule with available toxicity data and to evaluate the strengths and weaknesses of each approach. When LT50 is relatively short and LC50 is high, Haber's Rule is consistent with the RLE model. But the difference between the two was evident in the situation when LT50 is relatively long and LC50 is low where the RLE model is a marked departure from Haber's Rule. The RLE Model can be used to appropriately evaluate long term effects of exposure. PMID:25898234

  15. Ecological impacts of time-variable exposure regimes to the fungicide azoxystrobin on freshwater communities in outdoor microcosms.

    PubMed

    Zafar, Mazhar Iqbal; Belgers, J Dick M; Van Wijngaarden, Rene P A; Matser, Arriënne; Van den Brink, Paul J

    2012-05-01

    This paper evaluates the effects of different time-varying exposure patterns of the strobilurin fungicide azoxystrobin on freshwater microsocosm communities. These exposure patterns included two treatments with a similar peak but different time-weighted average (TWA) concentrations, and two treatments with similar TWA but different peak concentrations. The experiment was carried out in outdoor microcosms under four different exposure regimes; (1) a continuous application treatment of 10 ?g/L (CAT(10)) for 42 days (2), a continuous application treatment of 33 ?g/L (CAT(33)) for 42 days (3), a single application treatment of 33 ?g/L (SAT(33)) and (4) a four application treatment of 16 ?g/L (FAT(16)), with a time interval of 10 days. Mean measured 42-d TWA concentrations in the different treatments were 9.4 ?g/L (CAT(10)), 32.8 ?g/L (CAT(33)), 14.9 ?g/L (SAT(33)) and 14.7 ?g/L (FAT(16)). Multivariate analyses demonstrated significant changes in zooplankton community structure in all but the CAT(10) treated microcosms relative to that of controls. The largest adverse effects were reported for zooplankton taxa belonging to Copepoda and Cladocera. By the end of the experimental period (day 42 after treatment), community effects were of similar magnitude for the pulsed treatment regimes, although the magnitude of the initial effect was larger in the SAT(33) treatment. This indicates that for long-term effects the TWA is more important for most zooplankton species in the test system than the peak concentration. Azoxystrobin only slightly affected some species of the macroinvertebrate, phytoplankton and macrophyte assemblages. The overall no observed ecologically adverse effect concentrations (NOEAEC) in this study was 10 µg/L. PMID:22278367

  16. Survival Time Analysis of Least Killifish ( Heterandria formosa ) and Mosquitofish ( Gambusia affinis ) in Acute Exposures to Endosulfan Sulfate

    Microsoft Academic Search

    John F. Carriger; Tham C. Hoang; Gary M. Rand

    2010-01-01

    Single-species flow-through toxicity tests were conducted to determine the times-to-death of two indigenous fish to South\\u000a Florida—least killifish (Heterandria formosa) and mosquitofish (Gambusia affinis)—from acute exposure to endosulfan sulfate. Mortalities were recorded within 8-h periods from test initiation to termination\\u000a at 96 h. The 96-h LC50s for least killifish and mosquitofish estimated using the trimmed-Spearman–Karber method were 2.0 and 2.3 ?g\\/l, respectively.

  17. Exposure to static and time-varying magnetic fields from working in the static magnetic stray fields of MRI scanners: a comprehensive survey in the Netherlands.

    PubMed

    Schaap, Kristel; Christopher-De Vries, Yvette; Crozier, Stuart; De Vocht, Frank; Kromhout, Hans

    2014-11-01

    Clinical and research staff who work around magnetic resonance imaging (MRI) scanners are exposed to the static magnetic stray fields of these scanners. Although the past decade has seen strong developments in the assessment of occupational exposure to electromagnetic fields from MRI scanners, there is insufficient insight into the exposure variability that characterizes routine MRI work practice. However, this is an essential component of risk assessment and epidemiological studies. This paper describes the results of a measurement survey of shift-based personal exposure to static magnetic fields (SMF) (B) and motion-induced time-varying magnetic fields (dB/dt) among workers at 15 MRI facilities in the Netherlands. With the use of portable magnetic field dosimeters, >400 full-shift and partial shift exposure measurements were collected among various jobs involved in clinical and research MRI. Various full-shift exposure metrics for B and motion-induced dB/dt exposure were calculated from the measurements, including instantaneous peak exposure and time-weighted average (TWA) exposures. We found strong correlations between levels of static (B) and time-varying (dB/dt) exposure (r = 0.88-0.92) and between different metrics (i.e. peak exposure, TWA exposure) to express full-shift exposure (r = 0.69-0.78). On average, participants were exposed to MRI-related SMFs during only 3.7% of their work shift. Average and peak B and dB/dt exposure levels during the work inside the MRI scanner room were highest among technical staff, research staff, and radiographers. Average and peak B exposure levels were lowest among cleaners, while dB/dt levels were lowest among anaesthesiology staff. Although modest exposure variability between workplaces and occupations was observed, variation between individuals of the same occupation was substantial, especially among research staff. This relatively large variability between workers with the same job suggests that exposure classification based solely on job title may not be an optimal grouping strategy for epidemiological purposes. PMID:25139484

  18. Heat loss and tolerance time during cold exposure in heliox atmosphere at 16 ATA.

    PubMed

    Brubakk, A O; Tønjum, S; Holand, B; Peterson, R E; Hamilton, R W; Morild, E; Onarheim, J

    1982-06-01

    Four different types of protective clothing and three different methods of heat conservation protection were evaluated during an exposure to 4 degrees C cold in a heliox atmosphere at 150 msw. The divers using protective systems with little insulation had to quit the test after 1-2 h due to uncontrollable shivering and an extreme feeling of cold, whereas the divers using the heavily insulated clothing were able to stay in the chamber for 8-10 h. However, even with adequate protection against convective heat loss from the skin, respiratory convective heat loss will be high unless inspired gas is heated. This can be adequately done by using a combined heat-exchanger and scrubber where the heat produced by CO2 absorption is used to warm the inspired gas. PMID:7123699

  19. THE EXPOSURE PARADOX IN PARTICULATE MATTER COMMUNITY TIME-SERIES EPIDEMIOLOGY: CAN AMBIENT CONCENTRATIONS OF PM BE USED AS A SURROGATE FOR PERSONAL EXPOSURE TO PM ?

    EPA Science Inventory

    Objective: Explain why epidemiologic studies find a statistically significant relationship between ambient concentrations of PM and health effects even though only a near-zero correlation is found between ambient concentrations of PM and personal exposures to PM. Method: Consider...

  20. A simulation study on effects of exposure to a combination of pesticides used in an orchard and tuber crop on the recovery time of a vulnerable aquatic invertebrate.

    PubMed

    Focks, Andreas; Luttik, Robert; Zorn, Mathilde; Brock, Theo; Roex, Erwin; Van der Linden, Ton; Van den Brink, Paul J

    2014-07-01

    The aim of the present study was to assess whether population effects and recovery times increase when a population of a vulnerable aquatic invertebrate is exposed to concentrations of 1 or multiple pesticides. The 2 sets of pesticide combinations tested are typical for orchard and tuber crops in The Netherlands. Exposure concentrations were predicted using the FOCUS step 3 modeling framework and the Dutch drainage ditch scenario. Recovery times were assessed using the MASTEP population model. We simulated the population dynamics and pesticide effects in a Monte Carlo style by using median effective concentration values drawn from an arthropod species sensitivity distribution. In the tuber scenario, exposure to ?-cyhalothrin resulted in long-term effects, whereas exposure to the co-occurring compound fluazinam hardly resulted in (additional) effects. In the orchard scenario, 3 pesticides resulted in large effects just after exposure, but pulse exposures to these compounds did not coincide. The probabilities of effects for the single compounds added up for the combination; in contrast, the recovery times were not higher for the combination compared to those associated with exposure to the individual compounds. The conclusion from the present study's simulations is that exposure to the evaluated pesticide packages may lead to increased mortality probabilities and effect sizes of the combination, but does not lead to longer recovery times for populations with synchronized reproduction than when exposed to the individual compounds. PMID:24375456

  1. Multivariate nonlinear time series modeling of exposure and risk in road safety research

    Microsoft Academic Search

    F. Bijleveld; J. Commandeur; Montfort van K; S. J. Koopman

    2010-01-01

    A multivariate non-linear time series model for road safety data is presented. The model is applied in a case-study into the development of a yearly time series of numbers of fatal accidents (inside and outside urban areas) and numbers of kilometres driven by motor vehicles in the Netherlands between 1961 and 2000. The model accounts for missing entries in the

  2. Multivariate non-linear time series modelling of exposure and risk in road safety research

    Microsoft Academic Search

    Frits Bijleveld; Jacques Commandeur; Siem Jan Koopman; Kees van Montfort

    2010-01-01

    A multivariate non-linear time series model for road safety data is presented. The model is applied in a case-study into the development of a yearly time series of numbers of fatal accidents (inside and outside urban areas) and numbers of kilometres driven by motor vehicles in the Netherlands between 1961 and 2000. The model accounts for missing entries in the

  3. Assessment of critical exposure and outcome windows in time-to-event analysis with application to air pollution and preterm birth study.

    PubMed

    Chang, Howard H; Warren, Joshua L; Darrow, Lnydsey A; Reich, Brian J; Waller, Lance A

    2015-07-01

    In reproductive epidemiology, there is a growing interest to examine associations between air pollution exposure during pregnancy and the risk of preterm birth (PTB). One important research objective is to identify critical periods of exposure and estimate the associated effects at different stages of pregnancy. However, population studies have reported inconsistent findings. This may be due to limitations from the standard analytic approach of treating PTB as a binary outcome without considering time-varying exposures together over the course of pregnancy. To address this research gap, we present a Bayesian hierarchical model for conducting a comprehensive examination of gestational air pollution exposure by estimating the joint effects of weekly exposures during different vulnerable periods. Our model also treats PTB as a time-to-event outcome to address the challenge of different exposure lengths among ongoing pregnancies. The proposed model is applied to a dataset of geocoded birth records in the Atlanta metropolitan area between 1999-2005 to examine the risk of PTB associated with gestational exposure to ambient fine particulate matter [Formula: see text]m in aerodynamic diameter (PM[Formula: see text]). We find positive associations between PM[Formula: see text] exposure during early and mid-pregnancy, and evidence that associations are stronger for PTBs occurring around week 30. PMID:25572998

  4. exposure. In laser-heating tests, response times varied from tenths of microseconds to several

    E-print Network

    Odom, Teri W.

    in a moving automobile. Adding in the dimension of time leads into non- intuitive territory, as in the example coated with a self-assembled alkanethiol monolayer, and nickel wires were deposited. The arrays were

  5. Community variations in population exposure to near-field tsunami hazards as a function of pedestrian travel time to safety

    USGS Publications Warehouse

    Wood, Nathan J.; Schmidtlein, Mathew C.

    2013-01-01

    Efforts to characterize population exposure to near-field tsunami threats typically focus on quantifying the number and type of people in tsunami-hazard zones. To develop and prioritize effective risk-reduction strategies, emergency managers also need information on the potential for successful evacuations and how this evacuation potential varies among communities. To improve efforts to properly characterize and differentiate near-field tsunami threats among multiple communities, we assess community variations in population exposure to tsunamis as a function of pedestrian travel time to safety. We focus our efforts on the multiple coastal communities in Grays Harbor and Pacific Counties (State of Washington, USA), where a substantial resident and visitor population is threatened by near-field tsunamis related to a potential Cascadia subduction zone earthquake. Anisotropic, path-distance modeling is conducted to estimate travel times to safety and results are merged with various population data, including residents, employees, public venues, and dependent-care facilities. Results suggest that there is substantial variability among communities in the number of people that may have insufficient time to evacuate. Successful evacuations may be possible in some communities assuming slow-walking speeds, are plausible in others if travel speeds are increased, and are unlikely in another set of communities given the large distances and short time horizon. Emergency managers can use these results to prioritize the location and determine the most appropriate type of tsunami risk-reduction strategies, such as education and training in areas where evacuations are plausible and vertical-evacuation structures in areas where they are not.

  6. Time-location analysis for exposure assessment studies of children using a novel global positioning system instrument.

    PubMed Central

    Elgethun, Kai; Fenske, Richard A; Yost, Michael G; Palcisko, Gary J

    2003-01-01

    Global positioning system (GPS) technology is used widely for business and leisure activities and offers promise for human time-location studies to evaluate potential exposure to environmental contaminants. In this article we describe the development of a novel GPS instrument suitable for tracking the movements of young children. Eleven children in the Seattle area (2-8 years old) wore custom-designed data-logging GPS units integrated into clothing. Location data were transferred into geographic information systems software for map overlay, visualization, and tabular analysis. Data were grouped into five location categories (in vehicle, inside house, inside school, inside business, and outside) to determine time spent and percentage reception in each location. Additional experiments focused on spatial resolution, reception efficiency in typical environments, and sources of signal interference. Significant signal interference occurred only inside concrete/steel-frame buildings and inside a power substation. The GPS instruments provided adequate spatial resolution (typically about 2-3 m outdoors and 4-5 m indoors) to locate subjects within distinct microenvironments and distinguish a variety of human activities. Reception experiments showed that location could be tracked outside, proximal to buildings, and inside some buildings. Specific location information could identify movement in a single room inside a home, on a playground, or along a fence line. The instrument, worn in a vest or in bib overalls, was accepted by children and parents. Durability of the wiring was improved early in the study to correct breakage problems. The use of GPS technology offers a new level of accuracy for direct quantification of time-location activity patterns in exposure assessment studies. PMID:12515689

  7. Time Profile of Cosmic Radiation Exposure During the EXPOSE-E Mission: The R3DE Instrument

    PubMed Central

    Horneck, Gerda; Häder, Donat-Peter; Schuster, Martin; Richter, Peter; Lebert, Michael; Demets, Rene

    2012-01-01

    Abstract The aim of this paper is to present the time profile of cosmic radiation exposure obtained by the Radiation Risk Radiometer-Dosimeter during the EXPOSE-E mission in the European Technology Exposure Facility on the International Space Station's Columbus module. Another aim is to make the obtained results available to other EXPOSE-E teams for use in their data analysis. Radiation Risk Radiometer-Dosimeter is a low-mass and small-dimension automatic device that measures solar radiation in four channels and cosmic ionizing radiation as well. The main results of the present study include the following: (1) three different radiation sources were detected and quantified—galactic cosmic rays (GCR), energetic protons from the South Atlantic Anomaly (SAA) region of the inner radiation belt, and energetic electrons from the outer radiation belt (ORB); (2) the highest daily averaged absorbed dose rate of 426 ?Gy d?1 came from SAA protons; (3) GCR delivered a much smaller daily absorbed dose rate of 91.1 ?Gy d?1, and the ORB source delivered only 8.6 ?Gy d?1. The analysis of the UV and temperature data is a subject of another article (Schuster et al., 2012). Key Words: Ionizing radiation—R3D—ISS. Astrobiology 12, 403–411. PMID:22680687

  8. Close-range blast exposure is associated with altered functional connectivity in Veterans independent of concussion symptoms at time of exposure.

    PubMed

    Robinson, Meghan E; Lindemer, Emily R; Fonda, Jennifer R; Milberg, William P; McGlinchey, Regina E; Salat, David H

    2015-03-01

    Although there is emerging data on the effects of blast-related concussion (or mTBI) on cognition, the effects of blast exposure itself on the brain have only recently been explored. Toward this end, we examine functional connectivity to the posterior cingulate cortex, a primary region within the default mode network (DMN), in a cohort of 134 Iraq and Afghanistan Veterans characterized for a range of common military-associated comorbidities. Exposure to a blast at close range (<10 meters) was associated with decreased connectivity of bilateral primary somatosensory and motor cortices, and these changes were not different from those seen in participants with blast-related mTBI. These results remained significant when clinical factors such as sleep quality, chronic pain, or post traumatic stress disorder were included in the statistical model. In contrast, differences in functional connectivity based on concussion history and blast exposures at greater distances were not apparent. Despite the limitations of a study of this nature (e.g., assessments long removed from injury, self-reported blast history), these data demonstrate that blast exposure per se, which is prevalent among those who served in Iraq and Afghanistan, may be an important consideration in Veterans' health. It further offers a clinical guideline for determining which blasts (namely, those within 10 meters) are likely to lead to long-term health concerns and may be more accurate than using concussion symptoms alone. PMID:25366378

  9. Toxicogenomic Studies of the Rat Brain at an Early Time Point Following Acute Sarin Exposure

    Microsoft Academic Search

    Tirupapuliyur V. Damodaran; Stephen T. Greenfield; Anand G. Patel; Holly K. Dressman; Siomon K. Lin; Mohamed B. Abou-Donia

    2006-01-01

    We have studied sarin-induced global gene expression patterns at an early time point (2 h: 0.5×LD50) using Affymetrix Rat Neurobiology U34 chips and male Sprague–Dawley rats. A total of 46 genes showed statistically significant alterations from control levels. Three gene categories contained more of the altered genes than any other groups: ion channel (8 genes) and calcium channel and binding proteins

  10. Developmental Timing and Continuity of Exposure to Interparental Violence and Externalizing Behavior as Prospective Predictors of Dating Violence

    PubMed Central

    Narayan, Angela J.; Englund, Michelle M.; Egeland, Byron

    2014-01-01

    This study investigated the prospective pathways of children's exposure to interparental violence (EIPV) in early and middle childhood and externalizing behavior in middle childhood and adolescence as developmental predictors of dating violence perpetration and victimization at ages 23 and 26 years. Participants (N = 168) were drawn from a longitudinal study of low-income families. Path analyses examined whether timing or continuity of EIPV predicted dating violence and whether timing or continuity of externalizing behavior mediated these pathways. Results indicated that EIPV in early childhood directly predicted perpetration and victimization at age 23. There were significant indirect effects from EIPV to dating violence through externalizing behavior in adolescence and life stress at age 23. Independent of EIPV, externalizing behavior in middle childhood also predicted dating violence through externalizing behavior in adolescence and life stress at age 23, but this pathway stemmed from maltreatment. These results highlight that the timing of EIPV and both the timing and continuity of externalizing behavior are critical risks for the intergenerational transmission of dating violence. Findings support a developmental perspective that negative early experiences and children's externalizing behavior are powerful influences for dating violence in early adulthood. PMID:24229543

  11. Modelling personal exposure to particulate air pollution: an assessment of time-integrated activity modelling, Monte Carlo simulation & artificial neural network approaches.

    PubMed

    McCreddin, A; Alam, M S; McNabola, A

    2015-01-01

    An experimental assessment of personal exposure to PM10 in 59 office workers was carried out in Dublin, Ireland. 255 samples of 24-h personal exposure were collected in real time over a 28 month period. A series of modelling techniques were subsequently assessed for their ability to predict 24-h personal exposure to PM10. Artificial neural network modelling, Monte Carlo simulation and time-activity based models were developed and compared. The results of the investigation showed that using the Monte Carlo technique to randomly select concentrations from statistical distributions of exposure concentrations in typical microenvironments encountered by office workers produced the most accurate results, based on 3 statistical measures of model performance. The Monte Carlo simulation technique was also shown to have the greatest potential utility over the other techniques, in terms of predicting personal exposure without the need for further monitoring data. Over the 28 month period only a very weak correlation was found between background air quality and personal exposure measurements, highlighting the need for accurate models of personal exposure in epidemiological studies. PMID:25260856

  12. Consequences of ethanol exposure on cued and contextual fear conditioning and extinction differ depending on timing of exposure during adolescence or adulthood.

    PubMed

    Broadwater, Margaret; Spear, Linda P

    2013-11-01

    Some evidence suggests that adolescents are more sensitive than adults to ethanol-induced cognitive deficits and that these effects may be long-lasting. The purpose of Exp 1 was to determine if early-mid adolescent [postnatal day (P) 28-48] intermittent ethanol exposure would affect later learning and memory in a Pavlovian fear conditioning paradigm differently than comparable exposures in adulthood (P70-90). In Exp 2 animals were exposed to ethanol during mid-late adolescence (P35-55) to assess whether age of initiation within the adolescent period would influence learning and memory differentially. Male Sprague-Dawley rats were given 4 g/kg i.g. ethanol (25%) or water every 48 h for a total of 11 exposures. After a 22 day non-ethanol period, animals were fear conditioned to a context (relatively hippocampal-dependent task) or tone (amygdala-dependent task), followed by retention tests and extinction (mPFC-dependent) of this conditioning. Despite similar acquisition, a deficit in context fear retention was evident in animals exposed to ethanol in early adolescence, an effect not observed after a comparable ethanol exposure in mid-late adolescence or adulthood. In contrast, animals that were exposed to ethanol in mid-late adolescence or adulthood showed enhanced resistance to context extinction. Together these findings suggest that repeated ethanol imparts long-lasting consequences on learning and memory, with outcomes that differ depending on age of exposure. These results may reflect differential influence of ethanol on the brain as it changes throughout ontogeny and may have implications for alcohol use not only throughout the developmental period of adolescence, but also in adulthood. PMID:23938333

  13. SHEAR BOND STRENGTH OF METALLIC BRACKETS PHOTO-ACTIVATED WITH LIGHT-EMITTING DIODE (LED) AT DIFFERENT EXPOSURE TIMES

    PubMed Central

    Rêgo, Emanuel Braga; Romano, Fábio Lourenço

    2007-01-01

    The purpose of this study was to compare the shear bond strength of orthodontic metallic brackets photo-activated with two different light-curing sources at different exposure times: halogen light (XL 1500, 3M ESPE) and LED light (Ortholux, 3M Unitek). Sixty bovine permanent lower incisors were inserted into PVC tubes containing plaster. The buccal surfaces were cleaned with pumice and water, and then etched with 37% phosphoric acid gel. The XT Primer bonding agent (3M Unitek) was applied to the enamel surfaces and the metallic pre-coated brackets (Transbond APC II system, 3M Unitek) were attached to upper central incisors. The teeth were randomly divided into four groups (n=15). In Group I (Control), halogen light was used for 40 seconds, while in Groups II, III, and IV were light-cured with LED light unit for 40, 10, and 5 seconds, respectively. The teeth were stored in distilled water at 37°C for 24 hours. The brackets were submitted to shear bond strength test in universal testing machine (Instron) at a crosshead speed of 0.5 mm/minute. Shear bond strength means (MPa) were 4.87 for Group I; 5.89 for Group II; 4.83 for Group III, and 4.39 for Group IV. Tukey's test detected no statistically significant differences among the groups regarding the shear bond strength (p>0.05). Neither of the types of light-curing sources or exposure times influenced the shear bond strength of metallic brackets. PMID:19089170

  14. Bioaccumulation of polychlorinated dibenzo-p-dioxins in sediment by oligochaetes: Influence of exposure pathway and contact time

    SciTech Connect

    Loonen, H.; Parsons, J.R.; Govers, H.A.J. [Univ. of Amsterdam (Netherlands). Dept. of Environmental and Toxicological Chemistry; Muir, D.C.G. [Dept. of Fisheries and Oceans, Winnipeg, Manitoba (Canada). Freshwater Inst.

    1997-07-01

    Oligochaetes (Lumbriculus variegatus) were exposed simultaneously to radiolabeled [{sup 3}H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and [{sup 14}C]octachlorodibenzo-p-dioxin (OCDD) in sediment for 28 d, in order to study accumulation processes of hydrophobic substances. Elimination was studied for a further 20 d. The uptake and elimination rate constants and the bioaccumulation factors (BAFs) were determined for TCDD and OCDD in the presence and absence of sediment (overlying water). Steady-state concentrations in oligochaetes were achieved for TCDD but not for OCDD over the 28-d exposure. Biota-sediment accumulation factors (BSAFs) after a 28-d exposure were 1.6 {+-} 0.27 for TCDD and 0.07 {+-} 0.02 for OCDD. Steady-state log BAF values (lipid based) for TCDD and OCDD in oligochaetes in the overlying water were 5.9 and 5.5 L/kg, respectively. The effect of incubation time between sediment and contaminants was investigated by repeating the accumulation study after a contact period of 21 months. BSAFs of sediment-sorbed TCDD and OCDD were 1.5 to 2-fold lower for the long contact time sediment. Based on comparison of predicted accumulation from pore water and observed accumulation by sediment-exposed oligochaetes, it was concluded that 1.4-fold greater accumulation occurred due to assimilation of TCDD and OCDD from ingested sediment. This additional accumulation in the presence of sediment, not accounted for by uptake only from pore waters, was consistent with literature data for other hydrophobic organochlorines.

  15. The solar UV exposure time required for vitamin D3 synthesis in the human body estimated by numerical simulation and observation in Japan

    NASA Astrophysics Data System (ADS)

    Nakajima, Hideaki; Miyauchi, Masaatsu; Hirai, Chizuko

    2013-04-01

    After the discovery of Antarctic ozone hole, the negative effect of exposure of human body to harmful solar ultraviolet (UV) radiation is widely known. However, there is positive effect of exposure to UV radiation, i.e., vitamin D synthesis. Although the importance of solar UV radiation for vitamin D3 synthesis in the human body is well known, the solar exposure time required to prevent vitamin D deficiency has not been well determined. This study attempted to identify the time of solar exposure required for vitamin D3 synthesis in the body by season, time of day, and geographic location (Sapporo, Tsukuba, and Naha, in Japan) using both numerical simulations and observations. According to the numerical simulation for Tsukuba at noon in July under a cloudless sky, 2.3 min of solar exposure are required to produce 5.5 ?g vitamin D3 per 600 cm2 skin. This quantity of vitamin D represents the recommended intake for an adult by the Ministry of Health, Labour and Welfare, and the 2010 Japanese Dietary Reference Intakes (DRIs). In contrast, it took 49.5 min to produce the same amount of vitamin D3 at Sapporo in the northern part of Japan in December, at noon under a cloudless sky. The necessary exposure time varied considerably with the time of the day. For Tsukuba at noon in December, 14.5 min were required, but at 09:00 68.7 min were required and at 15:00 175.8 min were required for the same meteorological conditions. Naha receives high levels of UV radiation allowing vitamin D3 synthesis almost throughout the year. According to our results, we are further developing an index to quantify the necessary time of UV radiation exposure to produce required amount of vitamin D3 from a UV radiation data.

  16. Adult asthma and traffic exposure at residential address, workplace address, and self-reported daily time outdoor in traffic: A two-stage case-control study

    PubMed Central

    2010-01-01

    Background Most epidemiologic studies use traffic at residential address as a surrogate for total traffic exposure when investigating effects of traffic on respiratory health. This study used GIS (Geographical Information Systems) to estimate traffic exposure, not only on residential, but also on workplace address, in addition to survey questions on time spent in traffic during commuting or other daily activities. The aim was to investigate 1) if there is an association between traffic exposure and prevalence of adult asthma and asthma symptoms, and 2) if so, does this association become stronger using more complete traffic exposure information. Methods This study was conducted in two stages: A first cross-sectional survey in Southern Sweden 2004 (n = 24819, 18-80 years, response rate 59%) was followed by a case-control study in 2005 to obtain more detailed exposure and confounder information (n = 2856, asthmatics and controls (1:3), 86% response rate). In the first survey, only residential address was known. In the second survey, questions about workplace addresses and daily time spent in traffic were also included. Residential and workplace addresses were geocoded and linked with GIS to road data and dispersion modelled outdoor concentrations of NOx (annual mean, 250 × 250 m resolution). Results Living within 50 m of a road (measured by GIS) with traffic intensity of >10 cars/minute (compared with no road within this distance) was associated with an increased prevalence of asthma, (OR = 1.8, 95% CI = (1.1-2.8), and with asthma symptoms last 12 months. No statistically significant effects were seen for traffic exposure at workplace address, daily time spent in traffic, or commuting time to work, after adjustment for confounders. A combined total exposure estimate did not give a stronger association with asthma prevalence or asthma symptoms. Conclusions Traffic exposure at close proximity to residential address showed association with asthma prevalence and asthma symptoms last 12 months, among adults in southern Sweden. The associations were not stronger when accounting for total traffic exposure. This could reflect exposure misclassfication at workplace address and for other daily time in traffic, but also that residential address remains the main determinant for traffic exposure among adults. PMID:21092159

  17. Power law signature of media exposure in human response waiting time distributions

    NASA Astrophysics Data System (ADS)

    Crane, Riley; Schweitzer, Frank; Sornette, Didier

    2010-05-01

    We study the humanitarian response to the destruction brought by the tsunami generated by the Sumatra earthquake of December 26, 2004, as measured by donations, and find that it decays in time as a power law ˜1/t? with ?=2.5±0.1 . This behavior is suggested to be the rare outcome of a priority queuing process in which individuals execute tasks at a rate slightly faster than the rate at which new tasks arise. We believe this to be an empirical evidence documenting the recently predicted [G. Grinstein and R. Linsker, Phys. Rev. E 77, 012101 (2008)] regime, and provide additional independent evidence that suggests that this “highly attentive regime” arises as a result of the intense focus placed on this donation “task” by the media.

  18. Evidence that high-dosage zidovudine at time of retrovirus exposure reduces antiviral efficacy.

    PubMed Central

    Mathes, L E; Hayes, K A; Kociba, G

    1996-01-01

    The antiviral efficacy of prophylactic 3'-azido-3'-deoxythymidine (AZT) therapy administered by continuous infusion or intermittent injection was compared in pediatric cats infected with feline leukemia virus. A 4-week treatment regimen of AZT was initiated at -48, 8, or 96 h postinfection (p.i.). For AZT therapy begun at -48 h p.i., significant efficacy was attained when therapy was given by continuous infusion but not by intermittent injection. However, when AZT therapy was delayed until 96 h p.i., both continuous infusion and intermittent injection gave complete protection. The results suggest that intermittent AZT administration is less efficacious than continuous infusion. Higher peak AZT concentrations in plasma associated with intermittent injection compared with those associated with continuous infusion may be immunotoxic, thus reducing the drug-induced vaccine effect. Furthermore, AZT toxicity seemed to be restricted to a window of sensitivity close to the time of virus challenge because delaying the start of AZT therapy until 96 h p.i. was highly efficacious, regardless of the method of administration. PMID:8878603

  19. Timing of Concussion Diagnosis is Related to Head Impact Exposure Prior to Injury

    PubMed Central

    Beckwith, Jonathan G.; Greenwald, Richard M.; Chu, Jeffrey J.; Crisco, Joseph J.; Rowson, Steven; Duma, Stefan M.; Broglio, Steven P.; McAllister, Thomas W.; Guskiewicz, Kevin M.; Mihalik, Jason P.; Anderson, Scott; Schnebel, Brock; Brolinson, P. Gunnar; Collins, Michael W.

    2012-01-01

    Purpose Concussions are commonly undiagnosed in an athletic environment because the post-injury signs and symptoms may be mild, masked by the subject, or unrecognized. This study compares measures of head impact frequency, location and kinematic response prior to cases of immediate and delayed concussion diagnosis. Methods Football players from eight collegiate and six high school teams wore instrumented helmets during play (n=1,208), of which ninety-five were diagnosed with concussion (105 total cases). Acceleration data recorded by the instrumented helmets was reduced to five kinematic metrics: peak linear and rotational acceleration, GSI, HIC15, and change in head velocity (?v). Additionally, each impact was assigned to one of four general location regions (Front, Back, Side, and Top), and the number of impacts sustained prior to injury was calculated over two time periods (one and seven days). Results All head kinematic measures associated with injury, except peak rotational acceleration (p = 0.284), were significantly higher for cases of immediate diagnosis than delayed diagnosis (p<0.05). Players with delayed diagnosis sustained a significantly higher number of head impacts on the day of injury (32.9 ±24.9; p < 0.001) and within seven days of injury (69.7 ±43.3; p = 0.006) than players with immediate diagnosis (16.5 ±15.1 and 50.2 ±43.6). Impacts associated with concussion occurred most frequently to the Front of the head (46%) followed by the Top (25%), Side (16%), and Back (13%) with the number of impacts by location independent of temporal diagnosis (?2(3) = 4.72; p = 0.19). Conclusions Concussions diagnosed immediately after an impact event are associated with the highest kinematic measures, while those characterized by delayed diagnosis are preceded by a higher number of impacts. PMID:23135364

  20. Effect of time of exposure to rat coronavirus and Mycoplasma pulmonis on respiratory tract lesions in the Wistar rat.

    PubMed Central

    Schunk, M K; Percy, D H; Rosendal, S

    1995-01-01

    The effects of time of exposure on the progression of pulmonary lesions in rats inoculated with Mycoplasma pulmonis and the rat coronavirus, sialodacryoadenitis virus (SDAV) were studied, using six groups of 18 SPF Wistar rats (n = 108). Rats were inoculated intranasally as follows: Group 1, sterile medium only; Group 2, sterile medium followed one week later by 150 TCID50 SDAV; Group 3, sterile medium followed by 10(5.7) colony forming units of M. pulmonis; Group 4, SDAV followed one week later by M. pulmonis; Group 5, M. pulmonis followed one week later by SDAV; Group 6, M. pulmonis followed two weeks later by SDAV. Six rats from each group were euthanized at one, two and three weeks after the final inoculation. In a separate experiment, six additional animals were inoculated in each of groups 3, 5 and 6 (n = 18) and were sampled at five weeks after they had received M. pulmonis. Bronchoalveolar lavage and quantitative lung mycoplasma cultures were conducted on two-thirds of the rats. Histopathological examination and scoring of lesion severity were performed on all animals. Based on the prevalence and extent of histopathological lesions, bronchoalveolar lavage cell numbers, neutrophil differential cell counts and the isolation of M. pulmonis, the most severe disease occurred in the groups that received both agents. There was no significant difference in lesion severity between the groups receiving both agents other than in those examined during the acute stages of SDAV infection. Based on these results, it is evident that SDAV enhances lower respiratory tract disease in Wistar rats whether exposure occurs at one week prior to or at various intervals following M. pulmonis infections. Images Fig. 1. Fig. 2. Fig. 4. PMID:7704844

  1. Effect of acute bull exposure around the time of artificial insemination on serum oxytocin and progesterone concentrations and pregnancy rates in dairy cows.

    PubMed

    Ababneh, M M; Obeidat, I N; Husein, M Q; Talafha, A Q

    2013-04-01

    This study examined the effect of acute bull exposure around the time of artificial insemination (AI) on oxytocin and progesterone concentrations, and pregnancy rates in dairy cows. Ninety six dairy cows, stratified according to parity into primiparous and pluriparous, were divided into three groups; short bull exposure (SBE; 10 min, n = 32), long bull exposure (LBE; 4 h, n = 32) or no bull exposure (NBE; n = 32). On day 45 post-partum, all cows were treated with PGF2? on three occasions 11-14 days apart to synchronize oestrus. They were submitted to fixed time AI 80 h after the third PGF2? injection. Cows in the SBE and LBE groups were artificially inseminated 5 min after the introduction of the bull. From a subset of cows (n = 6 per group; three primiparous and three pluriparous), blood samples were collected once every 5 min starting 15 min before AI until 15 min after AI and analysed for oxytocin concentrations. Additional blood samples were collected for measurements of progesterone (P4) concentrations once daily for 4 days starting on the day of AI and once every 3 days thereafter until day 22. The effects of bull exposure, time, parity, difficulty of AI, and pregnancy on oxytocin and P4 concentrations were analysed using the mixed linear model procedure. Mean oxytocin concentrations or change in oxytocin concentrations after bull exposure or AI were not different among groups. Pregnancy rates for the NBE, SBE and LBE groups were 55.5%, 33.3% and 44.4%, respectively, and were not different among groups. In conclusion, acute bull exposure around the time of AI did not affect oxytocin and progesterone concentrations and did not improve pregnancy rates in dairy cattle under these farms conditions. PMID:22712677

  2. Real-time measurement of radiation exposure to patients during diagnostic coronary angiography and percutaneous interventional procedures

    Microsoft Academic Search

    Jack T Cusma; Malcolm R Bell; Merrill A Wondrow; Jerome P Taubel; David R Holmes

    1999-01-01

    ObjectivesThe aim of this study was to accurately assess the radiation exposure received by patients during cardiac catheterization in a large sample representative of the current state of practice in cardiac angiography.BackgroundRadiation exposure to patients and laboratory staff has been recognized as a necessary hazard in coronary angiography. The effects on x-ray exposure of the increased complexity of coronary angiographic

  3. Worker Exposure and High Time-Resolution Analyses of Process-Related Submicrometre Particle Concentrations at Mixing Stations in Two Paint Factories.

    PubMed

    Koponen, Ismo Kalevi; Koivisto, Antti Joonas; Jensen, Keld Alstrup

    2015-07-01

    The paint and coatings industry is known to have significant particulate matter (PM) emissions to the atmosphere. However, exposure levels are not studied in detail especially when considering submicrometre (PM1) and ultrafine particles (particle diameter below 100nm). The evidence is increasing that pulmonary exposures to these size fractions are potentially very harmful. This study investigates particle emissions during powder handling and paint mixing in two paint factories at two mixing stations in each factory. In each case measurements were made simultaneously at the mixing station (near-field; NF), as well as at 5-15 m distance into the workroom far-field (FF), and in the workers breathing zone. Particle concentrations (5nm to 30 µm) were measured using high time-resolution particle instruments and gravimetrically using PM1 cyclone filter samplers. The PM1 filters were also characterized by scanning electron microscopy (SEM). The NF particle and dust concentration levels were linked to pouring powder and were used to characterize the emissions and efficiencies of localized controls. NF particle number concentrations were 1000-40000cm(-3) above FF concentrations. NF particles were mainly between 100 and 500nm and emissions appeared to occur in short bursts. Personal PM1 exposure levels varied between 0.156 and 0.839mg m(-3) and were 1.6-15 times higher than stationary NF PM1 concentrations. SEM results verified that the personal exposure and NF particles were strongly dominated by the pigments and fillers used. Better understanding of the entire temporal personal exposure could be improved by using real-time particle monitors for personal exposure measurements. This study provides better insight into PM exposure characteristics and concentration levels in the paint industry. PMID:25863226

  4. Air pollution and early deaths in the United States. Part II: Attribution of PM2.5 exposure to emissions species, time, location and sector

    NASA Astrophysics Data System (ADS)

    Dedoussi, Irene C.; Barrett, Steven R. H.

    2014-12-01

    Combustion emissions constitute the largest source of anthropogenic emissions in the US, and lead to the degradation of air quality and human health. In Part I we computed the population fine particulate matter (PM2.5) exposure and number of early deaths caused by emissions from six major sectors: electric power generation, industry, commercial and residential activities, road transportation, marine transportation and rail transportation. In Part II we attribute exposure and early deaths to sectors, emissions species, time of emission, and location of emission. We apply a long-term adjoint sensitivity analysis and calculate the four dimensional sensitivities (time and space) of PM2.5 exposure with respect to each emissions species. Epidemiological evidence is used to relate increased population exposure to premature mortalities. This is the first regional application of the adjoint sensitivity analysis method to characterize long-term air pollution exposure. (A global scale application has been undertaken related to intercontinental pollution.) We find that for the electric power generation sector 75% of the attributable PM2.5 exposure is due to SO2 emissions, and 80% of the annual impacts are attributed to emissions from April to September. In the road transportation sector, 29% of PM2.5 exposure is due to NOx emissions and 33% is from ammonia (NH3), which is a result of emissions after-treatment technologies. We estimate that the benefit of reducing NH3 emissions from road transportation is ?20 times that of NOx per unit mass. 75% of the road transportation ammonia impacts occur during the months October to March. We publicly release the sensitivity matrices computed, noting their potential use as a rapid air quality policy assessment tool.

  5. Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye

    NASA Astrophysics Data System (ADS)

    Michael, Ralph; Wegener, Alfred

    2004-08-01

    Hazards from the optical radiation of an operating microscope that cause damage at the corneal, lenticular, and retinal levels were investigated; we considered, in particular, ultraviolet radiation (UVR) and blue light. The spectral irradiance from a Zeiss operation microscope OPMI VISU 200 was measured in the corneal plane between 300 and 1100 nm. Effective irradiance and radiance were calculated with relative spectral effectiveness data from the American Conference for Governmental and Industrial Hygienists. Safe exposure time to avoid UVR injury to the lens and cornea was found to be 2 h without a filter, 4 h with a UVR filter, 200 h with a yellow filter, and 400 h with a filter combination. Safe exposure time to avoid retinal photochemical injury was found to be 3 min without a filter and with a UVR filter, 10 min with a yellow filter, and 49 min with a filter combination. The effective radiance limit for retinal thermal injury was not exceeded. The hazard due to the UVR component from the operating microscope is not critical, and operation time can be safely prolonged with the use of appropriate filters. The retinal photochemical hazard appears critical without appropriate filters, permitting only some minutes of safe exposure time. The calculated safe exposure times are for worst-case conditions and maximal light output and include a safety factor.

  6. Air pollution exposure during critical time periods in gestation and alterations in cord blood lymphocyte distribution: a cohort of livebirths

    Microsoft Academic Search

    Caroline EW Herr; Miroslav Dostal; Rakesh Ghosh; Paul Ashwood; Michael Lipsett; Kent E Pinkerton; Radim Sram; Irva Hertz-Picciotto

    2010-01-01

    BACKGROUND: Toxic exposures have been shown to influence maturation of the immune system during gestation. This study investigates the association between cord blood lymphocyte proportions and maternal exposure to air pollution during each gestational month. METHODS: Cord blood was analyzed using a FACSort flow cytometer to determine proportions of T lymphocytes (CD3+ cells and their subsets, CD4+ and CD8+), B

  7. THE TIME-COURSE AND SENSITIVITY OF MUCONIC ACID AS A BIOMARKER FOR HUMAN ENVIRONMENTAL EXPOSURE TO BENZENE

    EPA Science Inventory

    Preliminary results are presented that show the effect of an increased benzene exposure on the urinary elimination of trans,trans-muconic acid (MA) for an adult male. These results were generated from a controlled exposure experiment where by an individual was exposed to benzene ...

  8. Time-dependent effects of waterborne copper exposure influencing hepatic lipid deposition and metabolism in javelin goby Synechogobius hasta and their mechanism.

    PubMed

    Huang, Chao; Chen, Qi-Liang; Luo, Zhi; Shi, Xi; Pan, Ya-Xiong; Song, Yu-Feng; Zhuo, Mei-Qin; Wu, Kun

    2014-10-01

    The present study was conducted to determine the time-course of waterborne chronic copper (Cu) exposure effects influencing hepatic lipid deposition and metabolism in javelin goby Synechogobius hasta and their mechanisms. S. hasta were exposed to four waterborne Cu concentrations (2 (control), 18, 38 and 55 ?g Cu/l) for 60 days. Sampling occurred on day 30 and day 60, respectively. Survival decreased and hepatic Cu content increased with increasing Cu levels. On day 30, Cu exposure increased hepatic lipid content, viscerosomatic index (VSI) and hepatosomatic index (HSI), and activities of lipogenic enzymes (6PGD, G6PD, ME, ICDH and FAS) as well as the mRNA levels of 6PGD, G6PD, ME, FAS, ACC?, LPL, PPAR? and SREBP-1 in the liver. However, the mRNA levels of ATGL, HSL and PPAR? declined following Cu exposure. On day 60, Cu exposure reduced hepatic lipid content, HSI, VSI, activities of G6PD, ME, ICDH and FAS, and the mRNA expression of 6PGD, G6PD, ME, FAS and SREBP-1, but increased mRNA expression of CPT 1, HSL and PPAR?. The differential Pearson correlation between transcriptional changes of genes encoding transcription factors (PPAR?, PPAR? and SREBP-1), and the activities and mRNA expression of enzymes involved in lipogenesis and lipolysis were observed on day 30 and day 60, respectively. Cu exposure for 30 days induced hepatic lipid accumulation by stimulating lipogenesis and inhibiting lipolysis. However, 60-day Cu exposure reduced hepatic lipid content by inhibiting lipogenesis and stimulating lipolysis. To our knowledge, for the first time, the present study provided experimental evidence that waterborne chronic Cu exposure differentially influenced genes involved in lipogenic and lipolytic metabolic pathway and the enzymes encoded in a duration-dependent manner in fish, and provided new insight into the relationship between metal toxicity and lipid metabolism. PMID:25087000

  9. The impact of missing data on analyses of a time-dependent exposure in a longitudinal cohort: a simulation study

    PubMed Central

    2013-01-01

    Background Missing data often cause problems in longitudinal cohort studies with repeated follow-up waves. Research in this area has focussed on analyses with missing data in repeated measures of the outcome, from which participants with missing exposure data are typically excluded. We performed a simulation study to compare complete-case analysis with Multiple imputation (MI) for dealing with missing data in an analysis of the association of waist circumference, measured at two waves, and the risk of colorectal cancer (a completely observed outcome). Methods We generated 1,000 datasets of 41,476 individuals with values of waist circumference at waves 1 and 2 and times to the events of colorectal cancer and death to resemble the distributions of the data from the Melbourne Collaborative Cohort Study. Three proportions of missing data (15, 30 and 50%) were imposed on waist circumference at wave 2 using three missing data mechanisms: Missing Completely at Random (MCAR), and a realistic and a more extreme covariate-dependent Missing at Random (MAR) scenarios. We assessed the impact of missing data on two epidemiological analyses: 1) the association between change in waist circumference between waves 1 and 2 and the risk of colorectal cancer, adjusted for waist circumference at wave 1; and 2) the association between waist circumference at wave 2 and the risk of colorectal cancer, not adjusted for waist circumference at wave 1. Results We observed very little bias for complete-case analysis or MI under all missing data scenarios, and the resulting coverage of interval estimates was near the nominal 95% level. MI showed gains in precision when waist circumference was included as a strong auxiliary variable in the imputation model. Conclusions This simulation study, based on data from a longitudinal cohort study, demonstrates that there is little gain in performing MI compared to a complete-case analysis in the presence of up to 50% missing data for the exposure of interest when the data are MCAR, or missing dependent on covariates. MI will result in some gain in precision if a strong auxiliary variable that is not in the analysis model is included in the imputation model. PMID:23947681

  10. Radiation Metabolomics. 2. Dose- and Time-Dependent Urinary Excretion of Deaminated Purines and Pyrimidines after Sublethal Gamma-Radiation Exposure in Mice

    PubMed Central

    Tyburski, John B.; Patterson, Andrew D.; Krausz, Kristopher W.; Slavík, Josef; Fornace, Albert J.; Gonzalez, Frank J.; Idle, Jeffrey R.

    2009-01-01

    Gamma-radiation exposure of humans is a major public health concern as the threat of terrorism and potential hostile use of radiological devices increases worldwide. We report here the effects of sublethal ?-radiation exposure on the mouse urinary metabolome determined using ultra-performance liquid chromatography-coupled time-of-flight mass spectrometry-based metabolomics. Five urinary biomarkers of sublethal radiation exposure that were statistically significantly elevated during the first 24 h after exposure to doses ranging from 1 to 3 Gy were unequivocally identified by tandem mass spectrometry. These are deaminated purine and pyrimidine derivatives, namely, thymidine, 2?-deoxyuridine, 2?-deoxyxanthosine, xanthine and xanthosine. Furthermore, the aminopyrimidine 2?-deoxycytidine appeared to display reduced urinary excretion at 2 and 3 Gy. The elevated biomarkers displayed a time-dependent excretion, peaking in urine at 8–12 h but returning to baseline by 36 h after exposure. It is proposed that 2?-deoxyuridine and 2?-deoxyxanthosine arise as a result of ? irradiation by nitrosative deamination of 2?-deoxycytidine and 2?-deoxyguanosine, respectively, and that this further leads to increased synthesis of thymidine, xanthine and xanthosine. The urinary excretion of deaminated purines and pyrimidines, at the expense of aminopurines and aminopyrimidines, appears to form the core of the urinary radiation metabolomic signature of mice exposed to sublethal doses of ionizing radiation. PMID:19580506

  11. Antibacterial activity of oregano oil against antibiotic resistant Salmonella enterica on organic leafy greens at varying exposure times and storage temperatures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to evaluate the effectiveness of oregano oil on four organic leafy greens (iceberg and romaine lettuces and mature and baby spinaches) inoculated with Salmonella Newport as a function of treatment exposure times as well as storage temperatures. Leaf samples were wash...

  12. ADAPTATION OF NATURAL MICROBIAL MMUNITIES TO DEGRADATION OF XENOBIOTIC COMPOUNDS: EFFECTS OF CONCENTRATION, EXPOSURE TIME, INOCULUM, AND CHEMICAL STRUCTURE

    EPA Science Inventory

    Adaptation of microbial populations to degrade xenobiotic compounds faster after exposure to the compound was studied in eco-cores. Radiolabeled test compounds were added to cores that contained natural water and sediment samples. Adaptation was detected by comparing mineralizati...

  13. Hypothetical exposure limits for oil-based metalworking fluids and cardiovascular mortality in a cohort of autoworkers: structural accelerated failure time models in a public health framework.

    PubMed

    Picciotto, Sally; Peters, Annette; Eisen, Ellen A

    2015-04-15

    Occupational exposure to aerosolized particles of oil-based metalworking fluid was recently linked to deaths from ischemic heart disease. The current recommended exposure limits might be insufficient. Studying cardiovascular mortality is challenging because symptoms can induce sicker workers to reduce their exposure, causing healthy-worker survivor bias. G-estimation of accelerated failure time models reduces this bias and permits comparison of multiple exposure interventions. Michigan autoworkers from the United AutoWorkers-General Motors cohort (n = 38,666) were followed from 1941 through 1994. Separate binary variables indicated whether annual exposure exceeded a series of potential limits. Separate g-estimation analyses for each limit yielded the total number of life-years that could have been saved among persons who died from specific cardiovascular causes by enforcing that exposure limit. Banning oil-based fluids would have saved an estimated 4,003 (95% confidence interval: 2,200, 5,807) life-years among those who died of ischemic heart disease. Estimates for cardiovascular disease overall, acute myocardial infarction, and cerebrovascular disease were 3,500 (95% confidence interval: 1,350, 5,651), 2,932 (95% confidence interval: 1,587, 4,277), and 917 (95% confidence interval: -80, 1,913) life-years, respectively. A limit of 0.01 mg/m(3) would have had a similar impact on cerebrovascular disease but one only half as great on ischemic heart disease. Analyses suggest that limiting exposure to metalworking fluids could have saved many life-years lost to cardiovascular diseases in this cohort. PMID:25816818

  14. Hypothetical Exposure Limits for Oil-Based Metalworking Fluids and Cardiovascular Mortality in a Cohort of Autoworkers: Structural Accelerated Failure Time Models in a Public Health Framework

    PubMed Central

    Picciotto, Sally; Peters, Annette; Eisen, Ellen A.

    2015-01-01

    Occupational exposure to aerosolized particles of oil-based metalworking fluid was recently linked to deaths from ischemic heart disease. The current recommended exposure limits might be insufficient. Studying cardiovascular mortality is challenging because symptoms can induce sicker workers to reduce their exposure, causing healthy-worker survivor bias. G-estimation of accelerated failure time models reduces this bias and permits comparison of multiple exposure interventions. Michigan autoworkers from the United AutoWorkers–General Motors cohort (n = 38,666) were followed from 1941 through 1994. Separate binary variables indicated whether annual exposure exceeded a series of potential limits. Separate g-estimation analyses for each limit yielded the total number of life-years that could have been saved among persons who died from specific cardiovascular causes by enforcing that exposure limit. Banning oil-based fluids would have saved an estimated 4,003 (95% confidence interval: 2,200, 5,807) life-years among those who died of ischemic heart disease. Estimates for cardiovascular disease overall, acute myocardial infarction, and cerebrovascular disease were 3,500 (95% confidence interval: 1,350, 5,651), 2,932 (95% confidence interval: 1,587, 4,277), and 917 (95% confidence interval: ?80, 1,913) life-years, respectively. A limit of 0.01 mg/m3 would have had a similar impact on cerebrovascular disease but one only half as great on ischemic heart disease. Analyses suggest that limiting exposure to metalworking fluids could have saved many life-years lost to cardiovascular diseases in this cohort. PMID:25816818

  15. The reversibility of tributyltin-induced toxicity in vitro as a function of concentration and duration of exposure (C times T)

    SciTech Connect

    Zucker, R.M.; Elstein, K.H. (ManTech Environmental Technology, Inc., Research Triangle Park, NC (United States)); Massaro, E.J. (Environmental Protection Agency, Research Triangle Park, NC (United States))

    1992-02-01

    The toxicity exhibited by murine erythroleukemic cells (MELC) exposed to tributyltin (TBT) is a function of both concentration (C) and duration of exposure (T). At or above a critical C {times} T product value (CPV), exposed MELC exhibit severe, irreversible toxicity: decreased membrane integrity, grossly perturbed cell-cycle distributions, and fixation of the plasma membrane/cytoplasm complex. Below the CPV, exposed cells exhibit retention of carboxyfluorescein (CF) fluorescence (indicative of decreased plasma membrane permeability) and decreased cell proliferation, a result of retardation of progression into, through, and out of the S phase of the cell cycle. However, following washout and recovery, mean CF fluorescence, cell proliferative capacity, and cell-cycle kinetics return to control levels. These results suggest that the toxic changes induced by TBT exposure may be reversible if exposure conditions do not exceed the CPV. To assess whether CPV has been exceeded, a multiparameter flow cytometric analysis of membrane integrity and cell-cycle kinetics is useful.

  16. Application of the constant exposure time technique to transformation experiments with fission neutrons; failure to demonstrate dose-rate dependence

    SciTech Connect

    Balcer-Kubiczek, E.K.; Harrison, G.H.; McCready, W.A.

    1994-12-31

    A direct comparison of the effectiveness of fission neutron at high or several low dose-rates was carried out under identical conditions. Monolayers of exponentially growing C3H/10T1/2 cells were exposed at 37 deg C to reactor-produced neutrons. Survival or transformation induction were studied at five doses from 10(exp 5) to 94 cGy. In low dose-rate irradiations, these doses were protracted over 0.5, 1, 3 or 4.5 h, resulting in 17 different dose-rates. Up to six experiments were performed at each of five exposure times. Concurrently with transformation the authors studied cell proliferation in control versus cells irradiated at 40 cGY acute and a 4.5-h protraction and found no evidence of a shift in the cell cycle distribution among these cells. At a given dose and dose-rate, the effect of dose protraction on survival or transformation was assessed by the dose-rate modifying factor DRMF, defined as the low:high dose-rate effect ratio at the same dose. Survival or transformation induction curves were nearly linear with initial slopes, respectively, of about 6.5 x 10(exp {minus}3) or 6.2 x 10(exp {minus}6) /cGY. Consistent with dose response curves, DRMFs were independent of the dose and dose-rate. The mean values of the dRMF with their uncertainties and 99 deg confidence intervals, based on measurements in individual doses and dose-rates for survival or transformation were, respectively: 1.01 {+-} 0.03, 0.92, 1.09 or 0.98 {+-} 0.04, 0.83, 1.08 indicating a similar precision in determining DRMF for survival or transformation, and no dose or dose-rate influence on these end points.

  17. Measures of activity-based pedestrian exposure to the risk of vehicle-pedestrian collisions: space-time path vs. potential path tree methods.

    PubMed

    Yao, Shenjun; Loo, Becky P Y; Lam, Winnie W Y

    2015-02-01

    Research on the extent to which pedestrians are exposed to road collision risk is important to the improvement of pedestrian safety. As precise geographical information is often difficult and costly to collect, this study proposes a potential path tree method derived from time geography concepts in measuring pedestrian exposure. With negative binomial regression (NBR) and geographically weighted Poisson regression (GWPR) models, the proposed probabilistic two-anchor-point potential path tree (PPT) approach (including the equal and weighted PPT methods) are compared with the deterministic space-time path (STP) method. The results indicate that both STP and PPT methods are useful tools in measuring pedestrian exposure. While the STP method can save much time, the PPT methods outperform the STP method in explaining the underlying vehicle-pedestrian collision pattern. Further research efforts are needed to investigate the influence of walking speed and route choice. PMID:25555021

  18. On the relationship between time-series studies, dynamic population studies, and estimating loss of life due to short-term exposure to environmental risks.

    PubMed Central

    Burnett, Richard T; Dewanji, Anup; Dominici, Francesca; Goldberg, Mark S; Cohen, Aaron; Krewski, Daniel

    2003-01-01

    There is a growing concern that short-term exposure to combustion-related air pollution is associated with increased risk of death. This finding is based largely on time-series studies that estimate associations between daily variations in ambient air pollution concentrations and in the number of nonaccidental deaths within a community. Because these results are not based on cohort or dynamic population designs, where individuals are followed in time, it has been suggested that estimates of effect from these time-series studies cannot be used to determine the amount of life lost because of short-term exposures. We show that results from time-series studies are equivalent to estimates obtained from a dynamic population when each individual's survival experience can be summarized as the daily number of deaths. This occurs when the following conditions are satisfied: a) the environmental covariates vary in time and not between individuals; b) on any given day, the probability of death is small; c) on any given day and after adjusting for known risk factors for mortality such age, sex, smoking habits, and environmental exposures, each subject of the at-risk population has the same probability of death; d) environmental covariates have a common effect on mortality of all members of at-risk population; and e) the averages of individual risk factors, such as smoking habits, over the at-risk population vary smoothly with time. Under these conditions, the association between temporal variation in the environmental covariates and the survival experience of members of the dynamic population can be estimated by regressing the daily number of deaths on the daily value of the environmental covariates, as is done in time-series mortality studies. Issues in extrapolating risk estimates based on time-series studies in one population to estimate the amount of life lost in another population are also discussed. PMID:12842769

  19. Exposure-age constraints on the extent, timing and rate of retreat of the last Irish Sea ice stream

    Microsoft Academic Search

    Danny McCarroll; John O. Stone; Colin K. Ballantyne; James D. Scourse; L. Keith Fifield; David J. A. Evans; John F. Hiemstra

    2010-01-01

    We report 23 cosmogenic isotope exposure ages (10Be and 36Cl) relating to the maximum extent and deglaciation chronology of the Irish Sea Ice Stream (ISIS), which drained the SW sector of the last British–Irish Ice Sheet. These show that the ISIS failed to reach the Preseli Hills of North Pembrokeshire yet extended southwards to impinge on northern Isles of Scilly

  20. Time-dependent exposure dose of hydrogen silsesquioxane when used as a negative electron-beam resist

    E-print Network

    Krchnavek, Robert R.

    is by using a positive resist and depositing metal. Removing the resist and etching the non- metal parts-beam resist Nathaniel Clark, Amy Vanderslice, Robert Grove III, and Robert R. Krchnaveka Rowan University, 201 electron-beam resist for use in nanoimprint lithography. Previous studies show that 1 week long exposure

  1. A real-time regional adaptive exposure method for saving dose-area product in x-ray fluoroscopy

    SciTech Connect

    Burion, Steve; Funk, Tobias [Triple Ring Technologies, Inc., 39655 Eureka Drive, Newark, California 94560 (United States); Speidel, Michael A. [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States)

    2013-05-15

    Purpose: Reduction of radiation dose in x-ray imaging has been recognized as a high priority in the medical community. Here the authors show that a regional adaptive exposure method can reduce dose-area product (DAP) in x-ray fluoroscopy. The authors' method is particularly geared toward providing dose savings for the pediatric population. Methods: The scanning beam digital x-ray system uses a large-area x-ray source with 8000 focal spots in combination with a small photon-counting detector. An imaging frame is obtained by acquiring and reconstructing up to 8000 detector images, each viewing only a small portion of the patient. Regional adaptive exposure was implemented by varying the exposure of the detector images depending on the local opacity of the object. A family of phantoms ranging in size from infant to obese adult was imaged in anteroposterior view with and without adaptive exposure. The DAP delivered to each phantom was measured in each case, and noise performance was compared by generating noise arrays to represent regional noise in the images. These noise arrays were generated by dividing the image into regions of about 6 mm{sup 2}, calculating the relative noise in each region, and placing the relative noise value of each region in a one-dimensional array (noise array) sorted from highest to lowest. Dose-area product savings were calculated as the difference between the ratio of DAP with adaptive exposure to DAP without adaptive exposure. The authors modified this value by a correction factor that matches the noise arrays where relative noise is the highest to report a final dose-area product savings. Results: The average dose-area product saving across the phantom family was (42 {+-} 8)% with the highest dose-area product saving in the child-sized phantom (50%) and the lowest in the phantom mimicking an obese adult (23%). Conclusions: Phantom measurements indicate that a regional adaptive exposure method can produce large DAP savings without compromising the noise performance in the image regions with highest noise.

  2. Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) HP88 for biological control of Rhipicephalus microplus (Acari: Ixodidae): The effect of different exposure times of engorged females to the nematodes

    Microsoft Academic Search

    Caio Márcio de Oliveira Monteiro; Márcia Cristina de Azevedo Prata; Aline Faza; Elder de Paula Simões Batista; Cláudia Dolinski; John Furlong

    The aim of this study was to assess the influence of different exposure times of engorged female the Rhipicephalus microplus to infective juveniles of Heterorhabditis bacteriophora isolate HP88. The engorged females were divided into seven groups (six treatments and one control) of 20 ticks each with statistically similar average weights (p>0.05) and exposed to concentrations of 300 nematodes\\/tick for periods

  3. A method for computing the damage level due to the exposure to an airborne chemical with a time-varying concentration.

    PubMed

    Acquesta, Alejandro D; Sánchez, Erica Yanina; Porta, Andres; Jacovkis, Pablo M

    2011-09-01

    The calculation of damage level due to the exposure to a toxic cloud is usually not included in most popular software, or it is included using techniques that do not take into account the variation in concentration over a period of time. In this work, a method is introduced for calculating the temporal evolution of the potential damage level and to obtain a more precise and descriptive estimation of this level. The proposed goal is: to estimate the maximum and minimum damage level experienced by a population due to the exposure to an airborne chemical with a time-varying concentration; to be able to assess the damage level experienced in a progressive way, as the exposure to the airborne chemical occurs. The method relies on transformations of time-concentration pairs on a continuum of damage level curves based on the available guideline levels, obtaining maximum and minimum approximations of the expected damage level for any exposure duration. Consequently, applying this method to transport model output data and demographic information, damage evolution in relation to time and space can be predicted, as well as its effect on the local population, which enables the determination of threat zones. The comparison between the proposed method and the current (Spanish and ALOHA) ones showed that the former can offer a more precise estimation and a more descriptive approach of the potential damage level. This method can be used by atmospheric dispersion models to compute damage level and graphically display the regions exposed to each guideline level on area maps. PMID:21395635

  4. The influence of incubation time, sample preparation and exposure to oxygen on the quality of the MALDI-TOF MS spectrum of anaerobic bacteria.

    PubMed

    Veloo, A C M; Elgersma, P E; Friedrich, A W; Nagy, E; van Winkelhoff, A J

    2014-12-01

    With matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), bacteria can be identified quickly and reliably. This accounts especially for anaerobic bacteria. Because growth rate and oxygen sensitivity differ among anaerobic bacteria, we aimed to study the influence of incubation time, exposure to oxygen and sample preparation on the quality of the spectrum using the Bruker system. Also, reproducibility and inter-examiner variability were determined. Twenty-six anaerobic species, representing 17 genera, were selected based on gram-stain characteristics, growth rate and colony morphology. Inter-examiner variation showed that experience in the preparation of the targets can be a significant variable. The influence of incubation time was determined between 24 and 96 h of incubation. Reliable species identification was obtained after 48 h of incubation for gram-negative anaerobes and after 72 h for gram-positive anaerobes. Exposure of the cultures to oxygen did not influence the results of the MALDI-TOF MS identifications of all tested gram-positive species. Fusobacterium necrophorum and Prevotella intermedia could not be identified after >24 h and 48 h of exposure to oxygen, respectively. Other tested gram-negative bacteria could be identified after 48 h of exposure to oxygen. Most of the tested species could be identified using the direct spotting method. Bifidobacterium longum and Finegoldia magna needed on-target extraction with 70% formic acid in order to obtain reliable species identification and Peptoniphilus ivorii a full extraction. Spectrum quality was influenced by the amount of bacteria spotted on the target, the homogeneity of the smear and the experience of the examiner. PMID:25039504

  5. A comparison of physiological changes in carp, Cyprinus carpio, induced by several pollutants at sublethal concentrations. I. The dependency on exposure time.

    PubMed

    Gluth, G; Hanke, W

    1985-04-01

    Carp were exposed to 10 different pollutants at sublethal concentrations for 6, 24, or 72 hr. Blood, liver, and white muscle samples were taken after the exposure time together with samples of control handled fish. Serum concentrations of glucose, cortisol protein, and cholesterol were determined. Similarly, the liver and muscle glycogen contents were measured. The effects of the following pollutants were examined: aldrin (100 micrograms/liter), atrazine (100 micrograms/liter), DDT (50 micrograms/liter), dieldrin (20 micrograms/liter), endrin (2 micrograms/liter), hexachlorbenzene (100 micrograms/liter), lindane (100 micrograms/liter), methanol (1 ml/liter), 4-N-phenol (100 micrograms/liter), toluene (100 microliters/liter). The rises in serum glucose and cortisol were the most frequent changes occurring after exposure to the pollutants. A decline in plasma protein and cholesterol content was also often observed. Liver glycogen concentration increased first in most cases and was reduced after longer exposure. Muscle glycogen was affected differently, sometimes reduced by exposure to the pollutants. The experimental design allows for the gradual increase in toxicity of the pollutants used regarding the applied concentrations. Furthermore, the aim of the paper is to evaluate the tests for proof of toxicity of those chemicals. The determination of serum glucose and cortisol levels can be proposed as mostly useful. The clearest changes in all parameters were found after treatment with 100 micrograms/liter atrazine and 50 micrograms/liter DDT. When serum glucose and cortisol concentrations were quickly elevated, signs for exhaustion could be seen after 72 hr of exposure. PMID:3987597

  6. Time trends in incidence of cutaneous melanoma by detailed anatomical location and patterns of ultraviolet radiation exposure: a retrospective population-based study.

    PubMed

    Gordon, Daniela; Gillgren, Peter; Eloranta, Sandra; Olsson, Henrik; Gordon, Max; Hansson, Johan; Smedby, Karin E

    2015-08-01

    Given the wide public health implications of the melanoma epidemic, ultraviolet radiation (UVR) exposure patterns contributing to cutaneous melanoma development should be clearly identified. To describe time trends of anatomic sites of melanoma using a UVR exposure model based on clothing and sun habits, we reviewed the medical records of all patients diagnosed with primary invasive melanoma or melanoma in situ (MIS) during the years 1977-78, 1983-84, 1989-90, 1995-96, and 2000-01 (n=3058) in one healthcare region of Sweden. Age-standardized incidence rates and relative risks (RRs) of melanoma by calendar period were estimated for intermittent and chronic UVR exposure sites. From 1977-78 to 2000-01, the incidence rates of all melanomas at intermittent UVR exposure sites increased both among men (7.8-16.5/10 person-years) and among women (7.6-14.6/10 person-years), with a sex-adjusted and age-adjusted RR of 2.1 [95% confidence interval (CI) 1.8-2.4, Ptrend<0.0001]. This increase was evident for both invasive melanoma and MIS. Melanoma at chronic sites increased among men from 1.7 to 2.3/10 person-years, and among women from 1.4 to 1.8/10 person-years, with a corresponding adjusted RR of 1.4 (95% CI 1.0-1.9, Ptrend=0.01), driven primarily by MIS. For melanomas at intermittent UVR exposure sites, the male sex was positively associated with central (core) areas (chest, back, neck, shoulders, thighs; RR 1.7, 95% CI 1.5-1.9), but negatively associated with peripheral areas (lateral arms, lower legs, dorsum of feet; RR 0.3, 95% CI 0.3-0.4), compared with the female sex. Sex-specific intermittent UVR exposure patterns drove the observed increase in melanoma incidence, whereas chronic UVR exposure contributed less. PMID:26050147

  7. Exposure levels due to WLAN devices in indoor environments corrected by a time-amplitude factor of distribution of the quasi-stochastic signals.

    PubMed

    Miclaus, Simona; Bechet, Paul; Stratakis, Dimitrios

    2014-12-01

    With the development of radiofrequency technology, radiating quasi-stochastic signals like the wireless local area networks (WLAN), a proper procedure of exposure level assessment is needed. No standardised procedure exists at the moment. While channel power measurement proved to overestimate the field strength, weighting techniques were proposed. The paper compares the exposure levels determined by three different procedures, two of them correcting the field level by weighting. Twenty-three experimental cases of WLAN traffic load are analysed in an indoor environment in controlled conditions. The results show the differences obtained when the duty cycle (DC) method is applied comparatively with the application of weighting based on an amplitude-time correction. Significant exposure level reductions of 52.6-79.2 % from the field determined by frequency domain method and of 36.5-72.8 % from the field determined by the DC weighting method were obtained by time-amplitude method. Specificities of weighting factors probability density functions were investigated and regression analysis was applied for a detailed characterisation of this procedure. PMID:24591729

  8. The effect of short-time microwave exposures on Escherichia coli O157:H7 inoculated onto chicken meat portions and whole chickens.

    PubMed

    Apostolou, I; Papadopoulou, C; Levidiotou, S; Ioannides, K

    2005-05-01

    Small portions of fresh chicken breasts weighting 20 g each and fresh whole chickens, weighting on average 1310 g each, were inoculated with Escherichia coli O157:H7 (10(5)-10(6) cfu/g) and cooked, using two different domestic microwave ovens at full power. The chicken portions were heated for 5, 10, 15, 20, 25, 30, and 35 s and the whole chickens for 22 min. Following exposures, viable counts and temperature measurements were performed. Although the chicken breast portions looked well-cooked after 30 s of MW heating at a mean end-point surface temperature of 69.8 degrees C, a mean concentration of 83 cfu/g E. coli O157:H7 cells was recovered. Elimination of E. coli O157:H7 cells occurred only after 35 s of MW exposure at 73.7 degrees C. When whole chickens were thoroughly cooked by MW heating, the final subsurface temperatures, measured in the thighs and wings, ranged from 60.2 degrees C to 92 degrees C and viable cells of E. coli O157:H7 were recovered from all samples of whole chicken. The results indicate that short time exposures of chicken portions to microwave heating do not eliminate E. coli O157:H7. PMID:15878411

  9. Comparison of Cell Viability and Embryoid Body Size of Two Embryonic Stem Cell Lines After Different Exposure Times to Bone Morphogenetic Protein 4

    PubMed Central

    Zarei Fard, Nehleh; Talaei-Khozani, Tahereh; Bahmanpour, Soghra; Esmaeilpour, Tahereh

    2015-01-01

    Background Activation of bone morphogenetic protein 4 (BMP4) signaling pathway in embryonic stem (ES) cells plays an important role in controlling cell proliferation, differentiation, and apoptosis. Adverse effects of BMP4 occur in a time dependent manner; however, little is known about the effect of different time exposure of this growth factor on cell number in culture media. In this study, we investigated the role of two different exposure times to BMP4 in cell viability, embryoid body (EB), size, and cavitation of ES cells. Methods Embryonic stem cells (R1 and B1 lines) were released from the feeder cell layers and were cultured using EBs protocol by using the hanging drop method and monolayer culture system. The cells were cultured for 5 days with 100 ng/mL BMP4 from the beginning (++BMP4) or after 48 h (+BMP4) of culture and their cell number were counted by trypan blue staining. The data were analyzed using non-parametric two-tailed Mann-Whitney test. P<0.05 was considered as significant. Results In EB culture protocol, cell number significantly decreased in +BMP4 culture condition with greater cavity size compared to the ++BMP4 condition at day 5 (P=0.009). In contrast, in monolayer culture system, there was no significant difference in the cell number between all groups (P=0.91). Conclusion The results suggest that short-term exposure of BMP4 is required to promote cavitation in EBs according to lower cell number in +BMP4 condition. Different cell lines showed different behavior in cavitation formation. PMID:25821290

  10. Study on hydrofluoric acid-based clad etching and chemical sensing characteristics of fiber Bragg gratings of different reflectivity fabricated under different UV exposure times

    NASA Astrophysics Data System (ADS)

    Kumar, Jitendra; Mahakud, Ramakant; Prakash, Om; Dixit, Sudhir Kumar

    2013-05-01

    An experimental study on hydrofluoric acid (HF)-based clad etching and chemical sensing characteristics of fiber Bragg gratings (FBG) of different reflectivity fabricated under different UV (255 nm) exposure times is presented. Two FBGs of reflectivity 11% and 93% were inscribed by phase mask-based exposition of the photosensitive fibers by a 5.5 kHz repetition rate of 255 nm UV pulses for 15 s and 10 min, respectively. These two FBGs, employed in an HF-based clad etching experiment, revealed a much higher etching rate of 2.03 ?m/min for the grating of reflectivity 11% as compared to 1.69 ?m/min for the grating of reflectivity 93%. The performance of these etched FBGs were also studied for refractive index sensing of the chemicals ethanol and ethylene glycol under different fiber etching times, hence of different residual cladding diameter. It was observed that the same refractive index sensitivity for both the chemicals could be achieved under smaller etching time, i.e., larger residual cladding diameter, for the FBG with lower reflectivity. This differentiating behavior of FBGs under etching and sensing may be linked to the different degree of densification in fused silica fiber cladding under different UV fluence exposures.

  11. Poor, Unsafe, and Overweight: The Role of Feeling Unsafe at School in Mediating the Association Among Poverty Exposure, Youth Screen Time, Physical Activity, and Weight Status.

    PubMed

    Côté-Lussier, Carolyn; Fitzpatrick, Caroline; Séguin, Louise; Barnett, Tracie A

    2015-07-01

    This study applied socioecological and cumulative risk exposure frameworks to test the hypotheses that 1) the experience of poverty is associated with feeling less safe at school, and 2) feeling less safe is associated with engaging in poorer weight-related behaviors, as well as an increased probability of being overweight or obese. Data were from the ongoing Québec Longitudinal Study of Child Development, initiated in 1998 with a population-based cohort of 2,120 Québec (Canada) infants 5 months of age and their parent or primary caregiver. Measures of youths' (age, 13 years) self-reported feelings of safety, screen time, physical activity, and objectively assessed not overweight/obese (70%), overweight (22%), and obese (8%) weight status were collected in 2011. Family poverty trajectory from birth was assessed by using latent growth modeling. As hypothesized, exposure to poverty was associated with feeling less safe at school and, in turn, with an increased probability of being overweight or obese. The association was most pronounced for youths who experienced chronic poverty. Compared with youths who experienced no poverty and felt unsafe, those who experienced chronic poverty and felt unsafe were nearly 18% more likely to be obese (9.2% vs. 11.2%). Although feeling unsafe was associated with screen time, screen time did not predict weight status. PMID:25921649

  12. Individual breast milk consumption and exposure to PCBs and PCDD/Fs in Hungarian infants: a time-course analysis of the first three months of lactation.

    PubMed

    Vigh, Éva; Colombo, Andrea; Benfenati, Emilio; Håkansson, Helen; Berglund, Marika; Bódis, József; Garai, János

    2013-04-01

    Polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are persistent, bioaccumulative and toxic chemicals. These compounds are transferred to breast milk, therefore breastfed infants are at risk of being exposed to considerable amounts of PCBs and PCDD/Fs during this sensitive age. In the present study individual breast milk samples were collected at three time points (days 5, 12 and 84 postpartum) from 22 mothers who delivered their infants during 2007 in Baranya County, Hungary. Breast milk samples were analyzed for 17 PCDD/Fs, 12 dioxin-like (DL) PCBs and 7 non-dioxin-like (NDL) PCBs using high-resolution gas chromatography/high-resolution mass spectrometry. Each infant's daily breast milk consumptions have been measured biweekly over three months. The concentration of several PCB and PCDD congeners in breast milk decreased significantly during lactation, with a main decline between days 5 and 12. The total toxic equivalent (TEQ) concentrations, derived from PCDD/Fs and DL-PCBs, were 3.17±1.72, 2.70±1.57 and 2.41±1.47 pg TEQ/g fat at the three time points, respectively. The corresponding NDL-PCB concentrations were 33.5±29.2, 27.4±20.6 and 26.9±24.8 ng/g fat, respectively. The results highlight the importance of timing of breast milk sampling for consistent exposure assessment estimation. Levels of pollutants in Hungarian breast milk samples were at the lower concentration range when data from Europe are considered. This is the first study in Hungary where each infant's daily intakes of PCBs and PCDD/Fs via breast milk have been measured. The daily intakes of PCDD/Fs and DL-PCBs via breastfeeding per kg body weight were 11.79±6.42, 16.54±13.02 and 11.59±7.70 pg TEQ/kg bw on days 5, 12 and 84, respectively. The exposure was the highest on day 12 but at all three time points each infants' daily exposure to PCDD/Fs and DL-PCBs via breastfeeding exceeded the tolerable daily intake (TDI) of 2 pg TEQ/kg bw per day. These levels are still lower than corresponding levels recently measured in many European countries. Whether the milk-derived POP exposure levels of infants reported here constitute any health risk that may manifest later in life awaits further scrutiny. PMID:23435065

  13. MODEL DEVELOPMENT - EXPOSURE MODELS

    EPA Science Inventory

    Humans are exposed to mixtures of chemicals from multiple pathways and routes. These exposures may result from a single event or may accumulate over time if multiple exposure events occur. The traditional approach of assessing risk from a single chemical and a single route of e...

  14. Experimental study on the survival of the water hyacinth (Eichhornia crassipes (Mart.) Solms--Pontederiaceae) under different oil doses and times of exposure.

    PubMed

    Lopes, Aline; Piedade, Maria Teresa Fernandez

    2014-12-01

    In the last decades, petroleum activities have increased in the Brazilian Amazon where there is oil exploration on the Urucu River, a tributary of the Amazon River, about 600 km from the city of Manaus. Particularly, transportation via the Amazon River to reach the oil refinery in Manaus may compromise the integrity of the large floodplains that flank hundreds of kilometers of this major river. In the Amazon floodplains, plant growth and nutrient cycling are related to the flood pulse. When oil spills occur, floating oil on the water surface is dispersed through wind and wave action in the littoral region, thus affecting the vegetation of terrestrial and aquatic environments. If pollutants enter the system, they are absorbed by plants and distributed in the food chain via plant consumption, mortality, and decomposition. The effect of oil on the growth and survival of vegetation in these environments is virtually unknown. The water hyacinth [Eichhornia crassipes (Mart.) Solms] has a pantropical distribution but is native to the Amazon, often growing in high-density populations in the floodplains where it plays an important role as shelter and food source for aquatic and terrestrial biota. The species is well known for its high capacity to absorb and tolerate high levels of heavy metal ions. To study the survival and response of water hyacinth under six different oil doses, ranging from 0 to 150 ml l(-1), and five exposure times (1, 5, 10, 15, and 20 days), young individuals distributed in a completely randomized design experiment composed of vessels with a single individual each were followed over a 50-day period (30-day acclimatization, 20 days under oil treatments). Growth parameters, biomass, visual changes in the plants, and pH were recorded at 1, 5, 10, 15, and 20 days. Increasing the time of oil exposure caused a decrease in biomass, ratio of live/dead biomass and length of leaves, and an increase in the number of dead leaves. Dose of oil and time of exposure are the most important factors controlling the effects of petroleum hydrocarbons on E. crassipes. Although the species is able to survive exposure to a moderate dose of oil, below 75 ml l(-1) for only 5 days, severe alterations in plant growth and high mortality were observed. Therefore, we conclude that Urucu oil heavily affects E. crassipes despite its known resistance to many pollutants. PMID:25017871

  15. Time-dependent alterations in growth, photosynthetic pigments and enzymatic defense systems of submerged Ceratophyllum demersum during exposure to the cyanobacterial neurotoxin anatoxin-a.

    PubMed

    Ha, Mi-Hee; Pflugmacher, Stephan

    2013-08-15

    Recently, aquatic macrophytes have been considered as promising tools for eco-friendly water management with a low running cost. However, only little information is available thus far regarding the metabolic capacity of macrophytes for coping with cyanobacterial toxins (cyanotoxins) in the aquatic environment. Cyanotoxins have become emerging contaminants of great concern due to the high proliferation of cyanobacteria (cyanobacterial bloom) accelerated by eutrophication and climate change. Anatoxin-a, one of the common and major cyanotoxins, is suggested as a high priority water pollutant for regulatory consideration owing to its notoriously rapid mode of action as a neurotoxin. In this study, the time-course metabolic regulation of the submerged macrophyte Ceratophyllum demersum (C. demersum) was investigated during exposure to anatoxin-a at an environmentally relevant concentration (15 ?g/L). Biotransformation and antioxidative systems in C. demersum responded positively to anatoxin-a through the promoted synthesis of most of the involved enzymes within 8h. Maximum enzyme activities were exhibited after 24 or 48 h of exposure to anatoxin-a. However, an apparent decline in enzyme activities was also observed at longer exposure duration (168 and 336 h) in company with high steady-state levels of cell internal H?O?, which showed its highest level after 48 h. Meanwhile, irreversible inhibitory influence on chlorophyll content (vitality) was noticed, whereas the ratio of carotenoids to total chlorophyll was increased with the increase in exposure duration. Consequently, the reduction in growth (biomass) of C. demersum was observed in sub-chronic exposure to anatoxin-a (8 weeks). Overall results clearly indicate, on the one hand, that anatoxin-a causes negative allelopathic effects on the macrophyte by inducing oxidative stress. On the other hand, the macrophyte might have interactions with anatoxin-a, based on the prompt reaction of its enzymatic defense systems to the toxin. The result obtained from the present study could contribute to the improvement of basic knowledge about the ecological impact of anatoxin-a and the environmental fate of the toxin in the aquatic environment. PMID:23685387

  16. Timing of late Pleistocene glaciation in Mongolia: Surface exposure dating reveals a differentiated pattern of glacial forcing

    NASA Astrophysics Data System (ADS)

    Pötsch, Steffen; Rother, Henrik; Lorenz, Sebastian; Walther, Michael; Lehmkuhl, Frank

    2015-04-01

    The focus of this study is on the geochronological and paleoclimatic characterization of Pleistocene glaciation in central (Khangai Mountains) and western (Turgen Mountains, Mongolian Altai) Mongolia. These two mountain ranges form a 700 km long SE-NW transect through Mongolia and allow assumptions of the temporal and causal dynamics of regional glaciation and their correlation to other mountain glacier records from Central and High Asia. In order to evaluate the Pleistocene glaciations in Mongolia we undertook geomorphological mapping and cosmogenic radionuclide (CRN) surface exposure dating (10Be) in four valley systems located in the Khangai Mountains and Turgen Mountains. In total 46 glacial boulders and roche moutonnées were sampled, prepared and AMS measured to determine their 10Be surface exposure ages. Of these, 26 samples were obtained from the Khangai Mountains (three separate moraine sequences) and 20 samples were taken from the Turgen Mountains (one moraine sequence). Our results give evidence of major ice advances during early MIS-4 (74?71 ka) and MIS-2 (25?20 and 18? 17 ka) in both mountain ranges. However, in the Khangai Mountains of central Mongolia very significant ice advances also occurred during MIS-3 (37?32 ka), which exceeded the ice limits set during the MIS-2 glaciation. These results show that climatic conditions during phases of insolation minima characterized by extremely cold and dry conditions (MIS-4 and MIS-2) produced a favorable setting for major ice expansion in Mongolia. Yet, glacial accumulation in the Khangai Mountains also increased substantially in response to the cool-wet conditions of MIS-3, associated with a possibly greater-than-today input from winter precipitation. These records indicate that in addition to the thermally induced glaciations of MIS-4 and MIS-2, variations in atmospheric moisture supply are also capable of triggering large ice advances as observed during MIS-3. Taken together, this suggests that the role of atmospheric circulation and its significance for controlling regional precipitation results in a more differentiated pattern of late Pleistocene glaciation in Mongolia than previously recognized. Compared to other glacial records from High Asia, the observed patterns of past glaciations in Mongolia show similar results (i.e. ice maxima during interstadial wet phases) compared to monsoon influenced regions in southern Central Asia and NE-Tibet, while major expansion during insolation minima (MIS-4 and MIS-2) are more in tune with glacier responses known from western Central Asia and Siberia.

  17. Adaptation of natural microbial communities to degradation of xenobiotic compounds: effects of concentration, exposure time, inoculum, and chemical structure

    SciTech Connect

    Spain, U.C. (U.S. Environmental Protection Agency, Gulf Breeze, FL); Van Veld, P.A.

    1983-02-01

    Adaptation of microbial communities to faster degradation of xenobiotic compounds after exposure to the compound was studied in ecocores. Radiolabeled test compounds were added to cores that contained natural water and sediment. Adaptation was detected by comparing mineralization rates or disappearance of a parent compound in preexposed and unexposed cores. Microbial communities in preexposed cores from a number of freshwater sampling sites adapted to degrade p-nitrophenol faster; communities from estuarine or marine sites did not show any increase in rates of degradation as a result of preexposure. Adaptation was maximal after 2 weeks and was not detectable after 6 weeks. A threshold concentration of 10 ppb (10 ng/ml) was observed; below this concentration no adaptation was detected. With concentrations of 20 to 100 ppb (20 to 100 ng/ml), the biodegradation rates in preexposed cores were much higher than the rates in control cores and were proportional to the concentration of the test compound. In addition, trifluralin, 2,4-dichlorophenoxyacetic acid, and p-cresol were tested to determine whether preexposure affected subsequent biodegradation. Microbial communities did not adapt to trifluralin. Adaptation to 2,4-dichlorophenoxyacetic acid was similar to adaptation to nitrophenol. p-Cresol was mineralized rapidly in both preexposed and unexposed communities.

  18. Persuasion Via Mere Exposure

    ERIC Educational Resources Information Center

    Tucker, Raymond K.; Ware, Paul D.

    1971-01-01

    Describes an experiment which sought to effect persuasion by merely exposing subjects to the name of a stimulus object for a specified number of times. Through illustration, explains the theoretical basis and methodology employed in a mere exposure experiment. (Author)

  19. The Long-Term Impact of the MEMA kwa Vijana Adolescent Sexual and Reproductive Health Intervention: Effect of Dose and Time since Intervention Exposure

    PubMed Central

    Doyle, Aoife M.; Weiss, Helen A.; Maganja, Kaballa; Kapiga, Saidi; McCormack, Sheena; Watson-Jones, Deborah; Changalucha, John; Hayes, Richard J.; Ross, David A.

    2011-01-01

    Background Despite recent decreases in HIV incidence in many sub-Saharan African countries, there is little evidence that specific behavioural interventions have led to a reduction in HIV among young people. Further and wider-scale decreases in HIV require better understanding of when behaviour change occurs and why. The MEMA kwa Vijana adolescent sexual and reproductive health intervention has been implemented in rural Mwanza, Tanzania since 1999. A long-term evaluation in 2007/8 found that the intervention improved knowledge, attitudes to sex and some reported risk behaviours, but not HIV or HSV2 prevalence. The aim of this paper was to assess the differential impact of the intervention according to gender, age, marital status, number of years of exposure and time since last exposure to the intervention. Methods In 2007, a cross-sectional survey was conducted in the 20 trial communities among 13,814 young people (15–30 yrs) who had attended intervention or comparison schools between 1999 and 2002. Outcomes for which the intervention had an impact in 2001 or 2007 were included in this subgroup analysis. Data were analysed using cluster-level methods for stratified cluster-randomised trials, using interaction tests to determine if intervention impact differed by subgroup. Results Taking into account multiplicity of testing, concurrence with a priori hypotheses and consistency within the results no strong effect-modifiers emerged. Impact on pregnancy knowledge and reported attitudes to sex increased with years of exposure to high-quality intervention. Conclusions The desirable long-term impact of the MEMA kwa Vijana intervention did not vary greatly according to the subgroups examined. This suggests that the intervention can have an impact on a broad cross-section of young people in rural Mwanza. Trial registration ClinicalTrials.gov NCT00248469 PMID:21931861

  20. Choline supplementation attenuates learning deficits associated with neonatal alcohol exposure in the rat: Effects of varying the timing of choline administration

    PubMed Central

    Ryan, S. Hunter; Williams, Jennifer K.; Thomas, Jennifer D.

    2008-01-01

    Despite the harmful effects of fetal alcohol exposure, some pregnant women continue to drink alcohol. Thus, it is imperative to pursue safe, effective treatments for children with fetal alcohol spectrum disorders. Using an animal model, our laboratory has demonstrated that choline, an essential nutrient, effectively reduces the severity of some fetal alcohol effects, even when administered after the ethanol insult is complete. The present study investigated whether there is a critical developmental period when choline is most effective in attenuating ethanol’s teratogenic effects. Sprague-Dawley rats were exposed to 5.25 g/kg/day ethanol during the third trimester equivalent brain growth spurt (postnatal days (PD) 4–9) via intubation. A non-intubation control group and a sham intubation control group were included. Following ethanol exposure, pups received subcutaneous injections of saline vehicle or choline chloride (100 mg/kg/day) from PD 11–20, PD 21–30, or PD 11–30. Beginning on PD 45, subjects were tested on a Morris water maze spatial learning task. Performance of both the ethanol-exposed group that did not receive choline and the ethanol-exposed group treated with choline from PD 21–30 was significantly impaired compared to controls during acquisition of the Morris water maze task. Performance of ethanol-exposed groups treated with choline from PD 11–20 or PD 11–30 was intermediate, not differing significantly from any other groups. However, during the probe trial, ethanol exposure produced significant deficits in spatial memory which were mitigated by all choline treatments, regardless of the timing of administration. These findings suggest that choline’s therapeutic window may be very large, or spans across the two developmental periods examined in this study. Importantly, these findings indicate that choline supplementation may effectively reduce some alcohol-related learning impairments, even when administered in later childhood. PMID:18786517

  1. A urinary metabolomics study of rats after the exposure to acrylamide by ultra performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry.

    PubMed

    Wang, Sheng-Yuan; Wang, Yue; Jin, Xin-Wen; Zhang, Yan; Chen, Jia-Shu; Ma, Wei-Wei; Wu, Yong-Hui; Wang, De-Cai

    2015-04-01

    Acrylamide (ACR) is known to induce neurotoxicity in humans and occupational exposure to ACR has an effect on human health. Since some animal experiments indicate the metabolic change caused by the ACR based on the metabolomics, increasing concern is the change of metabolite profiles by the low-dose ACR. In the present study, a low-dose of ACR (18 mg kg(-1)) was administered to male Wistar rats for 40 days. Ultra performance liquid chromatography/time of flight mass spectrometry (UPLC-Q-TOF MS) was used to examine urine samples from ACR-dosed and control animals. Multiple statistical analyses with principal component analysis (PCA) were used to investigate metabolite profile changes in urine samples, and to screen for potential neurotoxicity biomarkers. PCA showed differences between the ACR-dosed and control groups 20 days after the start of dosing; a bigger separation between the two groups was seen after dosing for 40 days. Levels of 4-guanidinobutanoic acid and 2-oxoarginine were significantly higher in urine from the ACR-dosed group than in urine from the control group after 10 days (p < 0.05). Receiver operator characteristic (ROC) curve analysis suggested that 4-guanidinobutanoic acid and 2-oxoarginine were the major metabolites. Our results suggest that high levels of 4-guanidinobutanoic acid and 2-oxoarginine may be related to ACR neurotoxicity. These metabolites could, therefore, act as sensitive biomarkers for ACR exposure and be useful for investigating toxic mechanisms. They may also provide a scientific foundation for assessing the effects of chronic low-dose ACR exposure on human health. PMID:25687561

  2. HUMAN EXPOSURE ASSESSMENT USING IMMUNOASSAY

    EPA Science Inventory

    The National Exposure Research Laboratory-Las Vegas is developing analytical methods for human exposure assessment studies. Critical exposure studies generate a large number of samples which must be analyzed in a reliable, cost-effective and timely manner. TCP (3,5,6-trichlor...

  3. Diverging Experiences during Out-of-School Time: The Race Gap in Exposure to After-School Programs

    ERIC Educational Resources Information Center

    Hynes, Kathryn; Sanders, Felicia

    2011-01-01

    There is considerable interest in identifying ways to close the Black-White achievement gap. This study examines race differences in children's participation in after-school programs, an out-of-school time experience that may influence children's achievement. Using nationally representative data spanning 1995-2005, the authors find that African…

  4. Short-time exposure to mono-n-butyl phthalate (MBP)-induced oxidative stress associated with DNA damage and the atrophy of the testis in pubertal rats.

    PubMed

    Shono, Takeshi; Taguchi, Tomoaki

    2014-02-01

    Phthalates are widely used as plasticizer in various consumer domestic products and are known to disturb the male reproductive function in rodents. This study investigated the involvement of oxidative stress and the atrophy of the testes in pubertal rats exposed to mono-n-butyl phthalate (MBP). Four-week-old pubertal male rats were separated into three groups. In group I, 21 rats were fed rat chow containing 2 % MBP for 3 days. In group II, 21 rats were fed rat chow containing 2 % MBP for 3 days and antioxidant vitamins C (250 mg/kg/day) and E (50 mg/kg/day) were injected daily. In group III, 21 rats were fed standard rat chow and used as controls. After 3 days, each testis was weighed and the germ cell development was evaluated using the Johnsen score. The urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were measured as a biological marker of oxidative DNA damage. The mean testis weight was significantly lower for group I than groups II or III (p?time exposure to MBP may therefore induce oxidative DNA damage in rat testes, while antioxidant vitamins administered during exposure may protect against this stress. PMID:24310901

  5. Effects of Wi-Fi (2.45 GHz) Exposure on Apoptosis, Sperm Parameters and Testicular Histomorphometry in Rats: A Time Course Study

    PubMed Central

    Shokri, Saeed; Soltani, Aiob; Kazemi, Mahsa; Sardari, Dariush; Mofrad, Farshid Babapoor

    2015-01-01

    Objective In today’s world, 2.45-GHz radio-frequency radiation (RFR) from industrial, scientific, medical, military and domestic applications is the main part of indoor-outdoor electromagnetic field exposure. Long-term effects of 2.45-GHz Wi-Fi radiation on male reproductive system was not known completely. Therefore, this study aimed to investigate the major cause of male infertility during short- and long-term exposure of Wi-Fi radiation. Materials and Methods This is an animal experimental study, which was conducted in the Department of Anatomical Sciences, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, IRAN, from June to August 2014. Three-month-old male Wistar rats (n=27) were exposed to the 2.45 GHz radiation in a chamber with two Wi-Fi antennas on opposite walls. Animals were divided into the three following groups: I. control group (n=9) including healthy animals without any exposure to the antenna, II. 1-hour group (n=9) exposed to the 2.45 GHz Wi-Fi radiation for 1 hour per day during two months and III.7-hour group (n=9) exposed to the 2.45 GHz Wi-Fi radiation for 7 hours per day during 2 months. Sperm parameters, caspase-3 concentrations, histomorphometric changes of testis in addition to the apoptotic indexes were evaluated in the exposed and control animals. Results Both 1-hour and 7-hour groups showed a decrease in sperm parameters in a time dependent pattern. In parallel, the number of apoptosis-positive cells and caspase-3 activity increased in the seminiferous tubules of exposed rats. The seminal vesicle weight reduced significantly in both1-hour or 7-hour groups in comparison to the control group. Conclusion Regarding to the progressive privilege of 2.45 GHz wireless networks in our environment, we concluded that there should be a major concern regarding the timedependent exposure of whole-body to the higher frequencies of Wi-Fi networks existing in the vicinity of our living places. PMID:26199911

  6. Advanced Exposure Metrics For Chemical Risk Analysis: Systems Biology and 'Omic-based Biomarkers for Exposure Reconstruction

    EPA Science Inventory

    Direct measurement of human exposure to environmental contaminants in real time (when the exposure is actually occurring) is rare and difficult to obtain. This frustrates both exposure assessments and investigations into the linkage between chemical exposure and human disease. ...

  7. Assessment of physical education time and after-school outdoor time in elementary and middle school students in south Mexico City: the dilemma between physical fitness and the adverse health effects of outdoor pollutant exposure.

    PubMed

    Villarreal-Calderón, Anna; Acuña, Hilda; Villarreal-Calderón, Jessica; Garduño, Mónica; Henríquez-Roldán, Carlos F; Calderón-Garcidueñas, Lilian; Valencia-Salazar, Gildardo

    2002-01-01

    Strategies to promote lifelong physical activity among children are needed to stem the adverse health consequences of inactivity. However, the health effects in growing children of long-term exposure to a polluted atmosphere are of deep concern. The atmosphere of south Mexico City (SMC) is characterized by a complex mixture of air pollutants, including ozone, particulate matter, and aldehydes. Radiological evidence suggests that small-airway disease could be present in clinically healthy, tobacco unexposed SMC children. The aim of this study was to assess, by means of a self-reported questionnaire, the physical education class times, daily outdoor after-school exposure time, and tobacco exposure in students attending public elementary and middle schools in SMC. Additionally, the time each student spent viewing television was assessed, and the authors measured each student's weight and height to determine body mass index (BMI, weight in kg divided by height in m2). The survey included 1,159 students in grades 7-9. The authors identified 2 critical periods of outdoor exposure in SMC children that coincided with significant concentrations of both ozone and particulate matter with diameters less than 10 micrometers (PM10): during school time after 11:00 A.M. and in the after-school outdoor activity period, usually extending from 1:00 P.M. to 6:00 P.M. Thirty-two percent of elementary and 61% of middle school students have physical education classes after 11:00 A.M. Students in SMC spend an average of 19.6 hr/wk outdoors in the after-school period, during which time they are engaged in light to moderate physical activities. Half of the students are exposed to tobacco smoke at home, and 7% of middle school students smoke. On the basis of BMI, 60% of students were classified as undernourished, overweight, or obese. No correlations were found between BMI and time spent viewing TV, time outdoors (on weekdays and weekends), or exposure to environmental tobacco smoke. Children and adolescents in SMC are participating in physical activities that enhance multiple components of health-related fitness. However, their activities occur outdoors, where they are exposed to high concentrations of air pollutants throughout the year. The authors believe that SMC children and adolescents must be educated, through both the school and health systems, regarding ways to obtain the necessary exercise while protecting themselves from the high concentrations of pollutants. Individuals should instruct and encourage young people to be involved in lifetime fitness activities and to eat balanced diets, if the goal is to control health-care costs, reduce disease incidence, and improve the overall quality of life of the Mexico City population. PMID:12641189

  8. Effects of progestagen exposure duration on estrus synchronization and conception rates of crossbreed ewes undergoing fixed time artificial insemination

    PubMed Central

    Blaschi, Wanessa; Lunardelli, Paula A.; Marinho, Luciana S.R.; Max, Marilu C.; Santos, Gustavo M.G.; Silva-Santos, Katia C.; Melo-Sterza, Fabiana A.; Baldassarre, Hernan; Rigo, Thales R.

    2014-01-01

    Synchronization of estrus and ovulation are of paramount importance in modern livestock improvement programs. These methods are critical for assisted reproduction technologies, including artificial insemination and embryo transfer, that can increase productivity. In the current study, subcutaneous implants containing norgestomet were placed for long (14 days), medium (9 days), and short (5 days) periods of time in 70 crossbred ewes undergoing fixed-time artificial insemination. The resulting effects on estrus synchronization and conception rates were subsequently evaluated. Among the synchronized ewes, 85.7% (60/70) underwent estrus over a period of 72 h after progestagen treatment ceased. The shortest mean interval between withdrawal of the device and onset of estrus (34.2 ± 8.9 h) was observed in the G14 days of P4 group (p < 0.05). The conception rate of the G14 days of P4 group was statistically higher than that of the other groups (83.3% vs. 60.9% vs. 47.8%; p < 0.05). In conclusion, 14 days of norgestomet treatment produced higher conception rates and a greater number of pregnancies at the beginning of the breeding season. PMID:24962414

  9. Heavy equipment maintenance exposure assessment: using a time-activity model to estimate surrogate values for replacement of missing data.

    PubMed

    Boelter, Fred W; Spencer, John W; Simmons, Catherine E

    2007-07-01

    This study on four pieces of heavy construction equipment was conducted to determine the concentration of airborne asbestos fibers during in-frame maintenance and repair activities, which included aggressive techniques that resulted in visible dust from work involving friction products and gaskets. Despite execution of a carefully planned sampling strategy, approximately 10% (47) of the samples collected could not be analyzed due to overloading or filter damage. To include the overloaded samples in the data analysis, surrogate values were estimated following a time-activity model. Twelve long-term personal samples, 2 short-term, 30-min personal samples, and 31 long-term area samples were modeled. Personal and area time-weighted average (TWA) data were analyzed both with and without the estimated surrogate values and compared. A total of 444 samples were collected over 9 days. Four experienced heavy equipment mechanics removed and replaced friction products and gaskets. Samples were analyzed using NIOSH Method 7400 Phase Contrast Microscopy followed by NIOSH Method 7402 Transmission Electron Microscopy. Sample data information including the surrogate values for the full-shift, TWA personal sample results ranged from 0.002 to 0.064 asbestos f/cc. Personal, short-term, 30-min sample results, including the two surrogate values, ranged from 0.038 to 0.561 asbestos f/cc. Full-shift TWA area samples, including the 31 surrogate values, ranged from 0.005 to 0.039 asbestos f/cc. Area air sample results at the end of the project were similar to levels measured before the start of the project. No fiber concentration buildup within the work area was indicated over the 9-day study. All full-shift personal and area TWA sample results were below 0.1 f/cc, and short-term 30-min personal samples were below 1.0 f/cc. Statistical results of the sample data with and without the surrogate values were consistent. Use of the time-activity model reduced the uncertainty associated with this data analysis and provided a consistent logical process for estimating surrogate values to replace missing data. PMID:17503297

  10. Time-Course of Changes in Inflammatory Response after Whole-Body Cryotherapy Multi Exposures following Severe Exercise

    PubMed Central

    Pournot, Hervé; Bieuzen, François; Louis, Julien; Fillard, Jean-Robert; Barbiche, Etienne; Hausswirth, Christophe

    2011-01-01

    The objectives of the present investigation was to analyze the effect of two different recovery modalities on classical markers of exercise-induced muscle damage (EIMD) and inflammation obtained after a simulated trail running race. Endurance trained males (n?=?11) completed two experimental trials separated by 1 month in a randomized crossover design; one trial involved passive recovery (PAS), the other a specific whole body cryotherapy (WBC) for 96 h post-exercise (repeated each day). For each trial, subjects performed a 48 min running treadmill exercise followed by PAS or WBC. The Interleukin (IL) -1 (IL-1), IL-6, IL-10, tumor necrosis factor alpha (TNF-?), protein C-reactive (CRP) and white blood cells count were measured at rest, immediately post-exercise, and at 24, 48, 72, 96 h in post-exercise recovery. A significant time effect was observed to characterize an inflammatory state (Pre vs. Post) following the exercise bout in all conditions (p<0.05). Indeed, IL-1? (Post 1 h) and CRP (Post 24 h) levels decreased and IL-1ra (Post 1 h) increased following WBC when compared to PAS. In WBC condition (p<0.05), TNF-?, IL-10 and IL-6 remain unchanged compared to PAS condition. Overall, the results indicated that the WBC was effective in reducing the inflammatory process. These results may be explained by vasoconstriction at muscular level, and both the decrease in cytokines activity pro-inflammatory, and increase in cytokines anti-inflammatory. PMID:21829501

  11. Exposure variables in ergonomic epidemiology.

    PubMed

    Hagberg, M

    1992-01-01

    The ergonomic field is rather new to epidemiology and ergonomists are usually without knowledge in epidemiology. This review presents exposure variables used in ergonomic epidemiology, especially those that concern mechanical trauma to the musculoskeletal system at the workplace and suggests how to approach exposure definition, exposure assessment, and exposure evaluation. The exposure variables that define the exposure can be divided into five main categories: posture, motion/repetition, material handling, work organization, and external factors. There is no consensus on how different exposure variables should be pooled and interpreted as single estimates of cumulative exposure. For future ergonomic epidemiology, it is suggested that exposure be described by different exposure variables giving an exposure profile and not by a single estimate of the exposure. The possibly short time-response relationship for many work-related musculoskeletal disorders provides a challenge in evaluating different cumulative exposure measures. These measures could easily turn into effective hazard surveillance tools. Large etiological fractions found for some musculoskeletal diseases indicate a great potential for ergonomic interventions. PMID:1553989

  12. Exposure time to caffeine affects heartbeat and cell damage-related gene expression of zebrafish Danio rerio embryos at early developmental stages.

    PubMed

    Abdelkader, Tamer Said; Chang, Seo-Na; Kim, Tae-Hyun; Song, Juha; Kim, Dong Su; Park, Jae-Hak

    2013-11-01

    Caffeine is white crystalline xanthine alkaloid that is naturally found in some plants and can be produced synthetically. It has various biological effects, especially during pregnancy and lactation. We studied the effect of caffeine on heartbeat, survival and the expression of cell damage related genes, including oxidative stress (HSP70), mitochondrial metabolism (Cyclin G1) and apoptosis (Bax and Bcl2), at early developmental stages of zebrafish embryos. We used 100?µm concentration based on the absence of locomotor effects. Neither significant mortality nor morphological changes were detected. We monitored hatching at 48?h post-fertilization (hpf) to 96?hpf. At 60 and 72?hpf, hatching decreased significantly (P??0.05). Heartbeats per minute were 110, 110 and 112 in control at 48, 72 and 96?hpf, respectively. Caffeine significantly increased heartbeat - 122 and 136 at 72 and 96?hpf, respectively. Quantitative RT-PCR showed significant up-regulation after caffeine exposure in HSP70 at 72?hpf; in Cyclin G1 at 24, 48 and 72?hpf; and in Bax at 48 and 72?hpf. Significant down-regulation was found in Bcl2 at 48 and 72?hpf. The Bax/Bcl2 ratio increased significantly at 48 and 72?hpf. We conclude that increasing exposure time to caffeine stimulates oxidative stress and may trigger apoptosis via a mitochondrial-dependent pathway. Also caffeine increases heartbeat from early phases of development without affecting the morphology and survival but delays hatching. Use of caffeine during pregnancy and lactation may harm the fetus by affecting the expression of cell-damage related genes. PMID:22886764

  13. Effects of different inorganic arsenic species in Cyprinus carpio (Cyprinidae) tissues after short-time exposure: bioaccumulation, biotransformation and biological responses.

    PubMed

    Ventura-Lima, Juliane; Fattorini, Daniele; Regoli, Francesco; Monserrat, José M

    2009-12-01

    Differences in the toxicological and metabolic pathway of inorganic arsenic compounds are largely unknown for aquatic species. In the present study the effects of short-time and acute exposure to As(III) and As(V) were investigated in gills and liver of the common carp, Cyprinus carpio (Cyprinidae), measuring accumulation and chemical speciation of arsenic, and the activity of glutathione-S-transferase omega (GST Omega), the rate limiting enzyme in biotransformation of inorganic arsenic. Oxidative biomarkers included antioxidant defenses (total glutathione-S-transferases, glutathione reductase, glutathione, and glucose-6-phosphate dehydrogenase), total scavenging capacity toward peroxyl radicals, reactive oxygen species (ROS) measurement and lipid peroxidation products. A marked accumulation of arsenic was observed only in gills of carps exposed to 1000 ppb As(V). Also in gills, antioxidant responses were mostly modulated through a significant induction of glucose-6-phosphate dehydrogenase activity which probably contributed to reduce ROS formation; however this increase was not sufficient to prevent lipid peroxidation. No changes in metal content were measured in liver of exposed carps, characterized by lower activity of GST Omega compared to gills. On the other hand, glutathione metabolism was more sensitive in liver tissue, where a significant inhibition of glutathione reductase was concomitant with increased levels of glutathione and higher total antioxidant capacity toward peroxyl radicals, thus preventing lipid peroxidation and ROS production. The overall results of this study indicated that exposure of C. carpio to As(III) and As(V) can induce different responses in gills and liver of this aquatic organism. PMID:19632019

  14. Occupational exposure in MRI

    PubMed Central

    Mcrobbie, D W

    2012-01-01

    This article reviews occupational exposure in clinical MRI; it specifically considers units of exposure, basic physical interactions, health effects, guideline limits, dosimetry, results of exposure surveys, calculation of induced fields and the status of the European Physical Agents Directive. Electromagnetic field exposure in MRI from the static field B0, imaging gradients and radiofrequency transmission fields induces electric fields and currents in tissue, which are responsible for various acute sensory effects. The underlying theory and its application to the formulation of incident and induced field limits are presented. The recent International Commission on Non-Ionizing Radiation Protection (ICNIRP) Bundesministerium für Arbeit und Soziales and Institute of Electrical and Electronics Engineers limits for incident field exposure are interpreted in a manner applicable to MRI. Field measurements show that exposure from movement within the B0 fringe field can exceed ICNIRP reference levels within 0.5 m of the bore entrance. Rate of change of field dB/dt from the imaging gradients is unlikely to exceed the new limits, although incident field limits can be exceeded for radiofrequency (RF) exposure within 0.2–0.5 m of the bore entrance. Dosimetric surveys of routine clinical practice show that staff are exposed to peak values of 42±24% of B0, with time-averaged exposures of 5.2±2.8 mT for magnets in the range 0.6–4 T. Exposure to time-varying fields arising from movement within the B0 fringe resulted in peak dB/dt of approximately 2 T s?1. Modelling of induced electric fields from the imaging gradients shows that ICNIRP-induced field limits are unlikely to be exceeded in most situations; however, movement through the static field may still present a problem. The likely application of the limits is discussed with respect to the reformulation of the European Union (EU) directive and its possible implications for MRI. PMID:22457400

  15. Trauma-related shame and guilt as time-varying predictors of posttraumatic stress disorder symptoms during imagery exposure and imagery rescripting-A randomized controlled trial.

    PubMed

    Oktedalen, Tuva; Hoffart, Asle; Langkaas, Tomas Formo

    2014-05-23

    Abstract Objective: The specific aims of this study are to examine trauma-related shame and guilt as time-varying predictors of symptoms of posttraumatic stress disorder (PTSD). Method: Sixty-five patients were included in the statistical analyses and the multilevel modeling analyses supported three major findings. Results: (i) Patients with a higher level of shame and guilt at the start of treatment displayed a higher level of PTSD symptoms over the course of treatment compared to other patients. (ii) Time-specific change in shame and guilt predicted the level of PTSD symptoms 3 days later from session to session during treatment. (iii) No significant differences were evident between prolonged exposure (PE) and modified PE to include imagery rescripting in the within-person process of change in PTSD symptoms from session to session during therapy. Conclusions: This trial reports the first evidence that within-person change in shame and guilt predicts change in PTSD symptoms from session to session during treatment. PMID:24856364

  16. Effect of long-time, elevated-temperature exposures to vacuum and lithium on the properties of a tantalum alloy, T-111

    NASA Technical Reports Server (NTRS)

    Buzzard, R. J.; Sheffler, K. D.

    1974-01-01

    The effect of long-term, elevated-temperature vacuum and lithium exposures on the mechanical properties of T-111 (Ta-8W-2Hf) is determined. Exposure conditions were for 1000 hours at 980 or 1315 C, 5000 hours at 1315 C, and a duplex temperature exposure of 1000 hours at 980 C plus 4000 hours at 1040 C. The exposures resulted in reduced tensile and creep strengths of the T-111 in the 900 to 1100 C temperature range where a dynamic strain-age-strengthening mechanism is operative in this alloy. This strength reduction was attributed to the depletion of oxygen from solid solution in this alloy.

  17. Influence of exposure and infusion times on the cytotoxicity and pharmacokinetics of cis - malonato[(4R, 5R )-4,5-bis(aminomethyl)- 2-isopropyl-1,3-dioxolane]platinum(II)

    Microsoft Academic Search

    Hun-Taek Kim; D.-K. Kim; Yong-Baik Cho; Taek-Soo Kim; I. Jung; Key H. Kim; Dae Seog Heo; Yung-Jue Bang; Sang-Goo Shin; Noe Kyeong Kim

    1997-01-01

    The effect of exposure time on the in vitro cytotoxicity of a new platinum complex, cis-malonato- [(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II) (SKI 2053R) and cisplatin (CDDP) toward two human lung-adenocarcinoma\\u000a cell lines (PC-9, PC-14) and two human stomach-adenocarcinoma cell lines (KATO III, MKN-45) was investigated by variation\\u000a of the exposure time (1, 4, 12, and 24?h) and drug concentration to yield a constant product

  18. Stomatal response and leaf injury of Pisum sativum L. with SO/sub 2/ and O/sub 3/ exposures. II. Influence of moisture stress and time of exposure

    SciTech Connect

    Olszyk, D.M.; Tibbitts, T.W.

    1981-03-01

    Stomatal response during exposure to SO/sub 2/ and O/sub 3/ and subsequent leaf injury were examined in plants of Pisum sativum L. Alsweet grown in a peat-vermiculite medium in controlled environment chambers. Plants developing under moisture stress, induced by drying the medium to 50% of field capacity, exhibited greater stomatal closure during exposures and less than one-fourth the necrosis compared to plants developing in a medium maintained at field capacity. Plants under moisture stress had only a slightly more negative plant water potential (approx. = 4.0 bars) than at field capacity (approx. = 3.4 bars). Plants exposed to pollutants for 2 hours near the beginning or end of a 16-hour light period had greater stomatal closure during exposures and less leaf necrosis than plants exposed during the middle of the light period.

  19. Time course of inhibition of cholinesterase and aliesterase activities, and nonprotein sulfhydryl levels following exposure to organophosphorus insecticides in mosquitofish (Gambusia affinis).

    PubMed

    Boone, J S; Chambers, J E

    1996-02-01

    Cholinesterase (ChE) in brain and muscle was quickly inhibited during a 48-hr in vivo exposure to chlorpyrifos (0.1 ppm), parathion (0.15 ppm), and methyl parathion (8 ppm) in mosquitofish (Gambusia affinis). ChE remained inhibited during a 96-hr nonexposure period. Brain ChE reached peak inhibition by 12 hr after exposure to parathion and chlorpyrifos and by 4 hr after exposure to methyl parathion. All insecticides caused greater than 70% ChE inhibition by 4 hr in muscle. There was no recovery of ChE after 4 days of nonexposure in either brain or muscle. Hepatic aliesterases (AliE) were quickly and greatly inhibited (> 70% by 4 hr) after exposure to parathion and chlorpyrifos but not after exposure to methyl parathion. Exposure to methyl parathion required 24-36 hr to inhibit hepatic AliE to the same level as that following parathion and chlorpyrifos exposures at 4 hr. Exposure to all insecticides eventually resulted in greater than 80% inhibition of AliE. None of the test groups treated with insecticides showed any signs of significant recovery of AliE during the 4 days of nonexposure. Nonprotein sulfhydryl (NPSH) concentrations were lower than controls after 24 hr of exposure and 96 hr after recovery for all compounds. Exposure to methyl parathion lowered NPSH concentrations greater than the other compounds. Hepatic AliE appear capable of affording some protection of ChE from inhibition following parathion or chlorpyrifos exposures, but considerably less protection against methyl parathion. PMID:8742317

  20. Electronic platform for real-time multi-parametric analysis of cellular behavior post-exposure to single-walled carbon nanotubes.

    PubMed

    Eldawud, Reem; Wagner, Alixandra; Dong, Chenbo; Rojansakul, Yon; Zoica Dinu, Cerasela

    2015-09-15

    Single-walled carbon nanotubes (SWCNTs) implementation in a variety of biomedical applications from bioimaging, to controlled drug delivery and cellular-directed alignment for muscle myofiber fabrication, has raised awareness of their potential toxicity. Nanotubes structural aspects which resemble asbestos, as well as their ability to induce cyto and genotoxicity upon interaction with biological systems by generating reactive oxygen species or inducing membrane damage, just to name a few, have led to focused efforts aimed to assess associated risks prior their user implementation. In this study, we employed a non-invasive and real-time electric cell impedance sensing (ECIS) platform to monitor behavior of lung epithelial cells upon exposure to a library of SWCNTs with user-defined physico-chemical properties. Using the natural sensitivity of the cells, we evaluated SWCNT-induced cellular changes in relation to cell attachment, cell-cell interactions and cell viability respectively. Our methods have the potential to lead to the development of standardized assays for risk assessment of other nanomaterials as well as risk differentiation based on the nanomaterials surface chemistry, purity and agglomeration state. PMID:25913448

  1. Results of time-resolved radiation exposure measurements made during U.S. shuttle missions with a tissue equivalent proportional counter

    NASA Technical Reports Server (NTRS)

    Golightly, M. J.; Hardy, A. C.; Hardy, K.

    1994-01-01

    Time resolved exposure measurements inside the crew compartment have been made during recent shuttle missions with the USAF Radiation Monitoring Equipment-III (RME-III), a portable four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. The missions had orbital inclinations ranging from 28 degrees to 57 degrees, and altitudes from 200-600km. Dose equivalent rates ranged from 40-5300 micro Sv/dy. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicle. Measurements indicate that medium- and high- Linear Energy Transfer (LET) particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Isa-dose rate contours have been developed from measurements made during the ST-28 mission. The drift rate of the South Atlantic Anomaly (SAA) is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and Galactic Cosmic Radiation (GCR) dose for the STS-28 mission were significantly lower than the measured values.

  2. A time-course transcriptional kinetics of the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal axes in zebrafish eleutheroembryos after exposure to norgestrel.

    PubMed

    Liang, Yan-Qiu; Huang, Guo-Yong; Ying, Guang-Guo; Liu, Shuang-Shuang; Jiang, Yu-Xia; Liu, Shan; Peng, Feng-Jiao

    2015-01-01

    The objective of the present study was to investigate the effects of norgestrel on the hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-adrenal (HPA) axes in zebrafish eleutheroembryos. Zebrafish embryos were exposed to different concentrations of norgestrel (0?ng?L(-1) , 5?ng?L(-1) , 50?ng?L(-1) , and 100?ng?L(-1) ) for 144?h post fertilization (hpf), and the transcriptional profiles of the HPG and HPA axes were examined every day. Norgestrel modulated the expression of Pgr and Vtg1 messenger (m)RNAs mainly at 96 hpf for all treatment groups. In addition, norgestrel strongly altered the expression of Cyp11a1 mRNA above 5?ng?L(-1) (significant upregulation from 48 hpf to 120 hpf and significant downregulation for 144 hpf). Norgestrel treatment could significantly induce expression of Cyp19a1a, Cyp11b, Gnrh2, Gnrh3, and Lhb mRNAs but inhibit transcripts of Hsd11b2 and Crh genes above 5?ng?L(-1) at different time points. The transcriptional expression levels of Esr1, Ar, Star, Hsd17b3, Fshb, and Pomc were also mediated by 5?ng?L(-1) norgestrel or higher during different exposure periods. Taken together, the overall results imply that the transcriptional changes in zebrafish eleutheroembryos may pose a potential effect on embryonic development, in particular in the brain and gonadogenesis. PMID:25319565

  3. Effect of occupational polychlorinated biphenyls exposure on quality-adjusted life years over time at the HELPcB surveillance program.

    PubMed

    Esser, A; Gaum, P M; Schettgen, T; Kraus, T; Gube, M; Lang, J

    2015-01-01

    HELPcB (Health Effects in High-Level Exposure to Polychlorinated Biphenyls [PCB]) is a surveillance program for former PCB-exposed workers of a capacitor recycling company and other concerned individuals. The aim of this study was to examine the influence of polychlorinated biphenyls (PCB) on the health-related quality of life (HRQL) and on quality-adjusted life years (QALY). The EQ-5D-3L questionnaire was used to determine the HRQL. After three cross-sectional examinations at intervals of 1 yr, the longitudinal development of QALY was compared by repeated-measurement analysis of covariance (ANCOVA). The cohort was split at the 95th percentile of the comparison group for each PCB congener; known confounders such as age were taken into account. A significant difference in height and development of QALY over time was shown for the higher chlorinated non-dioxin-like PCB (hcPCB) congeners. A significant between-groups effect was found on PCB 153, PCB 180, and the sum of hcPCB. It was found that QALY decreased in the high-burden group and QALY stabilized after yr 2 in the normal-burden group. Taking the dimensions of the EQ-5D into account, the between-groups effect seems to be based predominantly on the dimension anxiety. The development of the within-group effect, however, seems to be based on the dimension mobility. This study detected a significant influence of hcPCB on the development of HRQL and QALYs over time according to the level of internal PCB burden. PMID:25424621

  4. Effects of Prenatal Exposure to a Low Dose Atrazine Metabolite Mixture on pubertal timing and prostrate Development of Male Long Evans Rats.

    EPA Science Inventory

    The present study examines the postnatal reproductive development of male rats following prenatal exposure to an atrazine metabolite mixture (AMM) consisting of the herbicide atrazine and its environmental metabolites diaminochlorotriazine, hydroxyatrazine, deethylatrazine, and d...

  5. Time Trends of Polycyclic Aromatic Hydrocarbon Exposure in New York City from 2001 to 2012: Assessed by Repeat Air and Urine Samples

    PubMed Central

    Jung, Kyung Hwa; Liu, Bian; Lovinsky-Desir, Stephanie; Yan, Beizhan; Camann, David; Sjodin, Andreas; Li, Zheng; Perera, Frederica; Kinney, Patrick; Chillrud, Steven; Miller, Rachel L.

    2014-01-01

    Background Exposure to air pollutants including polycyclic aromatic hydrocarbons (PAH), and specifically pyrene from combustion of fuel oil, coal, traffic and indoor sources, has been associated with adverse respiratory health outcomes. However, time trends of airborne PAH and metabolite levels detected via repeat measures over time have not yet been characterized. We hypothesized that PAH levels, measured repeatedly from residential indoor and outdoor monitors, and children’s urinary concentrations of PAH metabolites, would decrease following policy interventions to reduce traffic-related air pollution. Methods Indoor PAH (particle- and gas-phase) were collected for two weeks prenatally (n=98), at age 5/6 years (n=397) and age 9/10 years (n=198) since 2001 and at all three age-points (n=27). Other traffic-related air pollutants (black carbon and PM2.5) were monitored indoors simultaneous with PAH monitoring at ages 5/6 (n=403) and 9/10 (n=257) between 2005 and 2012. One third of the homes were selected across seasons for outdoor PAH, BC and PM2.5 sampling. Using the same sampling method, ambient PAH, BC and PM2.5 also were monitored every two weeks at a central site between 2007 and 2012. PAH were analyzed as semivolatile PAH (e.g., pyrene; MW 178–206) and the sum of eight nonvolatile PAH (?8PAHnonvolatile; MW 228–278). A spot urine sample was collected from children at child ages 3, 5, 7 and 9 between 2001 and 2012 and analyzed for 10 PAH metabolites. Results Modest declines were detected in indoor BC and PM2.5 levels between 2005 and 2012 (Annual percent change [APC]=?2.08% [p=0.010] and ?2.18% [p=0.059] for BC and PM2.5, respectively), while a trend of increasing pyrene levels was observed in indoor and outdoor samples, and at the central site during the comparable time periods (APC=4.81%, 3.77% and 7.90%, respectively; p<0.05 for all). No significant time trend was observed in indoor ?8PAHnonvolatile levels between 2005 and 2012; however, significant opposite trends were detected when analyzed seasonally (APC=?8.06% [p<0.01], 3.87% [p<0.05] for nonheating and heating season, respectively). Similarly, heating season also affected the annual trends (2005–2012) of other air pollutants: the decreasing BC trend (in indoor/outdoor air) was observed only in the nonheating season, consistent with dominating traffic sources that decreased with time; the increasing pyrene trend was more apparent in the heating season. Outdoor PM2.5 levels persistently decreased over time across the seasons. With the analyses of data collected over a longer period of time (2001–2012), a decreasing trend was observed in pyrene (APC=?2.76%; p<0.01), mostly driven by measures from the nonheating season (APC=?3.54%; p<0.01). In contrast, levels of pyrene and naphthalene metabolites, 1-hydroxypyrene and 2-naphthol, increased from 2001 to 2012 (APC=6.29% and 7.90% for 1-hydroxypyrene and 2-naphthol, respectively; p<0.01 for both). Conclusions Multiple NYC legislative regulations targeting traffic-related air pollution may have led to decreases in ?8PAHnonvolatile and BC, especially in the nonheating season. Despite the overall decrease in pyrene over the 2001–2012 periods, a rise in pyrene levels in recent years (2005–2012), that was particularly evident for measures collected during the heating season, and 2-naphthol, indicates the contribution of heating oil combustion and other indoor sources to airborne pyrene and urinary 2-naphthol. PMID:24709094

  6. Time Course of Inhibition of Cholinesterase and Aliesterase Activities, and Nonprotein Sulfhydryl Levels Following Exposure to Organophosphorus Insecticides in Mosquitofish ( Gambusia affinis)

    Microsoft Academic Search

    J. Scott Boone; Janice E. Chambers

    1996-01-01

    Cholinesterase (ChE) in brain and muscle was quickly inhibited during a 48-hrin vivoexposure to chlorpyrifos (0.1 ppm), parathion (0.15 ppm), and methyl parathion (8 ppm) in mosquitofish (Gambusia affinis). ChE remained inhibited during a 96-hr nonexposure period. Brain ChE reached peak inhibition by 12 hr after exposure to parathion and chlorpyrifos and by 4 hr after exposure to methyl parathion.

  7. A spatially disaggregated time-series analysis of the short-term effects of particulate matter exposure on mortality in Chennai, India

    Microsoft Academic Search

    Kalpana Balakrishnan; Bhaswati Ganguli; Santu Ghosh; Sankar Sambandam; Sugata Sen Roy; Aditya Chatterjee

    The global burden of disease due to air pollution is concentrated in the rapidly developing counties of Asia, but a recent\\u000a meta-analysis found that relatively few studies on short-term exposure to air pollution and mortality have been performed\\u000a in these countries, including India. Local evidence on the effects of short-term exposures to air pollutants on mortality\\u000a and cardio-respiratory morbidity in

  8. Criminal exposure.

    PubMed

    1999-08-01

    A 39-year-old man who had sex with a 16-year-old boy, was sentenced to five years in prison. The defendant pleaded guilty to statutory rape and criminal exposure to HIV. The boy discovered that the man was taking HIV medications, and the man subsequently disclosed his treatment after being arrested. PMID:11367003

  9. Gut-Homing Conventional Plasmablasts and CD27? Plasmablasts Elicited after a Short Time of Exposure to an Oral Live-Attenuated Shigella Vaccine Candidate in Humans

    PubMed Central

    Toapanta, Franklin R.; Simon, Jakub K.; Barry, Eileen M.; Pasetti, Marcela F.; Levine, Myron M.; Kotloff, Karen L.; Sztein, Marcelo B.

    2014-01-01

    Currently, there is no licensed Shigella vaccine; however, various promising live-attenuated vaccine candidates have emerged, including CVD1208S (?guaBA, ?set, ?sen S. flexneri 2a), which was shown to be safe and immunogenic in Phase 1 clinical trials. Here, we report the immune responses elicited in an outpatient Phase 2 clinical trial in which subjects were vaccinated with CVD 1208S. Oral immunization with CVD 1208S elicited high anti-S. flexneri 2a LPS and IpaB antibody responses as well as an acute plasmablast (PB) infiltration in peripheral blood 7?days after immunization. PB sorted based on their expression of homing molecules confirmed that cells expressing integrin ?4?7 alone or in combination with CD62L were responsible for antibody production (as measured by ELISpot). Furthermore, using high-color flow-cytometry, on day 7 after immunization, we observed the appearance of conventional PB (CPB, CD19dim CD20? CD27+high CD38+high CD3?), as well as a PB population that did not express CD27 (CD27? PB; pre-plasmablasts). The pattern of individual or simultaneous expression of homing markers (integrin ?4?7, CD62L, CXCR3, and CXCR4) suggested that CPB cells homed preferentially to the inflamed gut mucosa. In contrast, ~50% CD27? PB cells appear to home to yet to be identified peripheral lymphoid organs or were in a transition state preceding integrin ?4?7 upregulation. In sum, these observations demonstrate that strong immune responses, including distinct PB subsets with the potential to home to the gut and other secondary lymphoid organs, can be elicited after a short time of exposure to a shigella oral vaccine. PMID:25191323

  10. HUMAN EXPOSURE MODELING: CONCEPTS, METHODS, AND TOOLS

    EPA Science Inventory

    Understanding human exposure is critical when estimating the occurrence of deleterious effects that could follow contact with environmental contaminants. For many pollutants, the intensity, duration, frequency, route, and timing of exposure is highly variable, particularly whe...

  11. EXCOMP: an exposure comparison methodology

    SciTech Connect

    Lavender, J.C.; Franklin, A.L.

    1986-01-01

    When designing new facilities or modifying existing facilities that involve radioactive material, handling or processing, an area of concern is the radiological exposure received by facility personnel and the environment. The computerized models that are currently used for exposure evaluations are capable of evaluating only one relationship at a time, i.e., the effects of one source, its strength and location, on one work location. EXCOMP (EXposure COMParison) is a methodology developed for the IBM-PC to evaluate radiological exposures. It is capable of evaluating each identified work location in a facility with respect to each identified source effecting it.

  12. Altered gene expression by low-dose arsenic exposure in humans and cultured cardiomyocytes: Assessment by real-time PCR array

    EPA Science Inventory

    Arsenic contamination in drinking water has become a great public health concern worldwide. Chronic arsenic exposure results in higher risk of skin, lung and bladder cancer, as well as cardiovascular disease and diabetes. The purpose of this study was to investigate the effects o...

  13. ATTENUATION OF STATISTICAL RELATIONSHIPS FROM PM COMMUNITY TIME-SERIES EPIDEMIOLOGY DUE TO USE OF COMBINED, RATHER THAN SEPARATE, INDICATORS OF EXPOSURE AND MORTALITY

    EPA Science Inventory

    Attenuation of the statistical relationships between PM and health outcomes may arise from 1) combining exposure indicators, e.g., PM10 instead of PM2.5 and PM10-2.5 or 2) from combining different types of mortality. The Phoenix, AZ data base on air quality offers an opportunity...

  14. Turbulent times: effects of turbulence and violence exposure in adolescence on high school completion, health risk behavior, and mental health in young adulthood.

    PubMed

    Boynton-Jarrett, Renée; Hair, Elizabeth; Zuckerman, Barry

    2013-10-01

    Turbulent social environments are associated with health and developmental risk, yet mechanisms have been understudied. Guided by a life course framework and stress theory, this study examined the association between turbulent life transitions (including frequent residential mobility, school transitions, family structure disruptions, and homelessness) and exposure to violence during adolescence and high school completion, mental health, and health risk behaviors in young adulthood. Participants (n = 4834) from the U.S. National Longitudinal Survey of Youth, 1997 cohort were followed prospectively from age 12-14 years for 10 years. We used structural equation models to investigate pathways between turbulence and cumulative exposure to violence (CEV), and high school completion, mental health, and health risk behaviors, while accounting for early life socio-demographics, family processes, and individual characteristics. Results indicated that turbulence index was associated with cumulative exposure to violence in adolescence. Both turbulence index and cumulative exposure to violence were positively associated with higher health risk behavior, poorer mental health, and inversely associated with high school completion. These findings highlight the importance of considering the cumulative impact of turbulent and adverse social environments when developing interventions to optimize health and developmental trajectory for adolescents transitioning into adulthood. PMID:23063217

  15. Social Competence in Children at Risk Due to Prenatal Cocaine Exposure: Continuity over Time and Associations with Cognitive and Language Abilities

    ERIC Educational Resources Information Center

    Acra, C. Francoise; Bono, Katherine E.; Mundy, Peter C.; Scott, Keith G.

    2009-01-01

    The continuity of social competence between 36 months and first grade was examined in a sample of children at risk due to prenatal exposure to cocaine (N = 92). Parent report data on social competence were collected at 36 months of age and both parent and teacher report data were collected when children were in first grade. Regression analyses…

  16. Radiation Risk from Chronic Low Dose-Rate Radiation Exposures: The Role of Life-Time Animal Studies - Workshop October 2005

    SciTech Connect

    Gayle Woloschak

    2009-12-16

    As a part of Radiation research conference, a workshop was held on life-long exposure studies conducted in the course of irradiation experiements done at Argonne National Laboratory between 1952-1992. A recent review article documents many of the issues discussed at that workshop.

  17. Relative-risk-estimate bias and loss of power in the Mantel test for trend resulting from the use of magnetic-field point-in-time (spot) measurements in epidemiological studies based on an ordinal exposure scale

    Microsoft Academic Search

    Vincent Delpizzo; Michael R. Salzberg

    1992-01-01

    We assessed the merits of various point-in-time (spot) measurement protocols in case-control studies based on an ordinal exposure scale. After classifying a number of houses on the basis of prolonged monitoring of the ambient, extremely low frequency (ELF) magnetic field, we determined the probability of misclassification for each spot measurement protocol. We calculated the effect of this misclassification on the

  18. Exposure to toxic environmental agents.

    PubMed

    2013-10-01

    : Reducing exposure to toxic environmental agents is a critical area of intervention for obstetricians, gynecologists, and other reproductive health care professionals. Patient exposure to toxic environmental chemicals and other stressors is ubiquitous, and preconception and prenatal exposure to toxic environmental agents can have a profound and lasting effect on reproductive health across the life course. Prenatal exposure to certain chemicals has been documented to increase the risk of cancer in childhood; adult male exposure to pesticides is linked to altered semen quality, sterility, and prostate cancer; and postnatal exposure to some pesticides can interfere with all developmental stages of reproductive function in adult females, including puberty, menstruation and ovulation, fertility and fecundity, and menopause. Many environmental factors harmful to reproductive health disproportionately affect vulnerable and underserved populations, which leaves some populations, including underserved women, more vulnerable to adverse reproductive health effects than other populations. The evidence that links exposure to toxic environmental agents and adverse reproductive and developmental health outcomes is sufficiently robust, and the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine join leading scientists and other clinical practitioners in calling for timely action to identify and reduce exposure to toxic environmental agents while addressing the consequences of such exposure. PMID:24084567

  19. Exposure to toxic environmental agents.

    PubMed

    2013-10-01

    Reducing exposure to toxic environmental agents is a critical area of intervention for obstetricians, gynecologists, and other reproductive health care professionals. Patient exposure to toxic environmental chemicals and other stressors is ubiquitous, and preconception and prenatal exposure to toxic environmental agents can have a profound and lasting effect on reproductive health across the life course.Prenatal exposure to certain chemicals has been documented to increase the risk of cancer in childhood; adult male exposure to pesticides is linked to altered semen quality, sterility, and prostate cancer; and postnatal exposure to some pesticides can interfere with all developmental stages of reproductive function in adult females, including puberty, menstruation and ovulation, fertility and fecundity, and menopause. Many environmental factors harmful to reproductive health disproportionately affect vulnerable and underserved populations,which leaves some populations, including underserved women, more vulnerable to adverse reproductive health effects than other populations. The evidence that links exposure to toxic environmental agents and adverse reproductive and developmental health outcomes is sufficiently robust, and the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine join leading scientists and other clinical practitioners in calling for timely action to identify and reduce exposure to toxic environmental agents while addressing the consequences of such exposure. PMID:24070500

  20. Climatic and topographic controls on the style and timing of Late Quaternary glaciation throughout Tibet and the Himalaya defined by 10Be cosmogenic radionuclide surface exposure dating

    USGS Publications Warehouse

    Owen, L.A.; Finkel, R.C.; Barnard, P.L.; Haizhou, Ma; Asahi, K.; Caffee, M.W.; Derbyshire, E.

    2005-01-01

    Temporal and spatial changes in glacier cover throughout the Late Quaternary in Tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region, and the lack of numerical dating. To help reconstruct the timing and extent of glaciation throughout Tibet and the bordering mountains, we use geomorphic mapping and 10Be cosmogenic radionuclide (CRN) surface dating in study areas in southeastern (Gonga Shan), southern (Karola Pass) and central (Western Nyainqentanggulha Shan and Tanggula Shan) Tibet, and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands. Each of the study regions receives its precipitation mainly during the south Asian summer monsoon when it falls as snow at high altitudes. Gonga Shan receives the most precipitation (>2000 mm a-1) while, near the margins of monsoon influence, the Karola Pass receives moderate amounts of precipitation (500-600 mm a-1) and, in the interior of the plateau, little precipitation falls on the western Nyainqentanggulha Shan (???300 mm a -1) and the Tanggula Shan (400-700 mm a-1). The higher precipitation values for the Tanggula Shan are due to strong orographic effects. In each region, at least three sets of moraines and associated landforms are preserved, providing evidence for multiple glaciations. The 10Be CRN surface exposure dating shows that the formation of moraines in Gonga Shan occurred during the early-mid Holocene, Neoglacial and Little Ice Age, on the Karola Pass during the Lateglacial, Early Holocene and Neoglacial, in the Nyainqentanggulha Shan date during the early part of the last glacial cycle, global Last Glacial Maximum and Lateglacial, and on the Tanggula Shan during the penultimate glacial cycle and the early part of the last glacial cycle. The oldest moraine succession in each of these regions varies from the early Holocene (Gonga Shan), Lateglacial (Karola Pass), early Last Glacial (western Nyainqentanggulha Shan), and penultimate glacial cycle (Tanggula Shan). We believe that the regional patterns and timing of glaciation reflect temporal and spatial variability in the south Asian monsoon and, in particular, in regional precipitation gradients. In zones of greater aridity, the extent of glaciation has become increasingly restricted throughout the Late Quaternary leading to the preservation of old (???100 ka) glacial landforms. In contrast, in regions that are very strongly influenced by the monsoon (???1600 mm a-1), the preservation potential of pre-Lateglacial moraine successions is generally extremely poor. This is possibly because Lateglacial and Holocene glacial advances may have been more extensive than early glaciations and hence may have destroyed any landform or sedimentary evidence of earlier glaciations. Furthermore, the intense denudation, mainly by fluvial and mass movement processes, which characterize these wetter environments, results in rapid erosion and re-sedimentation of glacial and associated landforms, which also contributes to their poor preservation potential. ?? 2004 Elsevier Ltd. All rights reserved.

  1. Use of Finite-Difference Time-Domain Method with AN Anatomically Based Model of a Human for Exposures to Far-Near Fields and Electromagnetic Pulse

    NASA Astrophysics Data System (ADS)

    Chen, Jinyuan

    The three-dimensional finite-difference time-domain (FDTD) method has been used to calculate local, layer-averaged and whole-body averaged specific absorption rates (SARs) and internal radio-frequency (RF) currents in an anatomically -based model of a human for plane-wave (far-field) exposures from 20 to 100 MHz and for spatially variable electromagnetic fields of a parallel-plate applicator representative of RF dielectric heaters used in industry (near-field). The calculated results are in agreement with the experimental data of Hill and others. While the existence of large foot currents has been known previously, substantial RF currents (600-800 mA) induced over much of the body are obtained for E-polarized fields suggested in the 1982 ANSI RF safety guideline. The FDTD method has also been used for simulating Annular Phased Array (APA) of dipole antennas for hyperthermia of deep-seated tumors. Anatomically-based models based on two different regions of the human body (14,417 and 13,133 cells) were used to calculated the SAR distributions with a resolution of 1.31 cm. Annular-phased arrays of eight dipole antennas couple to the human body through either a homogeneous or a tapered water bolus with air assumed outside the ring of dipoles. The objective of the calculations was to focus the energy to a couple of assumed tumor sites in the liver or the prostate. The geometrical optics approximation and principle of focused arrays were used to estimate the phases for individual dipoles to focus the electromagnetic energy into the tumor and its surrounding. Considerably focused power distributions with SARs on the order of 100 W/Kg for input powers of 400-700 W have been obtained for assumed tumor sites in the liver and the prostate using tapered boluses and optimized magnitudes and phases of power to the various dipoles. Lastly the FDTD technique is used to calculate the internal fields and the induced current densities in anatomically based models of a human using 5,628 or 45,024 cubical cells of dimensions 2.62 or 1.31 cm, respectively. The total induced currents for the various sections of the body and the specific absorptions (SA) for several organs are given for a few representative EMPs. Peak currents approximately 3-4 A/(KV/m) are obtained for sections of the thighs and knees for times on the order of 11-12 ns after the onset of the pulse. It is also observed that the predominant components of the induced currents are at frequencies close to 40-45 MHz because of the resonance absorption of the anatomically-based model representing a 1.75-m-tall human standing on a ground plane.

  2. Exposure guidelines for magnetic fields

    SciTech Connect

    Miller, G.

    1987-12-01

    The powerful magnetic fields produced by a controlled fusion experiment at Lawrence Livermore National Laboratory (LLNL) necessitated the development of personnel-exposure guidelines for steady magnetic fields. A literature search and conversations with active researchers showed that it is currently possible to develop preliminary exposure guidelines for steady magnetic fields. An overview of the results of past research into the bioeffects of magnetic fields was compiled, along with a discussion of hazards that may be encountered by people with sickle-cell anemia or medical electronic and prosthetic implants. The LLNL steady magnetic-field exposure guidelines along with a review of developments concerning the safety of time-varying fields were also presented in this compilation. Guidelines developed elsewhere for time varying fields were also given. Further research is needed to develop exposure standards for both steady or time-varying fields.

  3. Exposure matrix development for the Libby cohort.

    PubMed

    Noonan, C W

    2006-11-01

    The Libby, MT, cohort includes current and former residents with potential historical exposure to asbestos-contaminated vermiculite. This cohort includes individuals with a broad range of exposure experiences and work histories. While both occupational and nonoccupational exposure pathways were found to be relevant in recent investigations of health effects among this cohort, there has not been a comprehensive approach to characterizing these varied exposure pathways. Any approach toward assessing historical exposures among this population must account for three general categories: (1) occupational exposures, (2) residential exposures, and (3) exposures related to a variety of nonoccupational activities thought to be associated with vermiculite/asbestos exposure in this community. First, a job exposure matrix is commonly used in occupational epidemiology to assess historical worker exposures, allowing for the incorporation of numerous occupational categories and weighting factors applied to specific jobs for different time periods. Second, residential exposures can best be quantified by integrating individuals' residential histories with data on environmental asbestos contamination in the community. Previous soil or sediment sampling as well as air modeling could inform estimates of time- and spatial-dependent exposure concentrations for a residential exposure matrix. Finally, exposure opportunities due to nonoccupational activities could be weighted by factors such as time, geography, environmental sampling, and an assessment of the relative importance for each pathway. These three matrices for occupational, residential, and activity exposure pathways could be combined or used separately to provide a more comprehensive and quantitative, or semiquantitative, assessment of individual exposure in future epidemiological studies of this cohort. PMID:16920669

  4. Differential Cytokine mRNA Expression in Mice after Oral Exposure to the Trichothecene Vomitoxin (Deoxynivalenol): Dose Response and Time Course

    Microsoft Academic Search

    Hui-Ren Zhou; Ding Yan; James J. Pestka

    1997-01-01

    Acute oral exposure of B6C3F1 mice to vomitoxin (VT) has been previously shown to induce expression of mRNAs for cytokines that are characteristically produced in lymphoid tissues by macrophage and T cells. The purpose of this study was to evaluate the effects of VT dose on the expression of mRNAs for a cytokine profile consisting of TNF-?, IL-1?, IL-6, IL-12,

  5. Inhaled cationic amphiphilic drug-induced pulmonary phospholipidosis in rats and dogs: time-course and dose–response of biomarkers of exposure and effect

    Microsoft Academic Search

    Jürgen Pauluhn

    2005-01-01

    This study compares the pulmonary response to an inhaled highly soluble hydrochloride (CAD-HCl) with a low soluble sulphate salt (CAD-SO4) of a dicationic amphiphilic drug (CAD). These salts are known to accumulate in the lung. The bioavailability through gastrointestinal uptake is poor. Wistar rats and beagle dogs received repeated 1h\\/day inhalation exposures over 1–4 weeks. The focus of this analysis

  6. Criminal exposure.

    PubMed

    1999-10-29

    [Name removed] was sentenced to 17 years in prison after he pleaded guilty in Knox County (Tennessee) Criminal Court to exposing three women to HIV through sex. One of the women is a 17-year-old who became infected and pregnant. The other two women came forward after learning that [name removed] was being investigated for rape involving the 17-year-old. [Name removed] could have been sentenced to up to 60 years for nine counts of criminal exposure to HIV and three counts of statutory rape. In 1994, [name removed] was charged in Michigan with having unprotected sex with HIV; those charges were dropped when the woman involved declined to pursue the case. PMID:11367055

  7. Toxicity of o,p?-DDE to medaka d-rR strain after a one-time embryonic exposure by in ovo nanoinjection: An early through juvenile life cycle assessment

    USGS Publications Warehouse

    Villalobos, Sergio A.; Papoulias, Diana M.; Pastva, Stephanie D.; Blankenship, Alan L.; Meadows, John C.; Tillitt, Donald E.; Giesy, John P.

    2003-01-01

    The toxicity of o,p???-DDE (1,1-dichloro-2-(p-chlorophenyl)-2-(o- chlorophenyl) ethylene) was evaluated in embryos of medaka (Oryzias latipes) following a one time exposure via nanoinjection. Medaka eggs (early gastrula) were injected with 0.5 nl of triolein (vehicle control) or 0.5 nl of 4 graded doses (0.0005-0.5 ng/egg) of o,p???-DDE in triolein. Embryos were allowed to develop, and fry were reared. Embryonic survival was monitored daily during the first 10 d until hatching and thereafter, on a weekly basis until day 59, at which time the fish were monitored for sexual maturity until day 107. In general, o,p???-DDE caused a dose- and time-dependent mortality. No changes in mortality were observed between the last two time points (day 38 and 59, respectively), and hence a 59 day-LD50 of 346 ng o,p???-DDE/egg was derived from the linear dose-response relationship. Prior to late stage death, only isolated cases of cardiovascular lesions and spinal deformities were observed, but were not dose-dependent. The lowest observable adverse effect level (LOAEL), based on upper 95% CI for regression line=0.0018 mg/kg, and the LOAEL based on exposure doses=0.5 mg/kg. Likewise, the no observable adverse effect level (NOAEL) based on linear extrapolation to 100% survival=0.0000388 mg/kg, while the NOAEL based on exposure doses=0.05 mg/kg. The nanoinjection medaka model has potential in the study of hormonally active compounds in the environment. ?? 2003 Elsevier Ltd. All rights reserved.

  8. Solar UVA exposures

    NASA Astrophysics Data System (ADS)

    Parisi, Alfio V.; Kimlin, Michael G.

    2005-08-01

    Exposures to UVA radiation (320 - 400 nm) have been linked to increasing the risk of skin cancer, premature skin photoageing and skin wrinkling. The relative proportion of the UVA irradiances in the solar spectrum changes with time of day and season. Material such as window glass found in offices, homes and motor vehicles acts as a barrier to the shorter solar UVB wavelengths (280 - 320 nm) and transmits some of the longer UVA wavelengths (dependent on the type of glass). As a result, the spectrum of the filtered UV transmitted through the material may be substantially different from that of the unfiltered solar UV spectrum. This results in a change in the relative ratio of UVA to UVB irradiances and a consequent change in the biologically damaging UV exposures. For these environments where the UVB wavelengths have been removed and the UVA wavelengths are still present, it is necessary to consider the erythemal irradiances due to these UVA wavelengths only. This paper investigates the times taken for an exposure of 1 SED (standard erythemal dose) due to the UVA wavelengths.

  9. Times

    NSDL National Science Digital Library

    In this activity learners explore the connections of digital time displays with numeric and geometric properties. Students look for times that have bilateral or rotational symmetry, or have a certain digital sum, etc. Ideas for implementation, extension and support are included.

  10. Effects of prenatal exposure to a low dose atrazine metabolite mixture on pubertal timing and prostate development of male Long-Evans rats

    SciTech Connect

    Stanko, Jason [National Institute of Environmental Health Sciences (NIEHS); Enoch, Rolondo [North Carolina Central University, Durham; Rayner, Jennifer L [ORNL; Davis, Christine [U.S. Environmental Protection Agency; Wolf, Douglas [U.S. Environmental Protection Agency; Malarkey, David [University of North Carolina, Chapel Hill; Fenton, Suzanne [National Institute of Environmental Health Sciences (NIEHS)

    2010-12-01

    The present study examines the postnatal reproductive development of male rats following prenatal exposure to an atrazine metabolite mixture (AMM) consisting of the herbicide atrazine and its environmental metabolites diaminochlorotriazine, hydroxyatrazine, deethylatrazine, and deisopropylatrazine. Pregnant Long-Evans rats were treated by gavage with 0.09, 0.87, or 8.73 mg AMM/kg body weight (BW), vehicle, or 100 mg ATR/kg BW positive control, on gestation days 15 19. Preputial separation was significantly delayed in 0.87 mg and 8.73 mg AMM-exposed males. AMM-exposed males demonstrated a significant treatment-related increase in incidence and severity of inflammation in the prostate on postnatal day (PND) 120. A dose-dependent increase in epididymal fat masses and prostate foci were grossly visible in AMM-exposed offspring. These results indicate that a short, late prenatal exposure to mixture of chlorotriazine metabolites can cause chronic prostatitis in male LE rats. The mode of action for these effects is presently unclear.

  11. A systems biology approach reveals the dose- and time-dependent effect of primary human airway epithelium tissue culture after exposure to cigarette smoke in vitro.

    PubMed

    Mathis, Carole; Gebel, Stephan; Poussin, Carine; Belcastro, Vincenzo; Sewer, Alain; Weisensee, Dirk; Hengstermann, Arnd; Ansari, Sam; Wagner, Sandra; Peitsch, Manuel C; Hoeng, Julia

    2015-01-01

    To establish a relevant in vitro model for systems toxicology-based mechanistic assessment of environmental stressors such as cigarette smoke (CS), we exposed human organotypic bronchial epithelial tissue cultures at the air liquid interface (ALI) to various CS doses. Previously, we compared in vitro gene expression changes with published human airway epithelia in vivo data to assess their similarities. Here, we present a follow-up evaluation of these in vitro transcriptomics data, using complementary computational approaches and an integrated mRNA-microRNA (miRNA) analysis. The main cellular pathways perturbed by CS exposure were related to stress responses (oxidative stress and xenobiotic metabolism), inflammation (inhibition of nuclear factor-?B and the interferon gamma-dependent pathway), and proliferation/differentiation. Within post-exposure periods up to 48 hours, a transient kinetic response was observed at lower CS doses, whereas higher doses resulted in more sustained responses. In conclusion, this systems toxicology approach has potential for product testing according to "21st Century Toxicology". PMID:25788831

  12. A Systems Biology Approach Reveals the Dose- and Time-Dependent Effect of Primary Human Airway Epithelium Tissue Culture After Exposure to Cigarette Smoke In Vitro

    PubMed Central

    Mathis, Carole; Gebel, Stephan; Poussin, Carine; Belcastro, Vincenzo; Sewer, Alain; Weisensee, Dirk; Hengstermann, Arnd; Ansari, Sam; Wagner, Sandra; Peitsch, Manuel C; Hoeng, Julia

    2015-01-01

    To establish a relevant in vitro model for systems toxicology-based mechanistic assessment of environmental stressors such as cigarette smoke (CS), we exposed human organotypic bronchial epithelial tissue cultures at the air liquid interface (ALI) to various CS doses. Previously, we compared in vitro gene expression changes with published human airway epithelia in vivo data to assess their similarities. Here, we present a follow-up evaluation of these in vitro transcriptomics data, using complementary computational approaches and an integrated mRNA–microRNA (miRNA) analysis. The main cellular pathways perturbed by CS exposure were related to stress responses (oxidative stress and xenobiotic metabolism), inflammation (inhibition of nuclear factor-?B and the interferon gamma-dependent pathway), and proliferation/differentiation. Within post-exposure periods up to 48 hours, a transient kinetic response was observed at lower CS doses, whereas higher doses resulted in more sustained responses. In conclusion, this systems toxicology approach has potential for product testing according to “21st Century Toxicology”. PMID:25788831

  13. A NEW METHOD OF LONGITUDINAL DIARY ASSEMBLY FOR EXPOSURE MODELING

    EPA Science Inventory

    Many stochastic human exposure models require the construction of longitudinal time-activity diaries to evaluate the time sequence of concentrations encountered, and hence, the pollutant exposure for the simulated individuals. However, most of the available data on human activiti...

  14. Quasi-induced exposure: methodology and insight.

    PubMed

    Stamatiadis, N; Deacon, J A

    1997-01-01

    Even though the numerator in accident rates can be accurately determined nowadays, the denominator of these rates is an item of discussion and debate within the highway safety community. A critical examination of an induced exposure technique, based on the non-responsible driver/vehicle of a two-vehicle accident (quasi-induced exposure), is presented here. Differences in exposure for a series of accident location and time combinations are investigated, the assumption of similarities between drivers of single-vehicle accidents and the responsible driver of multiple-vehicle accidents is refuted, and the use of the non-responsible driver as a measure of exposure is tested using vehicle classification data. The results of the analyses reveal the following: (1) accident exposure is different for different location and time combinations: (2) induced exposure estimates provide an accurate reflection of exposure to multiple-vehicle accidents; (3) induced exposure estimates are acceptable surrogates for vehicle miles of travel when estimates are made for conditions during which the mix of road users is fairly constant; and (4) the propensity for involvement in single-vehicle accidents is generally different than that in multiple-vehicle accidents for a given class of road users. We concluded that the quasi-induced exposure is a powerful technique for measuring relative exposure of drivers or vehicles when real exposure data are missing. PMID:9110039

  15. Time exposure studies on stress corrosion cracking of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651, and titanium 6Al-4V

    NASA Technical Reports Server (NTRS)

    Terrell, J.

    1973-01-01

    The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651 and titanium 6Al-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 7) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity), and demineralized distilled water. Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, titanium stressed specimens showed no reactions to its environment. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 and aluminum 2014-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl), while aluminum 2219-T87 seem to resist stress corrosion cracking in sodium chloride at three levels of stress (25%, 50%, and 75% Y.S.). In organic fluids of methyl, ethyl, and iso-propyl alcohol, 2014-T6 and 7075-T651 did not fail by SCC; but 2014-T651 was susceptible to SCC in methly alcohol, but resistant in ethyl alcohol, iso-propyl alcohol and demineralized distilled water.

  16. Time exposure studies on stress corrosion cracking of aluminum 2014-T6, aluminum 7075-T651, and titanium 6Al-4V

    NASA Technical Reports Server (NTRS)

    Terrell, J.

    1972-01-01

    The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 7075-T651 and titanium 6A1-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 6) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity). Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, a similar observation was not noted for titanium stressed specimens. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl); while they (both alloys) seem to resist stress corrosion cracking in methyl alcohol, ethyl alcohol, iso-propyl alcohol, and demineralized distilled water. Titanium 6A1-4V showed some evidence of susceptibility to SCC in methanol, while no such susceptibility was exhibited in ethanol, iso-propyl alcohol and demineralized distilled water.

  17. Influence of gender and time diet exposure on endocrine pancreas remodeling in response to high fat diet-induced metabolic disturbances in mice.

    PubMed

    Oliveira, R B; Maschio, D A; Carvalho, C P F; Collares-Buzato, C B

    2015-07-01

    In this study, we investigated a possible sexual dimorphism regarding metabolic response and structural and functional adaptations of the endocrine pancreas after exposure to a high-fat diet (HFd). On chow diet, male and female C57BL/6/JUnib mice showed similar metabolic and morphometric parameters, except that female islets displayed a relatively lower ?-cell:non-?-cell ratio. After 30 days on HFd, both male and female mice showed increased weight gain, however only the males displayed glucose intolerance associated with high postprandial glycemia when compared to their controls. After 60 days on HFd, both genders became obese, hyperglycemic, hyperinsulinemic, insulin resistant and glucose intolerant, although the metabolic changes were more pronounced in males, while females displayed greater weight gain. In both genders, insulin resistance induced by HFd feeding was compensated by expansion of ?-cell mass without changes in islet cytoarchitecture. Interestingly, we found a strong correlation between the degree of ?-cell expansion and the levels of hyperglycemia in the fed state: male mice fed a 60d-HFd, showing higher glycemic levels also displayed a greater ?-cell mass increase in comparison with female mice. Additionally, sexual dimorphism was also observed regarding the source of ?-cell mass expansion following 60d-HFd: while in males, both hypertrophy and hyperplasia (revealed by morphometry and Ki67 immunoreaction) of ?-cells were observed, female islets displayed only a significant increase in ?-cell size. In conclusion, this study describes gender differences in metabolic response to high fat diet, paralleled by distinct compensatory morphometric changes in pancreatic islets. PMID:25819502

  18. Medium wave exposure characterisation using exposure quotients.

    PubMed

    Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Antolín, Alicia; Pinar, Iván

    2010-06-01

    One of the aspects considered in the International Commission on Non-Ionizing Radiation Protection guidelines is that, in situations of simultaneous exposure to fields of different frequencies, exposure quotients for thermal and electrical stimulation effects should be examined. The aim of the present work was to analyse the electromagnetic radiation levels and exposure quotients for exposure to multiple-frequency sources in the vicinity of medium wave radio broadcasting antennas. The measurements were made with a spectrum analyser and a monopole antenna. Kriging interpolation was used to prepare contour maps and to estimate the levels in the towns and villages of the zone. The results showed that the exposure quotient criterion based on electrical stimulation effects to be more stringent than those based on thermal effects or power density levels. Improvement of dosimetry evaluations requires the spectral components of the radiation to be quantified, followed by application of the criteria for exposure to multiple-frequency sources. PMID:20159912

  19. Antioxidative response of the three macrophytes Ceratophyllum demersum, Egeria densa, and Hydrilla verticillata to a time dependent exposure of cell-free crude extracts containing three microcystins from cyanobacterial blooms of Lake Amatitlán, Guatemala.

    PubMed

    Romero-Oliva, Claudia Suseth; Contardo-Jara, Valeska; Pflugmacher, Stephan

    2015-06-01

    Microcystins (MCs) produced by cyanobacteria in natural environments are a potential risk to the integrity of ecosystems. In this study, the effects of cyanobacterial cell-free crude extracts from a Microcystis aeruginosa bloom containing three MC-congeners MC-LR, -RR, and -YR at environmental relevant concentrations of 49.3±2.9, 49.8±5.9, and 6.9±3.8?g/L, respectively, were evaluated on Ceratophyllum demersum (L.), Egeria densa (Planch.), and Hydrilla verticillata (L.f.). Effects on photosynthetic pigments (total chlorophyll (chl), chl a, chl b, and carotenoids), enzymatic defense led by catalase (CAT), peroxidase (POD) and glutathione reductase (GR), and biotransformation enzyme glutathione S-transferase (GST) were measured after 1, 4, and 8h and after 1, 3, 7, and 14 days of exposure. Results show that in all exposed macrophytes, photosynthetic pigments were negatively affected. While chl a and total chl decreased with increasing exposure time, a parallel increase in chl b was observed after 8h. Concomitant increase of ?5, 16, and 34% of antioxidant carotenoid concentration in exposed C. demersum, E. densa, and H. verticillata, respectively, was also displayed. Enzymatic antioxidant defense systems in all exposed macrophytes were initiated within the first hour of exposure. In exposed E. densa, highest values of CAT and GR activities were observed after 4 and 8h, respectively, while in exposed H. verticillata highest value of POD activity was observed after 8h. An early induction with a significant increase of biotransformation enzyme GST was observed in E. densa after 4h and in C. demersum and H. verticillata after 8h. These results are the first to show rapid induction of stress and further possible MC biotransformation (based on the activation of GST enzymatic activity included in MC metabolization during the biotransformation mechanism) in macrophytes exposed to crude extract containing a mixture of MCs. PMID:25889089

  20. Personal exposure to ultrafine particles.

    PubMed

    Wallace, Lance; Ott, Wayne

    2011-01-01

    Personal exposure to ultrafine particles (UFP) can occur while people are cooking, driving, smoking, operating small appliances such as hair dryers, or eating out in restaurants. These exposures can often be higher than outdoor concentrations. For 3 years, portable monitors were employed in homes, cars, and restaurants. More than 300 measurement periods in several homes were documented, along with 25?h of driving two cars, and 22 visits to restaurants. Cooking on gas or electric stoves and electric toaster ovens was a major source of UFP, with peak personal exposures often exceeding 100,000 particles/cm³ and estimated emission rates in the neighborhood of 10¹² particles/min. Other common sources of high UFP exposures were cigarettes, a vented gas clothes dryer, an air popcorn popper, candles, an electric mixer, a toaster, a hair dryer, a curling iron, and a steam iron. Relatively low indoor UFP emissions were noted for a fireplace, several space heaters, and a laser printer. Driving resulted in moderate exposures averaging about 30,000 particles/cm³ in each of two cars driven on 17 trips on major highways on the East and West Coasts. Most of the restaurants visited maintained consistently high levels of 50,000-200,000 particles/cm³ for the entire length of the meal. The indoor/outdoor ratios of size-resolved UFP were much lower than for PM?.? or PM??, suggesting that outdoor UFP have difficulty in penetrating a home. This in turn implies that outdoor concentrations of UFP have only a moderate effect on personal exposures if indoor sources are present. A time-weighted scenario suggests that for typical suburban nonsmoker lifestyles, indoor sources provide about 47% and outdoor sources about 36% of total daily UFP exposure and in-vehicle exposures add the remainder (17%). However, the effect of one smoker in the home results in an overwhelming increase in the importance of indoor sources (77% of the total). PMID:20087407

  1. DEMONSTRATION OF HUMAN EXPOSURE TOOLS

    EPA Science Inventory

    The Human Exposure and Atmospheric Sciences Division (HEASD) of the National Exposure Research Laboratory (NERL) conducts research on exposure measurements, human activity patterns, exposure and dose models, and cumulative exposures critical for the Agency to make scientificall...

  2. Increasing the Time of Exposure to Aerosol Measles Vaccine Elicits an Immune Response Equivalent to That Seen in 9-Month-Old Mexican Children Given the Same Dose Subcutaneously

    PubMed Central

    García-León, Miguel Leonardo; Espinosa-Torres Torrija, Bogart; Hernández-Pérez, Brenda; Cardiel-Marmolejo, Lino E.; Beeler, Judy A.; Audet, Susette; Santos-Preciado, José Ignacio

    2011-01-01

    Background.?A 30-second aerosol measles vaccination successfully primes children 12 months of age and older but is poorly immunogenic when given to 9-month-old children. We examined the immune responses when increasing the duration to aerosol exposure in 9-month-olds. Methods.?One hundred and thirteen healthy 9-month-old children from Mexico City were enrolled; 58 received aerosol EZ measles vaccine for 2.5 minutes and 55 subcutaneously. Measles-specific neutralizing antibodies and cellular responses were measured before and at 3 and 6 months postimmunization. Results.?Adaptive immunity was induced in 97% after aerosol and 98% after subcutaneous administration. Seroconversion rates and GMCs were 95% and 373 mIU/mL (95% confidence interval [CI], 441–843) following aerosol vaccination and 91% and 306 mIU/mL (95% CI, 367–597) after subcutaneous administration at 3 months. The percentage of children with a measles-specific stimulation index ?3 was 45% and 60% in the aerosol versus 55% and 59% in the subcutaneous group at 3 and 6 months, respectively. CD8 memory cell frequencies were higher in the aerosol group at 3 months compared with the subcutaneous group. Adverse reactions were comparable in both groups. Conclusions.?Increasing exposure time to aerosol measles vaccine elicits immune responses that are comparable to those seen when an equivalent dose is administered by the subcutaneous route in 9-month-old infants. PMID:21742842

  3. Time course and manner of Purkinje neuron death following a single ethanol exposure on postnatal day 4 in the developing rat

    Microsoft Academic Search

    K. E Light; S. M Belcher; D. R Pierce

    2002-01-01

    The present study was designed to evaluate the time course and manner of Purkinje cell death following a single ethanol dose delivered intragastrically on postnatal day (PN) 4 to rat pups. Analysis included immunolabeling of Purkinje cells with antibody specific for calbindin D28k and counting of Purkinje cells in each lobule of a mid-vermal slice. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end

  4. The influence of time of maternal exposure to 2,4,5,2 prime ,4 prime ,5 prime -hexachlorobiphenyl on its accumulation in their nursing offspring

    Microsoft Academic Search

    L. A. Gallenberg; B. J. Ring; M. J. Vodicnik

    1990-01-01

    2,4,5,2',4',5'-Hexachlorobiphenyl (6-CB) is mobilized from rodent tissues during the lipid depletion associated with food restriction or lactation, the latter condition resulting in the substantial elimination of the maternal body burden of the chemical to nursing offspring. The present study was undertaken to determine whether the rate and\\/or magnitude of accumulation of 6-CB in nursing offspring differed with time following PCB

  5. Influence of extended light exposure curing times on the degree of conversion of resin-based pit and fissure sealant materials

    PubMed Central

    Fatima, Nazish

    2014-01-01

    Purpose The aim of present study was to evaluate extended curing times on the degree of conversion (DC) of filled and unfilled resin-based materials used as pit and fissure sealants. Materials and methods The materials examined were a flowable composite (Filtek™ Z350 XT Flowable) and a pit and fissure sealant (Clinpro™ Sealant). Thirty disks of each material were prepared. The 30 made of the flowable composite were divided into three groups (n = 10 each) according to the three different curing times studied: 20 s (group 1), 40 s (group 2), and 60 s (group 3). Similarly, the 30 disks made of the pit and fissure sealant were divided into three groups (n = 10 each) according to the three different curing times: 20 s (group 4), 40 s (group 5), and 60 s (group 6). After polymerization, the disks were removed from the mold and stored in dry, lightproof containers in an incubator at 37 °C for 24 h. The DC was obtained using an Avatar 320 FTIR spectrometer. Then the data were analyzed using the Kruskal–Wallis test and the Fisher’s least significant difference post hoc test for multiple comparisons (alpha = 0.05). Results DC values for the flowable composite (Filtek™ Z350 XT) were higher (p = 0.002) than those for the pit and fissure sealant (Clinpro™ Sealant). Group 2 and group 5 showed significantly higher DC values than group 1 and group 4, respectively. There was no difference between groups 2 and 3 or between groups 5 and 6 (p = 2.93). Conclusion An extended curing time improves the DC to some extent for both materials. PMID:25382947

  6. Solvent exposures in screen printing shops.

    PubMed

    Horstman, S W; Browning, S R; Szeluga, R; Burzycki, J; Stebbins, A

    2001-01-01

    A comprehensive description of working conditions, exposure patterns for organic solvents, and related health symptoms among workers in ten small screen printing companies located in Seattle, Washington, is presented. Sampling methods included continuous area monitoring, grab sampling, personal sampling, and time study observation. A total of 27 workers were observed and monitored for solvent exposure. Short-term peak exposures were characterized in terms of magnitude, duration and repetition, and their contribution to time weighted average (TWA) exposures were evaluated. A health questionnaire addressing the symptoms potentially attributable to solvents was used to investigate the possible health effects from exposure. Significant differences in the prevalence of headaches, dizziness, intoxication, and dry skin (p < 0.01) were reported among workers who had some solvent exposure compared with the referent group that was not exposed. Exposed workers were also more likely to report fatigue, loss of strength in the arms and hands, difficulty concentrating, sore throat, and a low alcohol tolerance. The study documented highly variable levels of solvent exposures. Screen printing workers in different companies, while performing the same basic tasks, had time weighted average (TWA) exposures ranging from 2% to 100% of the recommended threshold limit value (TLV) for mixtures. Continuous monitoring indicated that high short-term exposures are responsible for the bulk of TWA exposures. Grab samples and continuous monitoring verified that recommended Short Term Exposure Limits (STEL) for individual solvents may be exceeded on a routine basis. Frequent skin contact with solvents was also observed. Health problems in this industry and other small industries using organic solvents may result from these complex patterns of exposure. PMID:11759907

  7. IDENTIFYING CRITICAL WINDOWS OF EXPOSURE FOR CHILDREN'S HEALTH

    EPA Science Inventory

    Several authors have considered the importance of exposure timing and how this affects the outcomes observed, but no one has systematically compiled preconceptional, prentatal, and postnatal developmental exposures and subsequent outcomes. Efforts were undertaken to examine the ...

  8. CHARACTERIZATION OF RESIDENTIAL EXPOSURE TO CHLORPYRIFOS AND DIAZINON

    EPA Science Inventory

    Exposures to chlorpyrifos and diazinon in residential microenvironment in AZ were estimated using the indirect method of exposure calculation by combining measured concentrations in multiple media with time subjects spent indoors, dietary and non-dietary items they consumed, an...

  9. Isoflurane Exposure Monitoring Policy Procedure: 6. 14

    E-print Network

    Jia, Songtao

    (NIOSH) guidelines for exposure minimization, with a Time Weighted Average (TWA) of 2 ppm for the period. Recordkeeping EH&S will keep all exposure monitoring results. I. Appendices N/A J. Forms N/A K. References NIOSH: Waste Anesthetic Gases-Occupational Hazards in Hospitals http://www.cdc.gov/niosh/docs/2007-151/ #12;

  10. Preschool Teachers' Exposure to Classroom Noise

    ERIC Educational Resources Information Center

    Grebennikov, Leonid

    2006-01-01

    This research examined exposure to classroom noise of 25 full-time teaching staff in 14 preschool settings located across Western Sydney. The results indicated that one teacher exceeded the maximum permissible level of daily noise exposure for employees under the health and safety legislation. Three staff approached this level and 92% of teachers…

  11. Time and Cell Type Dependency of Survival Responses in Co-cultured Tumor and Fibroblast Cells after Exposure to Modulated Radiation Fields.

    PubMed

    Butterworth, Karl T; McMahon, Stephen J; McKee, Jamie C; Patel, Gaurang; Ghita, Mihaela; Cole, Aidan J; McGarry, Conor K; O'Sullivan, Joe M; Hounsell, Alan R; Prise, Kevin M

    2015-06-01

    Advanced radiotherapy techniques such as intensity-modulated radiation therapy (IMRT) achieve high levels of conformity to the target volume through the sequential delivery of highly spatially and temporally modulated radiation fields, which have been shown to impact radiobiological response. This study aimed to characterize the time and cell type dependency of survival responses to modulated fields using single cell type (SCT) and mixed cell type (MCT) co-culture models of transformed fibroblast (AG0-1522b) cells, prostate (DU-145) and lung (H460) cancer cells. In SCT cultures, in-field responses showed no significant time dependency while out-of-field responses occurred early, and plateaued 6 h after irradiation in both DU-145 and H460 cells. Under modulated beam configurations MCT co-cultures showed cell-specific, differential out-of-field responses depending on the irradiated in-field and responding out-of-field cell type. The observed differential out-of-field responses may be due to the genetic background of the cells, in particular p53 status, which has been shown to mediate radiation-induced bystander effects (RIBEs). These data provide further insight into the radiobiological parameters that influence out-of-field responses, which have potential implications for advanced radiotherapy modalities and may provide opportunities for biophysical optimization in radiotherapy treatment planning. PMID:25973952

  12. Time-dependent changes in antioxidative enzyme expression and photosynthetic activity of Chlamydomonas reinhardtii cells under acute exposure to cadmium and anthracene.

    PubMed

    Aksmann, Anna; Pokora, Wojciech; Ba?cik-Remisiewicz, Agnieszka; Dettlaff-Pokora, Agnieszka; Wielgomas, Bartosz; Dziadziuszko, Ma?gorzata; Tukaj, Zbigniew

    2014-12-01

    Heavy metals (HM) and polycyclic aromatic hydrocarbons (PAHs) are present in the freshwater environment at concentrations that can be hazardous to the biota. Among HMs and PAHs, cadmium (Cd) and anthracene (ANT) are the most prevalent and toxic ones. The response of Chlamydomonas cells to Cd and ANT at concentrations that markedly reduced the growth of algal population was investigated in this study. At such concentrations, both cadmium and anthracene were recognized as oxidative stress inducers, since high concentration of H2O2 in treated cultures was observed. Therefore, as a part of the "molecular phase" of the cell response to this stress, we examined the time-dependent expression of genes encoding the main antioxidative enzymes: superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), as well as the activity of these enzymes in cells, with special attention paid to chloroplastic and mitochondrial isoforms of SOD. To characterize the cell response at the "physiological level", we examined the photosynthetic activity of stressed cells via analysis of chlorophyll a fluorescence in vivo. In contrast to standard ecotoxicity studies in which the growth end-points are usually determined, herein we present time-dependent changes in algal cell response to Cd- and ANT-induced stress. The most significant effect(s) of the toxicants on photosynthetic activity was observed in the 6th hour, when strong depression of PI parameter value, an over 50 percent reduction of the active reaction center fraction (RC0) and a 3-fold increase in non-photochemical energy dissipation (DI0/RC) were noted. At the same time, the increase (up to 2.5-fold) in mRNA transcript of SOD and CAT genes, followed by the enhancement in the enzyme activity was observed. The high expression of the Msd 3 gene in treated Chlamydomonas cells probably complements the partial loss of chloroplast Fe-SOD and APX activity, while catalase and Mn-SOD 5 seem to be the major enzymes responsible for mitochondrion protection. The progressive increase in SOD and CAT activities seems to be involved in the recovery of photosynthesis within 12-24h after the application of the toxicants. PMID:25193882

  13. Integrated Exposure Assessment Monitoring.

    ERIC Educational Resources Information Center

    Behar, Joseph V.; And Others

    1979-01-01

    Integrated Exposure Assessment Monitoring is the coordination of environmental (air, water, land, and crops) monitoring networks to collect systematically pollutant exposure data for a specific receptor, usually man. (Author/BB)

  14. EPIDEMIOLOGY AND EXPOSURE ASSESSMENT

    EPA Science Inventory

    Research collaborations between the National Health and Environmental Effects Research Laboratory (NHEERL) and the National Exposure Research Laboratory (NERL) centered on the development and application of exposure analysis tools in environmental epidemiology include the El Paso...

  15. Occupational Noise Exposure

    MedlinePLUS

    ... reduce worker exposure to noise in a workplace. Engineering controls that reduce sound exposure levels are available and technologically feasible for most noise sources. Engineering controls involve modifying or replacing equipment, or making ...

  16. Exposure Analysis Modeling System

    EPA Science Inventory

    The Exposure Analysis Modeling System (EXAMS) is an interactive software application for formulating aquatic ecosystem models and evaluating the fate, transport, and exposure concentrations of synthetic organic chemicals including pesticides, industrial materials, and leachates f...

  17. CHAPTER ONE: EXPOSURE MEASUREMENTS.

    EPA Science Inventory

    Determining human exposure to suspended particualte concentrations requires measurements that quantify different particle properties in microenvironments where people live, work, and play. Particle mass, size, and chemical composition are important exposure variables, and these ...

  18. Analysis of a new fluoroquinolone derivative (Q-35) in human scalp hair as an index of drug exposure and as a time marker in hair.

    PubMed

    Uematsu, T; Ohsawa, Y; Mizuno, A; Nakashima, M

    1994-01-01

    Scalp hair samples were obtained every month for three months after administration from healthy male volunteers who participated in the phase I study of a new antimicrobial fluoroquinolone derivative (Q-35). Hairs were cut into 1 cm long pieces successively from the scalp end. Corresponding pieces of 5 hair strands were dissolved in 1 M NaOH and assessed for Q-35 by HPLC. The drug was detectable in the hairs of all subjects taking either a single (400 mg, n = 6) or repeated oral doses of Q-35 (400 mg/day for 6.5 days, total 2600 mg, n = 6). The hair portions containing the drug were shown in most subjects to move outwards along the hair shafts month by month in proportion to the hair growth rate of about 1 cm/month. Q-35 (600 mg/day) was also given to 6 healthy male volunteers for 6.5 days (total 3900 mg) and hair samples were obtained 1 and 3 months after administration. When Q-35 was analyzed along a single hair shaft, the drug was detectable only in 1-2 consecutive 1 cm long pieces, which were also shown to move outwards along the hair shaft with time. A detailed analysis revealed that the drug was contained only in 2-4 consecutive 2.5 mm long pieces of a single hair collected after 3 months, showing that there was no significant axial diffusion of the drug along the hair shaft with time.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8068569

  19. Swimmer Exposure Assessment Model

    EPA Science Inventory

    The SWIMODEL is a screening tool for conducting an exposure assessment of pesticides found in indoor swimming pools and spas. The SWIMODEL uses well-accepted screening exposure assessment equations to calculate the total worst-case exposure for swimmers expressed as a mass-based...

  20. Opioid Antagonist Impedes Exposure.

    ERIC Educational Resources Information Center

    Merluzzi, Thomas V.; And Others

    1991-01-01

    Thirty spider-phobic adults underwent exposure to 17 phobic-related, graded performance tests. Fifteen subjects were assigned to naltrexone, an opioid antagonist, and 15 were assigned to placebo. Naltrexone had a significant effect on exposure, with naltrexone subjects taking significantly longer to complete first 10 steps of exposure and with…

  1. DIETARY EXPOSURE MEASUREMENTS

    EPA Science Inventory

    This research constitutes the MCEARD base dietary exposure research program and is conducted to complement the NERL total human exposure program. The research builds on previous work to reduce the level of uncertainty in exposure assessment by improving NERL's ability to evaluat...

  2. GUIDELINES FOR EXPOSURE ASSESSMENT

    EPA Science Inventory

    The Guidelines for Exposure Assessment describe the general concepts of exposure assessment including definitions and associated units, and by providing guidance on the planning and conducting of an exposure assessment. Guidance is also provided on presenting the results of the e...

  3. HUMAN EXPOSURE ACTIVITY PATTERNS

    EPA Science Inventory

    Human activity/uptake rate data are necessary to estimate potential human exposure and intake dose to environmental pollutants and to refine human exposure models. Personal exposure monitoring studies have demonstrated the critical role that activities play in explaining and pre...

  4. Biological Response to SPE Exposures

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Cucinotta, F. A.; Kim, M.; Shinn, J. L.; Jones, T. D.; Chang, C. K.

    2004-01-01

    It has long been recognized that a single solar particle event (SPE) can produce, over a short period of time, exposures on the order of LD50 for humans under normal physiological conditions. It is further recognized that recovery from injury over the period of exposure would greatly increase the chances of survival (dose rate effects) although such effects were left unquantified. In the present report we use the bioresponse model derived from a broad range of animal and human exposure data for evaluation of troop readiness in tactical nuclear warfare to evaluate the biological risk posed by the solar event of 4 August 1972. The astronaut blood forming organ (BFO) exposure in deep space would have been 2.2 Sv (1.6 Gy) in a space suit, 1.8 Sv (1.3 Gy) in an aluminum pressure vessel, and 0.7 Sv (0.5 Gy) in an equipment room compared to an X-ray mortality threshold of 1.5 Gy (assuming high dose rate). We find BFO dose rate effectiveness factors for this SPE on the order of 3 to 4, greatly reducing the mortality risks for this event. There is an approximate 3 percent chance that an even larger event may occur for which exposures could be 2-4 times higher. Assured survival of the astronaut requires added shelter shielding and a warning system for this event. The required mass of the shelter shield can be greatly reduced by using hydrogenous materials such as polymers, water, food, and other biological materials in its construction. Limitations of the current bioresponse model arise from the exposures taking place in the microgravity environment wherein the immune system is already challenged and the effective mortality threshold may be reduced by a factor of two. Such microgravity effects could greatly affect astronaut risks.

  5. Occupational infectious disease exposures in EMS personnel.

    PubMed

    Reed, E; Daya, M R; Jui, J; Grellman, K; Gerber, L; Loveless, M O

    1993-01-01

    Reports of occupationally transmitted hepatitis B virus (HBV) and human immunodeficiency virus (HIV) prompted the Portland Bureau of Fire Rescue and Emergency Services (PFB) to institute a comprehensive program for handling and tracking on-the-job infectious disease exposures. Data were collected for a 2-year period beginning January 1, 1988, and ending December 31, 1989, utilizing verbal and written exposure reports, prehospital care reports, and PFB statistical information. Two hundred and fifty-six (256) exposures were categorized. The overall incidence of reported exposure was 4.4/1,000 emergency medical service (EMS) calls. Of these exposures, 14 (5.5%) were needle sticks, 15 (5.9%) were eye splashes, 8 (3.1%) were mucous membrane exposures, 38 (14.8%) were exposure to nonintact skin, 120 (46.9%) were exposures to intact skin, and 61 (23.8%) involved respiratory exposure only. The incidence of exposure of nonintact skin or mucous membranes to blood or body fluids and needle sticks was 1.3/1,000 EMS calls. Forty-eight individuals (64% of those incurring needle sticks, or exposure of non-intact skin or mucous membranes to blood or body fluids) were treated and followed for signs of infection. Of this group, 11 individuals (26%) previously vaccinated against hepatitis B demonstrated inadequate HBsAb titers at the time of exposure. Requests for HIV and HBV information on source patients were made for needle sticks or exposure of nonintact skin or mucous membranes to blood or high-risk body fluids. Information on the source patient's HIV status was obtained for 57% of these requests.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8445190

  6. Reduction of sister chromatid exchange frequency with time after mutagen exposure in Chinese hamster ovary cells in the presence of 3-aminobenzamide

    SciTech Connect

    Schwartz, J.L.; Morgan, W.F.; Wolff, S.

    1984-01-01

    3-Aminobenzamide (3AB) is a potent inhibitor of poly(ADP-ribose) synthesis and has been reported to inhibit DNA repair. Inhibition of poly(ADP-ribose) synthesis by 3AB results in a potentiation of the cytotoxic effects of alkylating agents and synergistically increases the frequency of sister chromatid exchanges (SCEs) induced in Chinese hamster ovary cells by methyl methanesulfonate (MMS). Experiments were carried out to determine if this synergism was related to an inhibition of the repair or the removal of SCE-forming lesions by 3AB. Cells were treated with MMS or ethyl nitrosourea (ENU) and either held in a nonproliferative state or maintained in exponential growth for up to 48 hr before SCE frequencies were measured. During this time, the SCE frequency decreased greatly. 3AB did not affect this decrease in either cycling or noncycling cells. Furthermore, 3AB appears to exert its effect only in cycling cells when bromodeoxyuridine is present. Therefore, the synergism between 3AB and alkylating agents in the induction of SCEs is unrelated to effects of 3AB on the repair or removal of SCE-forming lesions.

  7. The influence of time of maternal exposure to 2,4,5,2 prime ,4 prime ,5 prime -hexachlorobiphenyl on its accumulation in their nursing offspring

    SciTech Connect

    Gallenberg, L.A.; Ring, B.J.; Vodicnik, M.J. (Medical College of Wisconsin, Milwaukee (USA))

    1990-06-01

    2,4,5,2',4',5'-Hexachlorobiphenyl (6-CB) is mobilized from rodent tissues during the lipid depletion associated with food restriction or lactation, the latter condition resulting in the substantial elimination of the maternal body burden of the chemical to nursing offspring. The present study was undertaken to determine whether the rate and/or magnitude of accumulation of 6-CB in nursing offspring differed with time following PCB administration to the maternal animal. Female ICR mice were administered two doses of 6-CB. Group I animals received (14C)-6-CB as weanlings (15-20 g) followed by unlabeled 6-CB 5 weeks later, after mating, on Day 1 of gestation. Group II received unlabeled 6-CB as weanlings and (14C)-6-CB on Day 1 of gestation. Thus, 14C identified the mobilization and elimination of either the first or the second dose of 6-CB in the treatment groups (I = (14C)-6-CB, 6-CB; II = 6-CB, (14C)-6-CB). Both groups of animals retained approximately 80% of the administered radiolabeled dose. The tissue distribution of (14C)-6-CB in group II as a percentage of the body burden was not different from that in group I as determined from maternal tissue concentrations on Day 14 of gestation. The percentage of the maternal body burden of (14C)-6-CB accumulated in suckling offspring of group II mothers was significantly greater than that in group I offspring on Day 1 (I, 2.2 +/- 0.5%; II, 3.5 +/- 0.4%), Day 3 (I, 14.8 +/- 1.9%; II, 24.6 +/- 2.7%), Day 5 (I, 16.8 +/- 1.4%; II, 24.8 +/- 0.8%), and Day 12 (I, 32.3 +/- 0.5%; II, 45.5 +/- 1.7%) postpartum. This differential elimination was reflected in the t1/2 of elimination of the radiolabeled dose from parametrial fat during lactation, which was significantly longer in group I (14 days) than group II maternal animals (9 days).

  8. Neonatal ethanol exposure results in dose-dependent impairments in the acquisition and timing of the conditioned eyeblink response and altered cerebellar interpositus nucleus and hippocampal CA1 unit activity in adult rats

    PubMed Central

    Lindquist, Derick H.; Sokoloff, Greta; Milner, Eric; Steinmetz, Joseph E.

    2013-01-01

    Exposure to ethanol in neonatal rats results in reduced neuronal numbers in the cerebellar cortex and deep nuclei of juvenile and adult animals. This reduction in cell numbers is correlated with impaired delay eyeblink conditioning (EBC), a simple motor learning task in which a neutral conditioned stimulus (CS; tone) is repeatedly paired with a co-terminating unconditioned stimulus (US; periorbital shock). Across training, cell populations in the interpositus (IP) nucleus model the temporal form of the eyeblink conditioned response (CR). The hippocampus, though not required for delay EBC, also shows learning-dependent increases in CA1 and CA3 unit activity. In the present study, rat pups were exposed to 0, 3, 4, or 5 mg/kg/day of ethanol during postnatal days (PD) 4–9. As adults, CR acquisition and timing were assessed during 6 training sessions of delay EBC with a short (280 msec) interstimulus interval (ISI; time from CS onset to US onset) followed by another 6 sessions with a long (880 msec) ISI. Neuronal activity was recorded in the IP and area CA1 during all 12 sessions. The high-dose rats learned the most slowly and, with the moderate-dose rats, produced the longest CR peak latencies over training to the short ISI. The low dose of alcohol impaired CR performance to the long ISI only. The 3E (3 mg/kg/day of ethanol) and 5E (5 mg/kg/day of ethanol) rats also showed slower-than-normal increases in learning-dependent excitatory unit activity in the IP and CA1. The 4E (4 mg/kg/day of ethanol) rats showed a higher rate of CR production to the long ISI and enhanced IP and CA1 activation when compared to the 3E and 5E rats. The results indicate that binge-like ethanol exposure in neonatal rats induces long-lasting, dose-dependent deficits in CR acquisition and timing and diminishes conditioning-related neuronal excitation in both the cerebellum and hippocampus. PMID:23871534

  9. Reconstruction of occupational mercury exposures at a chloralkali plant

    PubMed Central

    Williams, P; Frumkin, H; Pierce, M; Manning, C; Elon, L; Sanders, A

    2001-01-01

    OBJECTIVE—To reconstruct historical workplace exposure to mercury (Hg) from 1956 to 1994 at a large chloralkali factory for use in a current epidemiology study of the factory.?METHODS—All job activities of the employees were classified into one of 16 exposure categories, and the dates of changes in the processes were identified. Exposures to Hg for each job category, at each period of the plant's operation, were then reconstructed from several data sources. A job-time period-exposure matrix was created, and the individual exposures of former workers were calculated. Data on exposure to Hg in air were compared with modelled concentrations of Hg in air and data on urinary Hg of the employees.?RESULTS—Within an exposure category, concentrations of Hg in air were fairly constant for the first 20 years of the factory's operation, but began to increase in the late 1970s. Employees working in the cell room had the greatest exposures to Hg. The exposure estimates had significant correlations (p<0.001) with the urinary data and were well within the modelled range of concentrations of Hg in air.?CONCLUSIONS—The highest exposures occurred from 1987 until the plant closed in early 1994 with some exposure categories having time weighted average exposures to Hg greater than 140 µg/m3.???Keywords: mercury; chloralkali; occupational exposure; job exposure matrix PMID:11160985

  10. EXAMPLE EXPOSURE SCENARIOS ASSESSMENT TOOL

    EPA Science Inventory

    Exposure scenarios are a tool to help the assessor develop estimates of exposure, dose, and risk. An exposure scenario generally includes facts, data, assumptions, inferences, and sometimes professional judgment about how the exposure takes place. The human physiological and beh...

  11. Loud noise exposure and acoustic neuroma.

    PubMed

    Fisher, James L; Pettersson, David; Palmisano, Sadie; Schwartzbaum, Judith A; Edwards, Colin G; Mathiesen, Tiit; Prochazka, Michaela; Bergenheim, Tommy; Florentzson, Rut; Harder, Henrik; Nyberg, Gunnar; Siesjö, Peter; Feychting, Maria

    2014-07-01

    The results from studies of loud noise exposure and acoustic neuroma are conflicting. A population-based case-control study of 451 acoustic neuroma patients and 710 age-, sex-, and region-matched controls was conducted in Sweden between 2002 and 2007. Occupational exposure was based on historical measurements of occupational noise (321 job titles summarized by a job exposure matrix) and compared with self-reported occupational noise exposure. We also evaluated self-reported noise exposure during leisure activity. Conditional logistic regression was used to estimate odds ratios. There was no statistically significant association between acoustic neuroma and persistent occupational noise exposure, either with or without hearing protection. Exposure to loud noise from leisure activity without hearing protection was more common among acoustic neuroma cases (odds ratio = 1.47, 95% confidence interval: 1.06, 2.03). Statistically significant odds ratios were found for specific leisure activities including attending concerts/clubs/sporting events (odds ratio = 1.82, 95% confidence interval: 1.09, 3.04) and participating in workouts accompanied by loud music (odds ratio = 2.84, 95% confidence interval: 1.37, 5.89). Our findings do not support an association between occupational exposure to loud noise and acoustic neuroma. Although we report statistically significant associations between leisure-time exposures to loud noise without hearing protection and acoustic neuroma, especially among women, we cannot rule out recall bias as an alternative explanation. PMID:24786799

  12. Dimethylacetamide pharmacokinetics following inhalation exposures to rats and mice.

    PubMed

    Hundley, S G; Lieder, P H; Valentine, R; McCooey, K T; Kennedy, G L

    1994-09-01

    Whole-body inhalation exposures to N,N-dimethylacetamide (DMAC) were conducted with male rats (Crl:CD BR) and mice (Crl:CD-1 (ICR)BR). Exposure concentrations were 50, 150, 300 and 500 ppm. The exposure routines consisted of single 1-, 3-, or 6-h exposures and ten 6-h exposures (10 exposure days in 2 weeks). Area under the plasma concentration curve (AUC) values were determined for DMAC and its metabolite N-methylacetamide (NMAC), following 6-h exposures (single exposure or last in a series of 10 exposures). The range of exposures was chosen to assess the exposure-dependent nature of DMAC pharmacokinetics in rats and mice. Plasma profiles indicated mice metabolized DMAC rapidly with plasma half-lives from 0.3 to 0.5 h for DMAC. The DMAC AUC values from mice were underestimated due to the required time (< 30 min) between termination of exposure and the initial blood sample. DMAC plasma half-life in rats ranged from 0.6 to 1.5 h. The AUC values for DMAC in rats increased approximately 5-fold and 3-fold as exposure concentrations increased from 150 to 300 ppm and 300 to 500 ppm, respectively. NMAC persisted in plasma for at least 24 h after the 150, 300 and 500 ppm exposures to rats. NMAC was not detected in plasma from mice beyond the 12-h post-exposure timepoint for the 300 and 500 ppm exposures. Regardless of exposure level, repeated DMAC exposures to both rats and mice resulted in plasma profiles of DMAC and NMAC similar to those from a single exposure. The dose-dependent nature of the DMAC AUC data and the absence of effects of repeated 300 and 500 ppm DMAC exposures supported a toxicity-driven upper limit of 350 ppm for a chronic inhalation study. PMID:8091430

  13. Coded exposure photography: motion deblurring using fluttered shutter

    Microsoft Academic Search

    Ramesh Raskar; Amit K. Agrawal; Jack Tumblin

    2006-01-01

    In a conventional single-exposure photograph, moving objects or moving cameras cause motion blur. The exposure time defines a temporal box filter that smears the moving object across the image by convolution. This box filter destroys important high-frequency spatial details so that deblurring via deconvolution becomes an ill- posed problem. Rather than leaving the shutter open for the entire exposure du-

  14. Modeling community asbestos exposure near a vermiculite processing facility: Impact of human activities on cumulative exposure.

    PubMed

    Adgate, John L; Cho, Sook Ja; Alexander, Bruce H; Ramachandran, Gurmurthy; Raleigh, Katherine K; Johnson, Jean; Messing, Rita B; Williams, A L; Kelly, James; Pratt, Gregory C

    2011-01-01

    Contaminated vermiculite ore from Libby, Montana was processed in northeast Minneapolis from 1936 to 1989 in a densely populated urban residential neighborhood, resulting in non-occupational exposure scenarios from plant stack and fugitive emissions as well as from activity-based scenarios associated with use of the waste rock in the surrounding community. The objective of this analysis was to estimate potential cumulative asbestos exposure for all non-occupationally exposed members of this community. Questionnaire data from a neighborhood-exposure assessment ascertained frequency of potential contact with vermiculite processing waste. Monte Carlo simulation was used to develop exposure estimates based on activity-based concentration estimates and contact durations for four scenarios: S1, moved asbestos-contaminated waste; S2, used waste at home, on lawn or garden; S3, installed/removed vermiculite insulation; S4, played in or around waste piles at the plant. The simulation outputs were combined with air-dispersion model results to provide total cumulative asbestos exposure estimates for the cohort. Fiber emissions from the plant were the largest source of exposure for the majority of the cohort, with geometric mean cumulative exposures of 0.02 fibers/cc × month. The addition of S1, S2 and S3 did not significantly increase total cumulative exposure above background exposure estimates obtained from dispersion modeling. Activity-based exposures were a substantial contributor to the upper end of the exposure distribution: 90th percentile S4 exposure estimates are ?10 times higher than exposures from plant emissions. Pile playing is the strongest source of asbestos exposure in this cohort, with other activity scenarios contributing less than from plant emissions. PMID:21343955

  15. Biomarkers of xenobiotic exposures

    SciTech Connect

    Brewster, M.A.

    1988-07-01

    Direct measurement of xenobiotic (foreign) chemicals is not always feasible as an exposure assessment,--owing to rapid metabolism, sequestration into fatty tissues, or lack of suitable assay methods. Furthermore, suspect exposures often involve complex mixtures of organics. In these circumstances, indirect biomarkers of exposure can be most helpful. This paper reviews four urinary parameters that hold promise as biomarkers of exposure in occupational and environmental settings: glucaric acid (end-product of the glucuronidation pathway), thioethers (end-product of glutathione reaction with electrophilic or alkylating agents), porphyrin pattern (altered with disruption in heme biosynthesis), and the Ames mutagenicity test. 112 references.

  16. Short Time Exposure (STE) test in conjunction with Bovine Corneal Opacity and Permeability (BCOP) assay including histopathology to evaluate correspondence with the Globally Harmonized System (GHS) eye irritation classification of textile dyes.

    PubMed

    Oliveira, Gisele Augusto Rodrigues; Ducas, Rafael do Nascimento; Teixeira, Gabriel Campos; Batista, Aline Carvalho; Oliveira, Danielle Palma; Valadares, Marize Campos

    2015-09-01

    Eye irritation evaluation is mandatory for predicting health risks in consumers exposed to textile dyes. The two dyes, Reactive Orange 16 (RO16) and Reactive Green 19 (RG19) are classified as Category 2A (irritating to eyes) based on the UN Globally Harmonized System for classification (UN GHS), according to the Draize test. On the other hand, animal welfare considerations and the enforcement of a new regulation in the EU are drawing much attention in reducing or replacing animal experiments with alternative methods. This study evaluated the eye irritation of the two dyes RO16 and RG19 by combining the Short Time Exposure (STE) and the Bovine Corneal Opacity and Permeability (BCOP) assays and then comparing them with in vivo data from the GHS classification. The STE test (first level screening) categorized both dyes as GHS Category 1 (severe irritant). In the BCOP, dye RG19 was also classified as GHS Category 1 while dye RO16 was classified as GHS no prediction can be made. Both dyes caused damage to the corneal tissue as confirmed by histopathological analysis. Our findings demonstrated that the STE test did not contribute to arriving at a better conclusion about the eye irritation potential of the dyes when used in conjunction with the BCOP test. Adding the histopathology to the BCOP test could be an appropriate tool for a more meaningful prediction of the eye irritation potential of dyes. PMID:26026500

  17. Human occupational and nonoccupational exposure to fibers.

    PubMed Central

    Esmen, N A; Erdal, S

    1990-01-01

    Human exposure to fibers in occupational and nonoccupational environments has been a health concern for nearly a century. In this review, selected results from the literature are presented to highlight the availability, limitations, and interpretive difficulties associated with the past and current human fiber exposure data sets. In the traditionally defined asbestos fibers, large amounts of the data available suffer from the diversity of sample collection and analysis methods. Two simple generalizations suggest that occupational exposures are several orders of magnitude higher than that of environmental exposures; and currently extant data and the current routine measurement practices present significant difficulties in the consistent interpretation of the data with respect to health effects. The data on the human exposures to man-made vitreous fibers are much more complete than the data on asbestos exposure, while exposure data on other man-made fibrous materials are lacking. The human exposure data to many minerals which, at times, exist in fibrous habit, are very scanty, and in view of the biological activity of some of these fibers, this lack may be of significant concern. PMID:2272324

  18. Formaldehyde exposure and acute health effects study

    SciTech Connect

    Quackenboss, J.J.; Lebowitz, M.D.; Michaud, J.P.; Bronnimann, D. (Univ. of Arizona Health Sciences Center, Tucson (USA))

    1989-01-01

    To assess the effects of formaldehyde exposures on health, exposure groups were defined using baseline exposure and health questionnaires. Formaldehyde concentrations were poorly correlated with these exposure classifications, perhaps due to the time delay between classification and monitoring. The 151 households reported here had a mean HCHO concentration of 35 (S.E. 1.5 and median 30) {mu}g/m{sup 3}. Passive samplers prepared in our lab were calibrated in a chamber to derive an estimated sampling rate of 0.311 {mu}g/(mg {center dot} m{sup {minus}3} {center dot} hr). They were also compared to commercially available samplers inside of the homes, with a correlation coefficient of 0.896 and mean difference of 2.6 {mu}g/m{sup 3}. In this report of initial findings from an ongoing study, daily symptoms and peak expiratory flow measurements were compared with an HCHO exposure classification based on the median measured concentrations. None of the symptoms groups were related to HCHO exposure when controlling for age and sex. There was a significant relationship between HCHO exposure and variability in peak expiratory flows that was dependent on age group. It may be especially important to assess the variability in reactive individuals and children to determine the short-term effects of HCHO exposures and possible long-term consequences.

  19. Reference Gene Selection for Quantitative Real-Time RT-PCR Normalization in the Half-Smooth Tongue Sole (Cynoglossus semilaevis) at Different Developmental Stages, in Various Tissue Types and on Exposure to Chemicals

    PubMed Central

    Liu, Conghui; Xin, Nian; Zhai, Yi; Jiang, Liming; Zhai, Jieming; Zhang, Quanqi; Qi, Jie

    2014-01-01

    Quantitative real time RT-PCR has been described as the most sensitive method for the detection of low abundance mRNA. To date, no reference genes have been screened in the half-smooth tongue sole (Cynoglossus semilaevis). The aim of this study was to select the most stable genes for quantitative real-time RT-PCR. Eight housekeeping genes (18S, TUBA, B2M, ACTB, EF1A, GAPDH, RPL17 and UBCE) were tested at different developmental stages, in different tissues, and following exposure to the drug SB-431542. Using geNorm, BestKeeper and NormFinder software, GAPDH/B2M, GAPDH/18S and UBCE/GAPDH were identified as the most suitable genes from samples taken of different developmental stages while 18S/RPL17 were consistently ranked as the best reference genes for different tissue types. Furthermore, TUBA/B2M, TUBA/UBCE and B2M/TUBA were found to be the most suitable genes in samples treated with the drug, SB-431542 by geNorm, BestKeeper and NormFinder respectively. Across both different developmental stages and tissue types, the combination of 18S and GAPDH was the most stable reference gene analyzed by Ref-Finder. To test and verify the screened reference genes, the expression profiles of LEFTY-normalized to the combination of GAPDH/18S and ACTB were presented. These results will be useful for future gene-expression studies in the half-smooth tongue sole. PMID:24667563

  20. Exposure assessment in auto collision repair shops.

    PubMed

    Bejan, Anca; Brosseau, Lisa M; Parker, David L

    2011-07-01

    Workers in auto collision shops are exposed to a variety of chemical and physical hazards. Previous studies have focused on measuring levels of isocyanates, but little is known about exposures to dust, noise, and solvents. In preparation for an intervention effectiveness study in small collision repair businesses, sampling was conducted on 3 consecutive days in four representative businesses with three to seven employees. Full-shift and task-specific exposures were measured for dust and solvents (for operations other than painting and spray gun cleaning). Full-shift personal exposures and tool-specific noise levels were also evaluated. Samples of banded earplugs were distributed to employees and feedback was collected after 1 week of wear time. Dust and solvent exposures did not exceed the OSHA PELs. Noise exposure doses were below the OSHA PEL; however, 4 of the 18 measurements were in excess of the ACGIH® threshold limit value. The majority of tools generated noise levels above 85 dBA. Air guns, wrenches, cutoff wheels, and air drills generated noise levels with the 5th percentile above 90 dBA. Mean noise levels generated by hammers, grinders, and ratchets were also above 95 dBA. Three pairs of banded earplugs had the best reviews in terms of comfort of use. This study was conducted during a time when all shops reported relatively low production levels. Noise exposure results suggest that it is likely that technicians' 8-hr time-weighted average exposures may be in excess of 85 dBA during periods of higher production, but exposures to dust and solvents are unlikely to approach OSHA exposure limits. These pilot test results will be useful when developing recommendations and technical assistance materials for health and safety interventions in auto collision repair businesses. PMID:21660833

  1. EXPOSURE MODELING - SHEDS

    EPA Science Inventory

    This presentation provides a general overview of SHEDS model features, describes algorithms in the SHEDS-Air Toxics model that focus on mobile source exposures and multipathway exposures, and presents examples of results from application of the SHEDS-Air Toxics model to benzene i...

  2. Dermal exposure assessment techniques.

    PubMed

    Fenske, R A

    1993-12-01

    Exposure of the skin to chemical substances can contribute significantly to total dose in many workplace situations, and its relative importance will increase when airborne occupational exposure limits are reduced, unless steps to reduce skin exposure are undertaken simultaneously. Its assessment employs personal sampling techniques to measure skin loading rates, and combines these measurements with models of percutaneous absorption to estimate absorbed dose. Knowledge of dermal exposure pathways is in many cases fundamental to hazard evaluation and control. When the skin is the primary contributor to absorbed dose, dermal exposure measurements and biological monitoring play complementary roles in defining occupational exposures. Exposure normally occurs by one of three pathways: (i) immersion (direct contact with a liquid or solid chemical substance); (ii) deposition of aerosol or uptake of vapour through the skin; or (iii) surface contact (residue transfer from contaminated surfaces). Sampling methods fall into three categories: surrogate skin; chemical removal; and fluorescent tracers. Surface sampling represents a supplementary approach, providing an estimate of dermal exposure potential. Surrogate skin techniques involve placing a chemical collection medium on the skin. Whole-body garment samplers do not require assumptions relating to distribution, an inherent limitation of patch sampling. The validity of these techniques rests on the ability of the sampling medium to capture and retain chemicals in a manner similar to skin. Removal techniques include skin washing and wiping, but these measure only what can be removed from the skin, not exposure: laboratory removal efficiency studies are required for proper interpretation of data. Fluorescent tracer techniques exploit the visual properties of fluorescent compounds, and combined with video imaging make quantification of dermal exposure patterns possible, but the need to introduce a chemical substance (tracer) into production processes represents an important limitation of this approach. Surface sampling techniques provide a measure of workplace chemical contamination. Wipe sampling has been used extensively, but is susceptible to high variability. Surface sampling requires definition of dermal transfer coefficients for specific work activities. A preliminary dermal exposure sampling strategy which addresses such issues as sampling method, representativeness and sample duration is proposed. Despite the limitations of current assessment techniques, it appears feasible to consider developing dermal occupational exposure limits (DOELs) for selected workplaces and chemical agents. Initial development of DOELs would be most practical where dermal exposure is from surface contact primarily, and where the work closely follows a routine. Improvement in the techniques of dermal exposure assessment is an important goal for occupational hygiene research, and is likely to lead to better health for worker populations. PMID:8304685

  3. Occupational Noise Exposure in the Printing Industry

    Microsoft Academic Search

    KEVIN J. McMAHON; PATRICK E. McMANUS

    1988-01-01

    The noise exposures of 274 printing production workers in 34 establishments in the New York city area were monitored. Results showed that 43% were exposed to 8-hr time-weighted average (TWA) noise exposures of 85 dBA or greater and that 14% were exposed to 8-hr TWAs of 90 dBA or greater. Within the press department, web press workers were exposed to

  4. Hairy cell leukaemia and occupational exposure to benzene.

    PubMed Central

    Clavel, J; Conso, F; Limasset, J C; Mandereau, L; Roche, P; Flandrin, G; Hémon, D

    1996-01-01

    OBJECTIVES: The role of occupational exposures in hairy cell leukaemia (HCL) was investigated through a multicentre, hospital based, case-control study. This paper analyses the role of exposure to benzene in HCL. METHODS: A population of 226 male cases of HCL and 425 matched controls were included in the study. Benzene exposure was evaluated by expert review of the detailed data on occupational exposures generated by case-control interviews. RESULTS: No association was found between HCL and employment in a job exposed to benzene (odds ratio (OR) 0.9 (95% confidence interval (95% CI) 0.6-1.3)). The sample included 125 subjects, 34 cases (15%), and 91 controls (21%) who had been exposed to benzene, as individually assessed by the experts, for at least one hour a month during one of their jobs. Benzene exposure was not associated with a risk of HCL (OR 0.8 (0.5-1.2)). No trend towards an increase in OR was detected for increasing exposures, the percentage of work time involving exposure to > 1 ppm, or the duration of exposure. No findings suggested a particular risk period, when the OR associated with the time since first or last exposure, or since the end of exposure, were examined. CONCLUSIONS: In conclusion, with the low exposures prevalent in the sample, the study did not show any association between benzene exposure and HCL. PMID:8983464

  5. Personal exposure of children to air pollution

    NASA Astrophysics Data System (ADS)

    Ashmore, M. R.; Dimitroulopoulou, C.

    Changes over recent decades in outdoor concentrations of air pollutants are well documented. However, the impacts of air pollution on an individual's health actually relate not to these outdoor concentrations but to their personal exposure in the different locations in which they spend time. Assessing how personal exposures differ from outdoor concentrations, and how they have changed over recent decades, is challenging. This review focuses on the exposure of children, since they are a particularly sensitive group. Much of children's time is spent indoors, and childhood exposure is closely related to concentrations in the home, at school, and in transport. For this reason, children's personal exposures to air pollutants differ significantly from both those of adults and from outdoor concentrations. They depend on a range of factors, including urbanisation, energy use, building design, travel patterns, and activity profiles; analysis of these factors can identify a wider range of policy measures to reduce children's exposure than direct emission control. There is a very large variation in personal exposure between individual children, caused by differences in building design, indoor and outdoor sources, and activity patterns. Identifying groups of children with high personal exposure, and their underlying causes, is particularly important in regions of the world where emissions are increasing, but there are limited resources for environmental and health protection. Although the science of personal exposure assessment, with the associated measurement and modelling techniques, has developed to maturity in North America and western Europe over the last 50 years, there is an urgent need to apply this science in other parts of the world where the effects of air pollution are now much more serious.

  6. Historical Estimation of Exposure to 1,3Butadiene, Styrene, and Dimethyldithiocarbamate Among Synthetic Rubber Workers

    Microsoft Academic Search

    Maurizio Macaluso; Rodney Larson; Jeremiah Lynch; Sydney Lipton; Elizabeth Delzell

    2004-01-01

    Quantitative estimates of exposure to 1,3-butadiene (BD), styrene (STY), and dimethyldithiocarbamate (DMDTC) were developed for a follow-up study of workers at six North American synthetic rubber plants. Procedures entailed identifying tasks and jobs involving exposure, identifying factors influencing historical changes in exposure potential, and using mathematical models to calculate job- and time-period-specific exposures. Exposure metrics included 8-hour time-weighted average (TWA)

  7. Nuclear Energy: Radiation Exposure

    NSDL National Science Digital Library

    John Pratte

    This lesson provides an overview of the sources and potential effects of radiation exposure. Topics include the history of the United States' domestic nuclear power program, the concept of ionizing radiation, and how radiation dosage is measured. There is also discussion of what constitutes a lethal dose of radiation and potential sources of exposure. The lesson includes an activity in which students measure their individual yearly exposures to radiation by making an inventory of lifestyle factors that affect their potential dosage and using an online calculator to sum up the contributions from the various sources.

  8. Cluster-based exposure variation analysis

    PubMed Central

    2013-01-01

    Background Static posture, repetitive movements and lack of physical variation are known risk factors for work-related musculoskeletal disorders, and thus needs to be properly assessed in occupational studies. The aims of this study were (i) to investigate the effectiveness of a conventional exposure variation analysis (EVA) in discriminating exposure time lines and (ii) to compare it with a new cluster-based method for analysis of exposure variation. Methods For this purpose, we simulated a repeated cyclic exposure varying within each cycle between “low” and “high” exposure levels in a “near” or “far” range, and with “low” or “high” velocities (exposure change rates). The duration of each cycle was also manipulated by selecting a “small” or “large” standard deviation of the cycle time. Theses parameters reflected three dimensions of exposure variation, i.e. range, frequency and temporal similarity. Each simulation trace included two realizations of 100 concatenated cycles with either low (??=?0.1), medium (??=?0.5) or high (??=?0.9) correlation between the realizations. These traces were analyzed by conventional EVA, and a novel cluster-based EVA (C-EVA). Principal component analysis (PCA) was applied on the marginal distributions of 1) the EVA of each of the realizations (univariate approach), 2) a combination of the EVA of both realizations (multivariate approach) and 3) C-EVA. The least number of principal components describing more than 90% of variability in each case was selected and the projection of marginal distributions along the selected principal component was calculated. A linear classifier was then applied to these projections to discriminate between the simulated exposure patterns, and the accuracy of classified realizations was determined. Results C-EVA classified exposures more correctly than univariate and multivariate EVA approaches; classification accuracy was 49%, 47% and 52% for EVA (univariate and multivariate), and C-EVA, respectively (p?exposure patterns differing with respect to the variability in cycle time duration. Conclusion While C-EVA had a higher accuracy than conventional EVA, both failed to detect differences in temporal similarity. The data-driven optimality of data reduction and the capability of handling multiple exposure time lines in a single analysis are the advantages of the C-EVA. PMID:23557439

  9. Combat exposure and mental health: the long?term effects among US Vietnam and Gulf war veterans

    Microsoft Academic Search

    Daniel M. Gade; Jeffrey B. Wenger

    2011-01-01

    Using a random sample of more than 4000 veterans, we test the effects of combat exposure on mental health. We focus on two cohorts of veterans: those who served in Vietnam (1964–1975) and the Gulf War (1990–1991). Combat exposure differed between these groups in intensity, duration and elapsed time since exposure. We find that combat exposure generally, and exposure to

  10. Changes in Television and Magazine Exposure and Eating Disorder Symptomatology

    Microsoft Academic Search

    Kimberley K. Vaughan; Gregory T. Fouts

    2003-01-01

    The relationship between girls' media exposure and their development of eating disorder symptomatology was assessed. At Time 1 and Time 2 (16 months later), participants (N = 374; M age = 12.0) completed a questionnaire that assessed eating disorder sympto-matology and television and fashion magazine exposure. Girls were divided into 3 groups: increased, decreased, or no change in eating disorder

  11. Pesticide-Exposure Matrix

    Cancer.gov

    The "Pesticide-exposure Matrix" was developed to help epidemiologists and other researchers identify the active ingredients to which people were likely exposed when their homes and gardens were treated for pests in past years.

  12. Nanotechnology and Exposure Science

    PubMed Central

    LIOY, PAUL J.; NAZARENKO, YEVGEN; HAN, TAE WON; LIOY, MARY JEAN; MAINELIS, GEDIMINAS

    2014-01-01

    This article discusses the gaps in our understanding of human exposures to nanoparticles stemming from the use of nanotechnology-based consumer products by the general public. It also describes a series of steps that could be taken to characterize such exposures. The suggested steps include classification of the nanotechnology-based products, simulation of realistic exposure patterns, characterization of emissions, analysis of the duration of activities resulting in exposures, and consideration of the bioaccessibility of nanoparticles. In addition, we present a preliminary study with nanotechnology-based cosmetic powders where particle release was studied under realistic powder application conditions. The data demonstrated that when nanotechnology-based cosmetic powders were used, there was a potential for inhaling airborne particles ranging in size from tens of nanometers to tens of micrometers. PMID:21222382

  13. Pesticide exposure in children.

    PubMed

    2012-12-01

    This statement presents the position of the American Academy of Pediatrics on pesticides. Pesticides are a collective term for chemicals intended to kill unwanted insects, plants, molds, and rodents. Children encounter pesticides daily and have unique susceptibilities to their potential toxicity. Acute poisoning risks are clear, and understanding of chronic health implications from both acute and chronic exposure are emerging. Epidemiologic evidence demonstrates associations between early life exposure to pesticides and pediatric cancers, decreased cognitive function, and behavioral problems. Related animal toxicology studies provide supportive biological plausibility for these findings. Recognizing and reducing problematic exposures will require attention to current inadequacies in medical training, public health tracking, and regulatory action on pesticides. Ongoing research describing toxicologic vulnerabilities and exposure factors across the life span are needed to inform regulatory needs and appropriate interventions. Policies that promote integrated pest management, comprehensive pesticide labeling, and marketing practices that incorporate child health considerations will enhance safe use. PMID:23184103

  14. NATIONAL EXPOSURE REGISTRY (NER)

    EPA Science Inventory

    This system is a listing of persons (general population) with documented exposure to select hazardous substances (superfund related). All adverse health outcomes are monitored prospectively. Retrospective identification of adverse health outcomes (usually verified by medical reco...

  15. Pregnancy and Radiation Exposure

    MedlinePLUS

    ... Exposure to the Embryo or Fetus from Diagnostic Nuclear Medicine Pregnant women may be administered radioactive materials ... determination be obtained from the health physicist, a nuclear medicine physician, or a radiation oncologist associated with ...

  16. Effects of Pulsed Contaminant Exposures on Early Life Stages of the Fathead Minnow

    Microsoft Academic Search

    Jerome Diamond; Marcus Bowersox; Henry Latimer; Chad Barbour; Jonathan Bearr; Jonathan Butcher

    2005-01-01

    Water quality standards for protecting aquatic life are based primarily on laboratory tests that use constant exposure concentrations. Typical effluent and nonpoint source exposure concentrations fluctuate in frequency, magnitude, and duration, which may result in different toxicological impacts. Current information indicates that pulsed or fluctuating exposures are generally more toxic than continuous exposures, when averaged over the applicable time period.

  17. Autoimmunity and Asbestos Exposure

    PubMed Central

    Pfau, Jean C.; Serve, Kinta M.; Noonan, Curtis W.

    2014-01-01

    Despite a body of evidence supporting an association between asbestos exposure and autoantibodies indicative of systemic autoimmunity, such as antinuclear antibodies (ANA), a strong epidemiological link has never been made to specific autoimmune diseases. This is in contrast with another silicate dust, crystalline silica, for which there is considerable evidence linking exposure to diseases such as systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Instead, the asbestos literature is heavily focused on cancer, including mesothelioma and pulmonary carcinoma. Possible contributing factors to the absence of a stronger epidemiological association between asbestos and autoimmune disease include (a) a lack of statistical power due to relatively small or diffuse exposure cohorts, (b) exposure misclassification, (c) latency of clinical disease, (d) mild or subclinical entities that remain undetected or masked by other pathologies, or (e) effects that are specific to certain fiber types, so that analyses on mixed exposures do not reach statistical significance. This review summarizes epidemiological, animal model, and in vitro data related to asbestos exposures and autoimmunity. These combined data help build toward a better understanding of the fiber-associated factors contributing to immune dysfunction that may raise the risk of autoimmunity and the possible contribution to asbestos-related pulmonary disease. PMID:24876951

  18. The contributions to solvent uptake by skin and inhalation exposure

    SciTech Connect

    Daniell, W.; Stebbins, A.; Kalman, D.; O'Donnell, J.F.; Horstman, S.W. (Department of Environmental Health, University of Washington, Seattle (United States))

    1992-02-01

    Solvent exposures were assessed among 97 auto body repair workers in order to determine whether skin contact represented a significant route of exposure. Each subject's cumulative skin exposure was ranked categorically based on simple observation: 49 none, 33 incidental or low, and 15 moderate or high. The median time-weighted average air exposure to solvents was 8.4% of the American Conference of Governmental Industrial Hygienists (ACGIH) combined solvent threshold limit value (TLV) with a range of 0-62% TLV, including toluene (median 4 ppm) and xylenes (median 0.9 ppm). Urine methyl hippuric acids (MHAs, metabolites of xylenes) were low compared to the ACGIH biological exposure index (BEI) with a median of 2% and a range of 0-12% BEI but were strongly correlated with both the level of airborne xylenes and skin exposure when considered simultaneously by using analysis of covariance (R = 0.91, p less than 0.0001). MHA excretion attributable to skin exposure for 15 min or more generally was comparable to or greater than that from associated air exposure over the full work shift. This study had limited ability to assess quantitatively the contributions of toluene exposures, but there was evidence that skin exposures also contributed significantly to toluene absorption. Air sampling will substantially underestimate a worker's total solvent dose in the setting of moderate or high skin exposure. Simple observation was effective in identifying workers in this sample who appeared to have sufficient skin exposure to produce a measurable increase in solvent uptake.

  19. Pesticide exposure in children.

    PubMed

    Roberts, James R; Karr, Catherine J

    2012-12-01

    Pesticides are a collective term for a wide array of chemicals intended to kill unwanted insects, plants, molds, and rodents. Food, water, and treatment in the home, yard, and school are all potential sources of children's exposure. Exposures to pesticides may be overt or subacute, and effects range from acute to chronic toxicity. In 2008, pesticides were the ninth most common substance reported to poison control centers, and approximately 45% of all reports of pesticide poisoning were for children. Organophosphate and carbamate poisoning are perhaps the most widely known acute poisoning syndromes, can be diagnosed by depressed red blood cell cholinesterase levels, and have available antidotal therapy. However, numerous other pesticides that may cause acute toxicity, such as pyrethroid and neonicotinoid insecticides, herbicides, fungicides, and rodenticides, also have specific toxic effects; recognition of these effects may help identify acute exposures. Evidence is increasingly emerging about chronic health implications from both acute and chronic exposure. A growing body of epidemiological evidence demonstrates associations between parental use of pesticides, particularly insecticides, with acute lymphocytic leukemia and brain tumors. Prenatal, household, and occupational exposures (maternal and paternal) appear to be the largest risks. Prospective cohort studies link early-life exposure to organophosphates and organochlorine pesticides (primarily DDT) with adverse effects on neurodevelopment and behavior. Among the findings associated with increased pesticide levels are poorer mental development by using the Bayley index and increased scores on measures assessing pervasive developmental disorder, inattention, and attention-deficit/hyperactivity disorder. Related animal toxicology studies provide supportive biological plausibility for these findings. Additional data suggest that there may also be an association between parental pesticide use and adverse birth outcomes including physical birth defects, low birth weight, and fetal death, although the data are less robust than for cancer and neurodevelopmental effects. Children's exposures to pesticides should be limited as much as possible. PMID:23184105

  20. Asbestos exposure in buildings

    SciTech Connect

    Gaensler, E.A. (Department of Surgery, Boston University School of Medicine, MA (United States))

    1992-06-01

    Asbestos-related diseases are dose-related. Among these, asbestosis has occurred only with the heavy exposures of the past, is a disappearing disease, and is of no concern with the very small exposures from building occupancy. A possibly increased incidence of lung cancer has been included in risk analysis, but probably is also related to high exposure in that both epidemiologic and experimental data suggest a link between the process of alveolar inflammation and fibrogenesis and carcinogenesis. The major concern has been mesothelioma in that it has occurred with much lower household and neighborhood exposure. Additionally, anxiety concerning buildings with ACM has been heightened by finding of friable asbestos in about 20% of public buildings, discovery of environmental asbestos fibers and asbestos bodies in autopsies, and demonstration of a linear relationship between exposure and lung cancer risk in occupational groups, inviting extrapolation to a much lower dose. Legislative and regulatory mandates, promotional activities of abatement companies, adverse court decisions placing the onus of repairs on asbestos manufacturers, and a pandemic of mediagenic disease' all have contributed to panic among building owners, school boards, insurers, and others. In that there is neither clinical nor epidemiologic support for asbestos-related disease from building occupancy, risk estimates have been based on extrapolation from past experience with generally high-dose occupational exposure. However, only a few epidemiologic studies have contained quantitative estimates of exposure, and these have been measured in terms of all particles, with conversion to asbestos fibers uncertain and the fiber type and dimension largely unknown.

  1. Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

    PubMed Central

    Kazmi, S. M. Shams; Balial, Satyajit; Dunn, Andrew K.

    2014-01-01

    Improved Laser Speckle Contrast Imaging (LSCI) blood flow analyses that incorporate inverse models of the underlying laser-tissue interaction have been used to develop more quantitative implementations of speckle flowmetry such as Multi-Exposure Speckle Imaging (MESI). In this paper, we determine the optimal camera exposure durations required for obtaining flow information with comparable accuracy with the prevailing MESI implementation utilized in recent in vivo rodent studies. A looping leave-one-out (LOO) algorithm was used to identify exposure subsets which were analyzed for accuracy against flows obtained from analysis with the original full exposure set over 9 animals comprising n = 314 regional flow measurements. From the 15 original exposures, 6 exposures were found using the LOO process to provide comparable accuracy, defined as being no more than 10% deviant, with the original flow measurements. The optimal subset of exposures provides a basis set of camera durations for speckle flowmetry studies of the microcirculation and confers a two-fold faster acquisition rate and a 28% reduction in processing time without sacrificing accuracy. Additionally, the optimization process can be used to identify further reductions in the exposure subsets for tailoring imaging over less expansive flow distributions to enable even faster imaging. PMID:25071956

  2. Asbestos Exposure Assessment Database

    NASA Technical Reports Server (NTRS)

    Arcot, Divya K.

    2010-01-01

    Exposure to particular hazardous materials in a work environment is dangerous to the employees who work directly with or around the materials as well as those who come in contact with them indirectly. In order to maintain a national standard for safe working environments and protect worker health, the Occupational Safety and Health Administration (OSHA) has set forth numerous precautionary regulations. NASA has been proactive in adhering to these regulations by implementing standards which are often stricter than regulation limits and administering frequent health risk assessments. The primary objective of this project is to create the infrastructure for an Asbestos Exposure Assessment Database specific to NASA Johnson Space Center (JSC) which will compile all of the exposure assessment data into a well-organized, navigable format. The data includes Sample Types, Samples Durations, Crafts of those from whom samples were collected, Job Performance Requirements (JPR) numbers, Phased Contrast Microscopy (PCM) and Transmission Electron Microscopy (TEM) results and qualifiers, Personal Protective Equipment (PPE), and names of industrial hygienists who performed the monitoring. This database will allow NASA to provide OSHA with specific information demonstrating that JSC s work procedures are protective enough to minimize the risk of future disease from the exposures. The data has been collected by the NASA contractors Computer Sciences Corporation (CSC) and Wyle Laboratories. The personal exposure samples were collected from devices worn by laborers working at JSC and by building occupants located in asbestos-containing buildings.

  3. Micronuclei and pesticide exposure.

    PubMed

    Bolognesi, Claudia; Creus, Amadeu; Ostrosky-Wegman, Patricia; Marcos, Ricard

    2011-01-01

    Micronucleus (MN) is a biomarker widely used in biomonitoring studies carried out to determine the genetic risk associated to pesticide exposure. Many in vitro and in vivo studies, as well as epidemiological approaches, have demonstrated the ability of certain chemical pesticides to produce genetic effects including cancer and other chronic pathologies in humans; thus, biomonitoring studies have been carried out to characterise the genetic risk associated to pesticide exposure. It must be noted that 'pesticide exposure' is a broad term covering complex mixtures of chemicals and many variables that can reduce or potentiate their risk. In addition, there are large differences in pesticides used in the different parts of the world. Although pesticides constitute a wide group of environmental pollutants, the main focus on their risk has been addressed to people using pesticides in their working places, at the chemical industry or in the crop fields. Here, we present a brief review of biomonitoring studies carried out in people occupationally exposed to pesticides and that use MN in lymphocytes or buccal cells as a target to determine the induction of genotoxic damage. Thus, people working in the chemical industry producing pesticides, people spraying pesticides and people dedicated to floriculture or agricultural works in general are the subject of specific sections. MN is a valuable genotoxic end point when clear exposure conditions exist like in pesticide production workers; nevertheless, better study designs are needed to overcome the uncertainty in exposure, genetic susceptibility and statistical power in the studies of sprayers and floriculture or agricultural workers. PMID:21164178

  4. Chronic Ambient Hydrogen Sulfide Exposure and Cognitive Function

    PubMed Central

    Reed, Bruce R.; Crane, Julian; Garrett, Nick; Woods, David L.; Bates, Michael N.

    2014-01-01

    Background Exposures to hydrogen sulfide gas (H2S) have been inconclusively linked to a variety of negative cognitive outcomes. We investigated possible effects on cognitive function in an urban population with chronic, low-level exposure to H2S. Methods Participants were 1,637 adults, aged 18-65 years from Rotorua city, New Zealand, exposed to ambient H2S from geothermal sources. Exposures at homes and workplaces were estimated from data collected by summer and winter H2S monitoring networks across Rotorua in 2010/11. Metrics for H2S exposure at the time of participation and for exposure over the last 30 years were calculated. H2S exposure was modeled both as continuous variables and as quartiles of exposure covering the range of 0 – 64 ppb (0-88 ?g/m3). Outcomes were neuropsychological tests measuring visual and verbal episodic memory, attention, fine motor skills, psychomotor speed and mood. Associations between cognition and measures of H2S exposure were investigated with multiple regression, while covarying demographics and factors known to be associated with cognitive performance. Results The consistent finding was of no association between H2S exposure and cognition. Quartiles of H2S exposure had a small association with simple reaction time: higher exposures were associated with faster response times. Similarly, for digit symbol, higher H2S exposures tended to be marginally associated with better performance. Conclusion The results provide evidence that chronic H2S exposure, at the ambient levels found in and around Rotorua, is not associated with impairment of cognitive function. PMID:24548790

  5. Inhalation exposure methodology.

    PubMed Central

    Phalen, R F; Mannix, R C; Drew, R T

    1984-01-01

    Modern man is being confronted with an ever-increasing inventory of potentially toxic airborne substances. Exposures to these atmospheric contaminants occur in residential and commercial settings, as well as in the workplace. In order to study the toxicity of such materials, a special technology relating to inhalation exposure systems has evolved. The purpose of this paper is to provide a description of the techniques which are used in exposing laboratory subjects to airborne particles and gases. The various modes of inhalation exposure (whole body, head only, nose or mouth only, etc.) are described at length, including the advantages and disadvantages inherent to each mode. Numerous literature citations are included for further reading. Among the topics briefly discussed are the selection of appropriate animal species for toxicological testing, and the types of inhalation studies performed (acute, chronic, etc.). PMID:6383799

  6. Toxic inhalational exposures.

    PubMed

    Chen, Tze-Ming Benson; Malli, Harjoth; Maslove, David M; Wang, Helena; Kuschner, Ware G

    2013-01-01

    Respirable toxicants are a spectrum of irritant and nonirritant gases, vapors, fumes, and airborne particles that can be entrained into the body through the respiratory tract, resulting in exposures that cause pulmonary injury and/or systemic disease. Sources of respirable toxicants include structural fires, industrial accidents, domestic mishaps, and intentional releases of injurious agents on the battleground (warfare) or in civilian settings (acts of terrorism). Acute toxic inhalational exposures may result in respiratory failure, multisystem organ dysfunction, and death. Management of victims includes assessment and protection of the airway, monitoring and treatment of systemic toxicity, and delivery of exposure-specific and nonspecific therapies that improve outcomes. Treatments may include antidotes, hyperbaric oxygen, and other nonspecific life-supporting interventions. PMID:22232204

  7. Americans' Average Radiation Exposure

    SciTech Connect

    NA

    2000-08-11

    We live with radiation every day. We receive radiation exposures from cosmic rays, from outer space, from radon gas, and from other naturally radioactive elements in the earth. This is called natural background radiation. It includes the radiation we get from plants, animals, and from our own bodies. We also are exposed to man-made sources of radiation, including medical and dental treatments, television sets and emission from coal-fired power plants. Generally, radiation exposures from man-made sources are only a fraction of those received from natural sources. One exception is high exposures used by doctors to treat cancer patients. Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body.

  8. Exposure to atmospheric radon.

    PubMed Central

    Steck, D J; Field, R W; Lynch, C F

    1999-01-01

    We measured radon (222Rn) concentrations in Iowa and Minnesota and found that unusually high annual average radon concentrations occur outdoors in portions of central North America. In some areas, outdoor concentrations exceed the national average indoor radon concentration. The general spatial patterns of outdoor radon and indoor radon are similar to the spatial distribution of radon progeny in the soil. Outdoor radon exposure in this region can be a substantial fraction of an individual's total radon exposure and is highly variable across the population. Estimated lifetime effective dose equivalents for the women participants in a radon-related lung cancer study varied by a factor of two at the median dose, 8 mSv, and ranged up to 60 mSv (6 rem). Failure to include these doses can reduce the statistical power of epidemiologic studies that examine the lung cancer risk associated with residential radon exposure. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:9924007

  9. Ultra-accelerated natural sunlight exposure testing

    DOEpatents

    Jorgensen, Gary J. (Pine, CO); Bingham, Carl (Lakewood, CO); Goggin, Rita (Englewood, CO); Lewandowski, Allan A. (Evergreen, CO); Netter, Judy C. (Westminster, CO)

    2000-06-13

    Process and apparatus for providing ultra accelerated natural sunlight exposure testing of samples under controlled weathering without introducing unrealistic failure mechanisms in exposed materials and without breaking reciprocity relationships between flux exposure levels and cumulative dose that includes multiple concurrent levels of temperature and relative humidity at high levels of natural sunlight comprising: a) concentrating solar flux uniformly; b) directing the controlled uniform sunlight onto sample materials in a chamber enclosing multiple concurrent levels of temperature and relative humidity to allow the sample materials to be subjected to accelerated irradiance exposure factors for a sufficient period of time in days to provide a corresponding time of about at least a years worth of representative weathering of the sample materials.

  10. Perchloroethylene exposure assessment among dry cleaning workers

    SciTech Connect

    Solet, D.; Robins, T.G.; Sampaio, C. (Univ. of Michigan, Ann Arbor (USA))

    1990-10-01

    Perchloroethylene (Perc), the most widely used solvent in dry cleaning, is toxic to the liver, kidneys, and central nervous system and may be a human carcinogen. In the Detroit area, as part of a project investigating the health status of dry cleaning workers, an exposure assessment was carried out in dry cleaning plants using perchloroethylene. Breath samples were obtained from each participant, and time-weighted average (TWA) breathing zone air samples were obtained using passive dosimeters on a subset expected to experience a range of exposures. Perc in breath and Perc in air were highly correlated (r2 = 0.75, p less than 0.0001). On average, operators of dry cleaning equipment experienced significantly more exposure than nonoperators. Also, employees working in shops that use transfer equipment (requiring physical transfer of Perc-saturated clothing from washers to dryers) showed significantly higher exposure than those in shops utilizing dry-to-dry machinery (permitting washing and drying in one machine in a single cycle). One or more air samples in every transfer shop exceeded the recently revised Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 25 ppm, while no air samples in dry-to-dry shops exceeded this limit. The results suggest concern for exposures to operators in transfer shops and that compliance with the PEL is achievable by engineering controls with presently existing technology.

  11. Cytogenetic research after accidental radiation exposure.

    PubMed

    Bauchinger, M

    1995-05-01

    Currently, chromosome aberration analysis in peripheral lymphocytes is the most sensitive method to estimate individual doses in accidental radiation exposures. The assessment of dose is particularly reliable in cases with acute, uniform, whole-body exposure or after irradiation of large parts of the body. However, the scenarios of most radiation accidents largely result in partial-body exposures or a non-uniform dose distribution. This complicates dose estimation especially in cases with protracted or fractionated exposures. Problems exist also for the dose reconstruction of radiation exposures occurring a long time before sampling. To overcome these problems, the Qdr method or the "contaminated Poisson" method can be used to determine meaningful dose estimates from data based on conventional scoring of dicentrics. Scoring of so-called stable translocations by the newly developed technique of chromosome painting should be particularly useful for estimating doses of past exposures or of dose accumulation. After incorporation of radionuclides with largely localized depositions in certain organs or tissues, realistic individual dose estimates cannot be achieved. Exemplified by incidents involving larger groups of the population such as in Chernobyl and Goiania and by single cases with serious overexposures, chromosome dosimetry is evaluated in the present article. PMID:7488944

  12. Acidic sulfate aerosols: characterization and exposure.

    PubMed Central

    Lioy, P J; Waldman, J M

    1989-01-01

    Exposures to acidic aerosol in the atmosphere are calculated from data reported in the scientific literature. The majority of date was not derived from studies necessarily designed to examine human exposures. Most of the studies were designed to investigate the characteristics of the atmosphere. However, the measurements were useful in defining two potential exposure situations: regional stagnation and transport conditions and local plume impacts. Levels of acidic aerosol in excess of 20 to 40 micrograms/m3 (as H2SO4) have been observed for time durations ranging from 1 to 12 hr. These were associated with high, but not necessarily the highest, atmospheric SO4(2)- levels. Exposures of 100 to 900 micrograms/m3/hr were calculated for the acid events that were monitored. In contrast, earlier London studies indicated that apparent acidity in excess of 100 micrograms/m3 (as H2SO4) was present in the atmosphere, and exposures less than 2000 micrograms/m3/hr were possible. Our present knowledge about the frequency, magnitude, and duration of acidic sulfate aerosol events and episodes is insufficient. Efforts must be made to gather more data, but these should be done in such a way that evaluation of human exposure is the focus of the research. In addition, further data are required on the mechanisms of formation of H2SO4 and on what factors can be used to predict acidic sulfate episodes. PMID:2651103

  13. Exposure to o-toluidine, aniline, and nitrobenzene in a rubber chemical manufacturing plant: a retrospective exposure assessment update.

    PubMed

    Hanley, Kevin W; Viet, Susan M; Hein, Misty J; Carreón, Tania; Ruder, Avima M

    2012-01-01

    The National Institute for Occupational Safety and Health previously conducted a retrospective cancer incidence and mortality study of workers employed at a rubber chemical manufacturing plant. Compared with New York State incidence, the bladder cancer risk was 6.5 times higher for workers considered to have definite exposure to ortho-toluidine and aniline, and 4 times higher for workers with possible exposure. Exposure characterization in the original study utilized a surrogate measure based only on departments in which each worker was ever employed. As part of an update of that study, some departments in the three original exposure groups were reclassified based on a follow-up site visit; interviews with employees, management, and union representatives; and review of records including exposure data. An additional evaluation of department-job combinations, rather than only departments, was used to stratify exposure into four categories. An approximate rank of "relative" exposure level for each department-job-year combination was also assigned using a ranking scale of 0 to 10. The ranks were supported by quantitative exposure levels and by professional judgment. The numerical ranking scale was applied to each worker by multiplying the exposure rank by duration for each job held based on comprehensive individual work histories. The cumulative rank scores for this cohort ranged from 0 to 300 unit-years. The medians of the cumulative rank scores for the exposure categories showed very good agreement with increasing exposure classifications (e.g., 0.72, 4.6, 11, 14 unit-years for the four exposure categories). Workers' breathing zone air sampling data collected at this plant from 1976-2004 were well below published occupational exposure limits for these chemicals, but additional cases of bladder cancer have been reported. The exposure assessment revisions and rank estimates will be used to analyze the updated bladder cancer incidence data. PMID:22708702

  14. Proteomic Analyses of Corneal Tissue Subjected to Alkali Exposure

    PubMed Central

    Parikh, Toral; Eisner, Natalie; Venugopalan, Praseeda; Yang, Qin; Lam, Byron L.

    2011-01-01

    Purpose. To determine whether exposure to alkaline chemicals results in predictable changes in corneal protein profile. To determine whether protein profile changes are indicative of severity and duration of alkali exposure. Methods. Enucleated bovine and porcine (n = 59 each) eyes were used for exposure to sodium, ammonium, and calcium hydroxide, respectively. Eyes were subjected to fluorescein staining, 5-bromo-2?-deoxy-uridine (BrdU) labeling. Excised cornea was subjected to protein extraction, spectrophotometric determination of protein amount, dynamic light scattering and SDS-PAGE profiling, mass spectrometric protein identification, and iTRAQ-labeled quantification. Select identified proteins were subjected to Western blot and immunohistochemical analyses. Results. Alkali exposure resulted in lower protein extractability from corneal tissue. Elevated aggregate formation was found with strong alkali exposure (sodium hydroxide>ammonium, calcium hydroxide), even with a short duration of exposure compared with controls. The protein yield after exposure varied as a function of postexposure time. Protein profiles changed because of alkali exposure. Concentration and strength of the alkali affected the profile change significantly. Mass spectrometry identified 15 proteins from different bands with relative quantification. Plexin D1 was identified for the first time in the cornea at a protein level that was further confirmed by Western blot and immunohistochemical analyses. Conclusions. Exposure to alkaline chemicals results in predictable and reproducible changes in corneal protein profile. Stronger alkali, longer durations, or both, of exposure resulted in lower yields and significant protein profile changes compared with controls. PMID:20861482

  15. Simplified evacuation model for estimating mitigation of early population exposures

    SciTech Connect

    Strenge, D.L.

    1980-12-01

    The application of a simple evacuation model to the prediction of expected population exposures following acute releases of activity to the atmosphere is described. The evacuation model of Houston is coupled with a normalized Gaussian dispersion calculation to estimate the time integral of population exposure. The methodology described can be applied to specific sites to determine the expected reduction of population exposures due to evacuation.

  16. Exposure Modeling of Benzene Exploiting Passive–Active Sampling Data

    Microsoft Academic Search

    Spyros P. Karakitsios; Pavlos A. Kassomenos; Dimosthenis A. Sarigiannis; Georgios A. Pilidis

    2010-01-01

    The objective of the present study is the exploitation of active sampling personal exposure data in assessing the factors\\u000a that affect exposure to benzene in combination with the widely accepted scheme of passive sampling—time microenvironment–activity\\u000a diaries (TMAD). The campaign included personal exposure measurements with both passive and active sampling in several microenvironments,\\u000a evaluation of TMAD kept by the volunteers, and

  17. [Algorithm for assessment of exposure to asbestos].

    PubMed

    Martines, V; Fioravanti, M; Anselmi, A; Attili, F; Battaglia, D; Cerratti, D; Ciarrocca, M; D'Amelio, R; De Lorenzo, G; Ferrante, E; Gaudioso, F; Mascia, E; Rauccio, A; Siena, S; Palitti, T; Tucci, L; Vacca, D; Vigliano, R; Zelano, V; Tomei, F; Sancini, A

    2010-01-01

    There is no universally approved method in the scientific literature to identify subjects exposed to asbestos and divide them in classes according to intensity of exposure. The aim of our work is to study and develope an algorithm based on the findings of occupational anamnestical information provided by a large group of workers. The algorithm allows to discriminate, in a probabilistic way, the risk of exposure by the attribution of a code for each worker (ELSA Code--work estimated exposure to asbestos). The ELSA code has been obtained through a synthesis of information that the international scientific literature identifies as the most predictive for the onset of asbestos-related abnormalities. Four dimensions are analyzed and described: 1) present and/or past occupation; 2) type of materials and equipment used in performing working activity; 3) environment where these activities are carried out; 4) period of time when activities are performed. Although it is possible to have informations in a subjective manner, the decisional procedure is objective and is based on the systematic evaluation of asbestos exposure. From the combination of the four identified dimensions it is possible to have 108 ELSA codes divided in three typological profiles of estimated risk of exposure. The application of the algorithm offers some advantages compared to other methods used for identifying individuals exposed to asbestos: 1) it can be computed both in case of present and past exposure to asbestos; 2) the classification of workers exposed to asbestos using ELSA code is more detailed than the one we have obtained with Job Exposure Matrix (JEM) because the ELSA Code takes in account other indicators of risk besides those considered in the JEM. This algorithm was developed for a project sponsored by the Italian Armed Forces and is also adaptable to other work conditions for in which it could be necessary to assess risk for asbestos exposure. PMID:20684436

  18. Effects of Developmental Lead Exposure on the Hippocampal Transcriptome: Influences of Sex, Developmental Period, and Lead Exposure Level

    PubMed Central

    Schneider, Jay S

    2012-01-01

    Developmental lead (Pb) exposure has profound effects on cognition and behavior. Much is known about effects of Pb on hippocampal-mediated behaviors, but little is known about the molecular consequences of Pb exposure and the influences of developmental timing of exposure, level of exposure, and sex as effect modifiers of Pb exposure on the brain. The aim of this study was to examine the effects of different levels of Pb exposure (250 and 750 ppm Pb acetate) during perinatal (gestation/lactation) and postnatal (through postnatal day 45) periods on the hippocampal transcriptome in male and female Long Evans rats. Total RNA was extracted from hippocampus from four animals per experimental condition. RNA was hybridized to Affymetrix Rat Gene RNA Arrays using standard methods. Pb exposure per se influenced the expression of 717 transcripts (328 unique annotated genes), with many influenced in a sex-independent manner. Significant differences in gene expression patterns were also influenced by timing and level of exposure, with generally larger effects at the lower level of exposure across all groups. Statistically enriched biological functions included ion binding, regulation of RNA metabolic processes, and positive regulation of macromolecule biosynthetic processes. Processes of regulation of transcription and regulation of gene expression were preferentially enriched in males, regardless of timing or amount of Pb exposure. The effect on transcription factors and the diverse pathways or networks affected by Pb suggest a substantial effect of developmental Pb exposure on plasticity and adaptability, with these effects significantly modified by sex, developmental window of exposure, and level of Pb exposure. PMID:22641619

  19. Aggregation of exposure level and probability into a single metric in job-exposure matrices creates bias.

    PubMed

    Burstyn, Igor; Lavoué, Jérôme; Van Tongeren, Martie

    2012-11-01

    Job-exposure matrices (JEMs) are often used in occupational epidemiological studies to provide an exposure estimate for a typical person in a 'job' during a particular time period. A JEM can produce exposure estimates on a variety of scales, such as (but not limited to) binary assessments of presence or absence of exposure, ordinal ranking of exposure level and frequency, and quantitative exposure estimates of exposure intensity and frequency. Specifically, one popular approach to construct a JEM, engendered in a Finnish job exposure matrix (FINJEM), provides a probability that a worker within an occupational group is exposed and an estimate of intensity of exposure among the exposed workers within this occupation. Often the product of the probability and intensity (aka level) is used to obtain the estimate of exposure for the epidemiological analyses. This procedure aggregates exposure across exposed and non-exposed individuals and the effect of this particular procedure on epidemiological analyses has never been studied. We developed a theoretical framework for understanding how these aggregate exposure estimates relate to true exposure (either unexposed or log-normally distributed for 'exposed'), assuming that there is no uncertainty about estimates of level and probability of exposure. Theoretical derivations show that multiplying occupation-specific exposure level and probability of non-zero exposure results in both systematic and differential measurement errors. Simulations demonstrated that under certain conditions bias in odds ratios in a cohort study away from the null are possible and that this bias is smaller when (a) arithmetic rather than geometric mean is used to assess exposure level and (b) exposure level and prevalence are positively correlated. We illustrate the potential impact of using the specified JEM in a simulation based on a case-control study of non-Hodgkin lymphoma and exposure to ionizing and non-ionizing radiation. Inflation of standard errors in the log-odds was observed as well as bias away from null for two out of three specific exposures/data structures. Overall, it is clear that influence of the phenomenon we studied on epidemiological results is complex and difficult to predict, being influenced a great deal by the structure of data. We recommend exploring the influence of JEMs that use the product of exposure level and probability in epidemiological analyses through simulations during planning of such studies to assess both the expected extent of the potential bias in risk estimates and impact on power. The SAS and R code required to implement such simulations are provided. All our calculations are either theoretical or based on simulated data. PMID:22986426

  20. Occupational noise exposure: how should we measure it

    SciTech Connect

    Barry, J.P.

    1982-01-01

    Historically, the American hygiene community has measured occupational noise exposure with a general purpose (ANSI type 2) sound level meter set to indicate A-weighted sound levels at slow response and a watch to indicate the exposure duration. Occupational noise exposures have been calculated by summing the fractions of the actual exposure time at a given A-weighted sound level over the permissible exposure time for that level. If the noise dose obtained by this method exceeded unity or 100%, then excessive exposure was documented for hearing conservation purposes. With the advent of the US Department of Labor's statutorily enforceable occupational noise standards in 1969 and 1971, the need arose for a less time-consuming way to do a workplace noise exposure survey. The answer was the personal noise dosimeter which automatically measures the A-weighted sound levels with slow dynamic characteristics and time weights the dose in concert with the standard of interest. In recent years the physical accuracy of noise dosimeter measurements has been questioned by a few acoustical consultants, particularly when rapidly time-varying or impulsive waveforms are encountered. Since noise dosimeters provide simple and economical documentation of employee daily noise exposure for hearing conservation and regulatory compliance purposes a discussion of their accuracy is necessary to clear up any confusion.

  1. Estimating exposure and dose to characterize health risks: the role of human tissue monitoring in exposure assessment.

    PubMed Central

    Sexton, K; Callahan, M A; Bryan, E F

    1995-01-01

    Exposure assessment is an integral part of health risk characterization. Exposure assessments typically address three critical aspects of exposure: the number of people exposed to the environmental toxicant, at specific concentrations, for the time period of interest; the resulting dose; and the relative contribution of important sources and pathways to exposure/dose. Because historically both "point-of-contact" measurements and information about dose and related pharmacokinetic processes have been lacking, exposure assessments have had to rely on construction of "scenarios" to estimate exposure and dose. This could change, however, as advances in development of biologic markers of exposure and dose make it possible to measure and interpret toxicant concentrations in accessible human tissues. The increasing availability of "biomarkers," coupled with improvements in pharmacokinetic understanding, present opportunities to estimate ("reconstruct") exposure from measurements of dose and knowledge of intake and uptake parameters. Human tissue monitoring, however, is not a substitute for more traditional methods of measuring exposure, but rather a complementary approach. A combination of exposure measurements and dose measurements provides the most credible scientific basis for exposure assessment. PMID:7635107

  2. Quantifying traffic exposure.

    PubMed

    Pratt, Gregory C; Parson, Kris; Shinoda, Naomi; Lindgren, Paula; Dunlap, Sara; Yawn, Barbara; Wollan, Peter; Johnson, Jean

    2014-01-01

    Living near traffic adversely affects health outcomes. Traffic exposure metrics include distance to high-traffic roads, traffic volume on nearby roads, traffic within buffer distances, measured pollutant concentrations, land-use regression estimates of pollution concentrations, and others. We used Geographic Information System software to explore a new approach using traffic count data and a kernel density calculation to generate a traffic density surface with a resolution of 50?m. The density value in each cell reflects all the traffic on all the roads within the distance specified in the kernel density algorithm. The effect of a given roadway on the raster cell value depends on the amount of traffic on the road segment, its distance from the raster cell, and the form of the algorithm. We used a Gaussian algorithm in which traffic influence became insignificant beyond 300?m. This metric integrates the deleterious effects of traffic rather than focusing on one pollutant. The density surface can be used to impute exposure at any point, and it can be used to quantify integrated exposure along a global positioning system route. The traffic density calculation compares favorably with other metrics for assessing traffic exposure and can be used in a variety of applications. PMID:24045427

  3. Exposure of Photoresists

    E-print Network

    Yoo, S. J. Ben

    . The absorption spectrum (spectral sensitivity see next section) of AZ® and TI photoresists is matched to this Hg or stepper. The exposure wavelengths of the laser often differs from the 365, 405, or 435 nm Hg lines which sensitivity is matched to the emission spectrum of Hg lamps (i-line = 365 nm, h-line = 405 nm, g-line = 435 nm

  4. SMALL ENGINE EXPOSURE STUDY

    EPA Science Inventory

    A large segment of the population uses small, gasoline powered engines on a regular basis. These small engines include lawn mowers, string trimmers, chainsaws, and snow blowers. Since emissions from many of these engines are not regulated, human exposures may be high, especiall...

  5. An Automatic PZT with Prolonged Exposure

    NASA Astrophysics Data System (ADS)

    Hu, Q. Q.; Guo, R. H.; Liu, M. H.; Xu, Q. G.

    An automatic PZT with prolonged exposure was completed and put into operation at Wuchang Time Observatory of IGG of China in 1986. It is the second PZT designed and made in China, but it is rather different from the first one which is regarded as a traditional PZT. The main characteristics of this PZT are reported here.

  6. DEVELOPING MEANINGFUL COHORTS FOR HUMAN EXPOSURE MODELS

    EPA Science Inventory

    This paper summarizes numerous statistical analyses focused on the U.S. Environmental Protection Agency's Consolidated Human Activity Database (CHAD), used by many exposure modelers as the basis for data on what people do and where they spend their time. In doing so, modelers ...

  7. Transient Response of Cadmium Telluride Modules to Light Exposure: Preprint

    SciTech Connect

    Deline, C.; del Cueto, J.; Albin, D. S.; Petersen, C.; Tyler, L.; TamizhMani, G.

    2011-07-01

    Commercial cadmium telluride (CdTe) photovoltaic (PV) modules from three different manufacturers were monitored for performance changes during indoor and outdoor light-exposure. Short-term transients in Voc were recorded on some modules, with characteristic times of ~1.1 hours. Outdoor performance data shows a similar drop in Voc after early morning light exposure. Preliminary analysis of FF changes show light-induced changes on multiple time scales, including a long time scale.

  8. Exposure ages and erosion rates for lunar rocks

    NASA Technical Reports Server (NTRS)

    Burnett, D. S.; Woolum, D. S.

    1977-01-01

    The available data on the effects of particle bombardment of lunar rocks are examined, taking into account rare gas data, neutron capture products, radioactive nuclei, and particle tracks. Attention is given to exposure ages, questions concerning the validity of exposure ages, the location of rocks during irradiation, the criteria for valid crater ages, special problems regarding lunar breccias, surface residence times from long lived radioactive nuclei, surface residence times from galactic cosmic ray track data, rocks with simple surface exposure, rocks with complex surface exposure, limits on surface residence times, suntan and subdecimeter ages, erosion rates, and a number of case histories related to exposure age measurements as applied to the problem of the dating of impact events.

  9. Dynamic Models for Insect Mortality Due to Exposure to Insecticides

    E-print Network

    models for insecticide induced sublethal damage and delayed death in insect populations are considered for populations subjected to numerous levels of insecticide exposure. The effects on fecundity rates are also examined. Key words: Differential equation models, insect populations, insecticide exposure, time varying

  10. Environmental Exposure Effects on Composite Materials for Commercial Aircraft

    NASA Technical Reports Server (NTRS)

    Hoffman, D. J.

    1980-01-01

    The test program concentrates on three major areas: flight exposure; ground based exposure; and accelerated environmental effects and data correlation. Among the parameters investigated were: geographic location, flight profiles, solar heating effects, ultraviolet degradation, retrieval times, and test temperatures. Data from the tests can be used to effectively plan the cost of production and viable alternatives in materials selection.

  11. Reversible and irreversible modifications of ? -lactoglobulin upon exposure to heat

    Microsoft Academic Search

    Sabina Cairoli; Stefania Iametti; Francesco Bonomi

    1994-01-01

    Modifications in the exposure to the solvent of hydrophobic residues, changes in their organization into surface hydrophobic patches, and alterations in the dimerization equilibrium ofß-lactoglobulin upon thermal treatment at neutralpH were studied. Exposure of tryptophan residues was temperature dependent and was essentially completed on the time scale of seconds. Reorganization of generic hydrophobic protein patches on the protein surface was

  12. Exposure: Why Spatial Context Matters - Geographic Information Systems & Science

    Cancer.gov

    Because many cancers develop over a long period of time, knowing the spatial context throughout a person's life is important to understand his or her total exposure to toxic agents. Recently, scientists have discovered that some cancers are caused by a combination of an underlying genetic abnormality coupled with environmental exposure. Such "gene-environment" interactions further emphasize the importance of spatial context.

  13. Occupational Exposure of Veterinarians to Waste Anesthetic Gases

    Microsoft Academic Search

    David Lionel Potts; Bobby F. Craft

    1988-01-01

    An evaluation of anesthetic waste gas exposures was conducted in small private practice animal clinics throughout the Salt Lake Valley. The two most frequently used anesthetic gases, methoxyflurane and halothane, were chosen to be studied. Exposures during 38 surgeries were studied in a total of 10 facilities involving 13 veterinarians. Veterinarian breathing zones were sampled on a real-time basis with

  14. Chemical process-based reconstruction of exposures for an epidemiological study. Part II. Estimated exposures to chloroprene and vinyl chloride.

    PubMed

    Esmen, Nurtan A; Hall, Thomas A; Phillips, Margaret L; Jones, E Paige; Basara, Heather; Marsh, Gary M; Buchanich, Jeanine M

    2007-03-20

    In a four-facility occupational epidemiology study of chloroprene monomer and polymer production workers, the chloroprene (CD) and vinyl chloride monomer (VCM) exposures were modeled for plant specific job title classes. In two facilities an acetylene-based process was used and in the other two plants only a butadiene-based process was used in the monomer synthesis. In the Acetylene process VCM was an undesirable by-product to be removed. In the newer butadiene-based process, VCM was not involved and the exposures to CD were considerably lower than they were in the earlier years. One of the limiting factors was the operator rotation within a number of job titles. This rotation and inability to differentiate between job titles subsumed in job classifications recorded in the work histories required an exposure classification scheme based on an order of magnitude separation of exposure classes. In the four facilities with considerable variation in the mix of the production methods, the CD exposures were remarkably similar in both calculated and measured values. The reductions in exposures were much more dependent upon the improvement of the production methods, rather than deliberate exposure control for occupational hygiene considerations. This is reasonable since the exposures were generally lower than the coeval exposure limits and/or guidelines. The estimated exposures were less than 100 ppm in the pre-1960 era and less than 10 ppm in the 1960-1980 era, less than 1 ppm 1980-1990 era and less than 0.5 ppm thereafter. The exposures were categorized in four classes for VCM and six classes for CD. The characteristic class exposure values were used to cumulate individual exposures over time with a quantification of the potential range for exposures that are reasonably certain to ascribe correct ranking to job classes. PMID:16989794

  15. DEMONSTRATE AGGREGATE EXPOSURE ANALYSIS USING PESTICIDE EXPOSURE DATA FROM NHEXAS

    EPA Science Inventory

    Under the Food Quality Protection Act, the Agency is required to consider all routes of exposure. However, the procedures to construct these kind of assessments has not been demonstrated largely due to a lack of exposure monitoring data. This project uses the aggregate exposure...

  16. Practical Protective Tools for Occupational Exposure:

    PubMed Central

    Kurokawa, S.; Yabe, S.; Takamura, A.; Ishizaki, H.; Aizawa, S.

    2000-01-01

    Summary Two practical protective tools for occupational exposure for neurointerventional radiologists are presented. The first purpose of this study was to investigate the effectiveness of double focus spectacles for the aged with a highly refracted glass lens (special spectacles for the aged) for radiation protection of the crystalline lens of the eye in comparison with other spectacles on the market, based on the measurement of film density which was obtained by exposure of X-ray through those spectacles. As a result of the film densitometry mentioned above, the effectiveness of special spectacles for the aged in radiation protection was nearly equal to the effectiveness of a goggle type shield which is made with a 0.07 mm lead-equivalent plastic lens. The second purpose of this study was to investigate the effectiveness of the protective barrier; which we remodeled for cerebral angiography or neuroendovascular therapy, for radiation exposure, based on the measurement in a simulated study with a head phantom, and on the measurement of radiation exposure in operaters during procedures of clinical cases. In the experimental study radiation exposure in supposed position of the crystalline lens was reduced to about one third and radiation exposure in supposed position of the gonadal glands was reduced to about one seventh, compared to radiation exposure without employing the barrier. The radiation exposure was monitored at the left breast of three radiologists, in 215 cases of cerebral angiography. Employing the barrier in cerebral angiography, average equivalent dose at the left breast measured 1.49µ Sv during 10 min of fluoroscopy. In three kinds of neuroendovascular therapy in 40 cases, radiation exposure in an operator was monitored in the same fashion and the dose was recorded less than the result reported in previous papers in which any protective barrier have not been employed in the procedure1,2. As a result, the two above mentioned protective tools are considered practical in clinical usage and very effective to reduce radiation exposure in an operator of interventional neuroradiolgy which may sometimes require many hours to complete the therapy under extended fluoroscopic time. PMID:20667219

  17. Neurobehavioral performance in adolescents is inversely associated with traffic exposure.

    PubMed

    Kicinski, Michal; Vermeir, Griet; Van Larebeke, Nicolas; Den Hond, Elly; Schoeters, Greet; Bruckers, Liesbeth; Sioen, Isabelle; Bijnens, Esmée; Roels, Harry A; Baeyens, Willy; Viaene, Mineke K; Nawrot, Tim S

    2015-02-01

    On the basis of animal research and epidemiological studies in children and elderly there is a growing concern that traffic exposure may affect the brain. The aim of our study was to investigate the association between traffic exposure and neurobehavioral performance in adolescents. We examined 606 adolescents. To model the exposure, we constructed a traffic exposure factor based on a biomarker of benzene (urinary trans,trans-muconic acid) and the amount of contact with traffic preceding the neurobehavioral examination (using distance-weighted traffic density and time spent in traffic). We used a Bayesian structural equation model to investigate the association between traffic exposure and three neurobehavioral domains: sustained attention, short-term memory, and manual motor speed. A one standard deviation increase in traffic exposure was associated with a 0.26 standard deviation decrease in sustained attention (95% credible interval: -0.02 to -0.51), adjusting for gender, age, smoking, passive smoking, level of education of the mother, socioeconomic status, time of the day, and day of the week. The associations between traffic exposure and the other neurobehavioral domains studied had the same direction but did not reach the level of statistical significance. The results remained consistent in the sensitivity analysis excluding smokers and passive smokers. The inverse association between sustained attention and traffic exposure was independent of the blood lead level. Our study in adolescents supports the recent findings in children and elderly suggesting that traffic exposure adversely affects the neurobehavioral function. PMID:25461422

  18. Urinary biomarkers of exposure to jet fuel (JP-8).

    PubMed Central

    Serdar, Berrin; Egeghy, Peter P; Waidyanatha, Suramya; Gibson, Roger; Rappaport, Stephen M

    2003-01-01

    Benzene, naphthalene, and 1- and 2-naphthol were measured in urine samples obtained from 322 U.S. Air Force personnel categorized a priori as likely to have low, moderate, or high exposure to jet fuel [jet propulsion fuel-8 (JP-8)]. In postexposure samples, levels of these analytes in the high-exposure group were 3- to 29-fold greater than in the low-exposure group and 2- to 12-fold greater than in the moderate-exposure group. Heavy exposure to JP-8 contributed roughly the same amount of benzene and more than three times the amount of naphthalene compared with cigarette smoking. Strong correlations were observed among postexposure levels of naphthalene-based biomarkers in urine and naphthalene in air and breath. We conclude that urinary naphthalene and the naphthols can serve as biomarkers of exposure to jet fuel. Of these, the naphthols are probably more useful because of their greater abundance and slower elimination kinetics. PMID:14594628

  19. EXPOSURE MODELING OF ACID AEROSOLS

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) is conducting an intensive characterization and human exposure monitoring program of acid species and related air pollutants in an urban environment. he EPA's Atmospheric Research and Exposure Assessment Laboratory (AREAL) in coopera...

  20. Electrothermal controlled-exposure technology

    E-print Network

    Maloney, John Mapes

    2006-01-01

    A technology is presented for exposing the contents of microfabricated cavities in a substrate. These contents are hermetically sealed until exposure is triggered by an electronic signal. The exposure mechanism uses ...

  1. EXPOSURE ANALYSIS MODELING SYSTEM (EXAMS)

    EPA Science Inventory

    The Exposure Analysis Modeling System (EXAMS), first published in 1982 (EPA-600/3-82-023), provides interactive computer software for formulating aquatic ecosystem models and rapidly evaluating the fate, transport, and exposure concentrations of synthetic organic chemicals--pesti...

  2. Characterization of Firefighter Smoke Exposure

    Microsoft Academic Search

    Thomas Z. Fabian; Jacob L. Borgerson; Pravinray D. Gandhi; C. Stuart Baxter; Clara Sue Ross; James E. Lockey; James M. Dalton

    A study of firefighter exposure was undertaken as part of a larger smoke exposure study. Teams of Chicago Fire Department\\u000a firefighters were issued equipment for monitoring exposure conditions during structural fire suppression activity (knockdown\\u000a and overhaul) and search and rescue operations. Potential inhalation exposure was characterized by outfitting firefighters\\u000a with direct-reading gas meters and personal cascade impactors. The gas meters

  3. Estimating worker exposure to power-frequency magnetic fields

    SciTech Connect

    Wenzl, T.B.

    1992-01-01

    For a case-control study of brain cancer at a large automobile transmission plant, a strategy was developed to use two types of instruments to measure personal exposure to power-frequency magnetic fields. A representative group of 81 workers were asked to wear a data-logging dosimeter for one-half shift apiece. This instrument recorded 3-axis magnetic field values every 4 seconds. With little clarity about the biologic process which might connect these magnetic fields to cancer promotion, several indices summarizing exposure variability over time were computed. A new index of [open quotes]jaggedness[close quotes] was also computed, since some human studies suggest very uneven exposure profiles are the most biologically active, possibly via interference with melatonin synthesis in the pineal gland. Comparisons between the several exposure indices showed moderately high correlations between indices which were sensitive to peak exposures, but other indices were less well correlated. To test a simpler measurement strategy, a hand-held direct reading instrument was also used, with multiple measurements taken at the head and waist for most workstations. These were averaged and combined with time estimates to give[open quote] built-up[close quote] average exposures. Correlations were high (r = 0.8) between these built-up averages and averages derived from the datalogger records. It was possible to assign job titles to three distinct exposure categories based on measures of the central tendency of the distributions of measured exposures. By ranking job groups by their average exposures, electricians and non-production grinders were placed in a high exposure category, assemblers and material handlers were placed in a low category, and all other jobs were placed in a medium exposure category. Analysis of variance, with influence analysis, was used to determine that these categories had significant exposure differences from one another.

  4. Correlation of fluorescent tracer measurements of dermal exposure and urinary metabolite excretion during occupational exposure to malathion.

    PubMed

    Fenske, R A

    1988-09-01

    Nineteen workers conducting mixing and high-volume airblast applications of the organophosphorus pesticide malathion were monitored simultaneously by biological monitoring and fluorescent tracer evaluation of dermal exposure. Complete 72-hr urine samples were collected and analyzed for dimethylthiophosphate and dimethyldithiophosphate metabolites. Dermal exposure was measured through the addition of a fluorescent tracer to the tank mix, subsequent examination of the skin surface under long-wave ultraviolet light, and fluorescence quantification with a video imaging system. Dermal exposure to applicators was correlated highly with total metabolite excretion (r = 0.91). Mixer exposure was not correlated significantly (r = 0.73) because of wide scatter in the data and the small number of workers monitored. Applicator exposures were more than 3 times higher than mixer exposures, reflecting the high exposure potential inherent in airblast spraying. Exposure to regions protected by gloves or clothing was more than 75% of total exposure for both mixers and applicators. These results provide evidence that the fluorescent tracer technique is a valid methodology for measuring relative levels of dermal exposure during agricultural work activities. The technique also holds promise as a quantitative procedure for evaluating the effectiveness of engineering control strategies and protective clothing performance. PMID:3177222

  5. Radiation exposure to anaesthetists during endovascular procedures.

    PubMed

    Arii, T; Uchino, S; Kubo, Y; Kiyama, S; Uezono, S

    2015-01-01

    Medical radiation exposure increases the likelihood of cataract formation. A personal dosimeter was attached to the left temple of 77 anaesthetists during 45 endovascular aortic aneurysm repairs and 32 interventional neuroradiology procedures. Compared with interventional neuroradiology, the median (IQR [range]) total radiation dose emitted by fluoroscopic equipment was significantly lower during endovascular aortic aneurysm repair (4175 (3127-5091 [644-9761]) mGy than interventional neuroradiology (1420 (613-2424 [165-10,840]) mGy, p < 0.001). However, radiation exposure to the anaesthetist's temple was significantly greater during endovascular aortic aneurysm repair (15 (6-41 [1-109]) ?Sv) than interventional neuroradiology (4 (2-8 [0-67]) ?Sv, p < 0.001). These data suggest that anaesthetists at our institution would have to deliver anaesthesia for ~1300 endovascular aortic aneurysm repairs and ~5000 interventional neuroradiology cases annually to exceed the general occupational limits, and ~10,000 endovascular aortic aneurysm repairs and ~37,500 interventional neuroradiology cases to exceed the ocular exposure limits recommended by the International Commission on Radiological Protection. Nevertheless, anaesthetists should be aware of the risk of ocular radiation exposure, and reduce this by limiting the time of exposure, increasing the distance from the source of radiation, and shielding. PMID:25267714

  6. Bloodborne Pathogens Exposure Control Plan.

    ERIC Educational Resources Information Center

    National Child Care Association, Atlanta, GA.

    This sample exposure control plan is a guide to assist child care providers in complying with the blood-borne pathogens standard issued by the Occupational Safety and Health Administration (OSHA). The standard requires employers to establish a written exposure control plan by May 5, 1992 (for exposure to microorganisms in human blood that cause…

  7. EPA'S HUMAN EXPOSURE MEASUREMENT PROGRAM

    EPA Science Inventory

    The goal of NERL's Exposure Research Program is to improve the scientific basis for conducting human exposure assessments that are part of the EPA's risk assessment, risk management and compliance process. Overall, we aim to address aggregate and cumulative exposures that pose...

  8. DIETARY EXPOSURE METHODS AND MODELS

    EPA Science Inventory

    The research reported in this task description constitutes the MCEARD base dietary exposure research program and is conducted to complement the NERL aggregate and cumulative exposure program. Its purpose is to reduce the level of uncertainty in exposure assessment by improving N...

  9. AIR TOXICS HUMAN EXPOSURE MODELING

    EPA Science Inventory

    This project aims to improve the scientific basis for the Environmental Protection Agency's (EPA's) assessments of human exposures to air toxics by developing improved human exposure models. The research integrates the major components of the exposure paradigm, i.e., sources, tr...

  10. Adenocarcinoma of the stomach and exposure to occupational dust

    SciTech Connect

    Wright, W.E.; Bernstein, L.; Peters, J.M.; Garabrant, D.H.; Mack, T.M.

    1988-07-01

    The authors studied 1342 cases of adenocarcinoma of the stomach identified by a population-based cancer registry in Los Angeles County, California. The cases were males aged 20-64 years first diagnosed between 1972 and 1982. To determine whether exposure to occupational dust increased the risk of developing stomach cancer, occupational titles were rated for the likelihood of exposure to various kinds of dust. Men who worked in dusty jobs had a risk for developing stomach cancer 1.3 times that of unexposed men. The association of exposure to dust with stomach cancer was stronger at higher levels of exposure. The risk was not uniform throughout the stomach: the highest risk (1.8 times that of unexposed men) was found for the antrum/pylorus. At that site, exposure to mineral dust carried the greatest risk for cancer (3.7 times the risk for unexposed men). The highest risks from dust exposure were observed in blacks. Risk was related to race, socioeconomic status, and immigrant status, but these factors did not entirely explain the association with dust exposure. The observed relation between dust exposure and stomach cancer is consistent with results of previous mortality and case-control studies of cancer in men who worked in dusty occupations. Ingested dust may be one factor in the etiology of adenocarcinoma of the stomach.

  11. Exposure to particles from laser printers operating within office workplaces.

    PubMed

    McGarry, Peter; Morawska, Lidia; He, Congrong; Jayaratne, Rohan; Falk, Matthew; Tran, Quang; Wang, Hao

    2011-08-01

    While recent research has provided valuable information as to the composition of laser printer particles, their formation mechanisms, and explained why some printers are emitters while others are low emitters, questions relating to the potential exposure of office workers remained unanswered. In particular, (i) what impact does the operation of laser printers have on the background particle number concentration (PNC) of an office environment over the duration of a typical working day? (ii) What is the airborne particle exposure to office workers in the vicinity of laser printers? (iii) What influence does the office ventilation have upon the transport and concentration of particles? (iv) Is there a need to control the generation of, and/or transport of particles arising from the operation of laser printers within an office environment? (v) What instrumentation and methodology is relevant for characterizing such particles within an office location? We present experimental evidence on printer temporal and spatial PNC during the operation of 107 laser printers within open plan offices of five buildings. The 8 h time-weighted average printer particle exposure is significantly less than the 8 h time-weighted local background particle exposure, but that peak printer particle exposure can be greater than 2 orders of magnitude higher than local background particle exposure. The particle size range is predominantly ultrafine (<100 nm diameter). In addition we have established that office workers are constantly exposed to nonprinter derived particle concentrations, with up to an order of magnitude difference in such exposure among offices, and propose that such exposure be controlled along with exposure to printer derived particles. We also propose, for the first time, that peak particle reference values be calculated for each office area analogous to the criteria used in Australia and elsewhere for evaluating exposure excursion above occupational hazardous chemical exposure standards. A universal peak particle reference value of 2.0 × 10(4) particles cm(-3) has been proposed. PMID:21662984

  12. Simultaneous occupational exposure to FM and UHF transmitters.

    PubMed

    Vali?, Blaž; Kos, Bor; Gajšek, Peter

    2012-01-01

    Occupational exposure caused by large broadcasting transmitters exceeds current reference levels. As it is common for different radio and TV transmitters to share the location, we analysed combined exposure on a 40-m high mast. The frequency modulation (FM) transmitter, located between the 10th and 30th metre, had the power of 25 kW, whereas an ultra-high frequency (UHF) transmitter of 5 kW occupied the top 8 m of the mast. Measured and calculated values of the electric field strength exceeded the reference levels up to 10 times; however, the results for the specific absorption rate (SAR) values show that the reference levels are very conservative for FM exposure, i.e., basic restrictions are not exceeded even when the reference levels are exceeded 10 times. However, for UHF exposure the reference levels are not conservative; they give a good prediction of real exposure. PMID:22721535

  13. Monitoring wild bird populations for lead exposure

    SciTech Connect

    Scheuhammer, A.M. (Environment Canada, Ottawa (Canada))

    1989-07-01

    Delta-aminolevulinic acid dehydratase (ALA-d), an enzyme in the heme biosynthetic pathway is extremely sensitive to inhibition by lead (Pb). I evaluated the erythrocyte ALA-d activity ratio (the ratio between the fully restored enzyme activity and that measured without removing any inhibitory influence that might be present) as an indicator of Pb exposure in free-living birds. In the absence of elevated Pb exposure, birds, had comparable ALA-d activity ratios regardless of species, geographical location, or time of year sampled. The normal range of ratios for free-living species was similar to that for aviary-raised birds (1.0-1.3). Individuals with enzyme inhibition were readily identified. In blood collected from free-living mallards (Anas platyrhynchos), ALA-d activity ratios were better correlated with blood-Pb than were blood-protoporphyrin (PP) concentrations. At least 9.5% of mallards with blood-Pb>80 {mu}g/dL did not have elevated PP levels. Underestimation of Pb exposure did not occur using the ALA-d activity ratio method. The ALA-d activity ratio was as accurate as blood-Pb measurements for monitoring the relative degree of recent Pb exposure in the wild bird populations studied. Unlike blood-Pb analyses, ALA-d determinations do not require exposure in the wild bird populations studied. Unlike blood-Pb analyses, ALA-d determinations do not require exposure in the wild bird populations studied. Unlike blood-Pb analyses, ALA-d determinations do not require sophisticated and expensive instrumentation, and assays can be performed efficiently with minimal training.

  14. Human exposure to urban air pollution.

    PubMed Central

    Boström, C E; Almén, J; Steen, B; Westerholm, R

    1994-01-01

    This study deals with some methods of making human exposure estimates, aimed at describing the human exposure for selected air pollutants in Sweden that are suspected carcinogens. Nitrogen oxides (NOx) have been chosen as an indicator substance for estimating the concentration of the urban plume. Earlier investigations have shown that the traffic in Swedish cities contributes around 85% to the measured NOx concentrations, and that most of the mutagenicity in urban air originates from traffic. The first section of this paper describes measurements in Stockholm of some unregulated light hydrocarbons, such as ethene, ethyne, propane, propene, butane, and isobutane. In addition, measurements of some volatile aromatic hydrocarbons are presented. Simultaneous measurements of carbon monoxide (CO) were made. The ratios between CO and the individual specific compounds were determined by linear regression analysis. By analysis of relationships between CO and NOx, NOx concentrations can be used as a tracer to describe the exposure for these specific compounds. NOx are considered to be a better tracer than CO, because NOx or NO2 values exist for many places over a long time, while CO is measured mostly in streets with high concentrations. At low concentrations, instruments that measure normal CO levels give no detectable signals. Through use of atmospheric dispersion models and models that describe how people live and work in urban areas it has been possible to describe the average exposure to NOx in cities of different sizes. The exposure to NOx for people living in the countryside has also been estimated. In this way, it has been possible to calculate the average exposure dose for NOx for the Swedish population. This figure is 23 micrograms/m3. By use of the relationships between NOx and specific compounds the average dose has been calculated for the following compounds: polyaromatic compounds (PAH); ethene, propene, and butadiene; benzene, toluene, and xylene; formaldehyde and actaldehyde; nickel, chromium (VI), arsenic, and cadmium; asbestos; and silicon. PMID:7821294

  15. Hard metal exposures. Part 2: Prospective exposure assessment.

    PubMed

    Simcox, N J; Stebbins, A; Guffey, S; Atallah, R; Hibbard, R; Camp, J

    2000-04-01

    Hard metal exposures may precipitate lung disease in exposed workers. This article reports on a project investigating the relationship between local exhaust hood air flow levels and workplace hard metal exposures. Airborne cobalt, chromium, and cadmium exposure concentrations, and ventilation system function were monitored for three consecutive days prior to installation of three new ventilation systems, and then were followed monthly for one year. Work activities included wet and dry grinding of saw blades, brazing, welding, and setup. Work task exposures were highly variable over the period of the study. Ventilation air flows failed to meet design goals due to low total air volume and poor distribution; however, worker exposures to metals were controlled in most cases. Hood design, worker acceptance, and use of the hoods were as important in controlling exposures as were exhaust hood air flow levels. PMID:10750278

  16. Semen quality in papaya workers with long term exposure to ethylene dibromide

    Microsoft Academic Search

    J M Ratcliffe; S M Schrader; K Steenland; D E Clapp; T Turner; R W Hornung

    1987-01-01

    To examine whether long term occupational exposure to ethylene dibromide (EDB) affects semen quality a cross sectional study of semen quality was conducted among 46 men employed in the papaya fumigation industry in Hawaii, with an average duration of exposure of five years and a geometric mean breathing zone exposure to airborne EDB of 88 ppb (eight hour time weighted

  17. Chronic particulate exposure, mortality and cardiovascular outcomes in the nurses health study

    EPA Science Inventory

    Adverse health effects of exposures to acute air pollution have been well studied. Fewer studies have examined effects of chronic exposure. Previous studies used exposure estimates for narrow time periods and were limited by the geographic distribution of pollution monitors. This...

  18. Exposure assessment approaches to evaluate respiratory health effects of particulate matter and nitrogen dioxide

    Microsoft Academic Search

    J. J. Quackenboss; M. Krzyzanowski; M. D. Lebowitz

    1991-01-01

    Several approaches can be taken to estimate or classify total personal exposures to air pollutants. While personal exposure monitoring (PEM) provides the most direct measurements, it is usually not practical for extended time periods or large populations. This paper describes the use of indirect approaches to estimate total personal exposure for NO2 and particulate matter (PM), summarizes the distributions of

  19. SHEDS-HT: an integrated probabilistic exposure model for prioritizing exposures to chemicals with near-field and dietary sources.

    PubMed

    Isaacs, Kristin K; Glen, W Graham; Egeghy, Peter; Goldsmith, Michael-Rock; Smith, Luther; Vallero, Daniel; Brooks, Raina; Grulke, Christopher M; Özkaynak, Halûk

    2014-11-01

    United States Environmental Protection Agency (USEPA) researchers are developing a strategy for high-throughput (HT) exposure-based prioritization of chemicals under the ExpoCast program. These novel modeling approaches for evaluating chemicals based on their potential for biologically relevant human exposures will inform toxicity testing and prioritization for chemical risk assessment. Based on probabilistic methods and algorithms developed for The Stochastic Human Exposure and Dose Simulation Model for Multimedia, Multipathway Chemicals (SHEDS-MM), a new mechanistic modeling approach has been developed to accommodate high-throughput (HT) assessment of exposure potential. In this SHEDS-HT model, the residential and dietary modules of SHEDS-MM have been operationally modified to reduce the user burden, input data demands, and run times of the higher-tier model, while maintaining critical features and inputs that influence exposure. The model has been implemented in R; the modeling framework links chemicals to consumer product categories or food groups (and thus exposure scenarios) to predict HT exposures and intake doses. Initially, SHEDS-HT has been applied to 2507 organic chemicals associated with consumer products and agricultural pesticides. These evaluations employ data from recent USEPA efforts to characterize usage (prevalence, frequency, and magnitude), chemical composition, and exposure scenarios for a wide range of consumer products. In modeling indirect exposures from near-field sources, SHEDS-HT employs a fugacity-based module to estimate concentrations in indoor environmental media. The concentration estimates, along with relevant exposure factors and human activity data, are then used by the model to rapidly generate probabilistic population distributions of near-field indirect exposures via dermal, nondietary ingestion, and inhalation pathways. Pathway-specific estimates of near-field direct exposures from consumer products are also modeled. Population dietary exposures for a variety of chemicals found in foods are combined with the corresponding chemical-specific near-field exposure predictions to produce aggregate population exposure estimates. The estimated intake dose rates (mg/kg/day) for the 2507 chemical case-study spanned 13 orders of magnitude. SHEDS-HT successfully reproduced the pathway-specific exposure results of the higher-tier SHEDS-MM for a case-study pesticide and produced median intake doses significantly correlated (p<0.0001, R2=0.39) with medians inferred using biomonitoring data for 39 chemicals from the National Health and Nutrition Examination Survey (NHANES). Based on the favorable performance of SHEDS-HT with respect to these initial evaluations, we believe this new tool will be useful for HT prediction of chemical exposure potential. PMID:25222184

  20. Quantifying commuter exposures to volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Kayne, Ashleigh

    Motor-vehicles can be a predominant source of air pollution in cities. Traffic-related air pollution is often unavoidable for people who live in populous areas. Commuters may have high exposures to traffic-related air pollution as they are close to vehicle tailpipes. Volatile organic compounds (VOCs) are one class of air pollutants of concern because exposure to VOCs carries risk for adverse health effects. Specific VOCs of interest for this work include benzene, toluene, ethylbenzene, and xylenes (BTEX), which are often found in gasoline and combustion products. Although methods exist to measure time-integrated personal exposures to BTEX, there are few practical methods to measure a commuter's time-resolved BTEX exposure which could identify peak exposures that could be concealed with a time-integrated measurement. This study evaluated the ability of a photoionization detector (PID) to measure commuters' exposure to BTEX using Tenax TA samples as a reference and quantified the difference in BTEX exposure between cyclists and drivers with windows open and closed. To determine the suitability of two measurement methods (PID and Tenax TA) for use in this study, the precision, linearity, and limits of detection (LODs) for both the PID and Tenax TA measurement methods were determined in the laboratory with standard BTEX calibration gases. Volunteers commuted from their homes to their work places by cycling or driving while wearing a personal exposure backpack containing a collocated PID and Tenax TA sampler. Volunteers completed a survey and indicated if the windows in their vehicle were open or closed. Comparing pairs of exposure data from the Tenax TA and PID sampling methods determined the suitability of the PID to measure the BTEX exposures of commuters. The difference between BTEX exposures of cyclists and drivers with windows open and closed in Fort Collins was determined. Both the PID and Tenax TA measurement methods were precise and linear when evaluated in the laboratory using standard BTEX gases. The LODs for the Tenax TA sampling tubes (determined with a sample volume of 1,000 standard cubic centimeters which is close to the approximate commuter sample volumes collected) were orders of magnitude lower (0.04 to 0.7 parts per billion (ppb) for individual compounds of BTEX) compared to the PIDs' LODs (9.3 to 15 ppb of a BTEX mixture), which makes the Tenax TA sampling method more suitable to measure BTEX concentrations in the sub-parts per billion (ppb) range. PID and Tenax TA data for commuter exposures were inversely related. The concentrations of VOCs measured by the PID were substantially higher than BTEX concentrations measured by collocated Tenax TA samplers. The inverse trend and the large difference in magnitude between PID responses and Tenax TA BTEX measurements indicates the two methods may have been measuring different air pollutants that are negatively correlated. Drivers in Fort Collins, Colorado with closed windows experienced greater time-weighted average BTEX exposures than cyclists (p: 0.04). Commuter BTEX exposures measured in Fort Collins were lower than commuter exposures measured in prior studies that occurred in larger cities (Boston and Copenhagen). Although route and intake may affect a commuter's BTEX dose, these variables are outside of the scope of this study. Within the limitations of this study (including: small sample size, small representative area of Fort Collins, and respiration rates not taken into account), it appears health risks associated with traffic-induced BTEX exposures may be reduced by commuting via cycling instead of driving with windows closed and living in a less populous area that has less vehicle traffic. Although the PID did not reliably measure low-level commuter BTEX exposures, the Tenax TA sampling method did. The PID measured BTEX concentrations reliably in a controlled environment, at high concentrations (300-800 ppb), and in the absence of other air pollutants. In environments where there could be multiple chemicals present that may produce a PID signal (such a

  1. Pesticides re-entry dermal exposure of workers in greenhouses.

    PubMed

    Caffarelli, V; Conte, E; Correnti, A; Gatti, R; Musmeci, F; Morali, G; Spagnoli, G; Tranfo, G; Triolo, L; Vita, M; Zappa, G

    2004-01-01

    This research has the aim to evaluate the risk of pesticide dermal exposure for workers in greenhouses. We considered the following crops: tomato, cucumber and strawberry, largely spread in Bracciano lake district. The pesticides monitored were: tetradifon on strawberry: metalaxyl, azoxystrobin and fenarimol on cucumber; acrinathrin, azoxystrobin and chlorpyrifos ethyl on tomato. The dermal exposure was evaluated by Dislodgeable Foliar Residue (DFR) measurements employing transfer coefficients got from literature. For risk evaluation, we have compared the dermal exposures with Acceptable Operator Exposure Levels (AOEL). The re-entry time were obtained intercepting the dose decay curves with AOEL values. The re-entry times result higher than two days in the cases of chlorpyrifos on tomato (re-entry time: 3 days), azoxystrobin on tomato (4 days), and tetradifon on strawberry (8 days). The need of measuring specific transfer coefficients is pointed out. PMID:15756864

  2. Exposure assessment for power frequency electric and magnetic fields.

    PubMed

    Bracken, T D

    1993-04-01

    Over the past decade considerable data have been collected on electric and magnetic fields in occupational environments. These data have taken the form of area measurements, source characterizations, and personal exposure measurements. Occupational EMF levels are highly variable in space and time. Exposures associated with these fields exhibit similar large variations during a day, between days, and between individuals within a group. The distribution of exposure measures is skewed over several decades with only a few values occurring at the maximum field levels. The skewness of exposure measures implies that large sample sizes may be required for assessments and that multiple statistical descriptors are preferred to describe individual and group exposures. Except for the relatively few occupational settings where high voltage sources are prevalent, electric fields encountered in the workplace are probably similar to residential exposures. Consequently, high electric field exposures are essentially limited to utility environments and occupations. Within the electric utility industry, it is definitely possible to identify occupations with high electric field exposures relative to those of office workers or other groups. The highly exposed utility occupations are linemen, substation operators, and utility electricians. The distribution of electric field exposures in the utility worker population is very skewed even within a given occupation. As with electric fields, magnetic fields in the workplace appear to be comparable with residential levels, unless a clearly defined high-current source is present. Since high-current sources are more prevalent than high-voltage sources, environments with relatively high magnetic field exposures encompass a more diverse set of occupations than do those with high electric fields. Within the electric utility industry, it is possible to identify occupational environments with high magnetic field exposure relative to the office environment. Utility job categories with the highest exposures are generation facility workers, substation operators, utility linemen, and utility electricians. There are also higher exposures among traditional "electrical worker" job categories. Outside the electrical utility industry, potential sources of high occupational magnetic field exposures at ELF are induction furnaces, welding machines, electrical transportation systems, and electrical distribution vaults. However, the use of low power electrical equipment such as small motors in close proximity to workers and possibly for long periods of time could also lead to high exposure situations. Handheld survey instruments are available to perform area measurements of electric and magnetic fields at power frequencies but not aat all frequencies within the ELF range. Sophisticated personal computer-based instruments are available to characterize areas and sources across the entire frequency range.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8480632

  3. Extrapulmonary transport of MWCNT following inhalation exposure

    PubMed Central

    2013-01-01

    Background Inhalation exposure studies of mice were conducted to determine if multi-walled carbon nanotubes (MWCNT) distribute to the tracheobronchial lymphatics, parietal pleura, respiratory musculature and/or extrapulmonary organs. Male C57BL/6 J mice were exposed in a whole-body inhalation system to a 5 mg/m3 MWCNT aerosol for 5 hours/day for 12 days (4 times/week for 3 weeks, lung burden 28.1 ug/lung). At 1 day and 336 days after the 12 day exposure period, mice were anesthetized and lungs, lymph nodes and extrapulmonary tissues were preserved by whole body vascular perfusion of paraformaldehyde while the lungs were inflated with air. Separate, clean-air control groups were studied at 1 day and 336 days post-exposure. Sirius Red stained sections from lung, tracheobronchial lymph nodes, diaphragm, chest wall, heart, brain, kidney and liver were analyzed. Enhanced darkfield microscopy and morphometric methods were used to detect and count MWCNT in tissue sections. Counts in tissue sections were expressed as number of MWCNT per g of tissue and as a percentage of total lung burden (Mean?±?S.E., N?=?8 mice per group). MWCNT burden in tracheobronchial lymph nodes was determined separately based on the volume density in the lymph nodes relative to the volume density in the lungs. Field emission scanning electron microscopy (FESEM) was used to examine MWCNT structure in the various tissues. Results Tracheobronchial lymph nodes were found to contain 1.08 and 7.34 percent of the lung burden at 1 day and 336 days post-exposure, respectively. Although agglomerates account for approximately 54% of lung burden, only singlet MWCNT were observed in the diaphragm, chest wall, liver, kidney, heart and brain. At one day post exposure, the average length of singlet MWCNT in liver and kidney, was comparable to that of singlet MWCNT in the lungs 8.2?±?0.3 versus 7.5?±?0.4 um, respectively. On average, there were 15,371 and 109,885 fibers per gram in liver, kidney, heart and brain at 1 day and 336 days post-exposure, respectively. The burden of singlet MWCNT in the lymph nodes, diaphragm, chest wall and extrapulmonary organs at 336 days post-exposure was significantly higher than at 1 day post-exposure. Conclusions Inhaled MWCNT, which deposit in the lungs, are transported to the parietal pleura, the respiratory musculature, liver, kidney, heart and brain in a singlet form and accumulate with time following exposure. The tracheobronchial lymph nodes contain high levels of MWCNT following exposure and further accumulate over nearly a year to levels that are a significant fraction of the lung burden 1 day post-exposure. PMID:23927530

  4. Exposure to ultrafine and fine particles and noise during cycling and driving in 11 Dutch cities

    Microsoft Academic Search

    Hanna Boogaard; Frank Borgman; Jaap Kamminga; Gerard Hoek

    2009-01-01

    Recent studies have suggested that exposures during traffic participation may be associated with adverse health effects. Traffic participation involves relatively short but high exposures. Potentially relevant exposures include ultrafine particles, fine particles (PM2.5) and noise.Simultaneously, detailed real time exposure of particle number concentration (PNC), PM2.5 and noise has been measured while driving and cycling 12 predefined routes of approximately 10–20 min

  5. [Radiodiagnostic features of the pulmonary form of Q fever].

    PubMed

    Asiku, V

    1989-01-01

    Patients with the pulmonary form of Q fever and the more rarely described pleural reaction were presented. The purpose of this work was as follows: to pay attention to all characteristics of the radiological picture of the pulmonary form of Q fever, to emphasize the importance of the radiological finding for the establishment of diagnosis, to point to the present possibilities of radiology and to put forward diagnostic procedures. Namely, when managing the patients in clinical practice, radiological examination is performed almost in the first place, the referring diagnosis is most frequently optional, while clinical and laboratory findings are still incomplete and not always useful. Thus, the diagnostic procedure of radiologists is made much more difficult, particularly of those who have not had the chance of encountering these diseases in their everyday radiologic diagnostic. However, recent knowledge of some authors who have investigated these diseases in the territory of SAP of Vojvodina points to the fact that percentually Q fever most frequently appears just in this territory when compared with other parts of SFR of Yugoslavia. Anyhow, according to the results obtained, the incidence of diseases is greater than the majority of radiologists could conclude in their everyday clinical practice. This necessitates the refreshment of knowledge in this field which would lead toward further improvement of diagnostic. PMID:2761477

  6. Domestic Asbestos Exposure: A Review of Epidemiologic and Exposure Data

    PubMed Central

    Goswami, Emily; Craven, Valerie; Dahlstrom, David L.; Alexander, Dominik; Mowat, Fionna

    2013-01-01

    Inhalation of asbestos resulting from living with and handling the clothing of workers directly exposed to asbestos has been established as a possible contributor to disease. This review evaluates epidemiologic studies of asbestos-related disease or conditions (mesothelioma, lung cancer, and pleural and interstitial abnormalities) among domestically exposed individuals and exposure studies that provide either direct exposure measurements or surrogate measures of asbestos exposure. A meta-analysis of studies providing relative risk estimates (n = 12) of mesothelioma was performed, resulting in a summary relative risk estimate (SRRE) of 5.02 (95% confidence interval [CI]: 2.48–10.13). This SRRE pertains to persons domestically exposed via workers involved in occupations with a traditionally high risk of disease from exposure to asbestos (i.e., asbestos product manufacturing workers, insulators, shipyard workers, and asbestos miners). The epidemiologic studies also show an elevated risk of interstitial, but more likely pleural, abnormalities (n = 6), though only half accounted for confounding exposures. The studies are limited with regard to lung cancer (n = 2). Several exposure-related studies describe results from airborne samples collected within the home (n = 3), during laundering of contaminated clothing (n = 1) or in controlled exposure simulations (n = 5) of domestic exposures, the latter of which were generally associated with low-level chrysotile-exposed workers. Lung burden studies (n = 6) were also evaluated as a surrogate of exposure. In general, available results for domestic exposures are lower than the workers’ exposures. Recent simulations of low-level chrysotile-exposed workers indicate asbestos levels commensurate with background concentrations in those exposed domestically. PMID:24185840

  7. Complex chlorinated hydrocarbons: occupational exposure in the sawmill industry.

    PubMed

    Kalliokoski, P; Kauppinen, T

    1990-01-01

    Exposure to chlorophenols occurs in the vicinity of the lumber treatment area in sawmills and in subsequent work phases where treated lumber is handled. Measurements from several countries indicate that the concentration of chlorophenols in the workroom air is generally below 0.5 mg/m3, the occupational exposure limit of chlorophenols in many countries. Inhalation usually leads to relatively low concentrations of chlorophenols in urine of exposed workers. Frequent skin contact with chlorophenol solution or with freshly treated lumber can produce urine concentrations 10-100 times higher than among those with inhalatory exposure only. In addition to chlorophenols, exposure to toxic polychlorinated dibenzodioxins and dibenzofurans may occur in some tasks carried out in sawmills. Jobs with potentially heavy exposure include the treatment of dipping-vat sludge and processes involving heating of chlorophenols, such as burning of treated waste wood and welding of metal structures contaminated by chlorophenols. PMID:2228138

  8. Bayesian hierarchical modeling of personal exposure to particulate matter

    NASA Astrophysics Data System (ADS)

    McBride, Sandra J.; Williams, Ron W.; Creason, John

    In the US EPA's 1998 Baltimore Epidemiology-Exposure Panel Study, a group of 16 residents of a single building retirement community wore personal monitors recording personal fine particulate air pollution concentrations (PM 2.5) for 27 days, while other monitors recorded concurrent apartment, central indoor, outdoor and ambient site PM 2.5 concentrations. Using the Baltimore panel study data, we develop a Bayesian hierarchical model to characterize the relationship between personal exposure and concentrations of PM 2.5 indoors and outdoors. Personal exposure is expressed as a linear combination of time spent in microenvironments and associated microenvironmental concentrations. The model incorporates all available monitoring data and accounts for missing data and sources of uncertainty such as measurement error and individual differences in exposure. We discuss the implications of using personal versus ambient PM 2.5 measurements in characterization of personal exposure to PM 2.5.

  9. Occupational exposure to elemental constituents in fingerprint powders

    SciTech Connect

    Van Netten, C.; Souter, F.; Teschke, K.E. (Univ. of British Columbia, Vancouver (Canada))

    1990-03-01

    Fingerprint detection is an essential component of any crime detection agency. Little information is available regarding the elemental constituents of powders that are available currently. One recent case of lead poisoning coupled with many complaints from the Vancouver identification Squad members initiated a study regarding the elemental composition of, and the occupational exposure to, these powders. Multi-elemental analysis of the powders investigated showed that all contained varying amounts of aluminum, calcium, zinc, iron, magnesium, manganese, and nickel. One powder, however, contained 41% lead. The time spent at the scene of crime during a normal working shift averaged 95.5 min. Assessment of inhalation exposure during this period by personal air sampling pumps never exceeded the occupational exposure standards for these elements. Secondary exposure from dust-contaminated police vehicles and clothing can be an important contributor to overall exposure.

  10. Neurobehavioral risk is associated with gestational exposure to stress hormones

    PubMed Central

    Sandman, Curt A; Davis, Elysia Poggi

    2012-01-01

    The developmental origins of disease or fetal programming model predict that early exposures to threat or adverse conditions have lifelong consequences that result in harmful outcomes for health. The maternal endocrine ‘fight or flight’ system is a source of programming information for the human fetus to detect threats and adjust their developmental trajectory for survival. Fetal exposures to intrauterine conditions including elevated stress hormones increase the risk for a spectrum of health outcomes depending on the timing of exposure, the timetable of organogenesis and the developmental milestones assessed. Recent prospective studies, reviewed here, have documented the neurodevelopmental consequences of fetal exposures to the trajectory of stress hormones over the course of gestation. These studies have shown that fetal exposures to biological markers of adversity have significant and largely negative consequences for fetal, infant and child emotional and cognitive regulation and reduced volume in specific brain structures. PMID:23144647

  11. Asbestos exposure and neoplasia

    SciTech Connect

    Selikoff, I.J.; Churg, J.; Hammond, E.C.

    1984-07-06

    Builiding trades insulation workers have relatively light, intermittent, exposure to asbestos. Of 632 insulation workers, who entered the trade before 1943 and were traced through 1962, forty-five died of cancer of the lung or pleura, whereas only 6.6 such deaths were expected. Three of the pleural tumors were mesotheliomas; there was also one peritoneal mesothelioma. Four mesotheliomas in a total of 255 deaths is an exceedingly high incidence for such a rare tumor. In addition, an unexpectedly large number of men died of cancer of the stomach, colon, or rectum (29 compared with 9.4 expected). Other cancers were not increased; 20.5 were expected, 21 occurred. Twelve men died of asbestosis. This landmark article appeared originally in this journal 188:22-26, 1964.

  12. EXCOMP: an exposure comparison methodology

    SciTech Connect

    Lavender, J.C.; Franklin, A.L.

    1986-06-01

    EXCOMP is a computerized model that was developed to project occupational exposures based on conceptual designs for the Monitored Retrievable Storage (MRS) Facility. EXCOMP was developed to identify locations and operations in the facility that have a potential for significant occupational exposure rates. Unlike the computerized models that are currently used, EXCOMP is fast and provides the analyst more analysis flexibility. The analyst has the option of evaluating the occupational exposures for an entire facility, specific work locations, personnel profiles based on employees' job descriptions, or the exposure potential of specific identified sources. Comparative analyses can be performed rapidly by initially analyzing the occupational exposures for a facility or a personnel profile and then modifying the database for selected specific work or source locations. EXCOMP was developed to provide the analyst a took that can be used to perform integrated facility evaluations of occupational and public exposures. EXCOMP provides estimates of exposure rates for the purpose of identifying areas with high exposure potential. These areas can be further evaluated using existing detailed exposure modeling computer codes or by performing ''hands on'' monitoring.

  13. Maternal hurricane exposure and fetal distress risk.

    PubMed

    Zahran, Sammy; Snodgrass, Jeffrey G; Peek, Lori; Weiler, Stephan

    2010-10-01

    Logistic regression and spatial analytic techniques are used to model fetal distress risk as a function of maternal exposure to Hurricane Andrew. First, monthly time series compare the proportion of infants born distressed in hurricane affected and unaffected areas. Second, resident births are analyzed in Miami-Dade and Broward counties, before, during, and after Hurricane Andrew. Third, resident births are analyzed in all Florida locales with 100,000 or more persons, comparing exposed and unexposed gravid females. Fourth, resident births are analyzed along Hurricane Andrew's path from southern Florida to northeast Mississippi. Results show that fetal distress risk increases significantly with maternal exposure to Hurricane Andrew in second and third trimesters, adjusting for known risk factors. Distress risk also correlates with the destructive path of Hurricane Andrew, with higher incidences of fetal distress found in areas of highest exposure intensity. Hurricane exposed African-American mothers were more likely to birth distressed infants. The policy implications of?in utero?costs of natural disaster exposure are discussed. PMID:20626684

  14. Mitigating residential exposure to secondhand tobacco smoke

    NASA Astrophysics Data System (ADS)

    Klepeis, Neil E.; Nazaroff, William W.

    In a companion paper, we used a simulation model to explore secondhand tobacco smoke (SHS) exposures for typical conditions in residences. In the current paper, we extend this analysis to evaluate the effectiveness of physical mitigation approaches in reducing nonsmokers' exposure to airborne SHS particulate matter in a hypothetical 6-zone house. Measures investigated included closing doors or opening windows in response to smoking activity, modifying location patterns to segregate the nonsmoker and the active smoker, and operating particle filtration devices. We first performed 24 scripted simulation trials using hypothetical patterns of occupant location. We then performed cohort simulation trials across 25 mitigation scenarios using over 1000 pairs of nonsmoker and smoker time-location patterns that were selected from a survey of human activity patterns in US homes. We limited cohort pairs to cases where more than 10 cigarettes were smoked indoors at home each day and the nonsmoker was at home for more than two thirds of the day. We evaluated the effectiveness of each mitigation approach by examining its impact on the simulated frequency distribution of residential SHS particle exposure. The two most effective strategies were the isolation of the smoker in a closed room with an open window, and a ban on smoking whenever the nonsmoker was at home. The use of open windows to supply local or cross ventilation, or the operation of portable filtration devices in smoking rooms, provided moderate exposure reductions. Closed doors, by themselves, were not effective.

  15. Nonoccupational noise: exposures associated with routine activities

    NASA Astrophysics Data System (ADS)

    Neitzel, Richard; Seixas, Noah; Olson, John; Daniell, William; Goldman, Bryan

    2004-01-01

    Efforts to characterize nonoccupational noise exposures have focused primarily on infrequent, episodic events. Few studies have assessed noise levels resulting from routine daily activities. In the current study, 112 construction workers wore datalogging noise dosimeters and simultaneously completed activity logs during two phases of data collection. The 81 subjects monitored in phase 1 received logs listing numerous preselected occupational and nonoccupational activities, while the 31 subjects monitored in phase 2 used free-field logs and reported nonoccupational activities in greater detail. Nearly all of the 221 439 1-min intervals of nonoccupational Leq level and activity reporting were below 70 dBA; only a small percentage exceeded 80 dBA. The primary contributor to nonoccupational noise exposure was traveling in a car or bus, while time at home contributed the least. One hundred seventy 24-h Leq levels were computed from the 1-min noise level data. The percentage of phase 2 workday Leq(24) levels which exceeded 80 dBA was higher than that of the nonworkday levels. The mean Leq(24) level of phase 2 workdays was higher than that of nonworkdays, and the difference was statistically significant. Routine nonoccupational noise exposures contributed much less to total noise dose than occupational exposures in the subjects evaluated.

  16. Modifiers of exposure--response estimates for lung cancer among miners exposed to radon progeny

    SciTech Connect

    Hornung, R.W.; Deddens, J.; Roscoe, R. [National Institute for Occupational Safety and Health, Cincinnati, OH (United States)

    1995-03-01

    The association between lung cancer and exposure to radon decay products has been well established. Despite agreement on this point, there is still some degree of uncertainty regarding characteristics of the exposure-response relationship. The use of studies of underground miners to estimate lung cancer risks due to residential radon exposure depends upon a better understanding of factors potentially modifying the exposure-response relationship. Given the diversity in study populations regarding smoking status, mining conditions, risk analysis methodology, and referent populations, the risk estimates across studies are quite similar. However, several factors partially contributing to differences in risk estimates are modified by attained age, time since last exposure, exposure rate, and cigarette smoking patterns. There is growing agreement across studies that relative risk decreases with attained age and time since last exposure. Several studies have also found an inverse exposure-rate effect, i.e., low exposure rates for protracted duration of exposure are more hazardous than equivalent cumulative exposures received at higher rates for shorter periods of time. Additionally, the interaction between radon exposure and cigarette smoking appears to be intermediate between additive and multiplicative in a growing number of studies. Quantitative estimates of these modifying factors are given using a new analysis of data from the latest update of the Colorado Plateau uranium miners cohort. 24 refs., 3 figs., 4 tabs.

  17. DIETARY EXPOSURE AND TOTAL HUMAN EXPOSURE ASSESSMENT:AN OVERVIEW

    EPA Science Inventory

    In this paper I discuss the goals and accomplishments in the dietary research program of USEPA's National Exposure Research Laboratory (NERL). NERL dietary exposure research has the primary goal of establishing measurement methods for dietary ingestion that are consistent with an...

  18. Late Specialization & Early Exposure Late Specialization Early Exposure

    E-print Network

    Yamamoto, Hirosuke

    ) ALESS (Active Learning of English for Science Students) ALESA(Active Learning of English for Students Specialization Early Exposure Early Exposure (1)2012 10 (PEAK: Programs in English at Komaba) 1, 2 (2;23 #12;24 #12;25 PEAK(Programs in English

  19. Historical estimates of external gamma exposure and collective external gamma exposure from testing at the Nevada Test Site. II. Test series after Hardtack II, 1958, and summary

    Microsoft Academic Search

    Lynn R. Anspaugh; Yvonne E. Ricker; Stuart C. Black; R. Frank Grossman; David L. Wheeler; Bruce W. Church; Virgil E. Quinn

    1990-01-01

    The historical data on the cumulative individual external gamma exposures are tabulated for communities around the Nevada Test Site for the time periods of 1961 to the signing of the Limited Test Ban Treaty on 5 August 1963, and from then until 1975. The collective exposures during the two time periods are calculated to be 610 and 320 person-R, respectively.

  20. Occupational exposure to environmental tobacco smoke: results of two personal exposure studies.

    PubMed Central

    Jenkins, R A; Counts, R W

    1999-01-01

    Personal monitoring is a more accurate measure of individual exposure to airborne constituents because it incorporates human activity patterns and collects actual breathing zone samples to which subjects are exposed. Two recent studies conducted by our laboratory offer perspective on occupational exposure to environmental tobacco smoke (ETS) from a personal exposure standpoint. In a study of nearly 1600 workers, levels of ETS were lower than or comparable to those in earlier studies. Limits on smoking in designated areas also acted to reduce overall exposure of workers. In facilities where smoking is permitted, ETS exposures are 10 to 20 times greater than in facilities in which smoking is banned. Service workers were exposed to higher levels of ETS than workers in white-collar occupations. For the narrower occupational category of waiters, waitresses, and bartenders, a second study in one urban location indicated that ETS levels to which wait staff are exposed are not considerably different from those exposure levels of subjects in the larger study who work in environments in which smoking is unrestricted. Bartenders were exposed to higher ETS levels, but there is a distinction between bartenders working in smaller facilities and those working in multiroom restaurant bars, with the former exposed to higher levels of ETS than the latter. In addition, ETS levels encountered by these more highly exposed workers are lower that those estimated by the Occupational Safety and Health Administration. Concomitant area monitoring in the smaller study suggests that area samples can only be used to estimate individual personal exposure to within an order of magnitude or greater. PMID:10350519

  1. Evaluation of cumulative PCB exposure estimated by a job exposure matrix versus PCB serum concentrations.

    PubMed

    Hopf, Nancy B; Ruder, Avima M; Succop, Paul; Waters, Martha A

    2014-05-01

    Although polychlorinated biphenyls (PCBs) have been banned in many countries for more than three decades, exposures to PCBs continue to be of concern due to their long half-lives and carcinogenic effects. In National Institute for Occupational Safety and Health studies, we are using semiquantitative plant-specific job exposure matrices (JEMs) to estimate historical PCB exposures for workers (n?=?24,865) exposed to PCBs from 1938 to 1978 at three capacitor manufacturing plants. A subcohort of these workers (n?=?410) employed in two of these plants had serum PCB concentrations measured at up to four times between 1976 and 1989. Our objectives were to evaluate the strength of association between an individual worker's measured serum PCB levels and the same worker's cumulative exposure estimated through 1977 with the (1) JEM and (2) duration of employment, and to calculate the explained variance the JEM provides for serum PCB levels using (3) simple linear regression. Consistent strong and statistically significant associations were observed between the cumulative exposures estimated with the JEM and serum PCB concentrations for all years. The strength of association between duration of employment and serum PCBs was good for highly chlorinated (Aroclor 1254/HPCB) but not less chlorinated (Aroclor 1242/LPCB) PCBs. In the simple regression models, cumulative occupational exposure estimated using the JEMs explained 14-24% of the variance of the Aroclor 1242/LPCB and 22-39% for Aroclor 1254/HPCB serum concentrations. We regard the cumulative exposure estimated with the JEM as a better estimate of PCB body burdens than serum concentrations quantified as Aroclor 1242/LPCB and Aroclor 1254/HPCB. PMID:23475397

  2. Combined Toxic Exposures and Human Health: Biomarkers of Exposure and Effect

    PubMed Central

    Silins, Ilona; Högberg, Johan

    2011-01-01

    Procedures for risk assessment of chemical mixtures, combined and cumulative exposures are under development, but the scientific database needs considerable expansion. In particular, there is a lack of knowledge on how to monitor effects of complex exposures, and there are few reviews on biomonitoring complex exposures. In this review we summarize articles in which biomonitoring techniques have been developed and used. Most examples describe techniques for biomonitoring effects which may detect early changes induced by many chemical stressors and which have the potential to accelerate data gathering. Some emphasis is put on endocrine disrupters acting via epigenetic mechanisms and on carcinogens. Solid evidence shows that these groups of chemicals can interact and even produce synergistic effects. They may act during sensitive time windows and biomonitoring their effects in epidemiological studies is a challenging task. PMID:21556171

  3. Biomarkers of Secondhand Smoke Exposure in Automobiles

    PubMed Central

    Jones, Ian; St Helen, Gideon; Meyers, Matthew; Dempsey, Delia A.; Havel, Christopher; Jacob, Peyton; Northcross, Amanda; Hammond, S. Katharine; Benowitz, Neal L.

    2013-01-01

    Objectives The objectives of this study were: (1) to characterize the exposure of nonsmokers exposed to secondhand smoke (SHS) in a vehicle using biomarkers, (2) to describe the time-course of the biomarkers over 24 h, and (3) to examine the relationship between tobacco biomarkers and airborne concentrations of SHS markers. Methods Eight nonsmokers were individually exposed to SHS in cars with fully open front windows and closed back windows over an hour from a smoker who smoked 3 cigarettes at 20 min intervals. The nonsmokers sat in the backseat-passenger side, while the smoker sat in the driver’s seat. Plasma cotinine and urine cotinine, 3-hydroxycotinine (3HC), and 4-(methylnitrosoamino)-(3-pyridyl)-1-butanol (NNAL) were compared in samples taken at baseline and several time-points after exposure. Nicotine, particulate matter (PM2.5), and carbon monoxide (CO) were measured inside and outside the vehicle and ventilation rates in the cars were measured. Results Average plasma cotinine and the molar sum of urine cotinine and 3HC (COT+3HC) increased 4-fold, urine cotinine increased 6-fold, and urine NNAL increased ~27 times compared to baseline biomarker levels. Plasma cotinine, urine COT+3HC and NNAL peaked at 4–8 hours post-exposure while urine cotinine peaked within 4 hours. Plasma cotinine was significantly correlated to PM2.5 (Spearman correlation (rs = 0.94) and CO (rs = 0.76) but not to air nicotine. The correlations between urine biomarkers, cotinine, COT+3HC, and NNAL and air nicotine, PM2.5, and CO were moderate but non-significant (rs range, 0.31 – 0.60). Conclusion Brief SHS exposure in cars resulted in substantial increases in levels of tobacco biomarkers in nonsmokers. For optimal characterization of SHS exposure, tobacco biomarkers should be measured within 4–8 h post-exposure. Additional studies are needed to better describe the relationship between tobacco biomarkers and environmental markers of SHS. PMID:23349229

  4. EFFECTS OF TRITIUM GAS EXPOSURE ON EPDM ELASTOMER

    SciTech Connect

    Clark, E.

    2009-12-11

    Samples of four formulations of ethylene-propylene diene monomer (EPDM) elastomer were exposed to initially pure tritium gas at one atmosphere and ambient temperature for various times up to about 420 days in closed containers. Two formulations were carbon-black-filled commercial formulations, and two were the equivalent formulations without filler synthesized for this work. Tritium effects on the samples were characterized by measuring the sample volume, mass, flexibility, and dynamic mechanical properties and by noting changes in appearance. The glass transition temperature was determined by analysis of the dynamic mechanical properties. The glass transition temperature increased significantly with tritium exposure, and the unfilled formulations ceased to behave as elastomers after the longest tritium exposure. The filled formulations were more resistant to tritium exposure. Tritium exposure made all samples significantly stiffer and therefore much less able to form a reliable seal when employed as O-rings. No consistent change of volume or density was observed; there was a systematic lowering of sample mass with tritium exposure. In addition, the significant radiolytic production of gas, mainly protium (H{sub 2}) and HT, by the samples when exposed to tritium was characterized by measuring total pressure in the container at the end of each exposure and by mass spectroscopy of a gas sample at the end of each exposure. The total pressure in the containers more than doubled after {approx}420 days tritium exposure.

  5. Acute high dose exposure to benzene in shipyard workers.

    PubMed

    Midzenski, M A; McDiarmid, M A; Rothman, N; Kolodner, K

    1992-01-01

    Fifteen degassers were acutely exposed over several days to high concentrations (> 60 ppm) of benzene during removal of residual fuel (degassing) from shipboard fuel tanks. Medical surveillance evaluation mandated by the Occupational Safety and Health Administration's (OSHA) Benzene Standard initially revealed 11 workers (73%) reporting neurotoxic symptoms while degassing. Workers with more than 2 days (16 hours) of acute exposure were significantly more likely to report dizziness and nausea than those with 2 or fewer days of acute exposure. Repeated laboratory analyses performed over a 4-month period after the acute exposure revealed at least one hematologic abnormality consistent with benzene exposure in 9 (60%) of these degassers. One year later, 6 workers (40%) had persistent abnormalities; an additional worker with normal hematologic parameters at the time of our initial evaluation subsequently developed an abnormality consistent with benzene exposure. Numerous large granular lymphocytes were observed on 6 (40%) of the peripheral blood smears. Despite these laboratory findings, there were no significant associations between the presence of hematologic abnormalities and either the number of hours of acute benzene exposure or the duration of employment as a degasser. Volatilization of benzene from the residual fuel was the suspected source of benzene in the headspace of tanks. Confined space exposure to petroleum products may be exposing workers to benzene at levels above the OSHA Short-Term Exposure Limit (STEL). This situation warrants further study. PMID:1442788

  6. The impacts of repeated cold exposure on insects.

    PubMed

    Marshall, Katie E; Sinclair, Brent J

    2012-05-15

    Insects experience repeated cold exposure (RCE) on multiple time scales in natural environments, yet the majority of studies of the effects of cold on insects involve only a single exposure. Three broad groups of experimental designs have been employed to examine the effects of RCE on insect physiology and fitness, defined by the control treatments: 'RCE vs cold', which compares RCE with constant cold conditions; 'RCE vs warm', which compares RCE with constant warm conditions; and 'RCE vs matched cold' which compares RCE with a prolonged period of cold matched by time to the RCE condition. RCE are generally beneficial to immediate survival, and increase cold hardiness relative to insects receiving a single prolonged cold exposure. However, the effects of RCE depend on the study design, and RCE vs warm studies cannot differentiate between the effects of cold exposure in general vs RCE in particular. Recent studies of gene transcription, immune function, feeding and reproductive output show that the responses of insects to RCE are distinct from the responses to single cold exposures. We suggest that future research should attempt to elucidate the mechanistic link between physiological responses and fitness parameters. We also recommend that future RCE experiments match the time spent at the stressful low temperature in all experimental groups, include age controls where appropriate, incorporate a pilot study to determine time and intensity of exposure, and measure sub-lethal impacts on fitness. PMID:22539727

  7. Prolonged exposure to the candidate microbicide C31G differentially reduces cellular sensitivity to agent re-exposure.

    PubMed

    Catalone, Bradley J; Ferguson, Mary Lee; Miller, Shendra R; Malamud, Dan; Kish-Catalone, Tina; Thakkar, Nina J; Krebs, Fred C; Howett, Mary K; Wigdahl, Brian

    2005-09-01

    Comparative assays of in vitro cytotoxicity using nonoxynol-9 (N-9) and the candidate microbicides C31G and sodium dodecyl sulfate (SDS) demonstrated that these agents, which are, respectively, characterized as nonionic, amphoteric, and anionic surfactants, differed in their concentration-dependent effects on cell viability, especially after prolonged exposure. We hypothesized that differences in cellular sensitivity may have been due, in part, to cellular changes induced by long-term exposure to each agent. To examine this possibility, HeLa cells were exposed to N-9, C31G, or SDS for extended periods of time and subsequently reassessed for sensitivity to each of these agents. Following 10 continuous days of C31G exposure, HeLa cells were less sensitive to a subsequent C31G exposure compared to cells that had not undergone long-term C31G treatment. Interestingly, long-term C31G exposure also changed subsequent sensitivity to N-9 but not SDS. In contrast, prolonged exposure to either N-9 or SDS did not reduce sensitivity to re-exposure. The effect of long-term C31G exposure was both concentration-dependent and transient, as treated cells reverted to pre-exposure sensitivity in a time-dependent manner following the cessation of C31G exposure. Lipid analyses of cells exposed to C31G for extended durations revealed altered phospholipid profiles relative to C31G-naïve cells. Experiments examining the individual components of C31G demonstrated the involvement of the amine oxide moiety in reductions in cellular sensitivity. These studies, which provide new information concerning the cytotoxicity of surfactant microbicides, suggest that cervicovaginal epithelial cells may have greater in vivo tolerance for products containing C31G through unique interactions between C31G and components of the cellular membranes. PMID:16154719

  8. Development and application of a model (ExDoM) for calculating the respiratory tract dose and retention of particles under variable exposure conditions

    Microsoft Academic Search

    Victoria Aleksandropoulou; Mihalis Lazaridis

    The ExDoM is a model for calculating the human exposure and the deposition, dose, clearance, and finally retention of aerosol\\u000a particles in the respiratory tract at specific times during and after exposure, under variable exposure conditions. Specifically,\\u000a the model incorporates an exposure module which allows the user to set variable or static exposure conditions (exposure concentration,\\u000a physical exertion levels, and

  9. Short term exposure to cooking fumes and pulmonary function

    PubMed Central

    Svedahl, Sindre; Svendsen, Kristin; Qvenild, Torgunn; Sjaastad, Ann Kristin; Hilt, Bjørn

    2009-01-01

    Background Exposure to cooking fumes may have different deleterious effects on the respiratory system. The aim of this study was to look at possible effects from inhalation of cooking fumes on pulmonary function. Methods Two groups of 12 healthy volunteers (A and B) stayed in a model kitchen for two and four hours respectively, and were monitored with spirometry four times during twenty four hours, on one occasion without any exposure, and on another with exposure to controlled levels of cooking fumes. Results The change in spirometric values during the day with exposure to cooking fumes, were not statistically significantly different from the changes during the day without exposure, with the exception of forced expiratory time (FET). The change in FET from entering the kitchen until six hours later, was significantly prolonged between the exposed and the unexposed day with a 15.7% increase on the exposed day, compared to a 3.2% decrease during the unexposed day (p-value = 0.03). The same tendency could be seen for FET measurements done immediately after the exposure and on the next morning, but this was not statistically significant. Conclusion In our experimental setting, there seems to be minor short term spirometric effects, mainly affecting FET, from short term exposure to cooking fumes. PMID:19409114

  10. DCEG Research on Formaldehyde Exposure

    Cancer.gov

    Studies to investigate occupational formaldehyde exposure and cancer risk, including an industrial cohort study of over 25,000 workers, a case-control study of workers in the funeral industry, and a cross-sectional study to quantify leukemia-specific chromosome changes associated with formaldehyde exposure

  11. Human exposure to ultraviolet radiation

    SciTech Connect

    Passchier, W.F. (Health Council of the Netherlands, The Hague (NL)); Bosnjakovic, B.F.M. (Ministry of Housing, The Hague (NL))

    1987-01-01

    These proceedings contain over 50 selections. Some of the title are: Man and ultraviolet radiation; Effects of ultraviolet radiations on the human skin: emphasis on skin cancer; Human exposure to ultraviolet radiation: Quantitative modelling of skin cancer incidence; Human exposure to ultraviolet radiation: Data; and Share of erythema dose of solar radiation in high mountains.

  12. NATIONAL OCCUPATIONAL EXPOSURE SURVEY (NOES)

    EPA Science Inventory

    From 1981 to 1983, NIOSH conducted the National Occupational Exposure Survey (NOES) that collected data on potential occupational exposures to chemical, physical, and biological agents. The survey involved on-site visits to 4,490 establishments in 522 industry types [OMB 1972] em...

  13. Mercury exposure and children's health.

    PubMed

    Bose-O'Reilly, Stephan; McCarty, Kathleen M; Steckling, Nadine; Lettmeier, Beate

    2010-09-01

    Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic (methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children's health. PMID:20816346

  14. DETERMINANTS OF RESIDENTIAL LEAD EXPOSURE

    EPA Science Inventory

    The phase-out of leaded gasoline, and the accompanying decrease in lead emissions, resulted in a dramatic decline in mean blood lead levels from the late 1970s through the early 1990s. Nonetheless, lead exposures remain a public health concern. Long-term exposures to even low...

  15. Quantifying light exposure patterns in young adult students.

    PubMed

    Alvarez, Amanda A; Wildsoet, Christine F

    2013-10-01

    Exposure to bright light appears to be protective against myopia in both animals (chicks, monkeys) and children, but quantitative data on human light exposure are limited. In this study, we report on a technique for quantifying light exposure using wearable sensors. Twenty-seven young adult subjects wore a light sensor continuously for two weeks during one of three seasons, and also completed questionnaires about their visual activities. Light data were analyzed with respect to refractive error and season, and the objective sensor data were compared with subjects' estimates of time spent indoors and outdoors. Subjects' estimates of time spent indoors and outdoors were in poor agreement with durations reported by the sensor data. The results of questionnaire-based studies of light exposure should thus be interpreted with caution. The role of light in refractive error development should be investigated using multiple methods such as sensors to complement questionnaires. PMID:25342873

  16. Quantifying light exposure patterns in young adult students

    PubMed Central

    Alvarez, Amanda A.; Wildsoet, Christine F.

    2014-01-01

    Exposure to bright light appears to be protective against myopia in both animals (chicks, monkeys) and children, but quantitative data on human light exposure are limited. In this study, we report on a technique for quantifying light exposure using wearable sensors. Twenty-seven young adult subjects wore a light sensor continuously for two weeks during one of three seasons, and also completed questionnaires about their visual activities. Light data were analyzed with respect to refractive error and season, and the objective sensor data were compared with subjects’ estimates of time spent indoors and outdoors. Subjects’ estimates of time spent indoors and outdoors were in poor agreement with durations reported by the sensor data. The results of questionnaire-based studies of light exposure should thus be interpreted with caution. The role of light in refractive error development should be investigated using multiple methods such as sensors to complement questionnaires. PMID:25342873

  17. Subliminal mere exposure and explicit and implicit positive affective responses.

    PubMed

    Hicks, Joshua A; King, Laura A

    2011-06-01

    Research suggests that repeated subliminal exposure to environmental stimuli enhances positive affective responses. To date, this research has primarily concentrated on the effects of repeated exposure on explicit measures of positive affect (PA). However, recent research suggests that repeated subliminal presentations may increase implicit PA as well. The present study tested this hypothesis. Participants were either subliminally primed with repeated presentations of the same stimuli or only exposed to each stimulus one time. Results confirmed predictions showing that repeated exposure to the same stimuli increased both explicit and implicit PA. Implications for the role of explicit and implicit PA in attitudinal judgements are discussed. PMID:21547773

  18. Community sensitivity to changes in aircraft noise exposure

    NASA Technical Reports Server (NTRS)

    Fidell, S.; Horonjeff, R.; Teffeteller, S.; Pearsons, K.

    1981-01-01

    Interviews were conducted in the vicinity of Burbank Airport during a four month period during which a counterbalanced series of changes in aircraft noise exposure occurred due to runway repairs. Another interview was undertaken approximately one year after completion of the initial runway repairs. Noise measurements were made in conjunction with administration of a brief questionnaire to a near exhaustive sample of residents in four airport neighborhoods. The magnitude and direction of change of annoyance with aircraft noise exposure corresponded closely to the actual changes in physical exposure. Estimates were made of time constants for the rate of change of attitudes toward aircraft noise.

  19. Rockfall exposures in Montserrat mountain

    NASA Astrophysics Data System (ADS)

    Fontquerni Gorchs, Sara; Vilaplana Fernández, Joan Manuel; Guinau Sellés, Marta; Jesús Royán Cordero, Manuel

    2015-04-01

    This study shows the developed methodology to analyze the exposure level on a 1:25000 scale, and the results obtained by applying it to an important part of the Monataña de Montserrat Natural Park for vehicles with and without considering their occupants. The development of this proposal is part of an ongoing study which focuses more in-depth in the analysis of the rockfall risk exposure in different scales and in different natural and social contexts. This research project applies a methodology to evaluate the rockfall exposure level based on the product of the frequency of occurrence of the event by an exposure function of the vulnerable level on a 1:25,000 scale although the scale used for the study was 1:10,000. The proposed methodology to calculate the exposure level is based on six phases: 1- Identification, classification and inventory of every element potentially under risk. 2- Zoning of the frequency of occurrence of the event in the studied area. 3- Design of the exposure function for each studied element. 4- Obtaining the Exposure index, it can be defined as the product of the frequency of occurrence by the exposure function of the vulnerable element through SIG analysis obtained with ArcGis software (ESRI) 5- Obtaining exposure level by grouping into categories the numerical values of the exposure index. 6- Production of the exposition zoning map. The different types of vulnerable elements considered in the totality of the study are: Vehicles in motion, people in vehicles in motion, people on paths, permanent elements and people in buildings. Each defined typology contains all elements with same characteristics and an exposure function has been designed for each of them. For the exposure calculation, two groups of elements have been considered; firstly the group of elements with no people involved and afterwards same group of elements but with people involved. This is a first comprehensive and synthetic work about rockfall exposure on the Montserrat Mountain. It is important to mention that the exposure level calculation has been obtained from natural hazard data do not protected by defense works. Results of this work enable us to consider best strategies to reduce rockfalls risk in the PNMM. It is clear that, apart from the required structural defense works, some of them already made, implementation of strategies not involving structural defense is, in the medium and long term, the best policy to mitigate the risk. In the PNMM case, rethinking of mobility and traffic management on the mountain access would be definitely helpful to achieve a minimized geological risk.

  20. Chemical exposure and intestinal function.

    PubMed Central

    Schiller, C M

    1979-01-01

    The particular substances that are ingested by individuals are the consequence of their environmental, residential, and occupational exposures. The possible effects of these exposures on intestinal functions can be examined by the evaluation of in vivo or in vitro exposure followed by an in vivo and/or in vitro monitoring of effects. Several examples of the in vivo exposure and in vitro monitoring approach are presented to demonstrate the consequences of oral exposure to either a heavy metal (arsenic), or a herbicide contaminant (2,3,7,8-tetrachlorodibenzo-p-dioxin) or a jet fuel propellant (hydrazine) and the subsequent measurement of either a particular metabolic pathway, or a cell-specific enzyme induction or the development of brush border enzymes are presented. Images FIGURE 6. FIGURE 7. FIGURE 8. a FIGURE 8. b FIGURE 9. PMID:120255

  1. Occupational exposures estimated by means of job exposure matrices in relation to lung function in the PAARC survey.

    PubMed Central

    Le Moual, N; Orlowski, E; Schenker, M B; Avignon, M; Brochard, P; Kauffmann, F

    1995-01-01

    OBJECTIVES--The aim of this analysis of the French Cooperative PAARC (Pollution Atmosphérique et Affections Respiratoires Chroniques) survey, was to test whether occupational exposures to dusts, gases, or chemical fumes or to specific hazards, estimated by job exposure matrices, were related to a decrease in forced expiratory volume in one second (FEV1). METHODS--The most recent occupation was recorded in adults, aged 25-59, from non-manual worker households. Analysis was restricted to 10,046 subjects whose occupation was encountered at least 10 times in the study and who performed good FEV1 tracings. From occupational title, exposures to dusts, gases, and chemical fumes, and to specific hazards were classified in three categories (no, low, and high) with a British, a French, and an Italian job exposure matrix. Specific hazards were analysed for the British and French job exposure matrices for the same 42 specific dusts, gases, and chemical fumes. To limit spurious associations, a selection of seven hazard groups and 12 specific hazards was set before the start of the analysis. Based on the consistency of the relations according to sex and the British and French job exposure matrices, associations of age, height, city, and smoking adjusted FEV1 score with occupational exposures were classified as very likely, possible, or unlikely. RESULTS--For the three job exposure matrices and both sexes clear exposure-response relations between the level of exposure to dusts, gases, and chemical fumes, and a decrease in FEV1 were found. Associations with FEV1 were classified as very likely for known hazards such as organic dusts and textile dusts, and not previously recognised hazards such as polycyclic aromatic hydrocarbons (PAHs) and detergents, and as possible for solvents, waxes and polishes, and diesel fumes. Associations found for PAHs and solvents were confirmed by the Italian job exposure matrix. Associations remained significant in women, but not in men, after adjustment for educational level. CONCLUSIONS--Hypotheses have been generated for exposure to detergents, PAHs, and solvents, but they need to be interpreted with caution before replication. Significant associations found for known risk factors with a decrease in FEV1 are arguments for the validity of the matrices. Despite the expected limitations of job exposure matrices, these results encourage further work to improve exposure assessment by job exposure matrices. PMID:7489052

  2. Asbestos exposure indices

    SciTech Connect

    Lippmann, M.

    1988-06-01

    The ability of inhaled asbestos to produce asbestosis, lung cancer, and mesothelioma in both humans and animals is well established, and asbestos exposures in the occupational and general community environment are recognized as significant hazards. However, it has not been possible to establish realistic and credible dose-response relationships, primarily because of the authors inability to define which constituents of the aerosols produce or initiate the pathological responses. It is generally acknowledged that the responses are associated with the fibers rather than the nonfibrous silicate mineral of the same chemical composition. Available data from experimental studies experimental studies in animals exposed by injection and inhalation to fibers of defined size distributions are reviewed, along with data from studies of fiber distributions in lungs of exposed humans in relation to the effects associated with the retained fibers. It is concluded that asbestosis is most closely related to the surface area of retained fibers, that mesothelioma is most closely associated with numbers of fibers longer than approx. 5 ..mu..m and thinner than approx. 0.1 ..mu..m, and that lung cancer is most closely associated with fibers longer than approx. 10 ..mu..m and thicker than approx. 0.15 ..mu..m. The implications of these conclusions on methods for fiber sampling and analyses are discussed.

  3. Accidental radiation exposure and azoospermia.

    PubMed

    Bezold, G; Gottlöber, P; Gall, H; Peter, R U

    2000-01-01

    Seven Georgian male soldiers (19-25 years old) had accidentally been exposed to radiation by Cs-137 between April 1996 and May 1997. No information about the exact time and duration of exposure was available. All patients presented with the subacute stage of Cutaneous Radiation Syndrome with deep painful ulcers on different body sites, predominantly on the legs. Semen analyses showed complete azoospermia in 4 patients, with elevated follicle-stimulating hormone (FSH) in 3 and elevated luteinizing hormone (LH) in 2 of them. One patient had severe oligozoospermia of 7 million sperm per mL, with normal sperm motility and morphology; his FSH and LH levels were elevated. One patient had complete normozoospermia, and the seventh patient had polyzoospermia of 340 million per mL; both of these patients had normal serum hormone levels. Only the patient with oligozoospermia reported a history of delayed testicular descent; his physical examination showed relatively soft and small testicles and a varicocele with considerable reflux. The physical andrological examinations were normal in the other 6 patients. It is very likely that the azoospermia in the 4 patients can be attributed to the radiation accident. In conclusion, it is essential to perform andrological examinations in patients who have been exposed to radiation even if there are only cutaneous injuries detectable, as a high percentage of them can show azoospermia. PMID:10819447

  4. OSHA's permissible exposure limits: Regulatory compliance versus health risk

    Microsoft Academic Search

    Robert C. Spear; Steve Selvin

    1989-01-01

    Workplace exposures to airborne chemicals are regulated in the U.S. by the Occupational Safety and Health Administration (OSHA) via the promulgation of permissible exposure limits (PELs). These limits, usually defined as eight-hour time-weighted average values, are enforced as concentrations never to be exceeded. In the case of chronic or delayed toxicants, the PEL is determined from epidemiological evidence and\\/or quantitative

  5. Assessing radiation exposure during endoscopic-guided percutaneous nephrolithotomy

    PubMed Central

    Lantz, Andrea G.; O’Malley, Padraic; Ordon, Michael; Lee, Jason Y.

    2014-01-01

    Introduction: Percutaneous nephrolithotomy (PCNL) may be associated with significant ionizing radiation exposure for patients and operating room staff. Endoscopic-guided PCNL (ePCNL) is a technique that may be associated with less radiation exposure. This study examines ePCNL-related radiation exposure (fluoroscopy time, effective dose) and investigates variables that may predict increased exposure. Methods: A retrospective review of all consecutive ePCNLs performed at our institution, by a single surgeon, was conducted between November 2011 and November 2013. Patient demographics, stone characteristics and perioperative details were recorded, including radiation exposure. Pearson and Spearman correlation were used to assess variables correlated with radiation exposure. Results: In total, 55 ePCNL cases were included in the study. The mean age was 60 ± 15 years, mean body mass index (BMI) 30.0 ± 6.4 kg/m2 and mean stone size 3.2 × 2.1 cm. Seven cases (13%) involved complete staghorn stones, and 69% involved supracostal punctures. The mean fluoroscopy time was 3.4 ± 2.3 minutes, mean ED 2.4 ± 1.9 mSv. The treatment success rate, assessed 1-week postoperatively, was 87.3% and 7.3% of cases required ancillary procedures. The overall complication rate was 29%, but only 3 cases (5.5%) were Clavien ?3. Longer fluoroscopy time correlated with increased stone size (p < 0.01), longer operative time (p < 0.01) and lower treatment success rates (p < 0.01); higher effective dose correlated with longer fluoroscopy time (p < 0.01) and increased skin-to-stone distance (p < 0.01). BMI did not correlate with fluoroscopy time or effective dose. Conclusions: Outcomes of ePCNL are comparable to traditional PCNL techniques and may be associated with lower radiation exposure, particularly beneficial for patients with higher BMI. PMID:25408802

  6. EUV mask particle adders during scanner exposure

    NASA Astrophysics Data System (ADS)

    Hyun, Yoonsuk; Kim, Jinsoo; Kim, Kyuyoung; Koo, Sunyoung; Kim, SeoMin; Kim, Youngsik; Lim, Changmoon; Kwak, Nohjung

    2015-03-01

    As EUV reaches high volume manufacturing, scanner source power and reticle defectivity attract a lot of attention. Keeping a EUV mask clean after mask production is as essential as producing a clean EUV mask. Even though EUV pellicle is actively investigated, we might expose EUV masks without EUV pellicle for some time. To keep clean EUV mask under pellicle-less lithography, EUV scanner cleanliness needs to meet the requirement of high volume manufacturing. In this paper, we will show the cleanliness of EUV scanners in view of mask particle adders during scanner exposure. From this we will find several tendencies of mask particle adders depending on mask environment in scanner. Further we can categorize mask particle adders, which could show the possible causes of particle adders during exposure in scanners.

  7. Radiographic detection of initial carious lesions on the proximal surfaces of teeth. Part I. The influence of exposure conditions

    SciTech Connect

    Arnold, L.V.

    1987-08-01

    The relationship between a number of technical exposure conditions and the diagnostic value of bitewing radiographs in the interpretation of initial proximal carious lesions was evaluated. The most important exposure factors for radiographs are tube voltage, filtration, and exposure time. Tube voltage and filtration were found to have an insignificant influence on the diagnostic quality. Exposure time proved to be the most critical factor in influencing diagnostic quality. The greatest difference in diagnostic quality, however, was caused by differences between observers.

  8. Fetal Alcohol Exposure

    MedlinePLUS

    ... feeding, bathing, counting money, telling time, and minding personal safety FASD-related brain damage makes it difficult to ... including training in social skills, problem solving, and personal safety. 10 For more information, please visit: www.niaaa. ...

  9. Inhalation and dermal exposure among asphalt paving workers.

    PubMed

    McClean, M D; Rinehart, R D; Ngo, L; Eisen, E A; Kelsey, K T; Herrick, R F

    2004-11-01

    The primary objective of this study was to identify determinants of inhalation and dermal exposure to polycyclic aromatic compounds (PACs) among asphalt paving workers. The study population included three groups of highway construction workers: 20 asphalt paving workers, as well as 12 millers and 6 roadside construction workers who did not work with hot-mix asphalt. During multiple consecutive work shifts, personal air samples were collected from each worker's breathing zone using a Teflon filter and cassette holder connected in series with an XAD-2 sorbent tube, while dermal patch samples were collected from the underside of each worker's wrist. All exposure samples were analyzed for PACs, pyrene and benzo[a]pyrene. Inhalation and dermal PAC exposures were highest among asphalt paving workers. Among paving workers, inhalation and dermal PAC exposures varied significantly by task, crew, recycled asphalt product (RAP) and work rate (inhalation only). Asphalt mix containing high RAP was associated with a 5-fold increase in inhalation PAC exposures and a 2-fold increase in dermal PAC exposure, compared with low RAP mix. The inhalation PAC exposures were consistent with the workers' proximity to the primary source of asphalt fume (paver operators > screedmen > rakers > roller operators), such that the adjusted mean exposures among paver operators (5.0 microg/m3, low RAP; 24 microg/m3, high RAP) were 12 times higher than among roller operators (0.4 microg/m3, low RAP; 2.0 microg/m3, high RAP). The dermal PAC exposures were consistent with the degree to which the workers have actual contact with asphalt-contaminated surfaces (rakers > screedmen > paver operators > roller operators), such that the adjusted mean exposures among rakers (175 ng/cm2, low RAP; 417 ng/cm2, high RAP) were approximately 6 times higher than among roller operators (27 ng/cm2, low RAP; 65 ng/cm2, high RAP). Paving task, RAP content and crew were also found to be significant determinants of inhalation and dermal exposure to pyrene. The effect of RAP content, as well as the fact that exposures were higher among paving workers than among millers and roadside construction workers, suggests that the PAC and pyrene exposures experienced by these paving workers were asphalt-related. PMID:15509633

  10. A global compilation of glacial 10Be and 26Al exposure ages

    NASA Astrophysics Data System (ADS)

    Heyman, Jakob

    2015-04-01

    Cosmogenic dating has enabled direct dating of glacial landforms and deposits, greatly improving our understanding of past glaciations in terms of timing as well as glacial erosion and preservation. Over the last 25 years a large (and growing) number of publications have reported cosmogenic exposure ages from glacial landforms around the world. Here a global compilation of glacial 10Be and 26Al exposure ages will be presented aiming at an analysis and quantification of cosmogenic dating uncertainties. The dataset consists of >9300 10Be exposure ages and >1400 26Al exposure ages with full input data (location, elevation, sample type, sample thickness, concentration, standardization etc.). All exposure ages have been recalculated with updated reference production rates and organized in discrete glacial landform groups enabling evaluation of exposure age scatter due to prior and incomplete exposure. Exposure age scatter is common and increase significantly for glacial landforms older than the global last glacial maximum, making precise cosmogenic dating of older glaciations difficult. The data will be used to evaluate exposure dating of different sample types (boulder vs bedrock surfaces) and sample selection based on boulder size. Exposure ages from the paleo-ice sheets will be compared with mountain glacier exposure ages, aiming at picking out the good (well-clustered) exposure ages. The full dataset will eventually be posted online and continuously updated with published exposure age data.

  11. CHILDREN'S EXPOSURE ASSESSMENT: A REVIEW OF FACTORS INFLUENCING CHILDREN'S EXPOSURE AND THE DATA AVAILABLE TO CHARACTERIZE AND ASSESS THAT EXPOSURE

    EPA Science Inventory

    We review the factors influencing children's exposure to environmental contaminants and the data available to characterize and assess that exposure. Children's activity pattern data requirements are demonstrated in the context of the algorithms used to estimate exposure by inha...

  12. Bisphenol A Exposure Disrupts Genomic Imprinting in the Mouse

    PubMed Central

    Susiarjo, Martha; Sasson, Isaac; Mesaros, Clementina; Bartolomei, Marisa S.

    2013-01-01

    Exposure to endocrine disruptors is associated with developmental defects. One compound of concern, to which humans are widely exposed, is bisphenol A (BPA). In model organisms, BPA exposure is linked to metabolic disorders, infertility, cancer, and behavior anomalies. Recently, BPA exposure has been linked to DNA methylation changes, indicating that epigenetic mechanisms may be relevant. We investigated effects of exposure on genomic imprinting in the mouse as imprinted genes are regulated by differential DNA methylation and aberrant imprinting disrupts fetal, placental, and postnatal development. Through allele-specific and quantitative real-time PCR analysis, we demonstrated that maternal BPA exposure during late stages of oocyte development and early stages of embryonic development significantly disrupted imprinted gene expression in embryonic day (E) 9.5 and 12.5 embryos and placentas. The affected genes included Snrpn, Ube3a, Igf2, Kcnq1ot1, Cdkn1c, and Ascl2; mutations and aberrant regulation of these genes are associated with imprinting disorders in humans. Furthermore, the majority of affected genes were expressed abnormally in the placenta. DNA methylation studies showed that BPA exposure significantly altered the methylation levels of differentially methylated regions (DMRs) including the Snrpn imprinting control region (ICR) and Igf2 DMR1. Moreover, exposure significantly reduced genome-wide methylation levels in the placenta, but not the embryo. Histological and immunohistochemical examinations revealed that these epigenetic defects were associated with abnormal placental development. In contrast to this early exposure paradigm, exposure outside of the epigenetic reprogramming window did not cause significant imprinting perturbations. Our data suggest that early exposure to common environmental compounds has the potential to disrupt fetal and postnatal health through epigenetic changes in the embryo and abnormal development of the placenta. PMID:23593014

  13. Noise exposure and hearing loss among sand and gravel miners.

    PubMed

    Landen, Deborah; Wilkins, Steve; Stephenson, Mark; McWilliams, Linda

    2004-08-01

    The objectives of this study were to describe workplace noise exposures, risk factors for hearing loss, and hearing levels among sand and gravel miners, and to determine whether full shift noise exposures resulted in changes in hearing thresholds from baseline values. Sand and gravel miners (n = 317) were interviewed regarding medical history, leisure-time and occupational noise exposure, other occupational exposures, and use of hearing protection. Audiometric tests were performed both before the work shift (following a 12-hour noise-free interval) and immediately following the work shift. Full shift noise dosimetry was conducted. Miners' noise exposures exceeded the Recommended Exposure Limit (REL) of the National Institute for Occupational Safety and Health (NIOSH) for 69% of workers, and exceeded the Mine Safety and Health Administration's action level for enrollment in a hearing conservation program for 41% of workers. Significantly higher noise exposures occurred among employees of small companies, among workers with a job classification of truck driver, among males, and among black workers. Hearing protection usage was low, with 48% of subjects reporting that they never used hearing protection. Hearing impairment, as defined by NIOSH, was present among 37% of 275 subjects with valid audiograms. Black male workers and white male workers had higher hearing thresholds than males from a comparison North Carolina population unexposed to industrial noise. Small but statistically significant changes in hearing thresholds occurred following full shift noise exposure among subjects who had good hearing sensitivity at baseline. In a logistic regression model, age and history of a past noisy job were significant predictors of hearing impairment. Overall, sand and gravel workers have excessive noise exposures and significant hearing loss, and demonstrate inadequate use of hearing protection. Well-designed hearing conservation programs, with reduction of noise exposure, are clearly needed. PMID:15238306

  14. Parental Smoking Exposure and Adolescent Smoking Trajectories

    PubMed Central

    Gilman, Stephen E.; Rende, Richard; Luta, George; Tercyak, Kenneth P.; Niaura, Raymond S.

    2014-01-01

    OBJECTIVE: In a multigenerational study of smoking risk, the objective was to investigate the intergenerational transmission of smoking by examining if exposure to parental smoking and nicotine dependence predicts prospective smoking trajectories among adolescent offspring. METHODS: Adolescents (n = 406) ages 12 to 17 and a parent completed baseline interviews (2001–2004), and adolescents completed up to 2 follow-up interviews 1 and 5 years later. Baseline interviews gathered detailed information on parental smoking history, including timing and duration, current smoking, and nicotine dependence. Adolescent smoking and nicotine dependence were assessed at each time point. Latent Class Growth Analysis identified prospective smoking trajectory classes from adolescence into young adulthood. Logistic regression was used to examine relationships between parental smoking and adolescent smoking trajectories. RESULTS: Four adolescent smoking trajectory classes were identified: early regular smokers (6%), early experimenters (23%), late experimenters (41%), and nonsmokers (30%). Adolescents with parents who were nicotine-dependent smokers at baseline were more likely to be early regular smokers (odds ratio 1.18, 95% confidence interval 1.05–1.33) and early experimenters (odds ratio 1.04, 95% confidence interval 1.04–1.25) with each additional year of previous exposure to parental smoking. Parents’ current non-nicotine–dependent and former smoking were not associated with adolescent smoking trajectories. CONCLUSIONS: Exposure to parental nicotine dependence is a critical factor influencing intergenerational transmission of smoking. Adolescents with nicotine-dependent parents are susceptible to more intense smoking patterns and this risk increases with longer duration of exposure. Research is needed to optimize interventions to help nicotine-dependent parents quit smoking early in their children’s lifetime to reduce these risks. PMID:24819567

  15. Adolescent alcohol exposure: Are there separable vulnerable periods within adolescence?

    PubMed

    Spear, Linda Patia

    2015-09-01

    There are two key alcohol use patterns among human adolescents that confer increased vulnerability for later alcohol abuse/dependence, along with neurocognitive alterations: (a) early initiation of use during adolescence, and (b) high rates of binge drinking that are particularly prevalent late in adolescence. The central thesis of this review is that lasting neurobehavioral outcomes of these two adolescent exposure patterns may differ. Although it is difficult to disentangle consequences of early use from later binge drinking in human studies given the substantial overlap between groups, these two types of problematic adolescent use are differentially heritable and hence separable to some extent. Although few studies using animal models have manipulated alcohol exposure age, those studies that have have typically observed timing-specific exposure effects, with more marked (or at least different patterns of) lasting consequences evident after exposures during early-mid adolescence than late-adolescence/emerging adulthood, and effects often restricted to male rats in those few instances where sex differences have been explored. As one example, adult male rats exposed to ethanol during early-mid adolescence (postnatal days [P] 25-45) were found to be socially anxious and to retain adolescent-typical ethanol-induced social facilitation into adulthood, effects that were not evident after exposure during late-adolescence/emerging adulthood (P45-65); exposure at the later interval, however, induced lasting tolerance to ethanol's social inhibitory effects that was not evident after exposure early in adolescence. Females, in contrast, were little influenced by ethanol exposure at either interval. Exposure timing effects have likewise been reported following social isolation as well as after repeated exposure to other drugs such as nicotine (and cannabinoids), with effects often, although not always, more pronounced in males where studied. Consistent with these timing-specific exposure effects, notable maturational changes in brain have been observed from early to late adolescence that could provide differential neural substrates for exposure timing-related consequences, with for instance exposure during early adolescence perhaps more likely to impact later self-administration and social/affective behaviors, whereas exposures later in adolescence may be more likely to influence cognitive tasks whose neural substrates (such as the prefrontal cortex [PFC]) are still undergoing maturation at that time. More work is needed, however to characterize timing-specific effects of adolescent ethanol exposures and their sex dependency, determine their neural substrates, and assess their comparability to and interactions with adolescent exposure to other drugs and stressors. Such information could prove critical for informing intervention/prevention strategies regarding the potential efficacy of efforts directed toward delaying onset of alcohol use versus toward reducing high levels of use and risks associated with that use later in adolescence. PMID:25624108

  16. Cosmogenic 3 He surface-exposure dating of stone pavements

    E-print Network

    Ahmad, Sajjad

    geologic time scales and to test this new model. These exposure ages are stratigraphically consistent, show at the land surface in a time-transgressive manner. A newly proposed model for pavement evolution differs from at the surface and that pavements may provide one of the longest-term records of geologic, hydrologic

  17. Children's personal exposure to air pollution in rural villages in Bhutan.

    PubMed

    Wangchuk, Tenzin; Mazaheri, Mandana; Clifford, Sam; Dudzinska, Marzenna R; He, Congrong; Buonanno, Giorgio; Morawska, Lidia

    2015-07-01

    Exposure assessment studies conducted in developing countries have been based on fixed-site monitoring to date. This is a major deficiency, leading to errors in estimating the actual exposures, which are a function of time spent and pollutant concentrations in different microenvironments. This study quantified school children's daily personal exposure to ultrafine particles (UFP) using real-time monitoring, as well as volatile organic compounds (VOCs) and NO2 using passive sampling in rural Bhutan in order to determine the factors driving the exposures. An activity diary was used to track children's time activity patterns, and difference in mean exposure levels across sex and indoor/outdoor were investigated with ANOVA. 82 children, attending three primary schools participated in this study; S1 and S2 during the wet season and S3 during the dry season. Mean daily UFP exposure (cm(-3)) was 1.08×10(4) for children attending S1, 9.81×10(3) for S2, and 4.19×10(4) for S3. The mean daily NO2 exposure (µgm(-3)) was 4.27 for S1, 3.33 for S2 and 5.38 for S3 children. Likewise, children attending S3 also experienced higher daily exposure to a majority of the VOCs than those attending S1 and S2. Time-series of UFP personal exposures provided detailed information on identifying sources of these particles and quantifying their contributions to the total daily exposures for each microenvironment. The highest UFP exposure resulted from cooking/eating, contributing to 64% of the daily exposure, due to firewood combustion in houses using traditional mud cookstoves. The lowest UFP exposures were during the hours that children spent outdoors at school. The outcomes of this study highlight the significant contributions of lifestyle and socio-economic factors in personal exposures and have applications in environmental risk assessment and household air pollution mitigation in Bhutan. PMID:26087435

  18. 10 CFR 850.24 - Exposure monitoring.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...workers' 8-hour TWA exposure levels by conducting personal breathing zone sampling. (2) Exposure monitoring results obtained...level. The monitoring must be conducted in a manner and at a frequency necessary to represent workers' exposure, as...

  19. 10 CFR 850.24 - Exposure monitoring.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...workers' 8-hour TWA exposure levels by conducting personal breathing zone sampling. (2) Exposure monitoring results obtained...level. The monitoring must be conducted in a manner and at a frequency necessary to represent workers' exposure, as...

  20. 10 CFR 850.24 - Exposure monitoring.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...workers' 8-hour TWA exposure levels by conducting personal breathing zone sampling. (2) Exposure monitoring results obtained...level. The monitoring must be conducted in a manner and at a frequency necessary to represent workers' exposure, as...

  1. 10 CFR 850.24 - Exposure monitoring.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...workers' 8-hour TWA exposure levels by conducting personal breathing zone sampling. (2) Exposure monitoring results obtained...level. The monitoring must be conducted in a manner and at a frequency necessary to represent workers' exposure, as...

  2. IMPORTANT FACTORS INFLUENCING CHILDREN'S EXPOSURE TO PESTICIDES

    EPA Science Inventory

    The Children's Exposure Research Program in the National Exposure Research Laboratory has supported numerous laboratory and field studies to reduce uncertainty in the exposure estimates with the goal of ensuring that pesticides are regulated appropriately. These studies were con...

  3. Exposure Control Plan Bloodborne Pathogen Program

    E-print Network

    Natelson, Douglas

    Exposure Control Plan Bloodborne Pathogen Program 1. Introduction 2. Occupational Exposure Bloodborne Pathogen Program 1. INTRODUCTION OSHA defines occupational exposure as reasonably anticipated skin set forth in the Bloodborne Pathogens (BBP) Standard are necessary to provide protection to employees

  4. SOURCES OF HUMAN EXPOSURE TO AIRBORNE PAH

    EPA Science Inventory

    Personal exposures to airborne particulate polycyclic aromatic hydrocarbons (PAHs) were studied in several populations in the US, Japan, and Czech Republic. Personal exposure monitors, developed for human exposure biomonitoring studies were used to collect fine particles (...

  5. 75 FR 44046 - Noise Exposure Map Acceptance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-27

    ...Aviation Administration Noise Exposure Map Acceptance ACTION: Notice...its determination that the noise exposure maps submitted by the City of Philadelphia Division...FAA's determination on the noise exposure maps is June 1, 2010. FOR FURTHER...

  6. Pulmonary function and clearance after prolonged sulfuric acid aerosol exposure

    SciTech Connect

    Ives, P.J. (ABB Environmental, Chapel Hill, NC (United States)); Gerrity, T.R.; DeWitt, P.; Folinsbee, L.J. (Environmental Protection Agency, Chapel Hill, NC (United States))

    1991-03-15

    The authors studied pulmonary function and clearance responses after a 4 H exposure to 75-100 {mu}g/m{sup 3} sulfuric acid aerosol (SAA). Healthy subjects, who exercised for 30 min/H at ventilation of about 25 L/min, were exposed once to clean air and once to SAA. Oral hygiene and acidic juice gargle were used to minimize oral ammonia. Lung function tests, including spirometry, plethysmography, and partial flow-volume (PEFV) curves were performed before and after exposure. Clearance of 99m-Technetium labeled iron oxide was assessed after each exposure. The first moment of fractional tracheobronchial retention (M1TBR), after correcting for 24 H retention and normalizing to time zero, was used as an index of clearance. There were no significant changes in lung volumes, airways resistance, or maximum expiratory flows after SAA exposure. Flow at 40% of total lung capacity on PEFV curves decreased 17% (NS) after SAA exposure. Tracheobronchial clearance was accelerated after a single exposure to SAA; M1TBR decreased from 73 {plus minus} 5 min (air) to 69 {plus minus} 5 min (SAA). These results suggest that acute prolonged exposure to low levels of SAA has minimal effects on lung mechanics in healthy subjects but does produce a modest acceleration of particle clearance.

  7. Evaluation of occupational exposures: a proposed sampling method.

    PubMed

    Brunn, I O; Campbell, J S; Hutzel, R L

    1986-04-01

    Occupational exposures to potentially hazardous agents may vary considerably because of worker mobility, or workplace contaminant levels that fluctuate within or between-days. In addition, individual susceptibility to adverse health effects varies among identically exposed workers. Therefore, accounting for these variables can be difficult during assessment of worker exposure for occupational health and OSHA compliance purposes. This is particularly true when there is varied and repeated exposure from day to day. A cost-effective monitoring strategy for evaluating repeated employee exposure and potential health risk that considers the foregoing exposure variables is desirable. The method this article proposes uses a well-planned sampling strategy featuring 4-hr, rather than the traditional 7 or 8-hr sampling durations. Use of 4-hr samples has been found to improve monitoring efficiency without significantly reducing sampling precision or accuracy. Statistical protocols applied during the sampling procedure and subsequent data analysis also combine to minimize the frequency and duration of samples required to reach a decision regarding the significance of a worker's exposure. The development of an Acceptable Risk Level (ARL) is another important element of the proposed method. An ARL is a variable based on risk assessment and risk management principles, which have been established by the employer for each contaminant. The ARL is dependent on the contaminant's toxicity and the time pattern and spacing of successive exposures. Ultimately, an ARL can be developed by an employer for the productive allocation of health and safety dollars to ensure worker protection. PMID:3706151

  8. 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

  9. Reproducibility of Reported In utero Exposure to Tobacco Smoke

    PubMed Central

    Cupul-Uicab, Lea A.; Ye, Xibiao; Skjaerven, Rolv; Haug, Kjell; Longnecker, Matthew P.

    2010-01-01

    PURPOSE In studies of the fetal origins of disease and life course epidemiology, measures of fetal exposure may be based on information reported by the adults who were exposed in utero. In particular, the full spectrum of consequences of in utero exposure to maternal tobacco smoking is now an area of active investigation, and the ability to report such exposure reproducibly is of interest. We evaluated the reproducibility of in utero exposure to tobacco smoke, reported by the adult daughter during consecutive pregnancies. METHODS This study was based on 11,257 women who enrolled for more than one pregnancy in the Norwegian Mother and Child Cohort Study (MoBa). Participants completed a questionnaire around 17 weeks of gestation, which asked about their in utero exposure to tobacco smoke. Kappa statistics were calculated. Determinants of agreement were evaluated using logistic regression. RESULTS Weighted Kappa for in utero exposure for the first and second reports was 0.80. Determinants of agreement were higher education (better) and longer time between reports (worse). CONCLUSIONS Information on in utero exposure to maternal tobacco smoking provided by adult women was highly reproducible in this population. PMID:21130369

  10. Occupational exposure to carbon black in its manufacture.

    PubMed

    Gardiner, K; Trethowan, W N; Harrington, J M; Calvert, I A; Glass, D C

    1992-10-01

    Carbon black is manufactured by the vapour phase pyrolysis of heavy aromatic hydrocarbon feedstocks. Its manufacture is worldwide and the majority of its production is for use in the rubber industry especially tyre manufacture. Its carbonaceous nature has led many to investigate the occurrence of exposure-related medical conditions. To quantify any such relationships, it is necessary to assess exposure accurately. As part of such an epidemiological investigation survey involving the measurement both of respirable and of total inhalable carbon black was undertaken in 18 plants in seven European countries between mid-1987 and mid-1989. A total of 1298 respirable samples (SIMPEDS cyclone) and 1317 total inhalable samples (IOM head) were taken and deemed of sufficient quality for inclusion in the study. The distributions of the time-weighted average values were assessed and found to be best described by a log-normal distribution, and so exposure is characterized by geometric means and standard deviations. The data are presented in terms of 13 separate job titles for both dust fractions and shows a wide variation between job titles, with the highest mean exposure experienced by the site cleaners, and 30% of the samples taken from the warehouse packers being in excess of the relevant countries' occupational exposure limits for total inhalable dust. The quality and extent of this data allows both for comparison with exposure standards and for generation of occupational exposure indices, which will be presented in another paper (Gardiner et al., in preparation). PMID:1444068

  11. Review and validation of exposure assessment methods 

    E-print Network

    Shaw, Eduardo

    2001-01-01

    to exposure reconstruction. Although there are several classes of exposure assessment methods, certain elements are common to almost all of them: (1) identify the causative agent, (2) identify groups of workers with similar exposures, (3) define exposure... project should be to estimate the exposure to each individual involved in the study. Since a study may involve hundreds, if not thousands of workers, the majority of epidemiologists are forced to group people who are thought to have similar exposure due...

  12. Vapor-induced phase separation—effect of the humid air exposure step on membrane morphology

    Microsoft Academic Search

    V. P. Khare; A. R. Greenberg; W. B. Krantz

    2005-01-01

    Vapor-induced phase separation (VIPS) involves a dry–wet casting process in which the dope solution is exposed to a nonsolvent vapor (often humid air) for a fixed time interval prior to immersion in a coagulation bath. Humid air exposure leads to a slow transfer of water from the vapor phase into the dope solution. By controlling the humid air exposure time,

  13. A NEW METHOD OF LONGITUDINAL DIARY ASSEMBLY FOR HUMAN EXPOSURE MODELING

    EPA Science Inventory

    Human exposure time-series modeling requires longitudinal time-activity diaries to evaluate the sequence of concentrations encountered, and hence, pollutant exposure for the simulated individuals. However, most of the available data on human activities are from cross-sectional su...

  14. Malignant lymphomas and occupational exposures.

    PubMed

    Persson, B; Dahlander, A M; Fredriksson, M; Brage, H N; Ohlson, C G; Axelson, O

    1989-08-01

    The effects of potential risk factors for Hodgkin's disease (HD) and for non-Hodgkin lymphomas (NHL) were evaluated in a case-referent study encompassing 54 cases of HD, 106 cases of NHL, and 275 referents, all alive. Exposure information was obtained by questionnaires posted to the subjects. Crude rate ratios were increased for various occupational exposures including solvents, welding, wood preservatives, phenoxy acids, and fresh wood (sawmill workers, lumberjacks, paper pulp workers). After further analyses based on logistic regression occupational exposures to welding and creosote remained as significant risk factors for HD. For NHL, occupational exposures to solvents, phenoxy acids, and creosote but also work as carpenter or cabinet maker and contacts with pets (other than dogs, cats, and birds) were associated with significantly increased risks. PMID:2775671

  15. ISSUES IN MONITORING POPULATION EXPOSURES

    EPA Science Inventory

    This manuscript explores the risks associated with exposure to carcinogenic chemicals that have become a growing source of public concern. Steadily increasing numbers of agents are being identified as mutagens and carcinogens. Furthermore, we are increasingly aware of sources of ...

  16. Women Veterans' Exposure to Combat

    Microsoft Academic Search

    Stephen J. Dienstfrey

    1988-01-01

    Using data collected in the Veterans Administration's Survey of Female Veterans, this article describes the characteristics of women veterans who were exposed to combat situations while serving in the armed forces. The definition of combat exposure ranges from \\

  17. Occupational radiation exposure: population studies.

    PubMed

    Schleipman, A Robert

    2005-01-01

    Occupational exposure to ionizing radiation in the medical setting differs from the acute exposure received by survivors of atomic bomb blasts. Yet, atomic bomb survivors' disease and mortality outcomes have been the standard data source on the effects of ionizing radiation on humans. Therefore, the prevailing estimated risks of ionizing radiation may not apply to radiologic technologists and other medical radiation workers. Carefully designed epidemiological trials provide evidence that helps determine the strength of association between exposure and onset of disease in selected populations. This article reviews radiation effects, explains some basic design concepts of epidemiologic trials and surveys the epidemiology literature related to radiation exposure to humans, with special attention to radiology staff. PMID:15732889

  18. MAPPING CLIMATE CHANGE EXPOSURES, VULNERABILITIES,

    E-print Network

    MAPPING CLIMATE CHANGE EXPOSURES, VULNERABILITIES, AND ADAPTATION TO PUBLIC HEALTH RISKS's California Climate Change Center JULY 2012 CEC5002012041 Prepared for: California Energy Commission of California. #12; ii ABSTRACT This study reviewed first available frameworks for climate change adaptation

  19. Effect and use of exposure control in vibration analysis using TV holography

    NASA Astrophysics Data System (ADS)

    Rosvold, Geir O.; Lokberg, Ole J.

    1993-02-01

    A time-averaged recording of a sinusoidally vibrating object reconstructs a fringe function, which is determined by the ratio between the exposure time and the vibration period. For short exposures, compared with the vibration period, the fringe function is highly dependent on the number of vibration cycles recorded and on the starting point of the exposure in the vibration cycle. When several fringe functions that are recorded at different parts of the vibration cycle are added, the resulting averaged fringe function is similar to the normal J(0)-squared function, even at short exposures. The frequency ranges at which numerical analysis can be used in these two cases are defined, and the result of short exposures permitting digital fringe analysis, even under extremely unstable situation, is demonstrated. Extending the standard video exposure time permits recording vibrations at low frequencies as the normal J(0)-squared function and improves the light economy.

  20. Effect and use of exposure control in vibration analysis using TV holography.

    PubMed

    Rosvold, G O; Løkberg, O J

    1993-02-10

    A time-averaged recording of a sinusoidally vibrating object reconstructs a fringe function, which is determined by the ratio between the exposure time and the vibration period. For short exposures, compared with the vibration period, the fringe function is highly dependent on the number of vibration cycles recorded and on the starting point of the exposure in the vibration cycle. When several fringe functions that are recorded at different parts of the vibration cycle are added, the resulting averaged fringe function is similar to the normal J(o)(2) function, even at short exposures. The frequency ranges at which numerical analysis can be used in these two cases are defined, and the result of short exposures permitting digital fringe analysis, even under extremely unstable situations, is demonstrated. Extending the standard video exposure time permits recording vibrations at low frequencies as the normal J(o)(2) function and improves the light economy. PMID:20802740

  1. Mathematical modeling of inhalation exposure

    NASA Technical Reports Server (NTRS)

    Fiserova-Bergerova, V.

    1976-01-01

    The paper presents a mathematical model of inhalation exposure in which uptake, distribution and excretion are described by exponential functions, while rate constants are determined by tissue volumes, blood perfusion and by the solubility of vapors (partition coefficients). In the model, tissues are grouped into four pharmokinetic compartments. The model is used to study continuous and interrupted chronic exposures and is applied to the inhalation of Forane and methylene chloride.

  2. Environmental monitoring of secondhand smoke exposure

    PubMed Central

    Apelberg, Benjamin J; Hepp, Lisa M; Avila-Tang, Erika; Gundel, Lara; Hammond, S Katharine; Hovell, Melbourne F; Hyland, Andrew; Klepeis, Neil E; Madsen, Camille C; Navas-Acien, Ana; Repace, James; Samet, Jonathan M

    2013-01-01

    The complex composition of secondhand smoke (SHS) provides a range of constituents that can be measured in environmental samples (air, dust and on surfaces) and therefore used to assess non-smokers' exposure to tobacco smoke. Monitoring SHS exposure (SHSe) in indoor environments provides useful information on the extent and consequences of SHSe, implementing and evaluating tobacco control programmes and behavioural interventions, and estimating overall burden of disease caused by SHSe. The most widely used markers have been vapour-phase nicotine and respirable particulate matter (PM). Numerous other environmental analytes of SHS have been measured in the air including carbon monoxide, 3-ethenylpyridine, polycyclic aromatic hydrocarbons, tobacco-specific nitrosamines, nitrogen oxides, aldehydes and volatile organic compounds, as well as nicotine in dust and on surfaces. The measurement of nicotine in the air has the advantage of reflecting the presence of tobacco smoke. While PM measurements are not as specific, they can be taken continuously, allowing for assessment of exposure and its variation over time. In general, when nicotine and PM are measured in the same setting using a common sampling period, an increase in nicotine concentration of 1??g/m3 corresponds to an average increase of 10??g/m3 of PM. This topic assessment presents a comprehensive summary of SHSe monitoring approaches using environmental markers and discusses the strengths and weaknesses of these methods and approaches. PMID:22949497

  3. 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. PMID:17878926

  4. Environmental source of arsenic exposure.

    PubMed

    Chung, Jin-Yong; Yu, Seung-Do; Hong, Young-Seoub

    2014-09-01

    Arsenic is a ubiquitous, naturally occurring metalloid that may be a significant risk factor for cancer after exposure to contaminated drinking water, cigarettes, foods, industry, occupational environment, and air. Among the various routes of arsenic exposure, drinking water is the largest source of arsenic poisoning worldwide. Arsenic exposure from ingested foods usually comes from food crops grown in arsenic-contaminated soil and/or irrigated with arsenic-contaminated water. According to a recent World Health Organization report, arsenic from contaminated water can be quickly and easily absorbed and depending on its metabolic form, may adversely affect human health. Recently, the US Food and Drug Administration regulations for metals found in cosmetics to protect consumers against contaminations deemed deleterious to health; some cosmetics were found to contain a variety of chemicals including heavy metals, which are sometimes used as preservatives. Moreover, developing countries tend to have a growing number of industrial factories that unfortunately, harm the environment, especially in cities where industrial and vehicle emissions, as well as household activities, cause serious air pollution. Air is also an important source of arsenic exposure in areas with industrial activity. The presence of arsenic in airborne particulate matter is considered a risk for certain diseases. Taken together, various potential pathways of arsenic exposure seem to affect humans adversely, and future efforts to reduce arsenic exposure caused by environmental factors should be made. PMID:25284196

  5. Statistical analysis of a dynamic model for dietary contaminant exposure.

    PubMed

    Bertail, P; Clémençon, S; Tressou, J

    2010-03-01

    This paper is devoted to the statistical analysis of a stochastic model introduced in [P. Bertail, S. Clémençon, and J. Tressou, A storage model with random release rate for modelling exposure to food contaminants, Math. Biosci. Eng. 35 (1) (2008), pp. 35-60] for describing the phenomenon of exposure to a certain food contaminant. In this modelling, the temporal evolution of the contamination exposure is entirely determined by the accumulation phenomenon due to successive dietary intakes and the pharmacokinetics governing the elimination process inbetween intakes, in such a way that the exposure dynamic through time is described as a piecewise deterministic Markov process. Paths of the contamination exposure process are scarcely observable in practice, therefore intensive computer simulation methods are crucial for estimating the time-dependent or steady-state features of the process. Here we consider simulation estimators based on consumption and contamination data and investigate how to construct accurate bootstrap confidence intervals (CI) for certain quantities of considerable importance from the epidemiology viewpoint. Special attention is also paid to the problem of computing the probability of certain rare events related to the exposure process path arising in dietary risk analysis using multilevel splitting or importance sampling (IS) techniques. Applications of these statistical methods to a collection of data sets related to dietary methyl mercury contamination are discussed thoroughly. PMID:22876987

  6. Further studies of 60 Hz exposure effects on human function

    SciTech Connect

    Graham, C.; Cohen, H.D.

    1990-10-09

    Public concern has been expressed about possible health risks arising from exposure to the electric and magnetic fields generated power distribution systems. This project is addressing this concern through a laboratory research program designed to evaluate the effects of brief exposure to known field conditions on multiple measures of human function. In previous research, we found that exposure had statistically significant effects on physiological measures of cardiac and brain activity, and on performance measures of reaction time and performance accuracy. Effects were seen more clearly under intermittent exposure conditions, and at certain levels of electric and magnetic field strength. In this continuation effort, we are performing a series of exploratory studies, to be followed by a confirmatory experiment, to determine if the above physiological effects differ as a function of exposure to the electric and magnetic fields separately and combined, time of day, and rate of intermittent exposure. Further studies will explore the mechanisms underlying these effects. The information developed in this project will be of value in risk assessment activities, and in basic research aimed at identifying specific factors involved in the interaction of power line fields with the human system. In this reporting period our goals were to: (a) continue performance of the probe studies; (b) participate in a site visit at MRI; (c) request 1991 research continuation funding; and (d) submit an abstract of project findings for presentation at the 1990 DOE Contractors Review Meeting.

  7. Temporal observations of bright soil exposures at Gusev crater, Mars

    USGS Publications Warehouse

    Rice, M.S.; Bell, J.F.; Cloutis, E.A.; Wray, J.J.; Herkenhoff, K.E.; Sullivan, R.; Johnson, J.R.; Anderson, R.B.

    2011-01-01

    The Mars Exploration Rover Spirit has discovered bright soil deposits in its wheel tracks that previously have been confirmed to contain ferric sulfates and/or opaline silica. Repeated Pancam multispectral observations have been acquired at four of these deposits to monitor spectral and textural changes over time during exposure to Martian surface conditions. Previous studies suggested that temporal spectral changes occur because of mineralogic changes (e.g., phase transitions accompanying dehydration). In this study, we present a multispectral and temporal analysis of eight Pancam image sequences at the Tyrone exposure, three at the Gertrude Weise exposure, two at the Kit Carson exposure, and ten at the Ulysses exposure that have been acquired as of sol 2132 (1 January 2010). We compare observed variations in Pancam data to spectral changes predicted by laboratory experiments for the dehydration of ferric sulfates. We also present a spectral analysis of repeated Mars Reconnaissance Orbiter HiRISE observations spanning 32 sols and a textural analysis of Spirit Microscopic Imager observations of Ulysses spanning 102 sols. At all bright soil exposures, we observe no statistically significant spectral changes with time that are uniquely diagnostic of dehydration and/or mineralogic phase changes. However, at Kit Carson and Ulysses, we observe significant textural changes, including slumping within the wheel trench, movement of individual grains, disappearance of fines, and dispersal of soil clods. All observed textural changes are consistent with aeolian sorting and/or minor amounts of air fall dust deposition. Copyright 2011 by the American Geophysical Union.

  8. Temporal observations of bright soil exposures at Gusev crater, Mars

    USGS Publications Warehouse

    Rice, M.S.; Bell, J.F., III; Cloutis, E.A.; Wray, J.J.; Herkenhoff, K.E.; Sullivan, R.; Johnson, J.R.; Anderson, R.B.

    2011-01-01

    The Mars Exploration Rover Spirit has discovered bright soil deposits in its wheel tracks that previously have been confirmed to contain ferric sulfates and/or opaline silica. Repeated Pancam multispectral observations have been acquired at four of these deposits to monitor spectral and textural changes over time during exposure to Martian surface conditions. Previous studies suggested that temporal spectral changes occur because of mineralogic changes (e.g., phase transitions accompanying dehydration). In this study, we present a multispectral and temporal analysis of eight Pancam image sequences at the Tyrone exposure, three at the Gertrude Weise exposure, two at the Kit Carson exposure, and ten at the Ulysses exposure that have been acquired as of sol 2132 (1 January 2010). We compare observed variations in Pancam data to spectral changes predicted by laboratory experiments for the dehydration of ferric sulfates. We also present a spectral analysis of repeated Mars Reconnaissance Orbiter HiRISE observations spanning 32 sols and a textural analysis of Spirit Microscopic Imager observations of Ulysses spanning 102 sols. At all bright soil exposures, we observe no statistically significant spectral changes with time that are uniquely diagnostic of dehydration and/or mineralogic phase changes. However, at Kit Carson and Ulysses, we observe significant textural changes, including slumping within the wheel trench, movement of individual grains, disappearance of fines, and dispersal of soil clods. All observed textural changes are consistent with aeolian sorting and/or minor amounts of air fall dust deposition.

  9. Occupational exposure to fluorinated hydrocarbons during refrigeration repair work.

    PubMed

    Gjølstad, Merete; Ellingsen, Dag G; Espeland, Oscar; Nordby, Karl-Christian; Evenseth, Harald; Thorud, Syvert; Skaugset, Nils Petter; Thomassen, Yngvar

    2003-04-01

    This study describes refrigeration repair workers' occupational exposures to halogenated refrigerants, focusing on difluorochloromethane (HCFC 22), tetrafluoroethane (HFC 134a) and a mixture of tri-, tetra- and pentafluoroethane (R404A) in 30 work operations. Unlike earlier reported studies, the present study includes working procedures involving welding in order to measure possible occupational exposure to decomposition products. The measurements included hydrogen fluoride (HF), hydrogen chloride (HCl), phosgene (COCl2) and volatile organic compounds (VOC). The exposures were assessed during work operations on small-scale cooling installations like refrigerators and freezers. The repair workers' occupational exposures to refrigerants were moderate, and the major part of the exposures were associated with specific working procedures lasting for relatively short periods of time (<20 min). During these exposure events the concentrations were occasionally high (up to 42434 mg m(-3)). Although welding operations lasted only for short periods of time, HF was detected in 9 out of 15 samples when HCFC 22, HFC 134a or R404A had been used. Hydrogen chloride was detected in 3 out of 5 samples in air polluted with HCFC 22. Phosgene was not detected. A large number of VOCs in various concentrations were found during welding. Except for the applied refrigerants, halogenated compounds were only found in one sample. PMID:12729261

  10. Ultra-accelerated natural sunlight exposure testing facilities

    DOEpatents

    Lewandowski, Allan A.; Jorgensen, Gary J.

    2003-08-12

    A multi-faceted concentrator apparatus for providing ultra-accelerated natural sunlight exposure testing for sample materials under controlled weathering conditions comprising: facets that receive incident natural sunlight, transmits VIS/NIR and reflects UV/VIS to deliver a uniform flux of UV/VIS onto a sample exposure plane located near a center of a facet array in chamber means that provide concurrent levels of temperature and/or relative humidity at high levels of up to 100.times. of natural sunlight that allow sample materials to be subjected to accelerated irradiance exposure factors for a significant period of time of about 3 to 10 days to provide a corresponding time of about at least a years worth representative weathering of sample materials.

  11. Ultra-Accelerated Natural Sunlight Exposure Testing Facilities

    DOEpatents

    Lewandowski, Allan A. (Evergreen, CO); Jorgensen, Gary J. (Pine, CO)

    2004-11-23

    A multi-faceted concentrator apparatus for providing ultra-accelerated natural sunlight exposure testing for sample materials under controlled weathering conditions comprising: facets that receive incident natural sunlight, transmits VIS/NIR and reflects UV/VIS onto a secondary reflector that delivers a uniform flux of UV/VIS onto a sample exposure plane located near a center of a facet array in a chamber that provide concurrent levels of temperature and/or relative humidity at high levels of up to 100.times. of natural sunlight that allow sample materials to be subjected to accelerated irradiance exposure factors for a significant period of time of about 3 to 10 days to provide a corresponding time of about at least a years worth representative weathering of sample materials.

  12. Formal recycling of e-waste leads to increased exposure to toxic metals: an occupational exposure study from Sweden.

    PubMed

    Julander, Anneli; Lundgren, Lennart; Skare, Lizbet; Grandér, Margaretha; Palm, Brita; Vahter, Marie; Lidén, Carola

    2014-12-01

    Electrical and electronic waste (e-waste) contains multiple toxic metals. However, there is currently a lack of exposure data for metals on workers in formal recycling plants. The objective of this study was to evaluate workers' exposure to metals, using biomarkers of exposure in combination with monitoring of personal air exposure. We assessed exposure to 20 potentially toxic metals among 55 recycling workers and 10 office workers at three formal e-waste recycling plants in Sweden. Workers at two of the plants were followed-up after 6 months. We collected the inhalable fraction and OFC (37-mm) fraction of particles, using personal samplers, as well as spot samples of blood and urine. We measured metal concentrations in whole blood, plasma, urine, and air filters using inductively coupled plasma-mass spectrometry following acid digestion. The air sampling indicated greater airborne exposure, 10 to 30 times higher, to most metals among the recycling workers handling e-waste than among the office workers. The exposure biomarkers showed significantly higher concentrations of chromium, cobalt, indium, lead, and mercury in blood, urine, and/or plasma of the recycling workers, compared with the office workers. Concentrations of antimony, indium, lead, mercury, and vanadium showed close to linear associations between the inhalable particle fraction and blood, plasma, or urine. In conclusion, our study of formal e-waste recycling shows that workers performing recycling tasks are exposed to multiple toxic metals. PMID:25300751

  13. Modeling personal particle-bound polycyclic aromatic hydrocarbon (pb-pah) exposure in human subjects in Southern California

    PubMed Central

    2012-01-01

    Background Exposure to polycyclic aromatic hydrocarbon (PAH) has been linked to various adverse health outcomes. Personal PAH exposures are usually measured by personal monitoring or biomarkers, which are costly and impractical for a large population. Modeling is a cost-effective alternative to characterize personal PAH exposure although challenges exist because the PAH exposure can be highly variable between locations and individuals in non-occupational settings. In this study we developed models to estimate personal inhalation exposures to particle-bound PAH (PB-PAH) using data from global positioning system (GPS) time-activity tracking data, traffic activity, and questionnaire information. Methods We conducted real-time (1-min interval) personal PB-PAH exposure sampling coupled with GPS tracking in 28 non-smoking women for one to three sessions and one to nine days each session from August 2009 to November 2010 in Los Angeles and Orange Counties, California. Each subject filled out a baseline questionnaire and environmental and behavior questionnaires on their typical activities in the previous three months. A validated model was used to classify major time-activity patterns (indoor, in-vehicle, and other) based on the raw GPS data. Multiple-linear regression and mixed effect models were developed to estimate averaged daily and subject-level PB-PAH exposures. The covariates we examined included day of week and time of day, GPS-based time-activity and GPS speed, traffic- and roadway-related parameters, meteorological variables (i.e. temperature, wind speed, relative humidity), and socio-demographic variables and occupational exposures from the questionnaire. Results We measured personal PB-PAH exposures for 180?days with more than 6 h of valid data on each day. The adjusted R2 of the model was 0.58 for personal daily exposures, 0.61 for subject-level personal exposures, and 0.75 for subject-level micro-environmental exposures. The amount of time in vehicle (averaging 4.5% of total sampling time) explained 48% of the variance in daily personal PB-PAH exposure and 39% of the variance in subject-level exposure. The other major predictors of PB-PAH exposures included length-weighted traffic count, work-related exposures, and percent of weekday time. Conclusion We successfully developed regression models to estimate PB-PAH exposures based on GPS-tracking data, traffic data, and simple questionnaire information. Time in vehicle was the most important determinant of personal PB-PAH exposure in this population. We demonstrated the importance of coupling real-time exposure measures with GPS time-activity tracking in personal air pollution exposure assessment. PMID:22784481

  14. Comparison of personal radio frequency electromagnetic field exposure in different urban areas across Europe

    SciTech Connect

    Joseph, Wout, E-mail: wout.joseph@intec.UGent.be [Department of Information Technology, Ghent University/IBBT Gaston Crommenlaan 8, B-9050 Ghent (Belgium)] [Department of Information Technology, Ghent University/IBBT Gaston Crommenlaan 8, B-9050 Ghent (Belgium); Frei, Patrizia; Rooesli, Martin [Swiss Tropical and Public Health Institute Basel (Switzerland) [Swiss Tropical and Public Health Institute Basel (Switzerland); University of Basel (Switzerland); Thuroczy, Gyoergy [Department of Non-ionizing Radiation, National Research Institute for Radiobiology and Radiohygiene, Pf. 101, Budapest 1775 (Hungary) [Department of Non-ionizing Radiation, National Research Institute for Radiobiology and Radiohygiene, Pf. 101, Budapest 1775 (Hungary); French National Institute for Industrial Environment and Risks (INERIS), Verneuil en Halatte (France); Gajsek, Peter; Trcek, Tomaz [Institute of Non-ionizing Radiation, 1000 Ljubljana (Slovenia)] [Institute of Non-ionizing Radiation, 1000 Ljubljana (Slovenia); Bolte, John [Laboratory for Radiation Research, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands, (Netherlands)] [Laboratory for Radiation Research, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands, (Netherlands); Vermeeren, Guenter [Department of Information Technology, Ghent University/IBBT Gaston Crommenlaan 8, B-9050 Ghent (Belgium)] [Department of Information Technology, Ghent University/IBBT Gaston Crommenlaan 8, B-9050 Ghent (Belgium); Mohler, Evelyn [Swiss Tropical and Public Health Institute Basel (Switzerland) [Swiss Tropical and Public Health Institute Basel (Switzerland); University of Basel (Switzerland); Juhasz, Peter [Department of Non-ionizing Radiation, National Research Institute for Radiobiology and Radiohygiene, Pf. 101, Budapest 1775 (Hungary)] [Department of Non-ionizing Radiation, National Research Institute for Radiobiology and Radiohygiene, Pf. 101, Budapest 1775 (Hungary); Finta, Viktoria [Eoetvoes Lorand University, Faculty of Science, Institute of Physics, Department of Atomic Physics Address 1117 Budapest, Pazmany Peter setany 1/A (Hungary)] [Eoetvoes Lorand University, Faculty of Science, Institute of Physics, Department of Atomic Physics Address 1117 Budapest, Pazmany Peter setany 1/A (Hungary); Martens, Luc [Department of Information Technology, Ghent University/IBBT Gaston Crommenlaan 8, B-9050 Ghent (Belgium)] [Department of Information Technology, Ghent University/IBBT Gaston Crommenlaan 8, B-9050 Ghent (Belgium)

    2010-10-15

    Background: Only limited data are available on personal radio frequency electromagnetic field (RF-EMF) exposure in everyday life. Several European countries performed measurement studies in this area of research. However, a comparison between countries regarding typical exposure levels is lacking. Objectives: To compare for the first time mean exposure levels and contributions of different sources in specific environments between different European countries. Methods: In five countries (Belgium, Switzerland, Slovenia, Hungary, and the Netherlands), measurement studies were performed using the same personal exposure meters. The pooled data were analyzed using the robust regression on order statistics (ROS) method in order to allow for data below the detection limit. Mean exposure levels were compared between different microenvironments such as homes, public transports, or outdoor. Results: Exposure levels were of the same order of magnitude in all countries and well below the international exposure limits. In all countries except for the Netherlands, the highest total exposure was measured in transport vehicles (trains, car, and busses), mainly due to radiation from mobile phone handsets (up to 97%). Expo