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1

Major Radiodiagnostic Imaging in Pregnancy and the Risk of Childhood Malignancy: A Population-Based Cohort Study in Ontario  

PubMed Central

Background The association between fetal exposure to major radiodiagnostic testing in pregnancy—computed tomography (CT) and radionuclide imaging—and the risk of childhood cancer is not established. Methods and Findings We completed a population-based study of 1.8 million maternal-child pairs in the province of Ontario, from 1991 to 2008. We used Ontario's universal health care–linked administrative databases to identify all term obstetrical deliveries and newborn records, inpatient and outpatient major radiodiagnostic services, as well as all children with a malignancy after birth. There were 5,590 mothers exposed to major radiodiagnostic testing in pregnancy (3.0 per 1,000) and 1,829,927 mothers not exposed. The rate of radiodiagnostic testing increased from 1.1 to 6.3 per 1,000 pregnancies over the study period; about 73% of tests were CT scans. After a median duration of follow-up of 8.9 years, four childhood cancers arose in the exposed group (1.13 per 10,000 person-years) and 2,539 cancers in the unexposed group (1.56 per 10,000 person-years), a crude hazard ratio of 0.69 (95% confidence interval 0.26–1.82). After adjusting for maternal age, income quintile, urban status, and maternal cancer, as well as infant sex, chromosomal or congenital anomalies, and major radiodiagnostic test exposure after birth, the risk was essentially unchanged (hazard ratio 0.68, 95% confidence interval 0.25–1.80). Conclusions Although major radiodiagnostic testing is now performed in about 1 in 160 pregnancies in Ontario, the absolute annual risk of childhood malignancy following exposure in utero remains about 1 in 10,000. Since the upper confidence limit of the relative risk of malignancy may be as high as 1.8 times that of an unexposed pregnancy, we cannot exclude the possibility that fetal exposure to CT or radionuclide imaging is carcinogenic. Please see later in the article for the Editors' Summary PMID:20838660

Ray, Joel G.; Schull, Michael J.; Urquia, Marcelo L.; You, John J.; Guttmann, Astrid; Vermeulen, Marian J.

2010-01-01

2

Bisamide bisthiol compounds useful for making technetium radiodiagnostic renal agents  

DOEpatents

A radiodiagnostic bisamido-bisthio ligand useful for producing Tc-labelled radiodiagnostic renal agents is described. The ligand forms a complex with the radionuclide .sup.99m Tc suitable for administration as a radiopharmaceutical to obtain images of the kidney for diagnosis of kidney disfunction.

Davison, Alan (Needham, MA); Brenner, David (Cambridge, MA); Lister-James, John (Cambridge, MA); Jones, Alun G. (Newton Centre, MA)

1987-06-16

3

Fast exposure time decision in multi-exposure HDR imaging  

NASA Astrophysics Data System (ADS)

Currently available imaging and display system exists the problem of insufficient dynamic range, and the system cannot restore all the information for an high dynamic range (HDR) scene. The number of low dynamic range(LDR) image samples and fastness of exposure time decision impacts the real-time performance of the system dramatically. In order to realize a real-time HDR video acquisition system, this paper proposed a fast and robust method for exposure time selection in under and over exposure area which is based on system response function. The method utilized the monotony of the imaging system. According to this characteristic the exposure time is adjusted to an initial value to make the median value of the image equals to the middle value of the system output range; then adjust the exposure time to make the pixel value on two sides of histogram be the middle value of the system output range. Thus three low dynamic range images are acquired. Experiments show that the proposed method for adjusting the initial exposure time can converge in two iterations which is more fast and stable than average gray control method. As to the exposure time adjusting in under and over exposed area, the proposed method can use the dynamic range of the system more efficiently than fixed exposure time method.

Piao, Yongjie; Jin, Guang

2012-10-01

4

The ASTROSAT/UVIT Exposure Time Calculator  

NASA Astrophysics Data System (ADS)

ASTROSAT is India's broad-spectral-band astronomy satellite. The Ultraviolet Imaging Telescope (UVIT) on ASTROSAT provides UV and optical (120 to 550 nm) coverage. The UVIT exposure time calculator was developed to enable planning of observations with the UVIT instrument of various astronomical sources of UV radiation. Here, the UVIT exposure time calculator is described.

Leahy, D.

2014-05-01

5

Technetium radiodiagnostic fatty acids derived from bisamide bisthiol ligands  

DOEpatents

A bisamide-bisthiol ligand containing fatty acid substituted thiol useful for producing Tc-labelled radiodiagnostic imaging agents is described. The ligand forms a complex with the radionuclide .sup.99m Tc suitable for administration as a radiopharmaceutical to obtain images of the heart for diagnosis of myocardial disfunction.

Jones, Alun G. (Newton Centre, MA); Lister-James, John (Wellesley, MA); Davison, Alan (Needham, MA)

1988-05-24

6

Exposure influences expressive timing judgments in music.  

PubMed

This study is concerned with the question whether, and to what extent, listeners' previous exposure to music in everyday life, and expertise as a result of formal musical training, play a role in making expressive timing judgments in music. This was investigated by using a Web-based listening experiment in which listeners with a wide range of musical backgrounds were asked to compare 2 recordings of the same composition (15 pairs, grouped in 3 musical genres), 1 of which was tempo-transformed (manipulating the expressive timing). The results show that expressive timing judgments are not so much influenced by expertise levels, as is suggested by the expertise hypothesis, but by exposure to a certain musical idiom, as is suggested by the exposure hypothesis. As such, the current study provides evidence for the idea that some musical capabilities are acquired through mere exposure to music, and that these abilities are more likely enhanced by active listening (exposure) than by formal musical training (expertise). PMID:19170488

Honing, Henkjan; Ladinig, Olivia

2009-02-01

7

Exposure Influences Expressive Timing Judgments in Music  

Microsoft Academic Search

This study is concerned with the question whether, and to what extent, listeners' previous exposure to music in everyday life, and expertise as a result of formal musical training, play a role in making expressive timing judgments in music. This was investigated by using a Web-based listening experiment in which listeners with a wide range of musical backgrounds were asked

Henkjan Honing; Olivia Ladinig

2009-01-01

8

The WFIRST Galaxy Survey Exposure Time Calculator  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

9

MEASUREMENT AND DECOMPOSITION OF TOTAL EXPOSURE USING THE TOTAL-ISOLATED-BY-MICROENVIRONMENT-EXPOSURE (TIME) MONITOR  

EPA Science Inventory

This paper describes a new, highly compact and lightweight monitor that directly measures personal exposure resolved into four microenvironments. he device is the "Total-Isolated-by-Microenvironment-Exposure (TIME)" monitor. he monitor can identify electronically a subject's micr...

10

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

ERIC Educational Resources Information Center

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)

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

1975-01-01

11

Real time chemical exposure and risk monitor  

DOEpatents

The apparatus of the present invention is a combination of a breath interface and an external exposure dosimeter interface to a chemical analysis device, all controlled by an electronic processor for quantitatively analyzing chemical analysis data from both the breath interface and the external exposure dosimeter for determining internal tissue dose. The method of the present invention is a combination of steps of measuring an external dose, measuring breath content, then analyzing the external dose and breath content and determining internal tissue dose. 7 figs.

Thrall, K.D.; Kenny, D.V.; Endres, G.W.R.; Sisk, D.R.

1997-07-08

12

Sources of time-varying exchange rate exposure  

Microsoft Academic Search

We report evidence of a time-varying link between returns on national stock market indexes and exchange rate returns (exchange\\u000a rate exposure). We use this evidence to analyze the sources of changes over time in exchange rate exposure. Using monthly\\u000a data for 14 industrialized countries for the period 1975–2006, we report evidence of a cointegration relation between exchange\\u000a rate exposure and

Christian Pierdzioch; Renatas Kizys

2010-01-01

13

Exposure Time Optimization for Highly Dynamic Star Trackers  

PubMed Central

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

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

2014-01-01

14

Correcting for Exposure Misclassification Using Survival Analysis with a Time-varying Exposure  

PubMed Central

Purpose Survival analysis is increasingly being used in perinatal epidemiology to assess time-varying risk factors for various pregnancy outcomes. Here we show how quantitative correction for exposure misclassification can be applied to a Cox regression model with a time-varying dichotomous exposure. Methods We evaluated influenza vaccination during pregnancy in relation to preterm birth among 2,267 non-malformed infants whose mothers were interviewed as part of the Slone Birth Defects Study during 2006–2011. The hazard of preterm birth was modeled using a time-varying exposure Cox regression model with gestational age as the time-scale. The effect of exposure misclassification was then modeled using a probabilistic bias analysis that incorporated vaccination date assignment. The parameters for the bias analysis were derived from both internal and external validation data. Results Correction for misclassification of prenatal influenza vaccination resulted in an adjusted hazard ratio (AHR) slightly higher and less precise than the conventional analysis: bias corrected AHR 1.04 [95% simulation interval 0.70, 1.52]; conventional AHR 1.00 [95% confidence interval 0.71, 1.41]. Conclusion Probabilistic bias analysis allows epidemiologists to assess quantitatively the possible confounder-adjusted effect of misclassification of a time-varying exposure, in contrast to a speculative approach to understanding information bias. PMID:23041654

Ahrens, Katherine; Lash, Timothy L.; Louik, Carol; Mitchell, Allen A.; Werler, Martha M.

2012-01-01

15

IDENTIFICATION OF TIME-INTEGRATED SAMPLING AND MEASUREMENT TECHNIQUES TO SUPPORT HUMAN EXPOSURE STUDIES  

EPA Science Inventory

Accurate exposure classification tools are required to link exposure with health effects in epidemiological studies. Long-term, time-integrated exposure measures would be desirable to address the problem of developing appropriate residential childhood exposure classifications. ...

16

Novel Monitor Paradigm for Real-Time Exposure Assessment  

PubMed Central

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

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

2013-01-01

17

TIME-INTEGRATED EXPOSURE MEASURES TO IMPROVE THE PREDICTIVE POWER OF EXPOSURE CLASSIFICATION FOR EPIDEMIOLOGIC STUDIES  

EPA Science Inventory

Accurate exposure classification tools are required to link exposure with health effects in epidemiological studies. Although long-term integrated exposure measurements are a critical component of exposure assessment, the ability to include these measurements into epidemiologic...

18

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

PubMed

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

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

2004-12-01

19

Time–space modeling of journey-time exposure to traffic-related air pollution using GIS  

Microsoft Academic Search

Journey-time exposures represent an important, though as yet little-studied, component of human exposure to traffic-related air pollution, potentially with important health effects. Methods for assessing journey-time exposures, either as part of epidemiological studies or for policy assessment, are, however, poorly developed. This paper describes the development and testing of a GIS-based system for modeling human journey-time exposures to traffic-related air

John Gulliver; David J. Briggs

2005-01-01

20

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

PubMed Central

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

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

2014-01-01

21

Children's Television Exposure and Behavioral and Social Outcomes at 5.5 Years: Does Timing of Exposure Matter?  

Microsoft Academic Search

BACKGROUND. The American Academy of Pediatrics recommends children 2 years of age limit daily media exposure to 1 to 2 hours and not have a television set in children's bedrooms. However, there are limited prospective studies to address how timing of media exposure influences children's health. OBJECTIVE. Our goal was to examine relations among children's early, concurrent, and sustained television

Kamila B. Mistry; Cynthia S. Minkovitz; Donna M. Strobino; Dina L. G. Borzekowski

2010-01-01

22

Time-space modeling of journey-time exposure to traffic-related air pollution using GIS.  

PubMed

Journey-time exposures represent an important, though as yet little-studied, component of human exposure to traffic-related air pollution, potentially with important health effects. Methods for assessing journey-time exposures, either as part of epidemiological studies or for policy assessment, are, however, poorly developed. This paper describes the development and testing of a GIS-based system for modeling human journey-time exposures to traffic-related air pollution: STEMS (Space-Time Exposure Modeling System). The model integrates data on source activity, pollutant dispersion, and travel behavior to derive individual- or group-level exposure measures to atmospheric pollution. The model, which is designed to simulate exposures of people as they move through a changing air pollution field, was developed, validated, and trialed in Northampton, UK. The system currently uses ArcInfo to couple four separate submodels: a source activity/emission model (SATURN), a proprietary atmospheric dispersion model (ADMS-Urban), an empirically derived background air pollution model, and a purposely designed time-activity-based exposure model (TOTEM). This paper describes the structure of the modeling system; presents results of field calibration, validation, and sensitivity analysis; and illustrates the use of the model to analyze journey-time exposures of schoolchildren. PMID:15476729

Gulliver, John; Briggs, David J

2005-01-01

23

Exposure Measurement Error in Time-Series Studies of Air Pollution: Concepts and Consequences  

E-print Network

1 Exposure Measurement Error in Time-Series Studies of Air Pollution: Concepts and Consequences S in time-series studies 1 11/11/99 Keywords: measurement error, air pollution, time series, exposure of air pollution and health. Because measurement error may have substantial implications for interpreting

Dominici, Francesca

24

Retention of Idioms Following One-Time Exposure  

ERIC Educational Resources Information Center

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…

Reuterskiold, Christina; Van Lancker Sidtis, Diana

2013-01-01

25

Influence of summer daylight saving time on scattered erythemal solar ultraviolet exposures.  

PubMed

The research question of whether there are any influences in the scattered or diffuse erythemal UV exposures to a horizontal plane over a five month period due to the change from standard time to daylight saving time, has been investigated by using physical measurements and applying them to both standard time and daylight saving time. The diffuse erythemal UV was considered for fixed lunch break times and fixed morning and afternoon break times. The cases considered were for groups of the population who are predominantly indoors and who spend their break times outdoors in shade. The biggest influence on the diffuse UV exposures of changing to daylight saving time is the timing of the outdoor meal and break times. The change causes a reduction in diffuse erythemal exposure for early or morning breaks and an increase in the diffuse erythemal exposure for late or afternoon breaks. Similarly, for the lunch break times, the changes in exposure are influenced by the timing of the break with respect to solar noon. Indoor workers who take their breaks outside in a shaded area may have a change in their exposure to diffuse UV due to a shift to daylight saving time, however the magnitude of this change and whether it is a positive or negative change in exposure will depend on the timing of the break. The increase in diffuse UV exposure due to the afternoon break may be negated by the decrease in exposure due to the morning break. In this case, the effect on diffuse UV exposures due to changing to daylight saving time will be minimal. PMID:18321724

Parisi, A V; Turner, J; Turnbull, D J; Schouten, P; Downs, N

2008-04-25

26

Flexible modeling of the cumulative effects of time-dependent exposures on the hazard.  

PubMed

Many epidemiological studies assess the effects of time-dependent exposures, where both the exposure status and its intensity vary over time. One example that attracts public attention concerns pharmacoepidemiological studies of the adverse effects of medications. The analysis of such studies poses challenges for modeling the impact of complex time-dependent drug exposure, especially given the uncertainty about the way effects cumulate over time and about the etiological relevance of doses taken in different time periods. We present a flexible method for modeling cumulative effects of time-varying exposures, weighted by recency, represented by time-dependent covariates in the Cox proportional hazards model. The function that assigns weights to doses taken in the past is estimated using cubic regression splines. We validated the method in simulations and applied it to re-assess the association between exposure to a psychotropic drug and fall-related injuries in the elderly. PMID:19708037

Sylvestre, Marie-Pierre; Abrahamowicz, Michal

2009-11-30

27

Pre-exposure chemoprophylaxis for HIV: It is time  

PubMed Central

The HIV-1 plague continues unabatedly across sub-Saharan Africa. In Botswana and Swaziland, nearly 40% of the entire adult population is already infected. No current program is capable of slowing the advancing tide. An effective vaccine and widespread treatment are years, if not, decades away. In this most urgent situation, I propose that pre-exposure chemoprophylaxis be studied as a means to reduce the spread of HIV-1 among at-risk individuals. PMID:15238164

Smith, Stephen M

2004-01-01

28

Effects of post exposure bake temperature and exposure time on SU-8 nanopattern obtained by electron beam lithography  

NASA Astrophysics Data System (ADS)

SU-8 is a photoresist imaged using UV rays. However, we investigated the characteristics of an SU-8 nanopattern obtained by electron beam lithography (EBL). In particular, we studied the relationship between post-exposure bake (PEB) temperature and exposure time on an SU-8 nanopattern with a focus on phase transition temperature. SU-8 residue was formed by increasing both PEB temperature and exposure time. To prevent the formation of this, Monte Carlo simulation was performed; the results of such simulation showed that decreasing the thickness of SU-8 can reduce the amount of residue from the SU-8 nanopattern. We confirmed that decreasing the thickness of SU-8 can also prevent the formation of residue from the SU-8 nanopattern with EBL.

Yasui, Manabu; Kazawa, Elito; Kaneko, Satoru; Takahashi, Ryo; Kurouchi, Masahito; Ozawa, Takeshi; Arai, Masahiro

2014-11-01

29

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

Microsoft Academic Search

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

Shuai Yuan; Anna Devor; David A. Boas; Andrew K. Dunn

2005-01-01

30

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

PubMed Central

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

Wodtke, Geoffrey T.

2013-01-01

31

The role of CO2 variability and exposure time for biological impacts of ocean acidification  

NASA Astrophysics Data System (ADS)

impacts of ocean acidification have mostly been studied using future levels of CO2 without consideration of natural variability or how this modulates both duration and magnitude of CO2 exposure. Here we combine results from laboratory studies on coral reef fish with diurnal in situ CO2 data from a shallow coral reef, to demonstrate how natural variability alters exposure times for marine organisms under increasingly high-CO2 conditions. Large in situ CO2 variability already results in exposure of coral reef fish to short-term CO2 levels higher than laboratory-derived critical CO2 levels (~600 µatm). However, we suggest that the in situ exposure time is presently insufficient to induce negative effects observed in laboratory studies. Our results suggest that both exposure time and the magnitude of CO2 levels will be important in determining the response of organisms to future ocean acidification, where both will increase markedly with future increases in CO2.

Shaw, Emily C.; Munday, Philip L.; McNeil, Ben I.

2013-09-01

32

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 ...

33

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

PubMed

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

Davies, Gemma; Whyatt, J Duncan

2014-07-01

34

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

NASA Technical Reports Server (NTRS)

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.

Borsky, P. N.

1980-01-01

35

Radiofrequency exposure in the French general population: band, time, location and activity variability.  

PubMed

Information on the exposure of individual persons to radiofrequency (RF) fields is scarce, although such data are crucial in order to develop a suitable exposure assessment method, and frame the hypothesis and design of future epidemiological studies. The main goal of this survey is to assess individual RF exposure on a population basis, while clarifying the relative contribution of different sources to the total exposure. A total of 377 randomly selected people were analyzed. Each participant was supplied with a personal exposure meter for 24-hour measurements (weekday), and kept a time-location-activity diary. Electric field strengths were recorded in 12 different RF bands every 13s. Summary statistics were calculated with the robust regression on order statistics method. Most of the time, recorded field strengths were not detectable with the exposure meter. Total field, cordless phones, WiFi-microwave, and FM transmitters stood apart with a proportion above the detection threshold of 46.6%, 17.2%, 14.1%, and 11.0%, respectively. The total field mean value was 0.201V/m, higher in urban areas, during daytime, among adults, and when moving. When focusing on specific channels, the highest mean exposure resulted from FM sources (0.044V/m), followed by WiFi-microwaves (0.038V/m), cordless phones (0.037V/m), and mobile phones (UMTS: 0.036V/m, UMTS: 0.037V/m). Various factors, however, contributed to a high variability in RF exposure assessment. These population-based estimates should therefore be confirmed by further surveys to better characterize the exposure situation in different microenvironments. PMID:19656570

Viel, Jean-François; Cardis, Elisabeth; Moissonnier, Monika; de Seze, René; Hours, Martine

2009-11-01

36

Statistical Properties of Longitudinal Time-Activity Data for Use in Human Exposure Modeling  

EPA Science Inventory

Understanding the longitudinal properties of the time spent in different locations and activities is important in characterizing human exposure to pollutants. The results of a four-season longitudinal time-activity diary study in eight working adults are presented, with the goal ...

37

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...

38

Optimizing electrical activation of porcine oocytes by adjusting pre- and post-activation mannitol exposure times.  

PubMed

Modifying electrical activation conditions have been used to improve in vitro embryo production and development in pigs. However, there is insufficient information about correlations of porcine embryo development with oocyte pre- and post-activation conditions. The purpose of this study was to compare the developmental rates of porcine oocytes subjected to different mannitol exposure times, either pre- or post-electrical activation, and to elucidate the reason for the optimal mannitol exposure time. Mannitol exposure times around activation were adjusted as 0, 1, 2 or 3 min. Blastocyst development were checked on day 7. Exposure of oocytes to mannitol for 1 or 2 min before electrical activation produced significantly higher blastocyst rates than exposure for 0 or 3 min. There was no significant difference in blastocyst rates when activated oocytes were exposed to mannitol for 0, 1, 2 or 3 min after electrical activation. While exposure of oocytes to mannitol for 1 min pre- and 3 min post-activation showed significantly higher blastocyst development than 0 min pre- and 0 min post-activation. It also showed higher maintenance of normal oocyte morphology than exposure for 0 min pre- and 0 min post-activation. In conclusion, exposure of oocytes to mannitol for 1 min pre- and 3 min post-activation seems to be optimal for producing higher in vitro blastocyst development of porcine parthenogenetic embryos. The higher blastocyst development is correlated with higher maintenance of normal morphology in oocytes exposed to mannitol for 1 min pre- and 3 min post-activation. PMID:25256295

Kwon, D; Saadeldin, Im; Kim, Sj; Park, Sj; Kang, Jt; Park, Hj; Moon, Jh; Koo, Oj; Jang, G; Lee, Bc

2014-12-01

39

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

SciTech Connect

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.

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

40

Highly time-variable exposure to chemicals--toward an assessment strategy.  

PubMed

Organisms in the environment experience fluctuating, pulsed, or intermittent exposure to pollutants. Accounting for effects of such exposures is an important challenge for environmental risk assessment, particularly given the simplified design of standard ecotoxicity tests. Dynamic simulation using toxicokinetic-toxicodynamic (TK-TD) models describes the processes that link exposure with effects in an organism and provides a basis for extrapolation to a range of exposure scenarios. In so doing, TK-TD modeling makes the risk assessment more robust and aids use and interpretation of experimental data. Toxicokinetic-toxicodynamic models are well-developed for predicting survival of individual organisms and are increasingly applied to sublethal endpoints. In the latter case particularly, linkage to individual-based models (IBMs) allows extrapolation to population level as well as accounting for differences in effects of toxicant exposure at different stages in the life cycle. Extrapolation between species remains an important constraint because there is currently no systematic understanding of species traits that cause differences in the relevant processes. Toxicokinetic-toxicodynamic models allow interrogation of exposure profiles to determine intrinsic toxicity potential rather than using absolute maximum concentrations or time-weighted averages as surrogates. A decision scheme is proposed to guide selection of risk assessment approaches using dose extrapolation based on Haber's Law, TK-TD models, and/or IBMs depending on the nature of toxic effect and timing in relation to life history. PMID:23564608

Ashauer, Roman; Brown, Colin D

2013-07-01

41

Application of real-time particle sensors to help mitigate exposures of wildland firefighters.  

PubMed

High particulate exposures have been demonstrated to decrease lung function among firefighters. In this article, the authors demonstrated the feasibility of using small real-time particle sensors to inform wildland firefighters so they may make informed decisions on the use of personal respiratory protection. Using 1 mg/m3 as an indicator point for use of appropriately designed respiratory protection, such sensors could help prevent 16% to 74% of particulate exposure during prescribed burns when firefighters assess exposure as low or medium. Adherence to such a guideline for the use of respiratory protection would involve its deployment during 3% to 22% of individual 8-hour shifts. In addition, data-logging sensors would provide a valuable tool for tracking exposure to particulates among wildland firefighters for occupational health monitoring. PMID:16961007

Edwards, Rufus; Johnson, Michael; Dunn, Kevin H; Naeher, Luke P

2005-01-01

42

Application of real-time particulate sensors to help mitigate exposures of wildland firefighters.  

SciTech Connect

High Particulate exposures have been demonstrated to decrease lung function among firefighters. In this article, the authors demonstrated the feasibility of using small real-time particle sensors to inform wildland firefighters so they can make informed decisions on the use of personal respiratory protection. Using 1mg/m3 as an indicator point for use of appropriately designed respiratory protection, such sensors could help prevent 16% to 74% of particulate exposure prescribed burns when firefighters assess exposure as low or medium. Adherence to such a guideline for the use of respiratory protection would involve its deployment of 3% to 22% of individual shifts. In addition, sensors are a valuable tool for tracking exposure to particulates among wildland firefighters for occupational health monitoring.

Edwards, Rufus; Johnson, Michael: Dunn, Kevin H.; Naeher, Luke P.

2005-02-01

43

Task- and time-dependent weighting factors in a retrospective exposure assessment of chemical laboratory workers.  

PubMed

A chemical exposure assessment was conducted for a cohort mortality study of 6157 chemical laboratory workers employed between 1943 and 1998 at four Department of Energy sites in Oak Ridge, Tennessee, and Aiken, South Carolina. Previous studies of chemical laboratory workers have included members within professional societies where exposure assessment was either limited or not feasible, or chemical processing employees where laboratory and production workers were combined. Because sufficient industrial hygiene records were unavailable for all four sites, weighted duration of employment was used as a surrogate for the magnitude of exposure. Potential exposure indices were calculated for each worker using number of days employed and weighting factors for frequency of contact and year of employment. A total of 591 unique laboratory job titles indicative of a chemical laboratory worker were collapsed into 18 general job title categories. Through discussions with current and retired workers, along with examination of historical organizational charts and job descriptions, the percentage of time with activities involving the direct handling of chemicals in the laboratory was estimated for each job title category. Scaled weighting factors of 1, 0.6, 0.3, and 0.05 were assigned to the job title categories representing 100%, 60%, 30%, and 5% of daily activities handling chemicals, respectively. Based on limited industrial hygiene monitoring data, personal radiation monitoring records, and professional judgment, weighting factors that declined 4% annually were applied to each year to account for improvements in laboratory technique, advancements in instrumentation, improvement in engineering controls, and increased safety awareness through time. The study cohort was separated into three categories of chemical exposures based on department level information: (1) inorganic, (2) mixed inorganic and organic, and (3) unknown. Potential exposure indices ranged from 0.15 to 6824.5 with a median value of 377.5 and a mean equal to 884.2. This exposure assessment method is useful for epidemiologic analyses when quantitative exposure data are absent or insufficient. PMID:17175512

Henn, Scott A; Utterback, David F; Waters, Kathleen M; Markey, Andrea M; Tankersley, William G

2007-02-01

44

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

Microsoft Academic Search

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 21000ngaiL?1) and exposure periods (1, 3, 7, 14

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

2011-01-01

45

Integration of image exposure time into a modified laser speckle imaging method  

PubMed Central

Speckle-based methods have been developed to characterize tissue blood flow and perfusion. One such method, called modified laser speckle imaging (mLSI), enables computation of blood flow maps with relatively high spatial resolution. Although it is known that the sensitivity and noise in LSI measurements depend on image exposure time, a fundamental disadvantage of mLSI is that it does not take into account this parameter. In this work, we integrate the exposure time into the mLSI method and provide experimental support of our approach with measurements from an in vitro flow phantom. PMID:21048287

Ramírez-San-Juan, J C; Huang, Y C; Salazar-Hermenegildo, N; Ramos-García, R; Muñoz-Lopez, J; Choi, B

2012-01-01

46

Effective denitrification at the groundwater surface-water interface: exposure rather than residence time  

NASA Astrophysics Data System (ADS)

Effective processing of material in aquatic systems, e. g. removal of nitrate upon denitrification, requires sufficient reaction time. This statement sounds trivial albeit its implication for biogeochemistry seems to be not fully recognized. The time teff required for effective processing of nitrate is controlled by the underlying biogeochemical rate law. In the simplest case of a 1st order reaction, teff is often calculated as the time when 63% of the initial concentration is consumed setting teff as 1/kreaction. It may, however, be more appropriate to derive teff,90%or teff,99% from the respective rate law. Hence a minimum time t > teff is required that exposes a specific biogeochemical process to conditions favourable for this process, which is anoxia in case of denitrification. This exposure time ?exp is not necessarily identical to the residence time ? of water in the particular system or flow path. Rather, the exposure time can be much shorter and may even fluctuate with time. As a consequence, Damköhler numbers (Da = ?exp/teff) for denitrification < 1 may be the consequence even though the age of water may be comparatively high. We therefore argue that the key for understanding denitrification efficiency at the groundwater surface-water interface (or in groundwater systems in general) is the quantification of the exposure time. This contribution therefore aims i) to estimate exposure times required for effective denitrification based on an analysis of rate constants for denitrification, ii) to relate these time scales to typical residence time distributions found at the groundwater surface-water interface and iii) to discuss implications for denitrification efficiencies. References: Oldham, C; Farrow, DE; Peiffer, S (2013): A generalized Damköhler number for classifying material processing in hydrological systems, Hydrology and Earth System Sciences, 17, 1133-1148 Frei, S; Knorr, KH; Peiffer, S; Fleckenstein, J (2012): Surface micro-topography causes hot spots of biogeochemical activity in wetland systems - a virtual modeling experiment., Journal of Geophysical Research - Biogeosciences, 117(G00N12), 1 - 18

Peiffer, Stefan; Frei, Sven

2014-05-01

47

Safety of endoscopic retrograde cholangiopancreatography in pregnancy: Fluoroscopy time and fetal exposure, does it matter?  

PubMed Central

AIM: To estimate the fetal radiation exposure using thermoluminescent dosimeters (TLD’s) in pregnant patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) and assess its relevance. METHODS: Data on thirty-five therapeutic ERCPs conducted in pregnant patients from 2001 to 2009 were retrieved from a prospective database. Techniques to minimize fluoroscopy time were implemented and the fluoroscopy times captured. TLD’s were placed on the mother to estimate the fetal radiation exposure and the results were compared to the maximum allowed dose of radiation to the fetus [0.005 gray (Gy)]. Obstetrics consultations were obtained and the fetus was monitored before and after the ERCP. Fluoroscopy was performed at 75 kVp. ERCP was performed with the patients supine by dedicated biliary endoscopists performing more than 500 cases a year. RESULTS: A total of 35 pregnant patients underwent ERCP and biliary sphincterotomy (14 in first trimester, 11 in second trimester, and 10 in third trimester). Mean maternal age was 25 years (range 16-37 years) and mean gestational age was 18.9 wk (range 4-35 wk). Mean fluoroscopy time was 0.15 min (range 0-1 min). For 23 women, the estimated fetal radiation exposure was almost negligible (< 0.0001 Gy) while for 8 women, it was within the 0.0001-0.0002 Gy range. Three women had an estimated fetal radiation exposure between 0.0002 and 0.0005 Gy and 1 woman had an estimated fetal radiation exposure greater than 0.0005 Gy. Complications included 2 post-sphincterotomy bleeds, 2 post-ERCP pancreatitis, and 1 fatal acute respiratory distress syndrome. One patient developed cholecystitis 2 d after ERCP. CONCLUSION: ERCP with modified techniques is safe during pregnancy, and estimating the fetal radiation exposure from the fluoroscopy time or measuring it via TLD’s is unnecessary. PMID:23596536

Smith, Ioana; Gaidhane, Monica; Goode, Allen; Kahaleh, Michel

2013-01-01

48

Physiological Changes in Skin Barrier Function in Relation to Occlusion Level, Exposure Time and Climatic Conditions  

Microsoft Academic Search

Skin occlusion is a condition encountered with various articles as part of everyday life and resulting changes in skin barrier physiology often remain unnoticed. In the present study we aimed to understand the impact of absorbent feminine hygiene articles, one vapor-permeable and one vapor-impermeable, on skin hydration in response to exposure time and different environmental climatic conditions. Using a forearm

P. Schäfer; C. Bewick-Sonntag; M. G. Capri; E. Berardesca

2002-01-01

49

Observational Cadence vs. Exposure Time Trade-off for Supernova Surveys  

Microsoft Academic Search

To extract the maximum cosmological information from type Ia supernovae, magnitude measurement errors should not exceed the intrinsic dispersion of 0.15 magnitudes. This requirement has a direct impact on any supernova cosmology mission design. We explore the observational cadence (how frequently the supernova flux is sampled -the light curve), the exposure time per sampling, and trade-offs between these two parameters

Natalia Kuznetsova

2006-01-01

50

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

E-print Network

V8P 5C2, Canada The ecological impact of parasite transmission from fish farms is probably mediated�louse population dynamics, and should therefore be accommodated in coastal planning and management where fish farmsSea lice and salmon population dynamics: effects of exposure time for migratory fish Martin Krkosek

Lewis, Mark

51

Coincident Timing Behavior of Young Mentally Retarded Workers under Varying Conditions of Target Velocity and Exposure.  

ERIC Educational Resources Information Center

The degree to which response complexity affects the ability of moderately mentally retarded adults to perform on a coincident timing task was examined in two experiments. Analyses of both constant and variable error scores suggested that an optimal exposure distance for the task existed. (Author)

Wade, Michael G.; And Others

1982-01-01

52

INFLUENCE OF TIME OF EXPOSURE TO CARBON TETRACHLORIDE ON TOXIC LIVER INJURY  

EPA Science Inventory

The study was conducted to determine whether, and by what mechanisms, time of exposure could influence the ability of a model hepatotoxin, carbon tetrachloride (CCl4) to cause liver injury. Rats dosed orally with CCl4 during their active/dark cycle were found to be more susceptib...

53

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

E-print Network

exposure. In laser-heating tests, response times varied from tenths of microseconds to several achieve submicrosecond responses, but extreme film thinness (less than 100 nm) affects sensitiv- ity. fabricated SMTCs by first electrodepositing silver wires 1.0 to 0.5 m in diameter onto half of a stepped

Odom, Teri W.

54

A Real-Time Exposure System for Electrophysiological Recording in Brain Slices  

Microsoft Academic Search

In order to study possible effects of microwave electromagnetic (EM) fields on neuronal activity, a real-time exposure system was designed and fabricated. The structure is suitable for electrophysiological recording in brain slices, a widely used in vitro methodology for investigations on neuronal function. The EM features of the structure were characterized both numerically and experimentally. Results indicate that the system

Alessandra Paffi; Monica Pellegrino; Romeo Beccherelli; Francesca Apollonio; Micaela Liberti; Daniela Platano; Giorgio Aicardi; Guglielmo D'Inzeo

2007-01-01

55

First experiences with a high sensitive videocamera with internal multiframe exposure time  

NASA Astrophysics Data System (ADS)

This is a short report about the use of the high sensitive black-white video camera MTV-12V1-EX that allows to increase the sensitivity about 2 magnitudes in normal video mode and about 4 magnitudes by using the internal selectable multiframe exposure time with 0.3 sec time resolution (compared with sensitivity of simple black-white video cameras). A video record demonstrates some occultation events and starfields.

Rothe, Wolfgang

2002-07-01

56

Ecological relevance and sensitivity depending on the exposure time for two biomarkers.  

PubMed

Biomarkers are widely used to assess pesticide stress, but their ecological relevance and exposure time dependent sensitivity is still heavily debated. We studied both aspects in larvae of the damselfly Coenagrion puella, comparing the impact of low doses of atrazine, carbaryl, and endosulfan on two key biomarkers (acetylcholinesterase [AChE] activity and fluctuating asymmetry [FA]) and their relationship with life history traits (mortality, development time, growth rate, and body size). Larvae exposed to the pesticides had, in general, longer development times. Size, growth rate, and mortality were not affected by any of the pesticides. In the long-term exposure, AChE activity was diminished by atrazine treatments and stimulated by carbaryl treatments, and was not affected in the endosulfan treatments. FA decreased with increasing endosulfan concentrations and showed no reaction to atrazine or carbaryl. Overall, short-term exposure tended to overestimate the results of long-term exposure decreasing growth rates and enhancing inhibition of AChE activity in atrazine and carbaryl treatments. In line with its ecological relevance, relationship between biomarkers and life history traits showed that AChE inhibition was positively correlated with mortality, while FA was traded off with size. These results show that caution should be exerted when using these biomarkers to assess pesticide pollution in field situations. PMID:18000848

Campero, Melina; Ollevier, Frans; Stoks, Robby

2007-12-01

57

Personal exposure to ultrafine particles: the influence of time-activity patterns.  

PubMed

Exposure to ultrafine particles (UFPs) is deemed to be a major risk affecting human health. Therefore, airborne particle studies were performed in the recent years to evaluate the most critical micro-environments, as well as identifying the main UFP sources. Nonetheless, in order to properly evaluate the UFP exposure, personal monitoring is required as the only way to relate particle exposure levels to the activities performed and micro-environments visited. To this purpose, in the present work, the results of experimental analysis aimed at showing the effect of the time-activity patterns on UFP personal exposure are reported. In particular, 24 non-smoking couples (12 during winter and summer time, respectively), comprised of a man who worked full-time and a woman who was a homemaker, were analyzed using personal particle counter and GPS monitors. Each couple was investigated for a 48-h period, during which they also filled out a diary reporting the daily activities performed. Time activity patterns, particle number concentration exposure and the related dose received by the participants, in terms of particle alveolar-deposited surface area, were measured. The average exposure to particle number concentration was higher for women during both summer and winter (Summer: women 1.8 × 10(4) part. cm(-3); men 9.2 × 10(3) part. cm(-3); Winter: women 2.9 × 10(4) part. cm(-3); men 1.3 × 10(4) part. cm(-3)), which was likely due to the time spent undertaking cooking activities. Staying indoors after cooking also led to higher alveolar-deposited surface area dose for both women and men during the winter time (9.12 × 10(2) and 6.33 × 10(2) mm(2), respectively), when indoor ventilation was greatly reduced. The effect of cooking activities was also detected in terms of women's dose intensity (dose per unit time), being 8.6 and 6.6 in winter and summer, respectively. On the contrary, the highest dose intensity activity for men was time spent using transportation (2.8 in both winter and summer). PMID:24080417

Buonanno, G; Stabile, L; Morawska, L

2014-01-15

58

Polychlorinated biphenyl (PCB) exposure in mothers and time to pregnancy in daughters  

PubMed Central

Developmental exposure to polychlorinated biphenyls (PCBs) disrupts reproduction in animals. Human data are lacking. We measured PCBs in preserved mothers' serum samples collected during 1960-1963, 1-3 days after their daughters' birth. We recorded time to pregnancy (TTP) in 289 daughters 28-31 years later. PCB congeners 187, 156, and 99 in mother's serum were associated with longer TTP in their daughters while PCB congeners 105,138 and 183 were associated shorter TTP. Probability of pregnancy fell by 38% (95% CI 17%-53%) and infertility was higher (30% not pregnant after 13 cycles vs.11% not pregnant after 13 cycles) among women whose mothers had a higher proportion of PCB congeners associated with longer TTP (75th percentile versus 25th percentile).This study demonstrates, for the first time, that developmental exposure to PCBs may disrupt pregnancy in humans. PMID:21296657

Cohn, Barbara A.; Cirillo, Piera M.; Sholtz, Robert I.; Ferrara, Assiamira; Park, June-Soo; Schwingl, Pamela J.

2011-01-01

59

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

NASA Technical Reports Server (NTRS)

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.

Brown, V. J.

1975-01-01

60

Lysis of Chlamydomonas reinhardtii by high-intensity focused ultrasound as a function of exposure time.  

PubMed

Efficient lysis of microalgae for lipid extraction is an important concern when processing biofuels. Historically, ultrasound frequencies in the range of 10-40 kHz have been utilized for this task. However, greater efficiencies might be achievable if higher frequencies could be used. In our study, we evaluated the potential of using 1.1 MHz ultrasound to lyse microalgae for biofuel production while using Chlamydomonas reinhardtii as a model organism. The ultrasound was generated using a spherically focused transducer with a focal length of 6.34 cm and an active diameter of 6.36 cm driven by 20 cycle sine-wave tone bursts at a pulse repetition frequency of 2 kHz (3.6% duty cycle). The time-average acoustic power output was 26.2 W while the spatial-peak-pulse-average intensity (ISPPA) for each tone burst was 41 kW/cm(2). The peak compressional and rarefactional pressures at the focus were 102 and 17 MPa, respectively. The exposure time was varied for the different cases in the experiments from 5s to 9 min and cell lysis was assessed by quantifying the percentage of protein and chlorophyll release into the supernate as well as the lipid extractability. Free radical generation and lipid oxidation for the different ultrasound exposures were also determined. We found that there was a statistically significant increase in lipid extractability for all of the exposures compared to the control. The longer exposures also completely fragmented the cells releasing almost all of the protein and chlorophyll into the supernate. The cavitation activity did not significantly increase lipid oxidation while there was a minor trend of increased free radical production with increased ultrasound exposure. PMID:24355286

Bigelow, Timothy A; Xu, Jin; Stessman, Dan J; Yao, Linxing; Spalding, Martin H; Wang, Tong

2014-05-01

61

Investigation of palladium alloy properties degradation during long-time tritium exposure  

Microsoft Academic Search

The investigation of life-time properties of Russian industrial Pd-membrane alloy V-1, as a material for a palladium diffuser of the ITER Fuel Clean-Up System, has been continued. The saturation experiment with duration up to 2004 h has been performed. The calculated helium-3 concentration in the samples was 466 appm. Investigation of the samples after exposure showed that mechanical properties were

V. Tebus; L Rivkis; G Arutunova; E Dmitrievsky; V Filin; Y Golikov; V Krivova; V Kapychev

1999-01-01

62

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

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

63

Exposure to chemical cocktails before or after conception - The effect of timing on ovarian development?  

PubMed Central

Exposure of female fetuses to environmental chemicals (ECs) during pregnancy results in a disturbed ovarian adult phenotype. We investigated the influence of pre- and/or post-conception exposure to low-level mixtures of ECs on the structure and function of the fetal ovine ovary. We examined ovarian morphology, expression of oocyte and granulosa cell-specific genes and proteome. Female fetuses were collected at day 110 of gestation, from dams exposed continuously until, and after mating, by grazing in pastures treated with sewage sludge as a fertiliser (TT) or in control fields treated with inorganic fertiliser (CC). In addition, in a cross-over design, fetal ovaries were collected from dams maintained on sludge pastures up to the time of mating but then transferred to control pastures (TC) and, reciprocally, those transferred from control to treated pastures at mating (CT). On examination, the proportion of type 1a follicles (activating primordial follicles) was significantly lower in animals from the CT groups compared with CC and TT groups (P < 0.05). Of the 23 ovarian gene transcripts studied, 14 were altered in the ovaries of exposed fetuses (CT, TC, and TT) relative to controls, with the largest number of changes observed in cross-exposure pattern groups (CT or TC). Continuous EC exposure (TT) produced fewer transcript alterations and only two genes (INHBA and GSN) presented differential profiles between CC and TT. Fetal ovarian proteome analysis (2-DE gels) showed, across all exposure groups, 86 differentially expressed protein spots compared to controls. Animals in the CT group exhibited the highest number (53) while TC and TT presented the same number of affected protein spots (42). Fetal ovarian proteins with altered expression included MVP (major vault protein) and several members of the heat-shock family (HSPA4L, HSP90AA1 and HSF1). The present findings indicate that continuous maternal EC exposure before and during gestation, are less deleterious for fetal ovarian development than a change in maternal EC exposure between pre and post-conception. The pathways by which the ovary responds to this chemical stress were common in TT, CT, TC exposed foetuses. In addition to the period of pregnancy, the pre-conception period appears also as crucial for conditioning long-term effects of EC exposure on ovarian development and primordial follicle reserve and hence future fertility. PMID:23791816

Bellingham, Michelle; Amezaga, Maria R.; Mandon-Pepin, Beatrice; Speers, Christopher J.B.; Kyle, Carol E.; Evans, Neil P.; Sharpe, Richard M.; Cotinot, Corinne; Rhind, Stewart M.; Fowler, Paul A.

2013-01-01

64

Histological and cytological examination of rat reproductive tissue after short-time intermittent radiofrequency exposure.  

PubMed

The unfavourable outcomes of mobile phone use on male fertility have still not been fully elaborated. To establish the potentially adverse effects of everyday exposure to radiofrequency radiation (RF) on humans, we performed a controlled animal study that aimed to investigate the influence of RF radiation on rat testis histology as well as the amount, mobility, and structure of epididymal free sperm cell population. Eighteen adult male rats were divided into two groups of nine. One group comprised sham-exposed control animals, while the other group endured total body irradiation for an hour daily during two weeks. A 915 MHz RF field, power density of 2.4 W m(-2) and strength of 30 V m(-1) was generated in a Gigahertz Transversal Electromagnetic chamber. The specific absorption rate (SAR) was 0.6 W kg(-1). Body mass and temperature were measured before and after each exposure treatment. Immediately after the last exposure, the animals were sacrificed and testes removed and prepared for histological analysis. The free sperm cells were collected from the cauda epididymis and their quantity, quality, and morphology were microscopically determined using a haemocytometer. No statistically significant alteration in any of the endpoints was observed. This study found no evidence of an unfavourable effect of the applied RF radiation on testicular function or structure. Based on these results, we can conclude that short-time intermittent exposure to RF radiation does not represent a significant risk factor for rat reproductive functions. PMID:24384757

Troši?, Ivan?ica; Matauši?-Pišl, Mirjana; Pavi?i?, Ivan; Marjanovi?, Ana Marija

2013-12-01

65

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

PubMed Central

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

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

2014-01-01

66

Complexities of sibling analysis when exposures and outcomes change with time and birth order.  

PubMed

In this study, we demonstrate the complexities of performing a sibling analysis with a re-examination of associations between cell phone exposures and behavioral problems observed previously in the Danish National Birth Cohort. Children (52,680; including 5441 siblings) followed up to age 7 were included. We examined differences in exposures and behavioral problems between siblings and non-siblings and by birth order and birth year. We estimated associations between cell phone exposures and behavioral problems while accounting for the random family effect among siblings. The association of behavioral problems with both prenatal and postnatal exposure differed between siblings (odds ratio (OR): 1.07; 95% confidence interval (CI): 0.69-1.66) and non-siblings (OR: 1.54; 95% CI: 1.36-1.74) and within siblings by birth order; the association was strongest for first-born siblings (OR: 1.72; 95% CI: 0.86-3.42) and negative for later-born siblings (OR: 0.63; 95% CI: 0.31-1.25), which may be because of increases in cell phone use with later birth year. Sibling analysis can be a powerful tool for (partially) accounting for confounding by invariant unmeasured within-family factors, but it cannot account for uncontrolled confounding by varying family-level factors, such as those that vary with time and birth order. PMID:24064530

Sudan, Madhuri; Kheifets, Leeka I; Arah, Onyebuchi A; Divan, Hozefa A; Olsen, Jørn

2014-01-01

67

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

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

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

68

Different effects of PM 10 exposure on preterm birth by gestational period estimated from time-dependent survival analyses  

Microsoft Academic Search

Purpose  We conducted this study to determine if the preterm risks due to PM10 exposure vary with the exposure periods during pregnancy. This study was also conducted to estimate the different effects\\u000a of PM10 exposure on preterm birth by exposure periods using the extended Cox model with PM10 exposure as a time-dependent covariate.\\u000a \\u000a \\u000a \\u000a Methods  We studied birth data obtained from the Korea

Young Ju Suh; Ho Kim; Ju Hee Seo; Hyesook Park; Young Ju Kim; Yun Chul Hong; Eun Hee Ha

2009-01-01

69

Permethrin exposure from fabric-treated military uniforms under different wear-time scenarios.  

PubMed

The objective of the project was to ascertain whether urinary biomarkers of permethrin exposure are detected after wearing post-tailored, fabric-treated military uniforms under two different wear-time exposure scenarios. Study A occurred over 3.5 days and involved six participants wearing treated uniforms continuously for 30-32?h. Urine collection occurred at scheduled time points before, during, and after wearing the uniform. Study B, conducted over 19 days, included 11 participants wearing treated uniforms for 3 consecutive days, 8?h each day (with urine collection before, during, and after wear). Urinary biomarkers of permethrin (3-phenoxybenzoic acid (3PBA), cis- 2,2-(dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cDCCA), trans- 2,2-(dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (tDCCA)) were detected during and after wear. Biomarker detection generally occurred over the 10- to 12-h period after putting on the uniform and subsided 24?h following uniform removal (in both Study A and B scenarios). Those wearing permethrin-treated uniforms under the longer wear-time scenario (Study A) excreted significantly higher cumulative mean levels compared with those in Study B (3.29 times higher for 3PBA and 2.23 times higher for the sum of c/tDCCA (P?0.001)). Findings suggest that wearing permethrin-treated clothing does increase absorbed, internal dose levels of permethrin above population levels and is significantly related to wear-time duration. PMID:24104061

Proctor, Susan P; Maule, Alexis L; Heaton, Kristin J; Adam, Gina E

2014-11-01

70

Toxicokinetics of the flame retardant hexabromocyclododecane alpha: effect of dose, timing, route, repeated exposure, and metabolism.  

PubMed

Alpha-hexabromocyclododecane (?-HBCD) is an emerging persistent organic pollutant present in the hexabromocyclododecane (HBCD) commercial mixture. HBCD is used as an additive flame retardant in a wide variety of household consumer products. Three main stereoisomers, alpha (?), beta (?), and gamma (?), comprise roughly 10, 10, and 80% of the mixture, respectively. Despite its small contribution to HBCD global production and usage, ?-HBCD is the major stereoisomer found in wildlife and human tissues including breast milk and blood in North America, European Union, and Asia. No mammalian or human data are currently available regarding the toxicokinetics of ?-HBCD. This study was conducted in an effort to fully characterize the absorption, distribution, metabolism, and elimination of ?-HBCD following a single and repeated exposure with respect to dose, time, and route of administration in female C57BL/6 mice. Results indicate that ?90% of the administered dose (3 mg/kg) was absorbed after oral exposure. Disposition was (1) dictated by lipophilicity, as adipose, liver, muscle, and skin were major depots and (2) was dose dependent with nonlinear accumulation at higher doses. Elimination, both whole-body and from individual tissues, was biphasic. ?-HBCD-derived radioactivity was excreted in the feces as parent and metabolites, whereas urine only contained metabolites. Presence of polar metabolites in the blood and urine were a major factor in determining the rapid initial whole-body half-life after a single oral exposure. Initial half-lives were ?1-3 days and much longer terminal half-lives of 17 days were observed, suggesting the potential for ?-HBCD bioaccumulation. A 10-day repeated study supports ?-HBCD bioaccumulation potential. Stereoisomerization previously observed after exposure to ?-HBCD was not seen after exposure of ?-HBCD. The toxicokinetic behavior reported here has important implications for the extrapolation of toxicological studies of the commercial HBCD mixture to the assessment of risk of ?-HBCD which is the major stereoisomer found in wildlife and people. PMID:21441408

Szabo, David Taylor; Diliberto, Janet J; Hakk, Heldur; Huwe, Janice K; Birnbaum, Linda S

2011-06-01

71

Physiological changes in skin barrier function in relation to occlusion level, exposure time and climatic conditions.  

PubMed

Skin occlusion is a condition encountered with various articles as part of everyday life and resulting changes in skin barrier physiology often remain unnoticed. In the present study we aimed to understand the impact of absorbent feminine hygiene articles, one vapor-permeable and one vapor-impermeable, on skin hydration in response to exposure time and different environmental climatic conditions. Using a forearm model, volunteers were patched with moistened vapor-permeable and -impermeable articles in parallel for 1, 3, and 6 h and under different climatic conditions (i.e. 20 degrees C/30% relative humidity, 25 degrees C/50% relative humidity, 30 degrees C/ 75% relative humidity). The physiological changes in the skin barrier function were measured via skin hydration, evaporation of superficial water (skin surface water loss, SSWL) and relative humidity in the microclimate between skin and occlusive article (RH(mc)). The results show that skin hydration, SSWL, and RH(mc) under a vapor-permeable article are reduced versus the vapor-impermeable article for all exposure times at 25 degrees C and 50% relative humidity. SSWL and RH(mc) decrease from their 1-hour peak values with increasing exposure time, while skin hydration decreases only after 3 h of exposure. Lower environmental temperature (20 degrees C) and lower relative humidity (30%) have little impact on the reduction of SSWL and RH(mc,) but more so on the reduction of skin hydration. Higher temperature (30 degrees C) and higher relative humidity (75%) increase RH(mc) and skin hydration under both vapor-permeable and -impermeable articles while SSWL is reduced under the vapor-impermeable article under these conditions. In conclusion, vapor-permeability is the key factor for physiological changes in the barrier function of the skin under occlusion, exposure time and climatic conditions being modulating factors. These findings have been integrated into a model of skin hydration under occlusion in the context of absorbent hygiene articles. While current vapor-impermeable articles are effective in reducing the excessive moisture on the skin due to bodily discharge, vapor permeability adds a further measurable benefit in reducing skin overhydration. PMID:11803253

Schäfer, P; Bewick-Sonntag, C; Capri, M G; Berardesca, E

2002-01-01

72

Real-Time Aircraft Cosmic Ray Radiation Exposure Predictions from the NAIRAS Model  

NASA Astrophysics Data System (ADS)

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a prototype operational model for predicting commercial aircraft radiation exposure from galactic and solar cosmic rays. NAIRAS predictions are currently streaming live from the project's public website, and the exposure rate nowcast is also available on the SpaceWx smartphone app for iPhone, IPad, and Android. Cosmic rays are the primary source of human exposure to high linear energy transfer radiation at aircraft altitudes, which increases the risk of cancer and other adverse health effects. Thus, the NAIRAS model addresses an important national need with broad societal, public health and economic benefits. There is also interest in extending NAIRAS to the LEO environment to address radiation hazard issues for the emerging commercial spaceflight industry. The processes responsible for the variability in the solar wind, interplanetary magnetic field, solar energetic particle spectrum, and the dynamical response of the magnetosphere to these space environment inputs, strongly influence the composition and energy distribution of the atmospheric ionizing radiation field. Real-time observations are required at a variety of locations within the geospace environment. The NAIRAS model is driven by real-time input data from ground-, atmospheric-, and space-based platforms. During the development of the NAIRAS model, new science questions and observational data gaps were identified that must be addressed in order to obtain a more reliable and robust operational model of atmospheric radiation exposure. The focus of this talk is to present the current capabilities of the NAIRAS model, discuss future developments in aviation radiation modeling and instrumentation, and propose strategies and methodologies of bridging known gaps in current modeling and observational capabilities.

Mertens, C. J.; Tobiska, W.; Kress, B. T.; Xu, X.

2012-12-01

73

Wearable real-time direct reading naphthalene and VOC personal exposure monitor  

NASA Astrophysics Data System (ADS)

Naphthalene has been identified by the National Research Council as a serious health hazard for personnel working with jet fuels and oil-based sealants containing naphthalene. We are developing a family of miniature, self-contained, direct reading personal exposure monitors (PEMs) to detect, differentiate, quantify, and log naphthalene and other volatile organic compounds (VOCs) in the breathing zone of the wearer or in the hands of an industrial hygienist with limits of detection in the low parts per billion (ppb) range. The VOC Dosimeter (VOCDos) described here is a PEM that provides real-time detection and data logging of exposure as well as accumulated dose, with alarms addressing long term and immediate exposure limits. We will describe the sensor, which employs optical methods with a unique excitation source and rapidly refreshable vapor concentrator. This paper addresses the rapidly increasing awareness of the health risks of inhaling jet fuel vapors by Department of Defense (DOD) personnel engaged in or around jet fueling operations. Naphthalene is a one to three percent component of the 5 billion gallons of jet fuels used annually by DOD. Naphthalene is also a component of many other petroleum products such as asphalt and other oil-based sealants. The DOD is the single largest user of petroleum fuels in the United States (20% of all petroleum fuel used). The VOCDos wearable sensor provides real-time detection and data logging of exposure as well as accumulated dose. We will describe the sensor, which employs endogenous fluorescence from VOCs accumulated on a unique, rapidly refreshable, patent-pending concentrator, excited by a unique deep ultraviolet excitation source.

Hug, W. F.; Bhartia, R.; Reid, R. D.; Reid, M. R.; Oswal, P.; Lane, A. L.; Sijapati, K.; Sullivan, K.; Hulla, J. E.; Snawder, J.; Proctor, S. P.

2012-06-01

74

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

PubMed

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

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

2009-01-01

75

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

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

76

Neurodevelopmental alcohol exposure elicits long-term changes to gene expression that alter distinct molecular pathways dependent on timing of exposure  

PubMed Central

Background Maternal alcohol consumption is known to adversely affect fetal neurodevelopment. While it is known that alcohol dose and timing play a role in the cognitive and behavioral changes associated with prenatal alcohol exposure, it is unclear what developmental processes are disrupted that may lead to these phenotypes. Methods Mice (n=6 per treatment per developmental time) were exposed to two acute doses of alcohol (5 g/kg) at neurodevelopmental times representing the human first, second, or third trimester equivalent. Mice were reared to adulthood and changes to their adult brain transcriptome were assessed using expression arrays. These were then categorized based on Gene Ontology annotations, canonical pathway associations, and relationships to interacting molecules. Results The results suggest that ethanol disrupts biological processes that are actively occurring at the time of exposure. These include cell proliferation during trimester one, cell migration and differentiation during trimester two, and cellular communication and neurotransmission during trimester three. Further, although ethanol altered a distinct set of genes depending on developmental timing, many of these show interrelatedness and can be associated with one another via ‘hub’ molecules and pathways such as those related to huntingtin and brain-derived neurotrophic factor. Conclusions These changes to brain gene expression represent a ‘molecular footprint’ of neurodevelopmental alcohol exposure that is long-lasting and correlates with active processes disrupted at the time of exposure. This study provides further support that there is no neurodevelopmental time when alcohol cannot adversely affect the developing brain. PMID:23497526

2013-01-01

77

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

PubMed

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. This research investigates changes in time allocations and exposures that result from traffic congestion. Time shifts were derived using data from the National Human Activity Pattern Survey (NHAPS), which was aggregated to nine microenvironments (six indoor locations, two outdoor locations and one transport location). After imputing missing values, handling outliers, and conducting other quality checks, these data were stratified by respondent age, employment status and period (weekday/weekend). Trade-offs or time-shift coefficients between time spent in vehicles and the eight other microenvironments were then estimated using robust regression. For children and retirees, congestion primarily reduced the time spent at home; for older children and working adults, congestion shifted the time spent at home as well as time in schools, public buildings, and other indoor environments. Changes in benzene and PM(2.5) exposure were estimated for the current average travel delay in the U.S. (9 min day(-1)) and other scenarios using the estimated time shifts coefficients, concentrations in key microenvironments derived from the literature, and a probabilistic analysis. Changes in exposures depended on the duration of the congestion and the pollutant. For example, a 30 min day(-1) travel delay was determined to account for 21+/-12% of current exposure to benzene and 14+/-8% of PM(2.5) exposure. The time allocation shifts and the dynamic approach to TAPs improve estimates of exposure impacts from congestion and other recurring events. PMID:19683333

Zhang, Kai; Batterman, Stuart A

2009-10-15

78

Gender differences in road traffic injury rate using time travelled as a measure of exposure.  

PubMed

There is no consensus on whether the risk of road traffic injury is higher among men or among women. Comparison between studies is difficult mainly due to the different exposure measures used to estimate the risk. The measures of exposure to the risk of road traffic injury should be people's mobility measures, but frequently authors use other measures such population or vehicles mobility. We compare road traffic injury risk in men and women, by age, mode of transport and severity, using the time people spend travelling as the exposure measure, in Catalonia for the period 2004-2008. This is a cross-sectional study including all residents aged over 3 years. The road traffic injury rate was calculated using the number of people injured, from the Register of Accidents and Victims of the National Traffic Authority as numerator, and the person-hours travelled, from the 2006 Daily Mobility Survey carried out by the Catalan regional government, as denominator. Sex and age specific rates by mode of transport and severity were calculated, and Poisson regression models were fitted. Among child pedestrians and young drivers, males present higher risk of slight and severe injury, and in the oldest groups women present higher risk. The death rate is always higher in men. There exists interaction between sex and age in road traffic injury risk. Therefore, injury risk is higher among men in some age groups, and among women in other groups, but these age groups vary depending on mode of transport and severity. PMID:24384384

Santamariña-Rubio, Elena; Pérez, Katherine; Olabarria, Marta; Novoa, Ana M

2014-04-01

79

Space Weathering Effects in Lunar Soils: The Roles of Surface Exposure Time and Bulk Chemical Composition  

NASA Technical Reports Server (NTRS)

Space weathering effects on lunar soil grains result from both radiation-damaged and deposited layers on grain surfaces. Typically, solar wind irradiation forms an amorphous layer on regolith silicate grains, and induces the formation of surficial metallic Fe in Fe-bearing minerals [1,2]. Impacts into the lunar regolith generate high temperature melts and vapor. The vapor component is largely deposited on the surfaces of lunar soil grains [3] as is a fraction of the melt [4, this work]. Both the vapor-deposits and the deposited melt typically contain nanophase Fe metal particles (npFe0) as abundant inclusions. The development of these rims and the abundance of the npFe0 in lunar regolith, and thus the optical properties, vary with the soil mineralogy and the length of time the soil grains have been exposed to space weathering effects [5]. In this study, we used the density of solar flare particle tracks in soil grains to estimate exposure times for individual grains and then perform nanometer-scale characterization of the rims using transmission electron microscopy (TEM). The work involved study of lunar soil samples with different mineralogy (mare vs. highland) and different exposure times (mature vs. immature).

Zhang, Shouliang; Keller, Lindsay P.

2011-01-01

80

Bayesian modelling of daphnid responses to time-varying cadmium exposure in laboratory aquatic microcosms.  

PubMed

Experiments were carried out to test the effects of cadmium on five aquatic species in 2-L indoor freshwater/sediment microcosms. Experimental data were collected over 21 days in static conditions, i.e. the microcosms evolved without water renewal. Because of speciation, the total cadmium concentration in water decreased with time. Here we present a focus on Daphnia magna responses. For the three life history traits we considered (survival, growth and reproduction), mathematical effect models were built based on threshold stress functions involving no effect concentrations (NECs). These models took the time-varying conditions of exposure into account through a time-recurrent formalism. Within a Bayesian framework, four kinds of data were fitted simultaneously (exposure, survival, growth and reproduction), using an appropriate error model for each endpoint. Hence, NECs were determined as well as their associated estimation uncertainty. Through this modelling approach, we demonstrate that thresholds for stress functions can be successfully inferred even in experimental setup more complex than standard bioassays. PMID:21056469

Billoir, Elise; Delhaye, Hélène; Clément, Bernard; Delignette-Muller, Marie Laure; Charles, Sandrine

2011-05-01

81

Gene Expression-Based Dosimetry by Dose and Time in Mice Following Acute Radiation Exposure  

PubMed Central

Rapid and reliable methods for performing biological dosimetry are of paramount importance in the event of a large-scale nuclear event. Traditional dosimetry approaches lack the requisite rapid assessment capability, ease of use, portability and low cost, which are factors needed for triaging a large number of victims. Here we describe the results of experiments in which mice were acutely exposed to 60Co gamma rays at doses of 0 (control) to 10 Gy. Blood was obtained from irradiated mice 0.5, 1, 2, 3, 5, and 7 days after exposure. mRNA expression levels of 106 selected genes were obtained by reverse-transcription real time PCR. Stepwise regression of dose received against individual gene transcript expression levels provided optimal dosimetry at each time point. The results indicate that only 4–7 different gene transcripts are needed to explain ? 0.69 of the variance (R2), and that receiver-operator characteristics, a measure of sensitivity and specificity, of ? 0.93 for these statistical models were achieved at each time point. These models provide an excellent description of the relationship between the actual and predicted doses up to 6 Gy. At doses of 8 and 10 Gy there appears to be saturation of the radiation-response signals with a corresponding diminution of accuracy. These results suggest that similar analyses in humans may be advantageous for use in a field-portable device designed to assess exposures in mass casualty situations. PMID:24358280

Tucker, James D.; Divine, George W.; Grever, William E.; Thomas, Robert A.; Joiner, Michael C.; Smolinski, Joseph M.; Auner, Gregory W.

2013-01-01

82

Sociality and sickness: have cytokines evolved to serve social functions beyond times of pathogen exposure?  

PubMed

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

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

2014-03-01

83

Exploratory study on a statistical method to analyse time resolved data obtained during nanomaterial exposure measurements  

NASA Astrophysics Data System (ADS)

Most of the measurement strategies that are suggested at the international level to assess workplace exposure to nanomaterials rely on devices measuring, in real time, airborne particles concentrations (according different metrics). Since none of the instruments to measure aerosols can distinguish a particle of interest to the background aerosol, the statistical analysis of time resolved data requires special attention. So far, very few approaches have been used for statistical analysis in the literature. This ranges from simple qualitative analysis of graphs to the implementation of more complex statistical models. To date, there is still no consensus on a particular approach and the current period is always looking for an appropriate and robust method. In this context, this exploratory study investigates a statistical method to analyse time resolved data based on a Bayesian probabilistic approach. To investigate and illustrate the use of the this statistical method, particle number concentration data from a workplace study that investigated the potential for exposure via inhalation from cleanout operations by sandpapering of a reactor producing nanocomposite thin films have been used. In this workplace study, the background issue has been addressed through the near-field and far-field approaches and several size integrated and time resolved devices have been used. The analysis of the results presented here focuses only on data obtained with two handheld condensation particle counters. While one was measuring at the source of the released particles, the other one was measuring in parallel far-field. The Bayesian probabilistic approach allows a probabilistic modelling of data series, and the observed task is modelled in the form of probability distributions. The probability distributions issuing from time resolved data obtained at the source can be compared with the probability distributions issuing from the time resolved data obtained far-field, leading in a quantitative estimation of the airborne particles released at the source when the task is performed. Beyond obtained results, this exploratory study indicates that the analysis of the results requires specific experience in statistics.

Clerc, F.; Njiki-Menga, G.-H.; Witschger, O.

2013-04-01

84

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...

85

Critical time delay of the pineal melatonin rhythm in humans due to weak electromagnetic exposure.  

PubMed

Electromagnetic fields (EMFs) can increase free radicals, activate the stress response and alter enzyme reactions. Intracellular signalling is mediated by free radicals and enzyme kinetics is affected by radical pair recombination rates. The magnetic field component of an external EMF can delay the "recombination rate" of free radical pairs. Magnetic fields thus increase radical life-times in biological systems. Although measured in nanoseconds, this extra time increases the potential to do more damage. Melatonin regulates the body's sleep-wake cycle or circadian rhythm. The World Health Organization (WHO) has confirmed that prolonged alterations in sleep patterns suppress the body's ability to make melatonin. Considerable cancer rates have been attributed to the reduction of melatonin production as a result of jet lag and night shift work. In this study, changes in circadian rhythm and melatonin concentration are observed due to the external perturbation of chemical reaction rates. We further analyze the pineal melatonin rhythm and investigate the critical time delay or maturation time of radical pair recombination rates, exploring the impact of the mRNA degradation rate on the critical time delay. The results show that significant melatonin interruption and changes to the circadian rhythm occur due to the perturbation of chemical reaction rates, as also reported in previous studies. The results also show the influence of the mRNA degradation rate on the circadian rhythm's critical time delay or maturation time. The results support the hypothesis that exposure to weak EMFs via melatonin disruption can adversely affect human health. PMID:24772943

Halgamuge, Malka N

2013-08-01

86

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

PubMed

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

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

2011-10-01

87

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

SciTech Connect

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.

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

88

The interactive effects of chytrid fungus, pesticides, and exposure timing on gray treefrog (Hyla versicolor) larvae.  

PubMed

Aquatic organisms are often exposed to a wide variety of perturbations in nature, including pathogens and chemical contaminants. Despite the co-occurrence of these 2 stressors, few studies have examined the effects of chemical contaminants on host-pathogen dynamics. The authors tested the individual and combined effects on gray treefrog (Hyla versicolor) tadpoles of 2 commonly used pesticides (Roundup® and Sevin®) and the pathogenic fungus Batrachochytrium dendrobatidis (Bd). A fully factorial design was used, and tadpoles were exposed to Bd, Roundup, or Sevin alone, or a combination of Bd and either pesticide at 3 points during larval development (early, mid, late). It was predicted that pesticides would mediate the effect of Bd on tadpoles and reduce the likelihood of negative consequences of infection and that timing of exposure would influence these effects. Tadpoles exposed to Bd at the mid point experienced higher survival through metamorphosis than those exposed to Bd at the early or late points, while tadpoles exposed to Sevin at the early point experienced reduced survival compared with those exposed to Roundup or no-pesticide control at the same exposure point. Roundup ameliorated the effects of Bd on survival compared with tadpoles exposed to Bd alone, while there was no interactive effect of Sevin on survival. In addition, Sevin reduced mass of new metamorphs compared with Roundup and reduced snout-vent length compared with all other treatments. The present study supports the hypothesis that pesticides can mitigate the effects of Bd on amphibian hosts and that such effects may depend on the timing of exposure. PMID:24259231

Hanlon, Shane M; Parris, Matthew J

2014-01-01

89

Time Averaged Transmitter Power and Exposure to Electromagnetic Fields from Mobile Phone Base Stations  

PubMed Central

Models for exposure assessment of high frequency electromagnetic fields from mobile phone base stations need the technical data of the base stations as input. One of these parameters, the Equivalent Radiated Power (ERP), is a time-varying quantity, depending on communication traffic. In order to determine temporal averages of the exposure, corresponding averages of the ERP have to be available. These can be determined as duty factors, the ratios of the time-averaged power to the maximum output power according to the transmitter setting. We determine duty factors for UMTS from the data of 37 base stations in the Swisscom network. The UMTS base stations sample contains sites from different regions of Switzerland and also different site types (rural/suburban/urban/hotspot). Averaged over all regions and site types, a UMTS duty factor F ? 0.32 ± 0.08 for the 24 h-average is obtained, i.e., the average output power corresponds to about a third of the maximum power. We also give duty factors for GSM based on simple approximations and a lower limit for LTE estimated from the base load on the signalling channels. PMID:25105551

Burgi, Alfred; Scanferla, Damiano; Lehmann, Hugo

2014-01-01

90

Time averaged transmitter power and exposure to electromagnetic fields from mobile phone base stations.  

PubMed

Models for exposure assessment of high frequency electromagnetic fields from mobile phone base stations need the technical data of the base stations as input. One of these parameters, the Equivalent Radiated Power (ERP), is a time-varying quantity, depending on communication traffic. In order to determine temporal averages of the exposure, corresponding averages of the ERP have to be available. These can be determined as duty factors, the ratios of the time-averaged power to the maximum output power according to the transmitter setting. We determine duty factors for UMTS from the data of 37 base stations in the Swisscom network. The UMTS base stations sample contains sites from different regions of Switzerland and also different site types (rural/suburban/urban/hotspot). Averaged over all regions and site types, a UMTS duty factor for the 24 h-average is obtained, i.e., the average output power corresponds to about a third of the maximum power. We also give duty factors for GSM based on simple approximations and a lower limit for LTE estimated from the base load on the signalling channels. PMID:25105551

Bürgi, Alfred; Scanferla, Damiano; Lehmann, Hugo

2014-08-01

91

Time to pregnancy and exposure to pesticides in Danish farmers. ASCLEPIOS Study Group  

PubMed Central

OBJECTIVE: Circumstantial evidence suggests that organic farmers may have higher sperm count than other men, but comprehensive epidemiological studies of male fecundity among farmers have never been carried out. A substantial increase of sperm count is expected to translate into a shorter time to pregnancy--the number of menstrual cycles or months it takes a couple to get pregnant from discontinuation of birth control. Toxicological effects on spermatogenesis in humans and animals have been described after exposure to several pesticides. The aim of this study was to examine time to pregnancy among farmers who used pesticides (traditional farmers) and farmers who did not (organic farmers). METHODS: A total of 904 (84%) men, selected from the Danish Ministry of Agriculture lists of traditional and organic farmers, participated in telephone interviews. Information was collected on time to pregnancy for the youngest child, exposure to pesticides, and potential confounders. RESULTS: With the discrete analogue of the Cox regression model (including potential confounders: male and female smoking, female age, parity, and contraceptive method), the fecundability ratio between traditional farmers who used pesticides and organic farmers was 1.03 (95% confidence interval (95% CI) 0.75 to 1.40). In the group of farmers who sprayed with pesticides, none of the characteristics related to the use of pesticides could account for the variation in time to pregnancy. CONCLUSIONS: No overall effect of pesticides on male fecundability was found in this retrospective study among Danish farmers. Also, we found no evidence of higher male fecundability in organic farmers.   PMID:9624283

Larsen, S. B.; Joffe, M.; Bonde, J. P.

1998-01-01

92

Time-dependent inhibition of Na + \\/K + ATPase induced by single and simultaneous exposure to lead and cadmium  

Microsoft Academic Search

Time-dependent interactions of Na+\\/K+-ATPase, isolated from rat brain synaptic plasma membranes (SPMs), with Cd2+ and Pb2+ ions in a single exposure and in a mixture were investigated in vitro. The interference of the enzyme with these metal ions\\u000a was studied as a function of different protein concentrations and exposure time. The aim of the work was to investigate the\\u000a possibility

V. Vasi?; D. Kojic; K. Krinulovic; M. ?olovi?; A. Vujacic; D. Stojic

2007-01-01

93

Changes in soft tissue concentrations of plutonium and americium with time after human occupational exposure  

SciTech Connect

Concentrations of {sup 239+240}Pu and {sup 241}Am in human soft tissues (testes, thyroid gland, kidneys, spleen, heart, skeletal muscle, brain, and pancreas) were compared to those in the livers of the same subject. The subjects were volunteer donors with occupational exposures to plutonium and americium autopsied as part of the United States Transuranium and Uranium Registries program. The temporal distributions of tissue-to-liver ratios were compared to liver uptake fractions assumed on the basis of current models to estimate the initial uptake fractions for each tissue studied. Regressions of the ratios were used to compare tissue retention half-times of those of the liver. Effective half-times for plutonium and americium in the tissues studied were similiar to those for the liver with three exceptions: (1) the clearance half-time for plutonium in kidneys is shorter that that of liver; (2) the retention half-time for plutonium is testes is longer that that of liver; and (3) the retention half-time for americium in skeletal muscle was longer than in the liver. Next to liver, the greatest initial uptake of systemic actinides was in skeletal muscle and the greatest initial concentrations were in the spleen. The uptake fraction of plutonium in the testes proposed by the ICRP was verified. 20 refs., 2 figs., 5 tabs.

Filipy, R.E.; Kathren, R.L. [Washington State Univ., Richland, VA (United States)

1996-02-01

94

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

NASA Astrophysics Data System (ADS)

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.

Mizunami, Toru; Fujiyoshi, Tsubasa

2014-08-01

95

Color Stability of Enamel following Different Acid Etching and Color Exposure Times  

PubMed Central

Background and aims. The aim of this study was to evaluate the effect of different etching times on enamel color stability after immediate versus delayed exposure to colored artificial saliva (CAS). Materials and methods. Human first premolars were divided into five groups of twenty. A colorimeter was used according to the CIE system on the mid-buccal and mid-lingual surfaces to evaluate initial tooth color. Samples in group A remained unetched. In groups B to E, buccal and lingual surfaces were initially etched with phosphoric acid for 15 and 60 seconds, respectively. Then, the samples in groups A and C were immersed in colored artificial saliva (cola+saliva). In group B, the teeth were immersed in simple artificial saliva (AS). Samples in groups D and E were immersed in AS for 24 and 72 hours, respectively before being immersed in colored AS. The teeth were immersed for one month in each solution before color measurement. During the test period, the teeth were retrieved from the staining solution and stored in AS for five minutes. This was repeated 60 times. Color changes of buccal and lingual surfaces were calculated. Kruskal-Wallis and Wilcoxon tests were used for statistical analysis (? ?0.05). Results. There were no significant differences between the groups in term of ?E of buccal (P = 0.148) and lingual surfaces (P = 0.73). Conclusion. Extended time of etching did not result in significant enamel color change. Immediate and delayed exposure of etched enamel to staining solutions did not result in clinically detectable tooth color changes. PMID:25093048

Jahanbin, Arezoo; Basafa, Mohammad; Moazzami, Mostafa; Basafa, Behnoush; Eslami, Neda

2014-01-01

96

In-situ hydrogen in metal determination using a minimum neutron source strength and exposure time.  

PubMed

Water is frequently present in the environment and is a source of hydrogen that can interact with many materials. Because of its small atomic size, a hydrogen atom can easily diffuse into a host metal, and though the metal may appear unchanged for a time, the metal will eventually abruptly lose its strength and ductility. Thus, measuring the hydrogen content in metals is important in many fields, such as in the nuclear industry, in automotive and aircraft fabrication, and particularly, in offshore oil and gas fields. It has been demonstrated that the use of nuclear methods to measure the hydrogen content in metals can achieve sensitivity levels on the order of parts per million. However, the use of nuclear methods in the field has not been conducted for two reasons. The first reason is due to exposure limitations. The second reason is due to the hi-tech instruments required for better accuracy. In this work, a new method using a low-strength portable neutron source is explored in conjunction with detectors based on plastic nuclear detection films. The following are the in-situ requirements: simplicity in setup, high reliability, minimal exposure dose, and acceptable accuracy at an acceptable cost. A computer model of the experimental setup is used to reproduce the results of a proof-of-concept experiment and to predict the sensitivity levels under optimised experimental conditions. PMID:23708832

Hatem, M; Agamy, S; Khalil, M Y

2013-08-01

97

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...

98

Human short-term exposure to electromagnetic fields emitted by mobile phones decreases computer-assisted visual reaction time.  

PubMed

The worldwide dramatic increase in mobile phone use has generated great concerns about the detrimental effects of microwave radiations emitted by these communication devices. Reaction time plays a critical role in performing tasks necessary to avoid hazards. As far as we know, this study is the first survey that reports decreased reaction time after exposure to electromagnetic fields generated by a high specific absorption rate mobile phone. It is also the first study in which previous history of mobile phone use is taken into account. The aim of this study was to assess both the acute and chronic effects of electromagnetic fields emitted by mobile phones on reaction time in university students. Visual reaction time (VRT) of young university students was recorded with a simple blind computer-assisted-VRT test, before and after a 10 min real/sham exposure to electromagnetic fields of mobile phones. Participants were 160 right-handed university students aged 18-31. To assess the effect of chronic exposures, the reaction time in sham-exposed phases were compared among low level, moderate and frequent users of mobile phones. The mean ± SD reaction time after real exposure and sham exposure were 286.78 ± 31.35 ms and 295.86 ± 32.17 ms (P < 0.001), respectively. The age of students did not significantly alter the reaction time either in talk or in standby mode. The reaction time either in talk or in standby mode was shorter in male students. The students' VRT was significantly affected by exposure to electromagnetic fields emitted by a mobile phone. It can be concluded that these exposures cause decreased reaction time, which may lead to a better response to different hazards. In this light, this phenomenon might decrease the chances of human errors and fatal accidents. PMID:22426673

Mortazavi, S M J; Rouintan, M S; Taeb, S; Dehghan, N; Ghaffarpanah, A A; Sadeghi, Z; Ghafouri, F

2012-06-01

99

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

PubMed

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

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

100

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

101

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

PubMed

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

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

2014-06-01

102

Influence of temperature and storage time after light exposure on the quinine monohydrochloride chemical actinometric system  

Microsoft Academic Search

The ICH guideline on photostability has proposed quinine monohydrochloride chemical actinometric system as a standard method for measuring light exposure during photostability testing. A change in the absorption at 400 nm of quinine monohydrochloride after light exposure corresponds to a defined dose of light. The present work investigated the effect of temperature, light exposure level and the dark reactions following

Karin L Christensen; Janne Ø Christensen; Sven Frokjaer; Peter Langballe; Lars L Hansen

2000-01-01

103

Exposures to Synthetic Estrogens at Different Times During the Life, and Their Effect on Breast Cancer Risk  

PubMed Central

Women are using estrogens for many purposes, such as to prevent pregnancy or miscarriage, or to treat menopausal symptoms. Estrogens also have been used to treat breast cancer which seems puzzling, since there is convincing evidence to support a link between high lifetime estrogen exposure and increased breast cancer risk. In this review, we discuss the findings that maternal exposure to the synthetic estrogen diethylstilbestrol during pregnancy increases breast cancer risk in both exposed mothers and their daughters. In addition, we review data regarding the use of estrogens in oral contraceptives and as postmenopausal hormone therapy and discuss the opposing effects on breast cancer risk based upon timing of exposure. We place particular emphasis on studies investigating how maternal estrogenic exposures during pregnancy increase breast cancer risk among daughters. New data suggest that these exposures induce epigenetic modifications in the mammary gland and germ cells, thereby causing an inheritable increase in breast cancer risk for multiple generations. PMID:23392570

de Assis, Sonia; Warri, Anni

2013-01-01

104

Gene expression pattern in swine neutrophils after lipopolysaccharide exposure: a time course comparison  

PubMed Central

Background Experimental exposure of swine neutrophils to bacterial lipopolysaccharide (LPS) represents a model to study the innate immune response during bacterial infection. Neutrophils can effectively limit the infection by secreting lipid mediators, antimicrobial molecules and a combination of reactive oxygen species (ROS) without new synthesis of proteins. However, it is known that neutrophils can modify the gene expression after LPS exposure. We performed microarray gene expression analysis in order to elucidate the less known transcriptional response of neutrophils during infection. Methods Blood samples were collected from four healthy Iberian pigs and neutrophils were isolated and incubated during 6, 9 and 18 hrs in presence or absence of lipopolysaccharide (LPS) from Salmonella enterica serovar Typhimurium. RNA was isolated and hybridized to Affymetrix Porcine GeneChip®. Microarray data were normalized using Robust Microarray Analysis (RMA) and then, differential expression was obtained by an analysis of variance (ANOVA). Results ANOVA data analysis showed that the number of differentially expressed genes (DEG) after LPS treatment vary with time. The highest transcriptional response occurred at 9 hr post LPS stimulation with 1494 DEG whereas at 6 and 18 hr showed 125 and 108 DEG, respectively. Three different gene expression tendencies were observed: genes in cluster 1 showed a tendency toward up-regulation; cluster 2 genes showing a tendency for down-regulation at 9 hr; and cluster 3 genes were up-regulated at 9 hr post LPS stimulation. Ingenuity Pathway Analysis revealed a delay of neutrophil apoptosis at 9 hr. Many genes controlling biological functions were altered with time including those controlling metabolism and cell organization, ubiquitination, adhesion, movement or inflammatory response. Conclusions LPS stimulation alters the transcriptional pattern in neutrophils and the present results show that the robust transcriptional potential of neutrophils under infection conditions, indicating that active regulation of gene expression plays a major role in the neutrophil-mediated- innate immune response. PMID:21645290

2011-01-01

105

Time-dependent Changes of Cadmium and Metallothionein after Short-term Exposure to Cadmium in Rats  

PubMed Central

The time-dependent changes in cadmium (Cd) concentration were studied in Female Sprague-Dawley (SD) rats during and after Cd exposure via drinking water (10 and 50 ppm) for 30 days. The cadmium concentration in muscle, liver, kidney, blood plasma, and urine, and the metallothionein concentration in blood plasma were determined every 10 days during exposure and every 7 days after exposure for 3 weeks. The muscle Cd concentration did not change during, and neither after, exposure. The liver Cd concentration increased from 1.4 to 3.3 (at 10 ppm) and from 6.1 to 10.1 folds (at 50 ppm) during exposure and remained higher than those of controls in both groups even during post-exposure period. The kidney Cd concentrations were 2.3 to 5.1 (at 10 ppm) and 4.9-14.0 folds (at 50 ppm) higher than those of controls during exposure and also remained elevated during the post-exposure period. Plasma Cd concentrations were not significantly different from those of controls in both groups. Urine Cd concentrations were more than 2 folds (at 10 ppm) and 6.5 to 12.6 folds (at 50 ppm) higher than those of controls but rapidly decreased over the 7 days of withdrawal. Blood plasma metallothionein concentrations were more than 2.4 folds (at 10 ppm) and 3.1 to 7.4 folds (at 50 ppm) , and they remained elevated till 7 days (10 ppm) and 14 days (at 50 ppm) after exposure. Our data support that Cd in urine could be a useful biomarker during Cd exposure period and metallothionein in blood plasma could be as a supportive biological marker for during and post Cd exposure. PMID:24278516

Cho, Mi Ran; Jeong, Sang-Hee; Cho, Myung Haing

2010-01-01

106

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

PubMed Central

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

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

107

Near Real-Time Earthquake Exposure and Damage Assessment: An Example from Turkey  

NASA Astrophysics Data System (ADS)

Confined by infamous strike-slip North Anatolian Fault from the north and by the Hellenic subduction trench from the south Turkey is one of the most seismically active countries in Europe. Due this increased exposure and the fragility of the building stock Turkey is among the top countries exposed to earthquake hazard in terms of mortality and economic losses. In this study we focus recent and ongoing efforts to mitigate the earthquake risk in near real-time. We present actual results of recent earthquakes, such as the M6 event off-shore Antalya which occurred on 28 December 2013. Starting at the moment of detection, we obtain a preliminary ground motion intensity distribution based on epicenter and magnitude. Our real-time application is further enhanced by the integration of the SeisComp3 ground motion parameter estimation tool with the Earthquake Loss Estimation Routine (ELER). SeisComp3 provides the online station parameters which are then automatically incorporated into the ShakeMaps produced by ELER. The resulting ground motion distributions are used together with the building inventory to calculate expected number of buildings in various damage states. All these analysis are conducted in an automated fashion and are communicated within a few minutes of a triggering event. In our efforts to disseminate earthquake information to the general public we make extensive use of social networks such as Tweeter and collaborate with mobile phone operators.

Kamer, Yavor; Çomo?lu, Mustafa; Erdik, Mustafa

2014-05-01

108

Does oxygen exposure time control the extent of organic matter decomposition in peatlands?  

NASA Astrophysics Data System (ADS)

extent of peat decomposition was investigated in four cores collected along a latitudinal gradient from 56°N to 66°N in the West Siberian Lowland. The acid:aldehyde ratios of lignin phenols were significantly higher in the two northern cores compared with the two southern cores, indicating peats at the northern sites were more highly decomposed. Yields of hydroxyproline, an amino acid found in plant structural glycoproteins, were also significantly higher in northern cores compared with southern cores. Hydroxyproline-rich glycoproteins are not synthesized by microbes and are generally less reactive than bulk plant carbon, so elevated yields indicated that northern cores were more extensively decomposed than the southern cores. The southern cores experienced warmer temperatures, but were less decomposed, indicating that temperature was not the primary control of peat decomposition. The plant community oscillated between Sphagnum and vascular plant dominance in the southern cores, but vegetation type did not appear to affect the extent of decomposition. Oxygen exposure time appeared to be the strongest control of the extent of peat decomposition. The northern cores had lower accumulation rates and drier conditions, so these peats were exposed to oxic conditions for a longer time before burial in the catotelm, where anoxic conditions prevail and rates of decomposition are generally lower by an order of magnitude.

Philben, Michael; Kaiser, Karl; Benner, Ronald

2014-05-01

109

Time dependent wettability of graphite upon ambient exposure: The role of water adsorption  

NASA Astrophysics Data System (ADS)

We report the temporal evolution of the wettability of highly ordered pyrolytic graphite (HOPG) exposed to environmental conditions. Macroscopic wettability is investigated by static and dynamic contact angles (SCA and DCA) obtaining values comparable to the ones presented in the literature. SCA increases from ˜68° to ˜90° during the first hour of exposure after cleaving, whereas DCA is characterized by longer-scale (24 h) time evolution. We interpret these results in light of Fourier transform infrared spectroscopy, which indicates that the evolution of the HOPG wettability is due to adsorption of molecules from the surrounding atmosphere. This hypothesis is further confirmed by nanoscopic observations obtained by atomic force microscope (AFM)-based force spectroscopy, which monitor the evolution of surface properties with a spatial resolution superior to macroscopic experiments. Moreover, we observe that the results of macro- and nanoscale measurements evolve in similar fashion with time and we propose a quantitative correlation between SCA and AFM measurements. Our results suggest that the cause of the transition in the wettability of HOPG is due to the adsorption of hydrocarbon contaminations and water molecules from the environment. This is corroborated by annealing the HOPG is vacuum conditions at 150°, allowing the desorption of molecules on the surface, and thus re-establishing the initial macro and nano surface properties. Our findings can be used in the interpretation of the wettability of more complicated systems derived from HOPG (i.e., graphene).

Amadei, Carlo A.; Lai, Chia-Yun; Heskes, Daan; Chiesa, Matteo

2014-08-01

110

Survival rate of frozen-thawed bovine IVF embryos in relation to exposure time using various cryoprotectants.  

PubMed

The relationship between cryoprotectant and exposure time on the development of IVF-derived embryos in culture after freezing and thawing was examined. Good to excellent quality Day 7 to 8 blastocysts and expanded blastocysts were suspended in 1.6 M propylene glycol (PG), 1.8 M ethylene glycol (EG), 1.1 M diethylene glycol, and 1.3 M ethylene glycol monomethyl ether (EME). In Experiment I, after 30 and 120 min of exposure, embryos were placed directly into culture medium and washed three times. Embryos were cocultured with cumulus cells in culture medium. After a 48-h culture, there were no significant differences in fully expanded, hatching, and hatched rates between the 30- and 120-min exposure to all four cryoprotectants except for the fully expanded rate with PG (55 vs 83%). In Experiment II, to compare the cryoprotective effects of the four cryoprotectants, embryos were exposed to each cryoprotectant for variable times from 10 to 120 min, seeded, and cooled to -30 degrees C at 0.3 degree C/min, plunged into liquid nitrogen for storage, and then thawed. Survival was measured by coculturing the embryos with cumulus cells in culture medium. There were no significant differences in development to hatched blastocysts of embryos exposed to either PG (27-42%) or EG (37-56%). The number of embryos developing after exposure to EME was similar to that in PG or EG when exposure time did not exceed 40 min (43-49%). Our findings suggest that the toxicity of different cryoprotectants is related to the exposure time and that PG and EG were relatively nontoxic as is exposure to EME for short periods. PMID:8370317

Takagi, M; Boediono, A; Saha, S; Suzuki, T

1993-06-01

111

Radiation Exposure Time during MBSS: Influence of Swallowing Impairment Severity, Medical Diagnosis, Clinician Experience, and Standardized Protocol Use  

PubMed Central

Purpose Guidelines and preventive measures have been established to limit radiation exposure time during modified barium swallow studies (MBSS) but multiple variables may influence exam duration. This study examines the influence of clinician experience, medical diagnosis category, swallowing impairment severity and use of a standardized protocol on fluoroscopy time. Methods A retrospective review was completed on 739 MBSSs performed on 612 patients (342 males/270 females; age range = 18 to 96 years) completed in one year at the Medical University of South Carolina with IRB approval. All studies were completed by speech-language pathologists trained in the data collection protocol, interpretation, and scoring of the MBSImP™©. Medical diagnosis category, swallowing impairment severity (MBSImP™© score), clinician experience, and fluoroscopy time were the variables recorded for analysis. Results Fluoroscopy time was not significantly associated with medical diagnosis category (p=0.10). The severity of the MBSImP©™ Oral Total and Pharyngeal Total resulted in statistically significant increases in fluoroscopy time (p<0.05). Studies by novice clinicians had longer exposure times when compared to experienced clinicians (p=0.037). Average radiation exposure time using the MBSImP©™ approach was 2.9 minutes, with a 95% confidence interval of 2.8 minutes to 3.0 minutes, which was well within the range of exposure times reported in the literature. Conclusions This study provides preliminary information regarding the impact of medical diagnosis category, swallowing impairment severity and clinician experience on fluoroscopy time. These findings also suggest that a thorough, standardized protocol for MBSSs did not cause unnecessary radiation exposure time during the MBSS. PMID:22692431

Bonilha, Heather Shaw; Humphries, Kate; Blair, Julie; Hill, Elizabeth G; McGrattan, Katlyn; Carnes, Brittni; Huda, Walter; Martin-Harris, Bonnie

2012-01-01

112

Time-patterns of antibiotic exposure in poultry production--a Markov chains exploratory study of nature and consequences.  

PubMed

This article describes the use of Markov chains to explore the time-patterns of antimicrobial exposure in broiler poultry. The transition in antimicrobial exposure status (exposed/not exposed to an antimicrobial, with a distinction between exposures to the different antimicrobial classes) in extensive data collected in broiler chicken flocks from November 2003 onwards, was investigated. All Markov chains were first-order chains. Mortality rate, geographical location and slaughter semester were sources of heterogeneity between transition matrices. Transitions towards a 'no antimicrobial' exposure state were highly predominant, whatever the initial state. From a 'no antimicrobial' exposure state, the transition to beta-lactams was predominant among transitions to an antimicrobial exposure state. Transitions between antimicrobial classes were rare and variable. Switches between antimicrobial classes and repeats of a particular class were both observed. Application of Markov chains analysis to the database of the nation-wide antimicrobial resistance monitoring programme pointed out that transition probabilities between antimicrobial exposure states increased with the number of resistances in Escherichia coli strains. PMID:17386950

Chauvin, C; Clement, C; Bruneau, M; Pommeret, D

2007-07-16

113

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

PubMed

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

Huang, Kuo-Chen; Yeh, Po-Chan

2007-04-01

114

Bayesian algorithm implementation in a real time exposure assessment model on benzene with calculation of associated cancer risks.  

PubMed

The objective of the current study was the development of a reliable modeling platform to calculate in real time the personal exposure and the associated health risk for filling station employees evaluating current environmental parameters (traffic, meteorological and amount of fuel traded) determined by the appropriate sensor network. A set of Artificial Neural Networks (ANNs) was developed to predict benzene exposure pattern for the filling station employees. Furthermore, a Physiology Based Pharmaco-Kinetic (PBPK) risk assessment model was developed in order to calculate the lifetime probability distribution of leukemia to the employees, fed by data obtained by the ANN model. Bayesian algorithm was involved in crucial points of both model sub compartments. The application was evaluated in two filling stations (one urban and one rural). Among several algorithms available for the development of the ANN exposure model, Bayesian regularization provided the best results and seemed to be a promising technique for prediction of the exposure pattern of that occupational population group. On assessing the estimated leukemia risk under the scope of providing a distribution curve based on the exposure levels and the different susceptibility of the population, the Bayesian algorithm was a prerequisite of the Monte Carlo approach, which is integrated in the PBPK-based risk model. In conclusion, the modeling system described herein is capable of exploiting the information collected by the environmental sensors in order to estimate in real time the personal exposure and the resulting health risk for employees of gasoline filling stations. PMID:22399936

Sarigiannis, Dimosthenis A; Karakitsios, Spyros P; Gotti, Alberto; Papaloukas, Costas L; Kassomenos, Pavlos A; Pilidis, Georgios A

2009-01-01

115

The Role of Gis: Coping With Space (And Time) in Air Pollution Exposure Assessment  

Microsoft Academic Search

Geographical information systems (GIS) offer potentially powerful tools for exposure assessment in support of both air pollution epidemiology and air quality policy. To date, however, most epidemiological applications have relied on relatively simple techniques, such as buffering and distance functions. In part, this reflects the often limited understanding of the underlying exposure pathways or etiology and the nonspecific nature of

David Briggs

2005-01-01

116

A Cohort study evaluation of maternal PCB exposure related to time to pregnancy in daughters  

PubMed Central

Background Polychlorinated biphenyls (PCBs) remain ubiquitous environmental contaminants. Developmental exposures are suspected to impact reproduction. Analysis of mixtures of PCBs may be problematic as components have a complex correlation structure, and along with limited sample sizes, standard regression strategies are problematic. We compared the results of a novel, empirical method to those based on categorization of PCB compounds by (1) hypothesized biological activity previously proposed and widely applied, and (2) degree of ortho- substitution (mono, di, tri), in a study of the relation of maternal serum PCBs and daughter’s time to pregnancy. Methods We measured PCBs in maternal serum samples collected in the early postpartum in 289 daughters in the Child Health and Development Studies birth cohort. We queried time to pregnancy in these daughters 28–31 years later. We applied a novel weighted quantile sum approach to find the bad-actor compounds in the PCB mixture found in maternal serum. The approach includes empirical estimation of the weights through a bootstrap step which accounts for the variation in the estimated weights. Results Bootstrap analyses indicated the dominant functionality groups associated with longer TTP were the dioxin-like, anti-estrogenic group (average weight, 22%) and PCBs not previously classified by biological activity (54%). In contrast, the unclassified PCBs were not important in the association with shorter TTP, where the anti-estrogenic groups and the PB-inducers group played a more important role (60% and 23%, respectively). The highly chlorinated PCBs (average weight, 89%) were mostly associated with longer TTP; in contrast, the degree of chlorination was less discriminating for shorter TTP. Finally, PCB 56 was associated with the strongest relationship with TTP with a weight of 47%. Conclusions Our empirical approach found some associations previously identified by two classification schemes, but also identified other bad actors. This empirical method can generate hypotheses about mixture effects and mechanisms and overcomes some of the limitations of standard regression techniques. PMID:23962309

2013-01-01

117

The efficacy of protoporphyrin as a predictive biomarker for lead exposure in canvasback ducks: Effect of sample storage time.  

PubMed

We used 363 blood samples collected from wild canvasback dueks (Aythya valisineria) at Catahoula Lake, Louisiana, U.S.A. to evaluate the effect of sample storage time on the efficacy of erythrocytic protoporphyrin as an indicator of lead exposure. The protoporphyrin concentration of each sample was determined by hematofluorometry within 5 min of blood collection and after refrigeration at 4 °C for 24 and 48 h. All samples were analyzed for lead by atomic absorption spectrophotometry. Based on a blood lead concentration of ?0.2 ppm wet weight as positive evidence for lead exposure, the protoporphyrin technique resulted in overall error rates of 29%, 20%, and 19% and false negative error rates of 47%, 29% and 25% when hematofluorometric determinations were made on blood at 5 min, 24 h, and 48 h, respectively. False positive error rates were less than 10% for all three measurement times. The accuracy of the 24-h erythrocytic protoporphyrin classification of blood samples as positive or negative for lead exposure was significantly greater than the 5-min classification, but no improvement in accuracy was gained when samples were tested at 48 h. The false negative errors were probably due, at least in part, to the lag time between lead exposure and the increase of blood protoporphyrin concentrations. False negatives resulted in an underestimation of the true number of canvasbacks exposed to lead, indicating that hematofluorometry provides a conservative estimate of lead exposure. PMID:24193824

Christian Franson, J; Hohman, W L; Moore, J L; Smith, M R

1996-11-01

118

Specific time of exposure during tadpole development influences biological effects of the insecticide carbaryl in green frogs (Lithobates clamitans).  

PubMed

The orchestration of anuran metamorphosis is initiated and integrated by thyroid hormones, which change dynamically during larval development and which may represent a target of disruption by environmental contaminants. Studies have found that some anurans experience increased rates of development when exposed to the insecticide carbaryl later in larval development, suggesting that this insecticide could affect thyroid hormone-associated biological pathways. However, the time in development when tadpoles are sensitive to insecticide exposure has not been clearly defined nor has the mechanism been tested. In two separate studies, we exposed recently hatched green frog (Lithobates clamitans) tadpoles to a single, three day carbaryl exposure in the laboratory at either 2, 4, 8, or 16 weeks post-hatching. We examined the impact of carbaryl exposure on mRNA abundance patterns in the brains of frogs following metamorphosis months after a single three day exposure (experiment 1) and in tadpole tails three days after exposure (experiment 2) using cDNA microarrays and quantitative real time polymerase chain reaction (QPCR) analyses. For tadpoles reared through metamorphosis, we measured tadpole growth and development, as well as time to, mass at, and survival to metamorphosis. Although carbaryl did not significantly impact tadpole development, metamorphosis, or survival, clear exposure-related alterations in both tail and brain transcript levels were evident when tadpoles were exposed to carbaryl, particularly in tadpoles exposed at weeks 8 and 16 post-hatching, indicating both short-term and long-term alterations in mRNA expression. These results indicate that carbaryl can have long-lasting effects on brain development when exposure occurs at sensitive developmental stages, which may have implications for animal fitness and function later in the life cycle. PMID:23399446

Boone, Michelle D; Hammond, S Austin; Veldhoen, Nik; Youngquist, Melissa; Helbing, Caren C

2013-04-15

119

Assessment of time to pregnancy and spontaneous abortion status following occupational exposure to organic solvents mixture  

Microsoft Academic Search

Purpose  Due to increasing usage of chemicals in various industries, occupational exposure of women with these materials is unavoidable.\\u000a Nowadays, some studies indicate adverse effects of exposure to these chemicals, especially organic solvents on the reproductive\\u000a system of females. This study aimed to assess the relationship between spontaneous abortion and occupational exposure to organic\\u000a solvents mixture in pharmaceutical industry.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  This study

Mir Saeed Attarchi; Monir Ashouri; Yasser Labbafinejad; Saber Mohammadi

120

PROSTATE CANCER: IS IT TIME TO EXPAND THE RESEARCH FOCUS TO EARLY-LIFE EXPOSURES?  

PubMed Central

Preface Although the contribution of lifestyle and environment (non-genetic factors) to prostate carcinogenesis is indicated by international variation in prostate cancer occurrence and migration studies, no conclusive modifiable risk factors have been identified to date. One possible reason for this may be the dearth of epidemiological research on exposures experienced early-in-life when the immature prostate may be more susceptible to carcinogenic exposures. Herein, we motivate the study of early-life exposures, describe the small body of early-life research and its associated challenges, and point towards solutions for future research. PMID:23363989

Sutcliffe, Siobhan; Colditz, Graham A.

2013-01-01

121

Advancing Environmental Noise Pollution Analysis in Urban Areas by Considering the Variation of Population Exposure in Space and Time  

NASA Astrophysics Data System (ADS)

Ambient noise is a subtle form of pollution in large urban areas, degrading human health and well-being. In Europe, directives require that urban environmental noise be measured and mapped for the main periods of the daily cycle. Subsequent analyses of human exposure to noise in those periods is usually conducted using resident (i.e., nighttime) population from the census and assuming constant densities within the enumeration units. However, population distribution and densities vary considerably from night to day in metropolitan areas, and disregard for that process results in gross misestimation of exposure to ambient noise in the daytime period. This study considers the spatio-temporal variation of population distribution in assessing exposure to ambient noise in a major urban area, the city of Lisbon, Portugal. Detailed and compatible day- and nighttime population distribution maps were used, developed by means of "intelligent dasymetric mapping". After categorizing noise levels in existing maps in each period, classified according to current legislation, human exposure to ambient noise was assessed with temporally matching population surfaces. Population exposure to noise in 2000 and 2009 was compared and further analyzed in regards to main source of noise, i.e. road traffic vs. aircraft.. Results show that human exposure to noise shifts substantially in time and space, with a significant increase in exposed population from the nighttime to daytime period, especially in the higher noise levels. This is due to the combined effects of the daily variation of noise patterns and population distribution.

Freire, S.; Gomes, N.

2013-05-01

122

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

PubMed

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

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

123

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...

124

Double short-time exposure to pirarubicin produces higher cytotoxicity against T24 bladder cancer cells  

Microsoft Academic Search

This study was designed to determine the ideal manner (schedule and duration) of intravesical chemotherapy using pirarubicin\\u000a (THP). At first, T-24 cancer cells were treated with 50, 100, 150, and 200 ?g\\/ml THP for 10, 30 and 60 min. Following the\\u000a first exposure, at various intervals (3, 6, 12, and 24 h), a second exposure to THP was performed under the same condition

Takuo Maruyama; Yoshihide Higuchi; Toru Suzuki; Jun Qiu; Shingo Yamamoto; Hiroki Shima

2011-01-01

125

The efficacy of protoporphyrin as a predictive biomarker for lead exposure in canvasback ducks: Effect of sample storage time  

Microsoft Academic Search

We used 363 blood samples collected from wild canvasback dueks (Aythya valisineria) at Catahoula Lake, Louisiana, U.S.A. to evaluate the effect of sample storage time on the efficacy of erythrocytic protoporphyrin as an indicator of lead exposure. The protoporphyrin concentration of each sample was determined by hematofluorometry within 5 min of blood collection and after refrigeration at 4 °C for

J. Christian Franson; William L. Hohman; Joseph L. Moore; Milton R. Smith

1996-01-01

126

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

Microsoft Academic Search

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

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

127

Early Life Exposures and the Occurrence and Timing of Heart Disease Among the Older Adult Puerto Rican Population  

Microsoft Academic Search

Few studies have examined the effects of early life conditions on the timing of the onset of heart disease. We use the remarkable example of a representative sample of the population of older Puerto Ricans aged 60–74 who lived in the countryside during childhood (n = 1,438) to examine the effects of seasonal exposures to poor nutrition and infectious diseases

Mary McEniry; Alberto Palloni

2010-01-01

128

Early Life Exposures and the Occurrence and Timing of Heart Disease Among the Older Adult Puerto Rican Population  

Microsoft Academic Search

:Few studies have examined the effects of early life conditions on the timing of the onset of heart disease. We use the remarkable example of a representative sample of the population of older Puerto Ricans aged 60–74 who lived in the countryside during childhood (n = 1,438) to examine the effects of seasonal exposures to poor nutrition and infectious diseases

Mary McEniry; Alberto Palloni

2010-01-01

129

Bayesian Algorithm Implementation in a Real Time Exposure Assessment Model on Benzene with Calculation of Associated Cancer Risks  

Microsoft Academic Search

The objective of the current study was the development of a reliable modeling platform to calculate in real time the personal exposure and the associated health risk for filling station employees evaluating current environmental parameters (traffic, meteorological and amount of fuel traded) determined by the appropriate sensor network. A set of Artificial Neural Networks (ANNs) was developed to predict benzene

Dimosthenis A. Sarigiannis; Spyros P. Karakitsios; Alberto Gotti; Costas L. Papaloukas; Pavlos A. Kassomenos; Georgios A. Pilidis

2009-01-01

130

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

ERIC Educational Resources Information Center

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…

Davis, Elysia P.; Sandman, Curt A.

2010-01-01

131

Real-time monitoring of intracellular cAMP during acute ethanol exposure  

PubMed Central

Background In previous studies we have shown that ethanol enhances the activity of Gs-stimulated membrane-bound adenylyl cyclase (AC). The effect is AC isoform specific and the type 7 AC (AC7) is most responsive to ethanol. In this study, we employed a fluorescence resonance energy transfer (FRET) based cAMP sensor, Epac1-camps, to examine real-time temporal dynamics of ethanol effects on cAMP concentrations. To our knowledge, this is the first report on real-time detection of the ethanol effect on intracellular cAMP. Methods Hela cells were transfected with Epac1-camps, dopamine D1A receptor, and one isoform of AC (AC7 or AC3). Fluorescent images were captured using a specific filter set for cyan fluorescent protein (CFP), yellow fluorescent protein (YFP), and FRET, respectively and FRET intensity was calculated on a pixel-by-pixel basis to examine changes in cAMP. Results During 2-minute stimulation with dopamine (DA), the cytoplasmic cAMP level quickly increased, then decreased to a plateau, where the cAMP level was higher than the level prior to stimulation with DA. Ethanol concentration dependently increased cytoplasmic cAMP in cells transfected with AC7, while ethanol did not have effect on cells transfected with AC3. Similar trends were observed for cAMP at the plasma membrane and in the nucleus during 2-minute stimulation with DA. Unexpectedly, when cells expressing AC7 were stimulated with DA or other Gs protein-coupled receptor’s ligand plus ethanol for 5 seconds, ethanol reduced cAMP concentration. Conclusion These results suggest that ethanol has two opposing effects on the cAMP generating system in an AC isoform specific manner, the enhancing effect on AC activity and the short lived inhibitory effect. Thus, ethanol may have a different effect on cAMP depending on not only AC isoform but also the duration of exposure. PMID:23731206

Gupta, Ratna; Qualls-Creekmore, Emily; Yoshimura, Masami

2013-01-01

132

A Pilot Study Characterizing Real Time Exposures to Particulate Matter and Carbon Monoxide from Cookstove Related Woodsmoke in Rural Peru  

PubMed Central

Nearly half of the world’s population is exposed to household air pollution (HAP) due to long hours spent in close proximity to unvented cooking fires. We aimed to use PM2.5 and CO measurements to characterize exposure to cookstove generated woodsmoke in real time among control (n=10) and intervention (n=9) households in San Marcos, Cajamarca Region, Peru. Real time personal particulate matter with an aerodynamic diameter ?2.5 µm (PM2.5), and personal and kitchen carbon monoxide (CO) samples were taken. Control households used a number of stoves including open fire and chimney stoves while intervention households used study-promoted chimney stoves. Measurements were categorized into lunch (9am – 1pm) and dinner (3pm – 7pm) periods, where applicable, to adjust for a wide range of sampling periods (2.8– 13.1hrs). During the 4-h time periods, mean personal PM2.5 exposures were correlated with personal CO exposures during lunch (r=0.67 p=0.024 n=11) and dinner (r=0.72 p=0.0011 n=17) in all study households. Personal PM2.5 exposures and kitchen CO concentrations were also correlated during lunch (r=0.76 p=0.018 n=9) and dinner (r=0.60 p=0.018 n=15). CO may be a useful indicator of PM during 4-h time scales measured in real time, particularly during high woodsmoke exposures, particularly during residential biomass cooking. PMID:24288452

Commodore, Adwoa A.; Hartinger, Stella M.; Lanata, Claudio F.; Mausezahl, Daniel; Gil, Ana I.; Hall, Daniel B.; Aguilar-Villalobos, Manuel; Naeher, Luke P.

2013-01-01

133

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

PubMed

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

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

2008-08-01

134

Quantitatively assessing flow velocity by the slope of the inverse square of the contrast values versus camera exposure time.  

PubMed

The slope of the inverse square of the contrast values versus camera exposure time at multi-exposure speckle imaging (MESI) can be a new indicator of flow velocity. The slope is linear as the diffuse coefficient in Brownian motion diffusion model and the mean velocity in ballistic motion model. Combining diffuse speckle contrast analysis (DSCA) and MESI, we demonstrate theoretically and experimentally that the flow velocity can be obtained from this slope. The calculation results processes of the slop don't need tedious Newtonian iterative method and are computationally inexpensive. The new indicator can play an important role in quantitatively assessing tissue blood flow velocity. PMID:25321017

Liu, Jialin; Zhang, Hongchao; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu

2014-08-11

135

Community Violence Exposure and Adolescents' School Engagement and Academic Achievement Over Time  

PubMed Central

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

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

2013-01-01

136

One-time screening to define the problem: Legionella exposure in an electric power company  

SciTech Connect

An electric utility screened 1455 production employees for job exposure to Legionella pneumophila sources, illness history, and antibodies to L pneumophila serotypes I-IV. L pneumophila-associated illness outbreaks had occurred in a neighboring electric utility district; bacteria serocompatible with L pneumophila had been detected in all four plants participating in an environmental survey, and the company was concerned about the implications of these findings for their employees and the public living near power plants with large cooling towers. The survey revealed a prevalence of antibodies in employees consistent with general population surveys. Within the employee group, antibody titer was not associated with either reports of recent illness or work exposure to potential L pneumophila sources. Inability to detect a relationship between exposure to potential L pneumophila sources and specific antibody results was used to define L pneumophila as a historic nonproblem for this company and to rationally advise against the need for an ongoing screening program.

Deubner, D.C.; MacCormack, J.N.; Kleeman, K.; Muhlbaier, L.H.

1986-08-01

137

The Impact of the Developmental Timing of Trauma Exposure on PTSD Symptoms and Psychosocial Functioning Among Older Adults  

PubMed Central

The present study examined the impact of the developmental timing of trauma exposure on post-traumatic stress disorder (PTSD) symptoms and psychosocial functioning in a large sample of community-dwelling older adults (n = 1,995). Specifically, we investigated whether the negative consequences of exposure to traumatic events were greater for traumas experienced during childhood, adolescence, young adulthood, midlife, or older adulthood. Each of these developmental periods is characterized by age-related changes in cognitive and social processes that may influence psychological adjustment following trauma exposure. Results revealed that older adults who experienced their currently most distressing traumatic event during childhood exhibited more severe symptoms of PTSD and lower subjective happiness compared to older adults who experienced their most distressing trauma after the transition to adulthood. Similar findings emerged for measures of social support and coping ability. The differential effects of childhood compared to later life traumas were not fully explained by differences in cumulative trauma exposure or by differences in the objective and subjective characteristics of the events. Our findings demonstrate the enduring nature of traumatic events encountered early in the life course and underscore the importance of examining the developmental context of trauma exposure in investigations of the long-term consequences of traumatic experiences. PMID:23458662

Ogle, Christin M.; Rubin, David C.; Siegler, Ilene C.

2013-01-01

138

Exposure time versus concentration in the WHO standard test for mosquito resistance to chlorohydrocarbon insecticides*  

PubMed Central

In order that the WHO standard test for mosquitos may yield a median lethal dose value (LC50) in the case of highly tolerant species and resistant strains, it is necessary to increase the exposure period. The experiments described in this paper, done with a DDT-tolerant strain of Culex pipiens fatigans, show that doubling the exposure period has the same effect as doubling the DDT concentration, since it doubles the uptake of DDT into the mosquitos, and has the result of halving the LC50 obtained. PMID:5306721

Ariaratnam, V.; Brown, A. W. A.

1969-01-01

139

Time-dependent inhibition of Na+/K+-ATPase induced by single and simultaneous exposure to lead and cadmium  

NASA Astrophysics Data System (ADS)

Time-dependent interactions of Na+/K+-ATPase, isolated from rat brain synaptic plasma membranes (SPMs), with Cd2+ and Pb2+ ions in a single exposure and in a mixture were investigated in vitro. The interference of the enzyme with these metal ions was studied as a function of different protein concentrations and exposure time. The aim of the work was to investigate the possibility of selective recognition of Cd2+ and Pb2+ ions in a mixture, on the basis of the different rates of their protein-ligand interactions. Decreasing protein concentration increased the sensitivity of Na+/K+-ATPase toward both metals. The selectivity in protein-ligand interactions was obtained by variation of preincubation time (incubation before starting the enzymatic reaction).

Vasi?, V.; Koji?, D.; Krinulovi?, K.; ?olovi?, M.; Vuja?i?, A.; Stoji?, D.

2007-09-01

140

?Estimating Regional Background Air Quality using Space/Time Ordinary Kriging to Support Exposure Studies?  

EPA Science Inventory

Local-scale dispersion models are increasingly being used to perform exposure assessments. These types of models, while able to characterize local-scale air quality at increasing spatial scale, however, lack the ability to include background concentration in their overall estimat...

141

Social behavior of juvenile rats after in utero exposure to morphine: dose–time–effect relationship  

Microsoft Academic Search

In the present study, the effects of morphine exposure in utero on social behavior in juvenile male rats was investigated. Pinning, a measure for play behavior, and social grooming of the offspring were measured at postnatal day 21. The subjects were offspring of Wistar rat dams given sc. injections of 1 or 10 mg\\/kg body weight morphine HC1 daily from

Raymond J. M. Niesink; Liesbeth van Buren-van Duinkerken; Jan M. van Ree

1999-01-01

142

Effect of exposure time on the sorption of pesticide emulsifiable concentrates through microporous fabrics  

Microsoft Academic Search

applications and handlers has been a topic of concern for over two decades. Research conducted by Maibach (1971) indicates that dermal sorption could account for up to 87% of the total sorption by the human body. AI though researcher s have proved that use of protective clotbing can reduce dermal exposure, there is stil 1 a need for clothing that

Anugrah Shaw; Kenneth R. Hill

1991-01-01

143

Task- and Time-Dependent Weighting Factors in a Retrospective Exposure Assessment of Chemical Laboratory Workers  

SciTech Connect

Results are reported from a chemical exposure assessment that was conducted for a cohort mortality study of 6157 chemical laboratory workers employed between 1943 and 1998 at four Department of Energy sites in Oak Ridge, Tenn., and Aiken, S.C.

Scott A. Henn, David F. Utterback, Kathleen M. Waters, Andrea M. Markey, William G. Tankersley

2007-02-01

144

Night-time decibel hell: mapping noise exposure zones and individual annoyance ratings in an urban environment in ghana.  

PubMed

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

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

2014-01-01

145

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

PubMed

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

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

2006-01-01

146

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

PubMed Central

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

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

2014-01-01

147

Direct and indirect tasks on assessment of dose and time distributions and thresholds of acute radiation exposure.  

PubMed

Mathematical methods were developed to construct dose and time distributions and their associated risks and threshold values for lethal and non-lethal effects of acute radiation exposure to include mortality and incidence, prodromal vomiting, and agranulocytosis. A new distribution (T-model) was obtained to describe time parameters of acute radiation syndrome such as the latency period, time to onset of vomiting, and time to initiation of agranulocytosis. Based on the dose and time distributions, the parameter translation method was defined using an orthogonal regression, which allows one to solve for these distributions in the case of acute radiation exposure. The assessment of threshold doses was performed for some effects of acute radiation syndrome: for the latency period, ?6-8 Gy absorbed dose and ?0.7-0.9 h time to onset of vomiting; and for incidence (agranulocytosis), ?2-3 Gy absorbed dose and ?2-3 h time to onset of vomiting. The obtained new formula for assessment of radiation risk is applicable to the time parameters of acute radiation syndrome. PMID:22217591

Osovets, S V; Azizova, T V; Day, R D; Wald, N; Moseeva, M B

2012-02-01

148

Effect of reduced exposure times on the cytotoxicity of resin luting cements cured by high-power led  

PubMed Central

Objective Applications of resin luting agents and high-power light-emitting diodes (LED) light-curing units (LCUs) have increased considerably over the last few years. However, it is not clear whether the effect of reduced exposure time on cytotoxicity of such products have adequate biocompatibility to meet clinical success. This study aimed at assessing the effect of reduced curing time of five resin luting cements (RLCs) polymerized by high-power LED curing unit on the viability of a cell of L-929 fibroblast cells. Material and Methods Disc-shaped samples were prepared in polytetrafluoroethylene moulds with cylindrical cavities. The samples were irradiated from the top through the ceramic discs and acetate strips using LED LCU for 20 s (50% of the manufacturer's recommended exposure time) and 40 s (100% exposure time). After curing, the samples were transferred into a culture medium for 24 h. The eluates were obtained and pipetted onto L-929 fibroblast cultures (3x104 per well) and incubated for evaluating after 24 h. Measurements were performed by dimethylthiazol diphenyltetrazolium assay. Statistical significance was determined by two-way ANOVA and two independent samples were compared by t-test. Results Results showed that eluates of most of the materials polymerized for 20 s (except Rely X Unicem and Illusion) reduced to a higher extent cell viability compared to samples of the same materials polymerized for 40 s. Illusion exhibited the least cytotoxicity for 20 s exposure time compared to the control (culture without samples) followed by Rely X Unicem and Rely X ARC (90.81%, 88.90%, and 83.11%, respectively). For Rely X ARC, Duolink and Lute-It 40 s exposure time was better (t=-1.262 p=0,276; t=-9.399 p=0.001; and t=-20.418 p<0.001, respectively). Conclusion The results of this study suggest that reduction of curing time significantly enhances the cytotoxicity of the studied resin cement materials, therefore compromising their clinical performance. PMID:21625748

ERGUN, Gulfem; EGILMEZ, Ferhan; YILMAZ, Sukran

2011-01-01

149

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

PubMed

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

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

2014-01-15

150

Duration and direction of optokinetic after-nystagmus as a function of stimulus exposure time in the monkey  

Microsoft Academic Search

1.Parameters of the optokinetic after-nystagmus (OKAN) outlasting optokinetic stimulation were studied in monkeys. With constant pattern velocity (60°\\/s) exposure times were varied between 2 s and 15 min.2.All monkeys showed a primary after-nystagmus moving in the same direction (OKAN I) as the preceding optokinetic nystagmus, under all conditions tested. A secondary after-nystagmus in the opposite direction (OKAN II), was only

U. Büttner; W. Waespe; V. Henn

1976-01-01

151

Exposure to air pollution in critical prenatal time windows and IgE levels in newborns.  

PubMed

The objective of this study was to analyze the mechanisms by which exposure to ambient air pollutants influences respiratory health may include altered prenatal immune development. To analyze associations between elevated cord serum Immunoglobulin E (IgE) levels and maternal air pollution exposure during each month of gestation. Total cord serum IgE was determined by the CAP system and mothers' total IgE levels by nephelometry for 459 births in the Czech Republic from May 1994 to mid-January 1997. Concentrations of polycyclic aromatic hydrocarbons (PAHs) and particulate matter <2.5 microns in diameter (PM(2.5) ) were measured in ambient air, and arithmetic means were calculated for each gestational month. Log binomial regression models were used to estimate prevalence ratios (PR) for elevated cord serum IgE (?0.9 IU/ml) adjusting for district of residence, year of birth, and in further models, for maternal IgE (a surrogate for atopy) and gestational season. Heterogeneity by maternal atopy status was evaluated for associations of air pollution and of cigarette smoke. In adjusted models, PAH and PM(2.5) exposures in the second month of gestation were each associated with a lower prevalence of elevated cord serum IgE. For an average increase of 100 ng/m(3) of PAHs, the PR was 0.69 (95% confidence interval (CI): 0.50, 0.95); for 25 ?g/m(3) increase in PM(2.5) , the PR was 0.77 (95% CI: 0.55, 1.07). Conversely, exposures later in gestation were associated with a higher prevalence of elevated cord IgE: in the fifth month, the PR for PAH exposure was 1.64 (95% CI: 1.29, 2.08), while for PM(2.5) in the sixth month, it was 1.66 (95% CI: 1.30, 2.13). In analyses stratified by maternal atopy, air pollutants were associated with altered cord serum IgE only among neonates with non-atopic mothers. Similarly, an association of cigarette smoke with elevated cord serum IgE was found only in non-atopic mothers. PAHs and PM(2.5) , constituents of both ambient air pollution and cigarette smoke, appear to influence fetal immune development, particularly among infants whose mothers are not atopic. PMID:20609135

Herr, Caroline E W; Ghosh, Rakesh; Dostal, Miroslav; Skokanova, Venuse; Ashwood, Paul; Lipsett, Michael; Joad, Jesse P; Pinkerton, Kent E; Yap, Poh-Sin; Frost, Joshua D; Sram, Radim; Hertz-Picciotto, Irva

2011-02-01

152

Reaction time of industrial workers exposed to organic solvents: relationship to degree of exposure and psychological performance  

SciTech Connect

Auditory reaction time (RT) was examined on a day free from work and on a working day in 54 workers exposed to organic solvents and in 28 unexposed workers. Medical and occupational history was recorded and neurological examination and psychological testing carried out to establish quantitative parameters of exposure and cerebral function. There was a wider 95% range of the RT in the exposed group compared to the control group on the working day and a tendency in the same direction on the day free from work. There was no difference in the means of the RT, or within the groups between the examinations on the two days. The increased RT 95% range is interpreted as indicating an impaired ability in the exposed workers to maintain their attention during the experimental period, owing to chronic exposure of organic solvents. RT measurements did not correlate with exposure or psychological performance. RT would seem to be a means of measuring subclinical effects of exposure to organic solvents.

Gregersen, P.; Stigsby, B.

1981-01-01

153

Transcriptomic signature to oxidative stress exposure at the time of embryonic genome activation in bovine blastocysts.  

PubMed

In order to understand how in vitro culture affects embryonic quality, we analyzed survival and global gene expression in bovine blastocysts after exposure to increased oxidative stress conditions. Two pro-oxidant agents, one that acts extracellularly by promoting reactive oxygen species (ROS) production (0.01 mM 2,2'-azobis (2-amidinopropane) dihydrochloride [AAPH]) or another that acts intracellularly by inhibiting glutathione synthesis (0.4 mM buthionine sulfoximine [BSO]) were added separately to in vitro culture media from Day 3 (8-16-cell stage) onward. Transcriptomic analysis was then performed on resulting Day-7 blastocysts. In the literature, these two pro-oxidant conditions were shown to induce delayed degeneration in a proportion of Day-8 blastocysts. In our experiment, no morphological difference was visible, but AAPH tended to decrease the blastocyst rate while BSO significantly reduced it, indicating a differential impact on the surviving population. At the transcriptomic level, blastocysts that survived either pro-oxidant exposure showed oxidative stress and an inflammatory response (ARRB2), although AAPH induced higher disturbances in cellular homeostasis (SERPINE1). Functional genomics of the BSO profile, however, identified differential expression of genes related to glycine metabolism and energy metabolism (TPI1). These differential features might be indicative of pre-degenerative blastocysts (IGFBP7) in the AAPH population whereas BSO exposure would select the most viable individuals (TKDP1). Together, these results illustrate how oxidative disruption of pre-attachment development is associated with systematic up-regulation of several metabolic markers. Moreover, it indicates that a better capacity to survive anti-oxidant depletion may allow for the survival of blastocysts with a quieter metabolism after compaction. PMID:23426876

Cagnone, Gael L M; Sirard, Marc-André

2013-04-01

154

Timing of Moderate Level Prenatal Alcohol Exposure Influences Gene Expression of Sensory Processing Behavior in Rhesus Monkeys  

PubMed Central

Sensory processing disorder, characterized by over- or under-responsivity to non-noxious environmental stimuli, is a common but poorly understood disorder. We examined the role of prenatal alcohol exposure, serotonin transporter gene polymorphic region variation (rh5-HTTLPR), and striatal dopamine (DA) function on behavioral measures of sensory responsivity to repeated non-noxious sensory stimuli in macaque monkeys. Results indicated that early gestation alcohol exposure induced behavioral under-responsivity to environmental stimuli in monkeys carrying the short (s) rh5-HTTLPR allele compared to both early-exposed monkeys homozygous for the long (l) allele and monkeys from middle-to-late exposed pregnancies and controls, regardless of genotype. Moreover, prenatal timing of alcohol exposure altered the relationship between sensory scores and DA D2R availability. In early-exposed monkeys, a positive relationship was shown between sensory scores and DA D2R availability, with low or blunted DA function associated with under-responsive sensory function. The opposite pattern was found for the middle-to-late gestation alcohol-exposed group. These findings raise questions about how the timing of prenatal perturbation and genotype contributes to effects on neural processing and possibly alters neural connections. PMID:19936317

Schneider, Mary L.; Moore, Colleen F.; Larson, Julie A.; Barr, Christina S.; DeJesus, Onofre T.; Roberts, Andrew D.

2009-01-01

155

Experimental investigation of the effect of stiffness, exposure time and scan direction on the dimension of ultrasound histotripsy lesions.  

PubMed

Histotripsy uses high-intensity focused ultrasound to create energetic bubble clouds inside tissue to liquefy a region and has the advantages of higher contrast B-mode monitoring and sharp borders. This study experimentally investigated the effects of stiffness, exposure time and scan direction on the size of histotripsy-induced lesions in agar samples. A targeted region 0.45 cm wide (lateral) and 0.6 cm deep (axial) was scanned with the step sizes of 0.075 cm and 0.3 cm, respectively. The single-element spherically focused source (1.1 MHz, 6.34 cm focal length, f/1) had the peak compressional and rarefactional pressures of approximately 102 and 17 MPa. Pulses consisted of 20-cycle sine wave tone bursts with a burst period of 3 ms and exposure time of 15, 30 or 60 s. Also, both inward and outward scan direction were tested along the beam axis. The liquefied lesions generally had a larger size than the initially targeted region with larger sizes corresponding to softer agar and longer exposure. There was not a statistically significant difference in the lesion size with scan direction. PMID:21963031

Xu, Jin; Bigelow, Timothy A

2011-11-01

156

Post-Exposure Sleep Deprivation Facilitates Correctly Timed Interactions Between Glucocorticoid and Adrenergic Systems, which Attenuate Traumatic Stress Responses  

PubMed Central

Reliable evidence supports the role of sleep in learning and memory processes. In rodents, sleep deprivation (SD) negatively affects consolidation of hippocampus-dependent memories. As memory is integral to post-traumatic stress symptoms, the effects of post-exposure SD on various aspect of the response to stress in a controlled, prospective animal model of post-traumatic stress disorder (PTSD) were evaluated. Rats were deprived of sleep for 6?h throughout the first resting phase after predator scent stress exposure. Behaviors in the elevated plus-maze and acoustic startle response tests were assessed 7 days later, and served for classification into behavioral response groups. Freezing response to a trauma reminder was assessed on day 8. Urine samples were collected daily for corticosterone levels, and heart rate (HR) was also measured. Finally, the impact of manipulating the hypothalamus–pituitary–adrenal axis and adrenergic activity before SD was assessed. Mifepristone (MIFE) and epinephrine (EPI) were administered systemically 10-min post-stress exposure and behavioral responses and response to trauma reminder were measured on days 7–8. Hippocampal expression of glucocorticoid receptors (GRs) and morphological assessment of arborization and dendritic spines were subsequently evaluated. Post-exposure SD effectively ameliorated long-term, stress-induced, PTSD-like behavioral disruptions, reduced trauma reminder freezing responses, and decreased hippocampal expression of GR compared with exposed-untreated controls. Although urine corticosterone levels were significantly elevated 1?h after SD and the HR was attenuated, antagonizing GRs with MIFE or stimulation of adrenergic activity with EPI effectively abolished the effect of SD. MIFE- and EPI-treated animals clearly demonstrated significantly lower total dendritic length, fewer branches and lower spine density along dentate gyrus dendrites with increased levels of GR expression 8 days after exposure, as compared with exposed-SD animals. Intentional prevention of sleep in the early aftermath of stress exposure may well be beneficial in attenuating traumatic stress-related sequelae. Post-exposure SD may disrupt the consolidation of aversive or fearful memories by facilitating correctly timed interactions between glucocorticoid and adrenergic systems. PMID:22713910

Cohen, Shlomi; Kozlovsky, Nitsan; Matar, Michael A; Kaplan, Zeev; Zohar, Joseph; Cohen, Hagit

2012-01-01

157

Effects of incubation humidity and hatching time on heat tolerance of neonatal chicks: growth performance after heat exposure.  

PubMed

Three experiments were performed with 300 neonatal Hisex Brown layer chicks in each. The chicks hatched from eggs incubated at a relative humidity (RH) of 55 or 45%. Within each RH group, two groups were separated based on hatching time (early and late hatch groups). After hatch, 60 chicks served as controls. The other chicks were exposed to 35, 37, or 39 C for 48 h. After exposure, a 4-wk experimental growing period started at Day 2 of age. Chicks exposed to the experimental temperature regimens for 2 days had lower body weights at the end of exposure and grew less than controls during the 1st wk afterwards. At Day 2 of age, chicks hatched from eggs incubated at 45% RH had higher body weights than chicks hatched from eggs incubated at 55% RH. These chicks also had higher body weight gain in the 1st and 2nd wk following exposure to 39 C than chicks hatched from eggs incubated at 55% RH. Chicks hatching late were heavier at Day 2 than early-hatching ones, but body weight gain was similar. Chicks exposed to the experimental temperature regimens had lower rectal temperatures than controls at the end of the 1st and 2nd wk. Incubation RH, hatching time, and sex did not affect feed intake, feed conversion, or rectal temperature. After exposure to 39 C, fewer chicks that had hatched from eggs incubated at low RH died compared with chicks that had hatched from the 55% RH group. Early-hatching chicks had a significantly higher risk of dying than late-hatching ones. PMID:1886861

Hamdy, A M; Henken, A M; Van der Hel, W; Galal, A G; Abd-Elmoty, A K

1991-07-01

158

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

PubMed

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

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

2014-12-01

159

Germination Response of MR 219 Rice Variety to Different Exposure Times and Periods of 2450 MHz Microwave Frequency  

PubMed Central

Germination is a key process in plants' phenological cycles. Accelerating this process could lead to improvment of the seedling growth as well as the cultivation efficiency. To achieve this, the effect of microwave frequency on the germination of rice seeds was examined. The physiological feedbacks of the MR 219 rice variety in terms of seed germination rate (GR), germination percentage (GP), and mean germination time (MGT) were analyzed by exposing its seeds to 2450?MHz of microwave frequency for one, four, seven, and ten hours. It was revealed that exposing the seeds to the microwave frequency for 10 hours resulted in the highest GP. This treatment led to 100% of germination after three days with a mean germination time of 2.1 days. Although the other exposure times of microwave frequency caused the moderate effects on germination with a GPa3 ranged from 93% to 98%, they failed to reduce the MGTa3. The results showed that ten-hour exposure times of microwave frequency for six days significantly facilitated and improved the germination indices (primary shoot and root length). Therefore, the technique is expected to benefit the improvement of rice seed germination considering its simplicity and efficacy in increasing the germination percentage and rate as well as the primary shoot and root length without causing any environmental toxicity. PMID:24307869

Valdiani, Alireza; Maziah, Mahmood; Mohsenkhah, Mohammad

2013-01-01

160

Germination response of MR 219 rice variety to different exposure times and periods of 2450 MHz microwave frequency.  

PubMed

Germination is a key process in plants' phenological cycles. Accelerating this process could lead to improvment of the seedling growth as well as the cultivation efficiency. To achieve this, the effect of microwave frequency on the germination of rice seeds was examined. The physiological feedbacks of the MR 219 rice variety in terms of seed germination rate (GR), germination percentage (GP), and mean germination time (MGT) were analyzed by exposing its seeds to 2450 MHz of microwave frequency for one, four, seven, and ten hours. It was revealed that exposing the seeds to the microwave frequency for 10 hours resulted in the highest GP. This treatment led to 100% of germination after three days with a mean germination time of 2.1 days. Although the other exposure times of microwave frequency caused the moderate effects on germination with a GP(a3) ranged from 93% to 98%, they failed to reduce the MGT(a3). The results showed that ten-hour exposure times of microwave frequency for six days significantly facilitated and improved the germination indices (primary shoot and root length). Therefore, the technique is expected to benefit the improvement of rice seed germination considering its simplicity and efficacy in increasing the germination percentage and rate as well as the primary shoot and root length without causing any environmental toxicity. PMID:24307869

Talei, Daryush; Valdiani, Alireza; Maziah, Mahmood; Mohsenkhah, Mohammad

2013-01-01

161

A time to tan: proximal and distal effects of mortality salience on sun exposure intentions.  

PubMed

According to the dual defense model of terror management, proximal defenses are engaged to reduce the conscious impact of mortality salience, whereas thoughts of death outside of conscious awareness motivate distal defenses aimed at maintaining self-esteem. Two experiments examined these ideas by assessing women's intentions to engage in tanning-related behavior. In Study 1, when concerns about death (relative to dental pain) were in focal attention, participants increased intentions to protect themselves from dangerous sun exposure. In contrast, when thoughts about death were outside of focal attention, participants decreased interest in sun protection. In Study 2, participants primed to associate tanned skin with an attractive appearance responded to mortality concerns outside of focal attention with increased interest in tanning products and services. These findings are discussed in relation to the dual-defense model of terror management, societal determinants of self-esteem, and implications for health risk and promotion. PMID:15466606

Routledge, Clay; Arndt, Jamie; Goldenberg, Jamie L

2004-10-01

162

Is Television Viewing Associated With Social Isolation? Roles of Exposure Time, Viewing Context, and Violent Content  

Microsoft Academic Search

Results: Viewing violent programs (but not nonviolent programs) was negatively related to time children spent with friends (aged 6-8 years, unstandardized regression coefficient () =?0 .34, 95% confidence interval (CI), ?0 .59 to ?0 .08; aged 9-12 years, = ?0 .41, 95% CI,?0.65 to?0.18). More time viewing television with friends was associated with more time engaging in other activities with

David S. Bickham; Michael Rich

2006-01-01

163

Comparison of time to PRRSv-stability and production losses between two exposure programs to control PRRSv in sow herds.  

PubMed

To control and eliminate porcine reproductive and respiratory syndrome virus (PRRSv) from breeding herds, some veterinarians adopt a strategy called load-close-expose which consists of interrupting replacement pig introduction for several months and exposing the pigs to a replicating PRRSv. This was a prospective quasi-experiment that followed 61 breeding herds acutely infected with PRRSv that adopted one of two exposure programs: modified-live virus (MLV) vaccine or live-resident virus inoculation (LVI). Treatment groups (load-close-expose with MLV or LVI) were compared for: (a) time-to-PRRSv stability (TTS), defined as time in weeks it took to produce PRRSv negative pigs at weaning; (b) the time-to-baseline production (TTBP), defined using statistical process control methods to represent time to recover to the number of pigs weaned per week that herds had prior to PRRSv-detection; and (c) the total production loss in terms of number of pigs weaned per week. TTS and TTBP were compared between treatments using survival analysis. Day 1 of the program was considered to be the day that treatment was administered. Sampling at herds consisted of bleeding 30 due-to-wean piglets on a monthly basis. Serum was tested for PRRSv RNA by RT-PCR. Herds in which PRRSv was not detected over a 90-day period were classified as reaching stability. Multivariate analysis using proportional hazards regression was performed adjusting the effect of treatment on TTBP and TTS to 'severity of PRRSv infection', 'number of whole-herd exposures', 'days from PRRSv-detection to intervention', 'prior PRRSv-infection status' and 'veterinary clinic associated with the herd'. Total loss was compared between groups using multivariate regression analysis adjusted by selected covariates. The median TTS among participating herds was 26.6 weeks (25th to 75th percentile, 21.6-33.0 weeks). The overall TTBP was 16.5 weeks (range 0-29 weeks). The magnitude of production losses following whole-herd exposure averaged 2217 pigs not weaned/1000 sows and was correlated with TTBP. Herds in the MLV group recovered production sooner and had less total loss than herds in the LVI group. TTBP and TTS were significantly shorter and the total loss was significantly less in herds assisted by a specific veterinary clinic and herds that were infected with PRRSv in the 3 years prior to the study. This study provided new metrics to assist veterinarians to decide between methods of exposure to control and eliminate PRRSv from breeding herds. PMID:24931129

Linhares, D C L; Cano, J P; Torremorell, M; Morrison, R B

2014-09-01

164

Electron microscopy and microanalysis of steel weld joints after long time exposures at high temperatures  

NASA Astrophysics Data System (ADS)

The structural changes of three trial weld joints of creep resistant modified 9Cr-1Mo steels and low alloyed chromium steel after post-weld heat treatment and long-term creep tests were investigated. Smooth cross-weld specimens ruptured in different zones of the weld joints as a result of different structural changes taking place during creep exposures. The microstructure of the weld joint is heterogeneous and consequently microstructural development can be different in the weld metal, the heat affected zone, and the base material. Precipitation reactions, nucleation and growth of some particles and dissolution of others, affect the strengthening of the matrix, recovery at high temperatures, and the resulting creep resistance. Therefore, a detailed study of secondary phase's development in individual zones of weld joints can elucidate mechanism of cracks propagation in specific regions and the causes of creep failure. Type I and II fractures in the weld metal and Type IV fractures in the fine prior austenite grain heat affected zones occurred after creep tests at temperatures ranging from 525 to 625 °C and under stresses from 40 to 240 MPa. An extended metallographic study of the weld joints was carried out using scanning and transmission electron microscopy, energy-dispersive and wave-dispersive X-ray microanalysis. Carbon extraction replicas and thin foils were prepared from individual weld joint regions and quantitative evaluation of dislocation substructure and particles of secondary phases has been performed.

Jandová, D.; Kasl, J.; Rek, A.

2010-02-01

165

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

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…

Spano, Richard; Rivera, Craig; Bolland, John

2006-01-01

166

IMPLICATIONS OF USING AMBIENT PM CONCENTRATION AS A SURROGATE FOR PM EXPOSURE IN STATISTICAL AND EPIDEMIOLOGIC ANALYSES OF TIME SERIES DATA  

EPA Science Inventory

The question What information may be obtained from a time-series regression of health effects on ambient PM concentration?, is of interest to exposure analysts and epidemiologists, especially since exposure analysts find low and frequently non-significant correlations betw...

167

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

Microsoft Academic Search

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.

Anna Lindgren; Jonas Björk; Emilie Stroh; Kristina Jakobsson

2010-01-01

168

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

E-print Network

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 ...

Crane, Riley

169

Response of Vibrio fischeri to repeated exposures over time in an Online Toxicity Monitor  

EPA Science Inventory

Online Toxicity Monitors have been developed to provide continuous, time-relevant information regarding water quality. These systems measure a physiological or behavioral response of a sentinel organism to changes water quality. One such system, the Microlan Toxcontrol, is base...

170

The effect of cold exposure of sheep on digestion, rumen turnover time and efficiency of microbial synthesis.  

PubMed

1. Six closely shorn sheep were given brome grass (Bromus inermis) pellets at 1 h intervals and maintained at ambient temperatures of --I to Idegree and 18--21degrees for 28 d. Measurements of digestion were made during the last 10 d of temperature exposure. 2. Cold exposure resulted in a reduction in apparent dry matter (DM) digestibility from 0-482 to 0-450, and of apparent digestibility of organic matter (OM) from 0-511 to 0-477. Neither apparent digestibility nor retention of nitrogen was affected. 3. Apparent digestibility of OM in the rumen decreased from 0-300 to 0-242 with cold exposure, and was highly correlated with turnover time in the rumen of 103Ru, which was used as a particulate marker. 4. The efficiency of microbial synthesis (g N incorporated into microbial cells/kg OM apparently digested) was correlated with the dilution rate of the solute marker (51Cr) and with the turnover time of the particulate marker (103Ru) in the rumen. 5. Digestion in the intestine of DM and OM accounted for significantly more of apparent digestion in the whole gastrointestinal tract for sheep kept in the cold than for sheep kept in the warm. The apparent digestibilities of DM and OM entering the intestine were similar in sheep on both treatments, but significantly more non-ammonia-N was digested in the intestines of cold-exposed sheep. 6. The influence of dilution rate of rumen fluid on the efficiency of synthesis of microbial cells in the rumen is discussed. PMID:952836

Kennedy, P M; Christopherson, R J; Milligan, L P

1976-09-01

171

On the time course, generality, and regulation of plasma progesterone release in male rats by stress exposure.  

PubMed

Although progesterone is most commonly regarded in terms of its role in the female estrous cycle, reproductive behavior, and pregnancy, progesterone is also a precursor to corticosterone (CORT) and is released from the adrenal glands of both sexes in response to stress. However, the relationship between plasma CORT and progesterone during times of stress has not been well established. To better characterize dynamic changes in progesterone release as a result of stressor exposure, plasma progesterone levels were measured using enzyme immunoassay under multiple conditions, including after stress exposure (footshock, restraint, and forced swim), manipulations of the hypothalamic-pituitary-adrenal axis (injection of metyrapone or dexamethasone, or adrenalectomy), and in response to CRH and ACTH injections. When plasma levels of ACTH, CORT, and progesterone were analyzed across studies, CORT and progesterone were found to be highly correlated and rarely dissociated. Additionally, it appears that in male rats, the adrenal glands are the principle source of circulating progesterone in response to stress. Interestingly, a detailed time course indicated lack of a circadian rhythm of progesterone secretion, despite a robust rhythm of circulating CORT. The current studies provide critical new information on the coincident release of progesterone and CORT in response to stress and their somewhat paradoxical dissociation across the circadian rhythm. These findings provide an important foundation for future studies that will examine the role of stress-induced progesterone in behavioral, neuroimmune, and neuroendocrine responses to stress. PMID:24926824

Hueston, Cara M; Deak, Terrence

2014-09-01

172

Mitigating Information Exposure to Cheaters in Real-Time Strategy Games  

E-print Network

such as Half-life, Lineage, and Warcraft record hundreds of thousands of players per day. Cheating in on and players. The popular real-time strategy game genre is especially vulnerable to cheats, as it is fre Association (IDSA) 2004 report cites half of all Americans aging six and older as video game players

173

DNA methylation differences after exposure to prenatal famine are common and timing- and sex-specific  

Microsoft Academic Search

Prenatal famine in humans has been associated with various later-life consequences depending on the gestational timing of the insult and the sex of the exposed individual. Epigenetic mechanisms have been proposed to underlie these associations. Indeed, animal studies and our early human data on the imprinted IGF2 locus indicated a link between prenatal nutritional and DNA methylation. However, it remains

Elmar W. Tobi; L. H. Lumey; Rudolf P. Talens; Dennis Kremer; Hein Putter; Aryeh D. Stein; P. E. Slagboom; Bastiaan T. Heijmans

2009-01-01

174

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

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

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

2014-11-01

175

Long-term exposure to mobile communication radiation: an analysis of time-variability of electric field level in GSM900 downlink channels.  

PubMed

Interest for knowing long-term human exposure levels due to mobile communications has increased in the last years. It has been shown that short-term exposure assessment made under standard procedural restrictions is not reliable when it comes to conclusions on long-term exposure levels. The present work is the result of a several week analysis of time variability of electric field level inside traffic and control channels of the GSM900 mobile communication downlink band and it indicates that a temporal model to allow future predictions of exposure on the long run is obtainable. Collecting, processing and statistically analysing the data provide expression of the maximum and weighted field strengths and their evolution in time. Specific electromagnetic footprints of the channels have been extracted, differentiations between their characteristics have been emphasised and practical advice is provided, with the scope of contributing to the development of reliable procedures for long-term exposure assessment. PMID:22908352

Miclaus, Simona; Bechet, Paul; Gheorghevici, Marius

2013-04-01

176

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

USGS Publications Warehouse

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.

Wood, Nathan J.; Schmidtlein, Mathew C.

2013-01-01

177

Timing of terminal Pleistocene deglaciation at high elevations in southern and central British Columbia constrained by 10Be exposure dating  

NASA Astrophysics Data System (ADS)

The Cordilleran Ice Sheet (CIS) covered most of British Columbia and southern Yukon Territory at the local Last Glacial Maximum (lLGM) during Marine Oxygen Isotope Stage 2. However, its subsequent demise is not well understood, particularly at high elevations east of its ocean-terminating margin. We present 10Be exposure ages from two high-elevation sites in southern and central British Columbia that help constrain the time of initial deglaciation at these sites. We sampled granodiorite erratics at elevations of 2126-2230 m a.s.l. in the Marble Range and 1608-1785 m a.s.l. in the Telkwa Range at the western margin of the Interior Plateau. The erratics at both sites are near ice-marginal meltwater channels that delineate the local ice surface slope and thus the configuration of the ice sheet during deglaciation. The locations of the erratics and their relations to meltwater channels ensure that the resulting 10Be ages date CIS deglaciation and not the retreat of local montane glaciers. Our sample sites emerged above the surface of the CIS as its divide migrated westward from the Interior Plateau to the axis of the Coast Mountains. Two of the four samples from the summit area of the Marble Range yielded apparent exposure ages of 14.0 ± 0.7 and 15.2 ± 0.8 ka. These ages are 1.8-3.0 ka younger than the well-established lLGM age of ca 17 ka for the Puget lobe of the CIS in Washington State; they are 1.7 ka younger than the lLGM age for the Puget lobe if a snow-shielding correction to their uncertainty-weighted mean age is applied. The other two samples yielded much older apparent exposure ages (20.6 ± 1.4 and 33.0 ± 1.5 ka), indicating the presence of inherited isotopes. Four samples collected from the summit area of the Telkwa Range in the Hazelton Mountains yielded well clustered apparent exposure ages of 10.1 ± 0.6, 10.2 ± 0.7, 10.4 ± 0.5, and 11.5 ± 1.1 ka. Significant present-day snow cover introduces a large uncertainty in the apparent exposure ages from this site. A snow-shielding correction based on present-day snow cover data increases the uncertainty-weighted mean exposure age of the Telkwa Range erratics to 12.4 ± 0.7 ka, consistent with deglacial 14C ages from areas near sea level to the west. Our exposure ages show a thinning of the southern portion of the CIS shortly after the lLGM and persistence of a remnant mountain ice cap in the central Coast Mountains into the Younger Dryas Chronozone. Our data also show that the summit area of the Marble Range was ice-covered during the lLGM. The presence of an ice body of considerable dimension in north-central British Columbia until, or possibly even after, the Younger Dryas highlights the need for geomorphological and geochronological studies of the ice dispersal centre over the Skeena Mountains in northwest British Columbia and the need for better understanding of the response of the CIS to Lateglacial climate fluctuations.

Margold, Martin; Stroeven, Arjen P.; Clague, John J.; Heyman, Jakob

2014-09-01

178

Ozone exposure and daily mortality in Mexico City: a time-series analysis.  

PubMed

Daily death counts in Mexico City were examined in relation to ambient ozone levels during 1990-1992 for the purpose of investigating the acute, irreversible effects of air pollution, with emphasis on ozone exposure. Air pollution data were obtained from nine monitoring stations operated by the Departamento del Distrito Federal. Mortality data were provided by the Instituto Nacional de Estadística, Geografía, e Informática. Increases in numbers of deaths were positively associated with elevated air pollution levels on the same day and on the previous day. The magnitude of the increases was small but statistically significant, after Poisson regression models were used to adjust for temperature and long-term trends. In models using data for a single pollutant, the "crude" ratio for total mortality associated with an increase of 100 parts per billion (ppb)* in one-hour maximum ozone concentration was 1.029 (95% CI 1.015, 1.044). A moving average of ozone showed a stronger association (rate ratio [RR] = 1.048, 95% CI 1.025, 1.070), and excess mortality (an increase in the number of deaths, relative to the average on days with low pollution levels) was more evident for persons over 65 years of age. Separate analyses of the effect of elevated ozone for different areas of the city showed similar results, but they were not statistically significant. Other pollutants also were related to mortality. The RR was 1.075 (95% CI 0.984, 1.062) per 100-ppb increase for sulfur dioxide and 1.049 (95% CI 1.030, 1.067) per 100 micrograms/m3 increase in total suspended particulates (TSP) when these pollutants were considered in separate models. However, when all three pollutants were considered simultaneously, only TSP remained associated with mortality, indicating excess mortality of 5% per 100 micrograms/m3 increase [RR = 1.052, 95% CI 1.034, 1.072]. The excess mortality associated with TSP is consistent with that observed in other cities in America and Europe. This study provides some evidence that ozone is associated with all-cause mortality and with mortality among the elderly after controlling for long-term cycles. However, ozone levels exhibited little or no effect on mortality rates when other air pollutants were considered simultaneously. Particulate matter appeared to be an important pollutant; it independently predicted changes in mortality. Nevertheless, because of the complexity and variability of the mixtures to which people are exposed, it is difficult to attribute the observed effects to a single pollutant. The technical feasibility and scientific validity of isolating the effect of single pollutants in such complex mixtures requires further research and careful consideration. Given the large population living in and exposed to ambient air pollution in Mexico City and other metropolises throughout the world, these small but significant associations of mortality with air pollution indices are of public health concern. PMID:8916289

Loomis, D P; Borja-Aburto, V H; Bangdiwala, S I; Shy, C M

1996-10-01

179

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

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

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

2014-07-01

180

Positional error and time-activity patterns in near-highway proximity studies: an exposure misclassification analysis  

PubMed Central

Background The growing interest in research on the health effects of near-highway air pollutants requires an assessment of potential sources of error in exposure assignment techniques that rely on residential proximity to roadways. Methods We compared the amount of positional error in the geocoding process for three different data sources (parcels, TIGER and StreetMap USA) to a “gold standard” residential geocoding process that used ortho-photos, large multi-building parcel layouts or large multi-unit building floor plans. The potential effect of positional error for each geocoding method was assessed as part of a proximity to highway epidemiological study in the Boston area, using all participants with complete address information (N?=?703). Hourly time-activity data for the most recent workday/weekday and non-workday/weekend were collected to examine time spent in five different micro-environments (inside of home, outside of home, school/work, travel on highway, and other). Analysis included examination of whether time-activity patterns were differentially distributed either by proximity to highway or across demographic groups. Results Median positional error was significantly higher in street network geocoding (StreetMap USA?=?23 m; TIGER?=?22 m) than parcel geocoding (8 m). When restricted to multi-building parcels and large multi-unit building parcels, all three geocoding methods had substantial positional error (parcels?=?24 m; StreetMap USA?=?28 m; TIGER?=?37 m). Street network geocoding also differentially introduced greater amounts of positional error in the proximity to highway study in the 0–50 m proximity category. Time spent inside home on workdays/weekdays differed significantly by demographic variables (age, employment status, educational attainment, income and race). Time-activity patterns were also significantly different when stratified by proximity to highway, with those participants residing in the 0–50 m proximity category reporting significantly more time in the school/work micro-environment on workdays/weekdays than all other distance groups. Conclusions These findings indicate the potential for both differential and non-differential exposure misclassification due to geocoding error and time-activity patterns in studies of highway proximity. We also propose a multi-stage manual correction process to minimize positional error. Additional research is needed in other populations and geographic settings. PMID:24010639

2013-01-01

181

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

PubMed Central

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

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

2012-01-01

182

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

PubMed Central

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

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

2014-01-01

183

Developmental timing and continuity of exposure to interparental violence and externalizing behavior as prospective predictors of dating violence.  

PubMed

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 the continuity of externalizing behavior are critical risks for the intergenerational transmission of dating violence. The 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

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

2013-11-01

184

Short-term neonatal/prepubertal exposure of dibutyl phthalate (DBP) advanced pubertal timing and affected hypothalamic kisspeptin/GPR54 expression differently in female rats.  

PubMed

Dibutyl phthalate (DBP) had been widely used and its exposure in children has been thought to be one of the reasons causing a trend of advanced pubertal timing in girls. Puberty starts from hypothalamic gonadotropin-releasing hormone release which is controlled by many factors including neurotransmitter kisspeptin and its receptor GPR54. These neural organization or reorganization happens in hypothalamus during neonatal or prepubertal period which may be two target windows of DBP exposure. The present study was designed to determine: (1) the difference between the effects of neonatal and prepubertal DBP exposure on female pubertal timing; (2) whether kisspeptin/GPR54 expression in hypothalamus would respond to neonatal and prepubertal DBP exposure differently. Female Sprague-Dawley rats were exposed by subcutaneous injection of 0.5, 5 and 50mg/kg DBP during Postnatal day (P)1-5 (neonatal) or P26-30 (prepubertal). Physiological data demonstrated that both neonatal and prepubertal DBP exposure could advance pubertal timing significantly accompanied by irregular estrous cycles but only a little gonadal impairment. Exposure-period-related difference was found significant with prepubertal exposure groups having longer estrous cycle duration, heavier at vaginal opening and having higher serum estradiol level compared with neonatal exposure groups. Molecular data showed an up-regulated trend in kisspeptin mRNA and immunoreactivity levels of hypothalamic area arcuate but a down-regulation in GPR54 mRNA expression after P1-5 DBP treatment. In P26-30 groups, kisspeptin mRNA and immunoreactivity levels tended to be lower after DBP treatment. These results demonstrated small dose of DBP could induce earlier pubertal timing in females and both neonatal and prepubertal periods were critical windows for DBP exposure. PMID:24056307

Hu, Jialei; Du, Guizhen; Zhang, Wei; Huang, Hongyu; Chen, Danni; Wu, Di; Wang, Xinru

2013-12-01

185

Epidermal barrier: Adverse and beneficial changes induced by ultraviolet B irradiation depending on the exposure dose and time (Review)  

PubMed Central

Exposure of the skin to ultraviolet (UV) radiation induces various harmful effects in the tissues, particularly disruption of the epidermal barrier. However, ultraviolet B (UVB) irradiation has been applied in the treatment of atopic dermatitis, a skin disease in which the epidermal barrier is defective. We reviewed the homeostasis of the epidermal barrier and several studies investigating the adverse and beneficial effects caused by different doses of UVB irradiation in the epidermal barrier. It may be concluded that, despite the harmful effects of UVB irradiation on the skin, UVB irradiation is able to exert beneficial effects in the epidermal barrier when administered in suberythemal doses and over a relatively short period of time, with no clinically evident inflammation or barrier disruption. This may be a useful therapeutic strategy for the use of UVB irradiation in the treatment of skin diseases with a disrupted epidermal barrier, such as atopic dermatitis, while reducing or avoiding the side-effects. PMID:24137176

PERMATASARI, FELICIA; ZHOU, BINGRONG; LUO, DAN

2013-01-01

186

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

PubMed Central

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

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

187

Development of the short time exposure (STE) test: an in vitro eye irritation test using SIRC cells.  

PubMed

Using SIRC (rabbit corneal cell line) cells, we developed an alternative eye irritation test: the short time exposure (STE) test. This STE test is a cytotoxicity test using physiological saline or mineral oil as the test solvent. Evaluation exposure time is short (5 min), which is similar to actual exposure situations, and uses the cell viability (CV) at a constant concentration as the endpoint for irritation potential. First, in order to confirm the usefulness of this STE test in assessing eye irritation potential of chemicals, 51 raw materials were tested and the correlation between CV in the STE test and the eye irritation score in the Draize test was examined. For the undiluted raw materials tested in the Draize test, the 5% test concentration in the STE test gave irritation classes that correlated well with the irritation classes from the Draize test (accuracy: 89.6%). For those materials tested as a 10% solution in the Draize test, STE irritation classes with 0.05% test concentration corresponded well with the Draize irritation classes (accuracy: 80.0%). Next, using the cell viabilities at these two concentrations, the STE prediction model (PM) was developed. A score of 1 or 2 was given for the results from each tested concentration in the STE test and Draize test. The scores from each test were then summed to yield a 3-level (Rank 1: minimally irritant, Rank 2: moderate irritant, Rank 3: severe irritant) eye irritation potential classification. Rank classification in the STE test showed a good correlation mostly to that in the Draize test (irritation class correspondence rate: 70.2%, but after exclusion of data of alcoholic materials, the rate was 91.7%). In most cytotoxicity test, the cytotoxicity of acids and amines is generally underestimated due the use of medium as the solvent. This is the result of the buffering capacity of the media. On the other hand, the STE test could predict the eye irritation potential by evaluating the chemical with a 5% test concentration. Eleven water insoluble materials such as toluene, octanol, and hexanol could be evaluated by using mineral oil as test solvent in the STE test. The STE test demonstrated itself to be simple, promising, have great potential, be of value, and to be an easily standardized alternative eye irritation test. PMID:18248950

Takahashi, Yutaka; Koike, Mirei; Honda, Hiroshi; Ito, Yuichi; Sakaguchi, Hitoshi; Suzuki, Hiroyuki; Nishiyama, Naohiro

2008-04-01

188

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)

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.

Nakajima, Hideaki; Miyauchi, Masaatsu; Hirai, Chizuko

2013-04-01

189

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

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

2010-01-01

190

Second-phase validation study of short time exposure test for assessment of eye irritation potency of chemicals.  

PubMed

A Short Time Exposure (STE) test is a cytotoxicity test that uses SIRC cells (rabbit corneal cell line) to assess eye irritation potency following a 5-min chemical exposure. This second-phase validation study assessed the predictive capacity of the STE test using 40 coded test substances at three laboratories. A Validation Management Team (VMT) then evaluated the predictivity of the STE test for United Nation (UN) Globally Harmonized System (GHS) categories using 63 test substances including the results of the first-phase validation study. The STE test can assess not only the severe or corrosive ocular irritants (corresponding to the UN GHS Category 1) but also non-irritant (corresponding to UN GHS Non Category) from other toxicity classes, especially for limited types of test substances. The predictivity by STE test, however, was insufficient for identification of UN GHS categories (Category 1, Category 2, or Non Category). These results suggest that the STE test can be recommended as an initial step in a top-down approach to identification of severe irritants and test substances that require classification for eye irritation (UN GHS Category 1) as well as an initial step in a bottom-up approach to identification of test substances that do not require classification for eye irritation (UN GHS Non Category) from other toxicity classes, especially for limited types of test substances. On the other hand, the STE test is not considered adequate for the identification of mild or moderate irritants (i.e., UN GHS Categories 2A and 2B) and severe irritants (UN GHS Category 1). PMID:23747838

Kojima, Hajime; Hayashi, Kazuhiko; Sakaguchi, Hitoshi; Omori, Takashi; Otoizumi, Takuya; Sozu, Takashi; Kuwahara, Hirofumi; Hayashi, Takumi; Sakaguchi, Mayumi; Toyoda, Akemi; Goto, Haruka; Watanabe, Shinichi; Ahiko, Kyoko; Nakamura, Tsuneaki; Morimoto, Takashi

2013-09-01

191

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

PubMed

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

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

2013-04-01

192

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

E-print Network

assessed according to DSM-IV criteria. Results: A significant relationship was observed between exposure 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

Paris-Sud XI, Université de

193

A week in the life of full-time office workers: Work day and weekend light exposure in summer and winter.  

PubMed

Little is known about the light exposure in full-time office workers, who spend much of their workdays indoors. We examined the 24-h light exposure patterns of 14 full-time office workers during a week in summer, and assessed their dim light melatonin onset (DLMO, a marker of circadian timing) at the end of the working week. Six workers repeated the study in winter. Season had little impact on the workers' schedules, as the timing of sleep, commute, and work did not vary by more than 30 min in the summer and winter. In both seasons, workers received significantly more morning light on workdays than weekends, due to earlier wake times and the morning commute. Evening light in the two hours before bedtime was consistently dim. The timing of the DLMO did not vary between season, and by the end of the working week, the workers slept at a normal circadian phase. PMID:25172304

Crowley, Stephanie J; Molina, Thomas A; Burgess, Helen J

2015-01-01

194

Patterns and timing of sunlight exposure and risk of basal cell and squamous cell carcinomas of the skin - a case-control study  

PubMed Central

Background Non-melanoma skin cancer (NMSC), comprised of basal (BCC) and squamous (SCC) cell carcinomas, is the most common cancer in Caucasians. Ultraviolet radiation (UVR) exposure is the most important environmental risk factor for NMSC. However, the precise relationship between UVR and the risk of NMSC is complex, and the relationship may differ by skin cancer type. Methods A case–control study was conducted among Florida residents to investigate measures of patterns (intermittent vs. continuous) and timing (childhood vs. adulthood) of sunlight exposure in BCC and SCC. Participants included 218 BCC and 169 SCC cases recruited from a university dermatology clinic and 316 controls with no history of skin or other cancers. Results A history of blistering sunburn (a measure of intermittent sunlight exposure) was associated with both BCC (OR?=?1.96, 95% CI?=?1.27-3.03) and SCC (OR?=?2.02, 95% CI?=?1.22-3.33). Additionally, having a job in the sun for ?3 months for 10 years or longer (a measure of continuous sunlight exposure) was also associated with both BCC and SCC in our study population. With the exception of younger age at first blistering sunburn, measures of younger age at sunlight exposure tended to be associated with SCC, but not BCC risk. Conclusions Results from the current study suggest that sunlight exposure is associated with both BCC and SCC risk regardless of the pattern in which the exposure was received (i.e. intermittent vs. continuous). The data also suggest that sunlight exposure at a younger age may be more important for SCC but not BCC, however additional studies are needed to further characterize sunlight exposure-response relationships in different types of NMSC. PMID:22994655

2012-01-01

195

The varying impact of type, timing and frequency of exposure to childhood adversity on its association with adult psychotic disorder  

PubMed Central

Background Childhood adversity has been associated with onset of psychosis in adulthood but these studies have used only general definitions of this environmental risk indicator. Therefore, we sought to explore the prevalence of more specific adverse childhood experiences amongst those with and without psychotic disorders using detailed assessments in a large epidemiological case-control sample (ÆSOP). Method Data were collected on 182 first-presentation psychosis cases and 246 geographically-matched controls in two UK centres. Information relating to the timing and frequency of exposure to different types of childhood adversity (neglect, antipathy, physical and sexual abuse, local authority care, disrupted living arrangements and lack of supportive figure) was obtained using the Childhood Experience of Care and Abuse Questionnaire. Results Psychosis cases were three times more likely to report severe physical abuse from mother that commenced prior to 12 years of age, even after adjustment for other significant forms of adversity and demographic confounders. A non-significant trend was also evident for greater prevalence of reported severe maternal antipathy amongst those with psychosis. Associations with maternal neglect and childhood sexual abuse disappeared after adjusting for maternal physical abuse and antipathy. Paternal maltreatment and other forms of adversity were not associated with psychosis nor was there evidence of a dose-response effect. Conclusions These findings suggest that only specific adverse childhood experiences are associated with psychotic disorders and only in a minority of cases. If replicated, this greater precision will ensure that research into the mechanisms underlying the pathway from childhood adversity to psychosis is more fruitful. PMID:20178679

Fisher, Helen L.; Jones, Peter B.; Fearon, Paul; Craig, Thomas K.; Dazzan, Paola; Morgan, Kevin; Hutchinson, Gerard; Doody, Gillian A.; McGuffin, Peter; Leff, Julian; Murray, Robin M.; Morgan, Craig

2012-01-01

196

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)

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.

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

2014-12-01

197

GPS-based microenvironment tracker (MicroTrac) model to estimate time-location of individuals for air pollution exposure assessments: model evaluation in central North Carolina.  

PubMed

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 to do so can add uncertainty and bias to risk estimates. In this study, a classification model, called MicroTrac, was developed to estimate time of day and duration spent in eight ME (indoors and outdoors at home, work, school; inside vehicles; other locations) from global positioning system (GPS) data and geocoded building boundaries. Based on a panel study, MicroTrac estimates were compared with 24-h diary data from nine participants, with corresponding GPS data and building boundaries of home, school, and work. MicroTrac correctly classified the ME for 99.5% of the daily time spent by the participants. The capability of MicroTrac could help to reduce the time-location uncertainty in air pollution exposure models and exposure metrics for individuals in health studies. PMID:24619294

Breen, Michael S; Long, Thomas C; Schultz, Bradley D; Crooks, James; Breen, Miyuki; Langstaff, John E; Isaacs, Kristin K; Tan, Yu-Mei; Williams, Ronald W; Cao, Ye; Geller, Andrew M; Devlin, Robert B; Batterman, Stuart A; Buckley, Timothy J

2014-07-01

198

Antimycobacterial agents differ with respect to their bacteriostatic versus bactericidal activities in relation to time of exposure, mycobacterial growth phase, and their use in combination  

Microsoft Academic Search

A number of antimycobacterial agents were evaluated with respect to their bacteriostatic activity (growth inhibition) versus the bactericidal activity against a clinical isolate of Mycobacterium avium (Mycobacterium avium complex [MAC] strain 101) in relation to the time of exposure and the growth phase of the mycobacteria. In terms of growth inhibition the MAC in the active phase of growth was

Irma A. J. M. Bakker-Woudenberg; Wim van Vianen; Dick van Soolingen; Henri A. Verbrugh; Agtmael van M. A

2005-01-01

199

Effects of exposure time on variations in the structure and hydrophobicity of polyvinylidene fluoride membranes prepared via vapor-induced phase separation  

NASA Astrophysics Data System (ADS)

The present investigation revealed how the surface morphology and hydrophobicity of polyvinylidene fluoride (PVDF) membranes, which were prepared via a vapor-induced phase separation (VIPS) method, were affected by the exposure time. The mass variation of the cast film was recorded. Membrane morphologies were observed by scanning electron microscopy (SEM) and thermal behaviors of membranes were examined by differential scanning calorimetry (DSC). Wide angle X-ray diffraction (WAXD) was employed to analyze the crystalline structures of the overall membranes and the surface layers. The results showed that different membrane morphologies and hydrophobicities could be obtained by changing the exposure time. A long exposure time facilitated the crystallization process, resulting in the formation of a porous skin and particle morphology, which increased the hydrophobicity of the surface. A short exposure time favored the formation of a digitate macrovoid and dense skin resulting from liquid-liquid phase separation in the immersion process, which reduced surface hydrophobicity. The water permeate flux in vacuum membrane distillation was greatly affected by the membrane porosity and surface hydrophobicity.

Peng, Yuelian; Fan, Hongwei; Dong, Yajun; Song, Yanna; Han, Hua

2012-08-01

200

INDOOR/OUTDOOR AEROSOL CONCENTRATION RATIOS DURING THE 1999 FRESNO PARTICULATE MATTER EXPOSURE STUDIES AS A FUNCTION OF SIZE, SEASON, AND TIME OF DAY  

EPA Science Inventory

The 1999 Fresno particulate matter exposure studies tools place in February (winter season) and April/May (spring season) for two periods of four weeks. During that time, near-continuous measurements of indoor and outdoor aerosol concentrations were made with a scanning mobilit...

201

Development of the murine and human immune system: differential effects of immunotoxicants depend on time of exposure.  

PubMed Central

Fetal and early postnatal life represent critical periods in vertebrate immune system development. Disruption of such development by perinatal immunotoxic chemical exposure has been widely described in experimental animal models. The resultant inhibited postnatal immune responses in such animals are often more dramatic and persistent than those after exposure during adult life. Further, recent reports suggest that prenatal exposure to immunotoxicants may exacerbate postnatal aberrant immune responses (e.g., hypersensitivity disorders and autoimmune disease) in genetically predisposed rodents. Limited information is available regarding the possibility of inhibited postnatal immune capacity in humans as a result of developmental immunotoxicant exposure. The multifactorial nature of hypersensitivity and autoimmune responses will further complicate the elucidation of possible relationships between chemical exposure during ontogeny of the human immune system and immune-mediated disease later in life. Taken together, however, the available animal data suggest the potential for altered postnatal immune function in humans exposed to immunotoxicants (e.g., environmental chemicals and therapeutic agents) during fetal and/or early postnatal life. PMID:10852846

Holladay, S D; Smialowicz, R J

2000-01-01

202

DEFICITS IN TRACE FEAR CONDITIONING IN A RAT MODEL OF FETAL ALCOHOL EXPOSURE: DOSE-RESPONSE AND TIMING EFFECTS  

PubMed Central

In humans, prenatal alcohol exposure can result in significant impairments in several types of learning and memory, including declarative and spatial memory. Animal models have been useful for confirming that many of the observed effects are the result of alcohol exposure, and not secondary to poor maternal nutrition or adverse home environments. Wagner and Hunt (2006) reported that rats exposed to ethanol during the neonatal period (postnatal days [PD] 4–9) exhibited impaired trace fear conditioning when trained as adolescents, but were unaffected in delay fear conditioning. The present series of three experiments represent a more detailed analysis of ethanol-induced deficits in trace conditioning. In Experiment 1 the dose of ethanol given to neonates was varied (3.0, 4.0 or 5.0 g/kg/day). There was a dose-dependent reduction in trace conditioning, with the poorest performance observed in animals treated with the highest dose. In Experiment 2 it was found that the impairment in trace conditioning resulting from neonatal ethanol exposure was dependent on the duration of the trace interval used for training; less learning was evident in ethanol-exposed animals trained with longer trace interval durations. These results confirm other reports of delay-dependent memory deficits. Finally, Experiment 3 determined that ethanol exposure limited to the first half of the neonatal period (PD 4–6) was more detrimental to later trace conditioning than exposure during the second half (PD 7–9). These results support the hypothesis that trace conditioning impairments resulting from early ethanol exposure are due to the drug’s teratogenic effects on the developing hippocampus, as the findings parallel those observed in animals with discrete hippocampal lesions. Comparisons between delay and trace fear conditioning performance in animals exposed to ethanol during the brain growth spurt provide a model system to study both selective learning impairments and possible treatment approaches for humans with fetal alcohol spectrum disorders. PMID:19801276

Hunt, Pamela S.; Jacobson, Sarah E.; Torok, Elena J.

2009-01-01

203

Insights of Unconventionally Long Exposure Time in Atomic Layer Deposition Al2O3 to Modify SnO2 Photoanode of Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Porous SnO2 photoanodes coated by alumina through atomic layer deposition technology are reported. It is found that when the dosing time of precursor is extended over 11 s, the 125% maximum increase of cell efficiency is achieved. It is believed that besides the interfacial charge recombination being efficiently suppressed by this ultra-thin coating, the increased absorption of dyes and elimination of the high density of monoenergetic surface states on SnO2 might play a positive role in improving the cell efficiency. The reason is that a long exposure time of precursor can guarantee the 100% coverage of alumina on porous SnO2, which is further explained by a built three-step model. Then we conclude that for a high cell efficiency in porous photoelectrode a long exposure time is indispensable.

Dong, Wan; Wang, Zheng-Duo; Yang, Li-Zhen; Meng, Tao; Chen, Qiang

2014-09-01

204

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

PubMed Central

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 mm2, 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. PMID:23635281

Burion, Steve; Speidel, Michael A.; Funk, Tobias

2013-01-01

205

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

SciTech Connect

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.

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

206

Matching methods to create paired survival data based on an exposure occurring over time: a simulation study with application to breast cancer  

PubMed Central

Background Paired survival data are often used in clinical research to assess the prognostic effect of an exposure. Matching generates correlated censored data expecting that the paired subjects just differ from the exposure. Creating pairs when the exposure is an event occurring over time could be tricky. We applied a commonly used method, Method 1, which creates pairs a posteriori and propose an alternative method, Method 2, which creates pairs in “real-time”. We used two semi-parametric models devoted to correlated censored data to estimate the average effect of the exposure HR¯(t): the Holt and Prentice (HP), and the Lee Wei and Amato (LWA) models. Contrary to the HP, the LWA allowed adjustment for the matching covariates (LWA a ) and for an interaction (LWA i ) between exposure and covariates (assimilated to prognostic profiles). The aim of our study was to compare the performances of each model according to the two matching methods. Methods Extensive simulations were conducted. We simulated cohort data sets on which we applied the two matching methods, the HP and the LWA. We used our conclusions to assess the prognostic effect of subsequent pregnancy after treatment for breast cancer in a female cohort treated and followed up in eight french hospitals. Results In terms of bias and RMSE, Method 2 performed better than Method 1 in designing the pairs, and LWA a was the best model for all the situations except when there was an interaction between exposure and covariates, for which LWA i was more appropriate. On our real data set, we found opposite effects of pregnancy according to the six prognostic profiles, but none were statistically significant. We probably lacked statistical power or reached the limits of our approach. The pairs’ censoring options chosen for combination Method 2 - LWA had to be compared with others. Conclusions Correlated censored data designing by Method 2 seemed to be the most pertinent method to create pairs, when the criterion, which characterized the pair, was an exposure occurring over time. In such a setting, the LWA was the most appropriate model. PMID:24965571

2014-01-01

207

Objectives Class Time Grade Level Subjects Addressed Getting a Handle on Biosolids: New Model Estimates Microbial Exposure Risk  

E-print Network

Students read an article about a model developed to estimate the risk of exposure to pathogenic microbes when treated sewage waste (biosolids) is applied to fields. Next, they conduct an experiment to identify how soil/substrate material can affect water flow and design a simple model to show how different soils/substrate materials might affect bacteria survival. Students think critically to identify additional variables considered in the model. Experiment—students collect, manipulate, and/or summarize data from an experiment or activity they conduct. Thematic—this lesson can be used alone or as part of a series of lessons to develop deeper understanding of a topic or concept. Thematic Lesson 2 for September 2008, “Will I Get Sick? Modeling Microbe Exposure with Math, ” can be implemented after this lesson to develop greater understanding of modeling, the use of mathematics in modeling, and assumptions made in modeling.

Environ Health Perspect; a

2008-01-01

208

Time course of congener uptake and elimination in rats after short-term inhalation exposure to an airborne polychlorinated biphenyl (PCB) mixture.  

PubMed

Despite the continued presence of PCBs in indoor and ambient air, few studies have investigated the inhalation route of exposure. While dietary exposure has declined, inhalation of the semivolatile, lower-chlorinated PCBs has risen in importance. We measured the uptake, distribution, and time course of elimination of inhaled PCB congeners to characterize the pulmonary route after short-term exposure. Vapor-phase PCBs were generated from Aroclor 1242 to a nose-only exposure system and characterized for congener levels and profiles. Rats were exposed via inhalation acutely (2.4 mg/m3 for 2 h) or subacutely (8.2 mg/m3, 2 hx10 days), after which pulmonary immune responses and PCB tissue levels were measured. Animals acutely exposed were euthanized at 0, 1, 3, 6, and 12 h post exposure to assess the time course of PCB uptake and elimination. Following rapid absorption and distribution, PCBs accumulated in adipose tissue but decayed in other tissues with half-lives increasing in liver (5.6 h)

Hu, Xin; Adamcakova-Dodd, Andrea; Lehmler, Hans-Joachim; Hu, Dingfei; Kania-Korwel, Izabela; Hornbuckle, Keri C; Thorne, Peter S

2010-09-01

209

Time- and concentration-dependent metabolic and genomic responses to exposure to resin acids in brown trout (Salmo trutta m. lacustris).  

PubMed

The presence of metabolically conjugated resin acids (RAs) in the bile is considered to be a sensitive indicator for exposure of fish to pulp and paper industry effluents; however, to our knowledge, no comprehensive kinetic study of this response has been made. Juvenile brown trout (Salmo trutta m. lacustris) were exposed to a waterborne mixture of seven RAs (wood rosin) in time (0.1-192.0 h; average concentration, 8 microg/L) and dose (average concentrations, 0, 0.6, 4, 14, and 78 microg/L; 10 d) series, and total RAs were analyzed in bile. In time-dependent exposure, total RAs in bile increased up to 24 h. In concentration-dependent exposure, RAs increased along with the concentration of RAs in water, revealing a high-capacity biotransformation and elimination system in trout liver. In concentration-dependent exposures, the effects on the hepatic transcriptome was studied using a high-density cDNA microarray, and dose-dependent changes were found in a large number of genes. Resin acids interfered with iron metabolism, as evidenced by the decrease in transcripts for iron transporters and heme-containing proteins. Expression of genes encoding for enzymes degrading reactive oxygen species also decreased. Coordinated down-regulation of the protein biosynthesis machinery could result from inhibition of the energy metabolism. A number of changes in gene expression indicated recovery and remodeling of hepatic tissues. We conclude that analysis of total RAs in the bile provides a sensitive and quantitative tool for assessing the exposure of fish to waterborne RAs, whereas multiple gene expression analyses are able to elucidate simultaneous cellular functions for use as potential biomarkers of RAs. PMID:17702544

Meriläinen, Päivi S; Krasnov, Aleksei; Oikari, Aimo

2007-09-01

210

Contact toxicity of permethrin-impregnated fabric to Hyalomma anatolicum excavatum (Acari: Ixodidae): effects of laundering and exposure and recovery times.  

PubMed

A previous study that documented enhanced host attachment by the camel ticks Hyalomma dromedarii Koch after permethrin exposure prompted a similar investigation of permethrin effects in H. anatolicum excavatum Koch, an Old World hardbacked tick suspected of vectoring human pathogens. Contact toxicity tests were conducted with laboratory-colonized male and female H. a. excavatum of the same age exposed for periods of 5, 10, 30, and 60 min to each of 5 fabric treatments: unwashed/untreated; unwashed and treated; and treated fabric given 1, 2, or 3 laundry cycles of warm-water detergent machine washing, followed by hot-air drying. Fabric was tropical weight 100% cotton military uniform. Treated fabric was impregnated with permethrin at 0.125 mg (AI)/cm2. Contact toxicity was measured immediately after and 24 h after fabric contact as proportion of ticks that attached mouthparts to the skin of a host (rabbit) within a 60-min quest period and time lapse (minutes) between contact with the host and attachment. Attachment response immediately after permethrin contact was exposure time- and wash-dependent in both sexes. Proportion of attaching ticks and times to attachment were comparable in controls and in groups exposed to all permethrin-treated fabrics for 5 or 10 min. Contact periods of 30 and 60 min with 0-wash/treated or 1-wash and treated fabric significantly reduced the frequency of attachment and significantly prolonged mean times to attachment. Compared with low levels of attachment response observed immediately after fabric contact, recovery of attachment response was observed 24 h after exposure in these wash/treatment groups, but inhibition was still evident. Permethrin-induced intoxication was more pronounced in males than females. Mortality 24 h after exposure was only significant among females exposed to 0-wash/treated fabric for 60 min. There was no evidence of permethrin-mediated stimulation of the attachment response in H. a. excavatum. PMID:9615556

Fryauff, D J; Shoukry, M A; Wassef, H Y; Gray, G; Schreck, C E

1998-05-01

211

Intervening Processes Between Youths’ Exposure to Community Violence and Internalizing Symptoms Over Time: The Roles of Social Support and Coping  

Microsoft Academic Search

The roles of social support and coping as intervening processes between exposure to community violence and internalizing symptoms\\u000a were examined longitudinally among a community sample of 667 middle school students in the inner city. After controlling for\\u000a potential confounders (e.g., social desirability, victimization and witnessing of family violence, guardian’s psychological\\u000a symptomatology), internalizing symptoms at Year 2 were predicted by hypothesized

Margaret Rosario; Suzanne Salzinger; Richard S. Feldman; Daisy S. Ng-Mak

2008-01-01

212

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

SciTech Connect

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.

Gluth, G.; Hanke, W.

1985-04-01

213

Subsidized childcare and child development in Colombia: effects of Hogares Comunitarios de Bienestar as a function of timing and length of exposure.  

PubMed

Rigorous evidence regarding the impact of early care and education on children's development comes primarily from high-income nations. A few studies from Latin America and the Caribbean have identified benefits of conditional cash transfer and home visiting programs on children's development. However, there is still controversy around the impact and cost-effectiveness of childcare approaches. Further research is needed to understand how scaled-up childcare settings may support the development of low-income children in Latin America. To that end, the present study sought to identify the effects of exposure to a subsidized childcare program in Colombia on children's nutritional status, cognitive and socioemotional development. This community-based program, known as Hogares Comunitarios de Bienestar (HCB), serves 800 thousand low-income children under age 6, delivering home-based childcare, supplementary nutrition, and psychosocial stimulation. We analyzed data on 10,173 program beneficiary children (ages 3-6) collected in 2007. We compared beneficiary children who had been in the program for a long time with beneficiary children who had been in the program for a month or less, by age group, to estimate program exposure effects. We used a matching estimator to correct for self-selection into different exposure levels. Results indicated that cognitive development improved 0.15 to 0.3 of a standard deviation (SD) after at least 15 months of exposure for children between 3 and 6 years of age. Socioemotional skills improved 0.12 to 0.3 SD for children older than 3 after at least 15 months of program exposure. No significant gains were found for nutritional status. The estimated benefit-cost ratio ranged from 1.0 to 2.7, depending upon varying discount rates. Findings lend support for a potentially effective strategy to promote the development of low-income children in Colombia and other developing nations. PMID:23312302

Bernal, Raquel; Fernández, Camila

2013-11-01

214

Effects of long-time elevated temperature exposures on hot-isostatically-pressed power-metallurgy Udimet 700 alloys with reduced cobalt contents  

NASA Technical Reports Server (NTRS)

Because almost the entire U.S. consumption of cobalt depends on imports, this metal has been designated "strategic'. The role and effectiveness of cobalt is being evaluated in commercial nickel-base superalloys. Udiment 700 type alloys in which the cobalt content was reduced from the normal 17% down to 12.7%, 8.5%, 4.3%, and 0% were prepared by standard powder metallurgy techniques and hot isostatically pressed into billets. Mechanical testing and microstructural investigations were performed. The mechanical properties of alloys with reduced cobalt contents which were heat-treated identically were equal or better than those of the standard alloy, except that creep rates tended to increase as cobalt was reduced. The effects of long time exposures at 760 C on mechanical properties and at 760 C and 845 C on microstructures were determined. Decreased tensile properties and shorter rupture lives with increased creep rates were observed in alloy modifications. The exposures caused gamma prime particle coarsening and formation of sigma phase in the alloys with higher cobalt contents. Exposure at 845 C also reduced the amount of MC carbides.

Hart, F. H.

1984-01-01

215

Paired 26Al and 10Be exposure ages from Lundy: new evidence for the extent and timing of Devensian glaciation in the southern British Isles  

NASA Astrophysics Data System (ADS)

Lundy lies in a strategic geographical position for understanding the glacial history of the British Isles. The island bears evidence of glaciation, largely in the form of ice-moulded bedrock and glacially-transported boulders - an unusual occurrence this far south in the British Isles. Irish Sea ice penetrated the western Bristol Channel overriding Lundy from the northwest during the last phase of glaciation in this area. The results of paired terrestrial cosmogenic nuclide analyses (26Al/10Be) constrain the timing of this extensive glaciation and provide, for the first time, an age for the exposure of Lundy granite following deglaciation. The results from nine paired samples yield 26Al/10Be exposure ages of 31.4-48.8 ka (10Be) and 31.7-60.0 ka (26Al). This challenges the view that any glaciation this far south must belong to Middle Pleistocene glaciations, such as the Anglian Stage (c. 480-420 ka) and a Devensian age for the last glaciation is consistent with findings from the Isles of Scilly further south. However, the findings suggest early-mid Devensian (marine isotope stage (MIS) 4-3) glaciation of Lundy. It also implies that the island was exposed or covered for a short time by non-erosive cold-based ice at the global Last Glacial Maximum (LGM) during MIS 2 (26-21 ka). The potential exposure of the island throughout MIS 2 contrasts with the evidence from the Isles of Scilly and the Celtic Sea, which were glaciated at the LGM.

Rolfe, C. J.; Hughes, P. D.; Fenton, C. R.; Schnabel, C.; Xu, S.; Brown, A. G.

2012-06-01

216

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

PubMed

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

Lopes, Aline; Piedade, Maria Teresa Fernandez

2014-12-01

217

Real-time In Situ Electron Spin Resonance Measurements on Fungal Spores of Penicillium digitatum during Exposure of Oxygen Plasmas  

E-print Network

We report the kinetic analysis of free radicals on fungal spores of Penicillium digitatum interacted with atomic oxygen generated plasma electric discharge using real time in situ electron spin resonance (ESR) measurements. We have obtained information that the ESR signal from the spores was observed and preliminarily assignable to semiquinone radical with a g-value of around 2.004 and a line width of approximately 5G. The decay of the signal is possibly linked to the inactivation of the fungal spore. The real-time in situ ESR has proven to be a useful method to elucidate plasma-induced surface reactions on biological specimens.

Ishikawa, Kenji; Tanaka, Hiromasa; Tamiya, Kazuhiro; Hashizume, Hiroshi; Ohta, Takayuki; Ito, Masafumi; Iseki, Sachiko; Takeda, Keigo; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

2012-01-01

218

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

PubMed

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

Ha, Mi-Hee; Pflugmacher, Stephan

2013-08-15

219

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

PubMed

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

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; Seneda, Marcelo M

2014-09-01

220

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

PubMed Central

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

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

221

Variation in body composition in professional soccer players: interseasonal and intraseasonal changes and the effects of exposure time and player position.  

PubMed

The aim of this study was to examine variations in measures of body composition in elite soccer players. Skinfolds and measures of body mass (BM) recorded on a monthly basis across an entire competitive season in a group of senior professional players (n = 26) were used to estimate percentage body fat (%BF) and provide fat-free body mass (FFBM) values. Mean values in players were compared between 6 specific positional roles (goalkeepers, central and lateral defenders/midfielders and center-forwards). In-season variations in measures were studied by comparing values at 5 separate points across the season. The effects of positional group (goalkeepers, defenders, midfielders, and forwards) and exposure time to play (participation time in training and matches) in relation to in-season variations were also examined. To investigate interseasonal changes, repeated measures were taken in players (n = 9) over 3 consecutive seasons. In relation to positional role, a difference in average %BF and BM values was observed (p < 0.001), with substantial differences observed in goalkeepers, lateral midfielders, and forwards. Across all players, there were significant in-season variations in %BF (between start- and mid-season and mid- and end-season, p < 0.001) and FFBM (between start- and mid-season and start- and end-season, p < 0.001), whereas BM remained unchanged. Further analysis of these fluctuations in %BF and FFBM at different points of the season showed that variations differed across the positional groups (p < 0.01), especially in defenders and midfielders. In contrast, no association was observed between measures and exposure time and no differences were reported across seasons. Practitioners should consider individual positional role when interpreting mean body composition data. They should also take into account positional groups when in-season variations in body composition are identified. PMID:20393356

Carling, Christopher; Orhant, Emmanuel

2010-05-01

222

The exposure assessment in current time study: implementation, feasibility, and acceptability of real-time data collection in a community cohort of illicit drug users.  

PubMed

Objective. We describe the study design and evaluate the implementation, feasibility, and acceptability of an ecological momentary assessment (EMA) study of illicit drug users. Design. Four sequential field trials targeting observation of 30 individuals followed for a four week period. Participants. Participants were recruited from an ongoing community-cohort of current or former injection drug users. Of 113 individuals enrolled, 109 completed study procedures during four trials conducted from November 2008 to May 2013. Methods. Hand-held electronic diaries used in the initial trials were transitioned to a smartphone platform for the final trial with identical data collection. Random-prompts delivered five times daily assessed participant location, activity, mood, and social context. Event-contingent data collection involved participant self-reports of illicit drug use and craving. Main Outcome Measures. Feasibility measures included participant retention, days of followup, random-prompt response rates, and device loss rate. Acceptability was evaluated from an end-of-trial questionnaire. Sociodemographic, behavioral, clinical, and trial characteristics were evaluated as correlates of weekly random-prompt response rates ?80% using logistic regression with generalized estimating equations. Results. Study participants were a median of 48.5 years old, 90% African American, 52% male, and 59% HIV-infected with limited income and educational attainment. During a median followup of 28 days, 78% of 11,181 random-prompts delivered were answered (mean of 2.8 responses daily), while 2,798 participant-initiated events were reported (30% drug use events; 70% craving events). Self-reported acceptability to study procedures was uniformly favorable. Device loss was rare (only 1 lost device every 190 person-days of observation). Higher educational attainment was consistently associated with a higher response rate to random-prompts, while an association of HIV infection with lower response rates was not observed after accounting for differences in trial recruitment procedures. Conclusion. Near real-time EMA data collection in the field is feasible and acceptable among community-dwelling illicit drug users. These data provide the basis for future studies of EMA-informed interventions to prevent drug relapse and improve HIV treatment outcomes in this population. PMID:24307943

Kirk, Gregory D; Linas, Beth S; Westergaard, Ryan P; Piggott, Damani; Bollinger, Robert C; Chang, Larry W; Genz, Andrew

2013-01-01

223

The Exposure Assessment in Current Time Study: Implementation, Feasibility, and Acceptability of Real-Time Data Collection in a Community Cohort of Illicit Drug Users  

PubMed Central

Objective. We describe the study design and evaluate the implementation, feasibility, and acceptability of an ecological momentary assessment (EMA) study of illicit drug users. Design. Four sequential field trials targeting observation of 30 individuals followed for a four week period. Participants. Participants were recruited from an ongoing community-cohort of current or former injection drug users. Of 113 individuals enrolled, 109 completed study procedures during four trials conducted from November 2008 to May 2013. Methods. Hand-held electronic diaries used in the initial trials were transitioned to a smartphone platform for the final trial with identical data collection. Random-prompts delivered five times daily assessed participant location, activity, mood, and social context. Event-contingent data collection involved participant self-reports of illicit drug use and craving. Main Outcome Measures. Feasibility measures included participant retention, days of followup, random-prompt response rates, and device loss rate. Acceptability was evaluated from an end-of-trial questionnaire. Sociodemographic, behavioral, clinical, and trial characteristics were evaluated as correlates of weekly random-prompt response rates ?80% using logistic regression with generalized estimating equations. Results. Study participants were a median of 48.5 years old, 90% African American, 52% male, and 59% HIV-infected with limited income and educational attainment. During a median followup of 28 days, 78% of 11,181 random-prompts delivered were answered (mean of 2.8 responses daily), while 2,798 participant-initiated events were reported (30% drug use events; 70% craving events). Self-reported acceptability to study procedures was uniformly favorable. Device loss was rare (only 1 lost device every 190 person-days of observation). Higher educational attainment was consistently associated with a higher response rate to random-prompts, while an association of HIV infection with lower response rates was not observed after accounting for differences in trial recruitment procedures. Conclusion. Near real-time EMA data collection in the field is feasible and acceptable among community-dwelling illicit drug users. These data provide the basis for future studies of EMA-informed interventions to prevent drug relapse and improve HIV treatment outcomes in this population. PMID:24307943

Kirk, Gregory D.; Linas, Beth S.; Westergaard, Ryan P.; Piggott, Damani; Bollinger, Robert C.; Chang, Larry W.

2013-01-01

224

Identification of genes differentially expressed in clams Ruditapes philippinarum in response to endosulfan after different exposure time.  

PubMed

This study reports molecular biomarkers potentially associated with resistance or sensitivity to the impact of endosulfan in clams, Ruditapes philippinarum. Genomic analysis was made applying suppression subtractive hybridization (SSH) to identify genes up- and down-regulated in calms exposed to 0.5 ?g/L endosulfan for 1d and 10d. Results obtained from the SSH library revealed 360 different sequences regulated by endosulfan, which correspond to nine major physiological functions. To validate the expression profiles from SSH, 13 genes regulated by endosulfan were measured by quantitative real-time PCR. This study provides information for the characterization of potential molecular biomarker that may be used in future environmental monitoring and to investigate the mechanisms of stress to endosulfan in clams/marine invertebrates. PMID:23290617

Tao, Yanxia; Pan, Luqing; Zhang, Hui; Liu, Na

2013-03-01

225

Combination of a higher-tier flow-through system and population modeling to assess the effects of time-variable exposure of isoproturon on the green algae Desmodesmus subspicatus and Pseudokirchneriella subcapitata.  

PubMed

A flow-through system was developed to investigate the effects of time-variable exposure of pesticides on algae. A recently developed algae population model was used for simulations supported and verified by laboratory experiments. Flow-through studies with Desmodesmus subspicatus and Pseudokirchneriella subcapitata under time-variable exposure to isoproturon were performed, in which the exposure patterns were based on the results of FOrum for Co-ordination of pesticide fate models and their USe (FOCUS) model calculations for typical exposure situations via runoff or drain flow. Different types of pulsed exposure events were realized, including a whole range of repeated pulsed and steep peaks as well as periods of constant exposure. Both species recovered quickly in terms of growth from short-term exposure and according to substance dissipation from the system. Even at a peak 10 times the maximum predicted environmental concentration of isoproturon, only transient effects occurred on algae populations. No modified sensitivity or reduced growth was observed after repeated exposure. Model predictions of algal growth in the flow-through tests agreed well with the experimental data. The experimental boundary conditions and the physiological properties of the algae were used as the only model input. No calibration or parameter fitting was necessary. The combination of the flow-through experiments with the algae population model was revealed to be a powerful tool for the assessment of pulsed exposure on algae. It allowed investigating the growth reduction and recovery potential of algae after complex exposure, which is not possible with standard laboratory experiments alone. The results of the combined approach confirm the beneficial use of population models as supporting tools in higher-tier risk assessments of pesticides. PMID:22328269

Weber, Denis; Schaefer, Dieter; Dorgerloh, Michael; Bruns, Eric; Goerlitz, Gerhard; Hammel, Klaus; Preuss, Thomas G; Ratte, Hans Toni

2012-04-01

226

The hypoxic ventilatory response and ventilatory long-term facilitation are altered by time of day and repeated daily exposure to intermittent hypoxia  

PubMed Central

This study examined whether time of day and repeated exposure to intermittent hypoxia have an impact on the hypoxic ventilatory response (HVR) and ventilatory long-term facilitation (vLTF). Thirteen participants with sleep apnea were exposed to twelve 4-min episodes of isocapnic hypoxia followed by a 30-min recovery period each day for 10 days. On days 1 (initial day) and 10 (final day) participants completed the protocol in the evening (PM); on the remaining days the protocol was completed in the morning (AM). The HVR was increased in the morning compared with evening on the initial (AM 0.83 ± 0.08 vs. PM 0.64 ± 0.11 l·min?1·%SaO2?1; P ? 0.01) and final days (AM 1.0 ± 0.08 vs. PM 0.81 ± 0.09 l·min?1·%SaO2?1; P ? 0.01, where %SaO2 refers to percent arterial oxygen saturation). Moreover, the magnitude of the HVR was enhanced following daily exposure to intermittent hypoxia in the morning (initial day 0.83 ± 0.08 vs. final day 1.0 ± 0.08 l·min?1·%SaO2?1; P ? 0.03) and evening (initial day 0.64 ± 0.11 vs. final day 0.81 ± 0.09 l·min?1·%SaO2?1; P ? 0.03). vLTF was reduced in the morning compared with the evening on the initial (AM 19.03 ± 0.35 vs. PM 22.30 ± 0.49 l/min; P ? 0.001) and final (AM 20.54 ± 0.32 vs. PM 23.11 ± 0.54 l/min; P ? 0.01) days. Following daily exposure to intermittent hypoxia, vLTF was enhanced in the morning (initial day 19.03 ± 0.35 vs. final day 20.54 ± 0.32 l/min; P ? 0.01). We conclude that the HVR is increased while vLTF is decreased in the morning compared with the evening in individuals with sleep apnea and that the magnitudes of these phenomena are enhanced following daily exposure to intermittent hypoxia. PMID:20724571

Gerst, David G.; Yokhana, Sanar S.; Carney, Laura M.; Lee, Dorothy S.; Badr, M. Safwan; Qureshi, Tabarak; Anthouard, Magalie N.

2011-01-01

227

Microbial activity and community diversity in a variable charge soil as affected by cadmium exposure levels and time.  

PubMed

Effects of cadmium (Cd) on microbial biomass, activity and community diversity were assessed in a representative variable charge soil (Typic Aquult) using an incubation study. Cadmium was added as Cd(NO3)(2) to reach a concentration range of 0-16 mg Cd/kg soil. Soil extractable Cd generally increased with Cd loading rate, but decreased with incubation time. Soil microbial biomass was enhanced at low Cd levels (0.5-1 mg/kg), but was inhibited consistently with increasing Cd rate. The ratio of microbial biomass C/N varied with Cd treatment levels, decreasing at low Cd rate (<0.7 mg/kg available Cd), but increasing progressively with Cd loading. Soil respiration was restrained at low Cd loading (<1 mg/kg), and enhanced at higher Cd levels. Soil microbial metabolic quotient (MMQ) was generally greater at high Cd loading (1-16 mg/kg). However, the MMQ is also affected by other factors. Cd contamination reduces species diversity of soil microbial communities and their ability to metabolize different C substrates. Soils with higher levels of Cd contamination showed decreases in indicator phospholipids fatty acids (PLFAs) for Gram-negative bacteria and actinomycetes, while the indicator PLFAs for Gram-positive bacteria and fungi increased with increasing levels of Cd contamination. PMID:18357628

Shentu, Jia-li; He, Zhen-li; Yang, Xiao-e; Li, Ting-qiang

2008-03-01

228

Microbial activity and community diversity in a variable charge soil as affected by cadmium exposure levels and time*  

PubMed Central

Effects of cadmium (Cd) on microbial biomass, activity and community diversity were assessed in a representative variable charge soil (Typic Aquult) using an incubation study. Cadmium was added as Cd(NO3)2 to reach a concentration range of 0~16 mg Cd/kg soil. Soil extractable Cd generally increased with Cd loading rate, but decreased with incubation time. Soil microbial biomass was enhanced at low Cd levels (0.5~1 mg/kg), but was inhibited consistently with increasing Cd rate. The ratio of microbial biomass C/N varied with Cd treatment levels, decreasing at low Cd rate (<0.7 mg/kg available Cd), but increasing progressively with Cd loading. Soil respiration was restrained at low Cd loading (<1 mg/kg), and enhanced at higher Cd levels. Soil microbial metabolic quotient (MMQ) was generally greater at high Cd loading (1~16 mg/kg). However, the MMQ is also affected by other factors. Cd contamination reduces species diversity of soil microbial communities and their ability to metabolize different C substrates. Soils with higher levels of Cd contamination showed decreases in indicator phospholipids fatty acids (PLFAs) for Gram-negative bacteria and actinomycetes, while the indicator PLFAs for Gram-positive bacteria and fungi increased with increasing levels of Cd contamination. PMID:18357628

Shentu, Jia-li; He, Zhen-li; Yang, Xiao-e; Li, Ting-qiang

2008-01-01

229

Virtual reality exposure therapy.  

PubMed

It has been proposed that virtual reality (VR) exposure may be an alternative to standard in vivo exposure. Virtual reality integrates real-time computer graphics, body tracking devices, visual displays, and other sensory input devices to immerse a participant in a computer-generated virtual environment. Virtual reality exposure is potentially an efficient and cost-effective treatment of anxiety disorders. VR exposure therapy reduced the fear of heights in the first controlled study of virtual reality in treatment of a psychiatric disorder. A case study supported the efficacy of VR exposure therapy for the fear of flying. The potential for virtual reality exposure treatment for these and other disorders is explored, and therapeutic issues surrounding the delivery of VR exposure are discussed. PMID:9185067

Rothbaum, B O; Hodges, L; Kooper, R

1997-01-01

230

Time-response relationships for the accumulation of Cu, Ni and Zn by seven-spotted ladybirds (Coccinella septempunctata L.) under conditions of single and combined metal exposure.  

PubMed

Accumulation, and therefore toxicity, of trace metals in invertebrates may be affected by potential interactive effects that can occur amongst different metallic elements. However, there is little data on the nature and effects of such interactions in terrestrial systems. This work reports the interactions among Cu, Ni and Zn during accumulation by the beetle Coccinella septempunctata. Test animals were treated with 500mgkg(-1) of each metal singularly and in combination for 15d. The effects of treatment with a single metal had no effect on the baseline concentrations of the other two. Time-response relationships for Cu and Ni after treatment with one metal were curvilinear, demonstrating that the metals were initially accumulated, but after ?8d regulatory mechanisms became effective. This resulted in decreasing concentrations in test animals despite continued treatment. In contrast, the time-response relationship for Zn was linear. Treatment with metals in combination markedly altered the time-response relationships with all three metals showing a linear trend and the slope of the Zn relationship increasing significantly. After 15d of exposure this had the effect of increasing the metal concentration in animals exposed in combination compared to those exposed singularly by 144% to 38.3mgkg(-1) for Cu, 141% to 27.5mgkg(-1) for Ni and 55% to 311mgkg(-1) for Zn. For all metals, differences amongst treatments were significant, indicating that inter-element interactions can enhance the concentration of trace metals in C. septempunctata. PMID:23810517

Green, I D; Walmsley, K

2013-09-01

231

Real-time and time-integrated PM2.5 and CO from prescribed burns in chipped and non-chipped plots: firefighter and community exposure and health implications.  

PubMed

In this study, smoke data were collected from two plots located on the Francis Marion National Forest in South Carolina during prescribed burns on 12 February 2003. One of the plots had been subjected to mechanical chipping, the other was not. This study is part of a larger investigation of fire behavior related to mechanical chipping, parts of which are presented elsewhere. The primary objective of the study reported herein was to measure PM(2.5) and CO exposures from prescribed burn smoke from a mechanically chipped vs. non-chipped site. Ground-level time-integrated PM(2.5) samplers (n=9/plot) were placed at a height of 1.5 m around the sampling plots on the downwind side separated by approximately 20 m. Elevated time-integrated PM(2.5) samplers (n=4/plot) were hung atop approximately 30 ft poles at positions within the interior of each of the plots. Real-time PM(2.5) and CO data were collected at downwind locations on the perimeter of each plot. Time-integrated perimeter 12-h PM(2.5) concentrations in the non-chipped plot (AVG 519.9 microg/m(3), SD 238.8 microg/m(3)) were significantly higher (1-tail P-value 0.01) than those at the chipped plot (AVG 198.1 microg/m(3), SD 71.6 microg/m(3)). Similarly, interior time-integrated 8-h PM(2.5) concentrations in the non-chipped plot (AVG 773.4 microg/m(3), SD 321.8 microg/m(3)) were moderately higher (1-tail P-value 0.06) than those at the chipped plot (AVG 460.3 microg/m(3), SD 147.3 microg/m(3)). Real-time PM(2.5) and CO data measured at a position in the chipped plot were uniformly lower than those observed at the same position in the non-chipped plot over the same time period. These results demonstrate that smoke exposures resulting from burned chipped plots are considerably lower than from burned non-chipped plots. These findings have potentially important implications for both firefighters working prescribed burnings at chipped vs. non-chipped sites, as well as nearby communities who may be impacted from smoke traveling downwind from these sights. PMID:16736059

Naeher, Luke P; Achtemeier, Gary L; Glitzenstein, Jeff S; Streng, Donna R; Macintosh, David

2006-07-01

232

Exposure Corrections for Macrophotography  

ERIC Educational Resources Information Center

Describes a method for determining the exposure correction factors in close-up photography and macrophotography. The method eliminates all calculations during picture-taking, and allows the use of a light meter to obtain the proper f-stop/exposure time combinations. (Author/MLH)

Nikolic, N. M.

1976-01-01

233

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)

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.

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

1974-01-01

234

Time?  

NASA Astrophysics Data System (ADS)

The concept of time in the `clockwork' Newtonian world was irrelevant; and has generally been ignored until recently by several generations of physicists since the implementation of quantum mechanics. We will set aside the utility of time as a property relating to physical calculations of events relating to a metrics line element or as an aspect of the transformation of a particles motion/interaction in a coordinate system or in relation to thermodynamics etc., i.e. we will discard all the usual uses of time as a concept used to circularly define physical parameters in terms of other physical parameters; concentrating instead on time as an aspect of the fundamental cosmic topology of our virtual reality especially as it inseparably relates to the nature and role of the observer in natural science.

Amoroso, Richard L.

2013-09-01

235

Personal radiofrequency electromagnetic field measurements in The Netherlands: exposure level and variability for everyday activities, times of day and types of area.  

PubMed

Knowledge of the exposure to radiofrequency electromagnetic fields is necessary for epidemiological studies on possible health effects. The main goal of this study is to determine the exposure level and spatial and temporal variances during 39 everyday activities in 12 frequency bands used in mobile telecommunication and broadcasting. Therefore, 24 h measurements were gathered from 98 volunteers living in or near Amsterdam and Purmerend, The Netherlands. They carried an activity diary to be kept to the minute, a GPS logger sampling at an interval of 1 s, and an EME Spy exposimeter with a detection limit of 0.0066 mW/m(2) sampling at an interval of 10s in 12 frequency bands. The mean exposure over 24 h, excluding own mobile phone use, was 0.180 mW/m(2). During daytime exposure was about the same, but during night it was about half, and in the evening it was about twice as high. The main contribution to environmental exposure (calling by participant not included) is from calling with mobile phones (37.5%), from cordless DECT phones and their docking stations (31.7%), and from the base stations (12.7%). The exposure to mobile phone base stations increases with the percentage of urban ground use, which is an indication for high people density. In agreement, the highest mean exposure relates to the activities with high people density, such as travelling by public transport, visiting social events, pubs or shopping malls. Exposure at home depends mainly on exposure from people calling in the neighbourhood of the participant and thus on the number of persons in a household. In addition just the possession of DECT docking stations leads to exposure as most models transmit continuously in stand-by. Also wireless internet routers continuously transmit in the WiFi band. Though the highest exposure peaks in the WiFi band, up to 0.265 W/m(2), come from stray radiation of microwave ovens. The mean total exposure largely depends on phone calls of a high exposure level and short duration. These calls lead to potentially high contrasts as well in exposure levels between sessions of the same activity as between persons, thus posing a challenge for personal exposure prediction. PMID:22906414

Bolte, John F B; Eikelboom, Tessa

2012-11-01

236

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

237

Urine pH, container composition, and exposure time influence adsorptive loss of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid.  

PubMed

11-nor-delta9-Tetrahydrocannabinol-9-carboxylic acid (11-nor-delta9-THC-COOH) is the primary cannabinoid present in the urine of individuals who have used marijuana and is the target analyte identified at forensic urinalysis drug testing laboratories. The preparation, storage, transport, and processing of control materials for gas chromatography-mass spectrometric (GC-MS) analysis of human urine specimens is critical to accurate compound identification and quantification. Previous studies have suggested that adsorptive loss of 11-nor-delta9-THC-COOH is influenced by container composition and storage temperature. In this study, urine solutions of 11-nor-delta9-THC-COOH (7.5, 15, 60, and 500 ng/mL) at three physiologically-relevant pHs (4.6, 6.5, and 8.4) were prepared and subjected to storage and processing in containers of different compositions (polypropylene and borosilicate glass). Analyte identification and quantification were achieved using tetramethylammonium hydroxide/iodomethane-based derivatization followed by GC separation and electron-impact MS. These analyses demonstrate that adsorptive loss of 11-nor-delta9-THC-COOH is a phenomenon found in acidic urine solutions and is relatively absent in urine solutions that are near-neutral or basic. Furthermore, the data indicate that the adsorptive loss of 11-nor-delta9-THC-COOH is dependent on solution-container exposure time and is similar between containers of two distinct compositions. These results suggest that for optimal analytical control performance, solution pH and control processing times are critical elements. PMID:16419391

Jamerson, Matthew H; McCue, Joseph J; Klette, Kevin L

2005-10-01

238

DEVELOPMENT OF REAL-TIME SITE-SPECIFIC MICROSCALE EMISSION FACTOR MODEL FOR THE ASSESSMENT OF HUMAN EXPOSURE TO MOTOR VEHICLE EMISSIONS  

EPA Science Inventory

The United States Environmental Protection Agency's (EPA) National Expsoure Research Laboratory (NERL) has initiated a project to improve the methodology for modeling urban-scale human exposure to mobile source emissions. The modeling project has started by considering the nee...

239

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...

240

Development of the county database: Estimates of exposure rates and times of arrival of fallout in the ORERP Phase-2 area. Comparison with cumulative deposition-density estimates based on analyses of retrospective and historical soil samples.  

National Technical Information Service (NTIS)

Estimates of exposure rates and fallout-arrival times have been made for each of 142 counties or county segments for 55 nuclear events producing significant deposition downwind from the Nevada Test Site. All sources of available data were examined to prov...

H. L. Beck, L. R. Anspaugh

1991-01-01

241

Inter-laboratory study of short time exposure (STE) test for predicting eye irritation potential of chemicals and correspondence to globally harmonized system (GHS) classification.  

PubMed

Short time exposure (STE) test using rabbit corneal cell line (SIRC) cells was developed as an alternative eye irritation test. STE test uses relative viability as the endpoint after cells are exposed to the test material at constant concentrations for 5 min. In this inter-laboratory study with 3 laboratories, 44 chemicals with a wide range of classes were evaluated for the transferability, between-lab reproducibility and predictive capacity of the STE test as an alternative eye irritation test. Globally harmonized system (GHS) classification based on Draize eye irritation test data was used as the comparative in vivo data. Transferability was assessed using standard chemicals (sodium lauryl sulfate, calcium thioglycolate, and Tween 80) and the coefficient variations (CVs) of relative viabilities between 3 labs were less than 0.13. The irritation category (Irritant or Non irritant) at each test concentration (5% and 0.05%) in STE test was the same in 3 laboratories for all 44 tested chemicals. The predictive capacity irritation category classification between STE test and GHS were compared, and a good correlation was confirmed (accuracy was 90.9% at all laboratories). In addition, the STE rankings of 1, 2, and 3 classified by the prediction model (PM) based on the relative viability at two concentrations (5% and 0.05%) were highly correlated with the GHS ranks of non-irritant, category 1, and category 2, respectively (accuracy was 75.0% at all laboratories). These results suggest that the STE test possessed easy transferability, reproducibility, good predictive performance. PMID:19952497

Takahashi, Yutaka; Hayashi, Takumi; Watanabe, Shinichi; Hayashi, Kazuhiko; Koike, Mirei; Aisawa, Noriko; Ebata, Shinya; Sakaguchi, Hitoshi; Nakamura, Tsuneaki; Kuwahara, Hirofumi; Nishiyama, Naohiro

2009-12-01

242

Environmental Exposures and Development  

PubMed Central

Structured Abstract Purpose of Review Summarize recent studies exploring the relationship between paternal and maternal environmental exposures to chemicals before, at the time of and after conception to adverse developmental outcomes including; preterm birth, death, structural and functional abnormalities and growth restriction. Recent Findings Recent studies have demonstrated that human pregnancy and development is vulnerable to environmental exposures of the father and mother to chemical, biological and physical agents. Exposures associated with adverse developmental outcomes include; air and water pollution, chemicals in foods, occupational exposures, agricultural chemicals, metals, persistent and volatile organics. Developmental endpoints which are linked with these exposures include; growth restriction, functional abnormalities, structural abnormalities, preterm delivery and death. Despite this general understanding we still have incomplete knowledge concerning most exposures and the biological interactions responsible for impaired development and preterm delivery. Summary While single genes and individual chemical exposures are responsible for some instances of adverse pregnancy outcome or developmental disease, gene-environment interactions are responsible for the majority. These gene-environment interactions may occur in the father, mother, placenta or fetus suggesting that critical attention be given to maternal and paternal exposures and gene expression as they relate to the mode of action of the putative developmental toxicant both prior to and during pregnancy. PMID:20216314

Mattison, Donald R.

2010-01-01

243

Source identification of ambient PM 2.5 for inhalation exposure studies in Steubenville, Ohio using highly time-resolved measurements  

NASA Astrophysics Data System (ADS)

Recent epidemiological and toxicological studies have suggested that short-term elevations of ambient fine particle mass concentrations (aerodynamic diameter <2.5 ?m, PM 2.5) can increase cardiac and pulmonary health risks. Thus, examining temporal variations of chemical changes in ambient PM 2.5 that could pose the greatest health risks and identifying its sources is critical so that the most toxic categories can be controlled. In this study we collected detailed air quality data in Steubenville, Ohio in August 2006 with the ultimate goal to evaluate associations between cardiovascular (CV) parameters measured in exposed laboratory animals and the chemical and elemental composition of PM 2.5. Current approaches using radiotelemetry to measure CV parameters in conscious laboratory animals are capable of collecting continuous recordings. To provide a robust and analogous dataset that can be better matched with CV responses, we have incorporated a highly time-resolved sampling method to characterize trace elements and thereby obtain more robust input data to determine potential emission sources. We applied positive matrix factorization (PMF) to trace element concentrations from 30-minute ambient PM 2.5 samples in Steubenville, Ohio, an area designated as a non-attainment area for the PM 2.5 National Ambient Air Quality Standards by the Environmental Protection Agency. The average ambient PM 2.5 filter-based mass concentration during the 8-hour summer exposure study period was 26 ± 11 ?g m -3. Results from PMF indicated that six major factors contributed to the ambient PM 2.5 mass during this time: coal combustion/secondary (39 ± 46%), mobile sources (12 ± 14%), metal coating/processing (10 ± 11%), iron and steel manufacturing (5 ± 5%), Pb factor (5 ± 8%), and incineration/smelting (1 ± 3%). The objectives of this paper are (1) to present chemical composition of ambient PM 2.5 and its potential emission sources in Steubenville; and (2) to evaluate the PMF modeling results using observed meteorological data. These semi-continuous sampling approaches to determine potential emission sources have significant advantages over similar analyses using samples averaged over 8-24 h, and are being utilized by our group to determine associations of PM with acute CV responses from animal inhalation toxicology field studies.

Morishita, Masako; Keeler, Gerald J.; Kamal, Ali S.; Wagner, James G.; Harkema, Jack R.; Rohr, Annette C.

2011-12-01

244

Occupational exposure in MRI  

PubMed Central

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

Mcrobbie, D W

2012-01-01

245

Different patterns of regional Purkinje cell loss in the cerebellar vermis as a function of the timing of prenatal ethanol exposure in an ovine model.  

PubMed

Studies in rat models of fetal alcohol spectrum disorders have indicated that the cerebellum is particularly vulnerable to ethanol-induced Purkinje cell loss during the third trimester-equivalent, with striking regional differences in vulnerability in which early-maturing regions in the vermis show significantly more loss than the late-maturing regions. The current study tested the hypothesis that the sheep model will show similar regional differences in fetal cerebellar Purkinje cell loss when prenatal binge ethanol exposure is restricted to the prenatal period of brain development equivalent to the third trimester and also compared the pattern of loss to that produced by exposure during the first trimester-equivalent. Pregnant Suffolk sheep were assigned to four groups: first trimester-equivalent saline control group, first trimester-equivalent ethanol group (1.75 g/kg/day), third trimester-equivalent saline control group, and third trimester-equivalent ethanol group (1.75 g/kg/day). Ethanol was administered as an intravenous infusion on 3 consecutive days followed by a 4-day ethanol-free interval, to mimic a weekend binge drinking pattern. Animals from all four groups were sacrificed and fetal brains were harvested on gestation day 133. Fetal cerebellar Purkinje cell counts were performed in an early-maturing region (lobules I-X) and a late-maturing region (lobules VIc-VII) from mid-sagittal sections of the cerebellar vermis. As predicted, the third trimester-equivalent ethanol exposure caused a significant reduction in the fetal cerebellar Purkinje cell volume density and Purkinje cell number in the early-maturing region, but not in the late-maturing region. In contrast, the first trimester-equivalent ethanol exposure resulted in significant reductions in both the early and late-maturing regions. These data confirmed that the previous findings in rat models that third trimester-equivalent prenatal ethanol exposure resulted in regionally-specific Purkinje cell loss in the early-maturing region of the vermis, and further demonstrated that first trimester ethanol exposure caused more generalized fetal cerebellar Purkinje cell loss, independent of the cerebellar vermal region. These findings support the idea that prenatal ethanol exposure in the first trimester interferes with the genesis of Purkinje cells in an unselective manner, whereas exposure during the third trimester selectively kills post-mitotic Purkinje cells in specific vermal regions during a vulnerable period of differentiation and synaptogenesis. PMID:23195754

Sawant, Onkar B; Lunde, Emilie R; Washburn, Shannon E; Chen, Wei-Jung A; Goodlett, Charles R; Cudd, Timothy A

2013-01-01

246

Military Exposures  

MedlinePLUS

... Enter ZIP code here Enter ZIP code here Military Exposures Veterans may have been exposed to a range of chemical, physical, and environmental hazards during military service. PTSD in OEF/OIF Veterans The New ...

247

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

PubMed

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

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

2013-10-01

248

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...

249

ASSESSING ASTHMATIC CHILDREN'S EXPOSURES TO TOXIC AIR POLLUTANTS AND THE POTENTIAL INHALED DOSES USING TIME ACTIVITY INFORMATION AND ENERGY EXPENDITURE DATA  

EPA Science Inventory

Accurately quantifying human exposures and the potential doses of various populations to environmental pollutants is critical for the U.S. Environmental Protection Agency to assess and manage human health risks. The Tampa Asthmatic Children's Study (TACS) was a pilot research stu...

250

Effects of short time-course exposure to antiandrogen flutamide on steroidogenesis and gene expression in ovary of female fathead minnow (Pimephales promelas)  

EPA Science Inventory

Because the mechanisms through which antiandrogens disrupt reproduction in fish are not well-characterized, this work sought to identify genes and pathways affected by antiandrogen exposure, and to compare differentially expressed genes in the fathead minnow to those previously r...

251

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

SciTech Connect

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.

Gayle Woloschak

2009-12-16

252

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

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…

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

2009-01-01

253

Radiodiagnostic method for studying the dynamics of Anguillicola crassus (Nematoda: Dracunculoidea) infection and pathological status of the swimbladder in Lake Balaton eels.  

PubMed

Swimbladder changes resulting from Anguillicola crassus infection of the European eel Anguilla anguilla have been the subject of several studies reported in the literature. These investigations, however, studied exclusively the status of infection at a given point in time and did not deal with changes in swimbladder infection in eels suffering from anguillicolosis over a period of time. In this study, A. crassus-induced pathological changes were monitored in 78 eels naturally infected in Lake Balaton and subsequently kept in the laboratory, thus excluding the possibility of further infection. During the 3 mo study, the status of the swimbladder was checked by radiographic examination on 4 occasions. At the end of the study the eels were dissected and the gross pathological changes in the swimbladders were compared with the radiographic findings. As compared to their starting condition, by the end of the study the pathological status of the swimbladder had deteriorated in 55% and remained the same in 37% of the cases. Tendency to improvement (1%) and variable findings (7%) were recorded in a low percentage of cases only. With the help of the radiographs presented, the dynamics of A. crassus infection and of changes in the swimbladder of individual eel specimens can be monitored easily. PMID:15900688

Székely, Csaba; Molnár, Kálmán; Rácz, Orsolya Z

2005-04-01

254

For Partner Services, do we need "face-time," or FaceTime?: Trends in Relative Proportion of In-person Notifications and HIV Testing After Introduction of a Telephone Option for HIV Exposure Notification by Public Health.  

PubMed

Public health usually notifies partners of STD exposure in-person despite availability of other options. We examined trends in in-person versus telephone notification for HIV 3 years after the introduction of a telephone option. Most notifications were made by telephone. Partners notified doubled; however, the proportion HIV testing declined slightly. PMID:25299414

Udeagu, Chi-Chi N; Bocour, Angelica; Shepard, Colin W

2014-11-01

255

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  

Microsoft Academic Search

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

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

2002-01-01

256

Mapping occupational heat exposure and effects in South-East Asia: ongoing time trends 1980-2011 and future estimates to 2050.  

PubMed

A feature of climate impacts on occupational health and safety are physiological limits to carrying out physical work at high heat exposure. Heat stress reduces a workers work capacity, leading to lower hourly labour productivity and economic output. We used existing weather station data and climate modeling grid cell data to describe heat conditions (calculated as Wet Bulb Globe Temperature, WBGT) in South-East Asia. During the hottest month in this region (March) afternoon WBGT levels are already high enough to cause major loss of hourly work capacity and by 2050 the situation will be extreme for many outdoor jobs. PMID:23411757

Kjellstrom, Tord; Lemke, Bruno; Otto, Matthias

2013-01-01

257

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

SciTech Connect

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.

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

258

Effects of Prenatal Exposure to a Low Dose Atrazine Metabolite Mixture on Pubertal Timing and Prostate Development of Male Long Evans Rats  

PubMed Central

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. PMID:20727709

Stanko, Jason P.; Enoch, Rolondo R.; Rayner, Jennifer L.; Davis, Christine C.; Wolf, Douglas C.; Malarkey, David E.; Fenton, Suzanne E.

2010-01-01

259

Altered Gene Expression by Low-Dose Arsenic Exposure in Humans and Cultured Cardiomyocytes: Assessment by Real-Time PCR Arrays  

PubMed Central

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 on expression of selected genes in the blood lymphocytes from 159 people exposed chronically to arsenic in their drinking water using a novel RT-PCR TaqMan low-density array (TLDA). We found that expression of tumor necrosis factor-? (TNF-?), which activates both inflammation and NF-?B-dependent survival pathways, was strongly associated with water and urinary arsenic levels. Expression of KCNA5, which encodes a potassium ion channel protein, was positively associated with water and toe nail arsenic levels. Expression of 2 and 11 genes were positively associated with nail and urinary arsenic, respectively. Because arsenic exposure has been reported to be associated with long QT intervals and vascular disease in humans, we also used this TLDA for analysis of gene expression in human cardiomyocytes exposed to arsenic in vitro. Expression of the ion-channel genes CACNA1, KCNH2, KCNQ1 and KCNE1 were down-regulated by 1-?M arsenic. Alteration of some common pathways, including those involved in oxidative stress, inflammatory signaling, and ion-channel function, may underlay the seemingly disparate array of arsenic-associated diseases, such as cancer, cardiovascular disease, and diabetes. PMID:21776218

Mo, Jinyao; Xia, Yajuan; Wade, Timothy J.; DeMarini, David M.; Davidson, Mercy; Mumford, Judy

2011-01-01

260

Exposure control system  

US Patent & Trademark Office Database

An exposure control system includes a device for measuring an intensity of the ambient light, three controllers for controlling three factors of exposure time, aperture size and amount of flash light to be emitted, and a device for setting three pieces of information of film sensitivity and any two of the above mentioned three factors to govern the corresponding two of the three controllers. A calculator is provided for calculating the remaining factor. The calculated value is used for governing the remaining controller. Of the three pieces of information set in the setting device, two pieces can be introduced in a form of a ratio.

1983-01-11

261

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...

262

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

NASA Technical Reports Server (NTRS)

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.

Terrell, J.

1972-01-01

263

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)

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.

Terrell, J.

1973-01-01

264

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  

Microsoft Academic Search

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

Lewis A. Owen; Robert C. Finkel; Patrick L. Barnard; Ma Haizhou; Katsuhiko Asahi; Marc W. Caffee; Edward Derbyshire

2005-01-01

265

Exposure guidelines for magnetic fields  

SciTech Connect

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.

Miller, G.

1987-12-01

266

Preschool teachers’ exposure to classroom noise  

Microsoft Academic Search

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 were subjected to daily noise exposure which, if

Leonid Grebennikov

2006-01-01

267

Wide beam reconstruction for half-dose or half-time cardiac gated SPECT acquisitions: optimization of resources and reduction in radiation exposure  

Microsoft Academic Search

Purpose  A new iterative reconstruction algorithm (WBR™) has been recently proposed for cardiac single photon emission computed tomography\\u000a (SPECT). The WBR™ technology is designed to reduce noise, improving lesion identification without affecting the image resolution,\\u000a allowing SPECT studies with reduced count statistic. This allows for either half-time (HT) or half-dose (HD) cardiac SPECT,\\u000a with image quality and quantitative data comparable to

Claudio Marcassa; Riccardo Campini; Orazio Zoccarato; Paolo Calza

2011-01-01

268

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

PubMed Central

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

Fatima, Nazish

2014-01-01

269

Formaldehyde exposure in a gross anatomy laboratory  

Microsoft Academic Search

A gross anatomy laboratory for medical students was evaluated for formaldehyde levels throughout its eight-week term. Results indicated that exposures for students and instructors were below the 3-ppm permissible exposure limit (assuming a maximum of five hours of daily exposure) established by the Occupational Safety and Health Administration. However, about one third of the eight-hour time-weighted-average exposures were greater than

Jimmy L. Perkins; James D. Kimbrough

1985-01-01

270

Winter 2013 Time Time Time Time Time  

E-print Network

11/8/2012 Winter 2013 Time Time Time Time Time Ugrad Grad Section Lab 590 Ugrad Grad Section Lab/143 quiz sections offered multiple times Thurs. (142) and T/Th (143) Grad courses TBD: 599v1, 517 548 517

Borenstein, Elhanan

271

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

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

Garcia-Leon, Miguel Leonardo; Espinosa-Torres Torrija, Bogart; Hernandez-Perez, Brenda; Cardiel-Marmolejo, Lino E.; Beeler, Judy A.; Audet, Susette; Santos-Preciado, Jose Ignacio

2011-01-01

272

Assessing workplace chemical exposures: the role of exposure monitoring.  

PubMed

Occupational exposure is the condition of being subjected through employment to a chemical, physical, or biological agent, or to a specific process, practice, behavior, or organization of work. Exposure to a chemical agent is typically the contact of that agent with the outer boundary of a subject, such as the respiratory system, skin, or digestive system. In occupational hygiene we are most concerned with exposure through the respiratory system, although, increasingly we are concerned with the results of dermal exposures, including those exposures to the skin that can be transferred to the mouth and digestive system. This presentation will detail methods available for assessing personal exposures to chemicals through monitoring. The results from monitoring can then be compared to established guidelines and regulations, although this is not the only rationale for making measurements. These monitoring methods are currently used around the world to establish the benchmark hazard from which risk to the worker can be predicted. The presentation will describe the general techniques for assessing exposures to the respiratory system from chemical gases and vapors, chemical dusts, and exposures to the skin from bulk chemicals or chemical contamination of surfaces. For respiratory exposures, direct-reading instruments are available for spot measurements, and for monitoring short-term fluctuations in concentration. However, most standards and regulations are based on time-integrated (time-weighted average) exposures, requiring longer-term integrative methods. Therefore, the specific focus of this review will be the methods available for full work-shift sampling. For gases and vapors this will include taking whole-air samples in canisters or polymer bags, or concentration of chemicals by absorption in liquids or adsorption on solid sorbents, with subsequent chemical analysis. Chemical concentration can take place by pumping air through the sorbing media, or by allowing molecules to diffuse to the sorbent surface. Transfer of the collected chemicals to the analytical instrumentation can be accomplished using solvent displacement and injection, or through the application of heat to bring the collected molecules back into the vapor phase. For particles, the particle size is important as this determines the site of deposition in the lungs, and so time-integrated sampling on filters using various types of size-selective samplers is preferred. Finally, some techniques that have been used to assess the potential for chemical contamination of the skin are presented. Biomonitoring is another tool that can be used to assess exposure, and the results are more relevant to dosimetric considerations than exposure. Biomonitoring is a complex subject worthy of a separate review, and will be considered only briefly here. PMID:15152307

Harper, Martin

2004-05-01

273

Environmental exposure tracking sensor  

NASA Astrophysics Data System (ADS)

Cornerstone Research Group Inc. (CRG) has developed environmental exposure tracking (EET) sensors using shape memory polymer (SMP) to monitor the degradation of perishable items, such as munitions, medicines or foods, by measuring the cumulative exposure to temperature and moisture. SMPs are polymers whose qualities have been altered to give them dynamic shape "memory" properties. Under thermal or moisture stimuli, SMP exhibits a radical change from a rigid thermoset to a highly flexible, elastic state. The dynamic response of the SMP can be tailored to match the degradation profile of the perishable item. SMP-based EET sensors require no digital memory or internal power supply and provide the capability of inexpensive, long-term life cycle monitoring thermal and moisture exposure over time. In a Phase I and II SBIR effort with the Navy, CRG demonstrated the feasibility of SMP-based EET sensor with two material systems. These material systems required different activation stimuli, heat or water vapor pressure. CRG developed the ability to tailor these materials to customize the dynamic response to match various degradation profiles of munitions. CRG optimized and characterized the SMP formulations and sensor design configuration to develop a suite of data from which any degradation profile can be met. CRG's EET sensors are capable of monitoring temperatures from -30 °C to 260 °C. The prototypes monitor cumulative thermal exposure and provide real-time information in a visually readable or a remotely interrogated version. CRG is currently scaling up the manufacture of the sensors for munitions reliability applications with the Navy.

Havens, Teresa; Everhart, Joel; McFerran, Jace

2009-03-01

274

Radiation Exposure  

MedlinePLUS

... particles. It occurs naturally in sunlight. Man-made radiation is used in X-rays, nuclear weapons, nuclear power plants and cancer treatment. If you are exposed to small amounts of radiation over a long time, it raises your risk ...

275

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

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).

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

1990-06-01

276

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...

277

Radiation Contamination Versus Exposure  

MedlinePLUS

RADIATION CONTAMINATION VERSUS EXPOSURE EXTERNAL CONTAMINATION External contamination occurs when radioactive material comes into contact with a ... radioactive materials can accumulate in different body organs. RADIATION EXPOSURE Another word for radiation exposure is irradiation. ...

278

Northern exposure.  

PubMed

The operators of Alaska's Alyeska pipeline have often claimed an outstanding record in preventing accidents and environmental damage. This article highlights that, contrary to these claims, Alyeska's operations have brought with them a life-threatening gamble with Alaska's fragile environment. The authors document how the operators of Alyeska have misled the public about the company's real safety record, while at the same time preventing employees from speaking out. As the oil companies consolidate globally, territorial entities such as Alaska can literally assume the character of an oil province. PMID:17208848

Gillard, M; Jones, M; Rowell, A

2000-01-01

279

OCCUPATIONAL EXPOSURE TO FORMALDEHYDE IN A MEDICAL CENTER AUTOPSY SERVICE  

EPA Science Inventory

The formaldehyde exposure occurring in the autopsy service of a medical complex were evaluated as part of a study to detect genetically harmful effects of chemical exposures. Determination of time-weighted average (TWA) exposures and characterization of the patterns of exposure e...

280

Inhalation exposure of animals.  

PubMed Central

Relative advantages and disadvantages and important design criteria for various exposure methods are presented. Five types of exposures are discussed: whole-body chambers, head-only exposures, nose or mouth-only methods, lung-only exposures, and partial-lung exposures. Design considerations covered include: air cleaning and conditioning; construction materials; losses of exposure materials; evenness of exposure; sampling biases; animal observation and care; noise and vibration control, safe exhausts, chamber loading, reliability, pressure fluctuations; neck seals, masks, animal restraint methods; and animal comfort. Ethical considerations in use of animals in inhalation experiments are also discussed. PMID:1017420

Phalen, R F

1976-01-01

281

Formaldehyde exposure in a gross anatomy laboratory  

SciTech Connect

A gross anatomy laboratory for medical students was evaluated for formaldehyde levels throughout its eight-week term. Results indicated that exposures for students and instructors were below the 3-ppm permissible exposure limit (assuming a maximum of five hours of daily exposure) established by the Occupational Safety and Health Administration. However, about one third of the eight-hour time-weighted-average exposures were greater than 1 ppm under the same assumptions. Exposure levels for students and instructors did not differ. Exposures tended to decrease over the term unless internal cadaver cavities were being dissected. These exposures are significant in light of the recent implication of formaldehyde as an animal carcinogen and the trend to reduce permissible levels to 1 ppm or lower.

Perkins, J.L.; Kimbrough, J.D.

1985-11-01

282

Occupational exposure to polychlorinated biphenyls (PCBs).  

PubMed Central

Human occupational exposure to polychlorinated biphenyls (PCBs) with varying chlorine content has been reported by several investigators, using analyses of blood or adipose samples or skin wipes to evaluate levels in the body. The intensity of occupational exposure is related to both duration and intensity of exposure. The qualitative nature of occupational exposure, as well as casual environmental exposure, has been shown to consist of less readily metabolized PCB congeners. The pattern of PCB congeners in human tissues, determined by gas chromatography, may or may not be readily ascribed to specific PCB standard mixtures. The average occupational exposure, as depicted in several studies of blood, plasma or serum concentrations, is approximately 10 to 1000 times that observed in nonoccupationally exposed persons. Currently used methods of PCB quantitation and pattern identification vary widely, with no uniformly administered criteria being applied to characterize human PCB exposure. PMID:3928344

Wolff, M S

1985-01-01

283

Personal exposure to ultrafine particles.  

PubMed

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

Wallace, Lance; Ott, Wayne

2011-01-01

284

Evaluation of personal exposure to monoaromatic hydrocarbons  

PubMed Central

OBJECTIVES: To evaluate the personal exposure of members of the general public to atmospheric benzene, toluene, and the xylenes, excluding exposure from active smoking. METHOD: 50 volunteers were equipped with active air samplers for direct measurement of personal exposure to monoaromatic hydrocarbons (MAH) and an activity diary was completed during each sampling period. Exposures were also estimated indirectly by combining activity data with independent measurements of hydrocarbon concentrations in several microenvironments. RESULTS: Personal exposure were generally well in excess of those which would be inferred from outdoor measurements from an urban background monitoring station. A wide range of sources contribute to exposure, with indoor and in car concentrations generally exceeding those measured at background outdoor locations. Environments contaminated with tobacco smoke were among those exhibiting the highest concentrations. Personal exposures determined indirectly from activity diaries/microenvironment measurements were well correlated with those determined directly with personal samplers. Personal 12 hour daytime exposures to benzene ranged from 0.23-88.6 ppb (mean 3.81 ppb), with 12 hour night time exposures of 0.61-5.67 ppb (mean 1.94 ppb) compared with an annual average concentration of 1.18 ppb at the nearest suburban fixed site monitoring station. The excess of personal exposure over fixed site concentrations was greater for benzene and toluene than for the xylenes. CONCLUSION: A wide range of sources contribute to personal exposures to monoaromatic hydrocarbons with exposure duration being as important a determinant of total exposure as concentrations. Exposures generally exceed those estimated from concentrations measured by background fixed point monitors. Microenvironment sampling combined with activity diary information can provide satisfactory estimates of personal exposure to these compounds.   PMID:9624279

Leung, P. L.; Harrison, R. M.

1998-01-01

285

SILICA EXPOSURE IN HAND GRINDING STEEL CASTINGS  

Microsoft Academic Search

Exposure to silica dust was studied in the grinding of castings in a steel foundry that used conventional personal sampling methods and new real-time sampling techniques developed for the identification of high-exposure tasks and tools. Approximately one-third of the personal samples exceeded the National Institute for Occupational Safety and Health recommended exposure limit for crystalline silica, a fraction similar to

Dennis OBrien; Phillip A. Froehlich; Michael G. Gressel; Ronald M. Hall; Nancy J. Clark; Patrick Bost; Thomas Fischbach

1992-01-01

286

Sun exposure at school.  

PubMed

There is strong evidence that sun exposure during childhood and adolescence plays an important role in the etiology of skin cancer, in particular cutaneous melanoma. Between the age of 6 and 18, most children and adolescents will spend around 200 days per year at school and may receive a substantial fraction of their daily total solar ultraviolet radiation (UVR) exposure while at school. This study estimated the average daily erythemally effective dose of 70 grade 8 students from a high school in Townsville during 5 school days in July 1998. Through UV measurements of shade locations at the school and a combination of frequency counts and a questionnaire of grade 8 students, it was possible to determine the fraction of solar UVR reaching under the shade structures during lunch breaks and routine outdoor activities. Also, a routinely operating UV-Biometer provided the annual variation of the daily dose that was used to calculate exposure levels for the 70 students. Our results suggest that up to 47% of the daily total dose fell within the time periods where students were outdoors during school hours. For students not seeking shade structures during the breaks (which usually was the case when involved in sport activities such as basketball or soccer), the average daily dose could have been as high as 14 SED (standard erythemal dose). Using results from the questionnaire of 70 grade 8 students, their average annual dose while at school was 414 SED or 2 SED per school day. However, the distribution of average daily erythemal effective dose per grade 8 student over the whole year showed that on 31% of all school days in 1998, this dose was exceeded. Because most previous attempts to change arguably poor sun-protective behavior of young Australian children and adolescents at school showed little success, one way of decreasing the amount of harmful UVR reaching unprotected skin is the more careful design of shade structures at schools. PMID:10461467

Moise, A F; Büttner, P G; Harrison, S L

1999-08-01

287

Multi-plate, multi-exposure stellar calibration  

Microsoft Academic Search

A series of field and data reduction procedures have been developed to obtain highly accurate camera calibration constants for metric reseau cameras from time exposures of the star field. The calibration techniques include combined data from several two-and-one-half hour chopped and precisely timed exposures. Each exposure is made with the camera rigidly mounted and oriented to a different direction about

L. W. Fritz; C. C. Slama

1976-01-01

288

Biomarker of pyrethrum exposure.  

PubMed

Pyrethrum as well as synthetic pyrethroids like allethrin, resmethrin, phenothrin, tetramethrin, cyfluthrin, cypermethrin, deltamethrin or permethrin are among the insecticides most often used worldwide. With a sensitive and valid gas-chromatographic-high resolution mass spectrometric method, it is possible to detect all pyrethrum and pyrethroid metabolites in one analytical run. Thus, for the first time a background level of trans-chrysanthemumdicarboxylic acid (CDCA) in urine (95th percentile: 0.15 microg/l) as a characteristic, e.g. for a pyrethrum exposure was found. Following a pyrethrum exposure lasting 1 day, CDCA was found in 27 out of 30 subjects with concentrations going up to 54 microg/l urine (mean: 1.1+/-4.4 microg/l). To obtain information about the elimination kinetics of pyrethrum in humans, urinary excretion of CDCA was investigated in three volunteers after oral intake of 0.3mg pyrethrin I. CDCA was detected during the first 36 h after intake with elimination being most rapid during the first 4h (mean elimination half-life: 4.2h). PMID:16257148

Leng, Gabriele; Gries, Wolfgang; Selim, Sami

2006-04-10

289

IMPACT OF EMISSION REDUCTIONS ON EXPOSURES AND EXPOSURE DISTRIBUTIONS: APPLICATION OF A GEOGRAPHIC EXPOSURE MODEL  

EPA Science Inventory

Anticipated results include the following. (1) We will estimate intake fraction (i.e., the fraction of emissions that are inhaled) for major source categories, over time, and by spatial location. Higher intake fraction indicates a greater exposure reduction per emission reduct...

290

Adolescent Exposure to Food Advertising on Television  

Microsoft Academic Search

Results: The results showed that among total nonprogram content time, food-related products accounted for roughly one fifth of advertising exposure. Excluding TV promotions and public service announcements, as a proportion of all product advertising, total food-related advertising made up 26% of advertised products viewed by adolescents. By race, the proportion of advertising exposure to food products was 14% greater for

Lisa M. Powell; Glen Szczypka; Frank J. Chaloupka

2007-01-01

291

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 ...

292

Understanding Greek Primary School Children's Comprehension of Sun Exposure.  

ERIC Educational Resources Information Center

Assesses Greek primary school children's understanding of sun exposure during summer vacation. Results indicate that children know the damaging effects of long time exposure and the precautions that should be taken during summer bathing. (Author/SOE)

Piperakis, Stylianos M.; Papadimitriou, Vasiliki; Piperakis, Michael M.; Zisis, Panagiotis

2003-01-01

293

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...

294

SUPERFUND EXPOSURE ASSESSMENT MANUAL  

EPA Science Inventory

Manual provides a framework for the assessment of exposure to contaminants at or migrating from uncontrolled hazardous waste sites, covering the application of both monitoring and modeling procedures to the exposure assessment process. This process considers all contaminant relea...

295

Dangers of Radiation Exposure  

NSDL National Science Digital Library

In the first part of the lesson, students calculate their yearly exposure rate to harmful high-energy radiation and cumulative effects over time. They then use the information to evaluate the various sources of radiation that are of greatest concern for them. In the second part of the lesson, students learn that spacecraft and other objects in space must be concerned with the same kinds of radiation to which humans are exposed. The MESSENGER spacecraft will orbit Mercury and be subjected to much more intense solar radiation than it would near Earth. Students discuss the notion that even though some of the radiation is needed to study the properties of the planet, too much of it can be quite damaging.

American Association for the Advancement of Science (AAAS;)

2005-03-15

296

Opioid Antagonist Impedes Exposure.  

ERIC Educational Resources Information Center

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…

Merluzzi, Thomas V.; And Others

1991-01-01

297

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...

298

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...

299

Exposure scenarios for workers  

Microsoft Academic Search

The new European chemicals legislation REACH (Registration, Evaluation, Authorisation and restriction of Chemicals) requires the development of Exposure Scenarios describing the conditions and risk management measures needed for the safe use of chemicals. Such Exposure Scenarios should integrate considerations of both human health and the environment. Specific aspects are relevant for worker exposure. Gathering information on the uses of the

Hans Marquart; Christine Northage; Chris Money

2007-01-01

300

Biological Response to SPE Exposures  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

301

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...

302

Farm Family Exposure Study: methods and recruitment practices for a biomonitoring study of pesticide exposure  

Microsoft Academic Search

Purpose:The Farm Family Exposure Study was initiated to characterize pesticide exposure to farm family members around the time of one pesticide application in a manner that will facilitate exposure assessment in epidemiologic studies of pesticides.Methods:A sample of farm families with children was recruited by randomly selecting farmers from lists of licensed pesticide applicators in Minnesota and South Carolina. Eligible families

Beth A Baker; Bruce H Alexander; Jack S Mandel; John F Acquavella; Richard Honeycutt; Pamela Chapman

2005-01-01

303

Postnatal Exposure History and Airways  

PubMed Central

Postnatally, the lung continues to grow and differentiate while interacting with the environment. Exposure to ozone (O3) and allergens during postnatal lung development alters structural elements of conducting airways, including innervation and neurokinin abundance. These changes have been linked with development of asthma in a rhesus monkey model. We hypothesized that O3 exposure resets the ability of the airways to respond to oxidant stress and that this is mediated by changes in the neurokinin-1 receptor (NK-1R). Infant rhesus monkeys received episodic exposure to O3 biweekly with or without house dust mite antigen (HDMA) from 6 to 12 months of age. Age-matched monkeys were exposed to filtered air (FA). Microdissected airway explants from midlevel airways (intrapulmonary generations 5–8) for four to six animals in each of four groups (FA, O3, HDMA, and HDMA+O3) were tested for NK-1R gene responses to acute oxidant stress using exposure to hydrogen peroxide (1.2 mM), a lipid ozonide (10 ?M), or sham treatment for 4 hours in vitro. Airway responses were measured using real-time quantitative RT-PCR of NK-1R and IL-8 gene expression. Basal NK-1R gene expression levels were not different between the exposure groups. Treatment with ozonide or hydrogen peroxide did not change NK-1R gene expression in animals exposed to FA, HDMA, or HDMA+O3. However, treatment in vitro with lipid ozonide significantly increased NK-1R gene expression in explants from O3–exposed animals. We conclude that a history of prior O3 exposure resets the steady state of the airways to increase the NK-1R response to subsequent acute oxidant stresses. PMID:22962062

Murphy, Shannon R.; Schelegle, Edward S.; Edwards, Patricia C.; Miller, Lisa A.; Hyde, Dallas M.

2012-01-01

304

Loud noise exposure and acoustic neuroma.  

PubMed

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

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

305

Reconstruction of occupational mercury exposures at a chloralkali plant  

PubMed Central

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

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

2001-01-01

306

Occupational Exposure to Metalworking Fluid Mist and Sump Fluid Contaminants  

Microsoft Academic Search

This paper summarizes the analytical and occupational hygiene findings from a recent survey of occupational exposure to metalworking fluids (MWFs) in the engineering industry. The aim of the survey was to link MWF mist exposure measurements with particular engineering processes and controls, and utilize the data obtained to develop exposure standards. At the same time the opportunity was taken to

A. T. SIMPSON; M. STEAR; J. A. GROVES; M. PINEY; S. D. BRADLEY; S. STAGG; B. CROOK

2003-01-01

307

EXPOSURES TO ENVIRONMENTAL AGENTS  

EPA Science Inventory

The planned interagency National Children's Study (NCS) will be studying a number of exposure issues in the context of health and well-being of infants and young children from pre-conception to age 21. Some of the important environmental exposure questions for NCS, include: how c...

308

Exchange rate exposure  

Microsoft Academic Search

In this paper we examine the relationship between exchange rate movements and firm value. We estimate the exchange rate exposure of publicly listed firms in a sample of eight (non-US) industrialized and emerging markets. We find that exchange rate movements do matter for a significant fraction of firms, though which firms are affected and the direction of exposure depends on

Kathryn M. E. Dominguez; Linda L. Tesar

2006-01-01

309

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...

310

Exposure Factors Program  

EPA Science Inventory

The development of the latest version of the Exposure Factors Handbook (EFH): 2011 Edition (EPA/600/R-09/052F) has maintained the need for a more comprehensive program that addresses issues related to exposure factors. Since the first version of the EFH was r...

311

Radiation Exposure Compensation Program  

NSDL National Science Digital Library

This is the Justice Department's Radiation Exposure Compensation Program homepage. This site features information about the Radiation Exposure Compensation Act, including claimant categories, claim forms, and the Energy Employees Occupational Illness Compensation Program Act. This site also provides a table illustrating a summary of all claims received and compensation paid to date.

Program, U. S.

312

Human occupational and nonoccupational exposure to fibers.  

PubMed Central

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

Esmen, N A; Erdal, S

1990-01-01

313

Respiratory exposures associated with silicon carbide production: estimation of cumulative exposures for an epidemiological study.  

PubMed

Silicon carbide is produced by heating a mixture of petroleum coke and silica sand to approximately 2000 degrees C in an electric furnace for 36 hours. During heating, large amounts of carbon monoxide are released, sulphur dioxide is produced from residual sulphur in the coke, and hydrocarbon fume is produced by pyrolysis of the coke. Loading and unloading furnaces causes exposures to respirable dust containing crystalline silica, silicon carbide, and hydrocarbons. In the autumn of 1980 extensive measurements were made of personal exposures to air contaminants. Eight hour time weighted exposures to sulphur dioxide ranged from less than 0.1 ppm to 1.5 ppm and respirable participate exposures ranged from 0.01 mg/m3 to 9.0 mg/m3. Geometric mean particulate exposures for jobs ranged from 0.1 mg/m3 to 1.46 mg/m3. The particulate contained varying amounts of alpha-quartz, ranging from less than 1% to 17%, and most quartz exposures were substantially below the threshold limit value of 100 micrograms/m3. Only traces of cristobalite (less than 1%) were found in the particulate. Median exposures to air contaminants in each job were estimated. Since the operations at the plant had been stable over the past 30 years, it was possible to estimate long term exposures of workers to sulphur dioxide, respirable particulate, quartz, total inorganic material, and extractable organic material. Cumulative exposure (average concentration times exposure duration) for each of the air contaminants was estimated for each worker using his job history. There was sufficient independent variability in the sulphur dioxide and respirable particulate cumulative exposures to make an assessment of their independent effects feasible. The theoretical basis for using the cumulative exposure index and its shortcomings for epidemiological applications were presented. PMID:6691927

Smith, T J; Hammond, S K; Laidlaw, F; Fine, S

1984-02-01

314

Estimating long-term exposures from short-term measurements.  

PubMed

Many health problems are related to chronic exposure of individuals to pollutants in the environment. The level of exposure of a specified population is typically represented by the mean level of exposure of the population, the variation in exposure between individuals within the population, and levels of exposure for selected percentiles of the population, such as the 50th and 98th percentiles. However, the day-to-day level of exposure for individuals varies, and direct measurement of total exposure for long periods of time is impractical. The problem is to estimate the quantities listed above using incomplete sampling of the time period of interest. This paper looks at the effect of using estimates of long-term exposure for individuals on estimating the exposure distribution of the population. A simple and apparently robust estimate for the upper percentiles of the exposure distribution is proposed. Problems related to estimating an individual's long-term exposure, including sample size, are also discussed. The length of time defined as long-term in this paper is one year; however, the results are generalizable to any period of time desired. PMID:8814776

Buck, R J; Hammerstrom, K A; Ryan, P B

1995-01-01

315

High Exposure Facility Technical Description  

SciTech Connect

The High Exposure Facility is a collimated high-level gamma irradiator that is located in the basement of the 318 building. It was custom developed by PNNL back in 1982 to meet the needs for high range radiological instrument calibrations and dosimeter irradiations. At the time no commercially available product existed that could create exposure rates up to 20,000 R/h. This document is intended to pass on the design criteria that was employed to create this unique facility, while maintaining compliance with ANSI N543-1974, "General Safety Standard for Installations Using Non-Medical X-Ray and Sealed Gamma-Ray Sources, Energies up to 10 MeV."

Carter, Gregory L.; Stithem, Arthur R.; Murphy, Mark K.; Smith, Alex K.

2008-02-12

316

Male gonadal dose of ionizing radiation delivered during X-ray examinations and monthly probability of pregnancy: a population-based retrospective study  

PubMed Central

Background Male gonadal exposure to ionizing radiation may disrupt spermatogenesis, but its influence on the fecundity of couples has been rarely studied. We aimed to characterize the influence of male gonadal dose of ionizing radiation delivered during radiodiagnostic on the monthly probability of pregnancy. Methods We recruited a random sample of women who retrospectively described 1110 periods of unprotected intercourse beginning between 1985 and 1999 and leading either to a live birth or to no pregnancy; their duration was censored after 13 months. The male partner answered a telephone questionnaire on radiodiagnostic examinations. We assigned a mean gonadal dose to each type of radiodiagnostic examination. We defined male dose for each period of unprotected intercourse as the sum of the gonadal doses of the X-ray examinations experienced between 18 years of age and the date of discontinuation of contraception. Time to pregnancy was analysed using a discrete Cox model with random effect allowing to estimate hazard ratios of pregnancy. Results After adjustment for female factors likely to influence fecundity, there was no evidence of an association between male dose and the probability of pregnancy (test of homogeneity, p = 0.55). When compared to couples with a male gonadal dose between 0.01 and 0.20 milligrays (n = 321 periods of unprotected intercourse), couples with a gonadal dose above 10 milligrays had a hazard ratio of pregnancy of 1.44 (95% confidence interval, 0.73–2.86, n = 31). Conclusion Our study provides no evidence of a long-term detrimental effect of male gonadal dose of ionizing radiation delivered during radiodiagnostic on the monthly probability of pregnancy during the year following discontinuation of contraceptive use. Classification errors due to the retrospective assessment of male gonadal exposure may have limited the statistical power of our study. PMID:16515681

Sinno-Tellier, Sandra; Bouyer, Jean; Ducot, Beatrice; Geoffroy-Perez, Beatrice; Spira, Alfred; Slama, Remy

2006-01-01

317

Phthalates: toxicology and exposure.  

PubMed

Phthalates are used as plasticizers in PVC plastics. As the phthalate plasticizers are not chemically bound to PVC, they can leach, migrate or evaporate into indoor air and atmosphere, foodstuff, other materials, etc. Consumer products containing phthalates can result in human exposure through direct contact and use, indirectly through leaching into other products, or general environmental contamination. Humans are exposed through ingestion, inhalation, and dermal exposure during their whole lifetime, including intrauterine development. This paper presents an overview on current risk assessments done by expert panels as well as on exposure assessment data, based on ambient and on current human biomonitoring results. Some phthalates are reproductive and developmental toxicants in animals and suspected endocrine disruptors in humans. Exposure assessment via modelling ambient data give hints that the exposure of children to phthalates exceeds that in adults. Current human biomonitoring data prove that the tolerable intake of children is exceeded to a considerable degree, in some instances up to 20-fold. Very high exposures to phthalates can occur via medical treatment, i.e. via use of medical devices containing DEHP or medicaments containing DBP phthalate in their coating. Because of their chemical properties exposure to phthalates does not result in bioaccumulation. However, health concern is raised regarding the developmental and/or reproductive toxicity of phthalates, even in environmental concentrations. PMID:17889607

Heudorf, Ursel; Mersch-Sundermann, Volker; Angerer, Jürgen

2007-10-01

318

Asbestos exposure in buildings.  

PubMed

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. To these uncertainties must be added the unproved assumption of a linear dose-response down to very low levels of exposure with no threshold. At the other end of the scale extrapolation has required measurements of present building exposure, and these have been revised downward as methods for collection and analysis have improved. Risk estimates in this country and abroad have assumed exposure to 0.001 f/mL, with indicated lifetime risks for cancer ranging from about 2 to 20 per 1 million students. However, these estimates have assumed mixed fiber exposure whereas most building exposure comes from chrysotile, which is much less toxic than the amphiboles.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1511551

Gaensler, E A

1992-06-01

319

Nuclear Energy: Radiation Exposure  

NSDL National Science Digital Library

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.

Pratte, John

320

Personal exposure of children to air pollution  

NASA Astrophysics Data System (ADS)

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.

Ashmore, M. R.; Dimitroulopoulou, C.

321

Estimating Exposure of Terrestrial Wildlife to Contaminants  

SciTech Connect

This report presents a general model for exposure of terrestrial wildlife to contaminants (Sect. 2), methods for estimating parameters of the model (Sect. 3), species specific parameters for endpoint species on the Oak Ridge Reservation (ORR) (Sect. 4), and a sample application (Sect. 5). Exposure can be defined as the coincidence in both space and time of a receptor and a stressor, such that the receptor and stressor come into contact and interact (Risk Assessment Forum 1992). In the context of ecological risk assessment, receptors include all endpoint species or communities identified for a site [see Suter (1989) and Suter et al. (1994) for discussions of ecological endpoints for waste sites]. In the context of waste site assessments, stressors are chemical contaminations, and the contact and interaction are uptake of the contaminant by the receptor. Without sufficient exposure of the receptor to the contaminants, there is no ecological risk. Unlike some other endpoint assemblages, terrestrial wildlife are significantly exposed to contaminants in multiple media. They may drink or swim in contaminated water, ingest contaminated food and soil, and breath contaminated air. In addition, because most wildlife are mobile, moving among and within habitats, exposure is not restricted to a single location. They may integrate contamination from several spatially discrete sources. Therefore, exposure models for terrestrial wildlife must include multiple media. This document provides models and parameters for estimating exposure of birds and mammals. Reptiles and amphibians are not considered because few data exist with which to assess exposure to these organisms. In addition, because toxicological data are scarce for both classes, evaluation of the significance of exposure estimates is problematic. However, the general exposure estimation procedure developed herein for birds and mammals is applicable to reptiles and amphibians. Exposure models must be appropriate to the assessment endpoints. The models presented herein are models of the exposure of individual organisms, but except for threatened and endangered species, all the wildlife endpoints for the ORR are for populations (Suter et al. 1994). The use of organism exposures is appropriate because of the need to integrate exposure estimates with exposure-response information which is expressed as organism-level responses. The conversion of individual exposure to population effects occurs in the risk characterization. Conceptually, the conversion of organism-level exposures to the population level can be made in two ways. First, it may be assumed that there is a distinct population on the site so that the exposure of the population is the exposure of all the individuals. This assumption is appropriate for small organisms on large sites, particularly if the site constitutes a distinct habitat that is surrounded by inappropriate habitat. For example, a grassy site surrounded by forest or industrial development might support a distinct population of voles. The risks to that population can be estimated directly from the exposures of the individual organisms. Second, it may be assumed that a certain number of individuals are exposed to contaminants out of a larger population. For example, a certain proportion of a deer herd may forage on a site or a pair of hawks may hunt on a site. The estimated exposure of these individuals will result in estimation of certain effects on those individuals, and the resulting population risks will need to be characterized. In either case, the organism level exposure models are appropriate.

Sample, B.E.

1994-01-01

322

Benzene and total hydrocarbons exposures in the downstream petroleum industries.  

PubMed

A review of studies, including both articles published in peer-reviewed journals and reports that were not peer reviewed, regarding occupational exposure to benzene and total hydrocarbons in the downstream petroleum industry operations was performed. The objective was to provide a broad estimate of exposures by compiling exposure data according to the following categories: refinery, pipeline, marine, rail, bulk terminals and trucks, service stations, underground storage tanks, tank cleaning, and site remediations. The data in each category was divided into personal occupational long-term and short-term samples. The summarized data offers valuable assistance to hygienists by providing them with an estimate and range of exposures. The traditional 8-hour time-weighted average (TWA) exposure and the 40-hour workweek do not generally coincide with exposure periods applicable to workers in marine, pipeline, railcar, and trucking operations. They are more comparable with short-term exposure or task-based exposure assessments. The marine sector has a large number of high exposures. Although relatively few workers are exposed, their exposures to benzene and total hydrocarbons are sometimes an order of magnitude higher than the respective exposure limits. It is recommended that in the future, it would be preferable to do more task-based exposure assessments and fewer traditional TWA long-term exposure assessments within the various sectors of the downstream petroleum industry. PMID:11331990

Verma, D K; Johnson, D M; Shaw, M L; des Tombe, K

2001-01-01

323

Does Exposure Imitate Art?  

EPA Science Inventory

A presentation on the transformation in exposure science, similar to the transformation from realism to impressionism, which is required to realize the potential of NRC's vision for toxicity testing....

324

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.

325

[Dermal exposure and absorption].  

PubMed

Dermal exposure assessment explores the dynamic interaction between environmental contaminants and the skin. The measure of skin exposure can be made using direct methods (interception techniques, removal techniques from skin, in situ detection) or indirect methods (biological monitoring, removal techniques from surfaces). The selection of the appropriate sampling method will depend on a range of factors (the sampling objectives, the compartment or transport process of interest, the nature of the agent and the analytical methods to be used) and should be part of a coherent and documented sampling strategy. In this work we describe the processes leading to exposure, in relation to the presence of clothing or protective garments, discuss on factors that influence skin penetration (both the physiologic characteristics of the skin and the physico-chemical nature of the compound that comes into contact with the skin) with the purpose to assess and manage the risk of skin exposure. PMID:21438233

Aprea, M C

2010-01-01

326

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 ...

327

Electromagnetic Field Exposure Dosimeter.  

National Technical Information Service (NTIS)

The growing concern about adverse health effects caused by electromagnetic radiation prompted the ideas for this dosimeter. Data have been presented that ink prolonged exposure to electromagnetic radiation from power lines to leukemia and some types of ca...

A. C. Feaga, M. P. Hilliard, R. Link

1994-01-01

328

Radiation exposure and pregnancy.  

PubMed

Radiological exposure from nuclear power reactor accidents, transportation of nuclear waste accidents, industrial accidents, or terrorist activity may be a remote possibility, but it could happen. Nurses must be prepared to evaluate and treat pregnant women and infants who have been exposed to radiation, and to have an understanding of the health consequences of a nuclear or radiological incident. Pregnant women and infants are a special group of patients who need consideration when exposed to radiation. Initial care requires thorough assessment and decisions regarding immediate care needs. Ongoing care is based on type and extent of radiation exposure. With accurate, comprehensive information and education, nurses will be better prepared to help mitigate the effects of radiation exposure to pregnant women and infants following a radiological incident. Information about radiation, health effects of prenatal radiation exposure, assessment, patient care, and treatment of pregnant women and infants are presented. PMID:25333800

Labant, Amy; Silva, Christina

2014-01-01

329

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...

330

Nanotechnology and Exposure Science  

PubMed Central

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

LIOY, PAUL J.; NAZARENKO, YEVGEN; HAN, TAE WON; LIOY, MARY JEAN; MAINELIS, GEDIMINAS

2014-01-01

331

Particle exposures and infections.  

PubMed

Particle exposures increase the risk for human infections. Particles can deposit in the nose, pharynx, larynx, trachea, bronchi, and distal lung and, accordingly, the respiratory tract is the system most frequently infected after such exposure; however, meningitis also occurs. Cigarette smoking, burning of biomass, dust storms, mining, agricultural work, environmental tobacco smoke (ETS), wood stoves, traffic-related emissions, gas stoves, and ambient air pollution are all particle-related exposures associated with an increased risk for respiratory infections. In addition, cigarette smoking, burning of biomass, dust storms, mining, and ETS can result in an elevated risk for tuberculosis, atypical mycobacterial infections, and meningitis. One of the mechanisms for particle-related infections includes an accumulation of iron by surface functional groups of particulate matter (PM). Since elevations in metal availability are common to every particle exposure, all PM potentially contributes to these infections. Therefore, exposures to wood stove emissions, diesel exhaust, and air pollution particles are predicted to increase the incidence and prevalence of tuberculosis, atypical mycobacterial infections, and meningitis, albeit these elevations are likely to be small and detectable only in large population studies. Since iron accumulation correlates with the presence of surface functional groups and dependent metal coordination by the PM, the risk for infection continues as long as the particle is retained. Subsequently, it is expected that the cessation of exposure will diminish, but not totally reverse, the elevated risk for infection. PMID:24488331

Ghio, A J

2014-06-01

332

Autoimmunity and asbestos exposure.  

PubMed

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

Pfau, Jean C; Serve, Kinta M; Noonan, Curtis W

2014-01-01

333

Autoimmunity and Asbestos Exposure  

PubMed Central

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

Pfau, Jean C.; Serve, Kinta M.; Noonan, Curtis W.

2014-01-01

334

Thirdhand Cigarette Smoke: Factors Affecting Exposure and Remediation  

PubMed Central

Thirdhand smoke (THS) refers to components of secondhand smoke that stick to indoor surfaces and persist in the environment. Little is known about exposure levels and possible remediation measures to reduce potential exposure in contaminated areas. This study deals with the effect of aging on THS components and evaluates possible exposure levels and remediation measures. We investigated the concentration of nicotine, five nicotine related alkaloids, and three tobacco specific nitrosamines (TSNAs) in smoke exposed fabrics. Two different extraction methods were used. Cotton terry cloth and polyester fleece were exposed to smoke in controlled laboratory conditions and aged before extraction. Liquid chromatography-tandem mass spectrometry was used for chemical analysis. Fabrics aged for 19 months after smoke exposure retained significant amounts of THS chemicals. During aqueous extraction, cotton cloth released about 41 times as much nicotine and about 78 times the amount of tobacco specific nitrosamines (TSNAs) as polyester after one hour of aqueous extraction. Concentrations of nicotine and TSNAs in extracts of terry cloth exposed to smoke were used to estimate infant/toddler oral exposure and adult dermal exposure to THS. Nicotine exposure from THS residue can be 6.8 times higher in toddlers and 24 times higher in adults and TSNA exposure can be 16 times higher in toddlers and 56 times higher in adults than what would be inhaled by a passive smoker. In addition to providing exposure estimates, our data could be useful in developing remediation strategies and in framing public health policies for indoor environments with THS. PMID:25286392

Bahl, Vasundhra; Jacob, Peyton; Havel, Christopher; Schick, Suzaynn F.; Talbot, Prue

2014-01-01

335

Commuters’ air pollution exposure and acute health effects  

Microsoft Academic Search

People spend a substantial proportion of their time in traffic. In Europe, the average daily time in traffic is one to one and a half hour. Because of high in-traffic exposures and because most of the journeys are made during rush hours, the one to one and a half hour in traffic contributes disproportionately to total daily exposure to traffic

M. M. M. Zuurbier

2011-01-01

336

AGRICULTURAL EXPOSURE HISTORY AMONG AFRICAN-AMERICAN FARMERS IN GEORGIA  

Microsoft Academic Search

Agricultural exposures differ across the United States by region, calendar time period, and agricultural practice, but most of the published literature focuses on white men in the Midwest. A pilot study was conducted to explore the breadth and diversity of farming practices over time among African-American farmers in Georgia whose exposures may differ in important ways. Using a comprehensive life

Jane A. Hoppin; J. David Guzman; Paige E. Tolbert; Elaine W. Flagg

2001-01-01

337

Cumulative Estrogen Exposure and Prospective Memory in Older Women  

ERIC Educational Resources Information Center

This study looked at cumulative lifetime estrogen exposure, as estimated with a mathematical index (Index of Cumulative Estrogen Exposure (ICEE)) that included variables (length of time on estrogen therapy, age at menarche and menopause, postmenopausal body mass index, time since menopause, nulliparity and duration of breastfeeding) known to…

Hesson, Jacqueline

2012-01-01

338

Changes in Television and Magazine Exposure and Eating Disorder Symptomatology  

Microsoft Academic Search

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

Kimberley K. Vaughan; Gregory T. Fouts

2003-01-01

339

Solar exposure of LDEF experiment trays  

NASA Technical Reports Server (NTRS)

Exposure to solar radiation is one of the primary causes of degradation of materials on spacecraft. Accurate knowledge of solar exposure is needed to evaluate the performance of materials carried on the Long Duration Exposure Facility (LDEF) during its nearly 6 year orbital flight. Presented here are tables and figures of calculated solar exposure for the experiment rows, longerons, and end bays of the spacecraft as functions of time in orbit. The data covers both direct solar and earth reflected radiation. Results are expressed in cumulative equivalent sun hours (CESH) or the hours of direct, zero incidence solar radiation that would cause the same irradiance of a surface. Space end bays received the most solar radiation, 14,000 CESH; earth end bays received the least, 4,500 CESH. Row locations received between 6,400 CESH and 11,200 CESH with rows facing either eastward or westward receiving the most radiation and rows facing northward or southward receiving the least.

Bourassa, R. J.; Gillis, J. R.

1992-01-01

340

Solar exposure of LDEF experiment trays  

SciTech Connect

Exposure to solar radiation is one of the primary causes of degradation of materials on spacecraft. Accurate knowledge of solar exposure is needed to evaluate the performance of materials carried on the Long Duration Exposure Facility (LDEF) during its nearly 6 year orbital flight. Presented here are tables and figures of calculated solar exposure for the experiment rows, longerons, and end bays of the spacecraft as functions of time in orbit. The data covers both direct solar and earth reflected radiation. Results are expressed in cumulative equivalent sun hours (CESH) or the hours of direct, zero incidence solar radiation that would cause the same irradiance of a surface. Space end bays received the most solar radiation, 14,000 CESH; earth end bays received the least, 4,500 CESH. Row locations received between 6,400 CESH and 11,200 CESH with rows facing either eastward or westward receiving the most radiation and rows facing northward or southward receiving the least.

Bourassa, R.J.; Gillis, J.R.

1992-02-01

341

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

PubMed

Because many occupational epidemiologic studies use exposure surrogates rather than quantitative exposure metrics, the UMass Lowell and Yale study of autobody shop workers provided an opportunity to evaluate the relative utility of surrogates and quantitative exposure metrics in an exposure response analysis of cross-week change in respiratory function. A task-based exposure assessment was used to develop several metrics of inhalation exposure to isocyanates. The metrics included the surrogates, job title, counts of spray painting events during the day, counts of spray and bystander exposure events, and a quantitative exposure metric that incorporated exposure determinant models based on task sampling and a personal workplace protection factor for respirator use, combined with a daily task checklist. The result of the quantitative exposure algorithm was an estimate of the daily time-weighted average respirator-corrected total NCO exposure (microg/m(3)). In general, these four metrics were found to be variable in agreement using measures such as weighted kappa and Spearman correlation. A logistic model for 10% drop in FEV(1) from Monday morning to Thursday morning was used to evaluate the utility of each exposure metric. The quantitative exposure metric was the most favorable, producing the best model fit, as well as the greatest strength and magnitude of association. This finding supports the reports of others that reducing exposure misclassification can improve risk estimates that otherwise would be biased toward the null. Although detailed and quantitative exposure assessment can be more time consuming and costly, it can improve exposure-disease evaluations and is more useful for risk assessment purposes. The task-based exposure modeling method successfully produced estimates of daily time-weighted average exposures in the complex and changing autobody shop work environment. The ambient TWA exposures of all of the office workers and technicians and 57% of the painters were found to be below the current U.K. Health and Safety Executive occupational exposure limit (OEL) for total NCO of 20 microg/m(3). When respirator use was incorporated, all personal daily exposures were below the U.K. OEL. PMID:18615291

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

2008-09-01

342

Exposure Assessment and Modeling of Quartz in Swedish Iron Foundries for a Nested Case-Control Study on Lung Cancer  

Microsoft Academic Search

Exposure assessment of quartz in Swedish iron foundries was performed based on historical and present measurement data. To evaluate the exposure-response relationship between quartz exposure and lung cancer, we modeled quartz exposure from our database of measurements using determinants job title, time period, and company. Based on these modeled exposure data, we conducted a nested case-control evaluation. In our database,

Lena Andersson; Ing-Liss Bryngelsson; Yen Ngo; Carl-Göran Ohlson; Håkan Westberg

2012-01-01

343

Micronuclei and pesticide exposure.  

PubMed

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

Bolognesi, Claudia; Creus, Amadeu; Ostrosky-Wegman, Patricia; Marcos, Ricard

2011-01-01

344

The contributions to solvent uptake by skin and inhalation exposure  

SciTech Connect

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.

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

345

Developing Parameters for Uncommon Exposures  

Microsoft Academic Search

Common exposure scenarios form the basis for exposure assessments included in human health risk assessments. The quantitative parameters that are used to calculate the receptor's dose associated with these common exposure scenarios are readily available. When humans have uncommon exposures, these often are excluded from the dose calculations because of the lack of parameters or parameters are estimated, which can

Michael J. Sullivan

2012-01-01

346

Americans' Average Radiation Exposure  

SciTech Connect

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.

NA

2000-08-11

347

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation  

PubMed Central

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

Kazmi, S. M. Shams; Balial, Satyajit; Dunn, Andrew K.

2014-01-01

348

Occupational exposure to acid mists and periodontal attachment loss.  

PubMed

This study investigated the hypotheses that occupational exposure to acid mists is positively associated with periodontal disease, assessed by periodontal attachment loss. The study sample included 530 male workers at a metal processing factory. Data were obtained from interviews and oral examinations. Periodontal attachment loss was defined as >or= 4mm at probing, in at least one tooth. A job exposure matrix was utilized for exposure evaluation. Exposure to acid mists was positively associated with periodontal attachment loss >or= 4mm at any time (prevalence ratio, PR(adjusted) = 2.17), past (PR(adjusted) = 2.11), and over 6 years of exposure (PR(adjusted) = 1.77), independently of age, alcohol consumption, and smoking, and these results were limited to workers who did not use dental floss. Exposure to acid mists is a potential risk factor for periodontal attachment loss, and further studies are needed, using longitudinal designs and more accurate exposure measures. PMID:18327437

Almeida, Tatiana F de; Vianna, Maria Isabel P; Santana, Vilma S; Gomes Filho, Isaac S

2008-03-01

349

Ultra-accelerated natural sunlight exposure testing  

DOEpatents

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.

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

350

Allergen exposure and control  

Microsoft Academic Search

Allergens produced by the house dust mites (family Pyroglyphidae) are probably the single most important allergens associated with asthma world wide. If exposure to these allergens in houses could be sufficiently reduced, then asthma symptoms may be markedly reduced and even prevented from being initiated. Only about half of the many attempts to reduce mite allergens in houses have shown

Euan R. Tovey

1992-01-01

351

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...

352

Quantifying traffic exposure.  

PubMed

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

Pratt, Gregory C; Parson, Kris; Shinoda, Naomi; Lindgren, Paula; Dunlap, Sara; Yawn, Barbara; Wollan, Peter; Johnson, Jean

2014-01-01

353

Exposure Assessment Methods  

Cancer.gov

Exposure assessment research in the Applied Research Program concentrates on improving self-reports and objective ascertainment of cancer-relevant health behaviors and analytical procedures for processing reported information. Research areas include diet, physical activity, and cognitive and psychometric research.

354

COMMUTER EXPOSURE MODELING METHODOLOGIES  

EPA Science Inventory

Two methodologies for modeling commuter exposures are proposed: computer-oriented approach and a manual approach. Both modeling methodologies require that major commuter routes, or pathways, be identified and that the traffic on the remainder of the roadway network be treated as ...

355

Chemical pneumonitis due to exposure to bromine compounds  

SciTech Connect

A 60-year-old laboratory technician developed pulmonary infiltrates consistent with chemical pneumonitis following accidental exposure to a mixture of hydrogen bromide and phosphorus tribromide. A protracted clinical course ensued consistent with bronchiolitis obliterans. These problems may have been avoided if the potential for subsequent damage had been realized at the time of the initial exposure. Health personnel must be aware of the potentially delayed effects of accidental exposures to respiratory irritants.

Kraut, A.; Lilis, R.

1988-07-01

356

Exposure to inhaled THM: comparison of continuous and event-specific exposure assessment for epidemiologic purposes.  

PubMed

Trihalomethanes (THMs) (chloroform, bromoform, dibromochloromethane, and bromodichloromethane) are the most abundant by-products of chlorination. People are exposed to THMs through ingestion, dermal contact and inhalation. The objective of this study was to compare two methods for assessing THM inhalation: a direct method with personal monitors assessing continuous exposure and an indirect one with microenvironmental sampling and collection of time-activity data during the main event exposures: bathing, showering and swimming. This comparison was conducted to help plan a future epidemiologic study of the effects of THMs on the upper airways of children. 30 children aged from 4 to 10 years were included. They wore a 3M 3520 organic vapor monitor for 7 days. We sampled air in their bathrooms (during baths or showers) and in the indoor swimming pools they visited and recorded their time-activity patterns. We used stainless steel tubes full of Tenax to collect air samples. All analyses were performed with Gas Chromatography and Mass Spectrometry (GC-MS). Chloroform was the THM with the highest concentrations in the air of both bathrooms and indoor swimming pools. Its continuous and event exposure measurements were significantly correlated (r(s)=0.69 p<0.001). Continuous exposures were higher than event exposures, suggesting that the event exposure method does not take into account some influential microenvironments. In an epidemiologic study, this might lead to random exposure misclassification, thus underestimation of the risk, and reduced statistical power. The continuous exposure method was difficult to implement because of its poor acceptability and the fragility of the personal monitors. These two points may also reduce the statistical power of an epidemiologic study. It would be useful to test the advantages and disadvantages of a second sample in the home or of modeling the baseline concentration of THM in the home to improve the event exposure method. PMID:19576633

Thiriat, N; Paulus, H; Le Bot, B; Glorennec, P

2009-10-01

357

Exposure Assessment in Cohort Studies of Childhood Asthma  

PubMed Central

Background The environment is suspected to play an important role in the development of childhood asthma. Cohort studies are a powerful observational design for studying exposure–response relationships, but their power depends in part upon the accuracy of the exposure assessment. Objective The purpose of this paper is to summarize and discuss issues that make accurate exposure assessment a challenge and to suggest strategies for improving exposure assessment in longitudinal cohort studies of childhood asthma and allergies. Data synthesis Exposures of interest need to be prioritized, because a single study cannot measure all potentially relevant exposures. Hypotheses need to be based on proposed mechanisms, critical time windows for effects, prior knowledge of physical, physiologic, and immunologic development, as well as genetic pathways potentially influenced by the exposures. Modifiable exposures are most important from the public health perspective. Given the interest in evaluating gene–environment interactions, large cohort sizes are required, and planning for data pooling across independent studies is critical. Collection of additional samples, possibly through subject participation, will permit secondary analyses. Models combining air quality, environmental, and dose data provide exposure estimates across large cohorts but can still be improved. Conclusions Exposure is best characterized through a combination of information sources. Improving exposure assessment is critical for reducing measurement error and increasing power, which increase confidence in characterization of children at risk, leading to improved health outcomes. PMID:21081299

Arrandale, Victoria H.; Brauer, Michael; Brook, Jeffrey R.; Brunekreef, Bert; Gold, Diane R.; London, Stephanie J.; Miller, J. David; Özkaynak, Halûk; Ries, Nola M.; Sears, Malcolm R.; Silverman, Frances S.; Takaro, Tim K.

2011-01-01

358

Differential exposure to carbon monoxide among sociodemographic groups in Washington, D. C  

SciTech Connect

This study examines the premise that differences in daily activities and residential-location patterns of population subgroups, defined by such personal characteristics as sex, work status, age, and income, lead to differences in exposure to air pollutants. The analysis involved comparing measures of time use, exposure levels, time-space sources of exposure, and CO concentrations among nonworking men, nonworking women, men working in low-exposure jobs, women working in low-exposure jobs, and those working in high-exposure jobs. The focus then turned to patterns of individual-level measures of CO exposure vis-a-vis residential location. Results show: (1) working men have the highest exposures, whereas nonworking women have the lowest exposures; (2) the home is important time/space source of exposure for all groups; (3) variations in the amount of time individuals spend at home and traveling account for very little of the person-to-person variation in total exposure; (4) 70 to 90 % of the interperson variation in exposure is explained by variations in CO concentrations associated with home, work, and travel activities; (5) sampled individuals living in the District of Columbia, Alexandria, and Arlington have higher exposures than do those living in the suburban parts of the Washington, DC SMSA. For the first time, the existence of differential exposure to air pollution among social groups is demonstrated.

Schwab, M.

1988-01-01

359

The Reliability and Stability of Television Exposure  

Microsoft Academic Search

A study was conducted to assess the reliability and stability of television exposure, and the relationship of various demographic variables to this, presumed hypothetical construct, when measurement error is removed. A secondary analysis of survey data collected from a sample of black adults over two points in time served as the basis for this investigation. Using a LISREL model. the

Richard L. Allen

1981-01-01

360

EXPOSURE OF CHILDREN TO INDOOR MOLDS  

EPA Science Inventory

Children now spend more than 90% of their time indoors. Thus, any exposure to indoor pollutants may be critical to their health. Molds are one of the most important pollutants children are exposed to indoors. Molds produce hundreds of allergens and toxins. These products ha...

361

Time Dependence Time Dependence  

E-print Network

Time Dependence 1/60 #12;Time Dependence deadline:= t + 5 2/60 #12;Time Dependence deadline:= t + 5 no problem 3/60 #12;Time Dependence deadline:= t + 5 no problem if t ;Time Dependence deadline:= t + 5 no problem if t Time

Hehner, Eric C.R.

362

Activity Factors of the Korean Exposure Factors Handbook  

PubMed Central

Exposure factors based on the Korean population are required for making appropriate risk assessment. It is expected that handbooks for exposure factors will be applied in many fields, as well as by health department risk assessors. The present article describes the development of an exposure factors handbook that specifically focuses on human activities in situations involving the possible risk of exposure to environmental contaminants. We define majour exposure factors that represent behavioral patterns for risk assessment, including time spent on routine activities, in different places, on using transportation, and engaged in activities related to water contact including swimming, bathing and washing. Duration of residence and employment are also defined. National survey data were used to identify recommended levels of exposure factors in terms of time spent on routine activities and period of residence and employment. An online survey was conducted with 2073 subjects who were selected using a stratified random sampling method in order to develop a list of exposure factors for the time spent in different places and in performing water-related activities. We provide the statistical distribution of the variables, and report reference levels of average exposure based on the reliable data in our exposure factors handbook. PMID:24570804

Jo, Soo-Nam; Kim, So-Yeon; Lee, Kyung-Eun; Choi, Kyung-Ho; Kim, Young-Hee

2014-01-01

363

Health impact assessment of air pollution using a dynamic exposure profile: Implications for exposure and health impact estimates  

SciTech Connect

In both ambient air pollution epidemiology and health impact assessment an accurate assessment of the population exposure is crucial. Although considerable advances have been made in assessing human exposure outdoors, the assessments often do not consider the impact of individual travel behavior on such exposures. Population-based exposures to NO{sub 2} and O{sub 3} using only home addresses were compared with models that integrate all time-activity patterns-including time in commute-for Flanders and Brussels. The exposure estimates were used to estimate the air pollution impact on years of life lost due to respiratory mortality. Health impact of NO{sub 2} using an exposure that integrates time-activity information was on average 1.2% higher than when assuming that people are always at their home address. For ozone the overall estimated health impact was 0.8% lower. Local differences could be much larger, with estimates that differ up to 12% from the exposure using residential addresses only. Depending on age and gender, deviations from the population average were seen. Our results showed modest differences on a regional level. At the local level, however, time-activity patterns indicated larger differences in exposure and health impact estimates, mainly for people living in more rural areas. These results suggest that for local analyses the dynamic approach can contribute to an improved assessment of the health impact of various types of pollution and to the understanding of exposure differences between population groups. - Highlights: Black-Right-Pointing-Pointer Exposure to ambient air pollution was assessed integrating population mobility. Black-Right-Pointing-Pointer This dynamic exposure was integrated into a health impact assessment. Black-Right-Pointing-Pointer Differences between the dynamic and residential exposure were quantified. Black-Right-Pointing-Pointer Modest differences in health impact were found at a regional level. Black-Right-Pointing-Pointer At municipal level larger differences were found, influenced by gender and age.

Dhondt, Stijn, E-mail: stijn.dhondt@vub.ac.be [Department of Medical Sociology and Health Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090, Brussels (Belgium); Beckx, Carolien, E-mail: Carolien.Beckx@vito.be [Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Degraeuwe, Bart, E-mail: Bart.Degraeuwe@vito.be [Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Lefebvre, Wouter, E-mail: Wouter.Lefebvre@vito.be [Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Kochan, Bruno, E-mail: Bruno.Kochan@uhasselt.be [Transportation Research Institute, Hasselt University, Wetenschapspark 5 bus 6, 3590 Diepenbeek (Belgium); Bellemans, Tom, E-mail: Tom.Bellemans@uhasselt.be [Transportation Research Institute, Hasselt University, Wetenschapspark 5 bus 6, 3590 Diepenbeek (Belgium); Int Panis, Luc, E-mail: Luc.intpanis@vito.be [Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Transportation Research Institute, Hasselt University, Wetenschapspark 5 bus 6, 3590 Diepenbeek (Belgium); Macharis, Cathy, E-mail: cjmachar@vub.ac.be [Department MOSI-Transport and Logistics, Vrije Universiteit Brussel, Pleinlaan 2, B-1050, Brussels (Belgium); Putman, Koen, E-mail: kputman@vub.ac.be [Department of Medical Sociology and Health Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090, Brussels (Belgium); Interuniversity Centre for Health Economics Research (I-CHER), Vrije Universiteit Brussel, Brussels (Belgium)

2012-09-15

364

Transient Response of Cadmium Telluride Modules to Light Exposure: Preprint  

SciTech Connect

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.

Deline, C.; del Cueto, J.; Albin, D. S.; Petersen, C.; Tyler, L.; TamizhMani, G.

2011-07-01

365

Étude de dosimétrie en radiologie interventionnelle et radiodiagnostic  

Microsoft Academic Search

The goal of the study made at Troyes Hospital was to estimate the occupational dose for the staff during procedures using X-rays, and thus to optimize their protection. The choice of the medical procedures to be studied has been done on two criteria : the duration of use of X-rays and the occurrence frequency of this type of acts. The

S Laurent-Finta; C Demaire; V Le Lann

2001-01-01

366

Human exposure to nickel.  

PubMed

In order of abundance in the earth's crust, nickel ranks as the 24th element and has been detected in different media in all parts of the biosphere. Thus, humans are constantly exposed to this ubiquitous element, though in variable amounts. The average natural nickel exposure from food in the past has probably been somewhat, but not much, below current levels. Nickel is a useful metal, particularly in various alloys, in batteries and in nickel-plating. Nickel compounds are used especially as catalysts and pigments. In nickel-producing or nickel-using industries, about 0.2% of the work force may be exposed to considerable amounts of airborne nickel. In addition, nickel release, e.g., into cutting oils, and skin contact with nickel-containing or nickel-plated tools and other items may add to an occupational nickel hazard. Occupational exposures may lead to the retention of 100 micrograms of nickel per day. Environmental nickel levels depend particularly on natural sources, pollution from nickel-manufacturing industries and airborne particles from combustion of fossil fuels. Absorption from atmospheric nickel pollution is of minor concern. Vegetables usually contain more nickel than do other food items; high levels have been found in legumes, spinach, lettuce and nuts. Certain products, such as baking powder and cocoa powder, have been found to contain excessive amounts of nickel, perhaps related to nickel leaching during the manufacturing process. Soft drinking-water and acid beverages may dissolve nickel from pipes and containers. Leaching or corrosion processes may contribute significantly to the oral nickel intake, occasionally up to 1 mg/day. Scattered studies indicate a highly variable dietary intake of nickel, but most averages are about 200-300 micrograms/day. In addition, skin contact to a multitude of metal objects may be of significance to the large number of individuals suffering from contact dermatitis and nickel allergy. Finally, nickel alloys are often used in nails and prostheses for orthopaedic surgery, and various sources may contaminate intravenous fluids. Thus, human nickel exposure originates from a variety of sources and is highly variable. Occupational nickel exposure is of major significance, and leaching of nickel may add to dietary intakes and to cutaneous exposures. Preventive efforts should mainly be directed towards adequate control of these exposure sources. PMID:6241927

Grandjean, P

1984-01-01

367

Exposure assessment of diesel bus emissions.  

PubMed

The goal of this study was to measure ultrafine particle concentrations with diameters less than 1 mum emitted by diesel buses and to assess resulting human exposure levels. The study was conducted at the Woolloongabba Busway station in Brisbane, Australia in the winter months of 2002 during which temperature inversions frequently occurred. Most buses that utilize the station are fuelled by diesel, the exhaust of which contains a significant quantity of particle matter. Passengers waiting at the station are exposed to these particles emitted from the buses. During the course of this study, passenger census was conducted, based on video surveillance, yielding person-by-person waiting time data. Furthermore, a bus census revealed accurate information about the total number of diesel versus Compressed Natural Gas (CNG) powered buses. Background (outside of the bus station) and platform measurements of ultrafine particulate number size distributions were made to determine ambient aerosol concentrations. Particle number exposure concentration ranges from 10 and 40 to 60% of bus related exhaust fumes. This changes dramatically when considering the particle mass exposure concentration, where most passengers are exposed to about 50 to 80% of exhaust fumes. The obtained data can be very significant for comparison with similar work of this type because it is shown in previous studies that exhaust emissions causes cancer in laboratory animals. It was assumed that significant differences between platform and background distributions were due to bus emissions which, combined with passenger waiting times, yielded an estimate of passenger exposure to ultrafine particles from diesel buses. From an exposure point of view, the Busway station analyzed resembles a street canyon. Although the detected exhaust particle concentration at the outbound platform is found to be in the picogram range, exposure increases with the time passengers spend on the platform along with their breathing frequency. PMID:17159271

Yip, Maricela; Madl, Pierre; Wiegand, Aaron; Hofmann, Werner

2006-12-01

368

Noise exposure of motorcyclists.  

PubMed

This study was designed to evaluate noise exposure of motorcyclists at work. Open and full face safety helmets were compared and the effects of helmet design and the contribution of radio intercoms investigated. Special measuring equipment is described and hearing protection discussed. Previous studies concentrated mainly on the attenuation of noise by safety helmets, and were made under conditions untypical of day-to-day motorcycling. During town driving the sample equivalent continuous noise level (s.leq) ranged from 63 to 90 dB(A), the intercom giving the highest peak levels. On the open road s.leq was up to 105 dB(A); exposure to this level for only 15 min would exceed the present recommended maximum of 90 dB(A) for an 8 h working day. PMID:2705692

Ross, B C

1989-01-01

369

Exposure Databases and Exposure Surveillance: Promise and Practice  

Microsoft Academic Search

Based on recent developments in occupational health and a review of industry practices, it is argued that integrated exposure database and surveillance systems hold considerable promise for improving workplace health and safety. A foundation from which to build practical and effective exposure surveillance systems is proposed based on the integration of recent developments in electronic exposure databases, the codification of

Anthony D. LaMontagne; Robert F. Herrick; Michael V. Van Dyke; John W. Martyny; A. James Ruttenber

2002-01-01

370

EXPOSURE ASSESSMENT AND FUTURE DIRECTIONS IN EXPOSURE SCIENCE  

EPA Science Inventory

Exposure is the contact between a stressor and a human or ecological receptor. Risk analysis step in which receptor interaction with the exposure stressor of concern is evaluated. To assess exposure to a particular stressor we need to know - Properties of the stressor; Sources, p...

371

Evaluation of retinal exposures from repetitively pulsed and scanning lasers.  

PubMed

Threshold damage in the macaque retina is shown to be equivalent for the argon-krypton (Ar-Kr) 647 nm and the helium-neon (He-Ne) 632.8-nm lines for exposures to continuous wave (CW) radiation from 1 to 1,000 s. This equivalence allows interpolation from experiments with 647-nm, exposures at power levels that are unavailable with the He-Ne laser. To simulate He-Ne laser scanner exposures, 40-microseconds pulses of 647-nm light transmitted through a revolving disk with holes in the periphery were used to expose the retinas of monkeys under deep anesthesia at pulse repetition frequencies (PRFs) of 100, 200, 400, and 1,600 Hz for exposure durations of 1, 10, 100, and 1,000 s. The thresholds between laser exposure at 488 nm (Ar-Kr) and between laser exposure at 647 nm (Kr) are compared to assess thermal versus photochemical effects on the retina. The threshold for 488-nm pulses was consistently lower than that for 647-nm pulses at all PRFs and exposure times. The difference in thresholds increased with exposure time and PRF. The sharp decreases in 488-nm thresholds at 100-s exposure times for each PRF can be interpreted as a basically photochemical effect. The radiant exposure required for damage at 647 nm was several orders of magnitude above the radiant exposure from typical He-Ne scanner applications. From the similarity of the macaque retina to the human retina, it is concluded that no realistic ocular hazard exists from exposure to scanning laser systems of 1 mW or less, operating at higher than 100 Hz. PMID:3346165

Ham, W T; Mueller, H A; Wolbarsht, M L; Sliney, D H

1988-03-01

372

Dangers of Radiation Exposure  

NSDL National Science Digital Library

This is a lesson about radiation and the various sources of radiation that a spacecraft may encounter in its journey. Learners will calculate their annual exposure to high-energy radiation, identify sources of high-energy radiation, and explain why the near-Mercury environment is a concern for the Mercury MESSENGER mission. This is lesson 2 of 4 in the high school track of a module, titled Staying Cool. Note: the student guide starts on p. 17 of the PDF.

373

Identifying Extreme Exposure Values  

Cancer.gov

There are various perspectives on whether to exclude potentially unlikely exposure values. If the researcher chooses to do so, several approaches exist for identifying extreme values. We examined the plausibility of the reported frequencies for each food item in the NHANES 2009-10 DSQ and chose to exclude extreme values using a method that identifies them based on the actual distribution of the sample, but also minimizes the number of values excluded.

374

Partners' influence on each other's television exposure : dominance or symmetry?  

Microsoft Academic Search

Abstract In this study we analyzed to what extent partners who share the same household affect each other's exposure to television. With the use of linear structural equation modeling,we analyzed data from a large scale representative survey in The Netherlands (n 697 couples). Results indicate that both men and women,influence their partner's exposure to television. When people spend much time

Ruben P. Konig; Gerbert Kraaykamp; Henk Westerik

2008-01-01

375

Understanding Greek Primary School Children's Comprehension of Sun Exposure  

Microsoft Academic Search

The purpose of this study was to assess Greek primary (1st to 6th grade) school children's understanding of sun exposure during summer vacation. Our results show that children know the damaging effects of long time exposure and the precautions that should be taken during sun bathing (sun glasses, hat, umbrella, sunscreen, etc). Nevertheless, they do not seem to avoid being

Stylianos M. Piperakis; Vasiliki Papadimitriou; Michael M. Piperakis; Panagiotis Zisis

2003-01-01

376

A controlled trial of cue exposure treatment in alcohol dependence  

Microsoft Academic Search

The clinical effectiveness of cue exposure (CE) treatment in alcohol dependence was evaluated in a controlled trial. Thirty-five men who were detoxified and severely alcohol dependent received either CE or relaxation control (RC) treatment. CE Ss had 400 min exposure to the sight and smell of preferred drinks over 10 days in a laboratory setting. RC Ss spent identical time

D. Colin Drummond; Steven Glautier

1994-01-01

377

Electrothermal controlled-exposure technology  

E-print Network

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 ...

Maloney, John Mapes

2006-01-01

378

Additional exposures reverse the latent inhibitory effects of recent and remote exposures.  

PubMed

We studied the learning produced by simple exposures to a stimulus. Exposures depressed orienting and subsequent conditioned freezing in rats. A remotely preexposed conditioned stimulus (CS) conditioned better and overshadowed a novel CS more than a recently preexposed CS. Additional preexposures reversed these effects: a remotely preexposed CS elicited more orienting, conditioned worse and overshadowed less than a recently preexposed CS. Exposure to a compound composed of a novel CS and a remotely preexposed CS resulted in the novel CS subsequently conditioning better than a novel CS exposed in compound with a recently preexposed CS. The results were interpreted to mean that stimulus-alone exposures produce a loss in associability which recovers across time, that this restoration deepens the loss in associability, and that this deepening is regulated by a common error term. PMID:20658867

Holtzman, Orit; Siette, Joyce; Holmes, Nathan M; Westbrook, R Frederick

2010-07-01

379

Characterization of Firefighter Smoke Exposure  

Microsoft Academic Search

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

Thomas Z. Fabian; Jacob L. Borgerson; Pravinray D. Gandhi; C. Stuart Baxter; Clara Sue Ross; James E. Lockey; James M. Dalton

380

Systematically Controlling for the Influence of Age, Sex, Hertz and Time Post-Whole-Body Vibration Exposure on Four Measures of Physical Performance in Community-Dwelling Older Adults: A Randomized Cross-Over Study  

PubMed Central

Though popular, there is little agreement on what whole-body vibration (WBV) parameters will optimize performance. This study aimed to clarify the effects of age, sex, hertz and time on four physical function indicators in community-dwelling older adults (N = 32). Participants were exposed to 2?min WBV per session at either 2?Hz or 26?Hz and outcome measures were recorded at 2, 20 and 40?min post-WBV. Timed get up-and-go and chair sit-and-reach performances improved post-WBV for both sexes, were significantly different between 2?Hz and 26?Hz treatments (P ? 0.05) and showed statistically significant interactions between age and gender (P ? 0.01). Counter movement jump and timed one-legged stance performances showed a similar but non-significant response to 2?Hz and 26?Hz treatments, though male subjects showed a distinct trended response. Age and gender should be statistically controlled and both 2?Hz and 26?Hz exert a treatment effect. PMID:21977028

Merriman, Harold L.; Brahler, C. Jayne; Jackson, Kurt

2011-01-01

381

Comparison of modeling approaches to prioritize chemicals based on estimates of exposure and exposure potential  

PubMed Central

While only limited data are available to characterize the potential toxicity of over 8 million commercially available chemical substances, there is even less information available on the exposure and use-scenarios that are required to link potential toxicity to human and ecological health outcomes. Recent improvements and advances such as high throughput data gathering, high performance computational capabilities, and predictive chemical inherency methodology make this an opportune time to develop an exposure-based prioritization approach that can systematically utilize and link the asymmetrical bodies of knowledge for hazard and exposure. In response to the US EPA’s need to develop novel approaches and tools for rapidly prioritizing chemicals, a “Challenge” was issued to several exposure model developers to aid the understanding of current systems in a broader sense and to assist the US EPA’s effort to develop an approach comparable to other international efforts. A common set of chemicals were prioritized under each current approach. The results are presented herein along with a comparative analysis of the rankings of the chemicals based on metrics of exposure potential or actual exposure estimates. The analysis illustrates the similarities and differences across the domains of information incorporated in each modeling approach. The overall findings indicate a need to reconcile exposures from diffuse, indirect sources (far-field) with exposures from directly, applied chemicals in consumer products or resulting from the presence of a chemical in a microenvironment like a home or vehicle. Additionally, the exposure scenario, including the mode of entry into the environment (i.e. through air, water or sediment) appears to be an important determinant of the level of agreement between modeling approaches. PMID:23707726

Mitchell, Jade; Arnot, Jon A.; Jolliet, Olivier; Georgopoulos, Panos G.; Isukapalli, Sastry; Dasgupta, Surajit; Pandian, Muhilan; Wambaugh, John; Egeghy, Peter; Cohen Hubal, Elaine A.; Vallero, Daniel A.

2014-01-01

382

Comparison of modeling approaches to prioritize chemicals based on estimates of exposure and exposure potential.  

PubMed

While only limited data are available to characterize the potential toxicity of over 8 million commercially available chemical substances, there is even less information available on the exposure and use-scenarios that are required to link potential toxicity to human and ecological health outcomes. Recent improvements and advances such as high throughput data gathering, high performance computational capabilities, and predictive chemical inherency methodology make this an opportune time to develop an exposure-based prioritization approach that can systematically utilize and link the asymmetrical bodies of knowledge for hazard and exposure. In response to the US EPA's need to develop novel approaches and tools for rapidly prioritizing chemicals, a "Challenge" was issued to several exposure model developers to aid the understanding of current systems in a broader sense and to assist the US EPA's effort to develop an approach comparable to other international efforts. A common set of chemicals were prioritized under each current approach. The results are presented herein along with a comparative analysis of the rankings of the chemicals based on metrics of exposure potential or actual exposure estimates. The analysis illustrates the similarities and differences across the domains of information incorporated in each modeling approach. The overall findings indicate a need to reconcile exposures from diffuse, indirect sources (far-field) with exposures from directly, applied chemicals in consumer products or resulting from the presence of a chemical in a microenvironment like a home or vehicle. Additionally, the exposure scenario, including the mode of entry into the environment (i.e. through air, water or sediment) appears to be an important determinant of the level of agreement between modeling approaches. PMID:23707726

Mitchell, Jade; Arnot, Jon A; Jolliet, Olivier; Georgopoulos, Panos G; Isukapalli, Sastry; Dasgupta, Surajit; Pandian, Muhilan; Wambaugh, John; Egeghy, Peter; Cohen Hubal, Elaine A; Vallero, Daniel A

2013-08-01

383

USING REGIONAL EXPOSURE CRITERIA AND UPSTREAM REFERENCE DATA TO CHARACTERIZE SPATIAL AND TEMPORAL EXPOSURES TO CHEMICAL CONTAMINANTS  

EPA Science Inventory

Analyses of biomarkers in fish were used to evaluate exposures among locations and across time. Two types of references were used for comparison, an upstream reference sample remote from known point sources and regional exposure criteria derived from a baseline of fish from refer...

384

USING REGIONAL EXPOSURE CRITERIA AND UPSTREAM REFERENCE DATA TO CHARACTERIZE SPATIAL AND TEMPORAL EXPOSURES TO CHEMICAL CONTAMINANTS  

EPA Science Inventory

Analyses of biomarkers in fish were used to evaluate exposures among locations and across time. Two types of references were used for comparison, an upstream reference sample remote from known point sources and regional exposure criteria derived from a basline of fish from refere...

385

EXPOSURE FACTORS HANDBOOK PROJECT OVERVIEW  

EPA Science Inventory

The Exposure Factors Handbook (EPA/600/P-95/002Fa-Fc) was published in August 1997. The Handbook provides summary statistical data on exposure factors necessary to assess human exposures to environmental contaminants. New data and studies have become available since 1997. The ...

386

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...

387

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...

388

Noise exposure reconstruction and evaluation of exposure trends in two large automotive plants.  

PubMed

This study used a task-based approach to reconstruct employee noise exposures at two large automotive manufacturing plants for the period 1970-1989, utilizing historic noise measurement data, work history records, documented changes in plant operations, focus group discussions, structured interviews with long-tenure employees, and task-based job profiles. Task-based job noise exposure profiles were developed in the 1990s when the plants conducted task-based noise monitoring. Under the assumption that tasks and time-at-task profile within jobs did not change over time, these profiles were applied to historic jobs. By linking historic noise exposure measurements to job tasks, this approach allowed task-based reconstructed noise exposure profiles to capture variability of daily noise exposures. Reconstructed noise exposures, along with task-based noise exposure measurements collected at each plant during the 1990s, were analyzed to examine time trends in workplace noise levels and worker noise exposure. Our analysis of noise exposure trends revealed that noise levels for many jobs declined by ?3 dBA from 1970 to 1998 as operational and equipment changes occurred in the plants and some noise control measures were implemented, but for some jobs, noise levels increased in the mid- to late 1990s, most likely because of an increase in production at that time. Overall, the percentage of workers exposed to noise levels >90 dBA decreased from 95% in 1970 to 54% in 1998 at one of the plants and decreased from 36% in 1970 to ~5% in 1999 at the other plant. These reductions indicate a degree of success for the hearing conservation program. However, the actual number of employees with noise exposure >90 dBA increased because of a substantial increase in the number of production employees, particularly in jobs with high noise levels, which shows a hearing conservation program challenge that companies face during periods of increased production. Future analysis of hearing levels in these plant populations will help determine whether noise level reduction translates into decreased hearing loss at these plants. PMID:23852046

Brueck, Scott E; Prince Panaccio, Mary; Stancescu, Daniel; Woskie, Susan; Estill, Cheryl; Waters, Martha

2013-11-01

389

Residual neurobehavioural effects associated with chronic exposure to mercury vapour.  

PubMed Central

To find the residual effects of long term exposure to mercury vapour, neurobehavioural tests were given to ex-mercury miners about 18 years after the end of mercury exposure. Seventy six male ex-mercury miners who had been exposed to high concentrations of mercury vapour (over 1.0 mg/m3) and with a history of mercury intoxication were compared with controls matched for age (within 3 years), sex, and education. Although the extent of the workers' symptoms caused by mercury poisoning, termed erethismus merculialis, decreased considerably after the end of exposure, matched paired comparison showed that performances of motor coordination, simple reaction time, and short term memory had deteriorated significantly in the exposed group. Multiple linear regression analysis of exposure variables with neurological examination measures showed positive correlations between poorer neurological performance and variables related to mercury exposure. Thus the duration of exposure correlated with poorer performance of hand-eye coordination, tapping, and a colour card reading test. Job categories classified by exposure to mercury also had a significant negative correlation with these performances. The period of years after the end of exposure had a significant correlation with better performance of reaction time and digit span. On the other hand, the history of intoxication itself had no significant correlation with any of the current neurobehavioural performances. These results suggest that there are slight but persistent effects on neurobehavioural function, especially on motor coordination, among mercury miners even more than 10 years after the end of exposure. PMID:8124461

Kishi, R; Doi, R; Fukuchi, Y; Satoh, H; Satoh, T; Ono, A; Moriwaka, F; Tashiro, K; Takahata, N; Sasatani, H

1994-01-01

390

Real exposure: field measurement of chemical plumes in headwater streams.  

PubMed

In fluvial systems, organismic exposure to nonpoint source pollutants will fluctuate in frequency (exposure events), intensity (concentration), and duration. The reliance on lethal concentrations and static exposure in many laboratory studies does not adequately represent nor address exposure to in situ chemical plumes of fluvial habitats. To adequately address field exposure in a laboratory setting, one needs an understanding of the physics of chemical transmission within moving fluids. Because of the chaotic nature of turbulence, chemical plumes introduced to fluvial systems have a spatial and temporal microstructure with fluxes in chemical concentration. Consequently, time-averaged static exposure models are not ecologically relevant for the major reason of in situ distribution. The purpose of this study was to quantify in situ chemical distribution and dispersion within two physically different streams. Dopamine was introduced as a chemical tracer mimicking groundwater runoff. Chemical fluxes and stream hydrodynamics were simultaneously measured using a microelectrode and an acoustic Doppler velocimeter, respectively, at three heights of three downstream locations at each research site. Fine-scale measurements of the dopamine plume microstructure showed that organisms could be exposed to chemical fluctuations where concentrations are significantly greater than the overall time-averaged concentration. These measurements demonstrate that rather than relying on static exposure, standards for pollution must consider the concept of exposure being interdependently linked to flow of the fluid medium. The relationship between fluid dynamics, pollution exposure, and organism physiology are complex and must be evaluated in ways to mimic natural systems. PMID:24950614

Edwards, David D; Moore, Paul A

2014-10-01

391

Urinary biomarkers of exposure to jet fuel (JP-8).  

PubMed Central

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

Serdar, Berrin; Egeghy, Peter P; Waidyanatha, Suramya; Gibson, Roger; Rappaport, Stephen M

2003-01-01

392

Cases of mercury exposure, bioavailability, and absorption.  

PubMed

Mercury is a unique element that, unlike many metals, has no essential biological function. It is liquid at room temperature and is 13.6 times heavier than water. Its unique physical properties have been exploited for a variety of uses such as in mercury switches, thermostats, thermometers, and other instruments. Its ability to amalgamate with gold and silver are used in mining these precious metals and as a dental restorative. Its toxic properties have been exploited for medications, preservatives, antiseptics, and pesticides. For these reasons there have been many industrial uses of mercury, and occupational exposures of workers and industrial emissions and effluents contaminating air, water, soil, and ultimately food chains have long been a matter of great public health concern. This paper examines briefly six cases representing various forms of exposure to different species of mercury, and indicates the methodological issues in estimating exposure, bioavailability and absorption; these cases include Minamata disease in Japan, organic mercury poisoning in Iraq, methylmercury (MeHg) exposure in the Amazon, dimethylmercury (PMM) in the laboratory, an elemental mercury spill in Cajamarca, Peru, and a mercury-contaminated building in Hoboken, NJ, USA. Other scenarios that are not described include occupational exposure to mercury salts, mercurial preservatives in vaccines, cultural and ritualistic uses of mercury, and mercury in dental amalgams. PMID:12915150

Gochfeld, Michael

2003-09-01

393

Human biomonitoring issues related to lead exposure.  

PubMed

Lead as a toxic environmental metal has been an issue of concern for 30-40 years. Even though the exposures experienced by the general public have been significantly reduced, so have the acceptable blood lead concentrations assessed to safeguard health (specifically of children). The impact of these concurrent changes are reviewed and discussed in terms of the following: blood lead as the primary biomarker of exposure; pertinent toxicokinetic issues including modelling; legacy and newer sources of this toxic metal; improvements in lead quantification techniques and its characterization (chemical forms) in exposure media; and in vivo markers of lead sources. It is concluded that the progress in the quantification of lead and its characterization in exposure media have supported the efforts to identify statistical associations of lead in blood and tissues with adverse health outcomes, and have guided strategies to reduce human exposure (especially for children). To clarify the role of lead as a causative factor in disease, greater research efforts in biomarkers of effect and susceptibility seem timely. PMID:23970117

Nieboer, Evert; Tsuji, Leonard J S; Martin, Ian D; Liberda, Eric N

2013-10-01

394

Adenocarcinoma of the stomach and exposure to occupational dust  

SciTech Connect

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.

Wright, W.E.; Bernstein, L.; Peters, J.M.; Garabrant, D.H.; Mack, T.M.

1988-07-01

395

Exposure to particles from laser printers operating within office workplaces.  

PubMed

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