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Laumbach R.J.,Environmental and Occupational Health science Institute
American Family Physician | Year: 2010

Almost 160 million persons live in areas of the United States that exceed federal health-based air pollution standards. The two air pollutants that most commonly exceed standards are ozone and particulate matter. Ozone and particulate matter can harm anyone if levels are sufficiently elevated, but health risk from air pollution is greatest among vulnerable populations. Both ozone and particulate matter can cause pulmonary inflammation, decreased lung function, and exacerbation of asthma and chronic obstructive pulmonary disease. Particulate matter is also strongly associated with increased cardiovascular morbidity and mortality. Children, older adults, and other vulnerable persons may be sensitive to lower levels of air pollution. Persons who are aware of local air pollution levels, reported daily by the U.S. Environmental Protection Agency as the Air Quality Index, can take action to reduce exposure. These actions include simple measures to limit exertion and time spent outdoors when air pollution levels are highest, and to reduce the infiltration of outdoor air pollutants into indoor spaces. Copyright © 2010 American Academy of Family Physicians. Source

Xue J.,U.S. Environmental Protection Agency | Zartarian V.,U.S. Environmental Protection Agency | Wang S.-W.,National Taiwan University | Liu S.V.,U.S. Environmental Protection Agency | Georgopoulos P.,Environmental and Occupational Health science Institute
Environmental Health Perspectives | Year: 2010

BACKGROUND: Dietary exposure from food to toxic inorganic arsenic (iAs) in the general U.S. population has not been well studied. OBJECTIVES: The goal of this research was to quantify dietary As exposure and analyze the major contributors to total As (tAs) and iAs. Another objective was to compare model predictions with observed data. METHODS: Probabilistic exposure modeling for dietary As was conducted with the Stochastic Human Exposure and Dose Simulation-Dietary (SHEDS-Dietary) model, based on data from the National Health and Nutrition Examination Survey. The dose modeling was conducted by combining the SHEDS-Dietary model with the MENTOR-3P (Modeling ENvironment for TOtal Risk with Physiologically Based Pharmacokinetic Modeling for Populations) system. Model evaluation was conducted via comparing exposure and dose-modeling predictions against duplicate diet data and biomarker measurements, respectively, for the same individuals. RESULTS: The mean modeled tAs exposure from food is 0.38 μg/kg/day, which is approximately 14 times higher than the mean As exposures from the drinking water. The mean iAs exposure from food is 0.05 μg/kg/day (1.96 μg/day), which is approximately two times higher than the mean iAs exposures from the drinking water. The modeled exposure and dose estimates matched well with the duplicate diet data and measured As biomarkers. The major food contributors to iAs exposure were the following: vegetables (24%); fruit juices and fruits (18%); rice (17%); beer and wine (12%); and flour, corn, and wheat (11%). Approximately 10% of tAs exposure from foods is the toxic iAs form. CONCLUSIONS: The general U.S. population may be exposed to tAs and iAs more from eating some foods than from drinking water. In addition, this model evaluation effort provides more confidence in the exposure assessment tools used. Source

Gochfeld M.,Rutgers University | Gochfeld M.,Environmental and Occupational Health science Institute | Burger J.,The New School
American Journal of Public Health | Year: 2011

We examined traditional environmental justice populations and other groups whose exposure to contaminants is often disproportionately high. Risk assessment methods may not identify these populations, particularly if they are spatially dispersed. We suggest using a National Health and Nutrition Examination Survey approach to oversample minority communities and develop methods for assessing exposure at different distances from pollution sources; publishing arithmetic and geometric means and full distributions for minority populations; and paying particular attention to high-end exposures. Means may sufficiently characterize populations as a whole but are inadequate in identifying vulnerable groups and subgroups. The number of individuals above the 95th percentile of any distribution may be small and unrepresentative, but these outliers are the ones who need to be protected. Source

Richmond-Bryant J.,U.S. Environmental Protection Agency | Isukapalli S.S.,Environmental and Occupational Health science Institute | Vallero D.A.,U.S. Environmental Protection Agency
Atmospheric Environment | Year: 2011

Epidemiological studies of health effects associated with ambient air pollution are subject to uncertainty in the effects estimates related to the spatial and temporal variability of ambient air pollution. This study examines meteorological and concentration decay data for an urban canopy in Oklahoma City, OK to develop a modeling approach that can be used to estimate spatiotemporal variability in contaminant retention that could add bias or uncertainty to epidemiological results. Concentration and microscale turbulent wind data from the Joint Urban 2003 study were reanalyzed to examine scaling relationships between contaminant residence time in urban street canyons, urban boundary layer winds, and urban topography. Street-level sulfur hexafluoride (SF 6) concentration time series were reviewed to find time periods that included a peak and decay. Exponential decay curves were fitted to each period, and a characteristic residence time was derived from each model slope. That residence time was nondimensionalized by the ratio of mean urban boundary layer wind speed to height of the building just upwind of the street canyon in which the concentration was measured. Sonic detection and ranging (SODAR) data were used to assess atmospheric turbulence conditions at times concurrent with the concentration decay measurements. Reynolds number (Re) was calculated from the 15-min average wind velocity and ranged from 2.1 × 10 6 to 7.6 × 10 7. Nondimensional residence time (H) ranged from 3.7 to 996 with a median of 13.3. Inverse relationships were validated between H and Re and between H and the street canyon aspect ratio. These relationships provided a mechanism to understand time-varying ventilation within a street canyon. The results shown here were intended to demonstrate how scaling relationships derived from the transport equation can be used to provide rapid estimates of characteristic decay times for the purpose of estimating variability in the concentrations encountered in an urban environment. This could be a useful tool to reduce uncertainty in air pollution epidemiological study results related to spatial and temporal variability in urban concentrations. Source

Weisel C.P.,Environmental and Occupational Health science Institute
Chemico-Biological Interactions | Year: 2010

Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures. Inhalation is the most common exposure route but benzene rapidly penetrates the skin and can contaminant water and food resulting in dermal and ingestion exposures. While less toxic solvents have been substituted for benzene, it still is a component of petroleum products, including gasoline, and is a trace impurity in industrial products resulting in continued sub to low ppm occupational exposures, though higher exposures exist in small, uncontrolled workshops in developing countries. Emissions from gasoline/petrochemical industry are its main sources to the ambient air, but a person's total inhalation exposure can be elevated from emissions from cigarettes, consumer products and gasoline powered engines/tools stored in garages attached to homes. Air samples are collected in canisters or on adsorbent with subsequent quantification by gas chromatography. Ambient air concentrations vary from sub-ppb range, low ppb, and tens of ppb in rural/suburban, urban, and source impacted areas, respectively. Short-term environmental exposures of ppm occur during vehicle fueling. Indoor air concentrations of tens of ppb occur in microenvironments containing indoor sources. Occupational and environmental exposures have declined where regulations limit benzene in gasoline (<1%) and cigarette smoking has been banned from public and work places. Similar controls should be implemented worldwide to reduce benzene exposure. Biomarkers of benzene used to estimate exposure and risk include: benzene in breath, blood and urine; its urinary metabolites: phenol, t,. t-muconic acid (t,. tMA) and S-phenylmercapturic acid (sPMA); and blood protein adducts. The biomarker studies suggest benzene environmental exposures are in the sub to low ppb range though non-benzene sources for urinary metabolites, differences in metabolic rates compared to occupational or animal doses, and the presence of polymorphisms need to be considered when evaluating risks from environmental exposures to individuals or potentially susceptible populations. © 2010 Elsevier Ireland Ltd. Source

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