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Human Exposure and Atmospheric Sciences Division Publications: 2008

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This page lists publication titles, citations and abstracts produced by NERL's Human Exposure and Atmospheric Sciences Division for the year 2008, organized by Publication Type. Your search has returned 32 Matching Entries.

See also Human Exposure and Atmospheric Sciences Division citations with abstracts: 1999,  2000,  2001,  2002,  2003,  2004,  2005,  2006,  2007,  2008,  2009

Technical Information Manager: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov

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Presented/Published
BOOK CHAPTER The Importance of Exposure in Addressing Current and Emerging Air Quality Issues 08/03/2008
WATKINS, T. H., R. W. WILLIAMS, A. F. VETTE, J. M. BURKE, B. J. GEORGE, AND V. ISAKOV. The Importance of Exposure in Addressing Current and Emerging Air Quality Issues. Chapter 7, Carlos Borrego and Ana Isabel Miranda (ed.), Air Pollution Modeling and Its Application XIX. Springer, New York, NY, 640-647, (2008).
Abstract: The air quality issues that we face today and will face in the future are becoming increasingly more complex and require an improved understanding of human exposure to be effectively addressed. The objectives of this paper are (1) to discuss how concepts of human exposure and exposure science and should be applied to improve air quality management practices and (2) to show how air quality modeling tools can be used to improve exposures estimates used for understanding associations between air quality and human health. Data from a large human exposure monitoring study is presented to demonstrate the value of exposure in understanding important air quality issues, such as health effects associated with exposure to components of particulate matter (PM), to PM of different size fractions (coarse and ultrafine), and to air pollution in near roadway environments. Various approaches for improving estimates of exposure via application of air quality modeling are discussed and results from example modeling applications are presented. These air quality modeling approaches include: the integration of regional scale eulerian air quality models with local scale gaussian dispersion models; the fusion of modeled estimates with air quality observations; the integration of air quality and human exposure modeling tools; and the use of exposure factors, such as housing ventilation, to adjust modeled estimates of ambient air quality.

BOOK CHAPTER Dispersion Modeling in Complex Urban Systems 02/01/2008
VALLERO, D. A., A. H. HUBER, AND P. J. LIOY. Dispersion Modeling in Complex Urban Systems. , 2008., Chapter A-Z, David Blumel, Stefan Malmoli, Jessa Netting (ed.), Yearbook of Science and Technology. McGraw-Hill Companies, New York, NY, 95-101, (2008).
Abstract: Models are used to represent real systems in an understandable way. They take many forms. A conceptual model explains the way a system works. In environmental studies, for example, a conceptual model may delineate all the factors and parameters for determining how a particle moves in the atmosphere after it has been released from a power plant. A conceptual model may also help identify the major influences on where a chemical is emitted and how likely it is to be found in the environment. Such models need to be developed to help target sources of data for assessing environmental problems. In general, developing an air pollution model involves two steps. First, a model of the domain and processes being studied must be defined and mathematical algorithms selected to represent the system. Then, the model boundary conditions are defined to represent the influence of the environment and other factors associated with the study. The quality of the model study is related to the accuracy and representativeness of the actual study.

BOOK CHAPTER Asbestos Measurement 02/01/2008
Kominsky, J., D. A. VALLERO, AND M. E. BEARD. Asbestos Measurement. , 2008., Chapter A-Z, Yearbook of Science & Technology. McGraw-Hill Companies, New York, NY, 2008:20-26, (2008).
Abstract: Environmental engineers are generally concerned with two types of air pollutants, gases and particulate matter (PM). Generally, the mass of PM falling in two size categories is measured, i.e. ≤2.5 µm diameter, and between 2.5 µm and 10 µm diameter. These measurements are taken by instruments (see Fig. 1) with inlets using size exclusion mechanisms to segregate the mass of each size fraction (i.e. “dichotomous” samplers). Particles with diameters ≥10 µm are generally of less concern, since their mass is sufficiently large that they rarely travel long distances. However, they are occasionally measured if a large particulate emitting source (e.g. a coal mine) is nearby.

COMMUNICATION PRODUCT The Detroit Exposure and Aerosol Research Study (Dears) Article in National Ambient Air Quality Status and Trends Through 2007 06/04/2008
WILLIAMS, R. W. The Detroit Exposure and Aerosol Research Study (Dears) Article in National Ambient Air Quality Status and Trends Through 2007. U.S. Environmental Protection Agency, Washington, DC, EPA/600/F-08/008, 2008.
Abstract: A research study that the U.S. Environmental Protection Agency conducted in Detroit, Michigan, named the Detroit Exposure and Aerosol Research Study (DEARS), will help develop data that improves our understanding of human exposure to various air pollutants in our environment.

EPA PUBLISHED PROCEEDINGS Proceedings: Isea Bioavailability Symposium, Durham, North Carolina Use of Invitro Bioaccessibility/Relative Bioavailability Estimates for Metals in Regulatory Settings: What Is Needed? 04/15/2008
BRADHAM, K. D., M. BERINGER, AND A. YEOW. Proceedings: Isea Bioavailability Symposium, Durham, North Carolina Use of Invitro Bioaccessibility/Relative Bioavailability Estimates for Metals in Regulatory Settings: What Is Needed? ISEA Bioavailability Symposium , Durham, NC, October 14 - 18, 2007. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-08/102 (NTIS PB2008-113476), 2008.
Abstract: Oral ingestion of soil and dust is a key pathway for human exposures to metal and metalloid contaminants. It is widely recognized that the site-specific bioavailability of metals in soil and dust may be reduced relative to the metal bioavailability in media such as water and food, and adjustments for oral relative bioavailability are becoming more accepted. Both animal models and in vitro bioaccessibility models have been used to estimate relative bioavailability of metals in soil and dust. Although animal models are often considered the "gold standard", they may be costly or otherwise prohibitive at certain sites and may not be sensitive enough to test environmentally relevant samples for all contaminants. Routine application of in vitro metal bioaccessibility models in regulatory settings is being held up by different perceptions of what is required of these models in terms of validation. This symposium provided the opportunity for international experts to exchange their views on methods for assessing relative bioavailability/bioaccessibility for application in risk assessments at contaminated sites. The symposium speakers presented recent developments in animal models, new in vitro models, the role of mineralogical analyses in assessing relative bioavailability, and the application of physiologically based models as research tools. In addition, two panel discussions addressed specific research questions and discussed future research needs in this area. Recognizing the multi-disciplinary nature of exposure assessment, this symposium included representation from many disciplines including risk assessment, toxicology, environmental geochemistry, geology, soil, and analytical chemistry from the U.S., Europe, and Canada.

JOURNAL Contributions of Diesel Truck Emissions to Indoor Elemental Carbon Concentrations in Home Proximate to Ambassador Bridge 12/15/2008
BAXTER, L. K., T. M. BARZYK, A. F. VETTE, C. W. CROGHAN, AND R. W. WILLIAMS. Contributions of Diesel Truck Emissions to Indoor Elemental Carbon Concentrations in Home Proximate to Ambassador Bridge. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(40):9080-9086, (2008).
Abstract: Ambassador Bridge, connecting Detroit, Michigan and Windsor, Ontario, is the busiest international commercial vehicle crossing in North America, with a large percentage of heavy duty diesel trucks. This study seeks to examine the contribution of diesel truck traffic across Ambassador Bridge to indoor exposure patterns of elemental carbon (EC), a common surrogate for diesel exhaust particles, in homes in close proximity to the bridge. We also aim to understand the relative importance of home ventilation characteristics and wind speed. Measurements were collected as part of the Detroit Exposure and Aerosol Research Study (DEARS). Residential indoor and outdoor EC measurements were collected over five consecutive 24 h periods in both the summer and winter at 16 homes in close proximity to Ambassador Bridge. Ambient concentrations and meteorological data were collected at a central-site monitor, and home air exchange rates were estimated using a perfluorocarbon tracer. The contributions of ambient concentrations and Ambassador Bridge, and potential effect modification by wind speed and home ventilation status were quantified with regression analyses. Both ambient concentrations and the percentage of time a home was downwind from the bridge were associated with an increase in indoor concentrations. Ambient concentrations significantly contributed to indoor concentrations regardless of wind speed category but were a greater influence in home experiencing calm winds. The effect of the percent of time downwind variable on indoor levels was only significant in homes where the ventilation status was high. The distance a home was from the bridge tollbooth complex was not significantly associated with indoor concentrations. We conclude that diesel traffic emissions related to Ambassador Bridge may have an impact on indoor EC exposures. Given that people spend the majority of their time indoors, it is important to evaluate the impact of traffic-related pollution in the home environment.

JOURNAL Identification of Surrogate Measures of Diesel Exhaust Exposure in a Controlled Chamber Study 12/01/2008
SOBUS, J., J. D. PLEIL, M. C. MADDEN, W. E. Funk, H. HUBBARD, AND S. M. Rappaport. Identification of Surrogate Measures of Diesel Exhaust Exposure in a Controlled Chamber Study. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 42(23):8822-8828, (2008).
Abstract: Exposure to diesel exhaust (DE) has been associated with acute cardiopulmonary and vascular responses, chronic noncancer health effects, and respiratory cancers in humans. To better understand DE exposures and eventually their related health effects, we established a controlled chamber experiment wherein human volunteer subjects were exposed to approximately 100 μm3 of DE. In general, human exposure assessment for DE is based on ambient air measurements of surrogates such as elemental carbon (EC) or total organic carbon (OC) collected on filters. As specific health effect mechanisms and dose response are obscured by the complex composition of DE, the linkage from exposure to internal dose can presumably be improved using specific biomarkers and metabolites in blood, breath, or urine. Because EC or OC are not suitable as biomarkers, in this study, we focus on identifying compounds that are demonstrated indicators of DE and can also be found in biological fluids. We measured an assortment of volatile, semi-volatile, and particle-bound aromatic compounds in the chamber air and report their airborne concentrations in DE and purified air, as well as the estimated values of the corresponding exposure ratios (mean DE air concentration: mean purified air concentration). These estimated exposure ratios were used to identify naphthalene (Nap) and phenanthrene (Phe) as potentially useful surrogates for DE exposure that could also serve as biomarkers. Estimated mean levels of Nap and Phe associated with the nominal 100 μg/m3 of DE were 2600 ng/m3 and 765 ng/m3 with estimated exposure ratios of 252 and 92.4, respectively. Nap levels were significantly correlated with OC, and total particle-bound PAHs; Phe levels were significantly correlated with total volatile+semivolatile PAHs. These results suggest that Nap and Phe may be particularly useful surrogates for DE concentrations. While Nap and Phe are not validated here as internal biomarkers of DE exposure, we are currently assessing human biological specimens collected during this study, and will discuss those results in ensuing articles.

JOURNAL Key Scientific and Policy-and Health-Relevant Findings from EPA's Particulate Matter Supersites Program and Related Studies: An Integration and Synthesis of Results. 12/01/2008
SOLOMON, P. A., P. K. HOPKE, J. Foines, AND R. SCHEFFE. Key Scientific and Policy-and Health-Relevant Findings from EPA's Particulate Matter Supersites Program and Related Studies: An Integration and Synthesis of Results. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION. Air & Waste Management Association, Pittsburgh, PA, 58(13):S-1 - S-92, (2008).
Abstract: In 1998, the Environmental Protection Agency (EPA) initiated a major air quality program, known as the Particulate Matter (PM) Supersites Program. The Supersites Program was a multi year, $27 million air quality monitoring program consisting of eight regional air quality projects located throughout the U.S., each with differing atmospheric pollution conditions resulting from variations in source emissions and meteorology. The overall goal of the program was to elucidate source–receptor relationships and atmospheric processes leading to PM accumulation on urban and regional scales, and thus, provide the scientific underpinning for modeling and data analysis efforts to support State Implementation Plans and more effective risk management approaches for PM. The program had three main objectives: 1) conduct methods development and evaluation, 2) characterize ambient PM, and 3) support health effects and exposure research. This paper provides a synthesis of key policy-relevant, scientific findings from the Supersites Program and related studies. EPA developed sixteen science/policy-relevant questions in conjunction with state agencies, Regional Planning Organizations, and the private sector. These questions were addressed to the extent possible, even given the vast amount of new information available from the Supersites Program, in a series of papers published as a special issue of JAWMA (February, 2008). This synthesis also includes discussions of: a) initial Supersites Program support for air quality management efforts in specific locations throughout the U.S.; b) selected policy-relevant insights, based on atmospheric science findings, useful to air quality managers and decision makers planning emissions management strategies to address current and future PM NAAQS and network planning and implementation; c) selected health-relevant findings interpreted from atmospheric sciences findings in light of future directions for health and exposure scientists planning studies of the effects of PM on human health; and d) selected knowledge gaps to guide future research. Finally, given the scope and depth of research and findings from the Supersites Program, this paper provides a reference source so readers can glean a general understanding of the overall research conducted and its policy-relevant findings. Supporting details for the results presented are available through the cited references. An annotated table of contents allows readers to find easily specific subject matter within the text.

JOURNAL Pyrethroid Pesticides and Their Metabolites in Vacuum Cleaner Dust Collected from Homes and Day-Care Centers 11/01/2008
STARR, J. M., S. E. GRAHAM, D. M. STOUT, K. Andrews, AND M. Nishioka. Pyrethroid Pesticides and Their Metabolites in Vacuum Cleaner Dust Collected from Homes and Day-Care Centers. ENVIRONMENTAL RESEARCH. Elsevier Science Ltd, New York, NY, 108(3):271-279, (2008).
Abstract: The purpose of this study was to quantify the concentrations of 13 selected pyrethroid pesticides and their degradation products in samples of indoor dust that had been collected in vacuum cleaner bags during the Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants (CTEPP) study, of homes and day cares in North Carolina and Ohio.

JOURNAL Isea 2007 Panel: Integration of Better Exposure Characterizations Into Disaster Preparedness for Responders and the Public 11/01/2008
RODES, C. E., E. D. PELLIZZARI, M. J. DELLARCO, M. D. Erickson, D. A. VALLERO, D. B. Reissman, P. J. LIOY, M. LIPPMANN, T. A. Burke, AND B. D. Goldstein. Isea 2007 Panel: Integration of Better Exposure Characterizations Into Disaster Preparedness for Responders and the Public. Journal of Exposure Science and Environmental Epidemiology . Nature Publishing Group, London, Uk, 18(6):541-550, (2008).
Abstract: An expert panel was convened in October 2007 at the International Society for Exposure Analysis (ISEA) Annual Meeting in Durham, NC, entitled “The Path Forward in Disaster Preparedness Since WTC—Exposure Characterization and Mitigation: Substantial Unfinished Business!” The panel prospectively discussed the critical exposure issues being overlooked during disaster responses and highlighted the needs for an optimal blending of exposure characterizations and hazard controls within disaster settings. The cases were made that effective and timely exposure characterizations must be applied during responses to any disaster, whether terrorist, manmade, or natural in origin. The consistent application of exposure sciences across acute and chronic disaster timelines will assure that the most effective strategies are applied to collect the needed information to guide risk characterization and management approaches. Exposure sciences must be effectively applied across all phases of a disaster (defined as rescue, re-entry, recovery, and rehabitation - The 4R’s) to appropriately characterize risks and guide risk mitigation approaches. Failure to adequately characterize and control hazardous exposures increases the likelihood of excess morbidity and mortality. Advancing the infrastructure and the technologies to collect the right exposure information before, during and immediately after disasters would advance our ability to better define risks and protect responders and the public. The panel provided conclusions, recommendations, and next steps toward effective and timely integration of better exposure science into disaster preparedness, including the need for a subsequent workshop to facilitate this integration.

JOURNAL Supercritical Fluid Extraction of Aflatoxin B 1 from Soil 10/31/2008
STARR, J. M. AND M. I. Selim. Supercritical Fluid Extraction of Aflatoxin B 1 from Soil. JOURNAL OF CHROMATOGRAPHY A. Elsevier Science Ltd, New York, NY, 1209(1-2):37-43, (2008).
Abstract: This research describes the development of a Supercritical Fluid Extraction (SFE) method to recover aflatoxin B1 from fortified soil. The effects of temperature, pressure, modifier (identity and percentage), and extraction type were assessed. Using the optimized SFE conditions, the mean recovery from air dried soil was 72%. The variables associated with changes in recovery of aflatoxin B1 were co-solvents, static extraction, and temperature. The results indicate that desorption from the soil was the limiting factor in recovery and that the static phase was more important than the dynamic.

JOURNAL Apportionment of Primary and Secondary Organic Aerosols in Southern California During the 2005 Study of Organic Aerosols in Riverside (Soar-1) 10/15/2008
Docherty, K. S., E. A. Stone, I. M. Ulbrich, P. F. DECARLO, D. C. Snyder, J. J. SCHAUER, R. E. Peitier, R. J. WEBER, S. M. Murphy, J. SEINFELD, B. D. GROVER, D. J. EATOUGH, AND J. L. JIMENEZ. Apportionment of Primary and Secondary Organic Aerosols in Southern California During the 2005 Study of Organic Aerosols in Riverside (Soar-1). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 42(20):7655-7662, (2008).
Abstract: Ambient sampling was conducted in Riverside, California during the 2005 Study of Organic Aerosols in Riverside to characterize the composition and sources of organic aerosol using a variety of state-of-the-art instrumentation and source apportionment techniques.

JOURNAL Measurement of Nitrogen Mustard Degredation Products By Poly(dimethylsiloxane) Microchip Electrophoresis With Contactless Conductivity Detection 10/01/2008
Ding, Y. AND K. R. ROGERS. Measurement of Nitrogen Mustard Degredation Products By Poly(dimethylsiloxane) Microchip Electrophoresis With Contactless Conductivity Detection. ELECTROANALYSIS. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany, 20(20):2192-2198, (2008).
Abstract: The potential risk of human exposure from an accidental or intentional release of CWAs into a civilian population continues to drive the need for screening and monitoring techniques for these compounds. In particular, rapid and reliable methods for detecting CWAs such as the nitrogen mustards and their degradation products are important for cleanup and remediation of potentially contaminated sites. Microchip-based separation and detection methods have attracted increased interest over the last decade. The most frequently used methods for the unambiguous detection of nitrogen mustards and their break-down products have been gas chromatography-mass spectrometry (GC-MS) or liquid chromatography mass spectrometry (LC-MS). Due to the polarity and water solubility of the nitrogen mustards, GC-MS requires the use of derivitization prior to analysis. In addition, the presence of extraneous materials in environmental samples may interfere with the derivitization process resulting in low recoveries. Although both of these methods have been well characterized for these compounds, they require high-cost and high maintenance instrumentation, a qualified technician and are typically limited to off-site analysis.

JOURNAL Organosulfate Formation in Biogenic Secondary Organic Aerosol 09/11/2008
SURRATT, J. D., Y. Gomez-Gonzalez, A. W. Chan, R. Vermeylen, M. Shahgholi, T. E. KLEINDIENST, E. O. EDNEY, J. H. OFFENBERG, M. LEWANDOWSKI, MOHAMMAD JAOUI, W. Maenhaut, M. Claeys, R. FLAGAN, AND J. H. SEINFELD. Organosulfate Formation in Biogenic Secondary Organic Aerosol. Journal of Physical Chemistry. American Chemical Society, Washington, DC, 112(36):8345-8378, (2008).
Abstract: Organosulfates of isoprene, α-pinene, and β-pinene have recently been identified in both laboratory-generated and ambient secondary organic aerosol (SOA). In this study, the mechanism and ubiquity of organosulfate formation in biogenic SOA is investigated by a comprehensive series of laboratory photooxidation (i.e., OH-initiated oxidation) and nighttime oxidation (i.e., NO3-initiated oxidation under dark conditions) experiments using nine monoterpenes (α-pinene, β-pinene, d-limonene, l-limonene, α-terpinene, γ-terpinene, terpinolene, Δ3-carene, and β-phellandrene) and three monoterpenes (α-pinene, d-limonene, and l-limonene), respectively. Organosulfates were characterized using liquid chromatographic techniques coupled to electrospray ionization combined with both linear ion trap and high-resolution time-of-flight mass spectrometry. Organosulfates are formed only when monoterpenes are oxidized in the presence of acidified sulfate seed aerosol, a result consistent with prior work. Archived laboratory-generated isoprene SOA and ambient filter samples collected from the southeastern U.S. were reexamined for organosulfates. By comparing the tandem mass spectrometric and accurate mass measurements collected for both the laboratory-generated and ambient aerosol, previously uncharacterized ambient organic aerosol components are found to be organosulfates of isoprene, α-pinene, β-pinene, and limonene-like monoterpenes (e.g., myrcene), demonstrating the ubiquity of organosulfate formation in ambient SOA. Several of the organosulfates of isoprene and of the monoterpenes characterized in this study are ambient tracer compounds for the occurrence of biogenic SOA formation under acidic conditions. Furthermore, the nighttime oxidation experiments conducted under highly acidic conditions reveal a viable mechanism for the formation of previously identified nitrooxy organosulfates found in ambient nighttime aerosol samples. We estimate that the organosulfate contribution to the total organic mass fraction of ambient aerosol collected from K-puszta, Hungary, a field site with a similar organosulfate composition as that found in the present study for the southeastern U.S., can be as high as 30%.

JOURNAL Adult and Children's Exposure to 2,4-D from Multiple Sources and Pathways 09/01/2008
MORGAN, M. K., L. S. SHELDON, K. W. THOMAS, P. P. EGEGHY, C. W. CROGHAN, P. A. JONES, J. C. Chuang, AND N. K. WILSON. Adult and Children's Exposure to 2,4-D from Multiple Sources and Pathways. Journal of Exposure Science and Environmental Epidemiology . Nature Publishing Group, London, Uk, 18(5):486-494, (2008).
Abstract: In this study, we investigated the 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide exposures of 135 preschool-aged children and their adult caregivers at 135 homes in North Carolina (NC) and Ohio (OH). Participants were randomly recruited from six NC and six OH counties. Monitoring was performed over a 48-h period at the participants’ homes. Environmental samples included soil, outdoor air, indoor air, and carpet dust. Personal samples collected by the adult caregivers concerning themselves and their children consisted of solid food, liquid food, hand wipe, and spot urine samples. All samples were analyzed for 2,4-D (free acid form) by gas chromatography/mass spectrometry. 2,4-D was detected in all types of environmental samples but the most often in carpet dust samples, with detection frequencies of 83% and 98% in NC and OH, respectively. The median level of 2,4-D in the carpet dust samples was about three times higher in OH homes compared to NC homes (156 vs. 47.5 ng/g , p<0.0002). For personal samples, 2,4-D was more frequently detected in the hand wipe samples from OH participants (> 48%) than from NC participants (< 9%). Hand wipe levels at the 95th percentile were about five times higher for OH children (0.1 ng/cm2) and adults (0.03 ng/cm2) than for the NC children (0.02 ng/cm2) and adults (<0.005 ng/cm2). 2,4-D was detected in greater than 85% of the child and adult urine samples in both states. The median urinary 2,4-D concentration was more than twice as high for OH children compared to NC children (1.2 vs. 0.5 ng/mL, p<0.0001); however, the median concentration was identical at 0.7 ng/mL for both NC and OH adults. The intraclass correlation coefficient of reliability ( r) for an individual’s urinary 2,4-D measurements, estimated from the unadjusted (0.31 to 0.62) and specific gravity-adjusted (0.37 to 0.73) 3 values, were somewhat low for each group in this study. The variability in urinary 2,4-D measurements over the 48-h period for both children and adults in NC and OH suggests that several spot samples were needed to adequately assess these participants’ exposures to 2,4-D in residential settings. Results from this study showed that children and their adult caregivers in NC and OH were likely exposed to 2,4-D through several pathways at their homes. In addition, our findings suggest that the OH children may have been exposed to higher levels of 2,4-D through the dermal and nondietary routes of exposure than the NC children and the NC and OH adults.

JOURNAL Characterizing Air Pollution in Two Low-Income Neighborhoods in Accra, Ghana 09/01/2008
Arku, R. E., J. Vallarino, K. L. Dionisio, R. WILLIS, H. Choi, J. Wilson, C. Hemphill, S. Agyei-Mensah, J. D. SPENGLER, AND M. Ezzati. Characterizing Air Pollution in Two Low-Income Neighborhoods in Accra, Ghana. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier Science Ltd, New York, NY, 402(2-3):217-231, (2008).
Abstract: Sub-Saharan Africa has the highest rate of urban population growth in the world, with a large number of urban residents living in low-income “slum” neighborhoods. We conducted a study for an initial assessment of the levels and spatial and/or temporal patterns of multiple pollutants in the ambient air in two low-income neighborhoods in Accra, Ghana.

JOURNAL Personal Coarse Particulate Matter Exposures in An Adult Cohort 09/01/2008
WILLIAMS, R. W., M. W. CASE, K. YEATTS, F. CHEN, J. Scott, E. R. SVENDSEN, AND R. B. DEVLIN. Personal Coarse Particulate Matter Exposures in An Adult Cohort. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(28):6743-6748, (2008).
Abstract: Volunteers associated with the North Carolina Adult Asthma and Environment Study (NCAAES) participated in an investigation of personal daily exposures to coarse and fine particulate matter size fractions (PM10-2.5, PM2.5). Data from these personal measurements were then compared to community-based measures that might typically represent surrogate measurements of exposure often used in epidemiological assessments. To determine personal exposures to various particulate matter (PM) size fractions, a recently evaluated personal PM monitor capable of direct PM10-2.5 size fraction collection was used. Participants living in the central region of North Carolina and enrolled in the NCAAES were asked to wear the monitor attached to a supporting backpack for 24-h collection periods. These volunteers were monitored from two to four days with subsequent gravimetric analysis of their PM samples. Personal PM10-2.5 mass concentrations were observed to be highly variable and ranged from 7.6 to 40.2 μg/m3 over an eight month period. The median for this measurement from all participants (50th percentile) was 13.7 μg/m3. A coefficient of determination (r2) of 0.02 was established for community-based PM10-2.5 mass concentrations versus personal exposures. Similar coefficients established for PM2.5 mass revealed only a modest improvement in agreement (r2 = 0.12). Data from the exposure findings are reported here.

JOURNAL The Correlation of Secondary Organic Aerosol With Odd Oxygen in Mexico City 08/05/2008
Herndon, S. C., T. B. Onasch, E. C. Wood, J. H. KROLL, M. R. Canagaratna, J. T. Jayne, M. A. Zavala, W. Knighton, C. Massoleni, M. K. Dubey, I. M. Ulbrich, J. L. JIMENEZ, R. L. SEILA, J. A. de Gouw, B. de Foy, J. Fast, L. T. Molina, C. E. KOLB, AND D. R. WORSNOP. The Correlation of Secondary Organic Aerosol With Odd Oxygen in Mexico City. GEOPHYSICAL RESEARCH LETTERS. American Geophysical Union, Washington, DC, 35(L15804):1-6, (2008).
Abstract: Data from a mountain location intercepting the Mexico City emission plume demonstrate a strong correlation between secondary organic aerosol and odd-oxygen (O3 + NO2). The measured oxygenated-organic aerosol correlates with odd-oxygen measurements with an apparent slope of (104-180) μm-3 ppmv -1 (STP) and r2 >0.9.

JOURNAL Relationships Between Levels of Volatile Organic Compounds in Air and Blood from the General Population 07/01/2008
LIN, Y. S., P. P. EGEGHY, AND S. M. RAPPAPORT. Relationships Between Levels of Volatile Organic Compounds in Air and Blood from the General Population. Journal of Exposure Science and Environmental Epidemiology . Nature Publishing Group, London, Uk, 18(4):421-429, (2007).
Abstract: Background: The relationships between levels of volatile organic compounds (VOCs) in blood and air have not been well characterized in the general population where exposure concentrations are generally at ppb levels. Objectives: This study investigates relationships between the levels of 9 VOCs, namely, benzene, chloroform, 1,4-dichlorobenzene (1,4-DCB), ethylbenzene, methyl tert-butyl ether (MTBE), tetrachloroethene, toluene, and m-/p- and o-xylene, in blood and air from a stratified random sample of the general U.S. population. Methods: We used data collected from 354 participants, including 89 smokers and 265 nonsmokers, aged 20-59 years, who provided samples of blood and air in the National Health and Nutrition Examination Survey (NHANES) 1999-2000. Demographic and physiological characteristics were obtained from self-reported information; smoking status was determined from levels of serum cotinine. Multiple linear regression models were used to investigate the relationships between VOC levels in air and blood, while adjusting for effects of smoking and demographic factors. Results: Although levels of VOCs in blood were positively correlated with the corresponding air levels, the strength of association (R 2) varied from 0.02 (ethylbenzene) to 0.68 (1,4-DCB). Also, the blood-air relationships of benzene, toluene, ethylbenzene, and the xylenes (BTEX) were influenced by smoking, exposure-smoking interactions, and by gender, age, and BMI, whereas those of the other VOCs were not. Interestingly, the particular exposure-smoking interaction for benzene was different from those for toluene, ethylbenzene, and the xylenes. Whereas smokers retained more benzene in their blood at increasing exposure levels, they retained less toluene, ethylbenzene, and xylenes at increasing exposure levels. Conclusions: Investigators should consider interaction effects of exposure levels and smoking when exploring the blood-air relationships of the BTEX compounds in the general population.

JOURNAL The Role of Exposure Science in Air Quality Management 07/01/2008
WATKINS, T. H., S.T. RAO, AND R. Wyzga. The Role of Exposure Science in Air Quality Management. EM: AIR AND WASTE MANAGEMENT ASSOCIATIONS MAGAZINE FOR ENVIRONMENTAL MANAGERS. Air & Waste Management Association, Pittsburgh, PA, (July 2008):24-27, (2008).
Abstract: Air quality standards and regulations are designed to protect public health and the environment. However, there are issues regarding whether the current standards and regulations should be adjusted to be more protective or to more effectively target air quality management activities. People experience health impacts because of their exposure to air pollutants. Therefore, an understanding of exposure is vital for properly addressing air quality management issues. This article presents concepts of exposure and how these concepts could be applied to gain a better understanding of the relationships between air quality and human health, which, in turn, should help improve air quality management practices. While air pollution impacts both humans and ecological resources, the focus here is on human health outcomes.

JOURNAL Volatile Polar Metabolites in Exhaled Breath Condensate (Ebc): Collection and Analysis 06/01/2008
PLEIL, J. D., H. HUBBARD, J. R. Sobus, K. Sawyer, AND M. C. MADDEN. Volatile Polar Metabolites in Exhaled Breath Condensate (Ebc): Collection and Analysis. Journal of Breath Research. Institute of Physics Publishing, Bristol, Uk, 2(2):1-9, (2008).
Abstract: Environmental exposures, individual activities, and disease states can perturb normal metabolic processes and be expressed as a change in the patterns of polar volatile organic compounds (PVOCs) present in biological fluids. We explore the measurement of volatile endogenous biomarkers to infer previous exposures to complex mixtures of environmental stressors. It is difficult to extract such compounds for ultra-trace level analysis due to their high solubility in water especially when assaying complex liquid biological media such as exhaled breath condensate (EBC). Existing methods tend to be limited in sample volume processed and restricted in sample throughput. We have developed an alternative passive extraction method wherein a 2 ml sample is injected into a 75 ml glass bulb creating a small pool of liquid; a standard Tenax® sampling tube is inserted above the fluid and allowed to equilibrate with the headspace for ~ 24 hours. The biomarker compounds are preferentially transferred by diffusion from the aqueous sample onto the Tenax® adsorbent; blanks and calibration samples are similarly processed. Numerous samples can be simultaneously prepared and stored awaiting routine analysis for a suite of alcohols and aldehydes using thermal desorption GC-MS. We have optimized the procedures and have estimated the sensitivity, precision, and extraction efficiency resulting from the preparation and analytical procedures using synthetic samples. We subsequently demonstrated the method using anonymous biological specimens of EBC from healthy adults. The ultimate goal is to develop normal ranges and patterns for PVOCs to infer population based environmental health states with simple spot measurements based on outlier determinations.

JOURNAL An Interlaboratory Study of Perfluorinated Alkyl Compound Levels in Human Plasma 06/01/2008
Longnecker, M. P., C. S. Smith, G. E. Kissling, J. HOPPIN, J. L. Butenhoff, E. Decker, D. J. Ehresman, M. E. Ellefson, J. Flaherty, M. S. Gardner, E. Langlois, A. LeBlanc, A. B. LINDSTROM, W. K. Reagen, M. J. STRYNAR, AND W. B. Studabaker. An Interlaboratory Study of Perfluorinated Alkyl Compound Levels in Human Plasma. ENVIRONMENTAL RESEARCH. Academic Press Incorporated, Orlando, FL, 107(2):152-159, (2008).
Abstract: The present study was designed to investigate intra- and interlaboratory variability in results from six laboratories experienced in the analysis of perfluorinated alkyl compounds in blood matrices and that use stringent procedures to control and assure accuracy and precision. Each received an identical set of 60 plasma specimens that were analyzed in 6 completely independent batches. Split specimens were included so that within- and between-batch coefficients of variation could be calculated. All laboratories used liquid chromatography-tandem mass spectrometry (LC-MS/MS). In general, the concentrations of perfluorooctanesulfonate (PFOS), perfluorooetanoate (PFOA), and perfluorohexanesulfonate (PFHxS) measured in the specimens showed a high degree of concordance across laboratories. The average within- and between-batch coefficient of variation for PFOS was 9.1% and 9.3%; for PFOA was 14.5% and 14.5%; and for PFHxS was 14.5% and 17.0%. The recent availability of labeled internal standards, among other advances, has facilitated improvement in the accuracy and precision of the assays. Considering the degree of between-subject variation in levels among people in background exposed populations, the results indicate that biomarker-based epidemiologic studies of associations with health could have reasonable precision.

JOURNAL Evaluation of a Direct Personal Coarse Particulate Matter Monitor 06/01/2008
CASE, M. W., R. W. WILLIAMS, K. YEATTS, F. CHEN, J. W. SCOTT, E. R. SVENDSEN, AND R. B. DEVLIN. Evaluation of a Direct Personal Coarse Particulate Matter Monitor. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 42(19):4446-4452, (2008).
Abstract: One aspect of the North Carolina Adult Asthma and Environment study (NCAAES) was to evaluate personal exposures to coarse particulate matter (PM 10-2.5) and their associated variability. As part of this, we examined the ability of a community-based monitor to act as a surrogate for an individual’s true exposure to this size fraction in linked health effect studies. To assess personal exposures to various particulate matter (PM) size fractions, a personal PM monitor was evaluated. This monitor featured a multi-stage cascade impactor that allowed for the simultaneous collection of PM10-2.5 and PM2.5 size fractions. The monitor was evaluated for collocated bias and comparability with a dichotomous (dichot) sampler (device for dividing aerosol particulate matter population into two size fractions during sampling) at an outdoor monitoring site. Results of this evaluation indicated that the prototype was capable of agreement within ± 20% of that provided by the reference methodology as well as 20% daily precision for PM10-2.5 mass measurements.

JOURNAL Perfluorinated Compounds in House Dust from Ohio and North Carolina, USA 05/15/2008
STRYNAR, M. J. AND A. B. LINDSTROM. Perfluorinated Compounds in House Dust from Ohio and North Carolina, USA. ENVIRONMENTAL SCIENCE AND TECHNOLOGY. John Wiley & Sons, Ltd., Indianapolis, IN, 42(10):3751-3756, (2008).
Abstract: The perfluoroalkyl acids (PFAAs), including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), have come under increasing scrutiny due to their persistence in the environment, global distribution, and animal toxicity. Given that human exposure routes for these compounds remain poorly characterized, the potential role of house dust needs to be more completely evaluated. In this study, new methods for the analysis of 10 target PFAAs and 3 fluorinated telomer alcohols (FTOHs) were developed and applied to dust samples collected from homes (n=102) and day care centers (10) in Ohio and North Carolina. FTOHs were analyzed by GC/MS after sonic extraction and solid phase extraction cleanup. PFAAs were analyzed after extraction by LC-MS/MS. PFOS and PFOA were found to be the most prominent compounds in this analysis, occurring in over 95% of the samples at median concentrations of 201 and 142 ng/g of dust, respectively. Maximal concentrations of PFOS were at 12,100 ng/g, PFOA at 1,960 ng/g, and perfluorohexanesulfonate (PFHS) at 35,700 ng/g. The 8:2 FTOH, which is volatile and can degrade to PFOA, had a maximum concentration of 1660 ng/g dust. These results indicate that perfluorinated compounds are present in house dust at levels that may be important for human exposure.

JOURNAL Formation of Secondary Organic Aerosol from Irradiated a-Pinene/Tolueme/Nox Mixtures and the Effect of Isoprene and Sulfur Dioxide 05/10/2008
JAOUI, M., E. O. EDNEY, T. E. KLEINDIENST, M. LEWANDOWSKI, J. H. OFFENBERG, J. D. SURRATT, AND J. SEINFELD. Formation of Secondary Organic Aerosol from Irradiated a-Pinene/Tolueme/Nox Mixtures and the Effect of Isoprene and Sulfur Dioxide. JOURNAL OF GEOPHYSICAL RESEARCH. American Geophysical Union, Washington, DC, 113(D09303):1-12, (2008).
Abstract: Secondary organic aerosol (SOA) was generated by irradiating a series of a-pinene/toluene/NOx mixtures in the absence and presence of isoprene or sulfur dioxide. The purpose of the experiment was to evaluate the extent to which chemical perturbations to this base-case (a-pinene/toluene) mixture led to changes in the gas-phase chemistry which strongly influences mass and composition of SOA and secondary organic carbon (SOC) formed.

JOURNAL Primary and Secondary Contributions to Ambient PM in the Midwestern United States 05/01/2008
LEWANDOWSKI, M., MOHAMMAD JAOUI, J. H. OFFENBERG, T. E. KLEINDIENST, E. O. EDNEY, R. J. SHEESLEY, AND J. J. SCHAUER. Primary and Secondary Contributions to Ambient PM in the Midwestern United States. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 42(9):3303-3309, (2008).
Abstract: Ambient PM2.5 samples were collected in five Midwestern US cities throughout 2004: East St. Louis, Illinois; Detroit, Michigan; Cincinnati, Ohio; Bondville, Illinois; and Northbrook, Illinois. Monthly composites were analyzed using chemical derivatization coupled with GC-MS analysis to estimate the contributions of several sources to the total ambient organic carbon. A chemical mass balance (CMB) approach was used to estimate contributions from several primary sources. An additional, organic tracer-based technique was employed to estimate secondary contributions, including secondary organic carbon derived from isoprene, a-pinene, β-caryophyllene, and toluene. The sum of these contributions was compared with the total. Organic carbon measured at each sampling site, and reasonable carbon mass balances were observed for four of the five sites. In Bondville, Northbrook, Cincinnati, and Detroit, a strong correlation was observed between the sum of the estimated primary and secondary contributions and the measured organic carbon (R2 = 0.73). The estimated secondary organic carbon concentrations were observed to vary considerably with season, with the strongest contributions coming from isoprene and a-pinene during the summer. While further research is required, there is some evidence the contribution estimates for a-pinene, β-caryophyllene, and toluene SOC may to some degree represent the contributions from the broader classes of monoterpenes, sesquiterpenes, and aromatics.

JOURNAL A New Method of Longitudinal Diary Assembly for Human Exposure Modeling 05/01/2008
GLEN, G., L. SMITH, K. K. ISAACS, T. R. MCCURDY, AND J. LANGSTAFF. A New Method of Longitudinal Diary Assembly for Human Exposure Modeling. Journal of Exposure Science and Environmental Epidemiology . Nature Publishing Group, London, Uk, 18(3):299-311, (2008).
Abstract: Human exposure time-series modeling requires longitudinal time-activity diaries to evaluate the sequence of concentrations encountered, and hence, pollutant exposure for the simulated individuals. However, most of the available data on human activities are from cross-sectional surveys that typically sample one day per person. A procedure is needed for combining cross-sectional activity data into multiple-day (longitudinal)sequences that can capture day-to-day variability in human exposures. Properly accounting for intra- and inter-individual variability in these sequences can have a significant effect on exposure estimates and on the resulting health risk assessments. This paper describes a new method of developing such longitudinal sequences, based on ranking one-day activity diaries with respect to a user-chosen key variable. Two statistics, "D" and "A", are targeted. The D statistic reflects the relative importance of within- and between-person variance with respect to the key variable. The A statistic quantifies the day-to-day (lag-one) autocorrelation. The user selects appropriate target values for both D and A. The new method then stochastically assembles longitudinal diaries that collectively meet these targets. Based upon numerous simulations, the D and A targets are closely attained for exposure analysis periods >30 days in duration, and reasonably well for shorter simulation periods. Longitudinal diary data from a field study suggest that D and A are stable over time, and perhaps over cohorts as well. The new method can be used with any cohort definitions and diary pool assignments, making it easily adaptable to most exposure models. Implementation of the new method in its basic form is described, and various extensions beyond the basic form are discussed.

JOURNAL Modeling Energy Expenditure and Oxygen Consumption in Human Exposure Models: Accounting for Fatigue and Epoc 05/01/2008
ISAACS, K. K., G. GLEN, T. R. MCCURDY, AND L. SMITH. Modeling Energy Expenditure and Oxygen Consumption in Human Exposure Models: Accounting for Fatigue and Epoc. Journal of Exposure Science and Environmental Epidemiology . Nature Publishing Group, London, Uk, 18(3):289-298, (2007).
Abstract: Human exposure and dose models often require a quantification of oxygen consumption for a simulated individual. Oxygen consumption is dependent on the modeled Individual's physical activity level as described in an activity diary. Activity level is quantified via standardized values of metabolic equivalents of work (METS) for the activity being performed and converted into activity-specific oxygen consumption estimates. However, oxygen consumption remains elevated after a moderate- or high-intensity activity is completed. This effect, which is termed excess post-exercise oxygen consumption (EPOC), requires upward adjustment of the METS estimates that follow high energy expenditure events, in order to model subsequent increased ventilation and intake dose rates. In addition, since an individual's capacity for work decreases during extended activity, methods are also required to adjust downward those METS estimates that exceed physiologically-realistic limits over time. A unified method for simultaneously performing these adjustments is developed. The method simulates a cumulative oxygen deficit for each individual and uses it to impose appropriate timedependent reductions in the METS time series and additions for EPOC. The relationships between the oxygen deficit and METS limits are non-linear and are derived from published data on work capacity and oxygen consumption. These modifications result in improved modeling of ventilation patterns, and should improve intake dose estimates associated with exposure to airborne environmental contaminants.

JOURNAL Design and Evaluation of An Inlet Conditioner to Dry Particles for An Aerodynamic Particle Sizer 04/01/2008
Peters, T. M., A. L. Riss, R. L. Holm, M. Singh, AND R. W. VANDERPOOL. Design and Evaluation of An Inlet Conditioner to Dry Particles for An Aerodynamic Particle Sizer. JOURNAL OF ENVIRONMENTAL MONITORING. Royal Society of Chemistry, Cambridge, Uk, 10(4):541-551, (2008).
Abstract: Atmospheric particulate matter is one of six pollutants for which the Environmental Protection Agency (EPA) has set National Ambient Air Quality Standards. Particulate matter standards are specified by particle size as PM 2.5 defined as the mass concentration of ′fine′ particles smaller than 2.5 µm aerodynamic diameter, and PM10 defined as the mass concentration of particles with an aerodynamic diameter smaller than 10 µm.

PUBLISHED REPORT Sheds-Multimedia Model Version 3 (a) Technical Manual; (B) User Guide; and (C) Executable File to Launch Sas Program and Install Model 09/30/2008
ZARTARIAN, V. G., G. Glen, L. SMITH, AND J. XUE. Sheds-Multimedia Model Version 3 (a) Technical Manual; (B) User Guide; and (C) Executable File to Launch Sas Program and Install Model. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-08/118, 2008.
Abstract: Reliable models for assessing human exposures are important for understanding health risks from chemicals. The Stochastic Human Exposure and Dose Simulation model for multimedia, multi-route/pathway chemicals (SHEDS-Multimedia), developed by EPA’s Office of Research and Development (ORD), National Exposure Research Laboratory (NERL), is a state-of-science computer model for improving estimates of aggregate (single-chemical, multi-route/pathway) and cumulative (multi-chemical, multi-route/pathway) human exposure and dose. SHEDS-Multimedia is the EPA/ORD’s principal model for simulating human exposures to a variety of multimedia, multi-pathway environmental chemicals such as pesticides, metals, and persistent bioaccumulative toxins.

PUBLISHED REPORT EPA Positive Matrix Factorization (Pmf) 3.0 Fundamentals & User Guide 09/22/2008
NORRIS, G. A., R. VEDANTHAM, K. Wade, S. Brown, J. Prouty, AND C. FOLEY. EPA Positive Matrix Factorization (Pmf) 3.0 Fundamentals & User Guide. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-08/108, 2008.
Abstract: Positive matrix factorization (PMF) is a multivariate factor analysis tool that decomposes a matrix of ambient data into two matrices - factor contributions and factor profiles - which then need to be interpreted by an analyst as to what source types are represented using measured source profile information, wind direction analysis, and emission inventories.The method is reviewed briefly here and described in greater detail.

PUBLISHED REPORT Scientific and Ethical Approaches for Observational Exposure Studies 07/25/2008
FORTMANN, R. C. Scientific and Ethical Approaches for Observational Exposure Studies. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-08/062 (NTIS PB2008-112239), 2008.
Abstract: Researchers conduct observational human exposure studies to understand how and the extent to which people come into contact with chemicals and environmental stressors in their everyday lives, through the air they breathe, the food and liquids they consume, and the things they touch. The U.S. Environmental Protection Agency’s (EPA’s) National Exposure Research Laboratory (NERL) has conducted observational human exposure studies for several decades and uses the information and data from these studies to improve the Agency’s understanding of human exposures to chemicals and other stressors and ultimately to support efforts to improve public health. Because these studies involve people as research participants, they are complex and raise numerous scientific and ethical issues that have to be addressed prior to and during their design and implementation.

 

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