Proximity to traffic, air toxic exposures and the development of asthma in children (2006 - 2008)

Woskie S, University of Massachusetts, Lowell

Batterman S - University of Michigan; Ryan B - Emory University; Symanski E - University of Texas; Wang SW - University of Medicine and Dentistry New Jersey

Oxygenated Urban Air Toxics and Asthma Variability in Middle School Children: A Panel Study

The objective of this study was to evaluate the associations between ambient levels of particulate matter toxic metals (Sb, As, Cr, Co, Mn, Hg, Se, Cd and Ni) and transition metals (Ti, V and Fe), and several health endpoints that include, emergency department (ED) visits for asthma, hospital admissions for asthma and other respiratory outcomes; and, total respiratory mortality.  This was to be accomplished using time-series and source apportionment methods on a Spokane, WA daily data set some 7 years long.  The investigators analyzed archived daily fine and course particulate samples collected in Spokane over 4 years (1995-1998) collected via an EPA grant and added to this 3 years worth of samples that were collected during the period of NUATRC support.  Thus, a total of 7 years worth of data was available for analysis.  PM metals content on both archived samples and samples collected during this period of support was determined via a combination of energy-dispersive x-ray fluorescence (EDXRF) and instrument neutron activation (INAA). These INAA analyses were conducted via support from the US EPA. Susceptible populations that were targeted for study include both elderly and non-elderly age groups and individuals with pre-existing chronic conditions such as asthma. Health outcomes that were examined include:

The investigators are testing the hypothesis that the rate of Harris County residents hospitalized during the study period differs geographically among the 337 4x4 km domains, and correlates with exposure to modeled air pollutants, even after adjusting for available individual and domain-specific demographic confounders. The investigators will use the USEPA’s Community Multiscale Air Quality with Air Toxics (CMAQ-AT) model to estimate pollutant concentrations, and ArcGIS (ESRI, Redlands, CA) geospatial modeling software to extract and/or combine the exposure, admissions, and demographic data for each of the domains for subsequent analysis. SAS 9.1.2 (SAS Institute, Cary, NC) will be the primary statistical software used.

Baylor College of Medicine Environmental Health Section (BCM-EHS) is collaborating on the project with the University of Texas School of Public Health (UTSPH) and the University of Houston Institute of Multidimensional Air Quality Studies (UH-IMAQS).

The overall objective of this proposal is to assess the relationship between exposures to ambient levels of certain urban air toxics (UATs), as measured by outdoor air monitors, and utilization of urgent care facilities by children enrolled in Medicaid in Dearborn, Michigan.  The two principal hypotheses and related aims follow:

Hypothesis 1:  Levels of selected UATs, including 1,3-butadiene, acetaldehyde, acetonitrile, benzene, carbon tetrachloride, chloroform, formaldehyde, methylene chloride, tetrachloroethene, and trichloroethene, are related to measures of urgent care utilization for asthma among a pediatric Medicaid population in Dearborn, MI.

The specific aims are:
Develop a set of exposure measures based on daily measurement data of the selected UATs available at the Dearborn monitor between April 19, 2001, and April 19, 2002, along with other pollutants known or likely to be associated with asthma (O₃, PM, etc.).
1). Obtain Medicaid files on children from 1 –17 years of age residing in Dearborn between April 19, 2001, and April 19, 2002, on daily utilizations of urgent care facilities, including hospital visits and urgent care visits.
2). Link the exposure measures and Medicaid files. 
3). Analyze the relationships between daily fluctuations in concentrations of the UATs and daily urgent care utilization for asthma using appropriate statistical models.

Hypothesis 2:  UAT concentrations represent contributions from various emission source groupings that in turn are related to urgent care utilization for asthma among the same pediatric Medicaid population. 

The specific aims for this hypothesis are:
1). Develop daily source apportionment scores for the selected Dearborn UATs using multivariate models and ambient air quality data.
2). Analyze the relationship between source category scores and urgent care utilizations for asthma using appropriate statistical models.
3). Assess the variability in the apportionment scores using alternative method to derive the source scores.

The Investigators are collaborating with the University of Michigan on this project.

This effort is essential to the NUATRC’s commitment to perform furtther data analysis for data obtained from previously funded NUATRC Projects RIOPA. The database is being developed in order to facilitate the ROPIA data use for further analyses, particularly for scientists who did not participate in the RIOPA project.

The overall objective of this project is to conduct the verification testing of the Sioutas Personal Cascade Impactor Sampler (PCIS) and the Leland Legacy Pump, under the auspices of the U.S. Environmental Protection Agency (EPA) through the Environmental Technology Verification (ETV) Program.  The verification test originally included four Subtasks: A) Pump Testing, B) Sampling Efficiency Comparisons, C) Sampling Metals in Ambient Air, and D) PCIS Ease of Use, Reliability and Subject Acceptance/Compliance.  A fifth Subtask, the repeat of Subtask A using SKC-modified Leland Legacy Pumps, was added to the verification testing in August, 2006.

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• Obtain all the literature available in the public domain describing laboratory evaluations and measurements of VOCs in ambient, indoor, and personal air using the 3500 or 3520 3M OVM. This literature includes publications in peer reviewed journals, project reports, and doctoral dissertations;
• Review and critique the literature on the accuracy and precision of the OVMs for each of the compounds in the suite of VOCs targeted by each individual report as a function of quality assurance/quality control parameters; concentration, sample duration, temperature, humidity, and altitude (barometric pressure);
• Develop a critical review that assesses the scientific literature pertaining to the performance of the OVMs both in the laboratory and in the field. The practical goal of this critical review is to develop a manuscript that summarizes the performance parameters and limitations of the OVM that will be submitted for publication to suitable scientific journals.

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This project was funded under the RFA 2005-01: Proximity to Vehicular Traffic, Exposures to Air Toxics and Non Cancer Health Effects, which was released in January of 2005.   A three year contract was signed September 2006 with the University of Berkeley for this projectThe investigators plan to study the relationship between exposure to vehicular polycyclic aromatic hydrocarbons (PAHs) and the short and long term respiratory effects on children who have well-characterized asthma.  This research will complement an on-going study of 302 children with asthma, ages 6-11 at intake, in Fresno, CA, who are already recruited and for whom voluminous health and exposure data are available (the Fresno Asthmatic Children’s Environment Study-FACES). The investigators will test the following hypothesis:

Acute exposure to PAHs leads to acute increases in symptoms, increased medication use, and lung function declines. These adverse reactions to acute PAH exposures, when recurrent over 3-5 years, have the cumulative effects of more severe asthma and reduced lung function growth.

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This project was funded in response to RFA 2005-01: Proximity to Vehicular Traffic, Exposures to Air Toxics and Non Cancer Health Effects, released in January of 2005. A three year contract was signed with University of Massachusetts at Lowell on September 1, 2006.

The objective of the proposed research is to examine how traffic related air toxics are associated with changes in respiratory symptoms and exhaled nitric oxide, a marker of airway inflammation, in children. The project uses a repeated measures design to study sibling pairs where the older sibling is asthmatic and the younger sibling is at high risk of developing asthma. To examine the role of traffic, a gradient of exposures will be achieved by selecting sibling pairs whose geocoded locations represent a range of traffic proximity/traffic volume categories. Sibling pairs will be identified and recruited using a large Central Massachusetts group practice / HMO, the Fallon Clinic. For each child in the sibling pair, the field team will conduct 2 home visits (one in the heating season and one in the non-heating season) to collect health (exhaled NO and symptom questionnaire) and exposure data (personal exposures to volatile air toxics (benzene, toluene, ethylbenzene, xylenes, formaldehyde, acetaldehyde and acrolein). In addition, exposures to criteria air pollutants will be collected from 2 Massachusetts Department of Environmental Protection (MADEP) centralized monitoring sites to control for confounding. Exposure-response analysis will use generalized estimating equations and mixed models to examine associations between exhaled nitric oxide, symptoms and subject location relative to roadways categorized by traffic patterns as well as by various exposure metrics for the air toxics, while controlling for potential confounders.

The project will be conducted in collaboration with the Fallon Community Health Plan (FCHP) the largest HMO located in Central Massachusetts. The Fallon Clinic Research Department (FCRD) has a unique search engine for epidemiologic and clinical studies in the FCHP member population, the "Milton Mart whch will be  used  to design and run the data queries to identify eligible sibling pairs

Under the National Center for Health Statistics (NCHS), -NUATRC collaborative agreement “A Study of Personal Exposure to Air Toxics among a Subset of the Residential U.S. Population (VOC Project -1997-2005 , data were collected for the three-year period 1999-2001 for this population. The VOC Project provides a profile of personal exposures to a group of VOCs in this national population. Because of the wide variety of demographic and lifestyle information collected from these subjects in the main part of the NHANES survey, there are many opportunities for additional research with these data

In April 2005, NCHS released the two-year data set for the VOC Project on its website: http://www.cdc.gov/nchs/about/major/nhanes/NHANES99_00.htm.   The VOC Project data files are listed on this site under Laboratory Files as “Lab 21, Volatile Organic Compounds (subsample)”.VOC exposure data and activity data obtained from the VOC Project questionnaire are included for 659 participants.   Personal exposure assessments are included for the following VOCs: benzene, chloroform, 1,4-dichlorobenzene, ethylbenzene, methyl tertiary-butyl ether (MTBE), tetrachloroethylene, toluene, trichloroethylene, o-xylene, and m/p-xylene.

In January 2006, The NUATRC released RFA 2006-1, "Relationship Between Personal Exposures to VOCs and Behavioral, Socioeconomic, and Demographic Characteristics: Analysis of the NHANES VOC Project Data Set.” Following four projects have been funded under this project.

Dr. Stuart Batterman, University of Michigan
The Study will characterize distributions of the ten on the highest exposures, particularly those in the top decile.  The study characterizes co-exposures among subjects, i.e., those subjects with the highest exposures to one, two or more of the VOCs and will evaluate methods for examining these co-exposures (ex., Monte Carlo methods).  They will attempt to identify risk factors - demographic, behavioral, or socioeconomic - for high exposure for specific VOCs.  The study will also evaluate whether exposures recorded in the VOC Project are comparable to those obtained in smaller, but similarly designed studies that have been described in the literature.

Dr. Barry Ryan, Emory University
The study consists of three individual studies.  Investigation 1 is an examination of the relationship between measured personal exposures to the BTEX compounds (benzene, toluene, ethylbenzene, o-xylene and m, p-xylene) and demographic, housing and exposure factor predictors such as smoking, pumping gasoline, and using paints and solvents.Investigation 2 will characterize chloroform exposures among U.S. adults and will compare inhalation intakes with estimated intakes via ingestion and dermal exposures to chlorinated drinking water.  This study will test the hypothesis that adults on average are not exposed to levels of health concern via inhalation, but may be exposed to levels of concern when all three pathways are considered. The third investigation will evaluate the relationship between serum C-reactive protein (CRP) levels and personal VOC exposures among healthy adult subjects in the NHANES population.  The hypothesis to be tested is that increasing exposures are significantly associated with increasing serum CRP after controlling for age, gender, diet and exposures to other environmental contaminants.  An extensive literature review on mechanisms of toxicity, and also on major predictors of elevated serum CRP will be carried on.

Dr. Elaine Symanski, University of Texas Houston School of Public Health
The studye the distribution of exposures to selected VOCs within the VOC Project population.  The population will then be characterized according to socio-demographic and other characteristics, and profiles of the highest and lowest will be compared.  For all pairs of VOCs, bivariate relationships will be examined.   A list of potential determinants of personal exposure to VOCs will then be prepared, based on the literature.  The effect of each determinant, as well as the effects of multiple determinants, on VOC exposure will be assessed using appropriate regression techniques.   Finally, the potential for differences in key determinants of exposure by smoking or ethnicity status will be evaluated.

Dr. Sheng-Wei Wang, University of Medicine and Dentistry New Jersey
The study will between personal exposure to the selected VOCs among individuals in the VOC Project population and demographic, socioeconomic and behavioral variables; and to identify the best predictors among these variables in determining personal exposure levels of the selected VOCs.  The hypothesis being tested here is that lifestyle factors can contribute significantly to the personal exposures to VOCs.

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This is a collaborative effort among EPA Region 6, the Texas Commission on Environmental Quality (TCEQ), the NUATRC, the City of Houston, Texas Environmental Research Consortium (TERC), Harris County, and the East Harris County Chemical Manufacturer’s Association (EHCMA).  The two-year study will investigate the correlation between outdoor, indoor, and personal exposure to specific air toxics and compare exposure and self-reported health data from a population living in a defined neighborhood impacted by industrial sources to a matched population living in an area minimally impacted by industrial sources.  HEATS will provide data on source contribution ratios, averaging time comparisons, and amount and duration of exposure.  The results will show whether, and to what degree, actual personal exposure differs from ambient results collected at fixed-monitoring sites.  Linking personal exposure data for air toxics to ambient air monitoring data will allow resources to be more effectively targeted in specific geographical or societal areas of concern.  Specifically, the study will provide information that TCEQ and EPA can use to determine the relative contribution of point, mobile and area source emissions to actual exposure, develop strategies to reduce population risks, design health effects studies that incorporate ambient and personal exposure information, evaluate the performance of currently used exposure models and develop air toxics exposure and concentration models. 

The study will also have a parallel communication, outreach and education plan, as recommended by the NUATRC SAP.  This plan will help ensure that the study aims, processes and goals are adequately communicated to the study participants and greater community, which will help ensure good data quality.  It will also ensure that the study results are communicated fully to the regulatory community, local leaders and the community, which will help maximize the utility of the study.

The UT Investigators are collaborating with Investigators from Research Triangle Institute, in RTP NC and the University of Texas Medical Branch in Galveston.

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