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Extramural Research

2007 Progress Report: Pesticide Exposure Pathways Research Project

EPA Grant Number: R831709C004
Subproject: this is subproject number 004 , established and managed by the Center Director under grant R831709
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: University of Washington Center for Child Environmental Health Risks Research
Center Director: Faustman, Elaine
Title: Pesticide Exposure Pathways Research Project
Investigators: Faustman, Elaine
Institution: University of Washington
EPA Project Officer: Callan, Richard
Project Period: November 1, 2003 through October 31, 2008 (Extended to October 31, 2010)
Project Period Covered by this Report: November 1, 2006 through October 31,2007
RFA: Centers for Children's Environmental Health and Disease Prevention Research (2003)
Research Category: Children's Health , Health Effects



The objective of this research project is to improve our understanding of critical pathways of pesticide exposure for children.

Progress Summary:

Washington aerial spray study: modeling pesticide spray drift deposition from an aerial application:
An aerial organophosphorus pesticide (OP) application of methamidophos in central Washington State was monitored. The sprayed potato crop surrounded a rural agricultural community where residences were within 100 meters of the sprayed fields. Spray drift from the spray event was sucessfully modeled using the U.S. Environmental Protection Agency’s Fugitive Dust Model (FDM); deposition from drift was modeled during the day of the event and was found to correlate well when compared with deposition samples in the community. Post-spray volatization of pesticides also was found to contribute to pesticide air levels and was modeled and measured in the community. A manuscript describing the study was published in the Journal of Exposure Science and Environmental Epidemiology (Weppner et al), a second paper describing the drift modeling was published in Atmospheric Environment (Tsai, et al) and a third paper in progress describes the volatization modeling (Ramaprasad et.al.). A new manuscript (under submission) describes a risk assessment for children in the nearby community from inhalation exposures. We are preparing a final manuscript describing combined exposures from inhalation and dermal pathways and comparing the exposure estimates with biological monitoring data from children in the community.
Washington spray drift study: airblast spray aerosols and deposition parameters: 
We conducted field observations of an orchard air blast spray event in 2005 in Prosser, WA in collaboration with Dr. Allan Felsot at Washington State University (WSU). Detailed follow-up measurements of the air blast spray equipment were conducted in 2006. A doctoral student working on this project, Ming Yi Tsai, conducted field sample collection and modeling of this spray application. This study included real-time Lidar observations, active air sampling, and passive deposition samples done concurrently by WSU and UW research teams. The results of this study were used to develop a new Orchard Airblast Dispersion Model (OSDM) based on the FDM model from US EPA. Ming Yi Tsai has completed his dissertation on this study and recently defended it; a manuscript prepared from his work describes the air blast study and compares our results to current models of air blast application. Findings were presented at the Conference on Health & Safety in Western Agriculture: Research to Practice September 20-22, 2006 in Asilomar, California.
Community inhalation exposures to OP pesticides in Washington State:
We used our GIS dataset of pesticide application areas and historical meteorological data to locate areas with potential exposures to OP pesticides in different communities. The Wenatchee valley, which is an area of concentrated tree fruit production, was selected for an air monitoring campaign conducted during the most recent spray season (April-Sept, 2007). Pesticide volatilization and ambient particle data were collected at two locations, including a school, and used to evaluate inhalation risks for children. The data revealed that chronic and sub-chronic risk estimates based only on the inhalation pathway would not exceed acceptable limits under adverse weather conditions. This work was the basis of a completed Master’s thesis (Lisa Tolbert MS),  and a manuscript has been prepared from her thesis for submission to the Journal of Exposure Science which describes the air monitoring and risk assessment findings.
Washington aerial spray study: observations and modeling pesticide spray drift impacts from an aerial application:
We have collected personal exposure and residential sample data in communities impacted by pesticide spray drift and post-spray volatization and developed advanced dispersion models to estimate community exposures via multiple pathways. We have validated these models with personal exposure data and residential samples collected in agricultural communities. These models allow us to evaluate potential pesticide exposures due to deposition and surface contamination (dermal pathway) and from volatization (inhalation pathway). This work demonstrates the importance of multiple pathways for assessment of chronic pesticide exposures of children in the community and the influence of varying meteorological conditions that impact surface deposition and vapor phase emissions from spray applications.
Washington spray drift study: observations and modeling of pesticide spray drift impacts from air-blast applications:
We have extended our previous work on aerial applications with studies of ground applications of pesticides using air-blast sprayers. Air blast spraying is commonly used in the tree fruit industry and accounts for a most of the pesticide drift incidents reported in Washington state. Our studies show that previous models did not adequately account for the extent of pesticide transport and deposition onto surfaces from air-blast applications. We have developed a new model for air-blast applications, which provides a more accurate and comprehensive description of spray drift from air blast applications. This model is now being applied to evaluate community exposures in areas where air blast spraying is common.

Future Activities:

Washington aerial spray study: Modeling pesticide spray drift deposition from an aerial application:
Our study of aerial spraying in Washington State has yielded several papers, and two additional manuscripts are in preparation or under submission. We plan to conduct additional field observations of aerial spraying in neighboring Idaho in the spring spray season. These observations will parallel our previous work in a new community site, with different climate factors that favor low evaporation and volatization of pesticides. Volatization losses are an important sink for pesticide residues, but we have shown that that inhalation exposures alone are not likely to contribute to high risks among children in our region. Therefore improved estimates of surface residues are a significant focus of our exposure pathway studies in children. The climatic conditions in the planned field study favor persistence of pesticide residues on surfaces, and would contribute to higher exposure potential via the dermal pathway.
Washington spray drift study: observations and modeling pesticide spray drift impacts from air-blast applications:
The data analysis for this study was recently completed and is described in a doctoral dissertation. We have prepared two manuscripts for submission from this dissertation, and a third manuscript describing the comparison of the OSDM air-blast spraying model with real-time Lidar sampling is planned for the fall of 2007.
Construction of a GIS dataset with estimates of pesticide use in Washington State:
This work provided baseline geo-referenced crop information, and when linked with typical pesticide applications in crops, provides estimates of pesticide use in Washington State. This data, along with census information, provides an overview of communities with children where pesticide impacts are likely. Air and aerosol emission factors for various pesticide application scenarios will be added based on our current spray drift modeling efforts. We also can examine the potential influence of different crop management practices such as integrated pest management. Finally, we can add existing urine and house dust data into the GIS analysis to examine potential correlations between pesticide usage and exposure patterns due to different modeled pathways (i.e. inhalation, primary drift, secondary dust suspension/surface deposition, and take home pathways).

Journal Articles on this Report : 2 Displayed | Download in RIS Format

Other subproject views: All 8 publications 4 publications in selected types All 4 journal articles
Other center views: All 175 publications 127 publications in selected types All 107 journal articles

Type Citation Sub Project Document Sources
Journal Article Elgethun K, Yost MG, Fitzpatrick CTE, Nyerges TL, Fenske RA. Comparison of global positioning system (GPS) tracking and parent-report diaries to characterize children's time-location patterns. Journal of Exposure Science and Environmental Epidemiology 2007;17(2):196-206. R831709 (2005)
R831709 (2006)
R831709 (2007)
R831709C004 (2006)
R831709C004 (2007)
  • Abstract from PubMed
  • Abstract: Nature.Com-Full Text HTML
  • Journal Article Weppner S, Elgethun K, Lu C, Herbert V, Yost MG, Fenske RA. The Washington aerial spray drift study:children's exposure to methamidophos in an agricultural community following fixed-wing aircraft applications. Journal of Exposure Science and Environmental Epidemiology 2006;16(5):387-396. R831709 (2005)
    R831709 (2006)
    R831709 (2007)
    R831709C004 (2006)
    R831709C004 (2007)
  • Abstract from PubMed
  • Full-text: Nature Communications-Full Text HTML
  • Abstract: Nature Communications-Abstract
  • Other: Nature Communications-Full Text PDF
  • Supplemental Keywords:

    children’s health, epidemiology, genetics, health risk assessment, risk assessment, assessment of exposure, asthma, children’s environmental health, diesel exhaust, environmental risks, exposure assessment, genetic mechanisms, genetic risk factors, genetic susceptibility, maternal exposure, nutritional risk factors, Environmental Management, Scientific Discipline, Health, RFA, Risk Assessment, Health Risk Assessment, Children's Health, Biochemistry, Environmental Chemistry, health effects, children's environmental health, assessment of exposure, developmental neurotoxicity, agricultural community, community-based intervention, pesticide exposure, genetic polymorphisms, biological response, environmental health, environmental risks, children's vulnerability
    , RFA, Health, Scientific Discipline, ENVIRONMENTAL MANAGEMENT, Environmental Chemistry, Health Risk Assessment, Biochemistry, Children's Health, Risk Assessment, health effects, pesticide exposure, environmental health, community-based intervention, developmental neurotoxicity, environmental risks, biological response, Human Health Risk Assessment, biomonitoring, children's vulnerablity, assessment of exposure, exposure pathways, children's environmental health, agricultural community

    Progress and Final Reports:
    Original Abstract
    2004 Progress Report
    2005 Progress Report
    2006 Progress Report

    Main Center Abstract and Reports:
    R831709    University of Washington Center for Child Environmental Health Risks Research

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R831709C001 Molecular Mechanisms of Pesticide-Induced Developmental Toxicity
    R831709C002 Genetic Susceptibility to Pesticides
    R831709C003 Community-Based Participatory Research Project
    R831709C004 Pesticide Exposure Pathways Research Project

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    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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