2006 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 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, 2005 through October 31,2006
RFA: Centers for Children's Environmental Health and Disease Prevention Research (2003) RFA Text |  Recipients Lists
Research Category: Children's Health , Health Effects , Health


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:
A routinely scheduled 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 200 meters of the sprayed fields. Spray drift deposition was modeled with regard to model selection, calibration, and prediction for a particular application event. The U.S. Environmental Protection Agency’s Fugitive Dust Model (FDM) was chosen for its flexibility and model calibration was accomplished by varying the aerosol size distribution in comparison with deposition samples. From the calibrated model, a map of total pesticide deposition within the community indicated spray drift occurring despite adherence to general precautionary pesticide application guidelines. The calibrated model also provided 15-minute time resolved deposition images over the five-hour application period. The time-resolved maps revealed that actual community deposition occurred in only two 15-minute time periods, due to the wind direction oriented towards the community.  A manuscript describing the study was published in EHP (Weppner et al) and a second paper describing the drift modeling was published in Atmospheric Environment (Tsai, et al).
Washington spray drift study: airblast spray aerosols and deposition parameters. 
We conducted field observations of a spray event in 2004/5 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, lead the field sample collection by UW.  WSU completed the deposition sample analysis in late spring 2005. This air blast application in a working orchard with active ingredient (phosmet) provided by us, but was done after the normal harvest ends (due to pre-harvest treatment restrictions). The spray was performed by a WSU applicator under our direction regarding suitable meteorology and sample collection procedures. This study included real-time Lidar observations, active air sampling, and passive deposition samples done concurrently by WSU and UW research teams. The study included an application using a drift retardant, to measure the effect on surface deposition. The results of this study are being compared to the AgDrift model developed by the spray drift task force, and also with the FDM model from US EPA.  A manuscript in preparation describes the study and the AG Drift model results, and findings will be presented at the Conference on Health & Safety in Western Agriculture: Research to Practice September 20-22, 2006 in Asilomar, California.
Community inhalation exposures to methamidophos off sprayed potato fields in Washington State: Consideration of volatilization and meteorological conditions.
We used historical meteorological data along with FDM model simulations for different meteorological conditions to put case study and measurements as presented by Ramaprasad et al (Society for Risk Analysis, 2004) in climatological perspective for the area to estimate how ‘typical’ our calculated risk values are. Further analysis of the volatilization data and spray particle data were conducted in 2005-6, revealing that chronic and sub-chronic risk estimates could exceed acceptable limits under adverse weather conditions. Acute risks calculated for children in the study are well within an acceptable margin for the meteorological conditions in that area. A publication (Ramaprassad, 2004) described the volatilization model, and manuscript in preparation describes the risk assessment work; the findings were also presented at the NW conference on sustainable agriculture in Richland WA in the spring of 2006.
Construction of a GIS dataset with estimates of pesticide use in Washington State.
We have built upon existing GIS data of pesticide use in Yakima County collected by a previous student working on this project.  The dataset describes crop cover and pesticide use near selected residential farm locations in Yakima. We have developed the map layers (shape files) for field crops and pesticide usage for all of Washington State in order to build a crop and land-use classification model. The thirty-five crop layer maps developed this past year were made according to the 2003-05 Washington State Department of Agriculture Crop Distribution database. The pesticide shape files were created for azinphosmethyl, carbaryl, chlorpyrifos, dimethoate, imadicloprid, and malathion.  These shape files show the location of fields and pesticide usage is estimated based on extension service recommendations for each crop. The dataset will be used to estimate the proximity of communities with children to areas with elevated pesticide usage.
SIGNIFICANCE: Washington aerial spray study--Modeling pesticide spray drift deposition from an aerial application: Our calibration of the model to samplers located in the areas of interest allows it to serve as a potential tool for conducting exposure assessment, despite the limitations of FDM in modeling a liquid aerosol.
Community inhalation exposures to methamidophos off sprayed potato fields in Washington State: Consideration of volatilization and meteorological conditions. This work demonstrates the importance of meteorological conditions and vapor phase emissions for providing a context for assessing children’s exposure and risk from spray drift.

Future Activities:

Washington aerial spray study: Modeling pesticide spray drift deposition from an aerial application.   The final manuscript preparation and submission for this study will be conducted this coming year.
Observations and modeling of airborne spray aerosols and deposition parameters.  Ming Tsai will complete the spray drift deposition model with selection, calibration, and prediction for this aerial spray event using the Fugitive Dust Model previously used in the Washington aerial spray study.  The real-time Lidar and deposition and air samples will be used along with the real-time meteorological inputs.
Previously we had planned to conduct a study of aerial spraying of cotton sites in lower Rio Grande Valley in South Texas.  As discussed above we have modified this plan because our major collaborator, Dr Elgethun, is relocating to a job in Idaho. We plan to conduct a study of aerial OP application in potatoes in the coming year. This study will parallel the previous work on aerial applications in a new site, with different climate that favors natural ventilation and low evaporation and volatization of pesticides. 
Construction of a GIS dataset with estimates of pesticide use in Washington State. This work will continue to provide baseline geo-referenced estimates of pesticide use for the study county, and, when coupled with our current modeling work, also can estimate air and aerosol emission factors for the county with our dispersion models. The emission data also will be linked with census population data to locate areas with high potential for human (especially children’s) exposures. In future years a follow-up survey of farmers in the area can be used to determine usage patterns for each crop and to examine the potential influence of different crop management practices such as integrated pest management. Finally we can use our existing urine and house dust data in 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).  We plan to apply our volatilization model to the GIS data in an effort to assess inhalation exposures. A pilot study is underway to determine if community level vapor phase pesticide levels can be measured and used to validate the model results.
Washington airblast spray study.  During the next reporting period, we will prepare for the Washington state airblast spray study which is scheduled for year four (06-07). We will extend the proximity studies to investigate potential drift from air blast applications.  Air blast applications are less widely studied and have potential for a more diffuse distribution of chemicals compared to aerial spray. This year we will assess potential study sites in the Wenatchee area of Washington State where tree fruit, in particular apples, are the primary crop. We will identify residential communities within the region that may be impacted by multiple spray events at different sites over multiple days due to the range of farm size that surrounds the residential areas. Pesticide dispersion will be impacted by the meteorological conditions and the local terrain.  As we will model aerosol and vapor phase dispersion in terms of impact on residential areas; sampling also will take place at potential community receptor sites including schools and playgrounds.

Journal Articles on this Report : 3 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 105 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 Tsai M-Y, Elgethun K, Ramaprasad J, Yost MG, Felsot AS, Hebert VR, Fenske RA. The Washington aerial spray drift study: modeling pesticide spray drift deposition from an aerial application. Atmospheric Environment 2005;39(33):6194-6203. R831709 (2005)
    R831709 (2007)
    R831709C004 (2005)
    R831709C004 (2006)
  • Full-text: ScienceDirect-Full Text HTML
  • Abstract: ScienceDirect
  • Other: ScienceDirect-Full Text PDF
  • 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
    2007 Progress Report

    Main Center Abstract and Reports:

    R831709    University of Washington

    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