2000 Progress Report: Pesticide Exposure Pathways Research Project

EPA Grant Number: R826886C004
Subproject: this is subproject number 004 , established and managed by the Center Director under grant R826886
(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: August 1, 1998 through December 31, 2003
Project Period Covered by this Report: August 1, 1999 through July 31,2000
Project Amount: Refer to main center abstract for funding details.
RFA: Centers for Children's Environmental Health and Disease Prevention Research (1998) RFA Text |  Recipients Lists
Research Category: Children's Health , Health Effects , Health


The long-term objectives of this project are to: prioritize efforts that prevent childhood pesticide-associated illness; estimate the relative contribution of major pesticide exposure pathways to farmworker children exposure; expedite the development of effective intervention strategies; and develop model intervention strategies for reducing pesticide exposure.

The specific aims are to:

  • Quantify spatial and temporal variability in pesticide residues in and around residences of farmworker children, including quantifying the impact of spray drift during and after pesticide application;
  • Characterize child activities during periods of residential pesticide contamination and during periods when children have the opportunity to enter recently pesticide-treated areas;
  • Quantify transfer of pesticides from workplace to residence by farmworkers and subsequent exposure of farmworker children;
  • Develop a source attribution model for the major pesticide exposure pathways based on environmental measurements, child activities, and biological measures of exposure;
  • Develop specific recommendations for interventions designed to reduce pesticide exposure in farmworker children.

Progress Summary:

During the second year, we have continued to develop methods needed for the multi-pathway exposure assessment of children in agricultural communities. Progress has been made in three areas: development of a LIght Detection And Ranging (LIDAR) system for evaluating spray drift, acquisition and testing of global positioning system (GPS) units for tracking children’s behavior, and design of a field sampling study to quantify pesticide drift. Each of these areas is discussed in detail below. Additionally, the Department of Environmental Health (DEH) Laboratory has completed development of new methods for analysis of pesticides in housedust.

LIDAR Development

The LIDAR instrument described in the original proposal was tested to determine its range-finding capabilities in an agricultural region of the state in Year 1. The spray plume was detected by the unit, but signal strength was deemed inadequate. It was concluded that a stronger laser would be required. University of Washington investigators are now exploring the possibility of purchasing a new laser. We also concluded that a scanning apparatus would optimize the use of this instrument. In Year 2 we have continued with development efforts to improve the LIDAR instrumentation for the project. The scanner has been constructed and fitted to the instrument. The instrument will undergo final integration of data collection software with the motion control system in September through a contract with ORCA Photonic, the instrument manufacturer. We have conducted further evaluation of field data collected over several hours during an orchard airblast application. Range resolved data were obtained along several lines-of-sight directed through the spray plume. A mechanical shutter placed in the laser transmitter path allowed us to collect an ambient light background for each path. After subtracting the background the signal was range corrected using an inverse square law and fixed topographic landmarks to provide a ground reference. Figure 1 shows an example of LIDAR backscatter data collected through a plume at a range of about 350 m from the instrument. The large peak corresponds to the main (visible) aerosol cloud, followed by a smaller peak in a drift region extending about 100 m downwind. The field data indicate that the current system is quite capable of tracking plumes and spray drift at ranges < 1 km, but at longer ranges it is likely that only the main plume would be detected. Although the 1 km range will be adequate for initial field results, it may limit the ability to study multiple sources. We are exploring options for increasing the laser power and detector sensitivity, although daylight operation limits the ability to gain much improvement from the detector alone. Ming Tsai, formerly a Ph.D. candidate in the Department of Civil Engineering, has enrolled as a Ph.D. student in Environmental Health. He is working with Dr. Yost to develop the hardware and software components of the LIDAR instrument.

Figure 1.

Global Positioning System Component

In Year 1 feasibility studies were conducted with commercially available GPS units. In Year 2 we have purchased three customized GPS units from Entertech Corporation in Campbell, California. Kai Elgethun, a Ph.D. student working on this project, traveled to Entertech in July to pick up the instruments and receive detailed instructions on the hardware and software operations. We have evaluated the capabilities of these units, and report the following:

  • The recording frequency is variable; the shortest increment is 1 second.
  • Mounting the unit on the shoulder seems to provide adequate reception.
  • Foliage and heavy clothing do not seem to block the signal.
  • The instrument can be interfaced with relevant databases for corrections via the internet.

The units have undergone preliminary field testing, and demonstrate excellent accuracy; their performance is substantially better than the commercial units tested last year. We intend to conduct extended testing of these units with children in September and October, including testing in agricultural regions in central Washington State.

Drift Sampling Component

During Year 1 we completed a review of the pesticide drift literature, and contacted experts in this field. In Year 2 we identified a major industry report produced by the Spray Drift Task Force. This task force has been working with the U.S. Environmental Protection Agency (EPA) to establish a scientific basis for human ecological risk assessments related to agricultural spraying. We are using material from this report in the development of our drift sampling strategies. We have also determined that the most feasible and economical means of studying spray drift for the next year is with a fluorescent surrogate. We intend to conduct controlled field spraying with the fluorescent whitening agent, Uvitex OB™, during September and October of this year. This fluorescent compound has been used extensively to evaluate occupational pesticide exposures during applications. It is relatively simple to analyze via spectrofluorometry, so a large number of samples can be gathered in these field studies. We intend to use high volume air samplers and deposition coupons to collect spray residues for 2-4 hours after an application event and to map the distribution of these residues. These data will allow calibration of the LIDAR system.

Future Activities:

In Year 3 we intend to sample a minimum of 20 children living in proximity to treated orchards. These studies will quantify spray drift patterns, children’s locations, and pesticide residue levels in the child’s environment. Families will be recruited for this study in the winter 2001, and sampling will occur in the spring and summer 2001. Laboratory analysis of residue samples will be conducted in the summer and fall 2001.

Journal Articles:

No journal articles submitted with this report: View all 15 publications for this subproject

Supplemental Keywords:

children, health, pesticide, exposure, neurodevelopment, organophosphates., RFA, Health, Scientific Discipline, Toxics, Environmental Chemistry, Health Risk Assessment, pesticides, Risk Assessments, Biochemistry, Children's Health, health effects, pesticide exposure, organophosphates, biological response, environmental risks, neurodevelopment, children, Human Health Risk Assessment, neurotoxicity, assessment of exposure, susceptibility, toxicity, paraoxonase polymorphism, human exposure, environmental health hazard, growth & development, neurological development

Relevant Websites:

http://depts.washington.edu/chc/ Exit

Progress and Final Reports:

Original Abstract
  • 1999
  • 2001 Progress Report
  • 2002 Progress Report
  • 2003
  • Final

  • Main Center Abstract and Reports:

    R826886    University of Washington

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R826886C001 Molecular Mechanisms of Pesticide-Induced Developmental Toxicity
    R826886C002 Genetic Susceptibility to Pesticides (Paraoxonase Polymorphism or PON1 Study)
    R826886C003 Community-Based Participatory Research Project
    R826886C004 Pesticide Exposure Pathways Research Project