2002 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, 2001 through July 31,2002
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 specific aims of this study are to: (1) continue the development of the use of global positioning system (GPS) and the LIDAR for the purpose of pesticide exposure assessment; and (2) design and conduct an exposure assessment study in which the effects of agricultural spray to children who live nearby the farmland will be studied.

Progress Summary:

Global Positioning System Study

The pilot study of 11 Seattle children wearing a GPS personal acquisition logger (GPS-PAL) was completed in the spring of 2001. This study is summarized in the accepted manuscript listed below and was presented at two meetings in 2001. Kai Elgethun, lead researcher on the GPS component, successfully presented his dissertation proposal in February 2002 and advanced to Ph.D. candidacy. Two field studies that incorporate the GPS-PAL will be conducted in 2002. The first study compares GPS-PAL time-location data to parent-reported data recorded on the timeline used in the National Human Exposure Assessment Survey (NHEXAS) studies. Our hypothesis that the GPS-PAL is significantly more accurate than parent-reported data on child time-location will be tested in this study. The second study integrates GPS-PAL, electronic activity monitoring, and observational behavior monitoring into a sampling plan to characterize children’s exposure to pesticide spray drift. The goal is to connect duration and frequency of contact time with airborne pesticide and pesticide-loaded surface concentrations during and after the spray event. This will afford a particularly refined exposure profile for this population. This study will test our hypothesis that children living proximal to agricultural fields receive significant exposure to organophosphate (OP) pesticides during spray events and receive variable exposure depending on where they go and how active they are during this period. We have secured the participation of the farmer and the community members to ensure the success of this study. Potato fields surrounding the subjects’ community will be sprayed with an OP pesticide via fixed-wing aircraft at the end of July. Further details of this study are presented in the Study Design and Timeline section of this report. The GPS and activity monitoring data from the drift study will be presented this August at an international meeting.


As reported last year, Orcaphotonics’s LRS-50 LIDAR has been retrofitted with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser with appropriate changes to the optical system to accommodate the change from an infrared (IR) to UV laser light source. We have conducted two field studies with the new instrument. Following the first field study to eastern Washington to monitor a pesticide airblast application, we noted the need for both studies of known aerosols as well as further software and hardware modifications. Known aerosol studies are important to quantitatively interpret our LIDAR signal and allow us to assess the performance of our instrument. We have completed a study of the pacific marine aerosol at Westport, Washington, and are currently analyzing the data. Instrument modifications included basic custom software improvements to facilitate data export and adequate logging of LIDAR position and hardware optimization consisting of replacing a low quality UV mirror and performing laser alignment optimization for our target range. Some software improvements have been made, but data export continues to be cumbersome.

The LIDAR monitoring of the Pacific marine aerosol at Westport, Washington, in late March has provided us with data that will allow us to calibrate our LIDAR to a known aerosol. Essential to LIDAR calibration is the knowledge of an aerosol’s optical properties and size distribution; therefore, working with the marine aerosol allows us to focus on a well-characterized single source aerosol. Additionally, with the Pacific Ocean as a continuous generator of aerosols, we were able to conduct long-term monitoring of a relatively constant source. A critical finding of this trip was that the current oscilloscope card of our LIDAR system is unable to capture the fine features of surf-generated aerosol clouds that a good digital oscilloscope can track. For the LIDAR to provide good measurements of the parameters to be used with a Gaussian dispersion model of spray drift, accurate measurement of plume width and height downstream are essential. Hence, it is essential that a faster oscilloscope card replace the current one. The LIDAR system is currently able to see the marine aerosol up to about 2 km, this range can be increased by upgrading the oscilloscope card.

We are currently planning a third field study to monitor a controlled release of a non-toxic diatomaceous earth vehicle mixed with water to simulate an actual pesticide release. This controlled experiment will allow us to characterize a pesticide aerosol size distribution by using cascade impactors, and we will also be able to determine the approximate optical properties of pesticide aerosols. From our two field studies, in addition to in-house studies, the current LIDAR system needs some additional enhancements to be fully capable of providing measurements of pesticide spray drift parameters. The main hardware improvement is an upgrade of the oscilloscope card. Software improvements are also essential for convenient use of the instrument. These improvements are underway, and a better system should be ready for deployment in time for the spray drift study in late July/early August 2002.

Spray Drift Study

In October 2001, we had learned that the field around the community that we had targeted for recruiting would not be treated with pesticides in which we are interested. We then began to talk to the company who owns most of the lands in the area for identifying another field which will be treated with OP pesticides in the 2002 growth season. This le d to the changes of our study protocols and therefore approval from the University of Washington (UW) Human Subjects committee is needed. In February, we identified a potential study community in eastern Washington and met with community leaders and farm operators to discuss community participation in the study. In March 2002, we requested and received Human Subjects’ approval for modifications to our field sampling procedures. Modifications included the collection of outdoor air , surface-wipe, and hand-wipe samples, in addition to the collection of indoor air, housedust, and urine samples. We also received approval to collect information regarding child activity level, hand-to-mouth behavior, and home pesticide use. Researchers were given approval to collect child activity data using an activity monitor watch during baseline and post-spray sampling periods. Information regarding child behavior and pesticide sources are to be collected through observations and interviews. Additional approved modifications in the study design include changes in the age of child participants and recruitment methods. We increased our recruitment age from 1 to 5 years old to 2 to 12 years old because older children are likely to exhibit different play patterns than younger children. We believe that this difference in play patterns may have an effect on exposure levels.

In April we received Human Subjects’ approval for our recruitment methods and material. Initially we had planned to train bilingual staff to approach families at their residences. However, in past studies, we have found that this approach is not very effective, as it is difficult to contact farm workers during the spring planting season due to their long work days. Therefore, we held an evening informational meeting in the study community. We invited all community members to attend regardless of eligibility and handed out recruitment materials at the meeting. Three bilingual UW staff were present to explain the study purpose and to answer any questions. We successfully enrolled six families and 11 children for participation in the drift study at that time.

Collaboration with Food and Environmental Quality Laboratory at Washington State University

In early February, we established a collaboration with Dr. Alan Felsot and Dr. Vince Hebert of the Food and Environmental Quality Laboratory (FEQL) at Washington State University (WSU) in Richland, Washington. Dr. Felsot and Dr. Hebert both have extensive experience in conducting pesticide drift field studies. Because of the proximity to the field, FEQL at WSU will provide us with a field-based laboratory, which is very convenient for conducting field sampling of this nature and is essential for sample preparation and field quality assurance/quality control (QA/QC) procedures.

Since we are studying a new OP pesticide, we have established that the FEQL will provide UW researchers with analytical support for quantifying methamidophos residues in/on air sampling adsorbants, drift cards, housedust and surface and hand wipes. The FEQL will also quantify the principle metabolite, OS-dimethyl phosphorothioate (DMPT), in urine samples taken from children over a multiple-day exposure period. The FEQL will perform methamidophos analysis using solvent extraction procedures that closely follow U.S. Environmental Protection Agency (EPA) enforcement methods and will quantify parent residues for all matrices by gas chromatography (GC) with pulsed flame photometric detection. If needed, the FEQL will employ GC/mass spectroscopy (GC/MS) to confirm results. After a method has been established for each matrix, the FEQL will perform a validation study prior to sample analysis. The method will be considered validated if recoveries fall within 70 – 120 percent for the analyte(s) with a combined coefficient of variation < 20 percent. After the validation exercise, residue analyses for the parent or DMPT will be conducted on residue samples with appropriate quality control samples. A report will be generated that includes methods, validation results, percent recoveries, storage stability, calculations, and residue results for parent and metabolites. At this point, UW researchers and the FEQL have successfully developed field sampling strategies, sampling techniques, and standard operating procedures for the drift study. The FEQL has also completed recovery and breakthrough evaluations for the selected sampling and trapping media (polyurethane foam [PUF] and wipes). A method for quantifying DMPT in urine is currently under development and will likely follow existing methods that isolate the alkyl phosphates from urine, followed by derivitization, and quantification by GC with MS.

Baseline Sampling

We conducted the baseline sampling during the first week of June. Baseline sampling included collection of housedust, surface wipe, toy wipe, hand wipe, and spot urine samples. These samples were transported to the FEQL in Richland, Washington, where they will be analyzed for methamidophos residues. We will collect baseline indoor and outdoor air concentrations in mid-July prior to the first aerial application of methamidophos.

Future Activities:

We have spoken to the field operations manager at our study site and have established that the first seasonal application of methamidophos in the fields surrounding the site will occur in late July. This application will be aerial. We will collect indoor and outdoor air, deposition, and 24-hour urine samples during and prior to the spray event. We will also collect housedust and wipe samples prior to the spray event. We anticipate that all field sampling activities will be completed and laboratory analysis will commence in late July/early August.

Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other subproject views: All 15 publications 9 publications in selected types All 9 journal articles
Other center views: All 87 publications 77 publications in selected types All 73 journal articles
Type Citation Sub Project Document Sources
Journal Article Curl CL, Fenske RA, Kissel JC, Shirai JH, Moate TF, Griffith W, Coronado G, Thompson B. Evaluation of take-home organophosphorus pesticide exposure among agricultural workers and their children. Environmental Health Perspectives 2002;110(12):A787-A792. R826886 (2000)
R826886C003 (2001)
R826886C003 (2002)
R826886C004 (2001)
R826886C004 (2002)
  • Full-text from PubMed
  • Abstract from PubMed
  • Associated PubMed link
  • Journal Article Elgethun K, Fenske RA, Yost MG, Palcisko GJ. Time-location analysis for exposure assessment studies of children using a novel global positioning system instrument. Environmental Health Perspectives 2003;111(1):115-122. R826886 (2000)
    R826886C004 (2002)
    R831709 (2005)
    R831709 (2007)
  • Full-text from PubMed
  • Abstract from PubMed
  • Associated PubMed link
  • Journal Article Moate TF, Furia M, Curl C, Muniz JF, Yu J, Fenske RA. Size exclusion chromatographic cleanup for GC/MS determination of organophosphorus pesticide residues in household and vehicle dust. Journal of the AOAC International 2002;85(1):36-43. R826886 (2000)
    R826886C004 (2001)
    R826886C004 (2002)
  • Abstract from PubMed
  • Abstract: Ingenta-Abstract
  • Journal Article Thompson B, Coronado G, Puschel K, Allen E. Identifying constituents to participate in a project to control pesticide exposure in children of farmworkers. Environmental Health Perspectives 2001;109(Suppl 3):443-448. R826886 (2000)
    R826886C003 (2001)
    R826886C003 (2002)
    R826886C004 (2001)
    R826886C004 (2002)
  • Full-text from PubMed
  • Abstract from PubMed
  • Associated PubMed link
  • Supplemental Keywords:

     , 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
  • 2000 Progress Report
  • 2001 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