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RESULTS FROM THE AHS PESTICIDE EXPOSURE STUDY
Citation:
Thomas, K W., S. M. Gordon, M. Jones, J. Raymer, C. Lynch, C. Knott, D. P. Sandler, M. Dosemeci, AND M. Alavanja. RESULTS FROM THE AHS PESTICIDE EXPOSURE STUDY. Presented at AHS National Advisory Panel Meeting, Bethesda, MD, February 26-27, 2004.
Impact/Purpose:
The primary goal of the AHS Pesticide Exposure Study (AHS/PES) is to measure exposure to applied pesticides for a subset of the cohort of private pesticide applicators and to provide data to evaluate exposure algorithms developed for exposure classification in the study cohort.
Description:
The Agricultural Health Study/Pesticide Exposure Study (AHS/PES) measured exposures resulting from agricultural use of 2,4-D and chlorpyrifos for a subset of applicators in the AHS cohort. Through on-farm measurements and observations, data collected in the exposure study will be used to examine the range of applicator exposures, evaluate AHS exposure classification procedures, identify key exposure factors, and assess whether farm applicator family members are exposed to the applied target pesticides.
A telephone screening process identified private pesticide applicators in the AHS cohort living in selected counties in Iowa and North Carolina that would be eligible for recruitment. Eligibility required the planned use of a target chemical in one of eight different exposure scenarios that were based on combinations of three application methods (broadcast spray, hand spray, banded/in-furrow) and two types of protective equipment (protective gloves and enclosed tractor cabs). Spouses and children living with the applicator were asked to participate. Monitoring was performed around one day of pesticide mixing, loading, and application (MLA). Research staff observed and recorded information about the pesticide MLA activities. Two questionnaires were administered during the monitoring period to collect information on pesticide use, work practices, hygiene, and other activity information. The full AHS Phase II CATI was administered to the exposure study participants several months after the monitoring visit.
One pre-application and two post-application urine samples were collected from participating pesticide applicators. In addition, post-application composite 24-h urine samples were collected from applicators over an additional four days for 48 of the 108 monitored applications. Dermal patch samples were collected by placing 10 cellulose or gauze patches on the applicator's chest, back, upper arms, forearms, upper legs, and lower legs. The surface area of each patch was sized proportionately to the body area it represented. Patches were combined into one or two samples for extraction. Hand wipe samples were collected with isopropanol-wetted polyurethane swabs from 12 defined areas (3-cm2 each) on each hand. Air samples were collected using a small battery-operated pump and an OVS sampling cartridge containing XAD-2 sorbent. Participating spouses and children provided first-morning void urine samples on the day of the observed MLA activity and again two days later. All samples were solvent extracted and analyzed by gas chromatography/mass spectrometry.
A total of 108 monitoring visits were completed at 84 different farms during the planting and growing seasons from 2000 to 2002. Applicators on 20 of those farms were monitored a second time, and four applicators were monitored a third time. Spouses provided urine samples during 49 monitoring visits and child urine samples were collected during 12 visits. An additional nine children participated by completing only the activity questionnaire. There were 84 monitoring visits in Iowa and 24 monitoring visits in North Carolina. Products containing 2,4-D or chlorpyrifos were used 89 and 18 times, respectively, in the monitored applications. One North Carolina applicator used only an atrazine product during the monitoring visit; the dermal and air samples were analyzed for this participant but the urine samples were not. The number of monitored applications in the eight exposure scenario strata ranged from 6 to 22.
All monitored uses of 2,4-D involved liquid product formulations that were applied by broadcast or hand-held sprayers. The 2,4-D concentration in these applicators' pre-application urine samples ranged from <1 to 870 ug/L, while the concentration in the first post-application urine samples ranged from 1.6 to 1000 ug/L. Estimated hand loadings for these applicators at the end of the observed pesticide uses ranged from <10 to 25,000 ug and estimated body loadings ranged from <40 to 880,000 ug. Personal air 2,4-D concentrations ranged from <0.5 to 14 ug/m3. Liquid formulations were used for five of the chlorpyrifos applications while the remaining 13 uses were banded or in-furrow applications of a granular product. The concentration of the chlorpyrifos metabolite 3,5,6-trichloro-2-pyridinol (TCP) in these applicators' pre-application urine samples ranged from 2.1 to 62 ug/L, while the concentration in the first post-application urine samples ranged from 2.5 to 80 ug/L. Estimated hand loadings for these applicators at the end of the observed pesticide uses ranged from <10 to 930 ug and estimated body loadings ranged from <40 to 5800 ug. Personal air chlorpyrifos concentrations ranged from <0.1 to 2.0 ug/m3.
Data review and analysis for this project is ongoing. An overview of the urinary biomarker, dermal, and air concentration measurement results, along with relationships between different measures, will be presented in the meeting poster. Differences in exposure measurements across the eight exposure scenarios will be described to the extent that analyses have been completed. Urinary biomarker measurement results will be presented for the spouses and children.
Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.