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ASSESSING EXPOSURE CLASSIFICATION IN THE AGRICULTURAL HEALTH STUDY
Citation:
Thomas, K W., M. Dosemeci, J. Coble, G Chapa, C Croghan, P A. Jones, J. A. Hoppin, D. P. Sandler, A. Blair, AND M. Alavanja. ASSESSING EXPOSURE CLASSIFICATION IN THE AGRICULTURAL HEALTH STUDY. Presented at Industry Farm Family Study Task Force Meeting, Philadelphia, PA, October 19, 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 (AHS) is a prospective epidemiologic study examining cancer and non-cancer health outcomes for over 55,000 pesticide applicators and 34,000 spouses in Iowa and North Carolina. Questionnaires were used to collect information about the use of specific agricultural pesticides, work practices, and personal protective equipment. Algorithms were developed to calculate exposure intensity scores for individual applicators using literature-derived data for several important exposure factors. The AHS Pesticide Exposure Study was designed to measure applicator exposures to 2,4-D or chlorpyrifos to assess the exposure intensity algorithms. Applicators were selected into one of eight exposure scenarios based on their use of specific application methods and personal protective equipment. Dermal patch, hand wipe, and personal air samples were collected during pesticide mixing, loading, and application activities on one day. Urinary biomarker levels were measured in pre-and post-application samples. Observations and questionnaires provided information about activities that may affect exposure. A total of 108 monitoring visits were completed at 84 farms. Geometric means for the eight scenarios ranged from 7 to 70 µg/L in post application urine, 12 to 2200 µg for hand loading, 180 to 21000 µg for body loading, and 0.2 to 1.5 µg/m3 in personal air. Post-application urine concentrations and exposure intensity scores derived from observations of work activities were significantly correlated for applications of liquid 2,4-D products (Spearman r = 0.40, p < 0.0001) and applications of liquid chlorpyrifos products ( r = 0.97, p = 0.0048) but not for applications of granular chlorpyrifos products. Adjustment for the amount of active ingredient used increased the correlation between post application urine levels and exposure intensity scores for 2,4-D (r = 0.63, p < 0.0001). Dermal loadings were also significantly correlated with exposure intensity scores derived from observed work practices. In a preliminary analysis, exposure intensity scores derived from work practice information from a questionnaire completed by the pesticide applicator were similar to those derived from observations (r2 = 0.80). Correlations between exposure measures and the questionnaire-derived exposure intensity scores were similar to those from observer-derived scores.
Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.