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MODELING OF MACROSCALE AGRICULTURAL ELEMENTS IN PESTICIDE EXPOSURE
Citation:
Hern, S C., D. Bronson, D. Osgood, C. Rosales, AND M. K. O'Rourke. MODELING OF MACROSCALE AGRICULTURAL ELEMENTS IN PESTICIDE EXPOSURE. Presented at 11th Annual Meeting of the International Society of Exposure Analysis, Charleston, SC, November 4-8, 2001.
Impact/Purpose:
The overall purpose of the Pesticides in Young Children - Border States program is to describe the relationship of health outcomes in children along the United States and Mexico border to repeated pesticide exposures via multiple sources and pathways. The current effort will analyze the data available from Phase I and II studies to identify and address critical questions about three major areas: (1) the applicability of pesticide biomarkers for use as markers of exposure, (2) the predictive capability of quesionnaires for estimating exposure, and (3) identification of the most appropriate cohorts to be included in the Phase IIIb studies.
Description:
Yuma County, Arizona, is the site of year around agriculture. To understand the role of agricultural pesticide exposures experienced by children, urinary metabolite concentrations were compared with agricultural use of pesticides. The urinary metabolite and household data were taken from the Children's Pesticide Study in Yuma County. The regional pesticide application data were obtained from the Arizona Department of Agriculture 1080 form. Data were examined using geospatial analysis (ArcInfo).
Chlorpyrifos, an organophosphate insecticide used in conjunction with permethrin on broccoli, can be specifically detected by the presence of a metabolite, 3,5,6-trichloro-2-pyridinol (TCPY), in urine. Chlorpyrifos exposure (TCPY) was compared with macroscale pesticide use. In anticipation of observing seasonal differentiation, the data were examined for seasonal trends. Chlorpyrifos exhibited a bimodal trend with peaks in the spring and fall. A preliminary linear regression examined monthly levels of agricultural chlorpyrifos application and TCPY observed in urine samples. The association was not significant (p = 0.669). An examination of creatinine-adjusted dimethylphosphate (DMP) levels in the urine was significantly correlated to agricultural use of dimethoate, methidathion, and malathion (p = 0.002), but this significance is being driven by a single observation. Other variables must therefore play an important part in pesticide exposure. The pesticide exposure potential (PEP) will be an aggregate of macroscale agricultural exposure, and microscale exposures integrated through the child, and represented by the TCPY measurement. Microscale exposures include paraoccupational exposure and the use of pesticides in and around the home. Better assessment of the macroscale agricultural exposure involved creating a model incorporating the distance between households and the point of pesticide application, a host of weather variables including wind direction and temperature, and environmental half-life measures for the pesticides. This model was then used to predict metabolite levels in a spatial array of regional urine samples taken by the Centers for Disease Control and Prevention.
This research was funded by the United States Environmental Protection Agency (#825169) and ADHS (#161037). This abstract has been subjected to Agency review and approved for presentation.