Academic journal article Environmental Health Perspectives

Biologic Monitoring to Characterize Organophosphorus Pesticide Exposure among Children and Workers: An Analysis of Recent Studies in Washington State

Academic journal article Environmental Health Perspectives

Biologic Monitoring to Characterize Organophosphorus Pesticide Exposure among Children and Workers: An Analysis of Recent Studies in Washington State

Article excerpt

We examined findings from five organophosphorus pesticide biomonitoring studies conducted in Washington State between 1994 and 1999. We compared urinary dimethylthiophosphate (DMTP) concentrations for all study groups and composite dimethyl alkylphosphate (DMAP) concentrations for selected groups. Children of pesticide applicators had substantially higher metabolite levels than did Seattle children and farmworker children (median DMTP, 25 [micro]g/L; p < 0.0001). Metabolite levels of children living in agricultural communities were elevated during periods of crop spraying. Median DMTP concentrations for Seattle children and farmworker children did not differ significantly (6.1 and 5.8 [micro]g/L DMTP, respectively; p = 0.73); however, the DMAP concentrations were higher for Seattle children than for farmworker children (117 and 87 nmol/L DMAP, respectively; p = 0.007). DMTP concentrations of U.S. children 6-11 years of age (1999-2000 National Health and Nutrition Examination Survey population) were higher than those of Seattle children and farmworker children at the 75th, 90th, and 95th percentiles. DMTP concentrations for workers actively engaged in apple thinning were 50 times higher than DMTP concentrations for farmworkers sampled outside of peak exposure periods. We conclude that workers who have direct contact with pesticides should continue to be the focus of public health interventions and that elevated child exposures in agricultural communities may occur during active crop-spraying periods and from living with a pesticide applicator. Timing of sample collection is critical for the proper interpretation of pesticide biomarkers excreted relatively soon after exposure. We surmise that differences in dietary exposure can explain the similar exposures observed among farmworker children, children living in the Seattle metropolitan area, and children sampled nationally. Key words: agricultural communities, agricultural workers, biologic monitoring, children, dialkylphosphates, organophosphorus pesticides, pesticide exposure. Environ Health Perspect 113:1651-1657 (2005). doi:10.1289/ehp.8022 available via http://dx.doi.org/ [Online 6 July 2005]

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Children may experience greater risks from pesticide exposures than adults because of behavioral, dietary, and physiologic characteristics associated with development (National Research Council 1993). University of Washington researchers began an investigation of children's exposure to pesticides in 1991, with particular emphasis on organophosphorus (OP) pesticide exposures of presumed high-risk populations, such as children of pesticide applicators, children of farmworkers, and children living in agricultural regions with substantial agricultural pesticide use (Curl et al. 2002; Fenske et al. 2002; Koch et al. 2002; Loewenherz et al. 1997; Lu et al. 2000, 2001; Simcox et al. 1999). These studies have suggested that children with parents who apply pesticides in agriculture and who live in agricultural areas during active crop spraying receive higher OP pesticide exposure than do other children.

Each of these studies has employed biologic monitoring of urinary dialkylphosphate (DAP) metabolites to yield information on OP pesticide exposure. Biologic monitoring is a valuable tool in exposure assessment, allowing for integrated measurement of exposure from all pathways and routes. Biologic monitoring has been used effectively to evaluate exposures to populations across studies and across time (Barr et al. 2004a; National Research Council 1991). This approach has been used in many regional studies to determine OP pesticide exposures among young children (Adgate et al. 2001; Aprea et al. 2000; Heudorf and Angerer 2001; Heudorf et al. 2004; Mills and Zahm 2001; Morgan et al. 2005; Royster et al. 2002; Shalat et al. 2003).

More than 30 OP pesticides are registered for use in Washington State, and many of these pesticides do not have urinary metabolites that can be considered selective. …

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