| Variation in Organophosphate Pesticide Metabolites in Urine of Children Living in Agricultural Communities William E. Lambert,1 Michael Lasarev,1 Juan Muniz,2 Jennifer Scherer,1 Joan Rothlein,1 Juanita Santana,3 and Linda McCauley2 1Center for Research on Occupational and Environmental Toxicology, Oregon Health and Science University, Portland, Oregon, USA; 2School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania, USA; 3Oregon Child Development Coalition, Wilsonville, Oregon, USA Abstract
Children of migrant farmworkers are at increased risk of exposure to organophosphate pesticides because of "carry-home" transport processes and residential location. Although this at-risk status is generally recognized, few available reports describe the extent of this exposure among agricultural communities. We quantified dialkyl phosphate (DAP) levels in serial samples of urine from 176 children, 2-6 years of age, in three Oregon communities hosting differing agricultural industries: pears, cherries, and fruit berries. Up to three spot samples of urine were collected from children at the beginning, mid-point, and end of their parents' work seasons. The median levels of dimethylthiophosphate (DMTP) , the most commonly detected metabolite, was significantly higher in urine samples from children in each of the three agricultural communities (17.5, 19.0, and 41.0 ng/mL) relative to a reference group of children who lived in an urban community and whose parents did not work in agriculture (6.5 ng/mL ; Kruskal-Wallis, p < 0.001) . After controlling for age, sex, and weight, the median level of DMTP in children in the pear community was 1.92 times higher than the level in children of the berry community [95% confidence interval (CI) , 1.14-3.23] and 1.75 times higher than the level in children of the cherry community (95% CI, 0.95-3.23) . We observed increasing levels of DMTP across the work season only within the berry community. Levels decreased in the cherry community and remained constant in the pear community. Substantial temporal variation within the children followed demonstrates the need for multiple urine samples to most accurately characterize longer term and/or cumulative exposure. The observed variability in urinary DAP levels, between communities and over time, could be attributed to the types and amounts of organophosphate pesticides used, the timing of applications and degradation of residues in the environment, work operations and hygiene practices, the proximity of housing to orchards and fields, or the movement of these working families. Additional studies of variation in pesticide exposure across agricultural regions are needed. Key words: agriculture, children, farmworkers, pesticides. Environ Health Perspect 113: 504-508 (2005) . doi:10.1289/ehp.6890 available via http://dx.doi.org/ [Online 10 January 2005]
Address correspondence to L. McCauley, FAAN, Nursing Education Building, 420 Guardian Dr., University of Pennsylvania, Philadelphia, PA 19104-6096 USA. Telephone: (215) 898-9160. Fax: (215) 898-3056. E-mail: lmccaule@nursing.upenn.edu We thank the children and the staff of the Migrant Head Start centers who participated in this study. We also acknowledge the data collection and technical contributions of R. Travers and J. Phillips of the Oregon Child Development Coalition, and those of G. Higgins, E. Mahoney, L. Pham, J. Richman, and K. Wax of the Center for Research on Occupational and Environmental Toxicology at Oregon Health and Science University. This work was supported by the National Institute of Environmental Health Sciences (NIEHS) through a Community-Based Prevention/Intervention Research Program grant (R01 ES08707, L.M., Principal Investigator) . Its contents are solely the responsibility of the authors and do not necessarily represent the official view of the NIEHS. The authors declare they have no competing financial interests. Received 4 December 2003 ; accepted 10 January 2005.
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