Longitudinal Analysis of Factors Predicting Organophosphate Pesticide Exposure to Children Living in an Agricultural Area at Ages 6, 12, and 24 Months

Abstract

SM3-O-04 Introduction: Farmworker children are vulnerable to higher pesticide exposures because they live and play in nearby agricultural fields, are exposed to pesticide residues on their parents’ work clothes, and may ingest pesticides in the breast milk of a farmworker mother. We investigated pesticide exposures to children living in an agricultural area with intensive pesticide use. Methods: We measured 6 organophosphate (dialkyl phosphate; DAPs) urinary metabolites in samples from children when they were 6 (n = 407), 12 (n = 401), and 24 (n = 383) months old. DAPs were summed to obtain a measure of total exposure to approximately 80% of pesticides applied in the study area. Dimethyl (DMP, DMTP, DMDTP) and diethyl (DEP, DETP, DEDTP) metabolites were also totaled and evaluated individually. We investigated potential exposure risk factors, including age, sex, season, occupation of parents and household members (farmworker/not farmworker), wearing of work clothes into the home, distance of home to the fields, home pesticide use, and diet. Results: Levels increased with age, with total median DAP levels of 37, 54, and 76 nmol/L, respectively (P < 0.01). This increase was driven by the total dimethyl metabolites, which rose from a median of 16 nmol/L to 50 nmol/L between 6 and 24 months. Total diethyl metabolites did not significantly increase over these ages (median, 11–13 nmol/L, respectively). At 6 months of age, summer season, having farmworker household members, the wearing of agricultural work clothes into the home and consumption of canned fruits or vegetables were significantly associated with higher levels of total DAP urinary metabolites (P < 0.05). At 12 months, living less than 200 feet from an agricultural field was significantly associated with higher total DAP levels (P < 0.05). At 24 months, none of the exposure risk factors was statistically associated with total DAP metabolite levels. The findings for total DAP metabolites were driven by the dimethyl metabolites. For diethyls alone, higher levels were associated with canned fruit or vegetable consumption at 6 months and living less than 200 feet from an agricultural field at 12 months. Discussion and Conclusions: Overall, these finding suggest that diet and occupational risk factors are associated with pesticide exposures to very young children. Results for older children were not consistent, potentially due to higher variability in diets, behavior, and locations where children spent time. Findings presented will include the results of multivariate statistical models.