Evaluation of take-home organophosphorus pesticide exposure among agricultural workers and their children

We analyzed organophosphorus pesticide exposure in 218 farm worker households in agricultural communities in Washington State to investigate the take-home pathway of pesticide exposure and to establish baseline exposure levels for a community intervention project. House dust samples (n = 156) were collected from within the homes, and vehicle dust samples (n = 190) were collected from the vehicles used by the farm workers to commute to and from work. Urine samples were obtained from a farm worker (n = 213) and a young child (n = 211) in each household. Dust samples were analyzed for six pesticides, and urine samples were analyzed for five dilkylphosphate (DAP) metabolites. Azinphosmethyl was detected in higher concentrations (p < 0.0001) than the other pesticides: geometric mean concentrations of azinphosmethyl were 0.53 μ/g in house dust and 0.75 μg/g in vehicle dust. Dimethyl DAP metabolite concentrations were higher than diethyl DAP metabolite concentrations in both child and adult urine (p < 0.0001). Geometric mean dimethyl DAP concentrations were 0.13 μmol/L in adult urine and 0.09 μmol/L in child urine. Creatinine-adjusted geometric mean dimethyl DAP concentrations were 0.09 μmol/g in adult urine and 0.14 μmol/g in child urine. Azinphosmethyl concentrations in house dust and vehicle dust from the same household were significantly associated (r²=0.41, p < 0.0001). Dimethyl DAP levels in child and adult urine from the same household were also significantly associated (r² = 0.18, p < 0.0001), and this association remained when the values were creatinine adjusted. The results of this work support the hypothesis that the take-home exposure pathway contributes to residential pesticide contamination in agricultural homes where young children are present.