Correspondence: preformed biomarkers in produce inflate human organophosphate exposure assessments.

Produce Inflate Human Organophosphate Exposure Assessments We read the recent report by Curl et al. (2003) concerning organophosphate (OP) pesticide exposures with considerable interest. It seems to have escaped their notice that OP pesticides yield the same dialkylphosphate (DAP) products in urine whether they are human metabolites or formed in treated fruits and vegetables and consumed in the diet. Because the same metabolites arise from foods, the conclusions of Curl et al. regarding eating conventional and organic diets are not justified. Curl et al. (2003) measured urine levels of DAPs of children 2–5 years of age and claimed different exposures based on whether the children consumed organic or conventional diets. Parents kept a food diary during the 2 days before the day of urine sampling. Eighteen of the children ate nearly all organic produce and juice; 21 others consumed conventional produce and juice. Not surprisingly, the children that consumed the conventional diets had more nontoxic DAPs in their urine than did those on an organic diet. The most prominent DAP metabolites were dimethylthiophosphate (DMTP) and diethylthiophosphate (DETP). The median total dimethyl metabolite concentration was about six times higher for children with conventional diets than for children with organic diets. The investigators erred by attributing the urinary DAPs to ingested OP pesticides in foods. Additionally, Curl et al. (2003) transformed the dimethyl metabolites to low, benign levels of oxydemeton-methyl (2.2 μg/kg/day), azinphosmethyl (2.8 μg/kg/day), phosmet (2.8 μg/kg/day), and malathion (2.3 μg/kg/day). Curl et al. (2003) concluded,