Concentrations of selective metabolites of organophosphorus pesticides in the United States population

We report population-based concentrations (stratified by age, sex, and composite race/ethnicity variables) of selective metabolites of chlorpyrifos (3,5,6-trichloro-2-pyridinol; TCPY), chlorpyrifos methyl (TCPY), malathion (malathion dicarboxylic acid; MDA), diazinon (2-isopropyl-4-methyl-6-hydroxypyrimidine; IMPY), methyl parathion (para-nitrophenol; PNP), and parathion (PNP). We measured the concentrations of TCPY, MDA, IMPY, and PNP in 1997 urine samples from participants, aged 6-59 years, of the National Health and Nutrition Examination Survey, 1999-2000. We detected TCPY in more than 96% of the samples tested. Other organophosphorus pesticide metabolites were detected less frequently: MDA, 52%; IMPY, 29%; and PNP, 22%. The geometric means for TCPY were 1.77 μg/L and 1.58 μg/g creatinine. The 95th percentiles for TCPY were 9.9 μg/L and 8.42 μg/g creatinine. The 95th percentiles for MDA were 1.6 μg/L and 1.8 μg/g creatinine. The 95th percentiles for IMPY and PNP were 3.7 μg/L (3.4 μg/g creatinine) and 5.0 μg/L (4.2 μg/g creatinine), respectively. Multivariate analyses showed that children aged 6-11 years had significantly higher concentrations of TCPY than adults and adolescents. Similarly, adolescents had significantly higher TCPY concentrations than adults. Although the concentrations between sexes and among composite racial/ethnic groups varied, no significant differences were observed.