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.