Measurement of children's exposure to pesticides: Analysis of urinary metabolite levels in a probability-based sample

The Minnesota Children's Pesticide Exposure Study is a probability-based sa mple of 102 children 3-13 years old who were monitored for commonly used pe sticides. During the summer of 1997, first-morning-void urine samples (1-3 per child) were obtained for 88% of study children and analyzed for metabol ites of insecticides and herbicides: carbamates and related compounds (1-NA P), atrazine (Ah?), malathion (MDA), and chlorpyrifos and related compounds (TCPy). TCPy was present in 93% of the samples, whereas 1-NAP, MDA, and AM were detected in 45%, 37%, and 2% of samples, respectively. Measured intra child means ranged from 1.4 mug/L for MDA to 9.2 mug/L for TCPy, and there was considerable intrachild variability. For children providing three urine samples, geometric mean TCPy levels were greater than the detection limit in 98% of the samples, and nearly half the children had geometric mean 1-NA P and MDA levels greater than the detection limit. Interchild variability w as significantly greater than intrachild variability for 1-NAP (p = 0.0037) and TCPy (p < 0.0001). The four metabolites measured were not correlated w ithin urine samples, and children's metabolite levels did not vary systemat ically by sex, age, race, household income, or putative household pesticide use. On a log scale, mean TCPy levels were significantly higher in urban t han in nonurban children (7.2 vs. 4.7 mug/L; p = 0.036). Weighted populatio n mean concentrations were 3.9 [standard error (SE) = 0.7; 95% confidence i nterval (CI), 2.5, 5.3] mug/L for 1-NAP, 1.7 (SE = 0.3; 95% CI, 1.1, 2.3) m ug/L for MDA, and 9.6 (SE = 0.9; 95% CI, 7.8, 11) mug/L for TCPy. The weigh ted population results estimate the overall mean and variability of metabol ite levels for more than 84,000 children in the census tracts sampled. Leve ls of 1-NAP were lower than reported adult reference range concentrations, whereas TCPy concentrations were substantially higher. Concentrations of MD A were detected more frequently and found at higher levels in children than in a recent nonprobability-based sample of adults. Overall, Minnesota chil dren's TCPy and MDA levels were higher than in recent population-based stud ies of adults in the United States, but the relative magnitude of intraindi vidual variability was similar for adults and children.