Background: Children are especially vulnerable to pesticide exposure and can suffer lasting health effects. Because children of farmworkers are exposed to a variety of pesticides throughout development, it is important to explore temporal patterns of coexposures. Objectives: The objectives of this study were to characterize the pesticide co-exposures, determine how they change over time, and assess differences between farmworker and nonfarmworker households. Methods: Dust collected from 40 farmworker and 35 nonfarmworker households in the Yakima Valley of the State of Washington in 2005 and then again in 2011 was analyzed for 99 pesticides. Eighty-seven pesticides representing over 28 classes were detected. Pesticides were grouped into classes using U.S. EPA pesticide chemical classifications, and trends in concentrations were analyzed at the class level. Results: Levels of organophosphates, pyridazinones, and phenols significantly decreased between 2005 and 2011 in both farmworker and nonfarmworker households. Levels of anilides, 2,6-dinitroanilines, chlorophenols, triclosan, and guanidines significantly increased in both farmworker and nonfarmworker households in 2011 vs. 2005. Among farmworkers alone, there were significantly lower levels of N -methyl carbamates and neonicotinoids in 2011. Conclusions: We observed significant reductions in the concentrations of many pesticides over time in both farmworker and nonfarmworker households. Although nonfarmworker households generally had lower concentrations of pesticides, it is important to note that in comparison with NHANES participants, nonfarmworkers and their families still had significantly higher concentrations of urinary pesticide metabolites. This finding highlights the importance of detailed longitudinal exposure monitoring to capture changes in agricultural and residential pesticide use over time. This foundation provides an avenue to track longitudinal pesticide exposures in an intervention or regulatory context. https://doi.org/10.1289/EHP3644

The exposome provides a conceptual model for identifying and characterizing lifetime environmental exposures and resultant health effects. In this study, we applied key exposome concepts to look specifically at the neurodevelopmental pesticide exposome, which focuses on exposures to pesticides that have the potential to cause an adverse neurodevelopmental impact. Using household dust samples from a children’s agricultural cohort located in the Yakima Valley of Washington state, we identified 87 individual pesticides using liquid chromatography-tandem mass spectrometry. A total of 47 of these have evidence of neurotoxicity included in the Environmental Protection Agency (EPA) (re)registration materials. We used a mixed effects model to model trends in pesticide exposure. Over the two study years (2005 and 2011), we demonstrate a significant decrease in the neurodevelopmental pesticide exposome across the cohort, but particularly among farmworker households. Additional analysis with a non-parametric binomial analysis that weighted the levels of potentially neurotoxic pesticides detected in household dust by their reference doses revealed that the decrease in potentially neurotoxic pesticides was largely a result of decreases in some of the most potent neurotoxicants. Overall, this study provides evidence that the neurodevelopmental pesticide exposome framework is a useful tool in assessing the effectiveness of specific interventions in reducing exposure as well as setting priorities for future targeted actions.

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