Prenatal and Childhood Exposure to Organophosphate Pesticides and Behavior Problems in Adolescents and Young Adults in the CHAMACOS Study

Background: We previously reported associations of prenatal exposure to organophosphate (OP) pesticides with poorer neurodevelopment in early childhood and at school age, including poorer cognitive function and more behavioral problems, in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), a birth cohort study in an agriculture community.

Objective: We investigated the extent to which early-life exposure to OP pesticides is associated with behavioral problems, including mental health, in youth during adolescence and early adulthood.

Methods: We measured urinary dialkylphosphates (DAPs), nonspecific OP metabolites, in urine samples collected from mothers twice during pregnancy (13 and 26 wk) and at five different times in their children (ages 6 months to 5 y). We assessed maternal report and youth report of externalizing and internalizing behavior problems using the Behavior Assessment System for Children, 2nd edition (BASC-2), when the youth were ages 14, 16, and 18 y. Because there was evidence of nonlinearity, we estimated associations across quartiles of DAPs and modeled repeated outcome measures using generalized estimating equations.

Results: There were 335 youths with prenatal maternal DAP measures and 14-. 16-, or 18-y BASC-2 scores. Prenatal maternal DAP concentrations (specific gravity-adjusted median, $Q1-Q3=159.4$, $78.7-350.4\text{nmol}/L$) were associated with higher T-scores (more behavior problems) from maternal report, including more hyperactivity [fourth vs. first quartile of exposure $\beta =2.32$; 95% confidence interval (CI): 0.18, 4.45], aggression ($\beta =1.90$; 95% CI: 0.15, 3.66), attention problems ($\beta =2.78$; 95% CI: 0.26, 5.30), and depression ($\beta =2.66$; 95% CI: 0.08, 5.24). Associations with youth report of externalizing problems were null, and associations with depression were suggestive (fourth vs. first quartile of exposure $\beta =2.15$; 95% CI: $-0.36$, 4.67). Childhood DAP metabolites were not associated with behavioral problems.

Discussion: We found associations of prenatal, but not childhood, urinary DAP concentrations with adolescent/young adult externalizing and internalizing behavior problems. These findings are consistent with prior associations we have reported with neurodevelopmental outcomes measured earlier in childhood in CHAMACOS participants and suggests that prenatal exposure to OP pesticides may have lasting effects on the behavioral health of youth as they mature into adulthood, including their mental health. https://doi.org/10.1289/EHP11380.