Prenatal Exposure to Phthalates and Neurodevelopment in the CHAMACOS Cohort

Abstract

Background:

Previous studies suggest that prenatal exposure to phthalates, ubiquitous synthetic chemicals, may adversely affect neurodevelopment. However, data are limited on how phthalates affect cognition, executive function, and behavioral function into adolescence.

Objective:

We aimed to investigate associations of prenatal phthalate exposure with neurodevelopment in childhood and adolescence in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study.

Methods:

We examined associations between maternal urinary phthalate metabolite concentrations measured twice during pregnancy and a range of neurodevelopmental outcomes from ages 7 through 16 y in the CHAMACOS birth cohort ( $n=334$ ). We used age-specific linear regression models and generalized estimating equation models to assess longitudinal effects and examined differences by sex.

Results:

Phthalate metabolites were detected in 88%–100% of samples, depending on the metabolite. Associations of phthalates with neurodevelopmental outcomes were largely null with some noteworthy patterns. Higher prenatal concentrations of metabolites of low-molecular weight phthalates ( $\mathrm{\Sigma }\text{LMW}$ ) were associated with more self-reported hyperactivity [ $\mathrm{\beta }=0.8$ , 95% confidence interval (CI): 0.1, 1.4 per 2-fold increase in $\mathrm{\Sigma }\text{LMW}$ phthalates], attention problems ( $\mathrm{\beta }=1.5$ , 95% CI: 0.7, 2.2), and anxiety ( $\mathrm{\beta }=0.9$ , 95% CI: 0.0, 1.8) at age 16. We observed sex-specific differences for the sums of high-molecular-weight and di(2-ethylhexyl) metabolites and cognitive outcomes (e.g., $\mathrm{\beta }$ for Full-Scale IQ for $\text{boys}=-1.9$ , 95% CI: $-4.1$ , 0.3 and $-1.7$ , 95% CI: $-3.8$ , 0.3, respectively; $\mathrm{\beta }$ for $\text{girls}=1.8$ , 95% CI: 0.1, 3.4 and 1.6, 95% CI: 0.0, 3.2, respectively; $p\text{-int}=0.01$ for both).

Conclusion:

We found predominantly null associations of prenatal phthalates with neurodevelopment in CHAMACOS, and weak associations of $\mathrm{\Sigma }\text{LMW}$ phthalates with internalizing and externalizing behaviors in adolescence. No previous studies have examined associations of prenatal phthalate exposure with neurodevelopment into adolescence, an important time for manifestations of effects. https://doi.org/10.1289/EHP5165