Phthalate Mixtures in Pregnancy and Childhood Behavioral Outcomes

Abstract

TPS 731: Neurological effects in children, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background/Aim: Prenatal exposure to phthalate plasticizers has previously been associated with changes in child behavior, but the typical approach of evaluating each compound independently has led to inconsistent results. Methods: We examined the relationship between a mixture of 11 specific gravity-adjusted urinary phthalate metabolites, averaged across the first and third trimesters of pregnancy, and child behavior at ages 4-6 using the Behavioral Assessment System for Children (BASC) and Social Responsiveness Scale (SRS). Analyses included 499 mother/child pairs (252 girls, 247 boys) participating in The Infant Development and Environment Study, a multi-site pregnancy cohort. We evaluated associations using weighted quantile sum (WQS) regression, which weights individual compound contributions to combined exposure mixture associations, adjusting for demographic and biological covariates. Results: A one quintile increase in the log10-transformed phthalate mixture was significantly associated with 0.7-1.3 point adverse differences in BASC composite externalizing, behavioral symptoms index (BSI), and adaptive skills T scores, as well as SRS total T score. MBP and MIBP accounted for 76% and 74% of the total weighted mixture sum for the externalizing and BSI scores, respectively; MBP and MCPP accounted for 77% for adaptive skills; and the sum of DEHP metabolites (SumDEHP), MCPP, and MBzP accounted for 56% for the total SRS score. Stratifying by sex revealed female-specific adverse associations in externalizing and BSI composite scores highly weighted for MIBP and MBP (88% and 78%, respectively). For adaptive skills, WQS coefficients were similar between sexes, but the most highly weighted phthalates were MBP and MBzP (74%) for females and MCPP and SumDEHP (56%) for males. Conclusions: Our results suggest adverse associations between prenatal phthalate mixtures and childhood behavior with sex-specific impacts, particularly MBP for females and DEHP for males. Further investigation into the potential sex-specific effects of mixtures will improve our understanding of endocrine-disrupting chemical effects on neurobehavioral development.