Prenatal exposure to polybrominated diphenyl ethers (PBDEs) and cognitive ability in early childhood

Abstract

Background: Prenatal exposure to polybrominated diphenyl ethers (PBDEs) has been associated with adverse neurodevelopmental outcomes in children, but evidence remains mixed regarding sex differences in this association.

Objective: To examine the prospective association between prenatal PBDE exposure and cognitive ability in young children, as well as potential sex differences.

Methods: The study was conducted in a multi-site Canadian pregnancy cohort recruited in 2008-11. PBDEs were measured in maternal plasma samples collected early in pregnancy. Cognitive ability was assessed using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) in children at age 3 years (mean = 3.4). Multiple linear regression was used to analyze the association between maternal PBDE plasma concentrations (lipid-standardized and log10-transformed) and Verbal, Performance, and Full Scale IQ scores on the whole sample and stratified by sex, adjusting for confounders.

Results: The sample was composed of 592 children (291 boys and 301 girls). A tenfold increase in maternal blood PBDE concentration (sum of BDE-47, -99, -100, and -153) was associated with lower Full Scale scores in boys (-3.4 points; 95% CI: -7.0, 0.1), after adjusting for confounders. BDE-47 was the congener with the highest concentrations in maternal blood and a tenfold increase in exposure was associated with significantly lower Full Scale IQ scores in boys (-4.4 points; 95% CI: -7.9, -0.9), after adjusting for confounders. Verbal and Performance IQ scores were similarly associated with PBDE exposure. Maternal blood PBDE concentrations were not associated with IQ scores in girls.

Conclusions: Prenatal exposure to background levels of PBDEs, especially BDE-47, was associated with lower IQ scores in boys, but not in girls. Our results support that exposure to PBDEs during early development may be sex-dependent and detrimental to a child's neurodevelopmental trajectory.

Keywords: Cognitive ability; Neurodevelopment; Polybrominated diphenyl ethers; Pregnancy cohort.