Prenatal exposure to toxicants and child language development in the Norwegian Mother, Father and Child Cohort Study (MoBa)

Abstract

BACKGROUND AND AIM: Prenatal toxicant exposures have been associated with increased risk of language difficulties in children. Much of this work has yet to explore which toxicant among correlated exposures might be most influential; therefore, we examined the effect of prenatal exposure to phthalates, organophosphate esters (OPEs), and organophosphorous pesticides (OPPs) on children’s language development from toddlerhood to the preschool period. METHODS: The study included 1022 pregnant women that were selected from the MoBa cohort run by the Norwegian Institute of Public Health. Prenatal concentrations of toxicant metabolites (6 phthalates, 4 OPEs, and 6 dialkylphosphate pesticides) were measured in maternal urine collected at 17 weeks gestation. Children’s language was assessed with parent report on the Ages and Stages Questionnaire at 18 months, and teacher report on the Child Development Inventory at preschool age. We used structural equation models to account for multiple exposures on each developmental outcome separately and also ran multigroup analyses to examine potential child sex differences. RESULTS:Prenatal low molecular weight phthalates were associated with better language development at 18 months (β=.08, 95% CI: 0.01, 0.14); however, they were associated with more adverse language development in the preschool period (β=-.11, 95% CI: -0.22, 0.00). OPPs were associated with worse language development at 18 months (β=-.09, 95% CI: -0.16, -0.02), and a slight negative association in preschool (β=-.10, 95% CI: -0.21, 0.01). High molecular weight phthalates and organophosphate esters were not associated with language development at either age, nor were there differences by child sex for any toxicant. Follow-up analyses will consider developmental trajectories. CONCLUSIONS:In models accounting for mixed exposures, we found that prenatal toxicants were associated with language development in a potentially age-dependent manner, but that did not vary by child sex. Differences in associations by child age may reflect patterns of brain development in early life. KEYWORDS: pesticides, phthalates, neurodevelopmental outcomes, mixtures analysis