Prenatal environmental exposures and child neurodevelopment in Project Viva
Harris, Maria Hemphill
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Background: The prenatal period is a critical window for neurodevelopment and is particularly sensitive to toxicant exposure. Traffic-related air pollution and per- and polyfluoroalkyl substances (PFASs) are two classes of potential developmental toxicants to which pregnant women are ubiquitously exposed. Objectives: In a cohort of children, characterize in utero exposure to traffic-related air pollution and PFASs and examine the effects of these exposures on childhood assessments of neurodevelopment. Methods: Analyses were conducted in Project Viva, a longitudinal Boston-area birth cohort enrolled during 1999‒2002. In mid-childhood (at age 6‒10), children completed assessments of cognitive function and mothers and classroom teachers assessed executive function and behavior problems in children using validated questionnaires. Estimates of traffic-related pollutant exposures, residential proximity to major roadways, and near-residence traffic density were generated for periods in pregnancy and childhood. Stored maternal plasma from pregnancy was analyzed for concentrations of four common PFASs: perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA). We modeled associations of exposures with neurodevelopmental assessment scores, adjusted for potential confounders. Results: Living within 50 meters of a major roadway at birth predicted lower non-verbal intelligence, verbal intelligence, and visual motor abilities in mid-childhood. Children with higher black carbon exposure during childhood had greater teacher-assessed problems with behavior regulation, but prenatal traffic exposures were not associated with greater problems. Children with higher prenatal exposure to PFOA scored lower on assessments of verbal IQ and visual motor abilities, but children with the highest levels of PFOS and PFNA exposure appeared to have better scores on some cognitive assessments (verbal IQ, non-verbal IQ and design memory for PFOS and verbal IQ, design memory and picture memory for PFNA). Conclusions: The influence of exposure to traffic-related pollution and PFASs on neurodevelopment varied across pollutants, exposure windows, and neurobehavioral domains. Results suggested that residential proximity to major roadways during gestation adversely affected cognitive development. Prenatal exposure to traffic-related pollution did not predict greater neurobehavioral problems, but childhood exposure appeared to influence behavioral regulation. Observed associations of prenatal PFAS exposure with childhood cognition differed across studied compounds and cognitive assessments, suggesting both deleterious and protective effects.