Maternal occupational exposure to chemicals and neurocognitive development at 4-5 years of age

Abstract

BACKGROUND AND AIM: Despite evidence that suggests fetal brain development is particularly sensitive to endocrine disrupting chemicals (EDCs), limited data exist regarding childhood neurodevelopment in relation to maternal exposure to EDCs at levels relevant to occupational settings. This study’s objective was to examine the association between maternal occupational EDC exposures and childhood neurocognitive function at 4-5 years of age. METHODS: This analysis included 1,058 mother-child pairs in the {INfancia y Medio Ambiente} (INMA) project (2003-2008). Likelihood of exposure to several EDC groups was estimated using a job-exposure matrix and assigned to each mother based on her self-reported longest held job during her index pregnancy. At her child’s 4-5-year follow-up visit, the McCarthy Scales of Children’s Abilities was administered by a trained psychologist, yielding a general cognitive index and sub-scales of verbal, perceptive-performance and quantitative reasoning. We imputed missing covariate data and analyzed associations separately for each cohort using linear regression, weighting for inverse probability of attrition and adjusting for covariates informed by a directed acyclic graph: maternal age, education, country of birth, parity, gestational weight gain, pre-pregnancy body mass index, smoking and alcohol use during pregnancy, verbal intelligence, child sex and age at assessment, and the psychologist who administered the assessment. Finally, we combined cohort-specific effect estimates using random-effects meta-analysis. RESULTS:We observed an association between maternal occupational exposure to organic solvents and decreased quantitative reasoning scores at age 4-5 (-5.8, 95% confidence interval: -11.0, -0.5). Associations of similar magnitude and direction were observed for the same domain in relation to exposure to alkylphenolic compounds, phthalates and miscellaneous chemicals (i.e., benzophenones, parabens and siloxanes), though these were not statistically significant. CONCLUSIONS:This study found limited evidence for a role of maternal occupational EDC exposures on childhood cognitive function. Further research should consider the combined impact of multiple workplace exposures. KEYWORDS: neurodevelopmental outcomes, chemical exposures, occupational exposures, endocrine disrupting chemicals, solvents, occupational epidemiology