Periconceptional and prenatal exposure to metal mixtures in relation to behavioral development at three years of age in the New Hampshire Birth Cohort Study

Abstract

PDS 73: Neurological effects, Johan Friso Foyer, Floor 1, August 26, 2019, 10:30 AM - 12:00 PM Background: Behavioral effects of early life exposure to several neurotoxic metals are incompletely understood. Methods: We investigated periconceptional and prenatal exposure to metals, metalloids, and other trace elements in relation to child behavior in the New Hampshire Birth Cohort Study, an ongoing prospective rural birth cohort study enrolling pregnant women with private wells for household water. Toxic (Pb, Hg, As) and essential (Mn, Zn, Se) trace elements were measured in maternal toenails at approximately 24-28 weeks gestation and 6 weeks postpartum and in placenta. Parents completed the Behavior Assessment System for Children, 2nd ed. (BASC-2) and the Social Responsiveness Scale, 2nd ed. (SRS-2) to assess neurobehavioral development at three years. In preliminary analyses, we used Bayesian Kernel Machine Regression (BKMR) to investigate associations between the BASC-2 Behavioral Symptoms Index (BSI; median: 280) and SRS-2 Total Score (median: 23) with ln-transformed trace elements concentrations adjusting for potential confounders (SRS-2: n=487; BASC-2: n=417). Higher scores on these assessments indicate more maladaptive behaviors. Results: The trace elements were detected with high frequency (% detect: median = 0.95; range = 0.66-1.00). Using BKMR with hierarchical variable selection, maternal gestational toenail concentrations (Posterior Inclusion Probability (PIP): 56%) were more strongly associated with SRS-2 Total Scores than placental (PIP: 42%) or maternal postpartum toenail (PIP: 29%) concentrations. Mn (PIP: 65%) was the most strongly associated trace element measured during pregnancy, and the inverse relation with Total Scores appeared linear. Generalized Linear Models also identified an inverse association between ln-transformed maternal gestational toenail Mn and Total Scores (β: -1.71; 95% CI: -2.99,-0.43). Further, ln-transformed maternal gestational Mn concentrations were inversely related to BSI scores, albeit imprecisely (β: -2.83; 95% CI: -6.51, 0.85). Conclusions: Our preliminary results suggest a potential protective role of periconceptional Mn exposures against adverse early childhood behavior, including abnormal social and communicative behavioral skills.