Prenatal exposure to multiple metals and associations with neurodevelopment

Background: Few studies have evaluated the impact of mixed exposures to multiple metals on childhood development. Mixtures may be particularly important at low-level exposures, because at high doses the main effect of a toxic metal may overwhelm any interaction. Aims: We examined additive and multiplicative effects of prenatal mixed metal exposures on early childhood neurodevelopment in a cohort of mother-infant pairs living proximal to an EPA-designated Superfund Site contaminated with metals. Methods: We collected maternal blood samples at delivery and measured arsenic, manganese, and lead concentrations using ICP-MS. We assessed mental (MDI) and motor (PDI) development in 300 children at 12 and/or 24 months of age using Bayley Scales of Infant Development-II. We modeled associations of neurodevelopment with a) metals exposure allowing for interactions between metals, and b) a categorical measure of multiple metal exposure, where an indicator variable was used to represent the number of metals at or abo...