Children’s everyday chemical contaminant exposure: Associations with demographic disparities and the developing basal ganglia

Abstract

Children are regularly exposed to chemical contaminants that rodent research suggests may influence brain development. However, relatively little is known about how these contaminants impact the developing human brain. This dissertation examined whether the mixture of everyday chemical contaminants to which children are exposed is associated with the developing basal ganglia—a brain region that may be particularly susceptible to harm from contaminant exposure. Analyses further assessed for demographic disparities in contaminant exposures to clarify how potential developmental risks are distributed across the population. Stability in exposures over time was also explored. Sixty-two children (M= 7.00 years, 53.23% female, 66.13% White) provided data on their brain structure via structural neuroimaging and wore a silicone wristband—a newly validated exposure assessment tool—to track their chemical contaminant exposure over a seven day period. In over 75% of wristbands, 48 chemicals were detected, including plasticizers, flame retardants, organophosphate esters, pesticides, combustion by-products, and even one banned legacy contaminant. Notable demographic disparities in exposure were present, such that Non-White and lower-income children were more exposed to several contaminants. While chemical contaminant mixture exposure was not associated with overall basal ganglia volume, two organophosphate esters (2IPPDPP and 4IPPDPP) commonly used as flame retardants and plasticizers were both associated with a larger globus pallidus, a basal ganglia sub-region. Finally, exposure to roughly half of the frequently detected chemicals was stable over time in a small sub-sample (N= 12). Results indicate to which contaminants children are regularly exposed, highlight demographic disparities in exposure, and suggest possible risks to brain development that require replication in larger, more diverse samples.