Heavy Metal(loid) Body Burden in Environmentally Exposed Children With and Without Internalizing Behavior Problems

The prevalence of internalizing behavior disorders in children is increasing. Reasons for increasing anxiety and depression include several factors with a less studied consideration being the potential neurotoxic effects of environmental exposures. One group at risk for environmental exposures is children living near coal-burning power plants with coal ash storage facilities. Multivariate logistic regression was used to assess the relationship between metal(loid) exposures and internalizing behaviors in children aged 6-14 years. Metal(loid)s in nail samples were determined by Proton-Induced X-ray Emission and internalizing behavior problems were obtained from the parent ratings on the Child Behavior Checklist. Results indicated that concentrations of metal(loid)s in nails differ between children with internalizing behaviors and without internalizing behaviors. Logistic regression models suggested that exposure to zinc and imputed zirconium were associated with internalizing behaviors in children. However, when a sex-metal(loid) interaction term was included, none of the metal(loid)s were associated with internalizing behaviors indicating a role of sex differences in neurotoxicity with zinc and copper showing effects only for males. In all models, greater exposure to traffic was associated with internalizing behaviors. Zinc has previously been shown to increase risk for mental health problems, while zirconium has received less attention. Out findings indicate that environmental exposures of zinc and zirconium deserve further attention in studies of childhood internalizing disorders.