Impact of manganese and metal mixtures in blood, hair, and soil on child adaptive behaviors in Southeast Side Chicago

Background: Manganese (Mn) is essential in growth and development, yet higher levels of Mn are associated with deficits in neurodevelopment. Elevated air Mn was identified near Mn alloy processing facilities in Southeast Side Chicago resulting in community concern about child exposure and health. Methods: Blood, hair, and soil samples were collected and analyzed for multiple metals for children ages 7–17 years and a parent/primary caregiver completed surveys. We used generalized estimating equations to assess associations between metals and the Adaptive Behavior Assessment System 3rd Edition (ABAS-3) scores. Sensitivity analyses were conducted to determine effect modification by child sex on associations between metals and ABAS-3 scores. Bayesian kernel machine regression was used as our principal analytic framework to assess the associations between metal mixtures and adaptive behaviors. Results: The analyses included 108 children. Residential distance from the nearest Mn industrial source was inversely correlated with soil Mn levels and some were above the federal screening level. A significant association was found between soil Mn and lower ABAS-3 score (β: 3.78, 95 % CI: 7.31, −0.25), and between blood Mn and lower scores in females (β: 11.8, 95 % CI: 21.7, −1.87). ABAS-3 scores were negatively associated with the blood metals mixture, primarily driven by Mn. Conclusion: Children in Southeast Side Chicago have elevated levels of soil Mn and soil Mn was associated with poorer ABAS-3 scores. Sex-specific differences were found between metal levels and ABAS-3 scores. After considering multiple metals in mixture, Mn was the primary driver of poorer adaptive behavior.