Prenatal individual and mixed exposure to metals and trace elements and preschoolers' internalizing and externalizing...

Studies have focused on the effects of toxic metals and trace elements on child behavioral problems. Findings are inconsistent, and the effects of mixtures of elements remain unclear.

We measured manganese (Mn), cadmium (Cd), thallium (Tl), molybdenum (Mo), and selenium (Se) concentrations in the first, second, and third trimesters and cord blood among 2514 mother-child dyads from the Ma'anshan Birth Cohort. To assess children's behavioral development, we used the Child Behavior Checklist for Ages 1.5-5. Generalized linear models, Bayesian kernel machine regression, and Quantile g-computation were applied to analyze individual and mixed associations between metals and trace elements and preschoolers' internalizing and externalizing symptoms.

Maternal serum Cd, Tl, and Mo concentrations in the second trimester were positively associated with internalizing symptoms scores, externalizing symptoms scores and total problems scores (P < 0.05). Se was negatively associated with internalizing symptoms scores, externalizing symptoms scores and total problems scores (β_{internalizing} = -6.91, 95%CI: -11.95, -1.87; β_{externalizing} = -7.23, 95 %CI: -11.25, -3.21; β_total = -8.00, 95 %CI: -12.12, -3.89). The association between Cd and internalizing and externalizing was more pronounced in boys. Exposure to metal mixtures in cord blood was negatively associated with total problems scores.

Prenatal exposure to Cd, Tl, and Mo was associated with an increased risk of behavioral problems in children, with the associations exhibiting sex differences. Conversely, Se may confer a protective effect against childhood behavioral problems. Further studies are warranted to support the findings and explore the mechanism of sex -specific disparity.