Using a novel tooth-biomarker method, weekly metal concentrations in deciduous dentine — spanning 19 weeks pre-birth through 43 weeks postnatally — were mapped against adolescent brain activity in a cohort from Mexico City's PROGRESS birth study (ages 8–14). Higher postnatal metal mixture exposure correlated with elevated risk-taking tendency and risk sensitivity, while both prenatal and late-postnatal exposure linked to greater reward sensitivity and reduced angular gyrus activation during risky decisions. Strontium primarily drove risk-related neural changes; magnesium drove reward-related activation shifts in the insula.
This preprint — not yet peer-reviewed — advances environmental neuroscience by moving beyond single-metal analyses toward mixture modeling across precise developmental windows, a methodological leap long needed in the field. The dentine biomarker approach is particularly compelling, offering retrospective temporal resolution unavailable from blood or urine sampling. The angular gyrus finding is notable: this region integrates numerical and contextual reasoning, and its suppression could plausibly impair cost-benefit judgment in adolescence. However, the cohort is specific to an urban Mexican population with distinctive exposure profiles, limiting generalizability. The cross-sectional fMRI assessment cannot confirm causality, and sample size — while adequate for regression — is modest for neuroimaging. Practically, findings reinforce that postnatal metal exposure windows, not just prenatal ones, deserve regulatory and clinical attention. Assessment of this work as confirmatory-plus: it validates mixture-timing concerns while introducing mechanistic neural specificity.