Exposure to neurotoxic metals early in life can disrupt brain development and increase risk of later mental health problems, but vulnerable periods and underlying mechanisms remain unclear. We examined how early life exposures to mixtures of metals affect children’s brain and behavior using naturally shed “baby” teeth as a biomarker of direct exposure. We studied 489 children aged 8 to 14 years and reconstructed weekly concentrations of nine metals from 20 weeks before birth to 40 weeks after bi