↑ MMA (i.e. As) ↑ risk (i.e., IRRs; incidence ratio risk) of iInternalizing Problems (6.9%), Externalizing Problems (7.3%) and Total Behavior Problems (5.9%)↑ Pb ↑ risk of Internalizing Problems (5.7%), Externalizing Problems (6.9%) and Total Behavior Problems (4.6%)In boys, ↑ Pb, ↑ Internalizing Problems , ↑ Externalizing Problems and ↑ Total Behaviour Problems (IRRs increase 7.3%, 9.6% and 5.1%, respectively)Associations between Pb and MMA and Total Behaviour Problems was modified by BDMF rs110301014 genotype. This evidence concerns the gene MTAP and Atypical behavior.