Overview. While fetal exposure to toxic elements has been associated with metabolic disease, and some of these associations are sex-specific, it is unclear if these associations are causal. The overall goal of MET-DETOX is to provide causal evidence as to whether fetal exposure to toxic ele- ments predisposes to type 2 diabetes (T2D) and components of the metabolic syndrome. This will be achieved by identifying maternal and fetal genetic and gene x environmental determinants of toxic elements in fetal cord blood and using this information to undertake Mendelian randomization (MR) studies. Since levels of environmental toxicants are modifiable, understanding their etiologic role could support key public health interventions to decrease the burden of metabolic disease in Canada.