Book excerpt: Neurodevelopmental disorders are generally influenced by genetic as well as intrauterine and extrauterine factors that affect the fetal-maternal environment and/or brain development that continues after birth. Specific genetic polymorphisms may increase susceptibility to environmental factors that alter the trajectory of brain development via diverse molecular mechanisms. In particular, the pre- and post-natal exposure to neurotoxic metals, pesticides, persistent organic pollutants, and other chemicals is increasingly recognized as involved in the pathogenesis of neurodevelopmental disorders, such as autism, deficiency attention/hyperactivity disorders, neurodegenerative disorders such as Parkinson's and Alzheimer's disease, chronic multiple sclerosis, and even fetal and infant death, including SIUDS (Sudden Unexplained Intrauterine Death Syndrome) and SIDS (Sudden Infant Death Syndrome).