Levels of the heavy metals cadmium, lead, and arsenic and the essential mineral manganese, measured in maternal blood during pregnancy, were associated with increased risk of ADHD and/or autism in the child. This was reported in a new study from the Norwegian Institute of Public Health. This research does not show that metals and minerals are a direct cause of ADHD or autism because observed associations may have other explanations; however, the findings show the importance of more knowledge about how environmental contaminants may impact fetal development.