Many of the most toxic materials on Earth-from arsenic to plutonium-occur naturally, but manufacturers have also used them in common products, such as paints, plumbing, pesticides, nuclear fuel, and weaponry. Without careful management, toxins can leach into groundwater and pollute our environment. Exposure to toxic elements leads to various cancers, impairment of the immune and reproductive systems, as well as cognitive problems. What can be done? Learn more about the chemistry of key contaminants, their history, impact on health, spills and other disasters, as well as solutions on a global and individual level.