Many of the most toxic materials on Earth--from arsenic to plutonium--occur naturally, but manufacturers have also used them in products such as paints, plumbing, pesticides, nuclear fuel, and weaponry. Without careful management, toxins can leach into groundwater or pollute our environment. Exposure to toxins leads to various cancers, impairment of the immune and reproductive systems, as well as cognitive problems. What can be done? Solutions include a wide range of infrastructure approaches, such as better water filtration, governmental and manufacturing regulations, outright bans on certain chemicals, careful monitoring, and the use of alternative fuels. Learn more about key contaminants and their impact on health, as well as solutions on a global and individual level.