The purpose of this chapter is to briefly describe some of the organizations that have established regulatory limits for metals. These include nongovernmental organizations such as the American Conference of Governmental Industrial Hygienists, American Industrial Hygiene Association, International Agency for the Research on Cancer, United Nations Environmental Program, and government organizations including the Department of Transportation, Environment Canada, National Institute for Occupational Safety and Health, National Toxicology Program, Organization for Economic Co-operation and Development, Occupational Safety and Health Administration, and the US Environmental Protection Agency.