Lead is a bluish-gray metal, with no characteristic smell or taste, found in small amounts in the earth’s crust. Lead can be used for commercial purposes in its pure metal form or mixed with other metals in an alloy form. It can also be used as a chemical compound, most commonly a form of lead oxide. Until 1991 chemicals containing lead such as tetraethyl lead and tetramethyl lead were used as additives in gasoline. These were banned as a result of the Clean Air Act because of their toxicity. There are 129 lead compounds listed in the National Library of Medicine’s Hazardous Substances Data Bank. Lead is hazardous in all its forms.