Mercury See Also: Chemical Elements Also called quickSilver, Metalallic Element, known to the ancient Chinese, Hindus, and Egyptians. Silver-white and mirrorlike, it is the only common metal existing as a liquid (see States Of Matter) at ordinary Temperatures. Mercury is used in Barometers, thermometers, electric Switches, mercury-vapor lamps, and certain Battery(s); a mercury alloy, called an amalgam, is employed in dentistry. Mercury Compounds have been used as insecticides, in rat poisons, and as disinfectants. Not easily discharged from the body, the metal is a cumulative poison; its ingestion in more than trace amounts in contaminated food or its absorption by the skin or mucous membranes results in mercury poisoning, which can cause skin disorders, hemorrhage, liver and kidney damage, and gastrointestinal disturbances. Workers in many industries have been affected, and mercury pollution of rivers, lakes, and oceans, usually through the discharge of industrial wastes, has become a serious environmental problem. Most mercury pesticides have been withdrawn from the U.S. market, and in 1972 more than 90 nations approved an international ban on the dumping of mercury in the ocean, where the metal has tended to work its way into the food cycle of aquatic life and to reach dangerous levels in certain food fish.