Lead is a toxic metal which has no known function in the human body; indeed, all recorded effects of lead on living organisms are detrimental. We know that lead bioaccumulates and that it persists in living organisms. In its pure form, is not changed by exposure to sunlight, air or water.
In addition to posing a threat to human health, acute lead toxicity can produce detrimental effects on eco-systems. These effects include low growth rates in plants; developmental, reproductive and nervous system problems in mammals, birds, and fish; and, in severe cases, death. Lead is highly toxic to aquatic life, particularly in soft water. Since lead bioaccumulates in the tissues of living organisms, it can result in secondary toxicity in animals and humans at the top levels of the food chain.
Physical characteristics of lead: Lead is a bluish-gray metal found in small amounts in the earth's crust. It occurs naturally and is typically present as lead oxide, lead salts and organic salts. It is also highly dense, malleable, resistant to corrosion, and has a low melting point -- characteristics which account for its continued use in a variety of manufacturing processes. (Lead is heavily used in battery production, as well as in the manufacturing of ammunition, solder and pipes, pigments, cable coverings, bearings, caulking, roofing, X-ray shields, and in some ceramics and crystal production. Leaded gasoline, leaded paints and cottage industries such as battery production, smelting and recycling are important contributors to a wide-spread lead exposure problem, especially in economically developing nations).