Lead is a very soft, bluish-gray metallic element that has a high density, malleability, some ductility, a high resistance to corrosion, and high electrical conductivity. It occurs naturally in small amounts in the earth's crust, most commonly in compounds with sulfur.
Lead has many uses, including in batteries, ammunition, gasoline and aviation fuel, paints, ceramic products, caulking, solder, pipes, and X-ray shielding. However, there is no known use for lead in the human body. It is a neurotoxin that is easily ingested and accumulates in soft tissues and bones because the body can confuse it with calcium. In the body it can cause a variety of health problems for humans and wildlife, including damaging the nervous system and interfering with the function of enzymes. It is particularly harmful for children and can lead to lower IQs and behavioral problems.
Thus, the use of lead in gasoline, paints, ceramic products, caulking and pipe solder has been greatly reduced in many countries in recent years. This has been a major environmental success. However, much work remains to be done, including removing lead from products in developing countries and from the aviation fuel used by small aircraft and from ammunition.