Lead is a naturally occurring bluish-gray metal found in small amounts in the earth's crust. It has no characteristic taste or smell. Metallic lead does not dissolve in water and does not burn. Lead can combine with other chemicals to form what are usually known as lead salts. Some natural and manufactured substances contain lead, but do not look like lead in its metallic form.
Lead has many different uses, the most popular being in the production of some types of batteries. It is also used in the production of ammunition, electronics, military equipment, roofing products, medical equipment, metal products (such as sheet lead, solder, some brass and bronze products, and pipes), ceramic glazes, caulking, and paint. Organic lead compounds were once used as gasoline additives to increase the octane rating. As a result of legislative action, the use of lead has been dramatically reduced in many of its former applications.
"Primary" sources of industry lead are mined ores, and "secondary" sources are typically recycled scrap metal and batteries. Human activities such as the combustion of fossil fuels, including gasoline before 1978, and manufacturing processes continue to spread lead compounds to all parts of the environment. As a result, almost all plants and animals have some fraction of lead in them.
Health effects. Inhalation and water consumption are the main routes of entry to the body for lead and lead compounds. However, lead may also enter the body through ingestion of paint chips or soil, and through inadvertent ingestion after touching an object covered with lead dust and touching one's mouth. According to the Centers for Disease Control, there is no known threshold of ...