Natural element as a heavy metal that endangers life. Proven to cause mental retardation, increased infections and cancer rates. Lead blunts the body’s defense mechanisms, the immune system, and collects in blood, bones, and soft tissue. It can cause damage to the brain, as well as the central and peripheral nervous system, and kidneys. People can have lead poisoning symptoms at 0.2 ppm. The medical threshold is 0.4 parts-per-million (ppm) for adults and 0.3 ppm for children. Lead pipes, lead in soil, lead-paint flakes, or motor exhaust with lead compounds as antiknocking or performance enhancing additives in gasoline, can all contribute to water, food, and air contamination.