The presence of lead in water and soil can also be caused by airborne lead particles emitted by automobile exhaust and factory smokestacks. The interior surfaces of about 27 million households in this country are contaminated by lead paint produced before the amount of lead in residential paint was controlled. Children under the age of seven and pregnant women are the most at risk of developing temporary or permanent effects from lead poisoning. An estimated 12 million children under the age of seven live in homes suspected of containing lead-based paint. Though it cannot be destroyed and does not degrade easily, lead does break down into invisible, microscopic particles so light they are easily airborne and dispersed.
Lead poses an immediate health threat when ingested.
Though the body does not need lead, it absorbs it in varying degrees. Once absorbed, it is stored for many years, primarily in the body's tissue. The long-term effect of lead absorption is not yet fully documented, although it is known that cellular damage can result. New studies show that maternal lead levels can damage a child prenatally, lowering birth weight and causing later defects in physical and intellectual development. In middle-aged men, lead poisoning can result in an increased risk of hypertension.