See also occupational disease.
Many of the traditional sources of lead in the United States have been minimized by a variety of federal laws, enacted from 1978 on, banning lead paint and glazes and leaded gasolines, and prohibiting the use of lead pipes in construction and the use of lead solder in food and soda cans. Workplace exposure has been regulated by laws requiring the use of respirators, dust suppressors, and proper ventilation, and lead waste disposal guidelines have been developed. Continuing sources of environmental lead include water that has passed through old lead pipes, paint in older buildings, lead improperly disposed of in public landfills, and industrial sources such as mining, smelting, and recycling processes necessary to produce lead for batteries and other products.
Young children are usually exposed by ingesting paint chips containing lead. This source is most prevalent in poor areas where old, peeling lead-containing paint and plaster in rundown housing is common. Inadequately nourished or emotionally deprived children who resort to chewing inedible things (a condition known as pica) are most susceptible.
Acute lead poisoning can result in abdominal discomfort, nervous system damage, and encephalitis. Chronic exposure is characterized by a blue line on the gums and can lead to damage to the brain, kidneys, nervous system, and red blood cells. Even low levels can contribute to hypertension in older people or to "silent lead poisoning" in exposed children, which affects the developing brain and leads to visual-motor problems and lowered intelligence. Lower doses may be treated by altering the diet to counteract lead's effects and and cleaning the person's environment to reduce intake. Higher doses are treated with chelating agents, drugs that remove lead from the body. Symptoms recur upon subsequent exposure.
Poisoning by accumulation of lead in the body. Large doses cause gastroenteritis in adults and brain disorders in children. Anemia, constipation and abdominal spasm, confusion, a progressive paralysis, and sometimes brain cancer result from chronic exposure. Children are particularly susceptible to nerve and brain damage; sensitive tests show that even low levels of lead can harm children and are linked to behavioral problems. Sources in the home include lead-based paint, lead drinking-water pipes, and lead-glazed tableware. Babies, who put things in their mouths, are at highest risk. Working where lead is used and exposure to some insecticides are other risk factors. The U.S. phaseout of lead in gasoline was completed in 1996; similar bans are being implemented worldwide. Treatment involves giving antidotes that bind (see chelate) the lead in the tissues.
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