Lead poisoning
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fr:Saturnisme Lead poisoning is a condition, also known as plumbism or painter's colic, caused by increased levels of blood serum lead levels. The average person has less than 10 micrograms per deciliter, or 100 parts per billion, ppb, of lead in their blood serum. People who have been exposed to an unusual amount of lead will have lead serum levels higher than 200 ppb—most clinical symptoms of lead poisoning begin at around 100 ppb. The symptoms of lead poisoning include reduced IQ, rashes, irritability, insomnia, excess lethargy or hyperactivity, poor appetite, headache and, in extreme cases, seizure and coma.
Outside of occupational hazards, the majority of lead poisoning occurs in children under age twelve. The main sources of poisoning are ingestion of lead contaminated soil (this is less of a problem in countries that no longer have leaded gasoline) and lead based paints. This is particularly a problem in older houses where the sweet-tasting lead paint is likely to chip. In most states, landlords and those selling such houses are required to inform the potential residents of the danger. A direct link between early lead exposure and extreme learning disability has been confirmed by multiple researchers and child advocacy groups.
Lead has no known biological role in the body. The toxicity comes from its ability to mimic other biologically important metals, the most notable of which are calcium, iron and zinc. Lead is able to bind to and interact with the same proteins and molecules as these metals, but after displacement, those molecules function differently and fail to carry out the same reactions, such as in producing enzymes necessary for certain biological process.
One measure of lead in the body is the blood lead level (BLL), measured in micrograms of lead per deciliter of blood (μg/dL). Nearly everyone has a measurable BLL. The Centers for Disease Control and Prevention (CDC) states that a BLL of 10 μg/dL or above is a cause for concern. However, lead can impair development even at BLLs below 10 μg/dL.
Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme Delta-aminolevulinic acid dehydratase, or ALAD. ALAD is a zinc-binding protein which is important in the biosynthesis of heme, the cofactor found in hemoglobin. Genetic mutations of ALAD cause the disease porphyria, a disease which was highlighted in the movie The Madness of King George.
Famous cases of lead poisoning
- The Devon colic was caused by the presence of lead in cider in 18th century Devon
See also
External link
- Helping Parents Prevent Lead Poisoning (http://www.ericdigests.org/2003-2/lead.html)