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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 10 parts per million, ppm, of lead in their blood serum. People who have been exposed to an unusual amount of lead will have lead serum levels higher than 20 ppm - most clinical symptoms of lead poisoning begin at around 100 ppm. The symptoms of lead poisoning include reduced IQ and, in extreme cases, seizure.
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.
Once in the body, lead is biologically inactive – its toxic properties come from lead's ability to mimic other biologically important metals, the most notable of which are iron or zinc. Lead is able to bind to and interact with the same proteins and molecules as iron, but after replacing iron, those molecules function differently and fail to carry out the same reactions.
One measure of lead in the body is the blood lead level (BLL), measured in micrograms of lead per deciliter of blood (micrograms/dL). Nearly everyone has a measurable BLL. The Centers for Disease Control and Prevention (CDC) says that BLLs of 10 micrograms/dL or above are cause for concern. However, even at BLLs below 10 micrograms/dL, lead can impair development.
Most lead poisoning symptoms are thought to occur by interfering with an essential enzymeAn enzyme is a protein, or protein complex, that catalyzes a chemical reaction. Like any catalyst, enzymes work by lowering the activation energy of a reaction, thus allowing the reaction to proceed to its steady state or completion much faster than it ot Delta-aminolevulinic acid dehydratase , or ALAD. ALAD is a zinc binding protein which is important in the biosynthesis of hemeA haem or heme is a metal-containing cofactor that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin''. Although porphyrins do not necessarily contain iron, a substantial fraction of porphyrin-contain, the cofactor found in hemoglobinHaemoglobin ( BE) or hemoglobin ( AE), is the iron-containing oxygen-transport metalloprotein in the red cells of the blood in mammals and other animals. The molecule consists of globin, the apoprotein, and four haem groups, an organic molecule with an ir. Genetic mutations of ALAD cause the disease porphyriaThe porphyrias are inherited or acquired disorders of certain enzymes in the heme biosynthetic pathway (also called porphyrin pathway). They are broadly classified as hepatic porphyrias or erythropoetic porphyrias based on the site of the overproduction a, a disease which was highlighted in the movie The Madness of King GeorgeThe Madness of King George is a 1994 film which tells the story of King George III of Great Britain's deteriorating mental health, and the equally declining relationship between him and his son, the Prince of Wales. It stars Nigel Hawthorne as George III,.