Lead poisoning
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| Lead poisoning | |
|---|---|
| Classification and external resources | |
 An X ray demonstrating the characteristic finding of lead poisoning, dense metaphyseal lines. | |
| ICD-10 | T56.0 |
| ICD-9 | 984.9 |
| DiseasesDB | 7307 |
| MedlinePlus | 002473 |
| eMedicine | article/815399 |
| MeSH | D007855 |
Lead poisoning (also known as plumbism, colica Pictonum, saturnism, Devon colic, or painter's colic) is a medical condition caused by increased levels of the heavy metal lead in the body. Lead interferes with a variety of body processes and is toxic to many organs and tissues including the heart, bones, intestines, kidneys, and reproductive and nervous systems. It interferes with the development of the nervous system and is therefore particularly toxic to children, causing potentially permanent learning and behavior disorders. Symptoms include abdominal pain, headache, anemia, irritability, and in severe cases seizures, coma, and death.
Routes of exposure to lead include contaminated air, water, soil, food, and consumer products. Occupational exposure is a common cause of lead poisoning in adults. One of the largest threats to children is lead paint that exists in many homes, especially older ones; thus children in older housing with chipping paint are at greater risk. Prevention of lead exposure can range from individual efforts (e.g. removing lead-containing items such as piping or blinds from the home) to nationwide policies (e.g. laws that ban lead in products or reduce allowable levels in water or soil).
Elevated lead in the body can be detected by the presence of changes in blood cells visible with a microscope and dense lines in the bones of children seen on X-ray. However, the main tool for diagnosis is measurement of the blood lead level; different treatments are used depending on this level. The major treatments are removal of the source of lead and chelation therapy (administration of agents that bind lead so it can be excreted).
Humans have been mining and using this heavy metal for thousands of years, poisoning themselves in the process. Although lead poisoning is one of the oldest known work and environmental hazards, the modern understanding of the small amount of lead necessary to cause harm did not come about until the latter half of the 20th century. No safe threshold for lead exposure has been discovered—that is, there is no known amount of lead that is too small to cause the body harm.
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[edit] Classification
Classically, "lead poisoning" or "lead intoxication" has been defined as exposure to high levels of lead typically associated with severe health effects.[1] Poisoning is a pattern of symptoms that occur with toxic effects from mid to high levels of exposure; toxicity is a wider spectrum of effects, including subclinical ones (those that do not cause symptoms).[2] However, professionals often use "lead poisoning" and "lead toxicity" interchangeably, and official sources do not always restrict the use of "lead poisoning" to refer only to symptomatic effects of lead.[2]
The amount of lead in the blood and tissues, as well as the time course of exposure, determine toxicity.[3][4] Diagnosis and treatment of lead exposure are based on blood lead level (the amount of lead in the blood), measured in micrograms of lead per deciliter of blood (μg/dL). The US Centers for Disease Control and Prevention and the World Health Organization state that a blood lead level of 10 μg/dL or above is a cause for concern; however, lead may impair development and have harmful health effects even at lower levels, and there is no known safe exposure level.[5][6] Authorities such as the American Academy of Pediatrics define lead poisoning as blood lead levels higher than 10 μg/dL.[7] Lead poisoning may be acute (from intense exposure of short duration) or chronic (from repeat low-level exposure over a prolonged period), but the latter is much more common.
Lead forms a variety of compounds and exists in the environment in various forms.[8] Features of poisoning differ depending on whether the agent is an organic compound (one that contains carbon), or an inorganic[9] Organic lead poisoning is now very rare, because countries across the world have phased out the use of organic lead compounds as gasoline additives, but such compounds are still used in industrial settings.[9]central nervous system[9] one. Organic lead compounds, which cross the skin and respiratory tract easily, affect the predominantly.
[edit] Signs and symptoms
Lead poisoning can cause a variety of symptoms and signs which vary depending on the individual and the duration of lead exposure.[10][11] Symptoms are nonspecific and may be subtle, and someone with elevated lead levels may have no symptoms.[12] Symptoms usually develop over weeks to months as lead builds up in the body during a chronic exposure, but acute symptoms from brief, intense exposures also occur.[13][14] Poisoning by organic lead compounds has symptoms predominantly in the central nervous system, such as insomnia, delirium, cognitive deficits, tremor, hallucinations, and convulsions.[9] Symptoms from exposure to organic lead, which is probably more toxic than inorganic lead due to its lipid solubility, occur rapidly.
Symptoms may be different in adults and children; the main symptoms in adults are headache, abdominal pain, memory loss, kidney failure, male reproductive problems, and weakness, pain, or tingling in the extremities.[15] The classic signs and symptoms in children are loss of appetite, abdominal pain, vomiting, weight loss, constipation, anemia, kidney failure, irritability, lethargy, learning disabilities, and behavior problems.[15] Children may also experience hearing loss, delayed growth, drowsiness, clumsiness, or loss of new abilities, especially speech skills.[12] Symptoms may appear in children at lower blood lead levels than in adults.[16]
Early symptoms of lead poisoning in adults are commonly nonspecific and include depression, loss of appetite, intermittent abdominal pain, nausea, diarrhea, constipation, and muscle pain.[17] Other early signs in adults include malaise, fatigue, decreased libido, and problems with sleep.[10] An unusual taste in the mouth and personality changes are also early signs.[18] In adults, symptoms can occur at levels above 40 μg/dL, but are more likely to occur only above 50–60 μg/dL.[10] Symptoms begin to appear in children generally at around 60 μg/dL.[19] However, the lead levels at which symptoms appear vary widely depending on unknown characteristics of each individual.[20] At blood lead levels between 25 and 60 μg/dL, neuropsychiatric effects such as delayed reaction times, irritability, and difficulty concentrating, as well as slowed motor nerve[21] Anemia may appear at blood lead levels higher than 50 μg/dL.[17] In adults, Abdominal colic, involving paroxysms of pain, may appear at blood lead levels greater than 80 μg/dL.[11] Signs that occur in adults at blood lead levels exceeding 100 μg/dL include wrist drop and foot drop, and signs of encephalopathy (a condition characterized by brain swelling), such as those that accompany increased pressure within the skull, delirium, coma, seizures, and headache.[22] In children, signs of encephalopathy such as bizarre behavior, discoordination, and apathy occur at lead levels exceeding 70 μg/dL.[22] For both adults and children, it is rare to be asymptomatic if blood lead levels exceed 100 μg/dL.[11] conduction and headache can occur.
[edit] Acute poisoning
In acute poisoning, typical neurological signs are pain, muscle weakness, paraesthesia, and, rarely, symptoms associated with encephalitis.[15] Abdominal pain, nausea, vomiting, diarrhea, and constipation are other acute symptoms.[23] Lead's effects on the mouth include astringency and a metallic taste.[23] Gastrointestinalconstipation, diarrhea, poor appetite, or weight loss, are common in acute poisoning. Absorption of large amounts of lead over a short time can cause shock (insufficient fluid in the circulatory system) due to loss of water from the gastrointestinal tract.[23] Hemolysis (the rupture of red blood cells) due to acute poisoning can cause anemia and hemoglobin in the urine.[23] Damage to kidneys can cause changes in urination such as decreased urine output.[23] People who survive acute poisoning often go on to display symptoms of chronic poisoning.[23] problems, such as
[edit] Chronic poisoning
Chronic poisoning usually presents with symptoms affecting multiple systems,[9] but is associated with three main types of symptoms: gastrointestinal, neuromuscular, and neurological.[15] Central nervous system and neuromuscular symptoms usually result from intense exposure, while gastrointestinal symptoms usually result from exposure over longer periods.[23] Signs of chronic exposure include loss of short-term memory or concentration, depression, nausea, abdominal pain, loss of coordination, and numbness and tingling in the extremities.[18] Fatigue, problems with sleep, headaches, stupor, slurred speech, and anemia are also found in chronic lead poisoning.[15] A "lead hue" of the skin with pallor is another feature.[24] A blue line along the gum, with bluish black edging to the teeth is another indication of chronic lead poisoning.[25] Children with chronic poisoning may refuse to play or may have hyperkinetic or aggressive behavior disorders.[15]
[edit] Exposure routes
Lead is a common environmental pollutant.[7] Causes of environmental contamination include industrial use of lead, such as is found in plants that process lead-acid batteries or produce lead wire or pipes, and metal recycling and foundries.[26] Children living near facilities that process lead, such as smelters, have been found to have unusually high blood lead levels.[27] In August 2009, parents rioted in China after lead poisoning was found in nearly 2000 children living near zinc and manganese smelters.[28] Lead exposure can occur from contact with lead in air, household dust, soil, water, and commercial products.[5]
