Tuesday, May 3, 2011




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] Symptoms from exposure to organic lead, which is probably more toxic than inorganic lead due to its lipid solubility, occur rapidly.[14] Poisoning by organic lead compounds has symptoms predominantly in the central nervous system, such as insomniadeliriumcognitive deficits, tremor, hallucinations, and convulsions.[9]
Symptoms may be different in adults and children; the main symptoms in adults are headache, abdominal painmemory losskidney 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, lethargylearning 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/dLneuropsychiatric effects such as delayed reaction times, irritability, and difficulty concentrating, as well as slowed motor nerve conduction and headache can occur.[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 ofencephalopathy (a condition characterized by brain swelling), such as those that accompany increased pressure within the skulldelirium, 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]