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Մասնակից:Aelita sar/Ավազարկղ

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The amount of lead in the blood and tissues, as well as the time course of exposure, determine toxicity.[1] 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.[2] 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). Urine lead levels may be used as well, though less commonly. In cases of chronic exposure lead often sequesters in the highest concentrations first in the bones, then in the kidneys. If a provider is performing a provocative excretion test, or "chelation challenge", a measurement obtained from urine rather than blood is likely to provide a more accurate representation of total lead burden to a skilled interpreter.[3]

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.[4][5] Authorities such as the American Academy of Pediatrics define lead poisoning as blood lead levels higher than 10 μg/dL.[6]

Lead forms a variety of compounds and exists in the environment in various forms.[7] Features of poisoning differ depending on whether the agent is an organic compound (one that contains carbon), or an inorganic one.[8] 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.[8] Organic lead compounds, which cross the skin and respiratory tract easily, affect the central nervous system predominantly.[8]

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Symptoms of lead poisoning.

Lead poisoning can cause a variety of symptoms and signs which vary depending on the individual and the duration of lead exposure.[9][10] Symptoms are nonspecific and may be subtle, and someone with elevated lead levels may have no symptoms.[11] 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.[12] Symptoms from exposure to organic lead, which is probably more toxic than inorganic lead due to its lipid solubility, occur rapidly.[13] Poisoning by organic lead compounds has symptoms predominantly in the central nervous system, such as insomnia, delirium, cognitive deficits, tremor, hallucinations, and convulsions.[8]

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.[14]

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.[15] Other early signs in adults include malaise, fatigue, decreased libido, and problems with sleep.[9] An unusual taste in the mouth and personality changes are also early signs.[16]

In adults, symptoms can occur at levels above 40 μg/dL, but are more likely to occur only above 50–60 μg/dL.[9] Symptoms begin to appear in children generally at around 60 μg/dL.[17] However, the lead levels at which symptoms appear vary widely depending on unknown characteristics of each individual.[18] 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 conduction and headache can occur.[19] Anemia may appear at blood lead levels higher than 50 μg/dL.[15] In adults, abdominal colic, involving paroxysms of pain, may appear at blood lead levels greater than 80 μg/dL.[10] 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.[20] In children, signs of encephalopathy such as bizarre behavior, discoordination, and apathy occur at lead levels exceeding 70 μg/dL.[20] For both adults and children, it is rare to be asymptomatic if blood lead levels exceed 100 μg/dL.[10]

  1. ↑ Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Pearson03» անվանումով ref-երը տեքստ չեն պարունակում:
  2. ↑ Trevor, Katzung, Masters (2007) p. 479
  3. ↑ Lowry, Jennifer A. (2010) ORAL CHELATION THERAPY FOR PATIENTS WITH LEAD POISONING Արխիվացված 2016-01-26 Wayback Machine. WHO
  4. ↑ Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Rossi09» անվանումով ref-երը տեքստ չեն պարունակում:
  5. ↑ Barbosa Jr, F; Tanus-Santos, JE; Gerlach, RF; Parsons, PJ (2005). «A Critical Review of Biomarkers Used for Monitoring Human Exposure to Lead: Advantages, Limitations, and Future Needs». Environmental Health Perspectives. 113 (12): 1669–74. doi:10.1289/ehp.7917. PMC 1314903. PMID 16330345.
  6. ↑ Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Ragan09-JAAPA» անվանումով ref-երը տեքստ չեն պարունակում:
  7. ↑ Grant (2009) p. 761
  8. ↑ 8,0 8,1 8,2 8,3 Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Katzung07-948» անվանումով ref-երը տեքստ չեն պարունակում:
  9. ↑ 9,0 9,1 9,2 Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Karri08» անվանումով ref-երը տեքստ չեն պարունակում:
  10. ↑ 10,0 10,1 10,2 Kosnett (2005) p. 825
  11. ↑ Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Mycyk05-463» անվանումով ref-երը տեքստ չեն պարունակում:
  12. ↑ Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Dart041426» անվանումով ref-երը տեքստ չեն պարունակում:
  13. ↑ Timbrell, J.A., ed. (2008). «Biochemical mechanisms of toxicity: Specific examples». Principles of Biochemical Toxicology (4th ed.). Informa Health Care. ISBN 978-0-8493-7302-2.
  14. ↑ Pearce, JM (2007). «Burton's line in lead poisoning». European Neurology. 57 (2): 118–9. doi:10.1159/000098100. PMID 17179719.
  15. ↑ 15,0 15,1 Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Merrill07» անվանումով ref-երը տեքստ չեն պարունակում:
  16. ↑ Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Patrick06» անվանումով ref-երը տեքստ չեն պարունակում:
  17. ↑ Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Need2004» անվանումով ref-երը տեքստ չեն պարունակում:
  18. ↑ Քաղվածելու սխալ՝ Սխալ <ref> պիտակ՝ «Bellinger04-Pedi» անվանումով ref-երը տեքստ չեն պարունակում:
  19. ↑ Kosnett (2006) p.240
  20. ↑ 20,0 20,1 Henretig (2006) p. 1314
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