Lead-210
描述
Lead is a heavy metal and stable element with the symbol Pb and the atomic number 82, existing in metallic, organic, and inorganic forms. It is mainly found in nature as the mineral galena (PbS), cerussite (PbCO3) or anglesite (PbSO4), usually in ore with zinc, silver, or copper. Lead is highly malleable and corrosion-resistant, with its use being traced back to ancient times. Inicidences of lead poisoning have also been documented in the ancient Greek, Roman, and Chinese societies. Lead-210 is a radioactive isotope of lead. (L21)
类别
"Industrial/Workplace Toxin", "Pollutant", "Airborne Pollutant", "Natural Toxin"
同义词
"(210)Pb", "210Pb", "Lead 210", "Lead, isotope of mass 210"
InChI 标识符
InChI=1S/Pb/i1+3
键
InChIKey=WABPQHHGFIMREM-AKLPVKDBSA-N
地位
Detected and Not Quantified
蜂窝位置
"Cytoplasm", "Extracellular"
外貌
Bluish-white metallic solid, turns grey when exposed to air.
暴露途径
Oral (L136) ; inhalation (L136) ; dermal (L136)
毒性机制
Lead mimics other biologically important metals, such as zinc, calcium, and iron, competing as cofactors for many of their respective enzymatic reactions. For example, lead has been shown to competitively inhibit calcium's binding of calmodulin, interferring with neurotransmitter release. It exhibits similar competitive inhibition at the NMDA receptor and protein kinase C, which impairs brain microvascular formation and function, as well as alters the blood-brain barrier. Lead also affects the nervous system by impairing regulation of dopamine synthesis and blocking evoked release of acetylcholine. However, it's main mechanism of action occurs by inhibiting delta-aminolevulinic acid dehydratase, an enzyme vital in the biosynthesis of heme, which is a necesssary cofactor of hemoglobin. The ionizing radiation produced by lead-210 causes cellular damage that includes DNA breakage, accurate or inaccurate repair, apoptosis, gene mutations, chromosomal change, and genetic instability. This leads to loss of normal cell and tissue homeostasis, and development of malignancy. Ionizing radiation that does not directly damage DNA can produce reactive oxygen intermediates that directly affect the stability of p53, an important enzyme in cell-cycle regulation, and produce oxidative damage to individual bases in DNA and point mutations by mispairing during DNA replication. (L1837, T4, A20, A22, L136)
代谢
Lead is absorbed following inhalation, oral, and dermal exposure. It is then distributed mainly to the bones and red blood cells. In the blood lead may be found bound to serum albumin or the metal-binding protein metallothionein. Organic lead is metabolized by cytochrome P-450 enzymes, whereas inorganic lead forms complexes with delta-aminolevulinic acid dehydratase. Lead is excreted mainly in the urine and faeces. (L136)
致癌性
Internalized radionuclides that emit β particles are carcinogenic to humans (Group 1) (L2150). Lead-210 primarily undergoes beta decay.
用途/来源
Lead is used extensively in building construction and can also be found in batteries, ammunition, non-Western cosmetics, solder, and pipes. Old paints and ceramic products may also contain lead, though recent legislation has banned its use. (L136)
最低风险等级
Chronic Inhalation: 0.05 mg/m3 (L134)
健康影响
Lead is a neurotoxin and has been known to cause brain damage and reduced cognitive capacity, especially in children. Lead exposure can result in nephropathy, as well as blood disorders such as high blood pressure and anemia. Lead also exhibits reproductive toxicity and can results in miscarriages and reduced sperm production. As lead-210 is radioactive, it can cause cancer. (L21)
症状
Symptoms of chronic lead poisoning include reduced cognitive abilities, nausea, abdominal pain, irritability, insomnia, metal taste in the mouth, excess lethargy or hyperactivity, chest pain, headache and, in extreme cases, seizures, coma, and death. There are also associated gastrointestinal problems, such as constipation, diarrhea, vomiting, poor appetite, weight loss, which are common in acute poisoning. Exposure to high doses of ionizing radiation results in acute radiation syndrome, which can cause skin burns, hair loss, nausea, vomiting, dizziness, disorientation, low blood pressure, headache, fatigue, weakness, fever, birth defects, illness, infection, and death. (L1837, L1852, A2, L21)
治疗
Lead poisoning is usually treated with chelation therapy using DMSA, EDTA, or dimercaprol. Treatment reversing the effects of irradiation is currently not possible. Anaesthetics and antiemetics are administered to counter the symptoms of exposure, as well as antibiotics for countering secondary infections due to the resulting immune system deficiency. (L1852, L21)
创建于
2009-03-06 18:58:07 UTC
更新于
2014-12-24 20:21:09 UTC