Thorium-228
描述
Thorium is the chemical element of symbol Th and atomic number 90. It is a naturally occurring radioactive metal of the actinide series. In the environment, thorium exists in combination with other minerals, such as silica. Small amounts of thorium are present in all rocks, soil, water, plants, and animals. Twenty-seven radioactive isotopes of thorium, with mass number from 210 to 236, have been characterized. Naturally occurring thorium is composed mainly of one isotope: 232Th. The most abundant and/or stable isotopes are: 232Th (half-life of 14.05 billion years), 230Th (half-life of 75,380 years), 229Th (half-life of 7340 years), and 228Th (half-life of 1.92 years). Thorium is used to make ceramics, gas lantern mantles, and metals used in the aerospace industry and in nuclear reactions. Thorium can also be used as a fuel for generating nuclear energy. Thorium has been linked to increased risk of liver cancer. (L1094, L1838)
类别
"Industrial/Workplace Toxin", "Pollutant", "Airborne Pollutant", "Natural Toxin"
同义词
"228Th", "Thorium 228", "Thorium, isotope of mass 228"
InChI 标识符
InChI=1S/Th/i1-4
键
InChIKey=ZSLUVFAKFWKJRC-AHCXROLUSA-N
化合物类型
Inorganic compounds
大分类
Homogeneous metal compounds
类型
Homogeneous actinide compounds
直接大类
Homogeneous actinide compounds
取代基
"Homogeneous actinide"
地位
Detected and Not Quantified
蜂窝位置
"Cytoplasm", "Extracellular"
暴露途径
Oral (L1838) ; Inhalation (L1838) ; Dermal (L1838)
毒性机制
The ionizing radiation produced by thorium 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)
代谢
Exposure to thorium can occur following inhalation, ingestion, or dermal exposure. Once in the body thorium accumulates mainly in the liver, spleen, lymph nodes, lungs, and bone. Transferrin plays a major role in the transport and cellular uptake of thorium. Thorium may combine with oxygen to form thorotrast (thorium dioxide), a colloid which may affect protein uptake. Thorium and thorotrast are excreted mainly in the faeces. (L1838)
致癌性
1, carcinogenic to humans. (L135)
用途/来源
Thorium can also be used as a fuel for generating nuclear energy. Thorium is used as an alloying element in magnesium, used in aircraft engines, imparting high strength and creep resistance at elevated temperatures. Thorium is also used as an alloying agent in gas tungsten arc welding (GTAW) to increase the melting temperature of tungsten electrodes and improve arc stability. Thorium is used to coat tungsten wire used in electronic equipment, improving the electron emission of heated cathodes. Thorium is used as a fertile material for producing nuclear fuel. Thorium is a very effective radiation shield, although it has not been used for this purpose as much as lead or depleted uranium. Uranium-thorium age dating has been used to date hominid fossils. (L1094)
健康影响
Lungs and other internal organs can be penetrated by the alpha radiation produced by thorium. As a result, exposure to an aerosol of thorium can lead to increased risk of cancers of the lung, pancreas and blood. Exposure to thorium internally leads to increased risk of liver diseases. (L1094)
症状
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)
治疗
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)
维基百科链接
http://en.wikipedia.org/wiki/Thorium-228
创建于
2009-03-06 18:58:06 UTC
更新于
2014-12-24 20:21:08 UTC