Selenium, Elemental

CAS RN:7782-49-2

Toxicity Summary

Selenium is an essential trace element and has been shown to be a natural component in the enzyme glutathione peroxidase and other proteins. Most selenium compounds are water-soluble and can efficiently be taken up in the intestine. Soluble as well as non-soluble compounds can be taken up by the lungs. When given in excess, selenium compounds are rapidly distributed to major organs of the body. ... Identified metabolites are trimethylselenide in urine and dimethylselenide in breath. ... in man ... toxic effects have been reported at 1 mg/dl. ... Toxic effects have been seen at blood levels ranging from 0.179 ug/ml-7.5 ug/ml. In most parts of the world normal urine levels do not exceed 0.03 ug/ml. Occupationally exposed workers usually excrete less than 0.1 ug/ml. The LD50 ranges between 1.5 and 6 mg/kg for many selenium compounds and animal species. The CNS seems to be the target organ ... but the liver, heart, and lungs may also be affected. A few cases of selenium poisoning in humans have been described ... either after consumption of selenium or after exposure via inhalation. Gastrointestinal and neurological symptoms predominated. Chronic poisoning due to long term exposure has been reported in livestock and humans from geographical areas where soil contains high levels of selenium. In rodent liver cirrhosis is a common effect while typical effects in domestic animals are: emaciation, deformation of hooves, loss of hair, and joint erosions. In humans consuming 5 mg selenium per day, hair and nail problems are very common. Skin lesions and depigmentation are also common signs of intoxication. In more severe cases neurological and gastrointestinal symptoms predominate. ... Several selenium compounds have been tested for possible carcinogenic potential. Selenium sulfide has been shown to induce liver cancer in two species while no convincing evidence of carcinogenicity has been presented for other selenium compounds. ... Some selenium compounds may induce DNA damage and some previous reports indicate a teratogenic potential ... . Selenium may prevent or alleviate toxic effects of arsenic, cadmium, mercury, platinum, and silver. Conversely, some of these metals protect against selenium toxicity.
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