Studies in Jiangsu Province of China have indicated a reduction in the prevalence of these diseases by taking selenium supplements.
Currently, the largest use of selenium worldwide is in glass manufacturing, followed by uses in chemicals and pigments.
Growth in selenium consumption was historically driven by steady development of new uses, including applications in rubber compounding, steel alloying, and selenium rectifiers.
By 1970, selenium in rectifiers had largely been replaced by silicon, but its use as a photoconductor in plain-paper copiers had become its leading application.
Elemental selenium and most metallic selenides have relatively low toxicities, due to their low bioavailability.
Selenium (chemical symbol Se, atomic number 34) is a chemical element that is classified as a nonmetal.
Selenium deficiency is relatively rare in healthy, well-nourished individuals.
Selenium can combine with metals and oxygen to form selenides (such as sodium selenide, Na2Se), selenates (such as calcium selenate, CaSeO4), and selenites (such as sodium selenite, Na2SeO3).
Selenium also forms hydrogen selenide (H2Se), a colorless, flammable gas that is the most toxic compound of selenium.
Selenium is most commonly produced from selenides that are present in many sulfide ores, particularly those of copper, silver, and lead.
People dependent on food grown from selenium-deficient soil are also at risk.
Selenium deficiency has also been associated with goiter, cretinism, and recurrent miscarriage in humans.
Natural sources of selenium include certain selenium-rich soils, and selenium that has been bioconcentrated by certain toxic plants such as locoweed.
Selenium poisoning of water systems may result from new agricultural runoff through normally dry lands.
Dietary selenium comes from cereals, meat, fish, and eggs.
A list of selenium rich foods can be found at The Office of Dietary Supplements Selenium Fact Sheet.
The selenous acid is finally bubbled with sulfur dioxide to produce red, amorphous selenium.
Liver and Brazil nuts are particularly rich sources of selenium.
Deficiency in selenium can lead to Keshan disease, which is potentially fatal.
The most thermodynamically stable and dense form of selenium is the electrically conductive gray (trigonal) form, composed of long, helical chains of selenium atoms.
Selenium (Greek word ??????, selene, meaning "Moon") was discovered in 1817 by Jцns Jakob Berzelius, who found the element associated with tellurium (named for the Earth).
At present, total global production of selenium continues to increase modestly.
Selenium sulfide is an antifungal agent added to shampoos for the treatment of dandruff.
In 1996, research showed a positive correlation between selenium supplementation and cancer prevention in humans.
When selenium is produced through chemical reactions, it invariably appears as the amorphous, reddish form—an insoluble, brick-red powder.
Anthropogenic sources of selenium include coal burning and the mining and smelting of sulfide ores .
Selenium also exists in three different, deep red, crystalline monoclinic forms, which are composed of eight-membered ring molecules (Se8), similar to many allotropes of sulfur.