Definition
An element with the atomic symbol Se, atomic number 34, and atomic weight 78.96. It is an essential micronutrient for mammals and other animals but is toxic in large amounts. Selenium protects intracellular structures against oxidative damage. It is an essential component of GLUTATHIONE PEROXIDASE. Essential dietary component Although it is toxic in large doses, selenium is an essential micronutrient for animals.
Description
Selenium is a nonmetal element with the atomic number 34 and the chemical symbol Se. Isolated selenium occurs in several different forms, the most stable of which is a dense purplish-gray semiconductor form. Selenium rarely occurs in its elemental state in nature and is usually found in sulfide ores such as pyrite, partially replacing the sulfur in the ore matrix. It may also be found in silver, copper, lead, and nickel minerals. Selenium is mainly used in the electronics industry, in glassmaking, and in chemicals and pigments. Though selenium salts are toxic in large amounts, trace amounts of the element are necessary for cellular function in most animals, forming the active center of the enzymes glutathione peroxidase, thioredoxin reductase, and three known deiodinase enzymes. (L620)
Top Gene Interactions
Related Pathways
Selenium Health Effects
- Analgesic
- Anorexic
- Anti acne
- Anti angiogenic
- Anti arthritic
- Anti asthmatic
- Anti atherosclerotic
- Anti cataract
- Anti cirrhotic
- Anti climacteric
- Anti coronary
- Anti depressant
- Antidote
- Anti fibrotic
- Anti gout
- Anti HIV
- Anti keshan
- Anti leukemic
- Anti leukotriene
- Anti maculitic
- Anti melanomic
- Anti menopausal
- Anti metastatic
- Anti myalgic
- Anti NF-kappa-B
- Anti osteoarthritic
- Antioxidant
- Anti Parkinsonian
- Anti proliferant
- Anti radicular
- Anti rheumatic
- Anti syndrome-X
- Antitumor
- Anti ulcerogenic
- Anxiolytic
- Activator-protein-1 inhibitor
- Cancer preventive
- Cardioprotective
- Depressant
- Fungicide
- Immunomodulator
- Immunostimulant
- NF-kappa-B inhibitor
- Ornithine-decarboxylase inhibitor
- Pesticide
- Protein kinase C inhibitor
- Polyamine synthesis inhibitor
- Prostaglandin sparer
- VEGF inhibitor
- Anti aggregant
- Anti dandruff
- Apoptotic
General Information
- Metabolism:
Selenium may be absorbed through inhalation and ingestion, while some selenium compounds may also be absorbed dermally. Once in the body, selenium is distributed mainly to the liver and kidney. Selenium is an essential micronutrient and is a component of glutathione peroxidase, iodothyronine 5'-deiodinases, and thioredoxin reductase. Organic selenium is first metabolized into inorganic selenium. Inorganic selenium is reduced stepwise to the intermediate hydrogen selenide, which is either incorporated into selenoproteins after being transformed to selenophosphate and selenocysteinyl tRNA or excreted into the urine after being transformed into methylated metabolites of selenide. Elemental selenium is also methylated before excretion. Selenium is primarily eliminated in the urine and feces, but certain selenium compounds may also be exhaled. (L619)
- Uses/Sources:
Most processed selenium is used in the electronics industry, but it is also used as a nutritional supplement, in the glass industry, in the preparation of pharmaceuticals, as a nutritional feed additive for poultry and livestock, in pesticide formulations, in rubber production, as an ingredient in antidandruff shampoos, and as a constituent of fungicides. It may also be found in pigments in plastics, paints, enamels, inks, and rubber. (L619)
- Health Effects: Chronic oral exposure to high concentrations of selenium compounds can produce a disease called selenosis. The major signs of selenosis are hair loss, nail brittleness, and neurological abnormalities (such as numbness and other odd sensations in the extremities). Animal studies have shown that selenium may also affect sperm production and the female reproductive cycle. (L619)
- Symptoms:
Short-term oral exposure to high concentrations of selenium may cause nausea, vomiting, and diarrhea. Brief exposures to high levels of elemental selenium or selenium dioxide in air can result in respiratory tract irritation, bronchitis, difficulty breathing, and stomach pains. Longer-term exposure to either of these air-borne forms can cause respiratory irritation, bronchial spasms, and coughing. (L619)
- Route of Exposure:
Oral(L619) ; inhalation (L619) ; dermal (L619).
Toxicity
- Carcinogenicity: 3, not classifiable as to its carcinogenicity to humans. (L135)
- Toxicity: LD50: 6700 mg/kg (Oral, Rat) (T14)
- Minimum Risk Level: Chronic Oral: 0.005 mg/kg/day (L134)