Selenium

IARC Cancer Review: Group 3 IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 7 ,1987,p. 56.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) . Selenium and its compounds are on the Community Right-To-Know List. Reported in EPA TSCA Inventory.

Poison by inhalation and intravenous routes. Questionable carcinogen with experimental tumorigenic and teratogenic data. Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath and sweat, gastrointestinal disturbances, and dermatitis. Liver damage in experimental animals. Chronic ingestion of 5 mg of selenium per day resulted in 49% morbidity in 5 Chinese villages. The main symptoms were brittle hair with intact follicles, new hair with no pigment, brittle nails with spots and streaks, skin lesions, peripheral anesthesia, acroparesthesia, pain, and hyperreflexia. Similar effects have been seen in populations with selenium blood levels of 800 µg/L. In cattle, “alkali disease” is associated with consumption of grain or plants containing 5–25 mg/kg of selenium. The symptoms are lack of vitality, loss of appetite, emaciation, deformation and shedding of hoofs, loss of hair, and erosion of joints. Consumption of plants grown in seleniferous areas can cause effects in humans and animals. Selenosis in humans has occurred from ingestion of 3.2 mg selenium per day. Selenium is an essential trace element for many species. Reacts to form explosive products with metal amides. Can react violently with barium carbide, bromine pentafluoride, calcium carbide, chlorates, chlorine trifluoride, chromic oxide (CrO₃), fluorine, lithium carbide, lithium silicon (Li₆Si₂), metals, nickel, nitric acid, sodium, nitrogen trichloride, oxygen, potassium, potassium bromate, rubidium carbide, zinc, silver bromate, strontium carbide, thorium carbide, uranium. When heated to decomposition it emits toxic fumes of Se. See also SELENIUM COMPOUNDS.
Hazard Codes: T
Risk Statements: 36/38-53-33-23/25 
R23/25:Toxic by inhalation and if swallowed. 
R33:Danger of cumulative effects. 
R36/38:Irritating to eyes and skin. 
R53:May cause long-term adverse effects in the aquatic environment.
Safety Statements: 26-61-45-28-20/21 
S20:When using, do not eat or drink. 
S21:When using do not smoke. 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S28:After contact with skin, wash immediately with plenty of soap-suds. 
S45:In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) 
S61:Avoid release to the environment. Refer to special instructions / safety data sheets. 

OSHA PEL: TWA 0.2 mg(Se)/m³
ACGIH TLV: TWA 0.2 mg(Se)/m³
DFG MAK: 0.1 mg(Se)/m³
DOT Classification:  6.1; Label: KEEP AWAY FROM FOOD

For occupational chemical analysis use OSHA: #ID-125G or NIOSH: Elements (ICP), 7300.

The Selenium , with the cas number 7782-49-2, a chemical element with the atomic number 34, and, also exists in many non-conductive forms: a black glass-like allotrope, as well as several red crystalline forms built of eight-membered ring molecules. It is found in economic quantities in sulfide ores and occurs in several different forms, the most stable of which is a dense purplish-gray semi-metal form that is structurally a trigonal polymer chain. Its natural sources include certain selenium-rich soils, and selenium that has been bioconcentrated by certain plants. Native selenium is a rare mineral, which does not usually form good crystals, but when it does they are steep rhombohedrons or tiny acicular (hair-like) crystals. Selenium has five naturally occurring isotopes are stable: 74Se, 76Se, 77Se, 78Se, and 80Se. It is toxic in large doses, but Selenium is an essential micronutrient for animals. Dietary selenium comes from nuts, cereals, meat, fish, and eggs.

It belongs to the following product categories:(1)Inorganics; (2)Pure ElementsChemical Synthesis; (3)SeleniumMetal and Ceramic Science; (4)Catalysis and Inorganic Chemistry; (5)Electronic Chemicals; (6)Micro/Nanoelectronics; (7)Metal and Ceramic Science; (8)Metals; (9)Selenium and so on. It seems to be dark grey to dark red powder or crystals. It is quite stable but combustible, incompatible with strong acids, strong oxidizing agents and most common metals.

Uses of Selenium: Although it is toxic in large doses, selenium is an essential micronutrient for animals. Besides, Selenium also plays a role in the functioning of the thyroid gland and in every cell that utilizes thyroid hormone, by participating as a cofactor for the three known thyroid hormone deiodinases, which activate and then deactivate various thyroid hormones and their metabolites. One study, which was known as the NPC, was conducted to test the effect of selenium supplementation on the recurrence of skin cancers on selenium-deficient men. And, several studies have suggested a possible link between cancer and selenium deficiency. Also, some research has indicated a geographical link between regions of selenium-deficient soils and peak incidences of HIV/AIDS infection. It has been showed that selenium intake is positively correlated with the risk of developing type 2 diabetes.

When you are using this chemical, please be cautious about it as the following: It is quite irritating to eyes and skin. In addition, it is toxic by inhalation and if swallowed and bring danger of cumulative effects. When using, do not eat or drink or smoke. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. After contact with skin, wash immediately with plenty of soap-suds. Most important of all, it may cause long-term adverse effects in the aquatic environment. Hence, you would better avoid release to the environment refering to special instructions / safety data sheets.

You can still convert the following datas into molecular structure :
(1).SMILES: [Se-2]
(2).InChI:InChI=1/Se/q-2

Toxic information of Selenium can be showed as follows: