Selenium (C.A.S. 7782-49-2) is a naturally occurring element widely but unevenly distributed in the earth's crust and commonly found in sedimentary rock formations. It is also manufactured for industrial uses. Humans are exposed to selenium daily in their food, particularly in grains, cereals, meat, seafood and drinking water.

Industry uses selenium as a black, gray or red odorless solid to manufacture "electric eyes," photographic exposure meters, rectifiers for home entertainment equipment, xerography, red or black glass, anti-dandruff shampoos, and pigments in plastics, paints, enamels, inks and rubber. It is also used in veterinary medicine and as a fungicide and insecticide.

In some regions of the U.S., soils contain high levels of selenium and selenium compounds, which accumulate in plants and can be toxic to grazing livestock. In fresh water containing elevated levels of selenium, such as in the highly publicized Kesterson Reservoir in California, fish may contain extremely high levels of selenium. The Kesterson Reservoir receives selenium-laden water runoff fromnearby agricultural areas.

Identification:

• Chemical Name: Selenium Powder
• Regulatory Name: Selenium
• Formula: Se
• CAS: 7782-49-2
• STCC: 4925219
• UN Number: 2658

Health effects:

Selenium and its compounds, particularly selenium dioxide and hydrogen selenide, can cause eye irritation. Inhalation of selenium dust, a concentrated mist of selenium, selenium dioxide or hydrogen selenide, can irritate the nose, throat and bronchial tubes and cause headaches, dizziness and malaise. Exposure to high concentrations of selenium dioxide can cause bronchial spasms, symptoms of asphyxiation and bronchitis.

Ingestion of high doses of selenium compounds can cause pulmonary edema and lung lesions. Acute oral doses of selenium compounds can cause aches and pains, irritability, chills and tremors. Both acute inhalation of and acute oral exposure to selenium compounds cause respiratory distress.

Repeated exposure to selenium can cause metallic taste, a garlic odor to the breath, fatigue, irritability, depression and pallor. Repeated exposure to selenium compounds in food can cause dental cavities and loss of nails and hair. Repeated higher exposures to selenium also may cause liver damage. Inhalation of selenium, selenium dioxide and hydrogen selenide can cause indigestion and nausea.

Most studies have not found a link between selenium and cancer; there are no studies available about the reproductive effects of selenium. It is not known if selenium causes lung damage.

In industrial uses, electronics and photography account for 46% of selenium use; glass industry, 27%; pigments, 14%; miscellaneous, 13%.

Exposure Values:

• IDLH: 1 mg/m3 (as Se)(NIOSH, 1997)
• TLV TWA: 0.2 mg/m3 (NIOSH 1997)
• NIOSH REL: TWA 0.2 mg/m3
• OSHA PEL: TWA 0.2 mg/m3

Regulation:

Permissible exposure limits of selenium are regulated by OSHA; the FDA regulates permissible levels of selenium in bottled water. Several EPA offices regulate selenium: the Office of Drinking Water; the Office of Water Regulations and Standards, under the National Pollutant Discharge Elimination System; the Office of Emergency and Remedial Response; the Office of Solid Waste; and the Office of Toxic Substances, as a pollutant under the Emergency Planning and Community Right to Know Act.

Under Section 313 of the Emergency Planning and Community Right to Know Act of 1986, releases of more than one pound of selenium into the air, water, and land must be reported annually and entered into the Toxic Release Inventory (TRI).

National Overview of 1998 Toxics Release Inventory

See EPA's Toxic Release Inventory.

Return to Index