Selenium exists in four natural oxidation states (+6, +4, 0, and –2) and is found in several compounds capable of causing human poisoning, yet it is an essential trace element in the human diet. Table II–59 describes physical properties and toxic air concentrations or doses of common selenium compounds. Fatal acute selenium poisoning occurs most commonly from ingestion of selenious acid in gun bluing (coating) solutions. Other acute poisonings occur through the use of (often improperly formulated) dietary supplements as well as via exposure to industrial compounds. Illness caused by chronic exposure to selenium is uncommon but is seen in regions with high selenium content in food. Industries using selenium compounds include ceramics, electronics, glass, rubber, and metallurgy. Selenium dioxide is the most commonly used compound industrially. Selenium is produced largely as a by-product of copper refining.
TABLE II–59.SELENIUM COMPOUNDS ||Download (.pdf) TABLE II–59. SELENIUM COMPOUNDS
|Compound (Synonyms) ||Physical Properties ||Toxic Dose or Air Concentrationa |
CASRN 7782-49-2 (Se)
|Amorphous or crystalline, red to gray solid ||PEL 0.2 mg/m3; idLH 1 mg/m3 |
CASRN 7783-07-5 (H2Se)
|Odiferous colorless gas ||PEL 0.05 ppm; idLH 1 ppm |
CASRN 1313-85-5 (Na2Se)
|Red to white powder ||PEL 0.2 mg/m3 (as Se) |
CASRN 7783-00-8 (H2SeO3)
|White powder encountered as 2% solution in gun bluing ||Ingestion of as little as 15 mL of a 2% solution was reportedly fatal in a child. |
|White powder ||Mean lethal dose of selenite salts in dogs was 4 mg/kg. Human ingestion of 1–5 mg/kg caused moderate toxicity. |
CASRN 7446-08-4 (O2Se)
|White crystal or powder ||PEL 0.2 mg/m3 (as Se) |
|White crystals ||PEL 0.2 mg/m3 (as Se) |
CASRN 7783-08-6 (H2SeO4)
|White solid ||PEL 0.2 mg/m3 (as Se) |
CASRN 7783-79-1 (F6Se)
|Colorless gas ||PEL 0.05 ppm; idLH 2 ppm |
Precise cellular toxopathology is poorly understood. Animal studies implicate mechanisms involving the formation of superoxide and hydroxyl anions as well as hydrogen peroxide. Mechanistic knowledge makes no contribution to treatment currently. A garlic breath odor observed in various selenium poisonings is due to in vivo creation of dimethyl selenium.
Acute overdose. Rapidly fatal overdoses have occurred from ingestion of gun bluing solutions containing 2–9% selenious acid and 2–4% copper. Ingestion of 15 mL of gun bluing solution containing 4% selenious acid was fatal. The oral mean ...