Essential trace element
Deficiency found to be the cause of Keshan disease and Kashin-beck disease
Recommended daily dose is 5 μg/d
Gun bluing solution
Dietary supplement
Antidandruff shampoo
Glass decolorizer and manufacturing
Insecticide
Vulcanization of rubber
Used in copper refineries
Cofactor in glutathione peroxidase
Varied GI absorption
Minimal dermal absorption
Bioavailability (Lowest - Highest)
Elemental<unk> 
Inorganic selenite and selenate salt
Selenious acid
Limited data on toxicokinetics as it varies amongst compounds
Elemental<unk> 
Inorganic selenite and selenate salt
Selenious acid
Selenium toxicity
Aluminum toxicity
Mercury toxicity
Antimony toxicity
Copper toxicity
Arsenic toxicity
Gold toxicity
Barium toxicity