Selenium and its compounds

Selenium exists in various chemical forms (speciation) and oxidation states that can affect its occurrence, properties, use and toxicity. Human exposures occur in the workplace, and via food and drinking water, through dermal, inhalation or ingestion routes involving organic or inorganic forms. Ingestion of the organic form from food, including dietary supplements, is the main source of exposure for the general population. Evaluation of exposure and health effects of selenium has to consider both essentiality and toxicity. The occupational and environmental limits and reference values that are established are associated with the specific route of exposure and the chemical form, where data exist, as shown below (CDC 1996, 2010; ICPS 2001).