Review of residue-based selenium toxicity thresholds for freshwater fish.

A variety of guidelines have been proposed in recent years for linking selenium concentrations in the whole body of fish or in diet with adverse effects in fish. Diverging viewpoints seem to be forming separating groups supporting either the low-selenium guidelines proposed by the government and academic researchers or the high-selenium guidelines proposed by other researchers. Recently, an article was published that reviewed selected studies and recommended guidelines for selenium concentrations in the whole body of fish and in diet that were higher than those proposed by other researchers (approximately 4 microg/g in whole body and 3-4 microg/g in diet). That article also recommended separating guidelines for coldwater fish (6 microg/g in whole body and 11 microg/g in diet) and warmwater fish (9 microg/g in whole body and 10 microg/g in diet). The approaches, information, and guidelines presented in the article are reviewed and problems in their interpretation and conclusions are discussed. The majority of the selenium literature supports a whole-body threshold of 4 microg/g in fish and 3 microg/g in diet.