The CAST report followed the proposed reversion to old selenium-use standards by the government, which was a response to concerns about selenium toxicity to wildlife that had occurred at the Kesterson Reservoir in California and some other localities. The scientists found no evidence that supplemental selenium use for farm animals and poultry, including feedlot concentrations, was involved in any environmental problems.
Selenium is an essential nutrient, the report says.
It has been used in supplemental feeding, injections, and other means for 20 years in the United States and some other countries. The level of permitted usage has been increased several times for producers of animals and poultry over the years because experience showed this was necessary for good animal health. The FDA's action would roll back the approved level of selenium supplementation in animal feeds from 0.3 to 0.1 parts per million in the diet dry matter, to take effect in September 1994. The scientists point out that in some countries like Finland and New Zealand, soil selenium is deficient and fertilizers have been supplemented with selenium for 20 years or more to enable the harvest of crops and forages containing adequate amounts of selenium for normal animal health. Oldfield noted that this practice has not led to environmental problems, even though it adds more selenium than does direct animal use.