(a) Conditions The Food and Drug Administration shall not implement or enforce the final rule described in subsection (b) of this section to alter the level of selenium allowed to be used as a supplement in animal diets unless the Commissioner of the Food and Drug Administration makes a determination that
(1) selenium additives are not essential, at levels authorized in the absence of such final rule, to maintain animal nutrition and protect animal health;
(2) selenium at such levels is not safe to the animals consuming the additive;
(3) selenium at such levels is not safe to individuals consuming edible portions of animals that receive the additive;
(4) selenium at such levels does not achieve its intended effect of promoting normal growth and reproduction of livestock and poultry; and
(5) the manufacture and use of selenium at such levels cannot reasonably be controlled by adherence to current good manufacturing practice requirements.