21 CFR § 573.340
Diatomaceous earth
June 25, 2020
(a) Identity. The additive consists of siliceous skeletal material derived from various species of diatoms.
(b) Specifications. The additive shall conform to the following specifications:
Lead, not more than 15 parts per million.
Arsenic (as As), not more than 20 parts per million
Fluorine, not more than 600 parts per million.
(c) Uses. It is used or intended for use as an inert carrier or anticaking agent in animal feeds in an amount not to exceed 2 percent by weight of the total ration.