Yellow prussiate of soda (sodium ferrocyanide decahydrate: Na4Fe(Cn)6°-10H2O) may be safely used as an anticaking agent in salt for animal consumption at a level not to exceed 13 parts per million. The additive contains a minimum of 99.0 percent by weight of sodium ferrocyanide decahydrate.
21 C.F.R. §573.1020