21 C.F.R. § 73.2250 – Iron oxides.

(a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including the hydrated forms. It is free from admixture with other substances.
(b) Specifications. Iron oxides shall conform to the following specifications, all on an “as is” basis:
Arsenic (as As), not more than 3 parts per million. Lead (as Pb), not more than 10 parts per million. Mercury (as Hg), not more than 3 parts per million.
(c) Uses and restrictions. Iron oxides are safe for use in coloring cosmetics generally, including cosmetics applied to the area of the eye, in amounts consistent with good manufacturing practice.
(d) Labeling. The color additive and any mixture prepared therefrom intended solely or in part for coloring purposes shall bear, in addition to any information required by law, labeling in accordance with § 70.25 of this chapter.
(e) Exemption from certification. Certification of this color additive is not necessary for the protection of the public health, and therefore batches thereof are exempt from certification pursuant to section 721(c) of the act.