21 C.F.R. § 73.2110
(b) Specifications. The color additive bismuth citrate shall conform to the following specifications and shall be free from impurities other than those named to the extent that those impurities may be avoided by good manufacturing practice:
Bismuth citrate, not less than 97 percent. Mercury (as Hg), not more than 1 part per million. Arsenic (as As), not more than 3 parts per million. Lead (as Pb), not more than 20 parts per million. Volatile matter, not more than 1 percent.
(c) Uses and restrictions. The color additive bismuth citrate may be safely used in cosmetics intended for coloring hair on the scalp, subject to the following restrictions:
(d) Labeling.
(2) The label of a cosmetic containing the color additive bismuth citrate shall bear, in addition to other information required by law, the following statement, conspicuously displayed thereon:
Keep this product out of children's reach. Do not use on cut or abraded scalp. Do not use to color eyelashes, eyebrows, or hair on parts of the body other than the scalp. Wash hands thoroughly after each use.
[43 FR 44831, Sept. 29, 1978, as amended at 75 FR 14493, Mar. 26, 2010]