21 C.F.R. § 73.2180 – Guaiazulene.

(a) Identity.
1. (1) The color additive, guaiazulene, is principally 1,4-dimethyl-7-isopropyl-azulene.
2. (2) Color additive mixtures of guaiazulene for cosmetic use may contain the following diluent:
  Polyethylene glycol-40 castor oil (PEG-40 castor oil). Saponification No., 60 to 70. Hydroxyl No., 63 to 78. Acid No., 2. Specific gravity, 1.05 to 1.07.
(b) Specifications. Guaiazulene shall conform to the following specifications and shall be free from impurities, other than those named, to the extent that such other impurities may be avoided by good manufacturing practice.
Melting point, 30.5 °C to 31.5 °C. Lead (as Pb), not more than 20 parts per million. Arsenic (as As), not more than 3 parts per million. Mercury (as Hg), not more than 1 part per million. Total color, not less than 99 percent.
(c) Uses and restrictions. Guaiazulene may be safely used in externally applied cosmetics in amounts consistent with good manufacturing practice.
(d) Labeling. The label of the color additive and any mixtures prepared therefrom intended solely or in part for coloring purposes shall conform to the requirements of § 70.25 of this chapter.
(e) Exemption from certification. Certification of this color additive for the prescribed use is not necessary for the protection of the public health and therefore batches thereof are exempt from the certification requirements of section 721(c) of the act.