Science
Mechanism of Action
Functions as a primary intermediate in oxidative hair dyeing systems by undergoing alkaline oxidation to form quinone diimine intermediates, which subsequently react with coupling agents to generate large indoaniline dye molecules that become permanently trapped within the hair shaft structure.
Research
Clinical Evidence
Medium confidence0.6%
Key findings
- 01 NTP bioassay at 0.3-0.6% showed no carcinogenicity evidence in rats, though noted dose-dependent liver tumor association in male mice
- 02 Safety evaluation at 2.5% demonstrated minimal ocular irritation (mild conjunctival inflammation) and no skin irritation in controlled conditions
Transparency
Dusting Analysis
Not applicable for skincare formulations as this ingredient is restricted to hair dye applications only
The Formula
Formulation
Stability
Exhibits extreme instability when exposed to air and light, rapidly oxidizing to purple then black coloration; requires storage under inert atmosphere and immediate mixing with peroxide before application
Synergies
- hydrogen peroxide
- alkaline activators
- coupling agents
Conflicts
- oxidizing agents
- strong acids
- oxygen exposure
- light exposure
Safety
Safety Profile
CIR approved for hair dye use under 1.0% but prohibited for eyelash/eyebrow applications and dermal coloring; EU SCCS banned this derivative in 2013 due to insufficient genotoxicity safety data
Your Skin
Skin Compatibility
Our Assessment
Verdict
Restricted hair dye ingredient with regulatory bans and safety concerns that has no place in modern precision skincare formulations.
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References
Sources