Hair Dye
ISATIN
Safety score · 0–100
Moderate
Derived from EU CosIng regulatory status, PubChem hazard data and published research. How we score.
About
A reactive indole-2,3-dione used as a hair-dye intermediate. Concentration-limited in cosmetic use with genotoxicity signals to watch.
Isatin (CAS 91-56-5, 1H-indole-2,3-dione) is a naturally occurring compound from Isatis tinctoria (woad) and related plants, also made synthetically. In cosmetics it is used as a hair-dye intermediate that couples with amines to form indigoid dye structures. It contains a reactive alpha,beta-dicarbonyl system that gives positive signals in some in vitro genotoxicity assays; SCCS and equivalent bodies have reviewed it and applied concentration limits in hair-dye applications. No long-term human data. Not CMR-classified. Score lands in Moderate/orange — functional and regulatorily accepted with limits, but the reactive chemistry keeps it out of the yellow band.
Function
Skin benefits
- Natural indigo-style hair dye intermediate
- Alternative to PPD oxidative couplers
- Concentration-limited safe use under SCCS
Known concerns
- Reactive dicarbonyl — genotoxicity signals in some assays
- SCCS concentration limits
- Staining
- Limited long-term safety data
References
EU CosIng database
European Commission cosmetic ingredient registry — regulatory status, restrictions, authorised functions.
Related hair dyes
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This profile is for educational purposes and does not constitute medical advice. Regulatory status and scientific understanding evolve — always read the physical product label and consult a healthcare professional for personal concerns.