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4-(Phenylazo)resorcinol

CAS 2051-85-6
30

Safety score · 0–100

Caution

Derived from EU CosIng regulatory status, PubChem hazard data and published research. How we score.

An azo dye used as a semi-permanent hair and cosmetic colorant with EU restrictions due to concerns about reductive cleavage to aromatic amines.

4-(Phenylazo)resorcinol (Resorcinol Violet) is an azo dye combining resorcinol with a phenylazo group. It is used as a direct dye in semi-permanent hair coloration and cosmetic products. The EU has restricted this substance under Regulation 1223/2009, requiring specific labeling and conditions of use due to the potential for reductive cleavage of the azo bond, releasing aromatic amines that may be carcinogenic. It remains permitted in hair dye formulations under specific restrictions.

Skin benefits

  • Provides violet-purple direct dye coloration
  • Used in semi-permanent hair color formulations

Known concerns

  • EU restricted hair dye substance
  • Azo bond - potential for reductive cleavage to aromatic amines
  • Skin sensitization risk
  • Must not be used for eyebrows and eyelashes in EU

References

EU

EU CosIng database

European Commission cosmetic ingredient registry: regulatory status, restrictions, authorised functions.

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This profile is for educational purposes and does not constitute medical advice. Regulatory status and scientific understanding evolve, so always read the physical product label and consult a healthcare professional for personal concerns.