4-[(4-Ethoxyphenyl)azo]naphthol
Safety score · 0–100
Caution
Derived from EU CosIng regulatory status, PubChem hazard data and published research. How we score.
About
An azo dye compound used in semi-permanent hair color formulations, with EU restrictions due to concerns about mucous membrane contact.
4-[(4-Ethoxyphenyl)azo]naphthol is an azo compound combining a naphthol chromophore with an ethoxyphenyl group via an azo linkage. The EU Cosmetics Regulation 1223/2009 restricts this substance, specifying it is not to be used in products applied on mucous membranes, indicating specific concerns about systemic absorption or local toxicity in sensitive epithelial tissues. Azo dyes can potentially cleave to release aromatic amines under certain conditions.
Skin benefits
- Provides semi-permanent color to hair
Known concerns
- EU restriction - not permitted in mucous membrane products
- Azo dye - potential cleavage to aromatic amines under reductive conditions
- Skin sensitization possible
References
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 — always read the physical product label and consult a healthcare professional for personal concerns.