1-Naphthol and its salts
Safety score · 0–100
Caution
Derived from EU CosIng regulatory status, PubChem hazard data and published research. How we score.
About
A naphthol (hydroxynaphthalene) hair dye intermediate restricted under EU Annex II due to carcinogenic classification. The phenolic naphthalene structure and diazotization capability for azo dye formation raise significant safety concerns.
1-Naphthol and its salts are listed in EU Annex II (reference 1329) of the Cosmetics Regulation as substances prohibited in cosmetic products. 1-Naphthol is a key intermediate for azo dye synthesis and is itself classified as carcinogenic (H351) under EU CLP regulation. The phenolic hydroxyl group on the naphthalene ring enables diazotization and coupling reactions used in hair dyeing. The Annex II listing means this compound and its salts are prohibited from use in cosmetic products within the EU, regardless of concentration.
Known concerns
- EU Annex II prohibited substance (reference 1329)
- Carcinogenicity concern (H351)
- Used as hair dye intermediate - prohibited in EU cosmetics
- Metabolic activation to reactive intermediates 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.