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Colorant

Sodium 4-[(2-Hydroxy-1-naphthyl)azo]naphthalenesulphonate

CAS 1658-56-6
50

Safety score · 0–100

Moderate

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

A naphthalene-azo sulfonate red colorant — used in some rinse-off cosmetic products with EU restrictions. Azo bonds carry aromatic-amine impurity and sensitization concerns; sits in moderate-caution territory.

Skin benefits

  • Vibrant red colorant
  • Stable in cosmetic bases

Known concerns

  • Azo dye — potential aromatic-amine impurities
  • EU restricts to rinse-off / specific uses
  • Possible sensitization

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.