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Colorant

4-NITROGUAIACOL

CAS 3251-56-7
30

Safety score · 0–100

Caution

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

A nitroaromatic hair-dye chemical. Its chemical class is monitored for genotoxicity and it has not been cleared as a cosmetic colorant in the EU.

4-Nitroguaiacol (4-nitro-2-methoxyphenol, CAS 3251-56-7) is a nitrated phenol used as a direct hair dye intermediate. Nitrophenols as a class are flagged for possible genotoxicity and must pass a substantive SCCS safety review before being listed on EU Cosmetics Regulation Annex IV (permitted colorants); 4-nitroguaiacol is not on that list. Supplier SDS classify the material as a skin and eye irritant. Published cosmetic-specific safety data are sparse, and default-down principles apply. Consumers with hair-dye allergy should assume cross-reactivity with related nitroaniline/nitrophenol class members.

Skin benefits

  • Hair colorant role (yellow/brown)

Known concerns

  • Nitroaromatic class with genotoxicity watch
  • Not on EU Annex IV permitted colorants
  • Skin and eye irritant
  • Limited cosmetic-specific safety dossier

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.