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Moumoujus

2-AMINO-5-NITROPHENOL.

Questionable CAS 121-88-0 / HAIR DYEING

A nitroaniline derivative primarily utilized as a direct-acting colorant and coupling agent in hair dye formulations. This compound demonstrates controlled dermal penetration rates and functions as a mild reducing agent in oxidative coloring systems. While approved for hair care applications, its use in general skincare remains highly restricted due to regulatory limitations.

Summary

hair dyeing colorant coupling agent

Science

Mechanism of Action

Functions as a direct-acting colorant through inherent pigment properties while serving as a coupler in oxidative systems. Acts as a mild reducing agent that can react with hydrogen peroxide and oxidative precursors to form stable pigment complexes within target substrates.

Research

Clinical Evidence

Medium confidence
Effective range 0.5–1.5%
Optimal

1%

Key findings

  1. 01 Demonstrated controlled dermal absorption rate of 13.6% ± 2.9% under oxidative conditions using mini-pig skin models
  2. 02 Two-generation reproductive toxicity study showed no evidence of developmental or reproductive adverse effects

Transparency

Dusting Analysis

Not commonly dusted

Primarily restricted to hair dye applications with specific regulatory concentration limits rather than being used as a dusting ingredient

The Formula

Formulation

Solubility
Both
Optimal pH 5 – 10
0 7 14

Stability

Maintains high stability under inert conditions and darkness. Exhibits slow oxygen reactivity at ambient temperature. Remains stable in crystalline form at pH 5-6 and under alkaline conditions up to pH 10. Temperature sensitivity above 60°C.

Synergies

  • hydrogen peroxide in oxidative systems
  • alkaline pH buffers

Conflicts

  • strong oxidizing agents
  • strong bases
  • acid chlorides
  • acid anhydrides
  • iron compounds above 40ppm

Safety

Safety Profile

CIR Status
Safe as used
Max tested
1.5%
Pregnancy
Safe
Sensitization risk Low

IARC Group 3 classification (not classifiable as carcinogenic). EU and Canadian regulations restrict use to hair dye applications only. Maximum 1.0% in oxidative systems, 0.5% in non-oxidative applications.

Your Skin

Skin Compatibility

Yes Normal
Yes Dry
Yes Oily
No Sensitive
Irritancy Low
Comedogenicity Unknown

Our Assessment

Verdict

Questionable

While demonstrating acceptable safety in hair dye applications, regulatory restrictions and limited skincare relevance make this ingredient unsuitable for precision skincare formulations.

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