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Moumoujus

BASIC BROWN 16.

Avoid CAS 26381-41-9 / HAIR DYEING

A synthetic cationic monoazo dye primarily utilized in hair care for non-oxidative, temporary color deposition. Unlike functional skincare actives, its role is purely aesthetic, providing a brown tint that adheres to keratinous surfaces through electrostatic attraction.

Summary

hair colorant cosmetic colorant

Science

Mechanism of Action

This dye functions via its positive (cationic) charge, which creates an electrostatic bond with the negatively charged sites of hair or skin keratin. It primarily coats the exterior surface (cuticle) rather than penetrating deep layers, resulting in surface-level pigment that typically washes out within 1 to 10 cleanses.

Research

Clinical Evidence

Low confidence
Effective range 0.1–2%
Optimal

N/A

Key findings

  1. 01 SCCS/1684/25 (2025): Identified potential for mutagenicity and genotoxicity in non-oxidative formulations at 2%.
  2. 02 SCCP/1165/08 (2008): Classified as a moderate skin sensitizer with a 12.2% EC3 value in LLNA testing.

Transparency

Dusting Analysis

Not commonly dusted
Red flag below
0.1%

Because it is a colorant with zero therapeutic benefit for skin and recent safety concerns regarding DNA integrity, even trace amounts in leave-on skin products are considered unnecessary risks.

The Formula

Formulation

Solubility
Water
Optimal pH 5 – 7
0 7 14

Stability

Optimal stability is achieved in slightly acidic environments. Alkaline conditions (high pH) cause the molecule to lose its cationic charge, leading to precipitation. It is also highly susceptible to UV-induced fading.

Conflicts

  • Anionic surfactants (e.g., Sodium Lauryl Sulfate)
  • Anionic rheology modifiers (e.g., Carbomers)
  • Strong oxidizing agents

Safety

Safety Profile

CIR Status
Safe with restrictions
Max tested
2%
Pregnancy
Caution
Sensitization risk Moderate

While historically permitted at 2%, the 2025 SCCS evaluation concluded it is no longer considered safe at this level due to mutagenic potential. It requires a 48-hour patch test in hair applications.

Your Skin

Skin Compatibility

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

Our Assessment

Verdict

Avoid

Due to its total lack of skincare benefits and recent 2025 safety data highlighting mutagenic risks, Basic Brown 16 is contraindicated for precision skincare.

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