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Moumoujus

HC RED NO. 7.

Insufficient Data CAS 24905-87-1 / HAIR DYEING

HC Red No. 7 is a synthetic organic dye principally employed as a semi-permanent hair colorant. It imparts a red hue by coating the outer layer of the hair shaft.

Summary

Science

Mechanism of Action

This ingredient functions by depositing its color molecules externally on the hair, providing a superficial, non-penetrative coloring effect. It does not exhibit any known mechanism of action or benefit pertaining to skin physiology.

Research

Clinical Evidence

Insufficient-data confidence
Effective range N/A
Optimal

N/A

Transparency

Dusting Analysis

Not commonly dusted

No specific data is available regarding the dusting characteristics of HC Red No. 7.

The Formula

Formulation

Solubility
Water
Optimal pH N/A
0 7 14

Stability

Aqueous solutions containing 0.5% carboxymethylcellulose, DMSO, and an acetone/olive oil mixture with HC Red No. 7 demonstrated stability within ±11% of their initial concentration after 2 to 4 hours of storage at room temperature, provided they were protected from light and maintained under an inert gas atmosphere. However, stability data within typical hair dye formulations has not been reported.

Conflicts

  • As a secondary amine, HC Red No. 7 is prone to nitrosation, which necessitates careful consideration of potential nitrosamine formation.
  • It may contain 2-nitro-benzene-1,4-diamine as an impurity, which is a carcinogen and prohibited in the EU, though current levels are not deemed a safety concern by the SCCS.

Safety

Safety Profile

CIR Status
Safe with restrictions
Max tested
1%
Sensitization risk Moderate

The Cosmetic Ingredient Review (CIR) Expert Panel has deemed HC Red No. 7 safe for use as a hair dye ingredient under specified conditions and at controlled concentrations, particularly up to 1.0% in non-oxidative hair dyes as affirmed by the SCCS. The FDA also considers 'Red 7' safe in its current applications, with hair dye products containing 'coal tar hair dye' (which encompasses HC Red No. 7) being exempt from certain FDA provisions if labels include mandated caution statements and patch test instructions. Animal studies indicate it is a moderate sensitizer.

Your Skin

Skin Compatibility

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

Our Assessment

Verdict

Insufficient Data

While HC Red No. 7 is a recognized hair colorant with established safety parameters for that application, there is a distinct lack of data regarding its efficacy or direct compatibility for skincare purposes, rendering it an unsuitable ingredient for precision skincare formulations.

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