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Moumoujus

HC BLUE NO. 16.

Avoid CAS 502453-61-4 / HAIR DYEING

HC Blue No. 16 is a synthetic semi-permanent hair dye that functions by non-covalently binding to keratin fibers. While primarily a colorant for hair, its substantial molecular size restricts significant dermal absorption, with in vitro models indicating less than 0.1% systemic bioavailability.

Summary

Science

Mechanism of Action

As a colorant, HC Blue No. 16 interacts with keratin fibers via non-covalent bonds, a mechanism primarily relevant for hair dyeing. For topical skin application, its large molecular structure results in minimal dermal penetration, with less than 0.1% systemic bioavailability demonstrated in in vitro studies.

Research

Clinical Evidence

Low confidence
Effective range N/A
Optimal

N/A

Transparency

Dusting Analysis

Not commonly dusted

The Formula

Formulation

Solubility
Water
Optimal pH N/A
0 7 14

Stability

HC Blue No. 16 demonstrates high water solubility (218 g/L at 20°C, pH 5.6) and maintains homogeneity in aqueous solutions for up to 4 hours. Critical stability considerations include its potential to form carcinogenic nitrosamines via nitrosation, especially in the presence of nitrosating agents.

Conflicts

  • Nitrosating agents

Safety

Safety Profile

CIR Status
Not reviewed
Max tested
3%
Sensitization risk Moderate

The SCCS deemed HC Blue No. 16 safe for use as a non-oxidative hair dye at a maximum on-head concentration of 3.0% in 2012; however, it has not been reviewed by CIR. A significant concern is its nature as a secondary amine, which confers a potential risk for the formation of carcinogenic nitrosamines under specific conditions. Furthermore, PubChem classifies this ingredient as harmful if swallowed and a cause of skin and serious eye irritation.

Your Skin

Skin Compatibility

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

Our Assessment

Verdict

Avoid

Given its primary role as a hair dye, lack of documented skincare benefits, and significant safety concerns including potential for carcinogenic nitrosamine formation and noted irritancy, HC Blue No. 16 is not suitable for precision skincare formulations.

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