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HC BLUE NO. 17.

Avoid CAS 16517-75-2 / HAIR DYEING

HC Blue No. 17 is a synthetic direct dyeing agent primarily utilized in hair color formulations to impart blue hues. It functions by either adhering to the hair surface for temporary effects or diffusing into the hair shaft for semi-permanent coloration. This ingredient does not possess known active mechanisms for skin improvement or treatment.

Summary

hair dyeing

Science

Mechanism of Action

As a direct hair dyeing agent, HC Blue No. 17 primarily acts by physically adhering to the external surface of the hair in temporary dye applications. For semi-permanent coloration, its small molecular size facilitates diffusion into the hair fiber, imparting color from within. There is no documented mechanism of action that confers beneficial effects directly on the skin.

Research

Clinical Evidence

Insufficient-data confidence
Effective range N/A
Optimal

N/A

Transparency

Dusting Analysis

Not commonly dusted

The Formula

Formulation

Solubility
Water
Optimal pH 7 – 9
0 7 14

Stability

HC Blue No. 17 demonstrates stability when stored appropriately in a cool, dry place, shielded from direct sunlight. However, in buffered aqueous solutions, a notable decomposition of approximately 50% has been observed within an 8-day period. The Scientific Committee on Consumer Safety (SCCS) identified a lack of comprehensive data regarding its stability within typical hair dye formulations.

Conflicts

  • Nitrosating substances (due to the potential for nitrosamine formation)

Safety

Safety Profile

CIR Status
Not reviewed
Max tested
2%
Sensitization risk Unknown

The Scientific Committee on Consumer Safety (SCCS) adopted an opinion on HC Blue 17 in February 2013, noting its use as a hair coloring agent up to 2.0% on-head concentration. As a secondary amine, it carries a risk of nitrosamine formation, therefore it must not be combined with nitrosating substances, and residual nitrosamine content should remain below 50 ppb. While considered not irritant to the skin when applied neat, it is slightly irritant to the eyes. The SCCS could not conclude on its sensitizing potential, citing the highest tested concentration (15% in LLNA) as too low for a definitive assessment. Concerns were also raised about the purity and adequate characterization of various batches used in safety studies. HC Blue No. 17 is regulated in Europe and the the United Kingdom.

Your Skin

Skin Compatibility

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

Our Assessment

Verdict

Avoid

Given its primary function as a hair dyeing agent with no documented skin benefits, coupled with safety concerns regarding potential nitrosamine formation and inconclusive sensitization data, HC Blue No. 17 is not recommended for precision skincare formulations.

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