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Moumoujus

1,5-NAPHTHALENEDIOL.

Avoid CAS 83-56-7 / HAIR DYEING

1,5-Naphthalenediol is an organic compound primarily recognized as a precursor in oxidative hair dye formulations. Despite its historical use in hair colorants, this ingredient is currently prohibited for use in cosmetic products within major global markets due to significant safety concerns related to skin sensitization and ocular irritation.

Summary

Science

Mechanism of Action

In hair dye applications, 1,5-Naphthalenediol functions as a precursor that reacts with primary intermediates to form the final dye-stuff. This chemical reaction is typically accelerated by an oxidizing agent, such as hydrogen peroxide, to facilitate color development.

Research

Clinical Evidence

Insufficient-data confidence
Effective range N/A
Optimal

N/A

Transparency

Dusting Analysis

Not commonly dusted

This ingredient is not commonly used in skincare formulations due to significant safety concerns and regulatory prohibitions, making 'dusting' an irrelevant concept for its profile.

The Formula

Formulation

Solubility
Oil
Optimal pH N/A
0 7 14

Stability

The substance is generally stable under recommended storage conditions. While no specific optimal pH range for formulation stability has been identified, a 0.5g/l aqueous solution at 20℃ exhibits a pH of approximately 6. Standard solutions in Tetrahydrofuran demonstrated stability for at least 46 hours, with chromatographic system solutions stable for a minimum of 4.6 hours at room temperature in the dark.

Conflicts

  • Strong oxidizing agents
  • Strong bases

Safety

Safety Profile

CIR Status
Not reviewed
Max tested
1%
Sensitization risk Moderate

1,5-Naphthalenediol has been identified as a moderate skin sensitizer, with an EC3 value of 3.4% in a Local Lymph Node Assay. The Scientific Committee on Consumer Safety (SCCS) issued an opinion in 2010 (SCCS/1365/10) confirming its sensitizing properties and highlighting the need for further genotoxicity/mutagenicity studies in finished hair dye formulations. Despite an earlier 1998 opinion suggesting no hazard at 1% in hair dye formulations (0.5% upon application), subsequent assessments, including a 2007 opinion, deemed the information insufficient for a conclusive risk assessment. It is classified as an ocular irritant and may cause an allergic skin reaction (H317). Due to these concerns, 1,5-Naphthalenediol is prohibited for use in cosmetics within the European Union, ASEAN, and New Zealand.

Your Skin

Skin Compatibility

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

Our Assessment

Verdict

Avoid

1,5-Naphthalenediol should be actively avoided in cosmetic formulations due to its classification as a moderate skin sensitizer and ocular irritant, leading to its prohibition in major global cosmetic markets.

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