Moderate Cosmetic Ingredient NOAEL Data GHS Classified

1,5-Naphthalenediol

INCI: 1,5-NAPHTHALENEDIOL

CAS Number
83-56-7
Function
Hair dye precursor/coupler — reacts with primary intermediates under oxidative conditions to form final dye
Safety Rating
MODERATE

Regulatory Status

🇪🇺 EU Status prohibited
EU Max Conc. 1.0%
🇺🇸 US Status permitted
US Notes Permitted under coal tar hair dye exemption (21 CFR 73/74); subject to FDA caution labeling requirements

For full compliance data across 55 jurisdictions, use the Substance Compliance tool.

Safety Data

Margin of Safety (MoS)
adequate
Dermal Absorption
low
Sensitization
moderate

Calculate MoS for your specific formulation with the MoS Calculator.

Toxicological Studies

1 study endpoint found for 1,5-Naphthalenediol. NOAEL (No Observed Adverse Effect Level) values are used to calculate the Margin of Safety per SCCS methodology.

Endpoint Value Route Species Study Type Source
LOAEL 50 mg/kg bw/day oral rat Subchronic COSMOS_DB

GHS Hazard Classification

Globally Harmonized System classification per ECHA C&L inventory and ILO/WHO International Chemical Safety Cards.

Short-term Exposure Effects
The substance is mildly irritating to the eyes.
Routes of Exposure
The substance can be absorbed into the body by ingestion.

Expert Verdict

Clastogenic in vitro (chromosomal aberrations in V79 cells, OECD 473) with negative in vivo micronucleus test. Eye irritant causing conjunctival redness and chemosis in rabbits. Kidney pigmentation observed at ≥100 mg/kg oral in rats. Log P = 1.70.

⚠️
Concern Level: Moderate

Regulatory Flags

eu_cosing_listed

Frequently Asked Questions

Is 1,5-Naphthalenediol safe in cosmetics?

Clastogenic in vitro (chromosomal aberrations in V79 cells, OECD 473) with negative in vivo micronucleus test. Eye irritant causing conjunctival redness and chemosis in rabbits. Kidney pigmentation observed at ≥100 mg/kg oral in rats. Log P = 1.70. The EU classifies 1,5-Naphthalenediol as "prohibited". Safety rating: MODERATE. 1 toxicological study endpoint(s) are available in our database.

Is 1,5-Naphthalenediol allowed in the EU?

1,5-Naphthalenediol EU regulatory status: prohibited. Maximum allowed concentration: 1.0%. This is based on EU Regulation 1223/2009 and its amendments.

What does 1,5-Naphthalenediol do in cosmetics?

1,5-Naphthalenediol functions as: Hair dye precursor/coupler — reacts with primary intermediates under oxidative conditions to form final dye. It is classified as a cosmetic ingredient in our database. CAS number: 83-56-7.

What is the Margin of Safety for 1,5-Naphthalenediol?

adequate The Margin of Safety (MoS) is calculated using SCCS methodology. A MoS above 100 is generally considered safe. Use the MoS Calculator tool to calculate MoS for your specific formulation and product category.

What is the NOAEL for 1,5-Naphthalenediol?

The NOAEL (No Observed Adverse Effect Level) for 1,5-Naphthalenediol is 50 mg/kg bw/day based on a Subchronic study via oral route in rat. Source: COSMOS_DB.

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