Moderate Cosmetic Ingredient NOAEL Data Sensitization Data

4-Amino-2-Hydroxytoluene

INCI: 4-AMINO-2-HYDROXYTOLUENE

CAS Number
2835-99-6
Function
Hair dyeing (oxidative hair dye coupler)
Safety Rating
MODERATE

Regulatory Status

🇪🇺 EU Status prohibited
🇺🇸 US Status permitted
US Notes Permitted under coal tar hair dye exemption (21 USC §361(a)); CIR concluded safe for use as a hair dye ingredient at current practices of use and concentration

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

Safety Data

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

Calculate MoS for your specific formulation with the MoS Calculator.

Toxicological Studies

2 study endpoints found for 4-Amino-2-Hydroxytoluene. 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
NOAEL 60 mg/kg bw/day oral rat Subchronic COSMOS_DB
LOAEL 120 mg/kg bw/day oral rat Subchronic COSMOS_DB

Sensitization Profile

Contact sensitization data for 4-Amino-2-Hydroxytoluene based on clinical patch test studies and IFRA standards.

Sensitization Rate
low
Allergen Class
dye
EU Allergen Listed
no
Patch Test Positive Rate
0.5%
Cross-reactivity Group
para-amino-group
Reaction Type
contact-dermatitis

Source: IVDK; NACDG; ESSCA

Expert Verdict

Must not be used with nitrosating agents. Mandatory consumer warning: Hair colorants can cause severe allergic reactions. Not intended for persons under 16. Patch test recommended before each use.

⚠️
Concern Level: Moderate

Regulatory Flags

eu_cosing_listed

Frequently Asked Questions

Is 4-Amino-2-Hydroxytoluene safe in cosmetics?

Must not be used with nitrosating agents. Mandatory consumer warning: Hair colorants can cause severe allergic reactions. Not intended for persons under 16. Patch test recommended before each use. The EU classifies 4-Amino-2-Hydroxytoluene as "prohibited". Safety rating: MODERATE. 2 toxicological study endpoint(s) are available in our database.

Is 4-Amino-2-Hydroxytoluene allowed in the EU?

4-Amino-2-Hydroxytoluene EU regulatory status: prohibited. This is based on EU Regulation 1223/2009 and its amendments.

What does 4-Amino-2-Hydroxytoluene do in cosmetics?

4-Amino-2-Hydroxytoluene functions as: Hair dyeing (oxidative hair dye coupler). It is classified as a cosmetic ingredient in our database. CAS number: 2835-99-6.

What is the Margin of Safety for 4-Amino-2-Hydroxytoluene?

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 4-Amino-2-Hydroxytoluene?

The NOAEL (No Observed Adverse Effect Level) for 4-Amino-2-Hydroxytoluene is 60 mg/kg bw/day based on a Subchronic study via oral route in rat. A total of 2 study endpoints are available. Source: COSMOS_DB.

Compliance Tools

Check 4-Amino-2-Hydroxytoluene compliance across multiple jurisdictions:

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Substance Compliance
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MoS Calculator
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