Poor Cosmetic Ingredient NOAEL Data

1,2,4-Trihydroxybenzene

INCI: 1,2,4-TRIHYDROXYBENZENE

CAS Number

533-73-3

Function

Hair colorant (auto-oxidative dye)

Safety Rating

POOR

Regulatory Status

🇪🇺 EU Status prohibited

🇺🇸 US Status permitted

US Notes Permitted as coal tar hair dye with mandatory caution statement and patch test instructions per FD&C Act; CIR Panel concluded safe as hair dye at current use (up to 2.5%)

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

Safety Data

Margin of Safety (MoS)

adequate

Dermal Absorption

negligible

Sensitization

moderate

Calculate MoS for your specific formulation with the MoS Calculator.

Toxicological Studies

1 study endpoint found for 1,2,4-Trihydroxybenzene. 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

Expert Verdict

Genotoxic in vitro (mutagenic in Ames tests, DNA strand breaks, SCE); generates ROS and hydrogen peroxide via auto-oxidation; benzene metabolite; SCCS concluded unsafe due to genotoxicity

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Concern Level: High

Regulatory Flags

colorant

Frequently Asked Questions

Is 1,2,4-Trihydroxybenzene safe in cosmetics?

Genotoxic in vitro (mutagenic in Ames tests, DNA strand breaks, SCE); generates ROS and hydrogen peroxide via auto-oxidation; benzene metabolite; SCCS concluded unsafe due to genotoxicity The EU classifies 1,2,4-Trihydroxybenzene as "prohibited". Safety rating: POOR. 1 toxicological study endpoint(s) are available in our database.

Is 1,2,4-Trihydroxybenzene allowed in the EU?

1,2,4-Trihydroxybenzene EU regulatory status: prohibited. This is based on EU Regulation 1223/2009 and its amendments.

What does 1,2,4-Trihydroxybenzene do in cosmetics?

1,2,4-Trihydroxybenzene functions as: Hair colorant (auto-oxidative dye). It is classified as a cosmetic ingredient in our database. CAS number: 533-73-3.

What is the Margin of Safety for 1,2,4-Trihydroxybenzene?

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 1,2,4-Trihydroxybenzene?

The NOAEL (No Observed Adverse Effect Level) for 1,2,4-Trihydroxybenzene is 50 mg/kg bw/day based on a Subchronic study via oral route in rat. Source: COSMOS_DB.

Compliance Tools

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Substance Compliance

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MoS Calculator

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