Is 1,2,4-Trihydroxybenzene safe in cosmetics?
1,2,4-Trihydroxybenzene has a safety rating of "POOR" in our database. EU status: prohibited. US status: permitted. 8 toxicological study endpoint(s) are available in our database.
1,2,4-Trihydroxybenzene
Also known as: 4-06-00-07338, BRN 2042863, EINECS 208-575-1, Hydroquinone, hydroxy-, Hydroxyquinol (+3 more)
INCI: 1,2,4-TRIHYDROXYBENZENE
1,2,4-Trihydroxybenzene (CAS 533-73-3) is a cosmetic cosmetic ingredient functioning as Hair colorant (auto-oxidative dye). Reported NOAEL =50 mg/kg bw/day (SCCS Opinion); EU Regulation 1223/2009 status: prohibited. Industrial safety data is also available in the chemical safety database. Same-CAS public records also appear in pharmaceutical data.
Function
Hair colorant (auto-oxidative dye)
Editorial assessment
POOR
Preliminary editorial note — not a computed safety verdict.
Regulatory Status
EU EU Status
prohibited
US 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 multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for 1,2,4-Trihydroxybenzene.
Calculate MoS for your specific formulation with the MoS Calculator.
Toxicological Studies
8 study endpoints 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 |
|---|---|---|---|---|---|
| NOAEL | =50 mg/kg bw/day | - | - | NOAEL study | SCCS Opinion |
| NOAEL | =50 mg/kg bw/day | - | - | NOAEL study | SCCS Opinion |
| NOAEL | =50 mg/kg bw/day | - | - | NOAEL study | SCCS Opinion |
| NOAEL | =50 mg/kg bw/day | - | - | NOAEL study | SCCS Opinion |
| NOAEL | =50 mg/kg bw/day | - | - | NOAEL study | SCCS Opinion |
| NOAEL | =50 mg/kg bw/day | - | - | NOAEL study | SCCS Opinion |
| NOAEL | =50 mg/kg bw/day | - | - | NOAEL study | SCCS Opinion |
| NOAEL | =50 mg/kg bw/day | - | - | NOAEL study | SCCS Opinion |
EU CosIng Annex Listing
European Commission CosIng database Annex references per Regulation (EC) No 1223/2009.
Annex II — Prohibited
Ref: 1642
(EU) 2020/1683
Expanded Jurisdictional Detail
Additional regulatory detail beyond the 7-jurisdiction summary: Saudi SFDA, Korea MFDS, ASEAN ACD, Japan/Korea, Brazil/India, and cross-jurisdictional restriction entries.
SA Saudi SFDA (II - Prohibited)
ASEAN Cosmetic Directive (II)
Ref: 1642
JPKR Japan/Korea Cosmetics
Korea (Prohibited): Added 2024; genotoxicity potential
BRIN Brazil/India Cosmetics
India: Prohibited (GNRAS)
Additional Jurisdictional Restrictions (2)
| Jurisdiction | Status | Max % | Product Type |
|---|---|---|---|
| ASEAN | banned | - | All cosmetic products prohibited |
| KR | prohibited | - | - |
Expanded Dermal Absorption Data
Cross-database dermal penetration: EPA Dryad physics-based, Roberts Mendeley permeation, and SCCS-aggregated measured values.
Roberts Skin Permeation (Mendeley 2022)
MW: 126.11
Log Kow: 0.8
Log Kp: -3.9
Log Jmax: -6.240104809313185
Source: Roberts Cheruvu Mendeley 2022
Aggregated DA Values (5 records across 5 sources)
| Type | DA % | Method | Skin Model | SCCS Ref |
|---|---|---|---|---|
| measured | 2.78% | - | - | SCCP/0041 |
| measured | 8.0% | - | - | SCCS/0113 |
| measured | 2.78% | - | - | SCCS/0113 |
| measured | 3.0% | - | - | SCCS/0113 |
| measured | 0.01% | - | - | SCCS/0113 |
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Dye
Editorial summary
Preliminary editorial summary for 1,2,4-Trihydroxybenzene — not a computed safety verdict. See the sourced toxicological data above.
Regulatory Flags
colorant
NOAEL Studies Summary
View details ->Public NOAEL study rows linked to 1,2,4-Trihydroxybenzene by CAS number or substance name.
Studies
8
Lowest NOAEL
50 mg/kg bw/day
Highest NOAEL
50 mg/kg bw/day
SCCS Opinion
Dermal Absorption
View details ->| Absorption % | Method | Vehicle |
|---|---|---|
| 2.78% | - | - |
| 8.0% | - | - |
| 2.78% | - | - |
| 3.0% | - | - |
| 0.01% | - | - |
Known Synonyms
4-06-00-07338
BRN 2042863
EINECS 208-575-1
Hydroquinone, hydroxy-
Hydroxyquinol
Oxyhydroquinone
Oxyhydrochinon
UNII-173O8B04RD
Chemical Function
Dye
Cross-Vertical Safety Context
Same-CAS public records found in pharmaceutical data.
SOURCE
ChEMBL / DrugCentral / FAERS
DB_PHARMA CAS match
Pharmaceutical Data
Same-CAS rows from the pharmaceutical spoke database.
ChEMBL ID
CHEMBL3092389
Frequently Asked Questions
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 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 NOAEL study study via oral route in rat. A total of 8 study endpoints are available. Source: SCCS Opinion.
Is 1,2,4-Trihydroxybenzene used outside cosmetics?
1,2,4-Trihydroxybenzene also appears in pharmaceutical data. The cross-vertical cards on this page render same-CAS public rows from the matched databases.
Compliance Tools
Check 1,2,4-Trihydroxybenzene compliance across multiple jurisdictions:
Ingredient Decoder
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82 Allergen Checker
Check for EU declarable fragrance allergens
Substance Compliance
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MoS Calculator
Calculate Margin of Safety using SCCS methodology
Heavy Metal Limits
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