Also known as: 1,4-Benzenediol, Dihydroxybenzene, Benzene, p-dihydroxy-, Black and White Bleaching Cream, Derma-Blanch (+14 more)
CAS 123-31-9
Hydroquinone (CAS 123-31-9) is a chemical substance with GHS signal word Danger; key hazard signal: H351; H341; H302; H318; H317; H400. Key regulatory status: REACH registered, 13 regulatory/inventory lists, cosmetic ingredient cross-reference; source data from ECHA CLP, EPA ToxValDB, EPA CPDat, AICIS, IARC, ECHA REACH, ILO ICSC, OSHA, EPA TRI.
Hydroquinone is prohibited in EU cosmetics but has active industrial GHS classifications (H351, H341, H302, H318, H317, H400).
CAS, identifiers, formula, and alternate names for the matched substance record.
Carcinogenic hazard classification from IARC monograph evaluations.
| Group | Meaning | Evaluated | Volume |
|---|---|---|---|
| Group 3 | Not classifiable | 1998 | 15, Sup 7, 71 |
EU harmonized hazard classification, hazard statements, pictograms, and signal word.
| Hazard Class | H-Statements | Pictograms | Signal |
|---|---|---|---|
| Carc. 2; Muta. 2; Acute Tox. 4 *; Eye Dam. 1; Skin Sens. 1; Aquatic Acute 1 | H351; H341; H302; H318; H317; H400 | GHS08; GHS07; GHS05; GHS09 | Danger |
International Chemical Safety Card hazard and exposure summary.
| Field | Value |
|---|---|
| Short-term Effects | The substance is severely irritating to the eyes. The substance is irritating to the skin and respiratory tract. |
| Long-term Effects | Repeated or prolonged contact with skin may cause dermatitis. Repeated or prolonged contact may cause skin sensitization. The substance may have effects on the eyes and skin. This may result in discolouration of the conjunctiva and cornea and skin depigmentation. This substance is possibly carcinogenic to humans. |
| Routes of Exposure | The substance can be absorbed into the body by inhalation, through the skin and by ingestion. |
Occupational exposure limits from OSHA, NIOSH, and ACGIH rows.
| Agency | Metric | Value | ppm | mg/m3 | Skin |
|---|---|---|---|---|---|
| OSHA | TWA | 2 mg/m³ | - | 2 | N |
| NIOSH | CEILING | 2 mg/m³ [15 minutes] | - | 2 | N |
| ACGIH | TWA | 1 mg/m³ [2007] | - | 1 | N |
| CAL/OSHA | TWA | 2 mg/m³ | - | 2 | N |
| NIOSH | IDLH | 50 mg/m³ | - | 50 | - |
Industrial and product-use categories associated with this substance.
Inventory, screening, and regulatory list matches from public chemical databases.
| List | Keyword | Source |
|---|---|---|
| banned; Europe; Personal care | European Commission | CosIng |
| CEDI | FDA | United States Food and Drug Administration (FDA) |
| Indirect additives food contact (10/2018) | FDA | United States Food and Drug Administration (FDA) |
| Australia; Food and drug - smoking-related products | New Zealand ESR | CPCat |
| Europe; Personal care; restricted | European Commission | CosIng |
| Canada; pharmaceutical | DrugBank | DrugBank |
| Canada; pharmaceutical | DrugBank | DrugBank |
| - | Danish Environmental Protection Agency | Danish EPA |
| Personal care; Southeast Asia | Asean | ASEAN Cosmetics |
| Europe; Food contact items; Toys and children's products | Danish EPA | Danish EPA |
| Europe | European Commission | Fl@vis |
| inert_ingredient; non_food_use; Pesticides | EPA | CPCat |
| drinking_water; Europe; manufacturing; plastic_additive | Belgaqua | CPCat |
Toxicology endpoints rendered from public NOAEL study rows.
| Value | Unit | Endpoint | Route | Species | Source |
|---|---|---|---|---|---|
| 2.643 | ug/mL | CD54, EC200 | Dermal | - | NTP ICE skin sensitization |
| 2.89 | ug/mL | CD54, EC200 | Dermal | - | NTP ICE skin sensitization |
| 6.9 | ug/mL | CD54, EC200 | Dermal | - | NTP ICE skin sensitization |
| 0.3 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 0.57 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 1.331 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 1.4 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 2.1 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 2.124 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 2.13 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 3.6 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| <4.3 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 5.6 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 6.3 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| <7.9 | ug/mL | CD86, EC150 | Dermal | - | NTP ICE skin sensitization |
| 5.52 | ug/mL | CV70 | Dermal | - | NTP ICE skin sensitization |
| 5 | ug/mL | CV75 | Dermal | - | NTP ICE skin sensitization |
| 6 | ug/mL | CV75 | Dermal | - | NTP ICE skin sensitization |
| 9.5 | ug/mL | CV75 | Dermal | - | NTP ICE skin sensitization |
| 12.7 | ug/mL | CV75 | Dermal | - | NTP ICE skin sensitization |
| 23.6 | ug/mL | CV75 | Dermal | - | NTP ICE skin sensitization |
| 44 | ug/mL | CV75 | Dermal | - | NTP ICE skin sensitization |
| =2.1 | mg/m3 | DNEL systemic | inhalation | Human | ToxValDB GESTIS DNEL |
| 83.3 | % | Depletion Cys | Dermal | - | NTP ICE skin sensitization |
| 99.6 | % | Depletion Cys | Dermal | - | NTP ICE skin sensitization |
| 51.1 | % | Depletion Lys | Dermal | - | NTP ICE skin sensitization |
| 53.7 | % | Depletion Lys | Dermal | - | NTP ICE skin sensitization |
| 67.2 | % | Depletion Lys + Cys | Dermal | - | NTP ICE skin sensitization |
| 77 | % | Depletion Lys + Cys | Dermal | - | NTP ICE skin sensitization |
| 9.797 | uM | EC1.5 | Dermal | - | NTP ICE skin sensitization |
| 0.07 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 0.08 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 0.1 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 0.11 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 0.19 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 0.23 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 0.33 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 0.37 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 1.34 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 1.67 | % | EC3 | Dermal | Mouse | NTP ICE skin sensitization |
| 51.29 | uM | EC3 | Dermal | - | NTP ICE skin sensitization |
| XV74C1N1AE | UNII | FDA UNII substance identifier | - | - | openFDA substances |
| XV74C1N1AE | UNII | FDA UNII substance identifier | - | - | openFDA substances |
| XV74C1N1AE | UNII | FDA UNII substance identifier | - | - | openFDA substances |
| XV74C1N1AE | UNII | FDA UNII substance identifier | - | - | openFDA substances |
| 3 | IARC group | IARC carcinogenicity classification | - | - | IARC Monographs |
| 3 | IARC group | IARC carcinogenicity classification | - | - | IARC Monographs |
| 3 | IARC group | IARC carcinogenicity classification | - | - | IARC Monographs |
| 3 | unitless | IARC group | - | - | NTP ICE cancer |
| 130.7 | uM | IC50 | Dermal | - | NTP ICE skin sensitization |
Showing 50 of 100 studies
Registration status from the ECHA REACH registered substances database.
| Status | Name | EC Number | Link |
|---|---|---|---|
| Registered | Hydroquinone | 204-617-8 | ECHA overview → |
TRI hazard and reporting flags for the matched chemical.
| Chemical | Category | Flags |
|---|---|---|
| Hydroquinone | - | - |
Australian industrial chemicals inventory status and applicable conditions.
Same-CAS cosmetic ingredient record for cross-vertical context.
Same-CAS pharmaceutical records from drug and bioactivity sources.
Same-CAS cannabis compliance and lab records where available.
1 cannabis record found in efsa substances.
View full cannabis profile →Hydroquinone (CAS 123-31-9) is classified under EU CLP Annex VI as Carc. 2; Muta. 2; Acute Tox. 4 *; Eye Dam. 1; Skin Sens. 1; Aquatic Acute 1 with signal word Danger. Hazard statements: H351; H341; H302; H318; H317; H400. Source: EU CLP Annex VI (ECHA).
Hydroquinone has 100 NOAEL studies in the database. The lowest reported value is 0.07 % via Dermal in Mouse. Source: NTP ICE skin sensitization.
Hydroquinone appears on 11 regulatory/inventory lists including banned; Europe; Personal care, CEDI, Indirect additives food contact (10/2018), and 8 more. Source: EPA CPDat.
Hydroquinone is classified by IARC as Group 3 — not classifiable as to its carcinogenicity to humans (evaluated 1998). Source: IARC Monographs on the Identification of Carcinogenic Hazards to Humans.
Occupational exposure limits for Hydroquinone are set by OSHA, NIOSH, ACGIH. 5 limit values from official agencies are documented in the database. Source: OSHA, NIOSH, ACGIH.
Yes, Hydroquinone is also indexed as a cosmetic ingredient under the name Hydroquinone. View the full cosmetic safety profile on the ingredient page for detailed safety data, SCCS opinions, and regulatory status.
Safety data is sourced from ECHA CLP Annex VI, EPA ToxValDB, EPA CPDat, AICIS (Australian Industrial Chemicals Introduction Scheme), EPA DSSTox, IARC Monographs, ECHA REACH, ILO/WHO ICSC, OSHA/NIOSH/ACGIH, EPA Toxics Release Inventory, CosIng / Ingredients DB, ChEMBL / DailyMed, cannabis regulatory/lab databases. All data traces to primary regulatory sources and is updated from official government databases.
Hydroquinone is prohibited in EU cosmetics but has active industrial GHS classifications (H351, H341, H302, H318, H317, H400).
Hydroquinone also appears in cosmetics, pharmaceutical, cannabis databases.