3-Imidazol-4-ylacrylic acid (Urocanic acid) and its ethyl ester
The consolidated GB Cosmetics Regulation lists this record in Annex II.
Regulatory decision and full conditions
- Status
- Prohibited
- Legal role
- Binding rule
- Regulatory summary
- The consolidated GB Cosmetics Regulation lists this record in Annex II.
- Conditions and restrictions
- A prohibition entry may contain no separate condition text because the regulatory outcome is the prohibition itself. Open the cited source and apply the market-wide requirements below.
Substance identity
- Official source name
- 3-Imidazol-4-ylacrylic acid (Urocanic acid) and its ethyl ester
- CAS
- 104-98-3; 27538-35-8
- EC
- 203-258-4; 248-515-1
- Identity mapping
- cas_number
- Linked ingredient
- UROCANIC ACID
Linked CosIng identity data
Names and aliases
CosIng description: 2-Propenoic acid, 3-(1H-imidazol-4-yl)-
EU inventory restriction note: II/418
Recorded cosmetic function: UV ABSORBER
Function pages:UV ABSORBER
View the complete ingredient profileCross-market snapshot for this identity
Exact linked records currently present in this site. An absent market means no imported exact match, not permission to use the substance.
European Union
1 linked record
Open supporting recordGreat Britain
Current record1 linked record
Open supporting recordCanada
1 linked record · 1 with specific conditions
Open supporting recordNew Zealand
2 linked records
Open supporting recordASEAN
1 linked record
Open supporting recordChina
1 linked record · 1 with specific conditions
Open supporting recordSouth Korea
1 linked record · 1 with specific conditions
Open supporting recordBrazil
1 linked record · 1 with specific conditions
Open supporting recordIndia
1 linked record · 1 with specific conditions
Open supporting recordSaudi Arabia
1 linked record
Open supporting recordVerified chemistry for CAS 104-98-3
Urocanic Acid
- IUPAC name
- (E)-3-(1H-imidazol-5-yl)prop-2-enoic acid
- Molecular formula
- C6H6N2O2
- Molecular weight
- 138.12 g/mol
- Exact mass
- 138.042927438 Da
- Monoisotopic mass
- 138.042927438 Da
- XLogP3
- 0.0
- Topological polar surface area
- 66.0 Ų
- Molecular complexity
- 156.0
- Formal charge
- 0
- Hydrogen-bond donors
- 2
- Hydrogen-bond acceptors
- 3
- Rotatable bonds
- 2
- Heavy atoms
- 10
- Covalent units
- 1
Names and synonyms reported to PubChem
16 more reported names
External database identifiers
- ChEBI:CHEBI:27248
- ChEBI:CHEBI:30817
- ChEMBL:CHEMBL1236602
- EPA DTXSID:DTXSID5041148
- PubMed:24061166
- PubMed:15337293
- PubMed:14617103
Advanced structure statistics
- Defined atom stereocentres
- 0
- Undefined atom stereocentres
- 0
- Defined bond stereocentres
- 1
- Undefined bond stereocentres
- 0
- 3D pharmacophore features
- 6
- 3D rings
- 1
- 3D hydrophobes
- 0
- 3D acceptor features
- 2
- 3D donor features
- 1
- 3D anionic centres
- 1
- 3D cationic centres
- 1
- 3D conformers
- 6
- Effective 3D rotors
- 2.0
Machine-readable structure identifiers
- SMILES
C1=C(NC=N1)/C=C/C(=O)O- InChI
InChI=1S/C6H6N2O2/c9-6(10)2-1-5-3-7-4-8-5/h1-4H,(H,7,8)(H,9,10)/b2-1+- InChIKey
LOIYMIARKYCTBW-OWOJBTEDSA-N
Evidence from additional scientific databases
NIH PubChem PUG-View
Attributed physical-property, hazard, environmental and use annotations.
- Melting Point: 225 °C Source: DrugBank
- Melting Point: 225 °C Source: Human Metabolome Database (HMDB)
- Physical Description: Solid Source: Human Metabolome Database (HMDB)
- Solubility: 1500 mg/L (at 17 °C) Source: DrugBank
- Solubility: 1.5 mg/mL at 17 °C Source: Human Metabolome Database (HMDB)
- Cosmetic Ingredient Review Conclusion: The safety of this ingredient has not been documented and substantiated. The CIR Expert Panel cannot conclude whether Urocanic Acid is safe for use in cosmetic products until such time as the appropriate safety data have been obtained and evaluated. Source: Cosmetic Ingredient Review (CIR)
- Cosmetic Ingredient Review Finding(s): Ingredients for which the data are insufficient and their use in cosmetics is not supported Source: Cosmetic Ingredient Review (CIR)
- Cosmetic Ingredient Review Link: CIR ingredient: Urocanic Acid Source: Cosmetic Ingredient Review (CIR)
Mapped by: Existing checksum-valid CAS to unique PubChem CID match. Retrieved: 2026-08-31. Open source record
Scientific classifications and hazard annotations provide context and do not replace the market-specific regulatory decision shown above.
Additional source coverage and match status
| Source | Result | Checked |
|---|---|---|
| EMBL-EBI ChEBI | Needs review | 2026-08-31 |
| NIH PubChem PUG-View | Exact match | 2026-08-31 |
A recorded no-match is useful evidence that the source was checked; it is not a claim that the substance does not exist elsewhere.
Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.
Verified chemistry for CAS 27538-35-8
Ethyl urocanate
- IUPAC name
- ethyl (E)-3-(1H-imidazol-5-yl)prop-2-enoate
- Molecular formula
- C8H10N2O2
- Molecular weight
- 166.18 g/mol
- Exact mass
- 166.074227566 Da
- Monoisotopic mass
- 166.074227566 Da
- XLogP3
- 0.7
- Topological polar surface area
- 55.0 Ų
- Molecular complexity
- 180.0
- Formal charge
- 0
- Hydrogen-bond donors
- 1
- Hydrogen-bond acceptors
- 3
- Rotatable bonds
- 4
- Heavy atoms
- 12
- Covalent units
- 1
Names and synonyms reported to PubChem
16 more reported names
Advanced structure statistics
- Defined atom stereocentres
- 0
- Undefined atom stereocentres
- 0
- Defined bond stereocentres
- 1
- Undefined bond stereocentres
- 0
- 3D pharmacophore features
- 4
- 3D rings
- 1
- 3D hydrophobes
- 0
- 3D acceptor features
- 1
- 3D donor features
- 1
- 3D anionic centres
- 0
- 3D cationic centres
- 1
- 3D conformers
- 10
- Effective 3D rotors
- 4.0
Machine-readable structure identifiers
- SMILES
CCOC(=O)/C=C/C1=CN=CN1- InChI
InChI=1S/C8H10N2O2/c1-2-12-8(11)4-3-7-5-9-6-10-7/h3-6H,2H2,1H3,(H,9,10)/b4-3+- InChIKey
HPMLGOFBKNGJAM-ONEGZZNKSA-N
Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.
Official source and provenance
- Registered source
- Great Britain Cosmetics Regulation — consolidated Annexes II–VI and amendments
- Source reference
- GB Cosmetics Regulation, Annex II, entry 418
- Source record ID
II-418- Source version
- 2026-08-15
- Source language
- English
- Translation status
- Original is English
- Effective date
- 2026-08-15
- Source updated
- 2026-08-19
- Snapshot checked
- 2026-08-30 04:51 UTC
- Validation method
- legislation.gov.uk XML table parse; {'II': 1758, 'III': 326, 'IV': 154, 'V': 57, 'VI': 34}
- SHA-256
e3a386d950f54c6e7a7f9e784d1bd46e52de725137e89d5630709824475215d8
Registered dataset notes
- Dataset coverage
- Complete consolidated GB Annexes II–VI, with later amendments versioned separately
- Authority note
- Binding GB schedules and versioned amendments to retained Regulation 1223/2009; applies to England, Wales and Scotland, not Northern Ireland
- Source licence
- Open Government Licence v3.0 / Crown copyright
- Attribution
- Contains public sector information licensed under the Open Government Licence v3.0.
How this record fits the market dataset
Status distribution
Condition text is present on 517 of 2329 current records. An empty condition field is interpreted according to the record type above; it is never converted into an unrestricted-use claim.
Great Britain market context
Complete consolidated annex dataset
Coverage version: GB retained Regulation 1223/2009 schedules, effective 15 August 2026
Current consolidated Annexes II–VI for England, Scotland and Wales.
Verification checklist
- Confirm INCI/CAS/EC identity.
- Review every current GB Annex II–VI match.
- Check commencement dates and later statutory instruments.
- Verify SCPN, responsible-person, safety-report and labelling duties.
Official market sources
- Great Britain Cosmetics Regulation — consolidated Annexes II–VI and amendmentsBinding GB schedules and versioned amendments to retained Regulation 1223/2009; applies to England, Wales and Scotland, not Northern Ireland
Verification workflow and record completeness
Before using this result in a compliance decision
- Confirm that “3-Imidazol-4-ylacrylic acid (Urocanic acid) and its ethyl ester” and every CAS/EC identifier refer to the material in your supplier specification.
- Confirm INCI/CAS/EC identity.
- Review every current GB Annex II–VI match.
- Check commencement dates and later statutory instruments.
- Verify SCPN, responsible-person, safety-report and labelling duties.
- Document the source version and recheck the regulator before manufacture, notification or market placement.
Fields available in this record
- Official substance nameAvailable
- CASAvailable
- ECAvailable
- Separate condition textNot present in source row
- Effective dateAvailable
- Snapshot hash and methodAvailable
Questions this page answers
Stable citation
3-Imidazol-4-ylacrylic acid (Urocanic acid) and its ethyl ester. GB Cosmetics Regulation, Annex II, entry 418. Great Britain. Source version 2026-08-15. CosIng Checker regulatory record: https://cosingchecker.com/regulations/gb/records/4773/
Cite the regulator as the legal authority. This page is a structured evidence index and verification aid, not a substitute for the official text or professional legal assessment.
Interpretation and limits for Great Britain
This official record identifies the substance as prohibited for cosmetic use in the stated market scope.
Do not rely on a formulation containing this identity until the cited source, effective date and exact substance match have been verified.
How to interpret the legal role
The cited row forms part of a binding rule or legally incorporated list for this market.
Evidence on this page
- Recorded outcome: Prohibited
- Legal role: Binding rule
- Source version: 2026-08-15
- Effective date: 2026-08-15
What it does not prove
No annex match is not approval and does not cover Northern Ireland, which follows the applicable EU framework.
Further authoritative substance research
These sources can add identity, safety, exposure or hazard context. A link is not evidence that the database contains this exact substance, and none of these sources overrides the market decision above.
Cosmetic Ingredient Review safety assessments
Expert Panel conclusions, assessed ingredient groups, use conditions, dates and report documents
Independent expert review considered by FDA; not a government approval or binding market rule
Research this identity at the sourceFDA Global Substance Registration System
UNII identifiers, preferred names, substance types, codes and public substance relationships
Identity registry only; UNII availability does not imply FDA review or approval
Research this identity at the sourceILO/WHO International Chemical Safety Cards
Hazards, symptoms, first aid, storage, incompatibilities and physical properties for covered chemicals
International occupational chemical-safety reference; not cosmetic-use approval
Research this identity at the sourceJapan NITE-CHRIP
Chemical identity, Japanese and foreign legal lists, GHS hazards and exposure-related information
Chemical-management evidence; cosmetic status remains governed by the applicable MHLW standard and market rules
Research this identity at the sourceNIOSH Pocket Guide to Chemical Hazards
REL, PEL, IDLH, properties, exposure routes, symptoms, target organs, first aid and measurement methods for covered workplace chemicals
US occupational-health guidance and limits; not a cosmetic ingredient decision
Research this identity at the sourceOECD eChemPortal
Gateway to authority-owned physical-property, fate, ecotoxicity, toxicity, exposure and GHS records
Discovery gateway; each linked authority remains responsible for its data
Research this identity at the sourceUS EPA CompTox CTX APIs
API key required for importDTXSID identity, experimental and predicted properties, toxicity, bioactivity, exposure and environmental data
Scientific and computational evidence; predictions must remain labelled and do not determine cosmetic legality
Research this identity at the source