Is Alpha-Isomethyl Ionone safe in cosmetics?
Alpha-Isomethyl Ionone has a safety rating of "GOOD" in our database. EU status: permitted. US status: permitted. 2 toxicological study endpoint(s) are available in our database.
Alpha-Isomethyl Ionone
Also known as: 3-Buten-2-one, 3-methyl-4-(2,6,6-trimethyl-2-cyclohexen-1-yl)-, Isomethyl-α-ionone, Cetone Alpha, 3-Methyl-4-(2,6,6-trimethyl-2-cyclohexen-1-yl)-3-buten-2-one, α-Cetone (+10 more)
INCI: ALPHA-ISOMETHYL IONONE
Alpha-Isomethyl Ionone (CAS 127-51-5) is a cosmetic fragrance functioning as Fragrance ingredient. NOAEL 3.55 mg/kg bw/day (cross-referenced against ToxValDB ECHA IUCLID); EU Regulation 1223/2009 status: permitted. Industrial safety data is also available in the chemical safety database. Same-CAS public records also appear in industrial chemical safety, pharmaceutical, and food safety data.
View industrial chemical safety profile for CAS 127-51-5 →
Auto-generated CPSR Part A draft with source citations
Function
Fragrance ingredient
Safety Rating
GOOD
Regulatory Status
EU EU Status
permitted
US US Status
permitted
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for Alpha-Isomethyl Ionone.
Calculate MoS for your specific formulation with the MoS Calculator.
Toxicological Studies
2 study endpoints found for Alpha-Isomethyl Ionone. 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 | 4.1 mg/kg bw/day | oral | rat | Subchronic | COSMOS DB |
| NOAEL | =500 mg/kg bw/day | oral | Rat | reproduction developmental | ECHA |
Pre-Calculated Safety Assessment
Pre-calculated NOAEL → SED → MoS audit trail for Alpha-Isomethyl Ionone across SCCS product categories, with measured dermal absorption where available.
Sensitization Profile
Contact sensitization data for Alpha-Isomethyl Ionone based on clinical patch test studies and IFRA standards.
Sensitization Rate
low
Allergen Class
fragrance
EU Allergen Listed
yes
Patch Test Positive Rate
0.5%
Cross-reactivity Group
fragrance-mix-II
Reaction Type
contact-dermatitis
IFRA Restricted
Source: ESSCA/IVDK
Dermal Penetration Profile
Skin absorption and penetration characteristics of Alpha-Isomethyl Ionone, relevant to systemic exposure and MoS calculations.
Absorption %
15-25%
Penetration Level
epidermis
Penetration Depth
epidermis
Molecular Weight
206.3 Da
Log P
3.9
Systemic Absorption
yes
Topical Bioavailability
10-20%
Safety Margin Factor
high
Vehicle Dependent
Yes — absorption varies by formulation
Source: SCCS Opinion
Sensitization AOP Dashboard
Adverse Outcome Pathway data across 5 assays (DPRA, KeratinoSens, hCLAT, LLNA, NESIL) aggregated from public sources.
DPRA Cys %
4.94%
DPRA Lys %
0.2%
KeratinoSens IC50
60.025 µM
hCLAT CV75
62.3 µg/mL
LLNA EC3
21.8%
NESIL
1860 µg/cm²
LLNA: Weak (1B)
GHS: 1B
Human: positive
Source: LLNA: Kern et al. (2010); DPRA: Hoffmann et al., 2018 | Urbisch et al. 2015 [DOI:10.1016/j.yrtph.2014.12.008]; KS: Natsch et al. 2015 [DOI:10.1093/toxsci/kfu229] | Urbisch et al. 2015 [DOI:10.1016/j.yrtph.2014.12.008]; hCLAT: Urbisch et al. 2015 [DOI:10.1016/j.yrtph.2014.12.008]; HPPT: [285] RIFM (1968): RIFM report number 15453, November 18, unpublished.
HRIPT Human Patch Test Studies
5 human repeat insult patch tests aggregated from dermatological literature.
| Test Type | N | Sensitized | Dose µg/cm² | NESIL µg/cm² | Potency |
|---|---|---|---|---|---|
| HRIPT | 106 | 0 | 70860 | 70860 | non-sensitizer |
| HRIPT | - | 0 | 1860 | - | - |
| HRIPT | - | 0 | 6200.01 | - | - |
| HRIPT | - | 0 | 9687.52 | - | - |
| HRIPT | - | 0 | 70866.14 | - | - |
Endocrine Disruptor Evidence (Expanded)
Cross-referenced EDC classifications, mechanism data, and dose-response evidence from EDLists, SIN List, and cosmetic-specific detail sources.
Cosmetic-Specific Mechanism
Category: fragrance
Receptor targets: ERα (limited)
LOEC: 100 µM
EU status: allowed (allergen labeling)
weak modulator
ECHA REACH Registration
European Chemicals Agency REACH dossier and Substances of Very High Concern listing.
Registration Type
Full
Tonnage Band
100 - 1,000 tonnes
Substance Type
SUBSTANCE
SVHC Candidate
No
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 (III - Restricted)
BRIN Brazil/India Cosmetics
Brazil: Restricted (Fragrance Allergen) · max >0.001% leave-on / >0.01% rinse-off requires labeling
India: Restricted
Additional Ingredient Properties
6 property records from structured ingredient metadata.
allergen_detail
{"eu_allergen_listed": "yes", "allergen_class": "fragrance", "cross_reactivity_group": "fragrance-mix-II", "patch_test_frequency_pct": "0.5", "sensitization_rate": "low", "common_reaction_type": "contact-dermatitis", "ifra_restricted": "yes", "source": "ESSCA/IVDK"}
dermal_absorption
{"molecular_weight_da": "206.3", "log_p_value": "3.9", "skin_penetration_level": "epidermis", "penetration_depth": "epidermis", "absorption_pct": "15-25", "systemic_absorption": "yes", "penetration_enhancer": "yes", "occlusion_effect": "no", "vehicle_dependent": "yes", "skin_barrier_effect": "neutral", "bioavailability_topical_pct": "10-20", "safety_margin_factor": "high", "source": "SCCS/1459/11,…
fragrance
{"cas_number": "127-51-5", "ingredient_class": "aroma_chemical", "chemical_class": "ionone", "odor_family": "floral", "odor_description": "Violet-like, orris, powdery, woody", "odor_strength": "strong", "odor_tenacity_hours": "72.0", "top_note": "no", "heart_note": "yes", "base_note": "yes", "blending_factor_1_10": "8.0", "threshold_of_detection_ppb": "25.0", "molecular_weight_Da": "206.32", "boil…
pregnancy_detail
{"pregnancy_safe": "insufficient-data", "breastfeeding_safe": "insufficient-data", "risk_category": "not-rated", "reason": "Fragrance allergen; limited pregnancy data", "alternative_ingredient": "Fragrance-free", "source": "dermatology literature"}
regulatory
{"eu_status": "restricted", "us_status": "allowed", "eu_max_concentration": "0.001", "restricted_in": "rinse-off: >0.01%, leave-on: >0.001%", "regulation_reference": "Annex III/205"}
skin_suitability
{"oily_skin": "caution", "dry_skin": "caution", "sensitive_skin": "caution", "combination_skin": "caution", "normal_skin": "caution", "acne_prone": "caution", "rosacea": "caution", "eczema": "caution", "hyperpigmentation": "caution", "aging_mature": "caution", "dehydrated": "caution", "skin_benefit_primary": "fragrance", "skin_benefit_secondary": "violet-scent", "mechanism_of_action": "Synthetic v…
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Deodorizer
Flavouring and nutrient
Fragrance
Softener and conditioner
Regulatory List Membership (4)
EU Restricted for Children (Cosmetics)
IFRA Fragrance Transparency List
FDA Substances Added to Food (EAFUS)
EU CosIng Cosmetics Ingredient Database
Expert Verdict
Expert safety assessment and concern-level summary for Alpha-Isomethyl Ionone.
Regulatory Flags
eu_children_restricted
ifra_fragrance
fda_food_additive
eu_cosing_listed
NOAEL Studies Summary
View details ->Public NOAEL study rows linked to Alpha-Isomethyl Ionone by CAS number or substance name.
Studies
2
Lowest NOAEL
4.1 mg/kg bw/day
Highest NOAEL
500 mg/kg bw/day
COSMOS DB
ECHA
Known Synonyms
3-Buten-2-one, 3-methyl-4-(2,6,6-trimethyl-2-cyclohexen-1-yl)-
Isomethyl-α-ionone
Cetone Alpha
3-Methyl-4-(2,6,6-trimethyl-2-cyclohexen-1-yl)-3-buten-2-one
α-Cetone
α-Ionone, isomethyl-
EINECS 204-846-3
FEMA No. 2714
alpha-Ionone, isomethyl-
Isomethyl-alpha-ionone
Methyl-alpha-isoionone
NSC 66432
4-(2,6,6-Trimethyl-2-cyclohexen-1-yl)-3-methyl-3-buten-2-one
alpha-Cetone
UNII-9XP4LC555B
Chemical Function
Fragrance
Regulatory Lists
Europe; Personal care; restricted
inert_ingredient; non_food_use; Pesticides
Europe
Cleaning products and household care - air freshener; detected; Europe; Vehicle - car interior - auto air freshener
children; Europe; Personal care - specialized bath products - bath salts
children; Europe; Personal care - general moisturizing - hand/body lotion
IFRA Transparency
Europe; Personal care - body hygiene - hand soap
children; Europe; Personal care
children; Europe; Personal care
Europe; Personal care - deodorant
Europe
Cleaning products and household care - laundry and fabric treatment - laundry detergent; Europe
children; detected; Europe; Personal care - body hygiene - body wash; Personal care - fragrance; Personal care - general moisturizing - hand/body lotion; Personal care - specialized bath products - bubble bath
children; detected; Europe; Personal care
detected; Europe; Personal care - deodorant
detected; Europe; Personal care - deodorant
food_additive; Substances Added to Food (formerly EAFUS) (2/2019)
Australian Status
AICIS status: listed
Cross-Vertical Safety Context
Same-CAS public records found in pharmaceutical and food safety data.
SOURCE
ChEMBL / DrugCentral / FAERS
DB_PHARMA CAS match
Pharmaceutical Data
Same-CAS rows from the pharmaceutical spoke database.
ChEMBL ID
CHEMBL3183353
SOURCE
EFSA / FDA GRAS
food_additives
Food Safety Data
Same-CAS food additive or FDA GRAS records from the core public database.
Food Name
ALPHA-ISOMETHYLIONONE
Food Category
flavoring
Frequently Asked Questions
Is Alpha-Isomethyl Ionone allowed in the EU?
Alpha-Isomethyl Ionone EU regulatory status: permitted. This is based on EU Regulation 1223/2009 and its amendments.
What does Alpha-Isomethyl Ionone do in cosmetics?
Alpha-Isomethyl Ionone functions as: Fragrance ingredient. It is classified as a Fragrance in our database. CAS number: 127-51-5.
What is the NOAEL for Alpha-Isomethyl Ionone?
The NOAEL (No Observed Adverse Effect Level) for Alpha-Isomethyl Ionone is 4.1 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.
Is Alpha-Isomethyl Ionone used outside cosmetics?
Alpha-Isomethyl Ionone also appears in industrial chemical safety, pharmaceutical, and food safety data. The cross-vertical cards on this page render same-CAS public rows from the matched databases.
Compliance Tools
Check Alpha-Isomethyl Ionone compliance across multiple jurisdictions:
Ingredient Decoder
Paste a full ingredient list for instant analysis
82 Allergen Checker
Check for EU declarable fragrance allergens
Substance Compliance
Check compliance across multiple jurisdictions
MoS Calculator
Calculate Margin of Safety using SCCS methodology
Heavy Metal Limits
Compare limits across jurisdictions
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