Also known as: Mesityl oxide, Acetone, isopropylidene-, BRN 1361550, Caswell No. 547, EINECS 205-502-5 (+15 more)
CAS 141-79-7
4-Methylpent-3-en-2-one (CAS 141-79-7) is a chemical substance with GHS signal word Warning; key hazard signal: H226; H332; H312; H302. Key regulatory status: REACH registered, 4 regulatory/inventory lists, cosmetic ingredient cross-reference; source data from ECHA CLP, EPA ToxValDB, EPA CPDat, AICIS, ECHA REACH, ILO ICSC, OSHA.
View cosmetic safety profile for 4-Methylpent-3-En-2-One (Mesityl Oxide) →
CAS, identifiers, formula, and alternate names for the matched substance record.
EU harmonized hazard classification, hazard statements, pictograms, and signal word.
| Hazard Class | H-Statements | Pictograms | Signal |
|---|---|---|---|
| Flam. Liq. 3; Acute Tox. 4 *; Acute Tox. 4 *; Acute Tox. 4 * | H226; H332; H312; H302 | GHS02; GHS07 | Warning |
International Chemical Safety Card hazard and exposure summary.
| Field | Value |
|---|---|
| GHS Signal Word | DANGER |
| GHS Hazard Statements | Flammable liquid and vapour Harmful if swallowed Toxic if inhaled Causes skin and eye irritation May cause respiratory irritation May cause damage to organs through prolonged or repeated exposure May be harmful if swallowed and enters airways Harmful to aquatic life |
| Short-term Effects | The substance is irritating to the eyes, skin and respiratory tract. Exposure far above the OEL could cause unconsciousness. If swallowed the substance may cause vomiting and could result in aspiration pneumonitis. |
| Long-term Effects | The substance defats the skin, which may cause dryness or cracking. The substance may have effects on the liver, kidneys and lungs. |
| Routes of Exposure | The substance can be absorbed into the body by inhalation of its vapour and by ingestion. |
Occupational exposure limits from OSHA, NIOSH, and ACGIH rows.
| Agency | Metric | Value | ppm | mg/m3 | Skin |
|---|---|---|---|---|---|
| OSHA | TWA | 25 ppm (100 mg/m³) | 25 | 100 | N |
| NIOSH | TWA | 10 ppm (40 mg/m³) | 10 | 40 | N |
| ACGIH | TWA | 15 ppm [1992] | 15 | - | N |
| ACGIH | STEL | 25 ppm [1992] | 25 | - | N |
| CAL/OSHA | TWA | 15 ppm (60 mg/m³) | 15 | 60 | N |
| CAL/OSHA | STEL | 25 ppm (100 mg/m³) | 25 | 100 | N |
| NIOSH | IDLH | 1400 ppm | 1400 | - | - |
Industrial and product-use categories associated with this substance.
Inventory, screening, and regulatory list matches from public chemical databases.
| List | Keyword | Source |
|---|---|---|
| IFRA Transparency | IFRA | IFRA |
| food_additive; Substances Added to Food (formerly EAFUS) (2/2019) | FDA | United States Food and Drug Administration (FDA) |
| Europe | European Commission | Fl@vis |
| inert_ingredient; non_food_use; Pesticides | EPA | CPCat |
Toxicology endpoints rendered from public NOAEL study rows.
| Value | Unit | Endpoint | Route | Species | Source |
|---|---|---|---|---|---|
| 17.1754944710979 | uM | AC50 | - | - | NTP_ICE_endocrine |
| 6.5099893305711 | uM | ACC | - | - | NTP_ICE_endocrine |
| =20.4 | mg/m3 | DNEL local | inhalation | Human | ToxValDB_GESTIS_DNEL |
| 77LAC84669 | UNII | FDA UNII substance identifier | - | - | openFDA substances |
| 77LAC84669 | UNII | FDA UNII substance identifier | - | - | openFDA substances |
| 77LAC84669 | UNII | FDA UNII substance identifier | - | - | openFDA substances |
| 77LAC84669 | UNII | FDA UNII substance identifier | - | - | openFDA substances |
| 9 | mg/L | LC50 | Inhalation | - | NTP_ICE_acute_inhalation |
| =52183.7 | mg/m3 | LEL | inhalation | Rabbit | ToxValDB_ECHA_IUCLID |
| =56197.8 | mg/m3 | LEL | inhalation | Human | ToxValDB_DOE_Protective_Action_Criteria |
| =124.438 | mg/m3 | LOAEC | inhalation | Rat | ToxValDB_ECHA_IUCLID |
| - | unitless | Model Score | - | - | NTP_ICE_endocrine |
| 0.14 | unitless | Model Score | - | - | NTP_ICE_endocrine |
Showing 13 of 13 studies
Registration status from the ECHA REACH registered substances database.
| Status | Name | EC Number | Link |
|---|---|---|---|
| Registered | 4-methylpent-3-en-2-one | 205-502-5 | ECHA overview → |
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 food additive, ADI, and GRAS records where available.
ADI: No safety concern at current levels of intake when used as a flavouring agent mg/kg bw
View full food safety profile →Same-CAS cannabis compliance and lab records where available.
1 cannabis record found in efsa substances.
View full cannabis profile →4-Methylpent-3-en-2-one (CAS 141-79-7) is classified under EU CLP Annex VI as Flam. Liq. 3; Acute Tox. 4 *; Acute Tox. 4 *; Acute Tox. 4 * with signal word Warning. Hazard statements: H226; H332; H312; H302. Source: EU CLP Annex VI (ECHA).
4-Methylpent-3-en-2-one has 13 NOAEL studies in the database. The lowest reported value is 6.5099893305711 uM. Source: NTP_ICE_endocrine.
4-Methylpent-3-en-2-one appears on 4 regulatory/inventory lists including IFRA Transparency, food_additive; Substances Added to Food (formerly EAFUS) (2/2019), Europe, and 1 more. Source: EPA CPDat.
Occupational exposure limits for 4-Methylpent-3-en-2-one are set by OSHA, NIOSH, ACGIH. 7 limit values from official agencies are documented in the database. Source: OSHA, NIOSH, ACGIH.
Yes, 4-Methylpent-3-en-2-one is also indexed as a cosmetic ingredient under the name 4-Methylpent-3-En-2-One (Mesityl Oxide). 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, ECHA REACH, ILO/WHO ICSC, OSHA/NIOSH/ACGIH, CosIng / Ingredients DB, ChEMBL / DailyMed, EFSA / FDA GRAS, cannabis regulatory/lab databases. All data traces to primary regulatory sources and is updated from official government databases.
4-Methylpent-3-en-2-one also appears in cosmetics, pharmaceutical, food safety, cannabis databases.