Also known as: 2-Butanone, MEK, AI3-07540, Caswell No. 569, EINECS 201-159-0 (+15 more)
INCI: MEK (ALSO KNOWN AS 2-BUTANONE / METHYL ETHYL KETONE)
MEK (Methyl Ethyl Ketone / 2-Butanone) (CAS 78-93-3) is a cosmetic cosmetic ingredient functioning as Solvent, denaturant. NOAEL 340 mg/kg bw/day (cross-referenced against ToxValDB ECHA IUCLID); EU Regulation 1223/2009 status: prohibited; GHS signal word DANGER. Industrial safety data is also available in the chemical safety database. Same-CAS public records also appear in industrial chemical safety and pharmaceutical data.
Auto-generated CPSR Part A draft with source citations
Cross-Vertical Regulatory Divergence
MEK (Methyl Ethyl Ketone / 2-Butanone) is prohibited in EU cosmetics but has active industrial GHS classifications (H225, H319, H336, H335, H303, H305, H315, H320).
US NotesAllowed - not specifically prohibited under 21 CFR 700; EPA has classified it as having low acute and low chronic toxicity. OSHA PEL is 200 ppm (590 mg/m³) for occupational exposure.
For full compliance data across multiple jurisdictions, use the
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Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for MEK (Methyl Ethyl Ketone / 2-Butanone).
Calculate MoS for your specific formulation with the
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Toxicological Studies
2 study endpoints found for MEK (Methyl Ethyl Ketone / 2-Butanone). 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
490 mg/kg bw/day
oral
rat
Short Term Toxicity
COSMOS_DB
NOAEL
981 mg/kg bw/day
oral
rat
Short Term Toxicity
COSMOS_DB
GHS Hazard Classification
Globally Harmonized System classification per ECHA C&L inventory and ILO/WHO International Chemical Safety Cards.
Signal Word
DANGER
Pictograms
FlamFlameExcl markWarnCancerHealth haz
Hazard Statements
Highly flammable liquid and vapour Causes serious eye irritation May cause respiratory irritation May cause drowsiness or dizziness Suspected of damaging fertility or the unborn child May be harmful if swallowed and enters airways
Short-term Exposure Effects
The substance is irritating to the eyes and respiratory tract. The substance may cause effects on the central nervous system. Exposure could cause unconsciousness. If swallowed the substance easily enters the airways and could result in aspiration pneumonitis.
Long-term Exposure Effects
The substance defats the skin, which may cause dryness or cracking. Animal tests show that this substance possibly causes toxicity to human reproduction or development.
Routes of Exposure
The substance can be absorbed into the body by inhalation, by ingestion and through the skin.
Pre-Calculated Safety Assessment
Pre-calculated NOAEL → SED → MoS audit trail for MEK (Methyl Ethyl Ketone / 2-Butanone) across SCCS product categories, with measured dermal absorption where available.
EPA ToxValDB — Toxicity Values
10 toxicity values from EPA ToxValDB (aggregated from CCTE, HPV, ToxRefDB, IRIS, and other regulatory dossiers).
Endpoint
Value
Species
Route
Duration
Source
NOAEL
=589.835 mg/m3
Human
inhalation
acute
TX TCEQ
NOAEL
=14866.8 mg/m3
Rat
inhalation
subchronic
TX TCEQ
MRL
=2.94918 mg/m3
Human
inhalation
-
ATSDR MRLs
RfD
=0.6 mg/kg-day
Human
oral
-
OW Drinking Water Standards
LEL
=53085.2 mg/m3
Human
inhalation
-
DOE Protective Action Criteria
LOAEL
=796.278 mg/m3
Human
inhalation
acute
Cal OEHHA REL derivations
LD50
>10 mL/kg bw
Rabbit
dermal
acute
ECHA IUCLID
LD50
=4.29 mL/kg bw
Rat
oral
-
ECHA IUCLID
LOAEL
=20000 mg/L
Rat
oral
-
ECHA IUCLID
LOAEL
=20000 mg/L
Rat
oral
-
ECHA IUCLID
EU CLP Annex VI Harmonized Classification
Legally binding harmonized classification per Regulation (EC) No 1272/2008 (CLP) Annex VI.
Signal Word
Danger
Pictograms
FlammableHarmful / Irritant
Hazard Class and Category
Flam. Liq. 2; STOT SE 3; Eye Irrit. 2
Hazard Statements
H225Highly flammable liquid and vapour
H336May cause drowsiness or dizziness
H319Causes serious eye irritation
Inserted via ATP: CLP00
HRIPT Human Patch Test Studies
1 human repeat insult patch test aggregated from dermatological literature.
Test Type
N
Sensitized
Dose µg/cm²
NESIL µg/cm²
Potency
HMT
-
0
13500
-
-
Endocrine Disruptor Evidence (Expanded)
Cross-referenced EDC classifications, mechanism data, and dose-response evidence from EDLists, SIN List, and cosmetic-specific detail sources.
SuspectedEvidence: Limited(2018)
Health effects:Yes
Affected pathways:Thyroid
Regulatory framework:REACH
Source list: II
ECHA REACH Registration
European Chemicals Agency REACH dossier and Substances of Very High Concern listing.
Registration Type
Full
Tonnage Band
100,000 - 1,000,000 tonnes
Substance Type
SUBSTANCE
SVHC Candidate
No
Hazard classification:Restricted (Annex XVII)
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:72.1
Log Kow:0.37
Log Kp:-2.3467874862246565
Log Jmax:-4.86
Source: Roberts_Cheruvu_Mendeley_2022
PubChem Annotations
Safety and regulatory annotations from PubChem (NCBI) aggregated sources.
Safety (5)
Carcinogen Classification
No indication of carcinogenicity to humans (not listed by IARC).
Source: Toxin and Toxin Target Database (T3DB)
Evidence for Carcinogenicity
Cancer Classification: Group D Not Classifiable as to Human Carcinogenicity | CLASSIFICATION: D; not classifiable as to human carcinogenicity. BASIS FOR CLASSIFICATION: Based on no human carcinogenicity data and inadequate animal data. HUMAN CARCINOGENICITY DATA: None. ANIMAL CARCINOGENICITY DATA: Inadequate.
Source: Hazardous Substances Data Bank (HSDB)
Endocrine Disruptors
Potential endocrine disrupting compound
Source: NORMAN Suspect List Exchange
ICSC Safety Card
0179
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Skin Eye Respiratory Irritation
High atm concn ... are irritating to the eyes, nose, and throat ... . | Irritates the eyes and the respiratory tract.
Source: Hazardous Substances Data Bank (HSDB)
Regulatory (2)
JECFA Number
278
Source: Joint FAO/WHO Expert Committee on Food Additives (JECFA)
JECFA Evaluation
ETHYL METHYL KETONE | 1998 | No safety concern at current levels of intake when used as a flavouring agent | TRS 891-JECFA 51/59 | FAS 42-JECFA 51/235
Source: Joint FAO/WHO Expert Committee on Food Additives (JECFA)
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Adhesion/cohesion promoterCatalystDegradant/impurityFlavouring and nutrientFragranceNo specific technical functionSolvent
Regulatory List Membership (3)
IFRA Fragrance Transparency ListFDA Substances Added to Food (EAFUS)Consumer Product Chemical
Expert Verdict
Expert safety assessment and concern-level summary for MEK (Methyl Ethyl Ketone / 2-Butanone).
Is MEK (Methyl Ethyl Ketone / 2-Butanone) safe in cosmetics?
MEK (Methyl Ethyl Ketone / 2-Butanone) has a safety rating of "MODERATE" in our database. EU status: prohibited. US status: permitted. 2 toxicological study endpoint(s) are available in our database.
Is MEK (Methyl Ethyl Ketone / 2-Butanone) allowed in the EU?
MEK (Methyl Ethyl Ketone / 2-Butanone) EU regulatory status: prohibited. This is based on EU Regulation 1223/2009 and its amendments.
What does MEK (Methyl Ethyl Ketone / 2-Butanone) do in cosmetics?
MEK (Methyl Ethyl Ketone / 2-Butanone) functions as: Solvent, denaturant. It is classified as a cosmetic ingredient in our database. CAS number: 78-93-3.
What is the NOAEL for MEK (Methyl Ethyl Ketone / 2-Butanone)?
The NOAEL (No Observed Adverse Effect Level) for MEK (Methyl Ethyl Ketone / 2-Butanone) is 490 mg/kg bw/day based on a Short Term Toxicity study via oral route in rat. A total of 2 study endpoints are available. Source: COSMOS_DB.
Is MEK (Methyl Ethyl Ketone / 2-Butanone) classified as hazardous under GHS?
MEK (Methyl Ethyl Ketone / 2-Butanone) carries a GHS signal word of "DANGER". Hazard statements: Highly flammable liquid and vapour Causes serious eye irritation May cause respiratory irritation May cause drowsiness or dizziness Suspected of damaging fertility or the unborn child May be harmful if swallowed and enters airways. This classification is based on the ILO/WHO International Chemical Safety Card and ECHA C&L inventory data. Note: GHS classification applies to the pure substance — at cosmetic use concentrations, hazard thresholds may not be met.
Is MEK (Methyl Ethyl Ketone / 2-Butanone) used outside cosmetics?
MEK (Methyl Ethyl Ketone / 2-Butanone) also appears in industrial chemical safety and pharmaceutical data. The cross-vertical cards on this page render same-CAS public rows from the matched databases.
Does MEK (Methyl Ethyl Ketone / 2-Butanone) have different safety status in cosmetics vs industrial chemicals?
MEK (Methyl Ethyl Ketone / 2-Butanone) is prohibited in EU cosmetics but has active industrial GHS classifications (H225, H319, H336, H335, H303, H305, H315, H320).
Is MEK (Methyl Ethyl Ketone / 2-Butanone) in Your Products?
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