Methyl ethyl ketone (MEK), also known as butanone, is an organic compound with the molecular formula CH₃C(O)CH₂CH₃. This colourless liquid has a sharp, sweet odour similar to butterscotch and acetone. MEK is produced industrially in large quantities, although it also occurs naturally in trace amounts. It is soluble in water and commonly used as an industrial solvent.
What is Methyl Ethyl Ketone used for?
MEK is widely used in:
Surface coatings
Adhesives
Printing inks
Chemical intermediates
Magnetic tapes
Lube oil de-waxing agents
It is also used to extract fats, oils, waxes, and resins. MEK is known for being a highly efficient and versatile solvent, especially useful in high-solids coatings that help reduce emissions during coating operations.
Interestingly, MEK is also a natural component found in foods such as
Apple juice
Beans
Chicken
Honey
A variety of cheeses
Methyl Ethyl Ketone (MEK) is a natural component found in apple juice.
Sources of Emission and Routes of Exposure
Sources of Emission
Industry Sources
Major sources include industries that manufacture or use MEK, such as
Chemical manufacturing
Rubber and pharmaceutical industries
Semiconductor production
Heavy equipment manufacturing
Paints, inks, varnishes, and lacquers
Millwork, veneer, and plywood manufacturing
These emissions primarily go into the air unless there is a spill.
Diffuse Sources
These include:
Commercial and household painting
Varnish and lacquer removal
Tobacco smoke
Consumer products containing MEK
Natural Sources
MEK is naturally present in:
Volcanoes
Forest and bush fires
Biodegradation byproducts
Certain foods
Transport Sources
Found in motor vehicle exhaust.
Consumer Products
MEK is present in many everyday products, including
Aerosol paints
Household cleaners
Nail polish and removers
Insecticides
Shoe polish
Paints, varnishes, thinners
Lubricants
Markers
Furniture finishes and waterproofing compounds
Routes of Exposure
You may be exposed to MEK through:
Breathing contaminated air from paints, glues, or cleaning agents
Breathing near hazardous waste sites or from cigarette smoke
Sniffing glues
Drinking contaminated well water
Skin contact during use or production
Health Effects
Acute Effects
Short-term exposure to high MEK levels can cause:
Irritation of eyes, nose, and throat
Headaches and nausea
Central nervous system depression
Dermatitis (from skin exposure)
In animals:
Rabbits: high toxicity from skin exposure
Rats and mice: moderate toxicity from ingestion
Rats: low toxicity from inhalation
Chronic Effects
Long-term exposure data is limited. However:
One human study found nerve damage in individuals sniffing glue thinners with MEK.
Animal studies report minor neurological, liver, kidney, and respiratory effects.
EPA Reference Values:
RfC: 1 mg/m³ (based on decreased foetal birth weight in mice)
RfD: 0.6 mg/kg/day (based on decreased foetal birth weight in rats)
Reproductive/Developmental Effects
No information available for humans
Animal studies reported:
No histological alterations in the testes and epididymides in mice exposed by inhalation
No changes in reproductive index in pregnant mice given the chemical by gavage (feeding tube)
Cancer Risk
No human carcinogenicity data
No animal studies via oral/inhalation routes
No skin tumours in dermal studies
EPA Classification: Group D – Not classifiable for human carcinogenicity due to lack of data.
Safety
First Aid Measures
Eye Contact
Remove contact lenses
Rinse eyes with water for 15 minutes
Seek medical attention
Skin Contact
Flush skin with water and apply emollient
Remove contaminated clothing and clean thoroughly
Get medical attention if needed
Serious Skin Contact
Wash with disinfectant soap
Apply antibacterial cream
Seek medical attention
Inhalation
Move to fresh air
Provide oxygen or perform artificial respiration if needed
Seek medical attention
Serious Inhalation
Evacuate to a safe area
Loosen tight clothing
Provide oxygen or perform mouth-to-mouth resuscitation
Seek immediate medical help
Ingestion
Do NOT induce vomiting
Loosen tight clothing
Do not give anything by mouth to an unconscious person
Get medical attention
Fire & Explosion Information
Flammable
Auto-ignition temperature: 404°C
Highly flammable in presence of open flames and sparks
Explosive with oxidising materials
Vapours may cause flash fires
Firefighting Measures:
Small fires: use dry chemical powder
Large fires: use alcohol foam, water spray, or fog
Avoid contact with potassium t-butoxide and hydrogen peroxide/nitric acid mixture (forms explosive compounds)
May produce explosive peroxides when stored with 2-propanol
Exposure Control & Personal Protection
Engineering Controls
Use exhaust ventilation to maintain vapour levels below thresholds
Ensure eyewash stations and safety showers are nearby
Personal Protective Equipment (PPE)
Standard Handling:
Splash goggles
Lab coat
Vapour respirator (approved type)
Gloves
Large Spill Response:
Splash goggles
Full suit
Vapour respirator
Boots
Gloves
Self-contained breathing apparatus recommended
Always consult a safety specialist before handling
Central nervous system effects and peripheral neuropathy
HE16
Irritation of the eyes, nose, and throat
Australia
Safe Work Australia: For methyl ethyl ketone, it is allowable for workers to be exposed to concentrations of 150 parts per million over an eight hour workshift, with concentrations not greater than 300 parts per million.
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