4-Methyl-2-pentanone

Methyl isobutyl ketone has been identified in the expired air from a non-smoking heterogenous study population(1). Methyl isobutyl ketone was found in expelled breath of humans at 1-10 ppb(2). Methyl isobutyl ketone had air concentration/urinary concentration correlation coefficients of 0.81 and 0.91 in 36 and 28 human subjects, respectively(3).

USDA APHIS Chemical Effects: collection=usda_chemeffect&query_type=synonym&query='^108-10-1$'

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), methyl isobutyl ketone, which has a vapor pressure of 19.9 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase methyl isobutyl ketone is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 30(SRC), calculated from its rate constant of 1.3X10-11 cu cm/molecule-sec at 25 °C(3). Methyl isobutyl ketone absorbs UV at wavelengths >290 nm(3) and, therefore, may be susceptible to direct photolysis by sunlight(SRC).

The Koc of methyl isobutyl ketone is estimated as 70(SRC), using a log Kow of 1.31(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that methyl isobutyl ketone is expected to have high mobility in soil.

ANAEROBIC: The theoretical methane recovery of methyl isobutyl ketone in an anaerobic aquifer was 46% over a 3 week incubation period(1).

An estimated BCF of 3 was calculated in fish for methyl isobutyl ketone(SRC), using a log Kow of 1.31(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Henry's Law constant for methyl isobutyl ketone is estimated as 1.4X10-4 atm-cu m/mole(SRC) derived from its vapor pressure, 19.9 mm Hg(1), and water solubility, 19,000 mg/L (2). This Henry's Law constant indicates that methyl isobutyl ketone is expected to volatilize from water surfaces(3). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(3) is estimated as 9 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(3) is estimated as 6 days(SRC). Methyl isobutyl ketone's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). The potential for volatilization of methyl isobutyl ketone from...

The rate constant for the vapor-phase reaction of methyl isobutyl ketone with photochemically-produced hydroxyl radicals has been measured as 1.30X10-11 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 30 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(SRC). The photochemical degradation products of methyl isobutyl ketone with hydroxyl radicals are acetone and 2-methylpropanal(2). Methyl isobutyl ketone is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(3). Methyl isobutyl ketone in cyclohexane exhibits strong absorption of UV light >290 nm(4), and, therefore, may be susceptible to direct photolysis by sunlight(SRC).

SURFACE WATER: Methyl isobutyl ketone was identified, not quantified, in Cuyahoga River(1) and in 1 out of 204 samples of surface water collected near heavily industrialized areas across the US(2). Methyl isobutyl ketone was identified, not quantified, in 1 out of 17 samples of Delaware River water(3). Methyl isobutyl ketone was detected at mean concentrations of 57.1 ug/L (range, 2.8-332 ug/L) and 1.2 ug/L (range, 0.01-5.60 ug/L) in the Adige River, Italy(4). Methyl isobutyl ketone was detected at a concentration of less than 10 ug/L in the Potomac River(5). Dutch surface water samples taken from 1992 to 1997 had average concentrations of <0.1, 0.1, 0.3, and 0.3 ug/L for the Rhine, Meuse, Northern Delta area, and Westerscheldt, respectively(6).

Methyl isobutyl ketone has been reported found in orange and lemon juice, grape; vinegar, baked potato, papaya, ginger, wheat bread, cheeses, cooked egg, roast chicken, cooked beef, lamb fat, pork liver, hop oil, beer, cognac, coffee, tea, plumcot, plum brandy, mushroom, trassi, sesame seed, buck wheat, wort, elder, Bourbon vanilla, clary and red sage

Methyl isobutyl ketone has been reported found in milk

/AQUATIC SPECIES/ Aquatic invertebrates are less sensitive than fish to the toxicity of MIBK. ...The toxicity of MIBK was also measured in the green alga Scenedesmus quadricauda, in which the 8-day threshold for toxicity was 725 mg/L, and in the relatively more sensitive cyanobacterium (blue-green alga) Microcystis aeruginosa, in which the toxicity threshold was 136 mg/L.

Methyl isobutyl ketone was found in highway tunnels in Tuscarora; light duty trucks emitted 0.014 mg/km traveled or 0.211 mg/L fuel used, heavy duty trucks emitted 0.079 mg/km traveled or 0.248 mg/L fuel used(1). Emission factors for light-duty vehicles were 0.88, 0.45 and 0.62 mg/kg in 1999, 2001 and 2006, respectively(2). The emission factor for moderate/heavy duty diesel trucks was 2.3 mg/kg in 2006. Measurements were taken in the Caldecott Tunnel, San Francisco Bay area on CA Hwy 24(2).

Methyl isobutyl ketone has been reported found in camphor, elderberry, ginger(1) and Chinese quince(2).

SOURCE DOMINATED: Methyl isobutyl ketone was found at 1 ppm at two biogas production facilities Aug 2000 and Feb 2003 in Linkoping, Sweden(1).

Methyl isobutyl ketone was detected at concentrations of 43.6 ng/g and 93.6 ng/g in salt-fermented anchovies and shrimp, respectively(1). Methyl isobutyl ketone has been reported found in crab, clam(2).

Methyl isobutyl ketone's production and use as a solvent for gums, resins, nitrocellulose, paints, varnishes, and lacquers, denaturant agent for rubbing alcohol, in the manufacture of methyl amyl alcohol and in dry-cleaning preparations(1) may result in its release to the environment through various waste streams(SRC). Its use as an extracting agent for the production of antibiotics and for the removal of paraffins from mineral oil for the production of lubricating oils(1) may also result in its release to the environment through various waste streams(SRC). Methyl isobutyl ketone has been approved for use as a component of synthetic flavoring substances and as a component of adhesives and resins that are used in packaging, transporting, or holding food(3).

SOIL: Methyl isobutyl ketone was detected in the soil of a Michigan waste disposal facility at a concentration of 4 ug/kg(1). Methyl isobutyl ketone was found in 0.6% of 705 soil samples taken from 30 industrial sites in Taiwan(2).

The most likely exposure routes for methyl isobutyl ketone in the workplace are by inhalation of the vapors and by skin and eye contact(1). Methyl isobutyl ketone, hexamethyldisiloxane and ethyl 2-cyanoacrylate were present in workplace air at a range of 0.001-0.73 ppm from 20 nail sculpturing salons in southeast Norway(2). Methyl isobutyl ketone was present at average concentrations of 1.99 and 1.63 ppm for aircraft paint stripping and spraying workers, respectively, during 1-2 hour personal sampling(3).

Methyl isobutyl ketone was given off aluminum evaporator sections of automobile air conditioning systems after 8 days at concentrations of 27 ng/L and 22 ng/L in the presence of Methylobacterium mesophilleum with minimal phosphate-buffered saline medium and 0.01% peptone medium, respectively(1). Methyl isobutyl ketone concentrations of 37.8 and 44.7 ug/cu m inside a new and 3-yr old vehicles of identical make and assembly, respectively(2). Methyl isobutyl ketone concentrations of 0.08, 0.15, 0.19, trace and 0.06 nL/L were measured in corn silage, alfalfa silage, total mixed ration feed, almond hulls and almond shells, respectively(3).

Methyl isobutyl ketone's production and use as a solvent for gums, resins, nitrocellulose, paints, varnishes, and lacquers, denaturant agent for rubbing alcohol, in the manufacture of methyl amyl alcohol and in dry-cleaning preparations may result in its release to the environment through various waste streams. Its use as an extracting agent for the production of antibiotics and for the removal of paraffins from mineral oil for the production of lubricating oils may also result in its release to the environment through various waste streams. Methyl isobutyl ketone has been reported found in camphor, elderberry, ginger and Chinese quince. If released to air, a vapor pressure of 19.9 mm Hg at 25 °C indicates methyl isobutyl ketone will exist solely as a vapor in the atmosphere. Vapor-phas...

irritation eyes, skin, mucous membrane; headache, narcosis, coma; dermatitis; In Animals: liver, kidney damage

Eyes, skin, respiratory system, central nervous system, liver, kidneys

LC50 (rat) = 100,000 mg/m3

ACGIH Carcinogen - Confirmed Animal.

inhalation, ingestion, skin and/or eye contact

IDENTIFICATION AND USE: Methyl isobutyl ketone (MIBK) is a colorless liquid. It is used as a solvent for gums, resins, nitrocellulose, paints, varnishes, and lacquers. It is also used as denaturant for rubbing alcohol, in the manufacture of methyl amyl alcohol, and in dry-cleaning preparations. It is also widely used in rubber chemicals for the production of tyres. HUMAN STUDIES: Symptoms and signs of poisoning include: irritation of the eyes, skin, and respiratory tract, as well as CNS depression. Gastrointestinal pain and hepatic toxicity may occur with exposure to high concentrations. In workers exposed to up to 2050 mg MIBK/cu m (500 ppm) for 20-30 min per day and to 328 mg/cu m (80 ppm) for much of the remainder of the working day, over half of the 19 workers complained of weakness...

Oral Subchronic Chronic Reference Dose Reference: HEAST Current

Summary: Exposure to methyl isobutyl ketone resulted in nonneoplastic lesions of the kidney characteristic of α2u-globulin accumulation in male rats and nephropathy in female rats.

Soil Saturation Concentration (mg/kg): 3.36e+03

Male rat-specific kidney tumors can occur after exposures to a structurally diverse group of substances or their metabolites. This arises from binding to α2u, a low-molecular-weight protein. Examples of these substances include 1,4-dichlorobenzene (and -2,5-dichlorophenol, its metabolite), d-limonene (and d-limonene 2-5-oxide, its metabolite), methyl isobutyl ketone (MIBK), 2,2,4-trimethylpentane, (and 2,4,4-trimethyl-2-pentanol, its metabolite), tertiary butyl alcohol (TBA), ethyl tertiary butyl ether (ETBE) (and TBA, its metabolite), and methyl tert-butyl ether (MTBE) (and TBA, its metabolite). They induce α2u-globulin nephropathy, a mode of action (MoA) noted in a series of studies and publications over recent decades as not being relevant in humans. The nephropathy can lead to kidne...

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Use proparacaine hydrochloride to assist eye irrigati...

Soil Saturation Concentration (mg/kg): 3.36e+03

Reference: Smith, C.D. and Nowell, L.H., 2024. Health-Based Screening Levels for evaluating water-quality data (3rd ed.). DOI:10.5066/F71C1TWP