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TABLE 5-1 Physical and Chemical Properties of MEK




Chemical name

Methyl ethyl ketone



MEK, 2-butanone, methyl acetone, ethyl methyl ketone,methyl propanone

CAS no.


Molecular weight


Boiling point


Melting point


Liquid density (15°C)

0.805 g/cm3 at 20°C


Vapor pressure (at 20°C)

77.5 mm Hg

Vapor pressure (at 25°C)

90.7 mm Hg

Vapor density



Soluble in water, ether, acetone, benzene


Conversion factors

1 ppm = 2.94 mg/m3 at 25°C

1 mg/m3 = 0.340 ppm

Abbreviations: g/cm3, gram per cubic centimeter; mg/m3, milligrams per cubic meter; mm Hg, millimeters of mercury.

fish, grape, black tea, tomato, and yogurt; its taste has been described as “chemical-like and slightly fruity green.” Average daily per capita intake in the United States via food is estimated to be 1.6 milligrams (mg), mostly from white bread, tomatoes, and cheddar cheese (IPCS 1993).

MEK is not routinely used in spacecraft during flight but could potentially be part of some future payload or a component of utility chemicals, such as adhesives or an off-gassing product from nonmetallic materials. MEK has been found occasionally in trace concentrations (up to 21 micrograms/liter [µg/L]) in potable water on the International Space Station.


Most of the MEK toxicokinetic and metabolism data in the literature involve exposure by inhalation, but many of the toxicokinetic results should hold true for MEK exposures by ingestion as well.


No quantitative data on the extent of absorption of ingested MEK in humans were identified, but case reports indicate that humans absorb enough MEK after ingestion of unknown quantities to cause systemic toxicity, including unconsciousness and metabolic acidosis (Kopelman and Kalfayan 1983). Nine

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