Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 2 (1996) / Chapter Skim
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B9 Methyl Ethyl Ketone
B9 Methyl Ethyl Ketone
Pages 307-330
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From page 307... ...
is a flammable, colorless liquid with an acetone-like odor (ACGTH, 19911. Synonyms: Formula: CAS number: Molecular weight: Boiling point: Melting point: Vapor pressure: Conversion factors at25°C,latm: 2-butanone, methyl acetone CH3COCH2CH3 78-93-3 72 79.6°C 85.9°C 71.2 mm Hg at 20°C 1 ppm = 2.94 mg/m3 1 mg/m3 = 0.34 ppm OCCURRENCE AND USE MEK is used as a solvent in synthetic resins manufacturing and in the surface-coating industry (ACGTH, 19911.
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From page 308... ...
. At the end of the 4-h MEK exposure at 200 ppm, the venous blood concentration reached 80 ,umol/L (5.8 ,ug/mL~)
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From page 309... ...
One and a half hours after a 4-h MEK exposure at 200 ppm, the venous blood concentration of MEK dropped from 3.5 ,ug/mL to 1.0 ,L~g/mE, and it decreased to below detectable concentrations 20 h after exposure in 22 volunteers (Dick et al., 1988~. [n guinea pigs given MEK intraperitoneally at 450 mg/kg (a much higher dose than the estimated dose of 28 mg/kg used in the inhalation study by Liira et al.
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in the study, MEK at a concentration of 100 ppm resulted in slight nose and throat irritation. Mild eye irritation was reported by some subjects at 200 ppm.
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It can be concluded that a subchronic MEK exposure could have a mild effect on the liver. In the same study, MEK at 5000 ppm decreased the SGPT slightly, and it increased the serum potassium, glucose, and alkaline phosphatase levels in the females.
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In a retrospective cohort mortality study of 14,067 aircraft manufacturing workers who have spent, on the average, 15.S y in the facility, there was no significant excess of mortality from cancer of various organs (Garabrandt et al., 19881. These workers were exposed to various substances on their jobs, including aluminum alloy dusts, welding fumes, methylene chloride, trichioroethylene, MEK, lubricating oils and greases, and metal cutting fluids (Garabrandt et al., 19881.
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From page 313... ...
MEK exposure at 3000 ppm for 7 hid on gestation days 6-15 is slightly toxic to the fetus by delaying ossification in the rat and reducing fetal weight in the mouse (Deacon et al., 1981; Schwetz et al., 19911. It also decreased the body-weight gain and increased the water consumption in the pregnant rats (Deacon et al., 1981)
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From page 314... ...
and decreased blood concentrations of 2,3-butanedio! (Liira et al., 199Ob)
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METHYL ETHYL KETONE 3 ~ 5 In conclusion, the interaction findings indicate that NASA needs to be aware of the possibility that ethanol ingestion might potentiate MEK's toxicity and MEK inhalation could potentiate the toxicity of n-hexane, methyl n-buty! ketone, and m-xylene during combined exposure.
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317 => A _ ~Hi Ce ^ ^ ~Cd By 3,, c em, a I, Hi ~E x C ~ ~' | ~ ~i ~ c ~.
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From page 318... ...
318 in: .S s Cal Cal a)
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The NRC's Committee on Toxicology advised that MEK's SMACs need not be set using hepatomegaly as an end point because of doubtful cTinical significance of a mild increase in liver weight absent any histological hepatic damages. Accordingly, ACs are derived for only mucosal irritation and CNS impairment.
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1-h and 24-h ACs based on mucosal irritation = mildly to moderately irritating level x 1/extrapolation factor = 100 ppm x I/2 = 50 ppm.
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From page 321... ...
A pharmacokinetic technique is used to predict an MEK concentration in blood during an inhalation exposure of humans to MEK. By assuming that MEK's CNS effect is dependent on its concentration in the blood, the pharmacokinetic technique can predict an acceptable exposure concentration based on the prevention of CNS impairment.
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From page 322... ...
With MEK, for instance, the expired MEK concentration was about 53 % of the inhaled MEK concentration all through a 4-h exposure of human subjects at 200 ppm, indicating that the MEK absorption rate remained constant through at least 4 h of an inhalation exposure. It is, therefore, safe to assume that the blood concentration of the vapor will be no higher than the concentration predicted by the formula above.
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From page 323... ...
Because it only takes an MEK exposure of 9.5 h for the blood concentration to reach steady state, the ACs based on CNS impairment for 24 h, 7 4, 30 it, and 180 ~ are all estimated to be 180 ppm. The 1-h AC can be derived as follows: The pharmacokinetic formula shows that, during an inhalation exposure to MEK, the MEK concentration in blood reached in 1 h should be 40% of that reached in 4 h.
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From page 324... ...
324 TO ~ ~ 4~ ~ Jocose irrhabon and CNS i-airmen1 shows 1b~ the lab, 24-b, 7-d, SO-d, and 180-d Sh4ACs are set at 50, 30, 10, 10, and 10 ppm, respecdvely. Because ~itber grunion nor CNS i~hme~ ~ expected to be affected by microgravity-induced physiological cues, no micrograv~y a~ustmems are needed far the ShlACs.
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From page 325... ...
325 C ~ o o == Cal an Cut go Cd .= sit Cal g .~ so Cal Cal Cal V, = PA A A .S Em o z C)
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From page 326... ...
1983. A 90-day vapor inhalation toxicity study of methyl ethyl ketone.
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1988a. Kinetics of methyl ethyl ketone in man: absorption, distribution and elimination in inhalation exposure.
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1991. Developmental toxicity of inhaled methyl ethyl ketone in Swiss mice.
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1981. Changes in rat liver microsomal cytochrome P-450 and enzymatic activities after inhalation of n-hexane, xylene, methyl ethyl ketone and methy~chIoroform for four weeks.
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