Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 1 (1994) / Chapter Skim
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B1: Acetaldehyde
B1: Acetaldehyde
Pages 19-38
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From page 19... ...
BY Acetaldehyde King Lit Wong, Ph.D. Johnson Space Center Toxicology Group Biomedical Operations and Research Branch Houston, Texas PHYSICAL AND CHE1\`IICAL PROPERTIES Acetalclehycie is a colorless liquid with a fruity, pungent odor (Sax, 1984)
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The respiratory rate also inversely affected acetaldehyde's respiratory retention. At an exposure concentration ranging from 84 to 336 ppm, He percent retention of acetaIdehyde linearly decreased by 25 as He respiratory rate was increased from 5 to 40 bpm (Egle, 19701.
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In this mouse model, a chemical's sensory irritancy slows down He breading via a trigeminal nerve reflex (Alarie, 1973~. Acetaldehyde at 2845 ppm reduced He mouse's respiratory rate by 50% in 10 min.
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be formed in the nasal respiratory mucosa after a 6-h exposure and olfactory mucosa after five daily 6-h exposures of rats to acetaldehyde at 1000 ppm (Lam et al., 1986~. Lethality Acetaldehyde is lethal at sufficiently high exposure levels.
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Pulmonary and Renal Toxicity In addidon to injuring Me nose, subchronic acetaldehycle exposures have been shown to affect the lung and kidney. A 5-w exposure of rats to acetaldehyde at 243 ppm, ~ in/d, 5 d/w produced increases in functional residual capacity, residual volume, total lung capacity, and respiratory rate, but no change in forced expiratory mean flows (Saldiva et al., 1985~.
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Other than degeneration, hyperplasia, and metaplasia of the nasal mucosa, they found aclenocarcinomas of the nasal olfactory epithelium and squamous cel1 carcinomas of the nasal respiratory epithelium in both ~e male and female rats. The combined inciclences of nasal adenocarcinomas and squamous cell carcinoma in the male rats were ~ of 49, 17 of 52, 41 of 53, and 36 of 49 in the 0-, 750-, 1500-, anct 30001000-ppm groups, respectively (Woutersen et al., 1986~.
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Acetaldehycle was found to induce sister chromatic exchange in vitro without the addition of S-9 fraction, suggesting that metabolic activation was not required. Acetaldehyde also is known to produce chromosomal aberrations in mammalian cell culture (Bird et al., 1981~.
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27 ~ ~ _ - aa ~ 8 Ed 8 to ~E i~ 3' ~ ~8 ~1 ~ ~ ~ ~i .
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with the corresponding concentrations based on noncarcinogenic end points. The noncarcinogenic end points produced by acetaldebycle include irritation sensation of Me eyes, noncarcinogenic structural changes of nasal mucosa, lung function changes, and increased kidney weight (Silverman et al., 1946; Appelman et al., 1986; Kruysse et al., 1975; Salctiva et al., 1985~.
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It took 243 ppm of acetaldehyde to cause lung function changes in a 5-w repetitive exposure of rats (Saldiva et al., 1985~. In that study, the investigators used only one acetaldehyde exposure concentration.
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24-h exposure level that would yield an excess tumor risk of 10-4 - 0.025 ppm x 26,082 = 660 ppm. For We 7-d, 30-d, and I80-d acceptable exposure levels based on carcinogenesis, adjustment factors are calculated with the approach of the NRC's Committee on Toxicology (NRC, 1990)
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These data were prudently interpreted to mean that a 15-min acetaldehyde exposure at 200 and 50 ppm would probably result in moderate and mild eye irritation, respectively; and some individuals, however, are more sensitive to acetaldebyde's sensory irritation than others, so that 25 ppm is nonirritating except to supersusceptible inctivicluals. Since the I-h SMAC is designed for contingencies, slight eye irritation is acceptable.
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In setting the 24-h AC, a 24-h exposure concentration of acetaldehyde that is one half Me 15-min exposure concentration is assumed to be as irritating as the 15-min concentration. Although there is no direct evidence Mat Me irritancy of acetaldehyde's vapor at 24 h would be the same as Mat at ~ h, data on the irritancy of acrolein and ammonia indicate Mat the irritancy of most sensory irritants reaches a plateau near 1 h.
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Consequently, the same acceptable exposure level based on eye irritation may be used for 7, 30, or I80 cI. To prevent eye irritation in practically all astronauts in a 7-d, 30-d, or 180-d exposure, a correction factor of lO/(square root of n)
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1986. Effect of variable versus fixed exposure levels on the toxicity of acetalclehyde in rats.
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extractabilibr of DNA from proteins in the rat nasal mucosa after acetalclehyde exposure.
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1990. Guidelines for Developing Spacecraft Maximum Allowable Concentration for Space Station Contaminants.
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From page 38... ...
1977. Acetaldehyde formadon during deproteinization of human blood samples containing ethanol.
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