Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 2 (1996) / Chapter Skim
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B10 Nitromethane
B10 Nitromethane
Pages 331-350
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From page 331... ...
Nitromethane is not known to be used in spacecraft, but it has been predicted to be off-gassed in the Space Station Freedom (Leban and Wagner, 1989~.
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From page 332... ...
Incubation of nitromethane with rat liver microsomes under oxidative conditions has been shown to produce nitrite in one study (Marietta and Stuehr, 1983) and to form nitrite and formaldehyde in a stoichiometric fashion in another study (Sakurai et al., 1980~.
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From page 333... ...
The lethal responses of the two rabbits and two guinea pigs combined varied with concentration x time (C x T)
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From page 334... ...
They reported that it took exposures at 3% or 5% nitromethane for more than ~ h or 1% nitromethane for 5 h or more to cause CNS symptoms in rabbits and guinea pigs. Hepatic Toxicity Weatherby (1955)
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From page 335... ...
also had doubtful meaning in inhalation exposures of nitromethane because Griffin (1990) also did not detect any increases in the level of alanine transaminase, aspartate transaminase, bilirubin or protein, or any hepatic histopathology in rats exposed to nitromethane at 100 or 200 ppm, 7 in/d, 5 d/w, for 2 y.
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From page 336... ...
No thyroid weight or thyroxine level changes were detected in 10 rats exposed at 98 or 745 ppm, 7 in/d, 5 d/2, for 2 6, 10 d, 1 mo, or 3 mot Similarly, no thyroid weight or thyroxine level changes were found in five rabbits exposed to nitromethane at 98 ppm, 7 in/d, 5 d/w, for 1 or 3 mo (Lewis et al., 19791. The thyroid data of Lewis et al.
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From page 337... ...
They observed moderate to moderately severe focal lung hemorrhages and congestion, associated with interstitial lung edema, in rabbits exposed to nitromethane at 745 ppm, 7 in/d, 5 d/w, for ~ mot The interstitial pulmonary edema evidently must not be severe because no increase in the wet-weight-todry-weight ratio was found in the lung of these rabbits. These changes in the pulmonary morphology were absent in the rabbits exposed to nitromethane at 98 ppm.
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From page 338... ...
Intraperitoneal injections of nitromethane with 0.5 mL (equivalent to 46 ma) every third day, begun 1 w before the rats were bred and continued throughout gestation, failed to produce any changes in the percentage of successful matings, litter size, pup death rate, birth weights, or maternal behavior (Whitman et al., 19771.
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From page 339... ...
Develonmental Toxicity No data on nitromethane's developmental toxicity were found in the Toxline and Toxlit databases of the National Library of Medicine. Interaction with Other Chemicals No data on nitromethane's interaction with other chemicals were found.
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From page 340... ...
340 PA V, V, 'Cry C ~ .~ o Cd ·X Levi 0 a ~ O £ 0 cr An ~_ ~ _ -0 _ _ ~_ _ c> A^ ~ 3 ~:; 3 3 r ~ ~ · ~ ~, I ~ ~i ~ C O ~ ~ C it, o 0 ~ of, =3 C C: Z pi, 'C C ~ on ~ 3 3 ct = ~- ^ 11 ._ ._ ~ cot ct ~ ~ cd can Per'= ~ c ~ ~ O :> ~3 }^ ^ O ~ 5 `~' - O t ~ 5 ~ the O-^ 1 - > ~t-~ ~ O O sol O O ~ ' oo oo O O ~
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From page 341... ...
341 ~at at ~_ _ CeCal _ ._._ ._ 33 3 Cal .m ~3 5 e - ~ 3< ~- =' e ~ c e D 5 e X D E 5 D ~ E ~ ~ D C ~ ~ U E ° _ o c 0 ~ c ~ c 0 ~ c .c c cow E ~ ~ 5 ~ 50 0 ° O ~ ~ 5, ~== 5 C 5 E Do ~, o E ~ 0 ADS ~ -= ~ C)
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From page 342... ...
342 I: .S s LC m Cal Cal C) LL1 ._ Cal ~ 5= 3 0 U: ·O Ct =~1 o~ =0 ._ Ct SI: O ~ OOOO OOOOOO d" ~fit ~d"d"d" catcrycr cr ~Ad ____ ______ ....
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From page 343... ...
RATIONALE FOR ACCEPTABLE CONCENTRATIONS The SMACs are set to protect the astronauts against the following toxic end points: CNS symptoms and anemia. For a given exposure duration, the SMACs are set by selecting the lowest acceptable concentration (AC)
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From page 344... ...
I-h, 24-h, 7-d, 30-d, and 180-d ACs based on CNS symptoms = 90-d NOAEL x 1/species factor = 745 ppm x 1/10 = 75 ppm. The 180-d AC based on CNS symptoms is set equal to the 30-d AC because if CNS symptoms fad!
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From page 345... ...
Haber's rule is used to derive the 24-h AC. 24-h AC based on anemic effects = 2-d NOAEL x time adjustment x 1/species factor x 1/microgravity factor = 745 ppm x (7 h/d x 2 d)
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From page 346... ...
7-d and 30-d ACs based on anemic effects = 2-y NOAEL x 1/species factor x 1/microgravity factor =200 ppmx 1/10x 1/3 = 7 ppm. 180-d AC based on anemic effects = 2-y NOAEL x time adjustment x 1/species factor x 1/microgravity factor 200 ppm x (7 hid x 5 d/w x 104 w)
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From page 347... ...
, the lower 95 % confidence limit of the LDso is estimated to be 0.49 %-h. Acceptable C x T based on lethality for acute exposure = Benchmark dose x 1/species factor =0.49%-hx 1/10 = 490 ppm-h.
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From page 348... ...
348 V, o ._ Ct it, Cal o Ct C)
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From page 349... ...
1989. Space Station Freedom Gaseous Trace Contaminant Load Model Development.
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From page 350... ...
1980. The interaction of aliphatic nitro compounds with the liver microsomal monooxygenase system.
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