Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 5 (2008) / Chapter Skim
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5 n-Butanol
5 n-Butanol
Pages 73-84
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From page 73... ...
Toxicology Group Habitability and Environmental Factors Division Johnson Space Center National Aeronautics and Space Administration Houston, Texas BACKGROUND AND SUMMARY OF ORIGINAL APPROACH The alcohol n-butanol is consistently found in International Space Station (ISS) atmospheric samples at concentrations below 0.1 part per million (ppm)
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From page 74... ...
CHANGES IN FUNDAMENTAL APPROACHES RECOMMENDED BY THE NATIONAL RESEARCH COUNCIL The toxicity database on n-butanol was, and still is, sparse and not suitable for any of the approaches sanctioned by the National Research Council such as benchmark dose analyses or the "ten Berge" approach for time-dose extrapolations. For example, the human exposure data on irritancy come from three human studies published in the 1940s, and they give only a general idea of the exposure level at which most people would cease to experience irritation.
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From page 75... ...
Because this "noxious odor" event forced the crew to take refuge in the Russian segment of the ISS for 30 h, it suggests that we must rethink the importance of odor for space operations. TABLE 5-1 SMACs Set in Volume 3 for n-Butanol Safe Concentration Exposure Time mg/m3 ppm Effect to Avoid 1h 150 50 More than mild eye irritation 24 h 80 25 More than mild eye irritation 7d 80 25 Eye irritation, systemic injury 30 d 80 25 Eye irritation, systemic injury 180 d 40 12 Systemic injury, eye irritation Source: James 1996.
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From page 76... ...
Their findings revealed primarily an effect on blood cells in samples from the tail vein as shown in Table 5-2. These inhalation results are compared with results from a gavage study of equal length done earlier in another laboratory (TRL 1986)
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From page 77... ...
b P < 0.01 statistically significant difference compared with controls. Abbreviations: Hct, hematocrit; HgB, hemoglobin; RBC, red blood cells; WBC, white blood cells.
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From page 78... ...
Thus, we must conclude that inhalation of a specific concentration of n-BA results in higher blood concentrations of n-butanol than inhalation of the same concentration of n-butanol. Thus, the data of David et al.
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From page 79... ...
Ototoxicity This adverse effect was not considered in the original SMAC document; however, for completeness it is noted here that an old report of ototoxicity that some groups had used to set human exposure limits has been superseded by more recent findings (Velazquez et al.
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From page 80... ...
Hematotoxicity and Immunotoxicity Based on the information presented in Table 5-2, we will not do a risk assessment on the apparent hematologic and immune effects suggested by the inhalation study of Korsak et al.
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From page 81... ...
The 1-h SMAC and the NIOSH ceiling limit are the same. RECOMMENDATIONS FOR ADDITIONAL RESEARCH A detailed review of the odor threshold work, which is beyond the scope of this review, might suggest a more focused statement about odor thresholds and noxious concentrations; however, one is plagued by anecdotal reports from crew that odor perceptions in space can be quite different than on the ground.
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From page 82... ...
rule SMACs 150 80 80 80 40 40 a The only value that has changed from the original SMACs is the addition of the 1,000-d value. b The odor threshold and noxious odor concentrations are uncertain.
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From page 83... ...
1983. Odor as an aid to chemical safety: Odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water diulution.
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From page 84... ...
1986. Rat Oral Subchronic Toxicity Study of Normal Butanol.
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