Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 5 (2008) / Chapter Skim
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2 C3 to C8 Aliphatic Saturated Aldehydes
2 C3 to C8 Aliphatic Saturated Aldehydes
Pages 34-47
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From page 34... ...
Toxicology Group Habitability and Environmental Factors Division Johnson Space Center National Aeronautics and Space Administration Houston, Texas BACKGROUND Spacecraft maximum allowable concentrations (SMACs) of C3 to C8 straight-chain, aliphatic aldehydes have been established and were documented in Volume 4 of Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants (James 2000)
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From page 35... ...
The toxicological end points of concern identified previously include mucosal irritation, nasal-cavity injury, nausea and vomiting, and liver damage. SMACs for each exposure time were selected based on the most conservative acceptable concentration (AC)
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From page 36... ...
= 13 ppm (2) Protection Against Nasal-Cavity Injury Long-term studies of isobutanal exposure in rats and mice were used to estimate ACs protective for injury to the nasal cavity (squamous metaplasia and olfactory epithelial degeneration in the nose)
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From page 37... ...
since 2000 with a bearing on C3 to C8 aliphatic saturated aldehydes SMACs were located during this assessment. ADDITIONAL CONSIDERATION OF NONTOXIC ODOR THRESHOLD The group of C3 to C8 aliphatic saturated aldehydes have different odors, described as agreeably fruity to choking and suffocating (Furia and Bellanca 1975; Furia 1980; U.S.
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From page 38... ...
. Table 2-4 summarizes reported odor characteristics for the C3 to C8 aliphatic saturated aldehydes.
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Amoore and Hautala (1983) classified both acetaldehyde and pentanal as "Class A" substances, which can serve as bellwether indicators because their odor threshold values are much lower than their threshold limit values.
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From page 40... ...
based on the assumption that a threshold dose, below which no liver pathology would occur, had been established. However, upon reevaluation, the acute exposure protocol and the now questioned relationship between cellular vacuoles and liver pathology eliminated use of the NOAEL reported by Gage as a point of departure for the longer-term SMACs.
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From page 41... ...
TABLE 2-5 SMACs for C3 to C8 Aliphatic Saturated Aldehydes, 2008 Duration ppm mg/m3 Toxic End Point to Avoid 1h 45 113 Mucosal irritation 24 h 45 113 Mucosal irritation 7d 5 11.8 Nasal-cavity injury 30 d 5 11.8 Nasal-cavity injury 180 d 5 11.8 Nasal-cavity injury 1,000 d 5 11.8 Nasal-cavity injury Note: A representative average odor threshold concentration for the C3 to C8 aliphatic saturated aldehydes is 0.028 ppm (pentanal) (Amoore and Hautala 1983)
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From page 42... ...
The most sensitive end point for severity was for olfactory epithelium degeneration in male rats. The benchmark response corresponding to an average severity grade of 1 (minimal effect)
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The most sensitive end point (lowest BMCL5 = 150 ppm) occurred for respiratory epithelium squamous metaplasia in female rats (Table 2-7)
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. COMPARISON WITH OTHER AIR-QUALITY LIMITS Exposure guidelines for a limited subset of C3 to C8 aliphatic saturated aldehydes exist with various public health and occupational health entities as well as with industry and government advisory bodies.
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Abbreviations: ACGIH, American Conference of Governmental Industrial Hygienists; AIHA, American Industrial Hygiene Association; NIOSH, National Institute for Occupational Safety and Health; REL, recommended exposure limit; TLV, threshold limit value; TWA, time-weighted average; WEEL, workplace environmental exposure level. The current NASA 1- and 24-h SMACs are very similar to exposure levels from other organizations at comparable exposure durations.
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From page 46... ...
1983. Odor as an aid to chemical safety: Odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air water dilution.
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1984. Sensory irritation structure-activity study of inhaled aldehydes in B6C3F1 and Swiss-Webster mice.
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