Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 1 (1994) / Chapter Skim
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B8: Methanol
B8: Methanol
Pages 149-168
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From page 149... ...
in off-gas tests of flight hardware (H. Leano, Johnson Space Center, personal commun., 1990~.
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From page 150... ...
It took an amount of aspartame in 36 12-oz cans of diet soft drink to significantly elevate the blood methanol concentration. Therefore, oral intake of diet soda will not significantly contribute to methanol exposure in the astronauts.
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From page 151... ...
at about 93 ppm for several months to 30 years, the venous methanol concentration reached 9 mg/L at He end of the working week, and He urinary methanol and formic acid concentrations were 22 and 30 mg/L, respectively (Heinrich and Angerer, 1982~. Methanol elimination depends on the close.
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From page 152... ...
In addition to causing inebriation, methanol intoxication has been shown to cause a prolonged parkinsonian syndrome with lesions in the putamen in three human cases (Bourrat and Riboullard, 1986; Verslegers et al., 1988; LeWitt and Martin, 1988~. In one of the cases, the intoxication was so severe that the individual developed permanent parkinson~sm with visual impairment, increased dopamine beta-hydroxylase activity ant!
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From page 153... ...
The higher prevalence of blurred vision in He teacher aides did not appear to be due to eye irritation because He increased prevalence of eye burning, itching, and tearing in the teacher aides was not statistically significant compared with that in He teachers (Frederick et al., 1984~. These teacher aides worked from ~ h/w to 40 h/w.
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From page 154... ...
is that working in an environment with methanol at about 1000 ppm could result in blurred vision and headaches. Unfortunately, He NIOSH investigators did not present the methanol concentrations that the teacher aides afflicted why blurred vision or headaches were exposed to versus Hat of the nonre sponding teacher aides.
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From page 155... ...
Methanol is not genotoxic as evidenced by negative finclings in We Ames test, We methanols inability to cause sister chromatic exchange in Chinese hamster ovary cells, and micronuclei in mice (Florin et al., 1980; Obe and Ristow, 1977; Gocke et al., 1981~. Developmental Toxicity UnJike inhaled ethanol, which affects pregnant rats ant!
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156 a, .~ .O o so: V, v so U)
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RATIONALE Methanol's SMACs are set to protect the astronauts against headaches and ocular injury, the two major toxic end points of methanol poisoning. For each desired exposure duration, an acceptable concentration (AC)
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From page 159... ...
, workers complained of headaches when they worked In He vicinity of duplicating machines in which methanol was used. As described in "Toxicity Summary," the LOAEL for headaches is esdmated to be 391 ppm according to the data in He NIOSH study.
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From page 160... ...
According to classical pharmacokinetics, during a continuous exposure at a constant dose rate of a chemical that follows a one- or two-compartment model, the blood concentration will reach 99% of the steady state seven elimination half-lives into Me exposure (Gibaldi and Perrier, 1975~. Since methanol distributes rapidly throughout the body in body water (Yant and Schrenk, 1937)
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From page 161... ...
Such a timeadjustment factor is conservative because it implies that He blood concentradon of formic acid increases linearly with exposure time for 16 h into a methanol exposure. Actually, the blood concentration of formic acid will probably increase in some exponential function to 16 h, but because He data available do not allow for an accurate estimation of the exponential function, a linear function is used instead.
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From page 162... ...
24-h AC Unlike headaches, methanol's occular toxicity might not be entirely dependent on ~e blooci concentration of formic acid and might not have a threshold. Methanol's occular toxicity is prudently assumed to be dependent on the product of exposure concentration and exposure duration.
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From page 163... ...
7-d, 30-d, and 180-c! ACs based on visual disturbances = occupational LOAEL x 1/NOAEL factor x time adjustment x 1/small-e factor = 69 ppm x 1/10 x (40 h/w)
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From page 164... ...
are not used to set the long-term SMACs. Establishment of SMACs The ACs based on headaches and visual disturbances for each of the exposure durations are listed in Table 10-4.
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1987. Severe reversible cardiac failure associated with methanol intoxication.
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1955. Toxicologic considerations in direct process spirit duplicating machines.
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From page 167... ...
1981. Blood methanol concentrations in normal adult subjects administered]
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