Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 2 (1996) / Chapter Skim
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B12 Toluene
B12 Toluene
Pages 373-393
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B12 Toluene Hector D Garcia, Ph.D.
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. A linear relationship was found between toluene concentrations in alveolar air and arterial blood in human subjects exposed to toluene at 100, 300, 500, and 714 ppm for 20 min per concentration (Gamberale and Hultengren, 1972~.
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, which are excreted in the urine (Benignus et al., 1981~. Possible ethnic differences in toluene metabolism were reported for Chinese, Turkish, and Japanese solvent workers; the mate Japanese excreted almost twice as much hippuric acid as the male Chinese under similar exposure conditions, although the difference was less marked between female Chinese and Japanese workers, and there were no differences in the excretion of o-cresol (Inoue et al., 1986~.
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subjects showed a statistically significant 1 % decrease in manual dexterity, decreased color discrimination, and sTightly decreased accuracy in visual perception compared with unexposed naive controls (Baelum et al., 1985~.
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Subchron~c and Chronic Toxicity Histopathology, Clinical Chemistry, and Hematology A well-executed chronic inhalation study in F344 rats performed by the Chemical industry Institute of Toxicology in 1980 failed to show any adverse effects at the doses tested (Gibson et al., 1983~. Groups of 120 male and 120 female F344 rats were exposed to toluene at 30, 100, or 300 ppm ~ > 99.98% pure)
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Lethality In an extensive study conducted by the National Toxicology Program (NTP) on nonpregnant animals, mice (n = 120)
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A study examining occupational exposure to chemicals in the workplace compared 301 working women who had recently given birth to a child with congenital defects with 301 matched working women whose most recent child was born normal (McDonald et al., 19871. The authors' analysis indicated that, of nine categories of chemical exposures examined, only in those women exposed to aromatic solvents, primarily toluene, were there a suspicious excess number of cases of defects.
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A drastic increase in toluene concentration in the blood of rats was reported after combined inhalation with acetone (Freundt and Schneider 1986~. Inhalation of toluene at 954 ppm by pregnant rats combined with acetyIsalicylic acid at 500 mg/kg resulted in increased maternal and fetal toxicity and teratogenicity (Tatrai et al., 1979~.
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381 en ._ C)
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382 is .S C)
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for any adverse effect at each exposure duration using guidelines established jointly by the National Research Council and NASA (NRC, 1992~. The evidence and logic used to determine
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, except possibly after chronic exposure to high concentrations, indicating that the effects are dependent on blood concentrations but not exposure duration. Pharmacokinetic experiments have shown that arterial blood concentrations reach 60% of maximum in 10
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of 100 ppm, the ACs have been set using the study that yields the lowest values of the ACs: In 16 young subjects, exposure at 10 or 40 ppm for 6 h did not result in any adverse effects for any of the end points examined (nasal mucus flow, lung function, subjective response, and psychometric performance) , but exposure at 100 ppm produced irritation of eyes and nose and borderline significance in reduced performance in a battery of eight psychometric tests for visual perception, vigilance, psychomotor functions and higher cortical functions (Andersen et al., 1983~.
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In rabbits, continuous exposure at 266 ppm for gestation days 615 caused a decrease in maternal-weight gain and a slight, but not statistically significant, increase in spontaneous abortion (Ungvary and Tatrai, 1985~. ~ study of spontaneous abortion rates in the wives (n = 28)
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and using a species extrapolation factor of 10, the 30-d and 180-d ACs are the following: 30-d AC based on lethality = NOAEL x 1/species factor = 1200 ppm x 1/10 = 120 ppm. 180-d AC based on lethality = NOAEL x time adjustment x 1/species factor = 1200 ppm x (140 d/180 d)
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Studies using such validated tests should include measurements at several vapor concentrations and with and without exercise at light and heavy workloads. Although the data would not be applicable to spaceflight under current NASA guidelines, which prohibit spaceflight by pregnant astronauts, more data are needed on the developmental and reproductive toxicity of inhaled toluene, particularly with regard to teratogenicity and spontaneous abortion.
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1986. The effect of toluene inhalation exposure on catecholamine content of rat sympathetic neurons.
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1986. Drastic increase of the m-xylene or toluene concentrations in blood of rats after combined inhalation with acetone.
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1992. Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants.
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1989. Spontaneous abortions and congenital malformations among the wives of men occupationally exposed to organic solvents.
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