Toxicological Sciences, Vol 48, 255-263, Copyright © 1999 by Society of Toxicology
S Kumagai, H Oda, I Matsunaga, H Kosaka and S Akasaka
Respiratory uptake was investigated for 10 polar organic solvents with high
blood/air partition coefficients (lambda(blood/air)): ethyl acetate
(lambda(blood/air), 77), methyl iso-butyl ketone (90), methyl acetate (90),
methyl propyl ketone (150), acetone (245), iso-pentyl alcohol (381),
iso-propyl alcohol (848), methyl alcohol (2590), ethylene glycol monobutyl
ether (EGBE, 7970), and propylene glycol monomethyl ether (PGME, 12380).
Test-air concentrations (Cinh) were 25 to 200 ppm. Four healthy male
volunteers inhaled the test air for 10 min at rest and then room air for 5
min. The percentage of solvent in the end-exhaled air and in the
mixed-exhaled air increased after the start of the test-air respiration,
and reached a quasi-steady-state level within a few min. The speeds of
these increases at the start of the test-air respiration became lower as
lambda(blood/air) increased. The mean uptakes (U) for the last five min of
the test air respiration were 67.3, 52.9, 60.4, 53.0, 52.6, 63.0, 60.3,
60.8, 79.7, and 81.3%, respectively, for ethyl acetate, methyl iso-butyl
ketone, methyl acetate, methyl propyl ketone, acetone, iso-pentyl alcohol,
iso-propyl alcohol, methyl alcohol, EGBE and PGME. Thus, U values of the
alcohols were higher than those of the ketones and lower than the glycol
ethers. The overall view, except for esters, showed that U increased with
lambda(water/air) increases. This tendency can be explained by a hypothesis
that solvent absorbed in the mucus layer of the respiratory tract is
removed by the bronchial blood circulation. U values of ethyl acetate and
methyl acetate were higher than those of methyl iso-butyl ketone and methyl
propyl ketone, though the lambda(blood/air) values of these esters were
nearly equal to those of the ketones. For the respiration of the esters,
their metabolites, ethyl alcohol and methyl alcohol, were detected in the
exhaled air. The exhalation percentage of the metabolites increased after
the start of test-air respiration and reached a quasi-steady-state level of
2 and 3%, respectively, by the 5th min. These data suggest that removal of
the solvent via metabolism in the wall tissue of the respiratory tract
plays an important role for the esters.
ARTICLES
Uptake of 10 polar organic solvents during short-term respiration
Department of Occupational Health, Osaka Prefectural Institute of Public Health, Japan.
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