Methyl tertiary butyl ether (MTBE) is widely used in gasoline as an ox
ygenator and octane enhancer. There is also an interest in using the e
thyl tertiary butyl (ETBE) and methyl tertiary amyl (TAME) ethers. we
measured the blood, water, and olive oil/air partition coefficients in
vitro of MTBE, ETBE, TAME and tertiary butyl alcohol (TEA), a metabol
ite of MTBE and ETBE. The results indicate similar uptake and distribu
tion behavior Tar the three ethers and a slight affinity for fatty tis
sues. The partition coefficients of TEA indicate that this metabolite
is not excreted via the lungs to any great extent and that it is prefe
rentially distributed in body water. Further, we exposed 10 healthy ma
le volunteers to MTBE vapor at 5, 25 and 50 ppm for 2 h during light p
hysical exercise. Uptake and disposition were studied by measuring MTB
E and TEA in inhaled and exhaled air, blood and urine. Low uptake, hig
h post-exposure exhalation, and low blood clearance indicate slow meta
bolism of MTBE relative to many other solvents. A low recovery of TEA
in urine (below 1% of uptake) indicates further metabolism of TEA. The
concentration of MTBE and TEA in blood was proportional to exposure l
evel suggesting linear kinetics up to 50 ppm. The half life of 7-10 h
in blood and urine indicates that TEA would be more suitable than the
parent compound as a biomarker for MTBE exposure. Subjective ratings (
discomfort, irritative symptoms, CNS effects) and eye (redness, tear f
ilm break-up time, conjunctival damage, blinking frequency) and nose (
peak expiratory flow, acoustic rhinometry, inflammatory markers in nas
al lavage) measurements indicated no or minimal effects of MTBE.