Ethyl tertiary-butyl ether (
ETBE) is an oxygenated
gasoline additive synthesized from
ethanol and
isobutene that is used to reduce CO2 emissions. To support the Kyoto Protocol, the production of
ETBE has undergone a marked increase. Previous reports have indicated that exposure to
ETBE or methyl tertiary-butyl
ether resulted in liver and kidney
tumors in rats and/or mice. These reports raise concern about the effects of human exposure being brought about by the increased use of
ETBE. The present study was conducted to evaluate the genotoxicity of
ETBE using micronucleus induction of polychromatic erythrocytes in the bone marrow of male and female rats treated with
ETBE in the
drinking-water at concentrations of 0, 1,600, 4,000 or 10,000 ppm or exposed to
ETBE vapor at 0, 500, 1,500 or 5,000 ppm for 13 weeks. There were no significant increases in micronucleus induction in either the
drinking water-administered or inhalation-administered groups at any concentration of
ETBE; although, in both groups red blood cells and
hemoglobin concentration were slightly reduced in the peripheral blood in rats administered the highest concentration of
ETBE. In addition, two consecutive daily
intraperitoneal injections of
ETBE at doses of 0, 250, 500 or 1,000 mg/kg did not increase the frequency of micronucleated bone marrow cells in either sex; all rats receiving
intraperitoneal injections of
ETBE at a dose of 2,000 mg/kg died
after treatment day 1. These data suggest that
ETBE is not genotoxic in vivo.