Methyl tert-butyl ether (MTBE)

Overview

MTBE is a volatile organic chemical used to oxygenate gasoline. Oxygenated gasoline improves the exhaust emissions from gasoline engines. Since 1992 it has been used to comply with the Federal Reformulated Gasoline (begun in 1995) and Wintertime Oxygenated Fuel (begun in 1992) programs under the Clean Air Act. A total of 26 States have areas required to participate in these programs. Although some evaporates, MTBE moves readily through soil into water and degrades more slowly than many other gasoline components. This is a particular problem when MTBE containing gasoline is stored in underground tanks and the tanks leak. This assessment evaluates the potential health risks of MTBE in light of the available information and will characterize the key cancer and non cancer health effect hazards from inhalation and oral exposure. This will update a 1993 IRIS RfC, but will be the first entry for an RfD and a cancer characterization.