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IRIS Toxicological Review and Summary Documents for Methyl Tert-Butyl Ether (MTBE)
Citation:
U.S. EPA. IRIS Toxicological Review and Summary Documents for Methyl Tert-Butyl Ether (MTBE). U.S. Environmental Protection Agency, Washington, DC.
Impact/Purpose:
The U.S. EPA is conducting a new health assessment of MTBE that will appear on the Agency's online database, the Integrated Risk Information System (IRIS). IRIS is an EPA database containing Agency scientific positions on potential adverse human health effects that may result from chronic (or lifetime) exposure to chemicals in the environment. IRIS contains chemical-specific summaries of qualitative and quantitative health information in support of two steps of the risk assessment process, i.e., hazard identification and dose-response evaluation. IRIS assessments are used in combination with specific situational exposure assessment information to evaluate potential public health risks associated with environmental contaminants.
Description:
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.