MTBE in Gasoline: Clean Air and Drinking Water Issues

Publication Date: May 2005

Publisher: Library of Congress. Congressional Research Service

Author(s):

Research Area: Energy; Environment

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Abstract:

The 109th Congress continues efforts to address fuel policy and health and environmental issues related to the use of the gasoline additive methyl tertiary butyl ether (MTBE). Concern over water contamination caused by MTBE has raised questions concerning the desirability of using the additive as a means of producing cleaner-burning fuel. MTBE has been used by most refiners to produce the reformulated gasoline (RFG) required under the Clean Air Act in portions of 17 states and the District of Columbia. It is credited with producing marked reductions in carbon monoxide emissions; RFG has also reduced emissions of toxic substances and the volatile organic compounds that react with other pollutants to form smog. However, incidents of drinking water contamination by MTBE have raised concerns and led to calls for restrictions on its use. In 1999, Governor Davis of California ordered a phaseout of MTBE use by December 31, 2002 (later amended to December 31, 2003). Eighteen other states, including New York and Connecticut, now have enacted limits or phaseouts of the substance.

EPA responded to initial reports of water contamination in the mid-1990s by intensifying research and focusing on the need to minimize leaks from underground fuel tanks. However, contamination incidents increased, and in March 2000, EPA began the process of requiring a reduction or phaseout of MTBE use under the Toxic Substances Control Act. Because regulatory action could take years to complete, EPA urged Congress to amend the Clean Air Act to provide specific authority to reduce or eliminate use of MTBE. In the 109th Congress, the House has included such authority in H.R. 6, the comprehensive energy bill. The bill would ban the use of MTBE by December 31, 2014, with some exceptions, and would provide extensive assistance for MTBE producers, including a controversial "safe harbor" from product liability lawsuits. The Congressional Budget Office identified the latter provision as an intergovernmental mandate under the Unfunded Mandates Relief Act, thus making the provision subject to a point of order; however, the House voted to retain the safe harbor provision on a separate vote. In the Senate, the Environment and Public Works Committee has approved S. 606, which would ban MTBE within four years of enactment, and would not provide a safe harbor for MTBE producers.

If MTBE were removed from gasoline without amending the Clean Air Act, refiners would need to use alternative sources of oxygen in RFG. The potential alternatives are other forms of ether, or alcohols such as ethanol. Ethanol is the most likely substitute, but it costs more to produce than MTBE, it poses challenges to the gasoline distribution system, and some studies suggest that it increases the risk of water contamination compared to non-oxygenated gasoline. Gasoline that meets the performance requirements for RFG without using oxygenates at all can be made, but current law requires the use of oxygenates in RFG.

The principal issues for Congress are whether MTBE use should be limited or phased out, and whether there should be a "safe harbor" from product liability lawsuits for gasoline refiners and marketers who have used MTBE. This report reviews MTBE issues and will be updated.