n e w s of t h e weeK
GETTING THE MTBEOUT Administration seeks to ban gasoline additive that taints groundwater
C
iting concerns about the environment, low farm commodity prices, and U.S. dependence on imported oil, Clinton Administration officials last week unveiled plans to phase out use of the gasoline additive methyl tert-butyl ether (MTBE) and simultaneously boost sales of ethanol. The Administration is asking Congress to change a Clean Air Act provision that sets the benchmark for oxygen content in reformulated gasoline. This move would eliminate or significantly reduce MTBE use in gasoline. The addition of MTBE increases the oxygen content of gasoline, making the fuel burn cleaner. Use of MTBE has helped improve air quality in a number of cities. However, MTBE is increasingly being found in drinking water supplies, primarily because of leaking underground and aboveground gasoline storage tanks. The substance makes water smell and taste foul even at very low concentrations. EPA classifies MTBE as a possible human carcinogen based solely on inhalation studies. CH3 H 3 C—O — C —CH 3 CH3 Methyl ferf-butyl ether
The Administration wants Congress to replace the Clean Air Act's oxygenate requirement with a standard for renewable fuel content in all gasoline. Agriculture Secretary Dan Glickman explains that a renewable fuel standard could also boost farm income by increasing sales of ethanol, a compound made primarilyfromcorn arid used as a gasoline oxygenate. The plan would have "negligible" im6
MARCH 27,2000 C&EN
pact on gasoline prices, says Environmental Protection Agency Administrator Carol M. Browner. She says changes to the Clean Air Act should also include provisions to preserve cleaner air achieved through the use of MTBE. Many legislators from the Corn Belt
endorse the Administration's plan. Senate Minority Leader Tom Daschle (DS.D.) says the plan "is great news for farmers, clean air, clean water, and efforts to reduce our dependence on foreign oil." While many Republicans and the American Petroleum Institute (API) support phaseout of MTBE, they reject the idea of a renewable fuel standard. The oil industry trade group says a renewable fuel standard would increase the cost of gasoline "and is completely unnecessary to improving air quality." The 1990 amendments to the Clean Air Act required reformulation of gasoline by addition of oxygenates, such as MTBE, to cut vehicle emissions. The clean air law specifies that only reformulated gasoline may be sold in a dozen urban areas with smog problems. In addition, a number of states and cities have voluntarily chosen to use reformulated gasoline. About 87% of reformulated gasoline uses MTBE as an oxygenate. That puts annual use of MTBE at about 4.5 billion gal, according to EPA.
Refiners have used small amounts of MTBE as an octane booster since tetraethyl lead additives were phased out in the 1970s. But drinking water contamination did not become a nationwide concern until after the 1990 Clean Air Act oxygenate requirements led refiners to double or triple the amount of MTBE blended into gasoline. Because MTBE is highly soluble in water, it tends to migrate more quickly into groundwater than other components of gasoline. The U.S. Geological Survey has detected MTBE in about 20% of the groundwater in areas that use reformulated gasoline compared to about 2% of the groundwater in areas that do not use the reformulated fuel. In February, the oil industry joined with the American Lung Association, the Natural Resources Defense Council, and several northeastern states in calling for Congress to repeal the Clean Air Act oxygenate mandate to protect drinking water supplies (C&EN, Feb. 7, page 36). Browner says the best way to address MTBE is for Congress to amend the Clean Air Act. But as a "backstop measure," EPA has begun a regulatory action under the Toxic Substances Control Act to ban use of MTBE in gasoline, a process that may take three years, she says. That process has been used successfully only seven or eight times in the 23 years since the statute was enacted. And API doubts that EPA can make a strong case in this instance. Sen. James M. Inhofe (R-Okla.), chairman of the Senate Environment & Public Works Committee's Subcommittee on Clean Air, criticized the EPA regulatory effort, saying a rule would take too long to implement and would be vulnerable to litigation. "The last time this . . . authority was used was on asbestos in the late '80s, and that was overturned by the courts in 1991," Inhofe notes. Congressional action to drop the MTBE requirement from the Clean Air Act is possible this year. However, the addition of an ethanol requirement is problematic at best because of Republican opposition in the House and Senate. The proposal does have an election-year spin. As Browner says, if the plan "happens to be good for Al Gore, too, that's great." Cheryl Hogue
