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California and the West

Study Urges Phasing Out Gas Additive

Environment: MTBE has dubious value in reducing air pollution and has tainted ground water, researchers say.


MTBE, the controversial gasoline additive that has contaminated ground water throughout the state, does little if anything to clean the air and should be phased out within six years, University of California researchers have concluded.

The study, commissioned 10 months ago by the Legislature and governor's office, was designed to help California officials decide whether to ban the oxygenate, which refineries add to fuel to boost octane and decrease carbon monoxide emissions.

A team of researchers from four UC campuses said gasoline manufacturers are capable of meeting California's strict air quality standards for cleaner burning fuel without the chemical. The report states that MTBE endangers the state's drinking water and could worsen water shortages during drought years. It recommends that MTBE be phased out over a period of three to six years.

"It is clear that we are placing our limited water resources at risk by using MTBE," the report states. The researchers said the cost of treating the contaminated water "could be enormous," possibly exceeding $1 billion a year.

In much of California, however, federal law stands in the way of eliminating MTBE. The Clean Air Act requires gasoline in the Los Angeles Basin, San Diego and Ventura counties and Sacramento--all classified as severe or extreme areas for air pollution--to contain oxygenates.

In much of Northern California, where air is cleaner, Chevron Corp. and Tosco Corp. are already producing MTBE-free gasoline because of well-publicized concerns over polluted water wells.

Sen. Dianne Feinstein (D-Calif.) and Rep. Brian Bilbray (R-San Diego) have introduced legislation that keeps California's pollution standards but eliminates the federal requirement for oxygenates.

"This report backs up my strong belief that MTBE is not necessary and pollutes drinking water," Feinstein said.

Led by experts from UC Davis, the researchers recommend that the phaseout take place gradually so that refineries have time to retool their massive operations and change their formulas without triggering fuel shortages or driving up the price of gasoline in California.

Officials have been surprised over the past couple of years to discover how rapidly MTBE, or methyl tertiary butyl ether, has moved through underground water basins as it leaks from faulty underground fuel tanks.

Santa Monica, South Lake Tahoe, Sacramento and Santa Clara are among the areas that have shut down wells found to contain the chemical. The effects of MTBE on human health are poorly understood, but it appears to cause cancer and birth defects in laboratory animals.

The dispute over MTBE has been portrayed as one that pits clean air against clean water.

California oil refineries spent several billion dollars revamping their massive facilities to begin producing cleaner-burning gasoline, which has been required in California since 1996. In the reformulation, the refineries add MTBE to gasoline as an octane booster and to enhance combustion.

Reformulated gasoline remains critical to anti-smog efforts because it has removed emissions equivalent to 3 million cars. But the UC researchers say MTBE is not a necessary ingredient in the cleaner-burning formulas; ethanol can work as well, as can nonoxygenated formulas.

"MTBE and other oxygenates were found to have no significant effect on exhaust emissions from advanced technology vehicles. . . . Thus there is no significant additional air quality benefit to the use of oxygenates such as MTBE in reformulated gasoline," the report states.

Officials from the Air Resources Board, which set the fuel standards, agree. As long as gasoline meets the state's emission standards, they do not care if it contains MTBE or other oxygenates.

Oil companies support the legislation to end the requirement for oxygenates, saying it gives them more flexibility. But they say if MTBE is banned, they agree with the UC team that the change should not be immediate because it could disrupt gasoline supplies and prices.

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