The MTBE controversy

Controversy over the gasoline additive methyl tertiary butyl ether (MTBE) tests the quality of environmental debate in the U.S.

The substance has shown up in ground water, including some used for drinking. So far, the U.S. Environmental Protection Agency has resisted environmentalist pressures for a ban. It instead seeks answers to questions that now lack clear answers: What is the nature of the threat? How serious is the risk to human health? What environmental and economic tradeoffs may be involved?

To this list refiners might usefully add: How much flexibility should they have to pursue environmental goals?

Oxygen mandates

Refiners add MTBE to gasoline to boost octane and meet federal requirements for oxygen content. Although they have other options for meeting oxygen mandates, such as ethyl tertiary butyl ether and ethanol, they favor MTBE for economic reasons.

But MTBE is soluble, moves into ground water quickly, and biodegrades slowly. In concentrations exceeding Environmental Protection Agency advisory levels for odor and taste, it has contaminated drinking water in a few places. In a number of other locations, it has been found in drinking water at much lower levels. And its occurrence in ground water not used for drinking is apparently even more widespread, although concentrations are usually low.

A year ago, EPA issued an advisory setting the concentration guidelines for odor and taste at a range well below levels that might raise health risks. It also has increased ground-water monitoring and pushed regulation of underground storage tanks. More recently, it formed an advisory committee to study health issues raised by oxygenates in gasoline (OGJ, Dec. 7, 1998, p. 48).

EPA thus seems determined to deal with the issue mainly as a problem related to underground storage tanks but to study the possible risks to human health. The approach is proper and heedful of tradeoffs. The agency notes that MTBE displaces substances more certainly dangerous and occurs in gasoline under programs that have cut air pollution. Why give up a dollar's worth of environmental benefit for a dime's worth or less?

When unwanted chemicals enter drinking water, however, fear tends to override science. If fear gives way to panic, EPA will feel pressure to impose a ban no matter what its studies determine about health risks. Indeed, some of the environmental groups permanently camped in EPA's hallways incite panic as way of doing business. And the growing public outcry against MTBE is hardly unwelcome to producers of competing oxygenates.

The controversy thus tests EPA's ability to deal scientifically with an environmentally celebrated worry that, except in a very few cases, doesn't look like a serious problem.

The agency also may find itself in a cross-fire in the refining industry. Companies with lots of MTBE capacity would be hurt not only by an MTBE ban but also by any relaxation of gasoline oxygen specifications. Yet discussion has emerged over just such a change.

Federal legislation last year proposed that in California, where concern about MTBE in drinking water is intense, oxygen not be required in reformulated gasoline (RFG) otherwise meeting the state's rigorous standards for environmental performance. It enlivened an old question: Why-except to guarantee a market for oxygenates-does RFG need a specification for oxygen? There has never been a clear answer. Many refiners probably would add oxygen to gasoline without a mandate. Requiring it at set concentrations, however, limits flexibility for no good reason.

Familiar mix

The MTBE issue thus involves a familiar mix of fear, conflict, and complexity-the raw materials of environmental politics. Science and reason will either control the process or boil off in the controversy. EPA seems to want to keep them involved. Refiners, whatever their stake in MTBE, should want the same thing.