MTBE (Methy tertiary-butyl ether)

In 1979 MTBE was developed as a fuel oxygenate to replace lead. Added to gasoline, MTBE succeeded in increasing octane ratings and decreasing air pollution. Unfortunately, in the process it contaminated groundwater in 49 states and is now threatening to become what one popular television news magazine calls, the biggest environmental crisis of the next decade.

The presence of MTBE has been detected in shallow groundwaters and surface waters throughout the United States. Due to its high solubility, low adsorption to soil and aquifer material, and poor natural biodegradation relative to other hydrocarbons, MTBE is highly mobile and persistent. Leaks from underground storage tanks (USTs) and pipelines are responsible for most of the groundwater contamination. Surface waters are more likely being contaminated by nonpoint sources, such as recreational watercraft.

The US Environmental Protection Agency (EPA) has classified MTBE as a possible human carcinogen based on inhalation studies and is currently researching the health effects of MTBE exposure. An EPA drinking water advisory has been issued to water suppliers to keep MTBE levels in the range of 20 to 40 ppb or lower to prevent taste and odor problems and to protect against potential health effects. The EPA has also included MTBE on a list of contaminants that may require regulation based on their known or anticipated occurrence in public drinking water systems.

MTBE has a turpentine-like odor that can be detected at very low concentrations (2.5 ppb). When water containing trace levels of MTBE is heated for use in cooking or showering the contaminant tends to aerate, making its odor even more noticeable.

Taking advantage of a burst of publicity inspired by a CBS “60 Minutes” story in January 2000 and a class-action lawsuit filed in New York, water industry groups are calling for swift action to prevent and clean up pollution caused by the fuel additive methyl tertiary-butyl ether (MTBE). The Sacramento-based Groundwater Resources Association (GRA) has called for an immediate ban on the chemical in California.

The trade group cited costs for clean up and treatment by water utilities it estimates could top $1 billion. The Water Quality Association (WQA) in Lisle, IL, is helping member dealers educate concerned consumers about possible removal solutions. “MTBE contamination presents a real and growing threat to the quality of our drinking water resources and public health,” said Jack Hoffbuhr, executive director of the American Water Works Association (AWWA). “The large cleanup costs and possible health risks associated with MTBE contamination demand immediate focus on ways to prevent it.”

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