MTBE - Gas Cleanup
MTBE stands for Methyl Tertiary-Butyl Ether and is a gasoline additive that has contaminated drinking water across the country. Made from methanol and a by-product of the oil refining process, it was added to gasoline in an attempt to make gas burn cleaner, but studies show it has had little effect on curbing air pollution.
MTBE, like other ethers, is hydrophilic; in other words, it has a chemical attraction to water molecules. It is more than thirty times more soluble in water than other toxic compounds of gasoline. MTBE does not readily bind to soil particles and resists natural degradation. It is these qualities that cause MTBE to travel easily and quickly into underground water supplies. When MTBE is released into the environment via transport accidents, leaking tanks or by simply over filling at gas stations, MTBE travels great distances underground to the water table. MTBE can contaminate surface waters, but underground drinking water supplies are most at risk.
In a major setback to the oil and chemical industries, on July 27, 1999 an EPA panel recommended that MTBE be reduced in use as a gasoline additive because of toxic hazards that MTBE poses to drinking water supplies throughout the country. MTBE is a known animal carcinogen and possible human carcinogen. The reported U.S. production of MTBE in 1992 exceeded nine billion pounds - virtually all of it is added to gasoline. Oil companies reportedly make approximately $3 billion per year from MTBE.
Where Did MTBE Come From?
In the late 1970's, gasoline companies started using MTBE in gasoline to replace lead and to boost octane. In 1990, in response to concerns over air pollution and aggressive industry lobbying, Congress amended the Clean Air Act to require the use of fuels which add oxygen to gasoline. It is the best known oxygenate, and the one embraced by most oil companies although other oxygenates are used in some areas.
Some Concerns
MTBE easily reaches and contaminates groundwater because it is water-soluble and degrades very slowly. It spreads quickly and persists indefinitely in groundwater. This water solubility makes it difficult and costly to clean up. For example, a simple car accident could contaminate an entire underground aquafier.