MTBE found throughout the American Midwest

The petrol additive MTBE, which has been found to rapidly pollute water supplies, has been found in a majority of petrol sold throughout the Midwestern States even though it is seldom used in the region.

Researchers from Purdue University North Central in Westville, Indiana, found MTBE (methyl tertiary butyl ether) in more than 70% of petrol samples from more than 200 sites in Indiana, Illinois and Michigan, even though ethanol is the main oxygenate for reducing air pollution in these states. “MTBE is not supposed to be there,” said the study’s lead investigator, Reynaldo D. Barreto, who warned that the unexpectedly widespread presence of the chemical suggests there is a “ticking time bomb” that could adversely affect drinking water. These results come less than one week after an investigation of Californian state records showed that MTBE has already reached 48 wells in public water systems statewide serving hundreds of thousands of people (see related story). However unlike in California, the three Midwestern states have never made extensive use of the additive.

In Indiana, 70% of petrol samples obtained from 156 service stations from throughout the state, which uses ethanol as the major reformulating agent, were contaminated with MTBE, especially in southern parts of the state, near to areas where MTBE has been used in adjoining border states. The chemical can travel up to three miles from its point of origin.

Although data from Illinois and Michigan are not yet complete, petrol samples surveyed in these areas also indicate widespread MTBE contamination, according to Barreto. This was unexpected, given that ethanol is the predominant reformulating agent in Illinois and that no reformulated petrol is used in Michigan, the researcher says. Barreto believes that the presence of MTBE in the transportation and storage tanks long after its use calls for a ban on use of the chemical as a fuel additive to prevent it from spreading as changing the transportation and storage infrastructure to reduce its threat would be prohibitively expensive.

MTBE has been used in increasing amounts since 1995, when amendments to the Clean Air Act mandated the use of reformulated petrol in heavily polluted areas. By law, reformulated gasoline must contain oxygenates designed to reduce smog-causing emissions, of which the two most widely used are MTBE, derived from natural gas, and ethanol, generally made from corn. However, MTBE has come under intense scrutiny after numerous studies showed it can leak from underground storage tanks and other sources to contaminate the drinking water supply. Although its toxicity to humans is unclear, the oxygenate can make water undrinkable due to its foul smell and bad taste.

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