While MTBE has been successful in reducing air polluting emissions from vehicles, the controversial chemical has been found in groundwater sources far from the 17 states which now require its use, said Charlie Voinche, vice president of Petroleum Laboratories of Lafayette, La. and Houston, Texas.
"MTBE is highly water-soluble and it can travel from watershed to watershed," said Voinche "It can migrate quickly through soil and it is resistant to breakdown in soil when compared to gasoline."
"Use of reformulated gasoline containing MTBE was required in Denver, Colo. and a few years later US Geological Survey (USGS) researchers found it in a low-level aquifer near Reno, Nev., hundreds of miles from Denver and in an area where use of reformulated gasoline was not required," Voinche added.
MTBE is used to reduce carbon monoxide and ozone levels caused by automobile emissions. MTBE has replaced lead as an octane enhancer in gasoline since 1979 and it helps increase the oxygen content of fuel. Gasoline reformulated to reduce emissions contains about 12 percent MTBE, Voinche said.
"There is no question use of MTBE has had an effect on air quality. The question is what is it doing to our water? The history of MTBE may be similar to the history of things such as asbestos, that we thought were beneficial at the outset, but turned out not to be," he said.
Speaking to Louisiana Ground Water Association members, Voinche said MTBE is a concern in Louisiana because it is manufactured in large quantities by area refineries and is transported through the state in pipelines and on barges and tanker trucks and is stored there in surface and underground tanks.
Noting the amount of MTBE produced in the 1990s in the US ranked second among all organic chemicals, Voinche said he believes information about the chemical gathered to date represents only 'the tip of the iceberg' regarding its effects.
"In shallow groundwater samples taken in urban areas of the United States, 27 percent show MTBE to be present," he said. "All the data on MTBE is not in and we don't know the magnitude of the problem we may have 10 years down the road. Time will tell."
The researcher said the presence of MTBE in an aquifer also indicates likelihood of future contamination by other petroleum-related substances which could also seep through surrounding soil.
"MTBE is one of the first substances which filters into aquifers. MTBE detection can help with early detection of contaminated areas because when you see MTBE in the soil or groundwater, other hydrocarbon components will follow," he said.
Voinche said MTBE concentrations as great as 2,700 parts per billion have been found in some aquifers. The Environmental Protection Agency (EPA) is considering limiting permissible MTBE levels from 5 to 40 parts per billion for uses other than drinking water and 5 to 20 parts per billion for drinking water. EPA also is requiring all large drinking water systems and a representative sample of smaller systems to monitor and report presence of MTBE in their systems.
The federal agency has recommended banning or phasing out MTBE in gasoline and substituting other additives, but Voinche said President George W. Bush, the EPA director, or Congress may offer different approaches for handling the problem.
"It's going to be a health issue and the question is what MTBE rate the EPA will say is good and what they will say is bad," he said.
Voinche said MTBE's presence in water can be detected through gas chromatography and the two most promising means of removing it from groundwater are reverse osmosis and carbon filtration. Microbe technology can be used to remediate soil contaminated by MTBE, but the researcher said the microbes couldn't remove MTBE from water.
"They can get it out of the groundwater, but the economics are not feasible for most municipalities. They can't do it at a cost rate acceptable to the citizens," Voinche said.
He said costs of laboratory testing water samples for MTBE range from $60 to $130 each, new field testing kits are being developed, but they are not as accurate as laboratory tests.
Voinche said if any positives surround current concerns regarding MTBE, they could be in encouraging development of alternative fuels or additives to replace MTBE.
He said well drillers also could benefit from the ongoing discussions about MTBE because "water is going to be so precious that clean water will have a big dollar value placed on it, so that could be a positive for your industry."
Noting the potential costs of MTBE testing and clean-up efforts and possible health threats from the substance, Voinche said those issues raise a key question. "Since Congress mandated the use of reformulated gasolines containing MTBE, who should be held liable for damages and health and clean-up issues?" he asked.