The second most frequently detected volatile organic chemical in groundwater, MTBE, has been found from coast-to-coast. In 1991, EPA approved MTBE as an air-cleaning gas additive against high smog and carbon monoxide in dense urban areas. Today, MTBE is a suspected chemical carcinogen, which the U.S. Geological Survey has found in more than a quarter of the nation's shallow urban wells and in streams, lakes, rain and snow, and even in remote rural areas.

The Association of California Water Agencies reports that California and about a third of the rest of the country now use gasoline with high levels of MTBE; the rest use gas with low levels of the chemical. Even if MTBE were banned today, years would be required to remove it from the nation's water, and the cost could run into billions of dollars.

Although the EPA classifies MTBE as a possible human carcinogen because laboratory rats and mice that breathe or drink it have developed lymphoma, leukemia, testicular tumors, thyroid tumors, and kidney tumors, so far, the EPA has resisted calls to ban MTBE. One of the subtleties of the MTBE scare in tap water across America is that MTBE is considered a fast-leaching compound. The U.S. Geological Survey reported that MTBE doesn't biodegrade; it can affect water supplies for years.

MTBE FACTS
by Katrie DiTella

You may have noticed recently that Methyl tertiary-butyl ether (MTBE) is a hot issue in the water quality world. This spring the Water Quality Extension Program will have a series of fact sheets available which address MTBE. In the meantime, below you will find answers to some common questions related to MTBE.

What is MTBE?

MTBE is produced by the chemical reaction of methanol and isobutylene, and it does not occur naturally. MTBE is a volatile organic compound in the form of a flammable, colorless liquid. Since the 1970s, MTBE has been added to gasoline. Originally, it was used in low concentrations (about 2-3%) to raise the octane of gasoline. Now, MTBE is used to raise the oxygen content of gasoline and its concentration in gasoline is higher (generally from 11-15%). Gasoline reformulated with MTBE promotes more complete combustion and reduces vehicular emissions of carbon monoxide, ozone, and air pollutants such as benzene.

The Clean Air Act Amendments of 1990 (CAA) required the Environmental Protection Agency to issue regulations which would reformulate gasoline in areas with unhealthy levels of ozone-forming and toxic air pollutants. MTBE fulfills the CAA's oxygenate requirements. Reformulated gasoline has been used in New York as well as several other states. The New York State Department of Environmental Conservation has detected MTBE in groundwater in every New York County.

What happens to MTBE in the environment?

MTBE evaporates when exposed to air. It dissolves when mixed with water. Contamination of drinking water with MTBE most likely develops from gasoline spills. Such spills may be large, like those from a leaking underground or above-ground gasoline storage tank. Spills may also be small, such as those which can occur while refueling, discarding old gasoline improperly, or leaking gasoline from vehicles. Because MTBE does not bind well with soil and is most likely not stored by plants, it can move through the ground and into groundwater quickly. MTBE has been found to move through water supplies faster than other gas ingredients such as toluene, xylene, etc.

Is MTBE in Drinking Water harmful?

The potential for effects of MTBE on human health depend on how much MTBE is present in the water and the length and frequency of exposure. MTBE is a potential human carcinogen. No studies have yet been completed to determine if MTBE causes cancer in humans, however, tests on rats have shown that MTBE can cause cancer in animals. Other effects of exposure to (or ingestion/inhalation of) MTBE include the following: headaches, eye irritation, nose and throat irritation, cough, nausea, dizziness and disorientation.

MTBE has a very unpleasant taste and odor and these properties can make contaminated drinking water unacceptable to the public. However, humans vary widely in the concentrations they are able to detect.

How can I get my water tested?

You should have your water tested annually regardless of whether or not you think your water may be contaminated with any pollutant(s). If you have a private well and are concerned about MTBE in your drinking water, contact your county or regional Department of Health for a list of local laboratories which test water for MTBE. Ensure that the analysis be performed by a laboratory certified to perform EPA certified methods (EPA Method 524.2 should be followed; gas chromatography/mass spectrometry). Prices vary but the test should cost approximately $150. You may want to consider testing your water if you have experienced a change in taste or odor or if you suspect a gasoline spill in close proximity to your well.

How can I get rid of MTBE if it is in my water?