Methyl Tertiary Butyl Ether (MTBE)
MTBE (methyl-t-butyl ether) is a member of a group of chemicals commonly known as fuel oxygenates. Oxygenates are added to fuel to increase its oxygen content. MTBE is used in gasoline throughout the United States to reduce carbon monoxide and ozone levels caused by auto emissions. MTBE replaces the use of lead as an octane enhancer since 1979.
Potential sources of MTBE are leaks from underground storage tanks; discharge of unburned fuel from water craft (especially 2-stroke engines); gasoline spills from automobile and tanker truck accidents; gasoline spills and drips when refueling automobiles, lawnmowers, tractors and other machines; plus leaks from pipelines and aboveground storage tanks.
As the EPA recognizes, there is still much uncertainty about the extent of the health risk associated with chronic, low-level exposure to MTBE in drinking water. MTBE is a known animal carcinogen. The U.S. Environmental Protection Agency classifies it as a possible human carcinogen. At concentrations at or below five (5) parts per billions ("ppb"), MTBE gives otherwise pure water a foul turpentine-like taste and odor, rendering it unfit for consumption. The distressing taste and odor can be detected in water in concentrations at or below 5 parts per billion, although sensitivity to the odor and taste varies greatly among individuals.