MTBE is the shorthand abbreviation for methyl tertiary-butyl ether, a volatile organic compound that belongs to a category known as oxygenates. Oxygenates are added to fuel to increase its oxygen content. MTBE has replaced the use of lead as an octane enhancer in gasoline throughout the United States since 1979. MTBE reduces carbon monoxide and ozone levels caused by auto emissions. From 2000 to the present, at least twenty states have enacted legislation limiting or banning the use of MTBE.
With these air quality benefits, you may wonder why there is concern about the use of MTBE. A growing number of studies have detected MTBE in ground water throughout the country; in some instances, these contaminated waters are sources of drinking water. Even very low levels of MTBE can make drinking water supplies undrinkable, due to its offensive taste and odor.
MTBE can leak into the environment, and potentially into drinking water sources: 1) wherever gasoline is stored and 2) whenever it is spilled during transport. Leaks can occur in underground and above ground storage tanks. Spills are possible during accidents with pipelines, trucks, ships and automobiles–anytime a fuel tank is damaged. Contamination can also occur from careless disposal by consumers of “old” gasoline, as well as from emissions of marine engines into lakes and reservoirs.
Because MTBE dissolves easily in water and does not “cling” to soil very well, it migrates faster and farther in the ground than other gasoline components. That makes contamination of public drinking water systems and private wells far more likely. The chemical structure of MTBE does not break down quickly, so it is difficult to remove from ground water. Hundreds of communities across the U.S. face many millions of dollars in costs either to clean up MTBE contamination or to find replacement water supplies.
How is MTBE harmful to human health?
The majority of the human health-related research conducted to date on MTBE has focused on effects associated with the inhalation of the chemical. When research animals inhaled high concentrations of MTBE, some developed cancers or experienced other adverse health effects. To date, independent expert review groups who have assessed MTBE inhalation health risks have not conclusively determined if it is a significant health threat. Researchers also have limited data about what the health effects may be if a person swallows MTBE. The Environmental Protection Agency still does not consider the available data to be adequate to estimate potential health risks of MTBE at low exposure levels in drinking water. The data does support the conclusion, however, that MTBE is a potential human carcinogen at high doses. Some studies have suggested that exposure to high levels of MTBE causes tumors of the liver, kidneys, testicles, and some other organs. These same studies have shown damage to fetal development, as well as effects on the nervous system ranging from hyperactivity to seizures and unconsciousness.
What should I do if I suspect MTBE in my drinking water?
It is possible your water would taste and/or smell like turpentine if MTBE is present at levels around 20-40 parts per billion (ppb), or at even lower levels. To confirm the presence of MTBE in your water, you can purchase a home testing kit and then submit your drinking water samples to a professionally certified lab for evaluation. If your drinking water is supplied by a public water system, you can also contact the municipal authority directly to ask whether they monitor for MTBE and what levels, if any, have been detected.
Reverse osmosis with activated carbon pre-filtration will reduce MTBE from drinking water, as well as many other contaminants risks like nitrate and chromium. Another effective method for filtering out MTBE contamination are the specially designed filters for an under sink system, like 250A cartridges by Pentek or Culligan.