The summary states, "The PHG is based on carcinogenic effects observed in experimental animals." They then go on to cite the findings of six studies conducted in 1992, 1995, 1997 and 1998, in which rats and mice, force fed and forced to breathe air containing MTBE, developed significant increases in tumors of the testes and liver, lymphoma, leukemia, and kidney tubules. Some animals developed cancers at multiple sites. The paper goes on to state, "We reviewed these studies and the reported criticisms carefully, and found the studies are consistent with other MTBE findings, and are of similar quality to studies on many other carcinogens... The results of all available studies indicate that MTBE is an animal carcinogen in two species, both sexes, and at multiple sites, and five of the six studies were positive."
In February of 1996, the Office of Science and Technology Policy released a report through the White House National Science and Technology Council (NSTC). Significantly, this report was peer reviewed by the National Academy of Sciences under guidance from the National Research Council (NRC). The report focused primarily on inhalation exposure to MTBE. A final report was released in 1997. The bottom line? The limited review in the NRC report concluded that the evidence supported MTBE as an animal carcinogen. The NSTC findings concluded, "...there is sufficient evidence that MTBE is an animal carcinogen...the weight of evidence supports regarding MTBE as having a carcinogenic hazard potential for humans."
In 1997, the EPA issued a "Drinking Water Advisory: Consumer Acceptability Advice and Health Effects Analysis on Methyl Tertiary-Butyl Ether (MtBE)" (www.epa.gov/OST/tools/MtBEaa.pdf)
They recommend that no more than 20-40 μg/L (20-40 ppb) of MTBE would assure aesthetic acceptability-the taste and odor threshold. Because this level of contamination is much lower than levels that produced health effects seen in rodent studies up to that point, they reasoned, it would also protect consumers from potential health effects. EPA advisories, by the way are simply "guidance to communities" and "are not mandatory standards for action...and are not legally enforceable." For the sake of comparison of levels, in the city of Glennville, California, one well contained 20,000 ppb or one thousand times the EPA Advisory level!
It is now about 6 months since the release of the EPA Blue Ribbon Panel Report on Oxygenates in Gasoline, and Congress has not moved to remove the oxygenate requirement or to aid states and communities in removing MTBE from their drinking water. Throughout this period et continuing regulatory inaction, MTBE is showing up in varying degrees nearly everywhere it is tested for, yet there is no federal requirement that MTBE even be tested for in the nation's drinking water.
In the meantime, individual states are moving ahead on their own to establish guidelines, standards or action levels. So far, they range from 10 ppb (Maryland) to 240 ppb (Michigan). Most are in the 20-70 ppb range. For a list of those states that have established these MTBE guidelines to date, and whether they are based on aesthetics or health concerns, go to the MTBE story on The Ark Institute's web site at http://www.arkinstitute.com
Is MTBE in Your Water?
Do you know if your municipal water supply is contaminated with MTBE? Is your supplier even testing for it? If you don't know, call your municipal water supplier and ask. Your state's environmental protection agency is another resource for this information. Have any of your state's major aquifers or lakes been tested? If you are on a well close to a populated area with gas stations, have you had your own well tested? Have ether wells in your area been tested? If you find your water supply has MTBE it, can you determine the source? What can you or your community do about MTBE contamination?
Unfortunately, the chemical properties of MTBE make it very difficult to clean up. It moves further and faster through coil and is more water soluble than ether gasoline components. It does not adhere well to soil particles. It does not break down easily. What's more, it vaporizes into the air at 55.2 degrees Celsius or about 131 degrees F. When you consider that the average home hot water heater is set at 140 degrees F or higher, you can see that running hot water for a bath or hot shower, cooking, or using a washer or dishwasher can vaporize MTBE from the water, making it part of the air in our homes. This makes it available for inhalation as well as for drinking from cold water, and the simple fact is, no one yet knows the effects of inhalation or ingestion of MTBE in any quantity on adult humans, let alone young children and the human fetus.
