MTBE: Concern or Crisis for U.S. Drinking Water

MTBE: Concern or Crisis for U.S. Drinking Water?

March 13, 2000

MTBE (methyl tertiary butyl ether) is contaminating drinking water, lakes, and aquifers throughout the U.S. In this article I will provide some background on the history of this chemical with links to
original documents. It is my hope that this information will help you assess what potential impact it may have on you and your family, today, and in the future, and what technologies are currently
available to treat contaminated water on the community and home levels.

Though local or regional water contamination events from accidental sewage and chemical or oil spills have received national news coverage from time to time, none of these accidents has anywhere near the breadth and depth of potential impact on the nation as MTBE does. Until CBS's 60 Minutes journalist, Steve Kroff, said on national television on January 16, 2000, "Even the government now says that we're facing a national crisis if something isn't done to stop MTBE from leaking into our drinking water," there was little national concern. This is changing, but first, some history.

Since the late 1970s, MTBE was used in low concentrations in premium gasoline to increase octane ratings. In 1990, The Federal Reformulated Gasoline Program was created as part of the Clean Air Act Amendments and implemented in 1995. Congress mandated the use of reformulated gasoline (RFG), that is, gasoline mixed with other chemicals, to attain 2 percent oxygen by weight in those areas of the country with the worst ozone and smog problems. The Act requires "wintertime oxyfuel" to contain 2.7 percent oxygen by weight. In winter, most metropolitan areas can use ethanol to meet oxygenation needs, as volatility of ethanol is not as much of an issue in cold weather, but MTBE is the oxygenate of choice in over 85 percent, and ethanol in 8 percent, of all reformulated gasoline today. (You may want to read the final report of the Environmental Protection Agency's Blue Ribbon Panel on Oxygenates in Gasoline, "Achieving Clean Air and Clean Water.")

As of March, 1999, gasoline reformulated with MTBE has been used in nineteen states and Thirty-two regions of the U.S. to meet Federal clean air standards. The Federal government does not specify which oxygenate must be used, but only that clean air standards be met. According to industry data through the fall of 1999, MTBE is used at the rate of about one gallon of pure MTBE for every ten gallons of reformulated gasoline used in the U.S., or 10 percent of every tank. In California it is closer to 11 percent. On a more personal level, if your region is using this oxygenate, every time you fill up at your local gas station, you'll get about nine gallons of gasoline and one of MTBE for every ten gallons you buy. Remember, that's every time you fill up. Now multiply that times the numbers of gallons of gas used in this country every day, by every person who fills his/her tank with gasoline and you'll likely find the magnitude of this consumption difficult to conceptualize.

According to the State of California's March 1999 paper, "Public Health Goal For Methyl Tertiary Butyl Ether (MTBE) in Drinking Water," MTBE was the eighteenth most produced chemical in the U.S. in 1994. In 1995, it was twelfth, and in 1997, MTBE was the second most produced chemical in the country! Californians use more than 13.7 billion gallons of gasoline a year, not counting diesel fuel. At 11 percent MTBE in California's gasoline mix, that's 1.5 billion gallons of pure MTBE bought, trucked over highways, stored in underground tanks, sold, and finally burned in vehicles in California alone each year! Nationally, it's about 4.5 billion gallons a year.

Now, the good news about the widespread use of MTBE is that it does what oxygenates are supposed to do. It boosts octane, improves combustion efficiency, and promotes the more complete burning of gasoline. It has significantly reduced the levels of carbon monoxide and ozone released as gasoline combustion by-products. There is no doubt about it; reformulated gasoline has decreased—often more than expected—dangerous pollutants in our cities, but what is really tough about the MTBE contamination issue is that this chemical also has a dark side.

The Dark Side of MTBE

The first known impact of MTBE on our nation's water supply was in 1980 when a municipal water well in New Jersey was found contaminated with 96 ppb (parts per billion) of MTBE. Then, in 1996, the city of Santa Monica, California, discovered that 70 percent of its municipal wells were contaminated with it. They didn't even know what MTBE was when they found it. It wasn't on state or federal government's lists of potential water contaminants, but when they drew a circle containing these municipal wells on their city map, they discovered, within that circle, twenty gas stations with documented underground gas tank leaks. Soon the water began to smell of turpentine, the way most people describe the smell of water contaminated with MTBE. How much MTBE does it take to foul the smell of water? According to the 60-Minutes interview with Santa Monica water officials, a single cupful of MTBE in a 5 million gallon reservoir is sufficient to render the water undrinkable. The city had no choice but to scramble to close the majority of its wells and buy expensive Colorado River water at a cost of about $3 million a year.

Since Santa Monica closed its wells, the state of California has identified 10,000 MTBE-contaminated groundwater sites. What’s more, forty-nine states have found it in groundwater, and twenty-one of these have had to shut down at least one of their wells due to MTBE. As of this writing, it has been found in sixty-five public drinking water supplies in New Jersey, in one hundred public water supplies in Long Island, New York where it has leaked from over four hundred gasoline storage tanks. It has been found in Maine, Albuquerque, Denver, Dallas, Atlanta, Hartford, Las Vegas and it has virtually shut down the tiny town of Glenville, nestled at the foothills of the Sierra Nevada Mountains in California. In each case, in forty-nine states, MTBE enters groundwater from leaking, underground gas tanks, from gas spills, and/or from recreational water craft on lakes and rivers.

In 1997, MTBE was discovered in Lake Tahoe in California. South Lake Tahoe was forced to shut twelve wells—a third of its water supply. The city is suing twelve local gas stations, twelve major oil companies and several producers of MTBE hoping to have them share in the enormous costs of removing it from their drinking water. An attorney representing the city, Mr. Victor Sher, told 60-Minutes that we are seeing just the tip of the MTBE iceberg because it is used throughout much of the country and everywhere it is used it gets into the environment.

The Environmental Protection Agency (EPA) has known about leaking underground gas tanks and the subsequent contamination of wells, rivers, bays, etc., for many years. In fact, according to Bob Perciasepe, an assistant administrator at the agency, the EPA ordered underground gasoline storage tanks replaced or upgraded by 1998, but over 400,000 tanks are not covered by the order and many of the new tanks are already leaking! It would seem, from a 1987 EPA memo written well before the Clean Air Act of 1990 mandating reformulated gasoline, that this potential national crisis could have been prevented thirteen years ago. The memo states:

Known cases of drinking water contamination have been reported in four states, affecting 20,000 people. It’s possible that this problem could rapidly mushroom due to leaking underground storage tanks. The problem of groundwater contamination will increase as the proportion of MTBE in gasoline increases.

EPA’s Perciasepe told 60-Minutes, “Any optimism anybody had that we could manage this potential problem has not come to fruition, and before this becomes a national crisis, before this gets worse, we need to change the way we make clean-burning gasoline.” Despite the warning sounded by that memo, the Clean Air Act of 1990 was passed three years later without studying the possible effects of drinking MTBE-contaminated water. Now thirteen years have passed, and there have still been no EPA or other federally-sponsored studies on the effects of MTBE on humans. EPA’s Perciasepe confirmed that he was not aware of any study done on the health effects of MTBE in drinking water. He must not be aware of the ongoing studies done at the University of California, nor of those done in Italy five years ago. The Italian study showed that MTBE in high doses caused three cancers in laboratory animals: lymphoma, leukemia, and testicular cancer. California’s MTBE website features a paper entitled, “Public Health Goal for Methyl Tertiary Butyl Ether (MTBE) in Drinking Water” in which they adopt 13 µg/L or 13 ppb as the state’s public health goal or PHG.

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). 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 six 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 of 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 website.)

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 other 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 soil and is more water soluble than other 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. There is no practical technology yet available for removing MTBE from household air. Removing it from household water before it is vaporized would appear the only solution to MTBE vapor generated in the home. The odor of turpentine when taking a shower or boiling water has been reported in contaminated water areas.

There are a few technologies that can remove much of MTBE from water, but many of them are experimental, far too costly to be practical, or require water to be heated before putting through treatment. Time-tested, activated carbon for the removal of organic compounds is already part of most home filtering devices, but MTBE has proven difficult to remove by standard activated carbon filters. Others, compressed carbon blocks, require pressure to drive the water through the block. Under pressure, the greater portion of the MTBE molecules simply flow through the carbon, as they resist adsorption or adherence to the surface of the activated carbon particles. What’s more, the MTBE molecules are competing, if you will, with other organic contaminants in water that bind much more readily with activated carbon. These other compounds can quickly block the available surfaces of carbon particles, making them unavailable to the more reluctant MTBE molecules. Studies of filter technologies for MTBE removal support the trickling—not the pumping under pressure—of water through the filtering medium to allow more time for MTBE to come in contact with and adsorb to the activated carbon particle surfaces.

So far, the most scientifically sound and economical MTBE removal system for home use appears to be one from a company that has engineered the very first filter components specifically for the removal of MTBE after the water is pre-filtered for removal of virtually all bacteria and most of the other organic contaminants as well as chlorine. The developer chose the Doulton® (British Berkefeld) Filter as the “host” filter unit because of its economy, its high efficiency and output and, most importantly, because of the Doulton® trickle technology that really lends itself to maximum MTBE adsorption.

These MTBE filters, containing a proprietary, ultra-high surface area medium, will screw onto the bottom of the existing Doulton® filter cones in the bottom chamber, receiving already-filtered water from the top chamber, and effectively remove MTBE molecules as the water trickles through into the bottom chamber. They have told me the filters will ship in 4–6 weeks, and I suspect they will be deluged with orders when especially hard-hit areas like California and New York get wind of it.

As more reliable technology for MTBE removal is developed, I will keep you posted. Ditto for more studies and conclusions on biological effects of MTBE as they come out. This issue has the potential to become a critical environmental and personal health crisis for the next ten, twenty or more years in the U.S. and anywhere else MTBE is currently leaking into water supplies. It deserves your attention.