Studies continue as federal government reviews upgrading possible links to
Albany Times Union, Matt Pacenza
Published April 8, 2006
For most of the past 15 years, MTBE was the second-most-plentiful organic chemical used in the United States -- second only to ethylene, the main ingredient in plastic -- yet no one can say how toxic or dangerous MTBE is.
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Experts agree that there has simply not been enough research on MTBE.
It's a striking conclusion, given that most adult Americans have inhaled MTBE while pumping gasoline. And because the contaminant moves quickly from leaking underground gas tanks into groundwater supplies, millions have consumed at least small amounts of MTBE, some for many years, some at high levels.
At least 15 million Americans in 28 states have drunk MTBE-tainted water, according to an analysis by the Environmental Working Group, a Washington, D.C.-based organization that works on drinking water contamination. That number only accounts for people on public water supplies. No one knows how many of the estimated 42 million people who drink from their own wells are consuming MTBE.
Given the lack of comprehensive research on MTBE, researchers evaluating the additive rely on a handful of experiments done on mice and rats. The animals either inhaled MTBE or were force-fed it.
Some of the mice and rats got cancer. Various studies have found that MTBE led to kidney cancers, liver cancers, testicular cancer in the male rodents and lymphatic cancers in the females. Much of this research was done by the Collegium Ramazzini, an Italian-based consortium of toxicologists that has won widespread respect for its groundbreaking work demonstrating the harm of certain chemicals, from vinyl chloride to the artificial sweetener aspartame.
Its findings led a panel of researchers, charged in 1998 with analyzing MTBE for the California governor and legislature, to conclude "MTBE is an animal carcinogen with the potential to cause cancer in humans." The same conclusion has been reached by every major body that has studied the evidence, such as the U.S. Environmental Protection Agency and the White House National Science and Technology Council. That was the current word on MTBE -- a "potential carcinogen" -- until
last year.
A pair of reports have surfaced indicating that the EPA is about to
reclassify MTBE as a "likely carcinogen." Sources within the agency told Steve Gibb, the editor of "Inside EPA's Risk Policy Report," that agency staff were in the midst of reviewing a new assessment of MTBE.
Bill Walker of the Environmental Working Group checked in with his own
sources at the agency. They confirmed Gibb's report. The new risk
assessment, which has been circulating within the EPA for over a year, will conclude that MTBE has roughly the same toxicity as benzene, according to Walker. Benzene is a known carcinogen for which the EPA has set a maximum level in drinking water of 5 parts per billion -- twice as protective as any state's limit on MTBE.
Gibb and Walker disagree about why it has taken the EPA more than a year to issue its new assessment of MTBE. Gibb said there is nothing unusual about taking that long to evaluate a new policy. For Walker, it's an example of the Bush administration quashing research that is bad for industry.
"It's harder and harder to get science out that is making strong statements which might increase regulations," Walker said.
EPA officials confirmed they are taking another look at MTBE, but would not say what they've concluded.
"We are in the process of reviewing it internally," said Peter Preuss,
director of EPA's National Center for Environmental Research. A draft for public comment will likely be out this fall, he added.
Other studies on MTBE have looked at health impacts beyond its link to
cancer. A Finnish research project studied 101 truck drivers who inhaled MTBE while delivering gasoline containing 10 percent of the additive. The drivers reported increased fatigue, hostility, headache, nausea, salivation, dizziness and labored breathing, although the symptoms did stop after work, suggesting the side effects were temporary.
Several other studies, all peer-reviewed scientific research, have found that inhaling MTBE increases kidney lesions and swells the liver, kidney and tissues around the eye. The most striking finding is that breathing in MTBE gave male rats chronic kidney disease.
Those who doubt MTBE poses a serious human health threat note that in the cancer studies, the animals ingested large amounts of the toxin before they developed problems. In the rat studies, for example, the rodents were fed approximately 400,000 parts per billion before they got cancers, levels much higher than what anyone could ever drink. That's what led researchers like Arturo Keller, a biogeochemistry professor at University of California at Santa Barbara, to say MTBE is "not a very toxic compound."
Those who say MTBE poses a minimal threat also argue that it tastes and
smells so bad -- like gas or turpentine -- no one would drink it at very high levels for very long. If a well is significantly tainted, the thinking goes, residents will get it tested or go out and buy bottled water. But research shows not everyone is so sensitive, and some people will in fact drink MTBE at levels way above New York's safety limit without realizing. Some people, research shows, can't taste MTBE until levels reach 680 parts per billion or smell it until 190 parts per billion, according to an analysis of several studies by the University of California Toxic Substances Research and Teaching Program.
Those worried about MTBE also argue cancer studies are an extremely crude tool for measuring effects on health. Such research doesn't look for other changes in the body, such as possible effects on the brain. They point to a new wave of toxicological research, which suggests some compounds -- even in minute quantities -- have profound effects on the body if ingested at certain critical moments, such as by a pregnant woman during the early stages of fetal development.
A biologist at the University of Missouri, Frederick Vom Saal, has led
studies that concluded trace amounts of hormones can permanently alter the reproductive system in mice. He also has done research showing how chemicals such as plastics can mimic hormones.
Those findings and others have led many environmentalists and public health experts to embrace what's being called the precautionary principle: when uncertainty about a compound remains, it should be treated as dangerous.
Such caution is a wise way to approach MTBE, many environmentalists believe. "We shouldn't be mixing infant formula with water that has any in it," said Richard Wild, a senior vice president at the Environmental Working Group. "Why should we? Because industry says they really haven't studied it enough to find problems?'
