Water officials wary of fuel additive
Once upon a time, oil refiners added lead to gasoline to improve its combustion and increase performance. After scientists learned that exposure to lead was harmful, environmental regulators outlawed its use as a fuel additive.
Now, the performance-enhancing additive that the oil industry substituted for lead has also come under fire, amid questions about its possible effect on human health and the threat it poses to the nation’s water supply.
“I am really concerned about our water supplies,” said state Sen. Richard Mountjoy, R-Arcadia, who is sponsoring a bill that would scrutinize the additive’s health impacts. “Putting MTBE into the water supply, where it has already been found, is absolutely crazy.”
Methyl tertiary butyl ether, known by the acronym MTBE, became the oil industry’s additive of choice even before the U.S. Environmental Protection Agency ordered the use of oxygen-rich additives in areas with high carbon monoxide levels.
Since 1979, MTBE has become one of the most widely manufactured organic compounds, with its production increasing by an annual average of 27 percent during the 1980s. Beginning in 1992, when so-called oxyfuels were introduced during the winter driving season, the use of MTBE has continued to increase. The oil industry has expressed a clear preference for the compound, which is derived from natural gas, over its main oxygenated rival, ethanol, an alcohol that is produced from farm crops.
While the widespread use of MTBE has alarmed some health researchers, water officials were slower to take notice. But some water suppliers have grown concerned with the special qualities of the additive that, they say, make it a unique risk to water resources.
The ether-based compound readily mixes with water and, once it does, tends to stay in the water. The chemical also resists adhering to soil and decomposition, allowing it to race through aquifers faster than any other constituent of gasoline.
Classified as a possible carcinogen, MTBE mixed in water triggers complaints over its turpentine-like smell and taste before reaching levels that are recognized as a health threat.
“We have a lot of concern with MTBE, and our concern is pretty high,” said Rick Hydrick, director of operations for the South Tahoe Public Utility District. The South Tahoe district is one of 15 water systems in the state to discover the additive in one of its drinking water supplies.
The South Tahoe district found the additive in one of its 35 wells. After closing the well for a time, the district began blending it with water from other wells, then removing the compound with the aid of a $450,000 air-stripping tower.
The only problem is that the MTBE resists air stripping, Hydrick said.
“We thought our stripping tower would buy us some time, but that may not be true,” he said.
Since state health officials ordered water suppliers to begin monitoring MTBE, just 27 water sources out of 2,200 have been found to be tainted. About one of every 30 water suppliers has reported some contamination.
But, so far, only 10 percent of the state’s water districts have reported results of the monitoring, and just 20 percent of all sources have been tested.
The additive has begun to show up in lakes and reservoirs as well, either from engine emissions, surface runoff or atmospheric deposition. Glenn Miller, a University of Nevada-Reno researcher, reported finding MTBE, along with other gasoline components, in Lake Tahoe following the busy Fourth of July weekend.
“The fact we found MTBE and other gasoline constituents, found them consistently, and found them at depth are a concern,” Miller said, adding that the concentrations found are mostly an aesthetic problem, as opposed to a health concern.
Miller reported finding MTBE in concentrations as high as 25 to 47 parts per billion in areas of high activity off South Lake Tahoe. The levels are below California’s interim health advisory level of 35 ppb, but above the threshold of taste and odor.
Yet, the benefits from the addition of oxygen-rich compounds justify the risk to water supplies, say proponents of the additive. They point to a nationwide program of identifying and fixing leaking fuel tanks as a safeguard to widespread problems from the additive, since leaking tanks are the primary hazard to water supplies.
“We feel the underground tank program is a key measure that will reduce all gasoline releases,” said Allan Hirsch, a spokesman for the California Air Resources Board.
A possible threat to underground fuel tanks, some automotive engineers contend, is the corrosive nature of MTBE and ethanol.
While the California State Automobile Association found no increase in the corrosion of car parts of its members, others say both MTBE and ethanol have caused headaches for automobile parts makers.
“It’s well-known that MTBE has a negative impact on elastomers, the pliable or rubber parts of cars,” said Robert Brooks, a member of the Society of Auto Engineers who writes for Ward’s Engine Update, an auto industry newsletter. “The older the (parts) are, the more they’re susceptible. In a general sense, we know there is a widespread problem, but the powers that be are doing what they can to make sure they are not known.”
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