By Tom Davey
When a 60 MinutesTV program reported that methyl tertiarybutyl ethermight have contaminated thousands of ground-water drinking water sources, it generated widespread concern across North America.
MTBE was mandated by the EPA as a gasoline additive to reduce air pollution in targeted states and areas. The initiative was announced by the then President, George Bush, as a step forward in curbing a serious problem which affects human health. While undeniably effective in curbing air pollution, the chemical compound could pose a serious threat to humans when it contaminates drinking water sources from leaking underground gasoline tanks. The problem is compounded by the mobility of MTBE in its migration through soils to groundwaters.
MTBE is part of reformulated gasoline,made to boost the amount of oxygen in gas, causing it to burn more cleanly in automobiles. Such reformulated fuels typically may contain up to 15 percent of MTBE. For those auto manufacturers using the compound only to boost octane, the MTBE content may only range from two to eight percent.
In 1998, a report to the US Environmental Protection Agency recommended state and federal action to better safeguard drinking water supplies from gasoline additives such as MTBE while noting that such additives did help to reduce air pollution. The US EPA classified MTBE as a possible human carcinogen and had a draft health advisory for drinking water of 20 to 40 µg/l or parts per billion (ppb). California state action levels have been established at 35 ppb.
Recent nationwide sampling programs conducted by the US Geological Survey have detected MTBE in both groundwater and stormwater. Possible sources of MTBE in shallow groundwater include direct contamination from leaking storage tanks and indirect contamination from stormwater flow and precipitation washing through urban atmospheres.
This report was begun in Florida where Charles Vogt, environmental health specialist with the Indian River County Health Department, was quoted as saying that all municipal water supplies in the state had been checked for MTBE. Indian River County utilities' test results in April 1999 - long after the compound was in use - showed no detectable levels. Mr. Vogt noted that new regulations required gasoline storage tanks to be both double-walled and corrosion-resistant. Tanks must also be equipped with electronic leak detectors. He added that US federal law also required fuel tank owners to carry insurance which would cover leakage damage costs, so removing any financial incentives to hide problems.
The Florida standard for MTBE is 35 parts per billion, based on taste and odour thresholds, not health concerns.
EPA literature describes MTBE as a 'potential' human carcinogen. Studies have yet to be completed to determine if the compound causes cancer in humans. The EPA report suggests that were it to be shown to cause cancer in humans, "the dosage required would be much higher than the levels at which the compound could be tasted or smelled in drinking water."
Meanwhile, the Canadian Water & Wastewater Association recently reported that tests in Calgary drinking water found no traces of MTBE. A spokesman for Calgary Water Works said: "If gasoline companies are using the additive, it doesn't show up on the city's detection systems." He said the absence of MTBE could be because of stringent buried-tank maintenance requirements in Alberta, plus the fact that Calgary derives its drinking water from surface sources like lakes and rivers.
Calgary began testing for MTBE in 1997 and reviewed 1996 data. They can detect MTBE concentrations of as little as five parts per billion, but, so far, have found none. According to the CWWA newsletter, a spokesman for Shell Canada said his company uses another additive called MMT (methylcyclopentadienyl manganese tricarbonyl), over MTBE, to enhance octane levels.
From our enquiries, it appears that:
So, in trying to ban MMT, the Canadian government would have caused another problem, which, for the most part, we have avoided in Canada. The oil industry was already aware of the MTBE issues when MMT was under review and that was one reason why they were against the ban.
Copyright Tom Davey, all rights reserved.
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