Arizona May Follow California's Lead In Phasing Out Dangerous Chemical


A gasoline additive found in two of Payson's production wells has brought a contamination issue that California has struggled with to the Rim country.

Methyl-tertiary butyl ether (MTBE) has already contaminated several surface and groundwater supplies all over California, forcing that state to phase out use of the chemical intended to reduce air pollution.

According to ADEQ spokesperson Sina Matthes, legislation is in the works to rid Arizona of the chemical.

"House Bill 1504, that was proposed in 2000, will phase out MTBE," Matthes said. "We are working on phasing it out."

MTBE gets into groundwater supplies most often due to leaking underground storage tanks containing gasoline. Federal legislation now requires that underground tanks be certified and conform to tighter standards of construction to prevent leaks. However, a window of several years was allowed to comply with new regulations, ample time for groundwater contamination to occur.

While the Environmental Protection Agency does not have a national standard for "safe" levels of MTBE in drinking water, research scientists from several branches of the University of California completed a 10-month study that suggests that MTBE is linked to adverse health and environmental effects.

According to the study, there is no human data to evaluate if MTBE causes cancer in humans, however, the study did show an increase in cancer in mice and rats.

"Substantial evidence from studies of chronic exposure by either oral or inhalation routes demonstrate that MTBE is carcinogenic in rats and mice," the report states. "We conclude that MTBE is an animal carcinogen with the potential to cause cancer in humans."

The report went on to state that it is unclear how MTBE causes cancer. The report addressed the movement of MTBE in groundwater and its potential impact on water supplies. The characteristics of MTBE allow it to move quickly and resist absorption into the soil, therefore, a contamination plume can spread farther and faster than many other contaminants.

One model used in the study predicted that an MTBE release in 1996 could result in a 2,000-foot plume by 2010 that would encompass 100,000 acre-feet.

Fortunately, according to Matthes, rural areas such as Payson would only receive gas with MTBE if a station ran out and had to get a delivery from Phoenix.

"Typically, areas like Show Low and Payson get gas straight from the refineries and it would not have MTBE in it," Matthes said. "But if, for some reason, they had to get gas delivered from Phoenix, it would have MTBE in it."

If Arizona does follow California's lead in phasing out MTBE, the study's model indicates it will remain a potential groundwater contaminant for years to come.

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