Texas state Sen. Wendy R. Davis is calling for an investigation on the environmental impacts from Barnett Shale drilling operations after ambient air data collected by state regulators found harmful concentrations of benzene at some drilling locations.

Davis, who represents Fort Worth, TX, first requested an interim study on the Barnett Shale in September to review, among other things, "the various environmental impacts related to the gas production processes in the Barnett Shale area and other similar fields using inputs from industry, the public, municipalities, county governments and departments of higher education."

However, she submitted a second request in a letter to Texas Lt. Gov. David Dewhurst on Monday requesting a special Senate investigation after recent ambient air data collected in the Barnett Shale area by the Texas Commission on Environmental Quality (TCEQ) and Wolf Eagle Environmental Engineers found "alarming" benzene concentrations at some drilling locations.

The benzene levels were discovered as part of a larger study on emissions being conducted in the region using an infrared camera that identifies heat. Long-term exposure to benzene has been linked to leukemia.

"Significantly, TCEQ's summary of those reports indicate a concern by their toxicology division that 'the monitored concentrations of benzene at several of the sampling locations could pose a long-term health risk to residents in the area if the concentrations are representative of normal and prolonged ambient conditions," she wrote.

The TCEQ summary stated that it "is possible that adverse health effects could occur from exposure to this concentration of benzene." The regulatory agency's toxicology division "strongly recommends additional sampling in the area."

According to Michael Honeycutt, who heads TCEQ's toxicology department, the commission is continuing to collect ambient air data in the Barnett Shale area, including Tarrant, Wise, Denton, Parker and Johnson counties.

"It is my hope that an interim study would include, but not be limited to, input from members of the environmental science community, members of the drilling industry and members of the [state] Senate who represent areas of Barnett Shale drilling activity," Davis wrote. "It is imperative that objective information be advanced that would serve as the basis of pollution control methods that should be utilized."

Dewhurst's office had not issued a response to Davis' request on Tuesday.

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