A private group that has been critical of natural gas operations says recent testing found "elevated" levels of benzene at two area sites, including one in Fort Worth.
ShaleTest said Wednesday that its own short-term test near a pipeline compressor station in the Denton County community of Dish found that benzene, a carcinogen, exceeded the state's threshold for long-term exposure. ShaleTest, whose organizers include former Dish Mayor Calvin Tillman, also said the Texas Commission on Environmental Quality found a similar level of benzene at a site near downtown Fort Worth after making an inspection in response to the group's complaint.
The state agency, however, said the levels measured at either site would not present health problems unless they persisted for decades, although it plans to conduct follow-up tests at the Fort Worth site. It made two tests at the Fort Worth site, one lasting 30 minutes and one lasting eight seconds, to account for shifting winds.
The agency sets thresholds for long-term and short-term exposures to benzene and other substances that carry health risks. The long-term risk threshold for benzene -- defined as the average annual exposure needed to produce one additional cancer case among 100,000 people exposed continuously for their lifetimes -- is 1.4 parts per billion. The short-term threshold, defined as one hour and capable of producing temporary conditions like headaches or dizziness, is 180 ppb.
ShaleTest said its short-term test Oct. 28 found a concentration of 3.8 ppb downwind of a Kinder Morgan compressor station in Dish. The state agency's 30-minute test of a Texas Midstream Gas Services compressor station found a benzene concentration of 1.5 ppb, and its eight-second test measured 4.1 ppb. TCEQ visited that site, just west of Interstate 35W and north of East Belknap Street, on Oct. 31.
Tillman said Thursday homes are near both sites, and a city park near the Fort Worth site, "so they're being exposed pretty consistently."
The agency's inspection found that the site was operating within the emission levels allowed by its permit, but recommended future tests because of the benzene reading.
In a response to ShaleTest's report, agency spokesman Terry Clawson said "it is not scientifically appropriate to compare" short-term test results against long-term thresholds. He said the agency has a network of monitors in the area that constantly test for dozens of chemicals.
Tillman said his group also noted but did not measure emissions from a number of other natural gas sites in the Barnett Shale.
"The public bodies aren't doing what they need to do to protect us," he said.