By KEVIN BEGOS
PITTSBURGH (AP) - In the debate over natural gas drilling, the companies are often the ones accused of twisting the facts. But scientists say opponents sometimes mislead the public, too.
Critics of fracking often raise alarms about groundwater pollution, air pollution, and cancer risks, and there are still many uncertainties. But some of the claims have little _ or nothing_ to back them.
For example, reports that breast cancer rates rose in a region with heavy gas drilling are false, researchers told The Associated Press.
Fears that natural radioactivity in drilling waste could contaminate drinking water aren't being confirmed by monitoring, either.
And concerns about air pollution from the industry often don't acknowledge that natural gas is a far cleaner burning fuel than coal.
"The debate is becoming very emotional. And basically not using science" on either side, said Avner Vengosh, a Duke University professor studying groundwater contamination who has been praised and criticized by both sides.
Shale gas drilling has attracted national attention because advances in technology have unlocked billions of dollars of gas reserves, leading to a boom in production, jobs, and profits, as well as concerns about pollution and public health. Shale is a gas-rich rock formation thousands of feet underground, and the gas is freed through a process called hydraulic fracturing, or fracking, in which large volumes of water, plus sand and chemicals, are injected to break the rock apart.
The Marcellus Shale covers large parts of Pennsylvania, New York, Ohio and West Virginia, while the Barnett Shale is in north Texas. Many other shale deposits have been discovered.
One of the clearest examples of a misleading claim comes from north Texas, where gas drilling began in the Barnett Shale about 10 years ago.
Opponents of fracking say breast cancer rates have spiked exactly where intensive drilling is taking place _ and nowhere else in the state. The claim is used in a letter that was sent to New York's Gov. Andrew Cuomo by environmental groups and by Josh Fox, the Oscar-nominated director of "Gasland," a film that criticizes the industry. Fox, who lives in Brooklyn, has a new short film called "The Sky is Pink."
But researchers haven't seen a spike in breast cancer rates in the area, said Simon Craddock Lee, a professor of medical anthropology at the University of Texas Southwestern Medical Center in Dallas.
David Risser, an epidemiologist with the Texas Cancer Registry, said in an email that researchers checked state health data and found no evidence of an increase in the counties where the spike supposedly occurred.
And Susan G. Komen for the Cure, a major cancer advocacy group based in Dallas, said it sees no evidence of a spike, either.
"We don't," said Chandini Portteus, Komen's vice president of research, adding that they sympathize with people's fears and concerns, but "what we do know is a little bit, and what we don't know is a lot" about breast cancer and the environment.
Yet Fox tells viewers in an ominous voice that "In Texas, as throughout the United States, cancer rates fell _ except in one place_ in the Barnett Shale."
Lee called the claims of an increase "a classic case of the ecological fallacy" because they falsely suggest that breast cancer is linked to just one factor. In fact, diet, lifestyle and access to health care also play key roles.
Fox responded to questions by citing a press release from the Centers for Disease Control and Prevention that doesn't support his claim, and a newspaper story that Risser said is "not based on a careful statistical analysis of the data."
When Fox was told that Texas cancer researchers said rates didn't increase, he replied in an email that the claim of unusually high breast cancer rates was "widely reported" and said there is "more than enough evidence to warrant much deeper study."
Another instance where fears haven't been confirmed by science is the concern that radioactivity in drilling fluids could threaten drinking water supplies.
Critics of fracking note the deep underground water that comes up along with gas has high levels of natural radioactivity. Since much of that water, called flowback, was once being discharged into municipal sewage treatment plants and then rivers in Pennsylvania, there was concern about public water supplies.
But in western Pennsylvania, the Pittsburgh Water and Sewer Authority did extensive tests and didn't find a problem in area rivers. State environmental officials said monitoring at public water supply intakes across the state showed non-detectable levels of radiation, and the two cases that showed anything were at background levels.