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.
Concerns about the potential problem also led to regulatory changes. An analysis by The Associated Press of data from Pennsylvania found that of the 10.1 million barrels of shale wastewater generated in the last half of 2011, about 97 percent was either recycled, sent to deep-injection wells, or sent to a treatment plant that doesn't discharge into waterways.
Critics of fracking also repeat claims of extreme air pollution threats, even as evidence mounts that the natural gas boom is in some ways contributing to cleaner air.
Marcellus air pollution "will cause a massive public health crisis," claims a section of the Marcellus Shale Protest website.
Yet data from the U.S. Energy Information Administration show that the shale gas boom is helping to turn many large power plants away from coal, which emits far more pollution. And the U.S. Environmental Protection Agency passed new rules to force drillers to limit releases of methane from wells and pumping stations.
Some environmental groups now say that natural gas is having a positive effect on air quality.
Earlier this year, the group PennFuture said gas is a much cleaner burning fuel, and it called gas-fired power plants "orders of magnitude cleaner" than coal plants.
Marcellus Shale Protest said in response to a question about its claims that "any possible benefit in electric generation must be weighed against the direct harm from the industrial processes of gas extraction."
One expert said there's an actual psychological process at work that sometimes blinds people to science, on the fracking debate and many others.
"You can literally put facts in front of people, and they will just ignore them," said Mark Lubell, the director of the Center for Environmental Policy and Behavior at the University of California, Davis.
Lubell said the situation, which happens on both sides of a debate, is called "motivated reasoning." Rational people insist on believing things that aren't true, in part because of feedback from other people who share their views, he said.
Vengosh noted the problem of spinning science isn't new, or limited to one side in the gas drilling controversy. For example, industry supporters have claimed that drilling never pollutes water wells, when state regulators have confirmed cases where it has. He says the key point is that science is slow, and research into gas drilling's many possible effects are in the early stages, and much more work remains to be done.
"Everyone takes what they want to see," Vengosh said, adding that he hopes that the fracking debate will become more civilized as scientists obtain more hard data.
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