"It's almost as if it's a secret, that they don't want to know about people who are affected," said Janet McIntyre, who lives near drilling areas north of Pittsburgh. "There's a lot of people in my neighborhood that have rashes and little red spots."
State officials say the air and water in the community are safe, and doctors have not confirmed that drilling caused illnesses. But without a full-scale medical review or other research in such cases, worries remain.
"Right now, the kind of comprehensive research that's needed just hasn't started," said Bernard Goldstein, professor emeritus at the University of Pittsburgh School of Public Health.
The drilling boom follows advances in hydraulic fracturing, or fracking, that have made enormous reserves of gas accessible, leading to more jobs and profits, and lower energy costs. But there are also concerns about pollution. The gas is pulled from the ground through a process in which large volumes of water, plus sand and chemicals, are injected deep underground to break rock apart and free the gas.
Environmentalists claim that the fracking fluids could rise and pollute shallow drinking water aquifers, and that methane leaks cause serious air pollution. The industry and many government officials say the practice is safe when done properly, and many communities welcome the jobs and royalty payments for landowners. But faulty wells have polluted water in some cases.
Scientists, residents and even some energy companies agree on one thing: Without credible answers, the fears and lawsuits over possible health and environmental impacts are likely to grow.
Disputes over possible effects on drinking water have already led to lawsuits in Pennsylvania, Texas and other states. In June, Oklahoma-based Chesapeake Energy agreed to a $1.6 million settlement with Pennsylvania families that say their wells were ruined, though the company did not acknowledge any fault.
One national law firm has created a website - www.fracking-lawsuit.com - to attract clients; another has www.frackinginjurylaw.com.
The federal Environmental Protection Agency has drafted new rules to better control air pollution from drilling, and officials in Pennsylvania and other states have tightened regulations on well construction and related issues. But critics say public health effects are being overlooked.
"There's literally hundreds of millions of dollars being spent on environmental health and human health research every year," Goldstein said, yet virtually none of it is to study gas drilling.
The Centers for Disease Control and Prevention said in January that research into fracking "should include all the ways people can be exposed" to fumes or tainted water. Yet more than a half-year later, "we don't have any new initiatives" regarding shale gas and public health, said Bernadette Burden, a CDC spokeswoman.
With a lack of government funding, there are some embryonic attempts to fill the gap. The nonprofit Environmental Defense Fund has said, without elaborating, that it was working with major universities and eight natural gas companies on ways to address environmental and health concerns.
Critics say the industry is not doing much to help the situation, especially given the enormous amounts of money shale gas is producing.
New shale gas fields generated more than $20 billion in gross revenue in 2011, according to an Associated Press analysis of federal energy data. That figure is projected to grow steadily over the next 10 years, even with wholesale prices that are near historic lows.
Reid Porter, a spokesman for the American Petroleum Institute, the leading industry group, said he was unaware of any API donations to public health research.
Goldstein, who has more than 40 years' experience working in public health, predicted that a failure to gather data now could in the future be used by trial lawyers seeking big payments from a deep-pocketed industry.
"If somebody in your community tells you that they're sure that they're sick, that their kids are sick, and at the same time the industry is saying, 'It ain't us,' who are you going to believe?" Goldstein said.
Energy companies can look at to at least one successful model for industry-supported research.
The Health Effects Institute, founded in 1980, is a Boston-based partnership between the EPA and the auto industry. Each contributes half of the yearly $10 million budget, said director Dan Greenbaum, but the industry has no say on what research projects get chosen.
The institute is "exploring the possibility" of helping shale gas drilling research, but ultimately that would require contributions from the gas-drilling industry, he said.
Some industry groups say they are ready to consider new approaches. Patrick Creighton, a spokesman for the Marcellus Shale Coalition, said it had worked with a number of institutions to advance original research. He provided no details.
Some recent research, though, has been tainted by industry money.
The University of Texas at Austin recently said it would create a group of outside experts to review the school's Energy Institute, which issued a report on environmental effects from gas this year without disclosing that an energy company was paying hundreds of thousands of dollars to the lead researcher.
A May report from the University at Buffalo generated similar controversy because of the researcher's ties to the gas industry.
The oil and gas companies and researchers who don't disclose their industry ties "just don't get" that a loss of credibility can cost more in lawsuits than funding tough, nonpartisan research, Goldstein said.
"Human nature," he said, "will not trust industry."