Dirk DeTurck had a years-old rash that wouldn't go away, his wife's hair came out in chunks, and anytime they lingered outside their house for more than an hour, splitting headaches set in.

They were certain the cause was simply breathing the air in Greenbrier, Arkansas, the rural community to which they'd retired a decade ago. They blamed the gas wells around them. But state officials didn't investigate.

So DeTurck leapt at the chance to help with research that posed a pressing question: What's in the air near oil and gas production sites?

The answer—in many of the areas monitored for the peer-reviewed study, published today in the journal Environmental Health—is "potentially dangerous compounds and chemical mixtures" that can make people feel ill and raise their risk of getting cancer.

"The implications for health effects are just enormous," said David O. Carpenter, the paper's senior author and director of the University at Albany's Institute for Health and the Environment.

The study monitored air at locations in five states: Arkansas, Colorado, Ohio, Pennsylvania, and Wyoming.

In 40 percent of the air samples, laboratory tests found benzene, formaldehyde, or other toxic substances associated with oil and gas production that were above levels the federal government considers safe for brief or longer-term exposure. Far above, in some cases.

The Independent Petroleum Association of America referred questions about the study to Energy in Depth, an outreach campaign it launched in 2009. Energy in Depth spokeswoman Katie Brown criticized the involvement of Global Community Monitor, the nonprofit that had trained DeTurck and other volunteers to gather the samples.

"It's difficult to see how Global Community Monitor, a group that dubiously claims no amount of regulation will ever make fracking safe, could make a constructive contribution within the scientific community," Brown said by email.

The study comes amid a growing body of research suggesting that the country's ballooning oil and gas production—often next to homes and schools—could be endangering the health of people living or working nearby. For the past 18 months, the Center for Public Integrity and InsideClimate News have been investigating this topic, focusing mainly on the Eagle Ford Shale formation of south Texas.

A study published in Environmental Health Studies in September found that Pennsylvania residents living less than two-thirds of a mile from natural gas wells were much more likely to report skin and upper-respiratory problems than people living farther away.

A Colorado School of Public Health analysis published in April found 30 percent more congenital heart defects in babies born to mothers in parts of that state with lots of gas wells than in babies born to mothers with no wells within ten miles of their homes.

And a 2013 study done for the state of West Virginia found benzene, a carcinogen, above levels considered safe by the federal Agency for Toxic Substances and Disease Registry near four of seven gas-well pads where air was sampled.

These findings come after years of little information beyond citizen complaints and industry reassurances. Scientists say the research is far from complete and more is urgently needed. (Related: "Health Questions Key to New York Fracking Decision, But Answers Scarce")

Researchers associated with the September and April studies, for instance, noted that their findings don't prove that gas production caused the health problems but instead flag a potential link that needs further investigation.

"Research is just now beginning really to be done," said Michael McCawley, interim chair of West Virginia University's Department of Occupational and Environmental Health Sciences and author of the 2013 study for that state.

"Part of the problem seems to be a concerted effort, up until recently, to avoid asking the question," said environmental physician Bernard Goldstein, a faculty emeritus at the University of Pittsburgh who served as an U.S. Environmental Protection Agency official during the Reagan Administration.

View Images A canal carries wastewater from fracking in Park County, Wyoming. Some residents are concerned that oil and gas drilling operations are sending toxic chemicals into the air. Photograph by Deb Thomas, Shaletest

But a shift is under way. The National Institutes of Health's National Institute of Environmental Health Sciences says it's supporting nine studies that are in progress, from an analysis of asthma near shale-gas sites to an examination of local residents' health before, during, and after a multiwell pad is constructed. The agency is also conducting its own studies on chemical exposures that could be an issue for gas-extraction workers and people living near such sites.

The industry has been largely dismissive of the research already released.

"We have not seen credible studies showing natural gas production causes health effects," Dan Whitten, a spokesman for trade group America's Natural Gas Alliance, said by email. "Obviously, we are sympathetic to anyone with health concerns. Our members remain committed to the development of natural gas in a safe and responsible manner."

The American Petroleum Institute did not respond to repeated requests for comment. But McCawley said the industry group alerted researchers this past summer that it would be funding a health-effects study.

Scientists Team With Citizens

For the new Environmental Health study, academics teamed up with Global Community Monitor (GCM) and volunteers it trained. The group, founded 13 years ago, had developed a process that enabled residents to sample the air in their own neighborhoods.

That's an unusual setup for a peer-reviewed study, but it was by design, said the University at Albany's Carpenter. Deploying residents allowed for quick monitoring in places where a problem was suspected, based on, for example, bad odors or symptoms such as nausea.

Energy in Depth, which has criticized other studies that looked at potential health effects near oil and gas production, focused on Global Community Monitor rather than the findings. (Related: "Methane on Tap: Study Links Pollution to Gas Drilling.")

"Their founder has even admitted that, in their activism, science takes a back seat to 'organizing,'" spokeswoman Katie Brown said by email. "For groups financed by the same foundations that fund GCM, that all may be something to dismiss or ignore, but for those of us interested in actually understanding development better—and not just creative ways to undermine the safety record of hydraulic fracturing—it's important that we focus on science, not activism." (Take the quiz: "What You Don't Know About Natural Gas.")

Denny Larson, Global Community Monitor's founder and executive director, said by email that he believes science "should be purpose driven to discover the truth."

He added, "It's clear that the oil and gas industry wants to use the same tired strategies to discredit sound science, just as the tobacco companies did in the past."

The study's sampling was done as a snapshot—air at one moment in time or, in the case of formaldehyde, over the course of at least eight hours. Carpenter said that's not how states have typically handled their own monitoring, the results of which have suggested there was little cause for alarm or weren't detailed enough to determine whether a health risk existed.

By averaging the results over days, weeks, or months, he said, state monitors risk missing the sporadic emission spikes that can harm exposed people. As Carpenter noted, "Our results indicate that the longer-term monitoring misses peak concentrations, which may be very important."

Toxic substances in 20 percent of the 76 samples taken for the study exceeded safe levels for brief exposure; another 20 percent exceeded standards for longer-term exposure. The study's authors said they thought both were appropriate measurements, in part because residents picked areas to sample where odors and health complaints were common.

Gregg Macey, one of the study's co-authors and an associate law professor at Brooklyn Law School whose area of expertise includes environmental regulation, said he sees its value less in the specific findings—though he called them "troubling"—than in the road map the research offers. "The key takeaway is we really need to start sampling at the scales dictated by community concerns, the same concerns that are sometimes lodged in county and state agencies as complaints but that are experienced daily."

The study sampled air near a mix of sites, including compressor stations, production pads, and condensate tank farms. Some, though not all, of the sampling sites were associated with hydraulic fracturing. (See: "The New Oil Landscape.")

In recent years this technique, often known as fracking, has opened the floodgates for trapped oil and gas by pummeling rock with a high-pressure mixture of water, sand, and chemicals. (Vote and comment: How Has Fracking Changed Our Future?)

Industry groups have pointed to the boom as an economic godsend, bringing jobs, cheaper energy, payments to landowners, and taxes to state coffers. Many public officials in those states—both Republicans and Democrats—see it that way too.

When the EPA indicated to Wyoming officials in 2011 that fracking had likely contaminated groundwater near the tiny community of Pavillion, the reaction was horror—at the potential impact on fracking.

Thomas Doll, then the state's oil and gas supervisor, testified on Capitol Hill several months later that Wyoming had received about two billion dollars in taxes and royalties during fiscal year 2010 from oil and natural gas work. Almost all of that was connected to fracking, and he blasted the EPA for what he called the "questionable" science of its nearly three-year review.

"The EPA conclusion that hydraulic fracturing caused ground water contamination is limited to the data found in a single sample detect from [a] single monitoring well," said Doll, the governor's representative at the hearing, in written testimony to the House Subcommittee on Energy and the Subcommittee on Environment. "Yet this fact is lost in the public reaction to EPA's announcement and results in a worldwide damnation of hydraulic fracturing."

Doll resigned in 2012, after saying that Pavillion-area residents pressing for action on their water wells were motivated largely by "greed." Yet after a year and a half of sustained political pressure following its draft review, EPA turned the investigation over to the state.

The state's investigation received funding from Encana, the energy company residents had accused of contaminating the water. "There was no one else stepping forward to provide funding for a study that needed to be done," said Doug Hock, a spokesman for Encana. "We certainly have a stake in this in a sense that we firmly believe this was not due to our operations ... This is an area that has had ... naturally occurring, historically, poor water quality."

EPA spokesman Rich Mylott said the agency stands by the work it did in Pavillion "but recognized the state's commitment to additional investigation to advance the understanding of groundwater quality in the area."

A draft report of the first stage of the state's study, released in August, said there was no evidence tying gas wells to the fouled water. Two other avenues of investigation continue.

Jerimiah Rieman, Wyoming's natural resource policy director, acknowledged that the state is highly dependent on oil and gas development for revenue, but he said officials truly do want to know what caused the problems in Pavillion. The state won kudos from the Environmental Defense Fund a year ago, after it set new rules requiring oil and gas operators to collect water samples before and after drilling.

"Long after our minerals are gone," Rieman said, "we'd better have water to survive."

Pressing for Air Monitoring

People were driven to help with the air-emissions study in the five states—including Wyoming—by a deep suspicion that their state governments were failing to protect public health.

Deb Thomas, who, at 60, has spent years working as a community organizer on pollution matters in Wyoming, said concerns about air followed the water worries. People told her they'd lost their sense of smell and taste. She heard complaints about headaches and breathing problems as well as reports of miscarriages, neuropathy, unusual cancers, and autoimmune diseases.

Starting in 2007, she pressed for state air monitoring in Pavillion. The state brought in a mobile monitor designed primarily to measure ozone, not the specific types and amounts of harmful volatile organic compounds that might be in the air.

Keith Guille, a spokesman for the Wyoming Department of Environmental Quality, said that volatiles contribute to ozone and that a year of monitoring had found no ozone problems.

Thomas—then at the conservation-focused Powder River Basin Resource Council and now director of ShaleTest, an environmental-data-collection nonprofit based in Texas—wasn't satisfied. "We knew people were getting really sick, and more and more data started coming out about air issues, and the state refused to do any real testing," she said. "And so we decided we would start doing some testing ourselves.

She called Global Community Monitor. The group told her about a study just getting under way. Would she like to participate?

Thomas rounded up people to collect samples in four areas and ended up as a co-author on the study. It found that many of the Wyoming samples contained volatile organic compounds above safe levels—particularly hydrogen sulfide, a naturally occurring gas that can be released by drilling and can cause headaches, dizziness, nausea, and, in sufficient concentration, death.

View Images Waste pits sit on a natural gas drilling pad in Park County, Wyoming. Photograph by Deb Thomas, Shaletest

She expected to find problems in Pavillion. What startled her were the results around her own town, Clark, where tests of the air samples showed high levels of benzene, a chemical that can be emitted by oil and gas production.

The worst sample had 110,000 micrograms per cubic meter of air, 12,000 times the safe level for brief exposure set by the federal Agency for Toxic Substances and Disease Registry. Several other Wyoming samples also tested high for benzene, though far lower than the worst one.

A 2006 blowout at a gas well near Clark had made Thomas seriously concerned about air problems: She'd ended up in the emergency room a few days later with her first, and only, asthmatic episode. But she said she didn't expect much in the way of dangerous compounds there years later.

"In the area where I live, there's only six wells producing right now ... and they're very low producers," she said. "I thought, Oh, we're not going to find anything here because there's not much going on. And then it was off the charts."

In Desperate Search of Data

In Pennsylvania's Susquehanna County, six of the air samples shipped off for testing contained high levels of formaldehyde, classified as a carcinogen by the World Health Organization. All had been taken near compressor stations, which pressurize natural gas so that it can flow through pipelines. Formaldehyde can be a by-product of the facilities' engines.

Breathe Easy Susquehanna County coordinated the local sampling. Rebecca Roter founded the grassroots group last year to lobby gas companies for better pollution controls, and she knew data would be critical. Air sampling the state had done in her county had struck her as woefully inadequate.

"It was too late for a baseline, because we're seven years into shale development in Susquehanna County, so we were desperately trying to do what we could to document anything," said Roter, 53, who lives in Brooklyn, Pennsylvania. "The best way to have a real discussion about what's really happening is to have the facts."

Three years ago, when she first smelled a bad odor drifting from a compressor station several miles from her home, she filed a complaint with the Pennsylvania Department of Environmental Protection. By the time a field agent got back to her a week later, she said, the smell was gone, and he wasn't interested—an experience she said has proved typical in the state, even though not all chemicals and gases have an odor.

"The field rep said, Well, if it doesn't smell, it's a dead end," Roter said. "And he accused me of driving around to find smells."

Colleen Connolly, a spokeswoman for the Pennsylvania Department of Environmental Protection, said agency employees recall an inspector going to Roter's home and noticing no odor, but they haven't been able to locate the complaint record.

Connolly said by email that the state has air-monitoring units in two towns, one of which is in Roter's county, that take air samples once a week near compressor stations. She noted that the agency doesn't monitor near gas wells except after complaints. "It is up to the individual gas company to monitor for VOC ... emissions [and] report those findings to DEP," she said.

Emily Lane, an Arkansas graduate student who helped with the air monitoring in her state, hopes the emissions study will spur Arkansas to do its own monitoring at all oil and gas sites. She said that a top official at the state Department of Environmental Quality agreed to meet with her about the findings if they were published in a scientific journal.

Lane wishes the air-sample results themselves, available in March, had been reason enough for the state to look more closely, since they showed high levels of formaldehyde.

Katherine Benenati, a spokeswoman for the Arkansas Department of Environmental Quality, said the agency is happy to review outside data once a study is completed—and peer reviewed.

When the agency did its own gas-site monitoring in 2010 and 2011, it measured total volatile organic compounds but not the individual types or amounts. That made it impossible for the researchers to say whether any posed a hazard.

Their report concluded, "Future studies should monitor air quality with instruments that can detect lower concentrations of pollutants and identify individual VOC compounds to determine if the emissions from gas sites are potentially harmful to public health and welfare."

According to the agency, no follow-up studies have been launched in the three years since, and none are planned.

"The statement in the executive summary is an indication of a limitation of the data that was gathered in the study," Benenati said in an email. "It was not meant to suggest that additional data gathering was being recommended."

DeTurck, the Arkansas retiree, has his own take on that: "There's no problem if you never really look for it."

He said he and other residents have spent three years asking state officials to do something in Greenbrier. The state did shut down injection wells blamed for setting off more than a thousand small earthquakes in his county, he said, but that was it.

"The state's all in on this industry," said DeTurck, who's 59. "One legislator ... told me to my face, If you don't like it, move, because that's the future."

DeTurck followed that advice, though it took three years to find a buyer. He and his wife, Eva, moved 12 miles south in December. Given the direction the winds blow there, they figured that was enough distance to get cleaner air.

DeTurck said his wife's hair loss, ringing in the ears, and headaches stopped within two weeks. His rash cleared up several months later, he added, and his other symptoms dissipated too.

"I don't miss those headaches and nosebleeds and the rash and the smell-the putrid smell," he said. "Every morning, every night."

This story was published by the Center for Public Integrity, a nonprofit, nonpartisan investigative news organization in Washington, D.C.