Radon levels in buildings near unconventional natural gas development in Pennsylvania are higher than those in other areas of the state, suggesting that hydraulic fracturing has opened up new pathways for the carcinogenic gas to enter people’s homes, according to a study published on Thursday. Radon is the second leading cause of lung cancer worldwide.
Researchers from Johns Hopkins University analyzed radon readings taken in some 860,000 buildings, mostly homes, from 1989 to 2013 and found that those in rural and suburban areas where most shale gas wells are located had a concentration of the cancer-causing radioactive gas that was 39 percent higher overall than those in urban areas.
It also found that buildings using well water had a 21 percent higher concentration of radon than those served by municipal water systems.
And it showed radon levels in active gas-drilling counties rose significantly starting in 2004 when the state’s fracking boom began.
Overall, 42 percent of the buildings analyzed had radon concentrations at over 4 picocuries per liter, the level at which the U.S. Environmental Protection Agency recommends remediation, and which is about three times the national average for indoor air. According to the EPA, there are about 21,000 radon-related lung cancers per year in the U.S.
The new study was based on data collected from the DEP which requires the reporting of radon tests, many of which are done when houses are bought or sold. The project was conducted with the Geisinger Health System, and is the first part of a long-term investigation of the health effects of unconventional gas development being done by Geisinger, based in Danbury, northeastern Pennsylvania.
But the study, titled “Predictors of Indoor Radon Concentrations in Pennsylvannia 1989-2013,” released today in the journal Environmental Health Perspectives, a publication put out by the National Institutes of Health, contradicts a report released by the Pennsylvania Department of Environmental Protection in January.
The DEP spent more than a year studying exposure risks to naturally occurring radioactive material (NORM) during oil and gas production and concluded there is “little potential for harm to workers or the public.”
Ken Reisinger, DEP’s acting deputy secretary for the office of waste, air, radiation and remediation, says the two studies are not comparable because they take their measurements of radon from two different things. Reisinger says he was not directly involved in the DEP study, but kept tabs on it.
“Our sampling was conducted at well pads, landfills, at areas where either the activities were taking place, or where the materials were being transported to,” Reisinger told StateImpact. “We were looking at primarily ambient air samples near operating wells. We were looking at radon in the natural gas extracted from the wells. We were looking at residual solids. We did not look at indoor radon with the exception of looking at any potential associated with using the gas for cooking or heating.”
The DEP study was led by former deputy secretary Vince Brisini, who was hired under the Corbett Administration but has since left the DEP for the private sector. Reisinger, his replacement, says he’s confident in the Department’s analysis.
“I believe the people that conducted the study did it well,” said Reisinger. ”I know there was a lot of effort into writing the final document. It went through a very thorough editing and revision process to make sure we got things right. It was peer reviewed. I feel good about it.”
The Johns Hopkins study, which claimed to be the first to examine predictors of radon in buildings across Pennsylvania, concluded that the presence of the inert gas was related to geology, water sources, and weather, as well as gas development.
But it highlighted natural gas drilling in the Marcellus Shale as a possible cause of the higher radon levels.
“One plausible explanation for elevated radon levels in people’s homes is the development of thousands of unconventional natural gas wells in Pennsylvania over the past 10 years,” said study leader Dr. Brian Schwartz, a professor in the Department of Environmental Health Sciences at the Johns Hopkins Bloomberg School of Public Health.
Schwartz told StateImpact that there was information on other possible sources of radon that researchers didn’t have and would have liked.
“There were several pieces of information we would have wanted but didn’t have, such as whether the building had gas heating or cooking, foundation cracks, radon remediation, or radon-resistant construction,” Schwartz wrote in an email.
The study did not examine any health effects on people living in houses with elevated radon, Schwartz said.
Pathways for the radioactive gas to get into people’s homes from drilling and fracking operations may include well water, air, or natural gas itself when it is used for heating and cooking, said Joan Casey, an author of the study and a scholar at the University of California-Berkeley.
It’s also possible that radon gets trapped inside tightly sealed modern buildings, she said.
Casey said the approximately 7,000 unconventional gas wells that were drilled in Pennsylvania between 2005 and 2013, as reported by the DEP, may have facilitated the elevated radon levels.
“By drilling 7,000 holes in the ground, the fracking industry may have changed the geology and created new pathways for radon to rise to the surface,” she said, in a statement.
Kevin Stewart, Director of Environmental Health at the American Lung Association of the Mid-Atlantic, said the group supports policies to protect air and water during natural gas production, but he questioned the study’s assertion that higher radon levels could be traced to the start of the fracking boom.
Since the study reported that buildings using well water had a 21 percent higher radon concentration than those using municipal systems averaged over the whole study period – which began more than a decade before Pennsylvania’s fracking boom – it does not necessarily indicate a link between fracking and radon, Stewart said.
“These differences in the data were observed going back to the 1980s, long before the expansion of unconventional extraction,” he said.
Rob Jackson, a professor at Stanford University’s School of Earth, Energy and Environmental Sciences, and who was not involved in the study, said the Hopkins report presents enough evidence to justify additional radon sampling.
But some aspects of the study undermine its claim of a link between higher radon and gas development, he said, noting that radon levels start increasing well before unconventional drilling ramps up, and that the strongest rise is noted in the Reading area which has no gas wells.
“We’ll need more work to understand those trends,” he said.
Radon, which degrades from radium, is among the naturally occurring radioactive material that exists in the Marcellus Shale, and may be brought to the surface through oil and gas development.
The new study noted that Pennsylvania as a whole has some of the highest levels of indoor radon in the country, and that levels may be increased because of gas development.
“The development of unconventional natural gas in the Marcellus Shale in Pennsylvania has the potential to exacerbate several pathways for entry of radon into buildings,” the study said.