Radon levels in houses near fracking sites in Pennsylvania are higher than in those in areas where there is no oil and gas drilling, according to a new study by Johns Hopkins University researchers.
The researchers cautioned that their findings don’t definitively tie hydraulic fracturing to higher levels of radon.
But they say they found a “statistically significant association” between a building’s proximity to a fracked well and to the amount of radon detected.
“The higher the gas production … the higher the basement radon levels,” said Brian Schwartz, one of the study’s authors and a professor of environmental-health sciences at Johns Hopkins.
Radon, an odorless, invisible gas, is the second-leading cause of lung cancer in the United States after smoking, according to the U.S. Environmental Protection Agency. The EPA estimates that about 21,000 people die each year from lung cancer caused by radon.
The Johns Hopkins researchers analyzed more than 860,000 radon measurements collected from 1989 to 2013 in Pennsylvania. They found that buildings in counties with high levels of oil and gas extraction had significantly higher readings of radon than those in areas where fracking didn’t occur.
There was no difference between counties prior to 2004, when Pennsylvania’s oil and gas boom began.
Schwartz said the researchers don’t know whether other factors might have caused the increases. He said more detailed study is needed.
However, the findings “do not provide reassurance” that fracking is not contributing to radon increases, he said.
Their findings will be published online today in the journal Environmental Health Perspectives.
The Hopkins researchers focused on Pennsylvania because the state’s Department of Environmental Protection has decades of radon data and fracking has become ubiquitous in parts of the state. Oil and gas companies drilled and fracked more than 7,000 wells in Pennsylvania from 2005 to 2013.
Hydraulic fracturing involves pumping millions of gallons of water, sand and chemicals deep underground to crack shale deposits and free trapped oil and gas.
Much of the fracking fluid returns to the surface after the process finishes, carrying with it naturally occurring radioactive materials from the shale. Those materials can include radium and uranium, which decay to form radon.
The researchers also focused on Pennsylvania, Schwartz said, because it has a history of radon issues.
So does Ohio, where more than half of its 88 counties — including those in central Ohio — have average radon levels that are higher than the highest allowable level recommended by the U.S. EPA.
Radon levels also are high in eastern Ohio, where the state’s fracking activity has been concentrated.
Ashok Kumar, chairman of the University of Toledo’s civil-engineering department and the lead scientist for the Ohio Radon Information System, said that it makes sense that radon would migrate into homes near fracking sites.
“When you are fracturing, this means there will be more cracks, so more surface area, more open area,” Kumar said. “So the radon can flow out from those areas.
“The process of decay of uranium will be the same — it doesn’t matter whether it is fracking or any other activity — but now there is more room for that radon to escape.”
A spokesman for the Ohio Department of Natural Resources, which regulates the oil and gas industry, said officials there hadn’t seen the report and couldn’t comment on it.
Nathan Johnson, an attorney for the Ohio Environmental Council, an advocacy group, said the Johns Hopkins findings are alarming.
“It looks like fracking has unearthed an unbargained for and serious cancer risk in peoples’ homes,” Johnson said. “Some things are meant to remain buried.”
The study, Schwartz said, should at least persuade people to have their houses tested for radon.
“Anybody who lives in radon areas should know what their household radon levels are,” he said. “ If they’re elevated, they need to know what to do to lower them.”