The recent analysis out of the Johns Hopkins Bloomberg School of Public Health also shows that indoor radon levels were higher in counties with more drilling. The study was published online Thursday in the journal Environmental Health Perspectives.
Even before drilling took off in Pennsylvania, which has some of the largest frackable oil-and-gas reserves in the nation, the state had a radon problem. According to the Environmental Protection Agency, Pennsylvania has one of the highest radon levels in the nation. That’s why researchers were interested in studying the state; for this investigation, they took advantage of a large state-run database of home radon test results dating back to the mid-1980s.
Radon is an odorless radioactive gas that can seep into homes after venting off of uranium-rich soil and bedrock, such as shale formations rich with natural gas. The radon can enter through cracks in basement floors and walls. Indoor radon exposure contributes to about 21,000 lung cancer deaths in the United States each year, according to the EPA. Radon is one of the top three causes of lung cancer in the country.
There has been increasing concern that local drilling could be yet another major source of radon in Pennsylvania. In fact, the state’s Department of Environmental Protection sponsored its own study, published in January, looking into whether drilling was increasing the risk of public and worker exposure to unhealthy levels of radioactive material, including radon. That study specifically tested for radon in the air around four drilling sites, as well as analyzed radon levels in 22 extracted natural gas examples. Neither analysis revealed high radon levels.
But the new study, examining indoor radon levels, suggests otherwise. Brian Schwartz, professor of environmental health sciences at Johns Hopkins and a study author, told InsideClimate News, “We found evidence there could be a link.”
“If we were looking for reassurances, we didn’t find it,” he said.
State environmental regulators plan to review the study in detail, according to DEP spokeswoman Susan Rickens.
“This is an important paper published in an important journal,” said David Brown, a public health toxicologist based in Pennsylvania. That’s because “it’s directly health related,” he said. Brown was not involved in the study.
The study identified ways fracking could contribute to radon levels, whether through air emissions from the drilling process or emissions produced by of uranium-rich drilling waste, but it didn’t provide definitive proof. The study didn’t actually pinpoint specific radon sources.
Schwartz and colleagues reviewed indoor radon levels from 762,725 buildings, mostly homes, across all of the state’s 67 counties for the years 1989-2013. They also looked at building characteristics, geology and drilling intensity, among other variables. Here’s what they found: Before 2004, or pre-drilling, all counties showed similarly high levels of radon variability and there were several likely sources, such as bedrock. But after 2004, areas of high drilling had a pronounced increase in radon levels compared to areas of low drilling.
Moreover, buildings within 12.5 miles of a drilled well had higher radon levels than buildings further away. Pennsylvania has fracked more than 7,000 gas wells in the last decade; the state is the No. 2 producer of natural gas after Texas.
Julie Weatherington-Rice, an adjunct assistant professor in agricultural engineering at Ohio State University with a background in geochemistry, called the Johns Hopkins report a “very interesting paper” and a novel study. One of her concerns, however, involves the 12.5-mile distance. “That’s pretty far away for gas to travel in any level of concentration, either through the air or the soil,” she said.
According to the study, some of the highest average levels in the state were observed in Reading Prong, a geologic formation in southeastern Pennsylvania. There’s no fracking there, according to Schwartz. But he said this finding wasn’t surprising because that area’s geology is known to have high uranium levels.
Schwartz acknowledged limitations to the analysis. For example, the study authors didn’t have information on some critical details about the buildings where the indoor radon data was collected, such as building year or whether those structures used natural gas for heating or cooking. The paper points out that the upward trend of radon levels since 2004 could be attributed to buildings being more efficient and better able to keep heat—and gases—inside.