Ten years ago, the Pennsylvania Department of Environmental Protection released a study on radioactivity in the oil and gas industry, motivated by concerns that increasing amounts of toxic fracking waste could pose a risk to the environment and public health. The study concluded, in part, that further research is needed, particularly regarding the impact on the landfills where this waste is disposed of.
The agency released a follow-up study Friday specifically looking at landfill leachate, a liquid byproduct that forms when rainwater passes through waste and picks up pollutants along the way.
“The important point here is that there is no risk to human health from radiation in landfill leachate,” DEP Secretary Jessica Shirley said in a press release. The DEP study analyzed samples from 49 landfills in Pennsylvania over a two-year period from 2021 to 2023. That includes 23 landfills that receive oil and gas waste, according to state records.
But environmental and policy experts warned that the study was too narrow to draw definitive conclusions about the potential long-term harm from leachate contaminated with such waste.
“This is an interim report,” said Daniel Bain, an associate professor of geology and environmental science at the University of Pittsburgh who studies oil and gas waste. “This is not, ‘We have considered the problem. It is not a problem.'” It is, ‘We have considered the problem.’ There seems to be no problem so far. ”
The snapshot of DEP obtained in this study does not preclude different outcomes in the future and provides little insight into cumulative environmental impacts, Bain said.
The study acknowledged that its determination that there was “no cause for concern at this time” was based on limited data. “It is important to recognize that more landfill leachate samples and radiochemical analyzes are needed to generate additional data to support these initial findings,” the study authors wrote in their conclusion.
David Allard, former director of DEP’s Office of Radiation Protection, who oversaw the 2016 study of oil and gas waste, said he was “not surprised” by the results. “That’s consistent with what they were seeing early on,” he said. “We are satisfied with the findings” that radioactivity from the leachate does not presently pose a threat to human health.
But DEP needs to conduct consistent long-term monitoring, Allard said. “Landfills change over time. In my opinion, they should be sampled at least once a year.”
In 2021, then-Gov. Tom Wolf announced that Pennsylvania’s landfills will be required to be regularly tested for radium. Gov. Josh Shapiro, who was attorney general at the time, supported Wolf’s decision at the time. DEP confirmed in December that this requirement had not been implemented and did not issue such a rule with a new report.
DEP found that samples from just 11 of the landfills exceeded U.S. Environmental Protection Agency standards for combined radium-226 and 228 in drinking water, and none exceeded the much higher annual average standard for radium set by the U.S. Nuclear Regulatory Commission for untreated wastewater from facilities licensed to use radioactive materials.
None of these numbers are ideal for evaluating exudates. “There’s really no standard for leachate,” Allard said.
DEP also found “no correlation” between samples that exceeded EPA standards and the landfills that accepted oil and gas waste, according to state records. But a 2025 Inside Climate News analysis found that some of those records are riddled with contradictions. There is a total discrepancy of about 1.4 million tons between the amount Pennsylvania oil and gas operators said they sent and the amount landfills said they received, with some landfills reporting even more oil and gas waste coming in. One possible explanation is waste flowing in from other states.
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Oil and gas operators reported generating approximately 8.8 million tons of solid waste between 2017 and 2024. Approximately 6.3 million tons of that amount was sent to landfills within the state.
Environmental groups in Pennsylvania have been concerned about the consequences of producing and disposing of massive amounts of oil and gas waste since the hydraulic fracturing boom began two decades ago. Oil and gas waste often contains radioactive materials and may also contain heavy metals and other toxic chemicals.
David Hess, a former DEP secretary who now heads the publication PA Environmental Digest, pointed to several past problems associated with radioactive fracking waste, from it being sent to public wastewater treatment plants that could not properly treat it to treatment facilities that needed to be decontaminated.
“Like many things in the shale gas industry, we are the guinea pigs and have to learn things the hard way,” he said.
Some studies have shown that some radioactivity from oil and gas waste is already entering the environment, for example, downstream of the point of release at facilities that process or receive the waste.
“They’re just acting like the end of the pipe is the end. They’re not thinking about what’s going to happen as things build up in the flow,” Bain said of the DEP investigation.
He warned that the nature of contaminants in oil and gas waste, and the total amount the state emits each year, means regulators will need to closely monitor radioactivity in the environment and in landfills for many years to come.
“We’ll be watching forever because we allowed that to happen,” he said.
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Kylie Bence
pennsylvania reporter
Kylie Bence covers climate change and the environment with a focus on Pennsylvania, politics, energy and public health. She reports on the impact of the hydraulic fracturing boom in Pennsylvania, the expansion of America’s plastics industry, and the intersection of climate change and culture. Her previous work has appeared in The New York Times, The Atlantic, Smithsonian Magazine, Believer, and Sierra Magazine, and she holds a master’s degree in journalism and creative writing from Columbia University. She is based in Pennsylvania.
