A study by the Pennsylvania Department of Environmental Protection found the liquid runoff from Pennsylvania landfills that take solid oil and gas waste poses no “significant” threat to the public from radioactive materials found in that waste.
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The agency sampled leachate, a type of wastewater that comes from rainwater and runoff from landfills. It took samples from 49 landfills around the state.
The DEP said its samples of the wastewater were mostly below federal drinking water guidelines of 5 picocuries per liter, and that none of the results were over a much higher standard of 600 pCi/L established by the Nuclear Regulatory Commission, or NRC, for wastewater sent to treatment plants from federally-commissioned nuclear facilities like nuclear power plants.
“DEP did not identify any levels of radiation associated with the landfill radium leachate investigation that raised concern for environmental protection or public health and safety. No results were observed that would require landfill action or suggest changes to engineering or operational controls,” the report said.
“The takeaway here is that there is no risk to human health from radiation in landfill leachate,” said DEP Secretary Jessica Shirley, in a statement.
The oil and gas industry cheered the results. In an online statement, the Marcellus Shale Coalition, an industry group, said the results reinforced “the fact that Pennsylvania’s existing regulatory framework and waste management practices are effectively protecting public health while allowing responsible natural gas development.”
Scientists skeptical
Scientists who have studied radium in Pennsylvania’s oil and gas waste stream criticized the state’s study.
“I would say I’m underwhelmed,” said Dan Bain, associate professor of geology and environmental science at the University of Pittsburgh. “It’s kind of declaring victory, but I don’t think we know the whole story yet.”
Bain co-authored a recent study finding increased levels of radium in sediment downstream of municipal wastewater treatment plants that handled this type of leachate.
Bain said radium tends to accumulate on the surfaces of particles in the sediment at the bottom of waterways. The DEP did not look at these sediments in evaluating the safety of the radium levels in landfill leachate.
“It might be below this NRC level, but what happens when it’s discharged to a stream?” Bain said. Bain said there is a risk that the radium discharged into the environment will affect wildlife or drinking water. “We don’t have a clear idea of how fast or how high it will accumulate and what will touch that once it has accumulated.”
The dangers of radium have been well documented. According to the EPA, chronic exposure to high levels can result in an increased incidence of bone, liver and breast cancer.
“Radium emits damaging radiation when it decays that will destroy or damage genetic material,” Bain said. “If it knocks out something like a tumor suppression system, the genetic encoding for tumor suppression, it will lead to cancer.”
Nathaniel Warner, associate professor in civil and environmental engineering at Penn State, said that because the DEP used two methods to calculate radium levels, one of which is imprecise, the report hasn’t really added much to the overall understanding of the issue.
“Overall, I was left with what seemed like not much information from what was probably an expensive endeavor to collect all these samples and send them to the laboratory,” said Warner. Warner has previously found elevated levels of radium in freshwater mussels near a waste treatment facility that treated oil and gas wastewater. He said the lack of data from the streams where treated leachate is ultimately discharged is a hole in the data.
“The state didn’t collect, or didn’t appear to collect, a single sample of the water actually leaving either the sewage treatment plants or the leachate treatment plants of the facilities,” he said. “To conclude that there’s no risk seemed like a stretch because they didn’t test the sediment or the water at the discharge.”
A long-standing issue
The DEP review was undertaken after then-attorney general Josh Shapiro convened a grand jury to investigate the regulation of the fracking industry. The 2020 report issued by the grand jury found the state wasn’t doing enough to regulate the industry.
Hydraulic fracturing, or fracking, has helped Pennsylvania become the second biggest gas-producing state in the country, after Texas. But the process creates millions of tons a year of solid waste containing potentially toxic characteristics.
The waste includes rocks and other soil cut out of the ground in deep gas-producing shales, as well as pipe buildups and sludges created during production. The waste contains high levels of metals, salts and radioactive materials, like radium, that are naturally occurring in the Marcellus Shale.
The issue garnered public attention in 2019, when a Pittsburgh-area waste treatment plant sued to have a nearby landfill stop sending it leachate after the treatment plant found high amounts of oil and gas contaminants in the liquid waste.
Data collection changes
One aspect of the DEP’s report that the scientists took issue with was that the agency used two separate test methods to test for radium. The first method, gamma spectroscopy, is an imprecise but less expensive test. The DEP reported those results for radium levels between 308 and 540 picocuries per liter.
About halfway through its experiment, the DEP switched to radiochemistry. This type of testing, which is slower, costlier, and involves more extensive sample preparation but is more accurate, said DEP spokesman Neil Shader, in an emailed response to questions about the report.
Those numbers came in far lower, between 1.43 and 122.731 piccuries per liter, according to the report.
“DEP collected and analyzed at least one untreated leachate sample for total combined radium from each landfill using radiochemistry to verify that the gamma spectroscopy data definitively fell below the 600 pCi/L action level,” Shader said.
In the more accurate radiochemistry test, only 11 landfills had radium levels above the federal drinking water guidelines of 5 picocuries per liter. And of those 11, only four landfills had “reportedly” accepted oil and gas waste between 2015 and 2024.
“DEP found no correlation between radium levels above 5 pCi/L and the acceptance of oil and gas waste at the landfill,” the report said.
Warner said the lower numbers are probably more accurate, but doesn’t think the overall report tells the public much about what is happening with the radium in this waste stream.
“Yes, landfills appear to have leachate that is less than the legal limit for 600 picocuries per liter for leachates coming out of industrial discharges. But it wasn’t actually quantified,” he said.
“It’d be like… going to the dentist and asking, do I have any cavities? And the dentist saying, ‘Well, you have fewer than seven cavities.’ And then like, well, how many do I have and [the dentist] just saying, ‘Well, I don’t know.’”
“Could there be very little radioactivity entering the environment? Warner said. “Absolutely, but I don’t think the state can say that based on the sampling that they did.”
DEP says it consulted on the report with the Environmental Research and Education Foundation, a research organization supported by the waste industry, and the Pennsylvania Waste Industries Association “to determine if the research and methodology was appropriate.”
The agency says it will continue sampling leachate for one more year.
