The report follows a recent study by Duke University which stoked such fears, with geochemists reportedly finding “dangerous levels” of radioactivity and salinity at a fraccing disposal site near Blacklick Creek, which feeds into water sources for Pittsburgh and other western Pennsylvania cities.

While the DEP’s TENORM study – which analysed the naturally occurring levels of radioactivity associated with oil and natural gas development in Pennsylvania – outlined recommendations for further study, it concluded there was little potential for harm to workers or the public from radiation exposure due to oil and gas development.

DEP deputy secretary for waste, air, radiation and remediation Vince Brisini said the report was the culmination of a multi-year effort and represented what the DEP believed to be the most comprehensive radiological study of the oil and gas industry ever conducted.

“While the recommendations for future actions contained in the report call for additional studies and efforts, we now have data to inform the management of natural gas resources and resultant wastes for environmental and health protection,” he said.

The DEP began studying radioactivity levels in flow back waters, treatment solids and drill cuttings, as well as transportation, storage and disposal of drilling wastes, in January 2013 at the direction of Governor Tom Corbett.

This included a study of radon levels in natural gas to ensure that public health and the environment continued to be protected.

The peer-reviewed study concluded that there was “little or limited potential” for radiation exposure to the public and workers from the development, completion, production, transmission, processing, storage and end use of natural gas.

“There are, however, potential radiological environmental impacts from fluids if spilled,” the DEP said.

It recommended that radium should be added to the Pennsylvania spill protocol to ensure clean-ups were adequately characterised. There were also site-specific circumstances and situations where the use of personal protective equipment by workers or other controls should be evaluated, the study said.

While the report also concluded there was little potential for radiation exposure to workers and the public at facilities that treat oil and gas wastes, it warned that there were potential radiological environmental impacts that should be studied at all facilities in Pennsylvania that treat wastes to determine if any areas required remediation.

“If elevated radiological impacts are found, the development of radiological discharge limitations and spill policies should be considered,” the report stated.

“There is little potential for radiation exposure to the public and workers from landfills receiving waste from the oil and gas industry.

“However, filter cake from facilities treating wastes could have a radiological environmental impact if spilled, and there is also a potential long-term disposal issue. TENORM disposal protocols should be reviewed to ensure the safety of long-term disposal of waste containing TENORM.”

While limited potential was found for radiation exposure to recreationists using roads treated with brine from conventional natural gas wells, the report recommended further study of radiological environmental impacts from the use of brine from the oil and gas industry for dust suppression and road stabilisation should be conducted.

The Duke University study found that radiation was detected far above regulated levels even after waste water was treated at the plant to remove dangerous chemicals.

One of the primary authors of the Duke study, Avner Vengosh, professor of geochemistry and water quality at Duke University’s Nicholas School of the Environment, said the treated water had radium levels 200 times greater than control water from the area.

The team also found high levels of bromide in the water, which was particularly alarming as drinking water plants use chlorine and ozone to turn river water into drinking water. When those chemicals react with bromide, they produce highly toxic byproducts.

While Vengosh conceded that was yet to happen, he said it was a “dangerous possibility”