The yearlong, peer-reviewed study under Gov. Tom Corbett’s administration analyzed radioactivity levels in flowback water, treatment solids and drill cuttings. It also monitored the transportation, storage and disposal of drilling wastes.

“The study report is the culmination of a multi-year effort and represents what we believe to be the most comprehensive radiological study of the oil and gas industry ever conducted,” Vince Brisini, DEP Deputy Secretary for Waste, Air, Radiation and Remediation, said in a news release.

“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.”

Naturally occurring radioactive material is contained in rock formations and can be released through the drilling process in drill cuttings and flowback water. The DEP’s study also analyzed radon levels in natural gas, which it said posed “little potential” for exposure.

Although the study determined the risk of radiation exposure to the public is low, the study found there are “potential radiological environmental impacts from fluids” if they are spilled or leaked. The DEP suggested radium be added to the state’s spill protocol to ensure cleanups are adequately characterized.

The DEP also considered the “limited” risk of radiation exposure for walkers and cyclists using roads that were treated with brine from natural gas wells, but said further studies on the environmental impacts of brine should be conducted.