The Associated Press

Pennsylvania state environmental regulators released a study Thursday on radiation levels in oil and gas industry wastewater and byproducts that they say shows little potential for direct radiation exposure to workers and the public. But it recommends a follow-up study to determine whether radiation can build up in the environment.

The 200-page study began in 2013 after questions arose about the radioactivity in the huge volumes of wastewater and solid waste coming out of the ground in Pennsylvania's natural gas drilling boom.

State officials had said drilling waste had triggered radiation monitors at landfills but cautioned that very low levels of naturally occurring radioactive materials were found in the drilling waste.

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