The U.S. Dept
“„The New York State Department of Health has identified Radium-226 as a radionuclide of particular concern in the Marcellus Shale formation deep beneath the Appalachian Mountains.
“„In hydraulic fracturing operations, drillers force water and a mixture of chemicals into wells to shatter the shale and free natural gas.
“„The brine that returns to the surface has been found to contain up to 16,000 picoCuries per liter of radium-226 (pdf). The discharge limit in effluent for Radium 226 is 60 pCi/L, and the EPA’s drinking water standard is 5 pCi/L.
“„Uranium and Radon-222 have also been found in water returning to the surface from deep shale wells.