Does Marcellus shale pose a radioactivity risk?

Radioactivity is a special kind of energy that is given off when unstable atoms release particles from their nucleus.  Our natural surroundings, including the air, water, rocks, and even many foods contain various radioactive elements, producing a low level of background radioactivity. Our bodies can easily handle such low doses of radioactivity. However, exposure to levels of radioactivity much higher than background can harm our bodies, especially by causing cancer1.

Radiation through materials

Radioactivity has three different forms in nature, called alpha, beta and gamma2.  Alpha radiation occurs when heavy elements like uranium, thorium, or radium lose a particle consisting of two protons and two neutrons from their nucleus. Such particles travel only a few centimeters in air, and are stopped by a sheet of paper or even the outer layer of your skin1. However, when they are inhaled or ingested, they can cause cancers1,3. 

Beta radiation occurs when minute charged particles (electrons and positrons) are emitted from atoms that have unstable nuclei – such as strontium-90, carbon 14, and tritium (hydrogen 3). Beta radiation has more energy than alpha radiation, and can penetrate into deep layers of your skin, where it can cause damage. Substances emitting beta radiation, such as radium-228, can be harmful if inhaled or ingested1,2.

Finally, gamma radiation has much greater energy than alpha and beta radiation, and is often released when certain elements undergo nuclear transformation and release high amounts of energy. Because of its higher energy, gamma radiation causes much more damage to living systems than alpha or beta radiation1.

Some elements that occur naturally in the earth’s crust have radioactive forms, and release alpha, beta, and/or gamma radiation. Examples include uranium, radium, radon, iodine, thorium, and even potassium. Since they are found in nature, such elements are called naturally occurring radioactive material (NORM)3.

Buried rock throughout all of northeastern Pennsylvania tends to have higher levels of NORM than the soils we encounter at the surface. Activities that expose us to rock, such as highway rock cuts and coal mining, elevate our exposure to NORM3.  The highest exposure is typically caused by radon gas, which is naturally emitted from the soil. Radon gas can accumulate in poorly ventilated buildings, and should be vented when concentrations are found to be excessive4.

Marcellus shale deposits contains natural radioactivity due to the presence of a few elements. They include the elements uranium and thorium, and their radioactive decay products – notably radium-226. Moreover, radioactive varieties – called radioisotopes – of the element potassium also contribute to Marcellus Shale’s radioactivity5. 

Marcellus has particularly high levels of natural radioactivity compared to those of other shales,. It contains emissions that are 20 times higher than the typical background radiation due to high uranium content. In fact, because of this characteristic, drilling companies and geologists use radiation detection to identify the location of the Marcellus Shale deposit5.

Natural gas drilling in the Marcellus Shale can result in NORM being brought to the surface as rock cuttings from drilling operations, as well as flowback of hydraulic fracturing fluid.  Because gas companies are now recycling their fracing water multiple times, its resulting radioactivity may continue to increase with reuse2.

In theory, Marcellus shale development can release radioactivity into the environment in three ways. First, rock cuttings from drilling may be improperly disposed. Second, wastewater may be improperly treated and discharged into streams and rivers. Third, wastewater may be intentionally released into the environment – such as by spreading it on roads as deicing material. In each case, radioactivity can potentially harm plants and animals in natural ecosystems. Perhaps of greater concern, it can enter drinking water supplies – especially where communities withdraw their drinking water from rivers downstream of water treatment facilities that receive wastewater from Marcellus operations5.

There are conflicting reports concerning the danger posed by Marcellus Shale drillings. In Onondaga County, NY, where the shale is closest to the surface, radon gas concentrations in the basements of homes built atop Marcellus shale had levels of radon averaged almost 9 picocuries per liter (pCi/L)6. By comparison, the U.S. Environmental Protection Agency’s recommends that homeowners take action to reduce radon in the air when levels above 4 pCi/L are measured. The national average indoor radon level is 1.3 pCi/L6.

In contrast, reports from an independent certified health physicist in Chemung County, NY showed levels of radiation in Marcellus Shale drill cuttings coming from Pennsylvania Marcellus drilling operations to the Chemung County landfill were “well below” U.S. Environmental Protection Agency standards for radiation.  The report said that the material is less radioactive than the countertops in kitchens and soil in gardens7.

Studies of NORM levels in rock cuttings have brought mixed results. A study sampling drill cutting waste from three landfills in Southern New York found low levels of radionuclides that were concluded to not pose any environmental health problems8.  On the other hand, a report by Radioactive Waste Management Associates concluded that rock cuttings hold up to 20 percent of drilling fluid with concentrated radium are a hazard through disposal, as they are transported to landfills9.  Marcellus radiation levels may vary by region and even by drilling sites, showing that testing on every cutting batch before deposal is ideal10.

NORM has been found in the pipe scale, brine filtrates, and other sludges associated with drilling. These products should pose no environmental threat because federal regulations restrict their transport. Thanks to regulations by the United States Environmental Protection Agency (EPA) through the Resource Conservation and Recovery Act11, companies must comply with shipping container requirements, keep records on transported hazardous waste, and notify officials of any waste discharges.

A more significant controversy exists regarding the discharge of wastewaters. Before spring 2011, drilling companies in Pennsylvania brought their wastes to facilities that treated municipal waste throughout the state12.  A series of reports published by the New York Times in February 2011 highlighted concerns over that industry practice13. The series highlighted the fact that such facilities are ill-equipped to remove radioactivity from wastewater. Partially treated water from those plants entered into rivers. Therefore, any radioactivity entered the receiving rivers, posing a threat to downstream communities that withdrew water from the river, as well as to aquatic plants and animals that live downstream.

Measurements taken by the DEP in rivers throughout Pennsylvania found low levels of alpha and beta radiation, and radionuclides such as Radium 226 and 228. In March 2011, the Pennsylvania Department of Environmental Protection (DEP) released a report indicating that in-stream monitoring in several locations downstream from wastewater treatment facilities that accepted water from Marcellus Shale drilling showed no radiation above the background levels14. This water was tested before it entered intakes for public water suppliers, which are subject to further treatment.

The Federal Safe Drinking Water Act of 1974 (SDWA) established drinking water standards for radioactivity: 15 pCi/L for gross alpha radiation, 4 mrems for beta radiation, 5 pCi/L for combined radium 226/228, and 30 µg/L for uranium15.

Significantly, SDWA standards only pertain to public or private water supplies that serve more than 25 customers. Private well water systems are not subject to those standards.

Recognizing the hazards imposed by allowing companies to take their wastewater to treatment facilities that discharge into receiving streams, on April 16, 2011, the Secretary of the DEP requested energy companies to end that practice. In response, 97 percent of shale wastewater in the last half of 2011 was recycled, sent to deep-injection wells, or sent to a treatment plant that doesn't discharge into waterways16. compiled DEP data to show disposal methods and amounts for Marcellus Shale waste in Pennsylvania from July to December 2011. It showed that disposal of waste at sewage treatment plant had mostly ceased, and that two-thirds of liquid waste is sent to brine and industrial waste facilities17.

Radioactivity may also be released into the environment when salty flowback (brine) is spread onto roads18. In Pennsylvania, the DEP permits brines to be spread on roads during wintertime de-icing purposes, and to suppress dust on unpaved roads during the summer.  The use of gas brines for de-icing is allowed through Residual Waste Beneficial Use General Permit WMGR06419.  That general permit was developed in 2000 when shallow production wells were the primary source of natural gas brines19.  Brines from such wells are low in radioactivity, and thus their use does not pose a threat - at least in terms of radioactivitity.  The use of gas brines for dust suppression is allowed by the approval of a  plan by the PADEP, following the guidelines presented in a DEP guidance document20.

Conceivably, using brine for de-icing and dust control can introduce radioactivity into the environment if: (1) the brine originates from shale drilling operations, and (2) runoff makes its way into surface or groundwater.  DEP guidance regarding the use of brines for dust suppression explicitly prohibits the use of brine produced from shale formations, and requires that the brine is applied in a manner that prevents it from running off into ditches and natural surface water, and infiltrating into groundwater20.  Conversely General Permit WMGR064 that covers winter de-icing operations does not specifically exclude the use of brines from shale gas operations19.  But the PADEP plans to introduce policies to create such an exclusion before the 2012 / 2013 winter season21.  If those policies are enacted and enforced, radioactivity from Marcellus shale would not find their way into the environment via the road application of brines.

Because Marcellus shale has high levels of radioactivity, it is important to ensure that waste materials from drilling operations are properly handled through the disposal of rock cuttings and the usage of wastewater. While many regulations are in place, more analysis should be conducted to ensure that these rules are being followed by gas companies.  Studies should also be conducted to determine whether these regulations are stringent enough to minimize the risk to environmental and human health during drilling waste disposal practices. 


1 HPS. 2011. Radiation basics. Health Physics Society.

2 EPA. 2012. Basic Information about the Radionuclides Rule. United States Environmental Protection Agency.

3 Interstate Oil and Gas Compact Commission. What is NORM? NORM Technology Connection.

4 EPA. July 2005. A Regulators’ Guide to the Management of Radioactive Residuals from Drinking Water Treatment Technologies. United States Environmental Protection Agency.

5 Marvin Resnikoff, Ph.D., Ekaterina Alexandrova, Jackie Travers. May 19, 2010. Radioactivity in Marcellus Shale. Radioactive Waste Management Associates.

6 Lisa Sumi. May 2008. Shale Gas: Focus on the Marcellus Shale. Oil & Gas Accountability Project/Earthworks.

7 Elmira Star-Gazette. April 11. Radiation Testing Shows Marcellus Shale Drill Cuttings are Safe for Chemung County, NY Landfill. Marcellus Drilling News.

8 CoPhysics. April 2010. Marcellus Shale Drilling Cuttings. CoPhysics Corporation.

9 Resnikoff, Marvin; Alexandrova, Ekaterina; Travers, Jackie. May 19, 2010. Radioactivity in Marcellus Shale. Radioactive Waste Management Associates.

10 Mantius, Peter. May 10, 2012. New York state dismisses radiation threat from gas drilling cuttings. DC Bureau.

11 EPA. April 3. 2012. Hazardous Waste Regulations. U.S. Environmental Protection Agency.

12 Kelso, Matthew. February 22, 2012. Updated Pennysylvania Marcellus Shale Waste Information. FracTracker.

13 Urbina, Ian. February 26, 2011. Regulation Lax as Gas Wells’ Tainted Water Hits Rivers. The New York Times.

14 DEP. March 7, 2011. DEP Announces Testing for Radioactivity of River Water Downstream of Marcellus Water Treatment Plants Shows Water Is Safe. Pennsylvania Department of Environmental Protection.

15 EPA. March 6, 2012. Radionuclides in Drinking Water. United States Environmental Protection Agency.

16 Associated Press. February 17, 2012. Marcellus Shale gas drillers recycling more waste. The Times-Tribune.

17 Kelso, Matthew. March 14, 2012. Where does the waste from PA’s Marcellus wells go? FracTracker.

18 Bamberger, M. & R.E. Oswald. 2012.  Impacts of gas drilling on human and animal health.  New Solutions 22: 51-77.

19 DEP. Special Conditions General Permit WMGR064. Department of Environmental Protection.

20 DEP. Roadspreading of Brine for Dust Control and Road Stabilization. April 2009. Department of Environmental Protection.

21 Scott Walters, DEP.  Personal communication on 3 July 2012.

Authors: Courtney Sperger, Kirstin Cook, Kenneth Klemow, Ph.D. ---- Posted: 1 August 2012 ---- Version: Revision 2

Suggested citation style: Sperger, C., K. Cook, and K. Klemow. 2012. Does Marcellus Shale pose a radioactivity risk? Institute for Energy and Environmental Research of Northeastern Pennsylvania Clearinghouse website. Posted 1 August 2012.