Correcting Some Misconceptions about EPA's Superfund Approach for Radiation Risk Assessment

The U.S. Environmental Protection Agency (EPA) Office of Superfund Remediation and Technology Innovation (OSRTI) has primary responsibility for implementing the remedial long-term (non-emergency) portion of a key U.S. law regulating cleanup: the Comprehensive Environmental Response, Compensation and Liability Act, CERCLA, nicknamed "Superfund." The Superfund program generally addresses radioactive contamination in a consistent manner as it addresses chemical contamination, except where there are technical differences between radionuclides and other chemicals. For example, cleanup levels for radioactive contamination at sites are generally expressed in terms of risk levels (e.g., 10^-4), rather than millirem or millisieverts, as a unit of measure. Although EPA and other US agencies have issued millirem-based regulations under other statutory authorities, under CERCLA EPA promulgated a risk range of 10^-4 to 10^-6 as a standard of protectiveness for all carcinogens including radionuclides. CERCLA guidance recommends the use of slope factors when estimating cancer risk from radioactive contaminants, rather than converting from millirem. Current slope factors are based on risk coefficients in Federal Guidance Report 13. The Superfund remedial program uses 10^-6 as a point of departure and establishes Preliminary Remediation Goals (PRGs) at 1 x 10^-6. PRGs not based on other environmental standards known as Applicable or Relevant and Appropriate Requirements (ARARs) are risk-based concentrations, derived from standardized equations combining exposure information assumptions with EPA toxicity data. The policy rationale and technical underpinnings for this risk management approach is often misunderstood by radiation professionals. This presentation will help clarify some of these misunderstandings by focusing on misstatements about the Superfund approach that the author has encountered from radiation professionals. Often, they are citing the wrong EPA documents or portions of documents incorrectly, or not reading sections of the correct Superfund guidance.

Stuart Walker, U.S. EPA Office of Superfund Remediation and Technology Innovation (walker.stuart@epa.gov)
Stuart Walker has been employed by U.S. EPA in Washington, DC since 1990 in either the Superfund program (the Office of Superfund Remediation and Technology Innovation) or the Office of Radiation and Indoor Air working on issues regarding the cleanup of contaminated sites. His primary area of responsibility includes serving as the Superfund program's national lead on issues regarding radioactively contaminated CERCLA sites. In this role, Stuart develops national policy for risk assessment including models, community involvement, compliance with Applicable or Relevant and Appropriate requirements (ARARs), establishing cleanup levels and management of radioactive contamination at CERCLA sites.

Moderator:

Jean Balent, U.S. EPA Technology Innovation and Field Services Division (balent.jean@epa.gov or 202-566-0832)
Ms Balent is on the staff of the EPA's Technology Innovation and Field Services Division where she has worked to collect and disseminate hazardous waste remediation and characterization information since 2003. Ms Balent manages the Clean Up Information Network website and actively supports online communication and collaboration resources available to EPA. She formerly worked with the US Army Corps of Engineers Environmental Engineering Division in the Buffalo District. Ms Balent was also a member of the SUNY-Buffalo Groundwater Research Group where she constructed and tested large scale models of groundwater flow. Ms Balent has also conducted research relating to the Great Lakes, environmental remediation, and brownfields re-development. She holds a Bachelor's degree in environmental engineering from SUNY-Buffalo and a Master's degree in Information Technology from AIU.

• Slide Presentation for Correcting Misconceptions about EPA's Superfund Approach for Radiation Risk Assessment (6.56MB/PDF)

Webinar Slides and References:

• Slide Presentation for Correcting Misconceptions about EPA's Superfund Approach for Radiation Risk Assessment (6.56MB/PDF)

Additional Resources:

• Background paper for January 31, 2024, CLUIN Webinar
• "Federal Guidance Report No. 13: Cancer Risk Coefficients for Environmental Exposure to Radionuclides"U.S. EPA Office of Air and Radiation. September 1999
• "The Presidential/Congressional Commission on Risk Assessment and Risk Management Final Report. Volume 1" 1997.
• "The Presidential/Congressional Commission on Risk Assessment and Risk Management Final Report. Volume 2" 1997.
• “Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring.” The National Academy of Science. 1999.
• "Commentary on Harmonizing Chemical and Radiation Risk-Reduction Strategies" EPA Science Advisory Board (SAB) Radiation Advisory Committee (RAC), 1992.
• "A Method for Estimating Radiation Risk from Total Effective Dose Equivalent (TEDE)" The Interagency Steering Committee on Radiation Standards (ISCORS). 2002.
• "Guidance on the Development, Evaluation, and Application of Environmental Models" US Environmental Protection Agency, EPA/100/K-09/003 | March 2009.
• "Soil Screening Guidance: User's Guide." U.S. EPA, EPA540/R-96/018, July 1996.
• "Soil Screening Guidance for Radionuclides: User's Guide." U.S. EPA, OSWER No. 9355.4-16A, October 2000.
• "Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions." U.S. EPA, OSWER Directive9355.0-30, April 22, 1991.
• “Soil Screening Guidance: Technical Background Document.” U.S. EPA, EPA/540/R-96/128
• "Soil Screening Guidance for Radionuclides: Technical Background Document."
• "Radiation Risk Assessment At CERCLA Sites: Q&A." U.S. EPA, EPA 540-R-012-13, May 2014.
• "Consolidated Decommissioning Guidance: Characterization, Survey, and Determination of Radiological Criteria." NRC. NUREG-1757, Volume 2, Revision 2. July 2022
• "Framework strategy for dealing with radioactive contamination arising from the circumstances surrounding the death of Alexander Litvinenko" City of Westminster, United Kingdom.
• "Sources, Effects, and Risks of Ionizing Radiation" United Nations Scientific Committee on the Effects of Atomic Radiation UNSCEAR 2012 Report to the General Assembly with Scientific Annexes.
• Executive Order (EO) 12866 "Regulatory Planning and Review", September 30, 1993
• E.O. 13563 "Improving Regulation and Regulatory Review", January 18, 2011

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 January 31, 2024: Correcting Some Misconceptions about EPA's Superfund Approach for Radiation Risk Assessment

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