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Discussion Topic 4, Updated dose/risk factors and scenarios for assessing radiological and non-radiological risk.

2010 July 7

Since 40 CFR Part 192 was released in 1983, changes and updates have been made in the underlying science that supports radiation dose and risk assessments for this rule.

Important literature citations about some of these changes include—

  • International Commission on Radiological Protection, 2008. “Publication 103 Recommendations of the ICRP, Annals of the ICRP.” Volume 37, Issue 2-4, January 2008.
  • National Research Council, 2006. “Health Risks for Exposure to Low Levels of Ionizing Radiation; BEIR VII, Phase II.” Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation, Board on Radiation Effects Research, Division of Earth and Life Sciences.  National Academies Press. Washington, DC 20001.

EPA is reviewing the existing rule to evaluate—

  • potential impacts of changes in dose and risk assessment
  • additional exposure scenarios
  • use of different or updated computer risk models
  • models that include distribution of Tribal and environmental justice communities’ population and their usage of land and resources
  • impact of climate on exposure from facilities not located in the historic mining areas of the southwestern U.S.

We invite you to provide your thoughts on this topic.

Editor's Note: The opinions expressed in Greenversations are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

6 Responses leave one →
  1. Stanley J. Waligora Jr., CHP permalink
    July 22, 2010

    Another important report to consider is the EVALUATION OF GUIDELINES FOR EXPOSURES TO TECHNOLOGICALLY ENHANCED NATURALLY OCCURRING RADIOACTIVE MATERIALS, Board on Radiation Effects Research, National Research Council, National Academy of Sciences, 1999.

  2. David Miller permalink
    July 28, 2010

    Please include an economic analysis of your proposed action. Increasing regulations will result in a lower standard of living for all people, including children, in the affected area. Does the lower standard of living result in a more harmful health effects to the population than allowing the uranium processing facility? and the resulting higher standard of living because of the high paying employment offered?

  3. bcourter permalink*
    July 29, 2010

    Thanks for your recommendation! We have added the National Academy’s report, as well as EPA response to it, to the Library of Documents.

  4. bcourter permalink*
    July 29, 2010

    Thank you for your input. EPA has not yet decided to propose a revised regulation. We are at an early stage of the process and are still reviewing the existing regulations to determine if changes are necessary. If this review determines that the Agency should go forward with draft revisions to the regulations, we will prepare a detailed cost-benefit analysis that will examine the issues you raised. This cost-benefit analysis would be made available to the public for review and comment. If you have any additional information and references you might wish to provide to us on the economic topic you have brought up, we encourage you to send us an e-mail at Thanks again for participating in our review.

  5. Phil Egidi permalink
    September 23, 2010

    UMTRA and the implementing regulations were promulgated at a time of 500 mrem/y public dose limits. The 1983 EPA EIS estimated about 130 mrad/y at 5 pCi/g Ra-226 using default occupancy, etc. One has to really tweak the models to get 5 pCi/g Ra-226 under 100 mrem/y in a residential scenario (the West Valley memo rings a bell). Considering that the EPA limit on release of other rad sites is 15 mrem/y > background, it would appear that 5 pCi/g > background is no longer protective. The 15 pCi/g subsurface limit should be dumped because it is not health-based.

    The radon limit also should be revisited based on BEIR VI and other more recent work.

    EPA should consider BEIR VI, VII and FGR-13, and ICRP 103 in its review. Cancer morbidity as well as mortality, age-adjusted DCFs, etc found in FGR 13 point the way for EPA to update the UMTRA

    UMTRA does not have surface activity limits, which is difficult for those of us who work in the field. Not all contamination is in bulk soil or groundwater, contaminated piping from the old mills is still found often in CO, and we have to adopt other standards e.g., ANSI N13.12 to control surface contaminated residual radioactive material.

    There are no supplemental standards for Title II, which is a deficiency. If one can get an ACL for groundwater, why can’t we get them for soil that can’t be effectively remediated?
    If an area cannot meet the concentration-based limit, but can meet today’s dose- or risk-based limits, that should be protective.

    A concentration-based criteria should be derived (again) based on residential risk, and retained as the primary standard. Since that value will be near background for radium-226, EPA must also consider what can be measured at a reasonable cost. 3 pCi/g > background may be a starting point for discussion.

    Ingestion of Po-210 should be revisited since the fsub1 value changed so much in ICRP60 et seq.

    Since site-specific risk-based limits are derived based on scenario, the possibility exists (and has come to pass) that the site goes from recreational (very low residence time and high residual radioactivity) to occupational or residential use. The site is no longer protective under the new scenario, and it may go undetected. This can pose a real problem that can be avoided by applying a generic concentration-based standard under all scenarios. It will keep things simple, and not place such a reliance on institutional controls, which are not always durable.

    Endpoints other than cancer should be reviewed, including cardio-vascular insults. There has also been a recent paper describing elevated radon progeny levels in the brains of Parkinson’s and Alzheimer’s patients.

  6. bcourter permalink*
    October 25, 2010

    Your detailed thoughts on these matters are particularly useful, especially with respect to dose and risk assessment, scenarios, toxic impacts of the metals and other daughter products, updates in radiation protection science, and implementation aspects of the regulations. Recycling of radioactively contaminated materials from mills was an especially important issue when Congress wrote UMTRCA and we appreciate the comment on piping.

    We are reviewing changes in regulatory approaches and policy for regulatory agency implementation concerning the direct measurement of concentrations in addition to dose/risk levels, and appreciate your concern.

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