The Nuclear and Radiation Studies Board of the National Academies hosted the symposium on The Future of Low Dose Radiation Research in the United States on May 8 and 9, 2019, at the National Academies facilities in Washington, DC. The goal of the symposium was to provide an open forum for a national discussion on the need for a long-term strategy to guide a low dose radiation research program in the United States. The symposium was organized by a planning committee of six experts chaired by Dr. Joe Gray (Oregon Health & Science University) and featured a range of presentations on the topics listed in the Statement of Task (see Sidebar 1.1). The symposium also featured panel discussions with government representatives and representatives of various professional, scientific, and other organizations to trigger an exchange of viewpoints with audience participation. The symposium was part of the Gilbert W. Beebe Symposium Series (see Sidebar 1.2), used to promote discussions among scientists, federal staff, and other interested parties concerned with radiation health effects.
About 120 representatives of governmental and nongovernmental organizations, academia, and research institutes participated at the symposium, and a similar number viewed the live webcast remotely. During the symposium, the session moderators asked for the participants’ engagement through Slido,1 an online tool for moderating questions and polls.2
2 A small number of symposium participants engaged through Slido. Therefore, the responses to the polls described in this proceedings may not reflect the views of all of the participants or of the entire radiation protection and scientific community.
This Proceedings of a Symposium was prepared by rapporteur Ourania Kosti as a factual summary of what occurred at the symposium. The planning committee’s role was limited to planning and convening the symposium. The views contained in the proceedings are those of individual symposium participants and do not necessarily represent the views of all symposium participants, the planning committee, or the National Academies.
This proceedings is organized into six chapters:
- Chapter 1 (this chapter) provides background information on low dose radiation health effects and sets the stage for the need of a low dose radiation research program in the United States. Information summarized in this chapter was primarily provided by speakers of the plenary session of the symposium. (See Appendix A for the symposium agenda.)
- Chapter 2 describes the Department of Energy’s (DOE’s) previous low dose radiation research program (terminated in 2016), other low dose radiation research programs around the world, and the current effort to coordinate low dose radiation research globally. Information summarized in this chapter was provided by speakers of Session 1 of the symposium.
- Chapter 3 provides perspectives on the need for a low dose radiation research program in the United States. Information summarized in this chapter was provided by speakers of Session 2 of the symposium.
- Chapter 4 describes current directions of low dose radiation research and potential new directions. Information summarized in this chapter was provided by speakers of Sessions 3 and 4 of the symposium.
- Chapter 5 describes lessons to be learned from coordinated research in air pollution and large-scale biology initiatives. Information summarized in this chapter was provided by speakers of Session 5 of the symposium.
- Chapter 6 summarizes the symposium participants’ considerations for a low dose radiation research program in the United States. The opinions summarized in this chapter were expressed by symposium participants throughout the 2-day symposium.
Low dose radiation exposures, generally taken to mean a dose less than 100 millisieverts (mSv), arise from natural background and a number of manmade circumstances including routine operations of nuclear energy production, nuclear waste management, research activities, accidents, and medical diagnostic procedures. In the early 1980s, the estimated per capita annual radiation dose to the U.S. population was 3.6 mSv, and natural background radiation exposure, primarily from indoor radon, was the predominant source of exposure. By 2006, the estimated per capita annual radiation dose was 6.2 mSv, and the increase was attributed to the use of medical diagnostic procedures, particularly computed tomography (CT) (NCRP, 2009).3
Human health effects at low doses of radiation are expected to be small but the uncertainties associated with current best estimates of risks are considerable. Nevertheless, exposures at low doses are of primary interest for setting standards to protect individuals against the adverse effects of ionizing radiation. The main health effect associated with exposure to low doses of ionizing radiation is cancer. Non-cancer effects such as hereditary,
cardiovascular, and central nervous system effects are receiving more attention than they did previously, but the occurrence and possible mechanisms at low doses of radiation remain uncertain.
Regulatory agencies in the United States, such as the U.S. Nuclear Regulatory Commission, the Environmental Protection Agency, and DOE, aim to set appropriate levels of protection against the harmful effects of radiation. These agencies currently use a model that describes the radiation damage as being directly proportional to the dose; this is called the linear no-threshold (LNT) model. According to the LNT model, the risk is not zero, regardless of how small the dose is. This model is used to set radiation protection standards and operating policies such as the “as low as reasonably achievable” (ALARA) policy.
However, the shape of the dose–response curve below about 100 mSv has been strongly debated for some time. In addition to the LNT model (curve [a] in Figure 1.1), four other basic model options are considered plausible (but not equally so, based on current knowledge) to describe low dose radiation risks (Brenner et al., 2003; see Figure 1.1). Any of these divergences to the LNT model imply that the current radiation protection system either overestimates or underestimates risks at low doses. An expert committee that recently reviewed epidemiological studies on low dose radiation concluded that data support the continued use of the LNT model in radiation protection (NCRP, 2018).
Dr. Brenner argued that there are significant health, social, and economic consequences for both under- and overprotecting against radiation. He and others provided examples of how uncertainties regarding the appropriate level of protection are affecting decisions of national and global significance:
- Protective action guidelines during the 2011 Fukushima nuclear power plant accident were based on incomplete knowledge about radiation risks at low doses. The differing recommendations for evacuation during the accident issued by the United States and Japanese governments caused confusion and stress, and a number of people died because of the evacuation process. Also, many evacuees still remain displaced or have chosen not to return to areas that have been declared safe for habitation, citing radiation fears.
- The true health effects of the Fukushima nuclear power plant accident have not been assessed due to incomplete information about radiation risks at low doses. Dr. Brenner said that various attempts
- Cleanup activities at sites that were utilized for nuclear weapons production and testing in the United States are estimated to cost more than $377 billion and take longer than 50 years to complete. DOE has committed to cleaning these sites to below background radiation levels and this commitment is based on incomplete scientific understanding of risks at those levels.
- Planning for high-level radioactive waste disposal and constructing a deep geological repository is impeded by current requirements for protecting future generations from low dose radiation risks.
- A global move toward phasing out nuclear power is the result of concerns about the environmental and health consequences of nuclear power plant accidents and the lack of planning for long-term storage of high-level radioactive waste.
- Risks from radon exposure in homes are uncertain, and better estimates could provide support (or not) for reducing radon exposure by mitigation strategies.
to quantify health risks from the accident have reached different conclusions, ranging from no predicted future cancer deaths to hundreds of deaths attributed to the releases from the accident.
- Risks associated with medical procedures such as CT scans are not fully understood and therefore a balanced consideration of probable benefits and probable risks is not always possible.
Dr. Brenner and others said that resolving the low dose radiation uncertainties relies on a pipeline of next-generation radiation professionals to be trained in radiation research and policy. It is well recognized that the volume of radiation professionals in the United States and elsewhere is shrinking.
Research in low dose radiation in the United States lacks a strategic agenda to address critical scientific issues. In fact, currently in the United States there is no program that is principally dedicated to low dose radiation research.
DOE’s Low Dose Radiation Research Program funded experimental research on cellular and molecular responses to low dose radiation starting in 1999 and was terminated in 2016 after ramping down funding over several years. Several other federal agencies within the United States have programs that support research on low dose radiation. However, these programs are not explicitly low dose radiation research programs. In addition, they are set to respond to the federal agencies’ specific missions and not to an overarching strategic plan.
A recent report from the Government Accountability Office (GAO) found that seven federal agencies dedicated about $210 million for research on the health effects of low dose radiation in fiscal years 2012 to 2016 (GAO, 2017). Mr. John Neumann (GAO) noted that during that period, federal agencies would collaborate on low dose radiation research projects and co-fund them; however, these collaborations did not have a formal mechanism to prioritize research, minimize duplication, and make sure resources were used efficiently. He added that about half of the funds were provided by DOE and therefore the total funds declined sharply as a result of the termination of the DOE program. The GAO report (2017) recommended that DOE lead the development of a mechanism for interagency collaboration for research on the health effects of low dose radiation. DOE did not concur with the recommendation.
Over the past 5 years, Congress has attempted to re-establish a low dose radiation research program in the United States. Despite the bipartisan interest, negotiations within the government have not yet resulted in its establishment.
In 2014, Congress introduced the Low-Dose Radiation Research Act (H.R.5544). The Act directed DOE to sponsor an 18-month National Academies study to assess the current status of and develop a long-term strategy for low dose radiation research. The Act also directed that, upon completion of the study, the Secretary of Energy would deliver a 5-year research plan to Congress that responds to the study’s findings and recommendations and identifies and prioritizes research needs. The 2014 Act was re-introduced in 2015 (H.R.35) but was not supported by the entire Congress.
In December 2017, Congress re-introduced the Low-Dose Radiation Research Act (H.R.4675). The Act eliminated the request for the 18-month Academies study to provide advice to DOE on a long-term strategy for low dose radiation research and instead directed the department to deliver a 4-year research plan within 6 months of enactment of this Act. It also directed DOE to carry out a basic research program on low dose radiation.
The American Innovation and Competitiveness Act of 2017 directs the National Science and Technology Council (NSTC) of the Office of Science and Technology Policy to coordinate federal efforts related to radiation biology and formulate overall scientific goals for the future of low dose radiation research in the United States.4
In September 2018, the Department of Energy Research and Innovation Act (H.R.589/S.2503) was signed into law. The Act combined seven previously passed science bills to provide policy direction to DOE, including on nuclear energy research and development. Title III directs DOE to carry out a low dose radiation research program to enhance the scientific knowledge of, and reduce uncertainties associated with, the effects of exposure to low dose radiation to inform improved risk-management methods. In May 2019 the House Appropriations Committee approved up to $10 million in funding to establish a low dose radiation research program within DOE’s Office of Science. In September 2019 the Senate Appropriations Committee did not make a budget recommendation for the low dose research program.
4 A representative from the NSTC attended the symposium and later noted in an email communication with the rapporteur that the discussions at the symposium are used as input for the activities of the NSTC.