Representatives of several government, professional, scientific, and other organizations with radiation research and radiation protection responsibilities were invited to participate in panel discussions and provide perspectives on a potential low dose radiation research program in the United States. Dr. Jim Brink (Harvard Medical School), who moderated the discussions, solicited brief responses from panel participants on the following three questions:
- Why is your agency/organization concerned with low dose radiation issues?
- What are the uncertainties related to low dose radiation issues that your agency/organization is facing and how do they affect its operations?
- What additional information could enlighten your agency’s/ organization’s decision-making process in radiation protection?
The panelists’ perspectives are summarized in the following sections.
Government representatives from different agencies have opportunities to meet and discuss topics of common interest,1 but they confirmed that the future of low dose radiation research in the United States has not been addressed during these interagency meetings. The symposium brought together government representatives of 10 agencies/offices (see Figure 3.1) to exchange views on the future of the low dose radiation research program in the United States.
Dr. Isaf Al-Nabulsi noted that one of DOE’s highest priorities is the protection of workers, the public, and the environment. The department is responsible for establishing radiation protection standards and also has the mandated responsibility to undertake research on the health effects of radiation exposure. The Office of Environment, Health, Safety, & Security within DOE supports domestic and international occupational epidemiological studies, health studies of workers and members of the public exposed to radiation from nuclear weapons production activities in the former Soviet Union, and the studies of the atomic bombing survivors conducted at the Radiation Effects Research Station (RERF) in Hiroshima and Nagasaki. (See Section 4.1.1 for more information on RERF.)
Dr. Al-Nabulsi stated that a decision on whether a low dose radiation research program needs to be established depends on the answers to questions such as the following: Is understanding of low dose radiation health effects critically important for federal missions? Is enough new information available that merits a re-examination of regulatory standards? If not, what additional information is needed?
She said that answers to low dose radiation questions can be provided by integrating epidemiological and radiation biology studies and noted that the National Council on Radiation Protection and Measurements’ (NCRP’s) scientific committee on Approaches for Integrating Radiation Biology and Epidemiology for Enhancing Low Dose Risk Assessment is exploring how this integration can be achieved. She also showed her support for using a low dose radiation research program to train the next generation
1 Two interagency meetings were mentioned at the symposium: (1) the Interagency Steering Committee on Radiation Standards, which provides an opportunity for agencies with radiation protection responsibilities to inform each other about issues and progress related to standard development and other topics, and (2) the Federal Radiological Preparedness Coordinating Committee, which provides an opportunity for the emergency preparedness and response community to provide assistance to the Federal Emergency Management Agency on policy direction for the program.
of experts in radiation biology, dosimetry, radiation epidemiology, molecular epidemiology, and risk communication.
Dr. Al-Nabulsi did not comment on a participant’s question about the current status of the DOE low dose radiation research program within the Office of Science. Representatives of that DOE office did not participate at the symposium.
Mr. Mike Boyd noted that radiation protection activities occur across various program offices at EPA. For example, the Drinking Water Office is responsible for setting maximum contaminant levels in water; the Superfund Program prepares the implementation of cleanup standards for Superfund sites; and the Center for Science and Technology within the Office of Radiation and Indoor Air/Radiation Protection Division develops dose and cancer risk coefficients that are used across the federal government, states, and the private sector to standardize risk assessment for radiogenic cancers.
EPA also has responsibility under the Atomic Energy Act for setting generally applicable standards for radioactivity in the environment. These
standards limit exposures to members of the public to a few millisieverts annually. Because risks at these very low doses are not experimentally known, EPA relies on the linear no-threshold (LNT) model to estimate the risks. Mr. Boyd acknowledged that there are a lot of uncertainties related to the use of the LNT model and that this model does not account for several factors, such as individual sensitivity, sex, age, and lifestyle factors.
Mr. Boyd added that new information that can improve the dose-related risk estimates would help EPA set more appropriate standards for radiation protection. In his view, research to better understand biological phenomena such as bystander effects, genomic instability, apoptosis, and their implications on current risk estimates is also warranted. In light of proposals to discontinue use of the LNT model in radiation protection and to adopt alternative models such as a radiation dose threshold model, Mr. Boyd expressed an interest in a comprehensive analysis of the policy implications of such a change.
Dr. Armin Ansari said that CDC’s mission is to promote public health. One of its responsibilities is to prepare the nation for an effective radiological and nuclear response. To achieve that, it uses the best available consensus science to inform and advise public health decision makers and members of the public. CDC also convenes meetings to bring together experts from a variety of scientific, medical, and public health disciplines to discuss decision making and communication issues related to radiological and nuclear incidents.
In March 2019, CDC sponsored the National Academies workshop Challenges in Initiating and Conducting Long-Term Health Monitoring of Populations Following Nuclear and Radiological Incidents in the United States (NASEM, 2019). A key theme of the discussions during that workshop was the implication of low dose radiation uncertainties on planning for long-term health monitoring following an incident that has affected a large percentage of the population.
Captain John Gilstad said that research in low dose radiation health effects has military relevance because of potential occupational exposures during operations in contaminated environments, involvement of the military in remediation of contaminated sites, and participation of atomic veterans in compensation programs.
DoD’s experience with the Fukushima nuclear power plant accident showed that the military is not sufficiently prepared to operate in a low dose
radiation environment nor is it capable of incorporating the uncertainties of low dose radiation risks into decision making. For example, after-action analyses of Operation Tomodachi2 identified a lack of consistent guidelines to translate detectable radionuclide levels to protective actions and a lack of preparation to implement ALARA decision making within an evolving emergency (U.S. Army Peacekeeping and Stability Operations Institute, 2013).
Captain Gilstad highlighted a few low dose radiation research areas of potential interest to DoD:
- Mitigating risks from low dose radiation,
- Prediction of radiation-induced cancers,
- Target therapy for radiation-induced cancers, and
- Psychological impacts of operating in a radiation environment on the troops and the commanders.
Dr. Mike Noska noted that the radiation protection mission of FDA encompasses several areas of radiation uses, including the safety and efficacy of radiopharmaceuticals for diagnosis and treatment of disease, performance of electronic products and medical devices that emit radiation, quality assurance standards for mammography, guidance on limiting exposures to radiation following radiological and nuclear emergencies, and guidance for development of medical countermeasures for treating and mitigating the effects of radiation exposure following nuclear or radiological incidents.
FDA regulates medical devices intended for human use and radiation-emitting electronic products. Although it does not have the authority to regulate patient doses, the agency promotes patient safety through the principles of justification and optimization. It also supports the use of diagnostic reference levels for optimizing doses and initiatives, such as Image Gently3 and Image Wisely, to encourage clinicians to make the best decisions possible to conduct quality studies at the lowest radiation dose possible.
FDA conducts research that supports the agency’s regulatory review process, for example, in areas of phantom development, dose assessment
2 Operation Tomodachi provided disaster relief to Japan following the 2011 Tōhoku earthquake and tsunami.
3 The Image Gently Alliance was formed in 2007 by a group of pediatric radiology volunteers and aims to improve safe and effective imaging care of children worldwide and to raise awareness of the opportunities to lower radiation dose in the imaging of children.
methods, and image analysis algorithms. Dr. Noska noted that FDA does not conduct research in low dose radiation. However, he identified two research topics of interest to FDA that relate to low dose radiation: (1) biodistribution of radionuclides to inform radiopharmaceutical development and normal tissue effects, and (2) risk communication in the medical setting.
Dr. Jeri Anderson said that NIOSH’s mission is to reduce work-related illness and injury and to promote safety and health in the workplace. Two divisions within NIOSH conduct work on radiation health effects: the Division of Compensation Analysis and Support, which is responsible for reconstructing doses for certain workers who are exposed during their work in the U.S. nuclear industry and may be eligible for compensation, and the Division of Field Studies and Engineering, which conducts occupational radiation epidemiology research. A special interest of that division is to improve exposure assessment methods.
Dr. Anderson identified three research focus areas of interest to NIOSH that relate to this topic:
- To improve current limitations of occupational epidemiology studies such as selection bias, misclassification of exposure, or misclassification of health outcomes and confounding;
- To understand the mechanisms and pathogenesis of disease outcomes in the occupationally exposed populations; and
- To understand the interaction between radiation and other exposures such as chemical and physical agents.
Dr. Steve Blattnig noted that NASA’s primary interest in radiation research is to mitigate the risk to astronauts’ health from space radiation. The types of health effects linked to space radiation are cancer, cardiovascular disease, and possibly central nervous system damage.4 NASA supports three space radiation research programs:
4 Although not explicitly discussed at the symposium, it is recognized that the risk to astronauts’ health may be influenced by other spaceflight factors such as microgravity, nutrition-related factors, and psychological and physiological stress. NCRP examined radiation exposures in space and the potential of central nervous system effects (NCRP, 2019b).
- The Space Biology Program, which examines how astronauts, plants, and animals regulate and sustain their growth in space;
- The Space Station Research and Technology Program, which conducts research on a large array of different experiments from biology and biotechnology to human health research relevant to exploration missions; and
- The Human Research Program, which aims to investigate and mitigate the risks to astronauts’ health and performance in support of exploration missions. A main focus of the program is on mitigating radiation risk and possibly developing biological or medical countermeasures.
In space, astronauts are exposed to radiation that is qualitatively5 different from terrestrial radiation and the doses, particularly over an astronaut’s career, tend to be within the moderate dose region. To help put this into perspective, Dr. Blattnig said that the dose received in space over an astronaut’s career at the International Space Station is within hundreds of millisieverts. However, a possible future mission to Mars can expose astronauts to 1 sievert (Sv). Still, NASA relies on findings from non-space radiation research, including low dose radiation research, to estimate risks to the astronauts and to set protection standards that are based on individual lifetime risk projections.
Dr. Blattnig recognized that the transfer and extrapolation of risks from non-space radiation studies introduces large uncertainties, and experts have questioned whether it is even appropriate. One topic of particular concern to NASA is the finding from the atomic bombing survivor studies that risk of radiation-induced lung cancer is greater for women than for men; this finding limits the time women can spend in space. NCRP has assembled a committee to assess the risk of radiation-induced lung cancer by examining findings from other exposed populations and experimental studies.
Dr. Blattnig recognized that there is considerable overlap of the areas of interest between low dose radiation research and radiation research at NASA. Therefore, as was the case in the past, coordinated efforts between NASA’s research programs and a potential new low dose radiation program could help advance knowledge on radiation health effects. He identified a couple of focus areas of a low dose radiation research program that could also help advance NASA’s research in space radiation effects: (1) experimental system development for low dose radiation research, and (2)
5 Dr. Blattnig described three different types of radiation sources in space: galactic cosmic rays, solar particle events, and radiation belts. These types of radiation sources have physical characteristics that are distinct from terrestrial sources of radiation such as X-rays and gamma-rays.
computational model development to mathematically represent physiological systems and integrate multiple experimental measures.
The USNRC’s mission is to regulate the nation’s civilian use of byproduct, source, and special nuclear materials and to provide reasonable assurance of adequate protection of public health and safety, and to the environment. To accomplish its mission, the USNRC licenses and regulates commercial nuclear power plants (including their decommissioning) and other uses of nuclear materials, such as in nuclear medicine. The USNRC also regulates storage and disposal of all commercially generated nuclear wastes. The USNRC partners with the states and relinquishes authority if they sign an agreement with the agency.
Dr. Terry Brock noted that the USNRC has funded studies on low dose radiation to inform the adequacy of radiation protection regulations for the general public and occupational workers. Two of these studies were discussed at the symposium: the Million Worker Study (see Section 4.1.2 for more information) and the Analysis of Cancer Risks in Populations Near Nuclear Facilities (NRC, 2012, 2014).6
Dr. Brock did not discuss his views on how a low dose radiation research program can help the USNRC improve how it regulates commercial nuclear power plants or carry out other activities. Instead, he noted that regulations are informed by science but there are several other factors that need to be considered in decision making. He added that a suggested change in one regulation needs to be viewed in the context of the entire radiation protection system.
DHS is charged with domestic security and facilitation of lawful customs and exchange. Dr. Andy Scott said that a main responsibility of DHS related to low dose radiation is to inform risk management and decision making following environmental radiation exposure, including transport and fate of radiation in the environment, particularly with regard to reoccupation and resumption of operations.
Dr. Scott identified four areas of low dose radiation research of interest to DHS:
6 The USNRC discontinued the study in 2015, citing the need for a significant amount of time and resources to carry out the study as the reason.
- Developing tools and methods to inform decision making in a timely manner,
- Enhancing understanding of radiation risk relative to other risks to support holistic risk management,
- Increasing sensitivities and advanced signal-to-noise processing used by the Countering Weapons of Mass Destruction Office, and
- Developing tools and methods for more effective and timely risk communication.
CRCPD is a nongovernmental professional organization of state representatives dedicated to radiation protection. Its mission is to promote consistency in addressing and resolving radiation protection issues, to encourage high standards of quality and radiation protection programs, and to provide leadership in radiation safety and education.
Ms. Jenny Goodman said that, to fulfill this mission, CRCPD relies on organizations such as the National Academies, NCRP, and EPA for findings, advice, and guidance for setting radiation standards. She identified the following areas of low dose radiation research of interest to CRCPD:
- Risk assessment and uncertainty analysis,
- Risk communication and communication of uncertainties,
- Individual susceptibility to risk and how this can be incorporated into regulations, and
- Biomarkers of radiation-induced disease.
Representatives of six scientific, professional, and other organizations (see Figure 3.2) noted their support for a low dose radiation research program and indicated their intent to be users (NCRP, American Society for Radiation Oncology [ASTRO]), advocates (Health Physics Society [HPS], American Nuclear Society [ANS]), collaborators (Electric Power Research Institute [EPRI], International Commission on Radiological Protection [ICRP]), or contributors (American Association of Physicists in Medicine [AAPM]) to the research conducted within the program. Their comments are summarized in the following sections.
NCRP is a congressionally chartered, nonprofit organization whose mission is to support radiation protection in the United States. Dr. Kathy Held stated that NCRP sees an urgent need for a low dose radiation research program because it will be a source for new, updated, and high-quality information that will inform the council’s future work. She listed a number of NCRP publications, already released or in preparation, that address low dose radiation issues:
- Commentary No. 27, Implications of Recent Epidemiologic Studies for the Linear-Nonthreshold Model and Radiation Protection (NCRP, 2018);
- A report on medical doses to patients in the United States (NCRP, 2019a) which provides an update to NCRP Report No. 160, Ionizing Radiation Exposure of the Population of the United States (NCRP, 2009); and
- A report on approaches for integrating radiation biology and epidemiology for enhancing low dose risk assessment. The report will include a discussion of the appropriateness of the adverse outcome pathway methodology used to evaluate the biological and toxicological effects of chemicals as a methodology to provide a framework for the assessment of radiation effects. This report is expected to be released in 2020.
NCRP is interested in maintaining a radiation workforce and has sponsored activities around the theme “Where are the radiation professionals?” to assist the radiation community with addressing the decline in radiation professionals and potential national crisis. NCRP also leads the Million Worker Study (see Section 4.1.2 for more information).
Dr. Nolan Hertel described HPS as “the society of radiation safety professionals.” He noted that among the society’s members there is a range of opinions about the appropriateness of the LNT model as the basis of radiation protection standards but there is a general agreement that there are uncertainties related to risks in doses below 100 milligray (mGy).
HPS invests in informing the public on issues related to radiation protection and has established an “Ask the Experts” webpage where more than 13,000 questions have been submitted and answered by members of the society. HPS also connects with government agencies and Congress to discuss topics of common interest. Establishing a low dose radiation research program has been a priority topic over the past year and HPS has been advocating for funding for the program.
ANS is a professional organization with about 10,000 members around the world who share an interest in promoting nuclear power. Dr. Alan Waltar expressed the society’s support in re-establishing a low dose radiation research program with the goal to dispute use of the LNT model in radiation protection and provide the scientific basis for supporting a threshold model.
He argued that current radiation protection standards for cleanup are “unreasonably conservative” and suggested that even minor changes toward relaxing them can result in billions of dollars in savings. He also argued that
current radiation protection standards are an impediment to several other nuclear or radiological activities, including planning for high-level radioactive waste disposal and constructing a deep geological repository, taking appropriate protective actions during a nuclear or radiological incident, and making decisions to reoccupy or use mildly contaminated areas.
EPRI is a member organization that conducts research and development related to the generation and use of electricity. Dr. Don Cool said that EPRI’s Radiation Safety Program conducts research to enhance current understanding of radiation risks that are typical of those received from routine operations of power plants, and to improve communication about those risks.
EPRI supports global collaboration and coordination to help answer questions of low dose and dose rate radiation health effects. In 2016, it established the International Dose Effect Alliance to organize workshops that bring together researchers from around the world to discuss research agendas, programs, and priorities in low dose radiation research.
Dr. Cool highlighted the need for open sharing of research results and analyses in low dose radiation research. In his view, the expanding collection and sharing of data together with technological advances in artificial intelligence and machine learning have the potential to revolutionize the field of low dose radiation. He was in favor of a multidisciplinary approach to low dose radiation research that engages experts in chemical toxicity and medical research and incorporates data from those disciplines in the big data analytics.
ICRP provides recommendations and guidance on all aspects of radiation protection, which help set radiation protection standards worldwide. The mandate for ICRP Committee 3 is to provide guidance on radiation protection from medical diagnosis, therapy, and biomedical research.
Dr. Kimberly Applegate said that often medical practitioners talk about the benefits of a procedure over risk (i.e., justification), but there is a need to transparently communicate uncertainties about low dose radiation effects. Dr. Applegate is one of the initiators of the Image Gently campaign, which aims to provide information to pediatricians, pediatric patients, and caregivers on the risks and benefits of medical radiation with the goal to encourage radiation reduction strategies.
Dr. Applegate said that ICRP would benefit greatly from a low dose radiation research program because it would provide new and high-quality scientific information to use for the commission’s recommendations and guidance. In her view, a potential program needs to have a strategic agenda so that it can focus on the questions that medical practitioners and their patients need answered. She was also in favor of a potential low dose radiation program promoting collaboration and coordination of its research.
ASTRO is the society of health care professionals who specialize in treating patients with radiation therapies. Although these therapies involve moderate to high radiation doses for the purpose of killing cancerous cells, they expose healthy tissue to low doses of stray radiation emanating from the treatment unit and therefore may increase the patient’s risk of developing secondary cancers. In addition, professionals who deliver radiation therapies may also be exposed to low levels of radiation.
Dr. Brian Maples said that ASTRO partners with other medical societies to fund pilot studies related to radiation biology. ASTRO also advocates for funding for radiation oncology and in recent years for low dose radiation research.
Dr. Maples identified two areas of low dose radiation research that can help health care professionals understand and communicate risks to patients: (1) mechanisms of radiation-induced carcinogenesis, and (2) individual susceptibility of the patient including epigenetic and genetic changes and pathway signaling changes.
AAPM is a scientific and professional organization concerned with patient safety for the medical use of radiation in imaging and radiation therapy. Dr. Larry Dauer identified the following areas of low dose radiation research of interest to AAPM:
- Use of big data analytics and multi-institutional data sets for predictive modeling of tumor and normal tissue response to identify those individuals who are more likely to benefit from a specific treatment.
- Understand mechanisms for secondary cancer and tissue effects at low doses of radiation to facilitate exploration of alternative treatment options.
- Quantify the benefit of imaging or treatment.
- Improve shared (doctor–patient) decision making by better understanding what information the patient needs regarding benefit and risk of imaging or treatment.
- Support epidemiological studies of cohorts, such as the Million Worker Study, that include large numbers of medical professionals of both sexes.
- Understand mechanisms of cataract and cardiovascular disease development.
Powerful Patient Inc. is an advocacy group with the mission to help patients receive the information they need to make decisions about their health care. Mr. Mike Lawing, a cancer survivor and co-host of the group, receives multiple diagnostic procedures that involve radiation to monitor his disease. He noted that the risk from the radiation was never a concern to him because he recognizes the benefits of the procedure in detecting early disease. He supported better understanding of risks at low doses through a coordinated low dose radiation research program and better-informed risk–benefit discussions with his medical team.