NASEM report: U.S. low-dose radiation research needs DOE/NIH leadership

June 3, 2022, 9:29AMNuclear News

A new report from the National Academies of Sciences, Engineering, and Medicine (NASEM) estimates that $100 million annually will be required for the next 15 years to develop a coordinated research program led by the Department of Energy and the National Institutes of Health to study how low doses of radiation affect disease risk. The recommended research would investigate causal links to specific health conditions and better define the impacts of radiation doses, dose rates, types of radiation, and exposure duration.

“There is much we don’t know about the impacts of low-dose radiation exposures on our health—but recent advances in research, new tools, and a coordinated multidisciplinary research program could help us fill those gaps,” said Joe W. Gray, professor emeritus of laboratory medicine at the University of California–San Francisco and chair of the Committee on Developing a Long-Term Strategy for Low-Dose Radiation Research in the United States.

The committee’s work was sponsored by the DOE, and its report, released on June 2 prior to a June 3 public briefing, is now open for public comment ahead of a NASEM-hosted virtual town hall meeting on June 16. Comments can be submitted using the “provide feedback to the project” button on the committee's webpage. Submissions and any identifying information provided by commenters will become part of the public record and will not receive a response from the committee or from NASEM staff.

Questioning assumptions: Radiation exposure at low doses (below 100 milligray [mGy]) or low dose rates (less than 5 milligray per hour [mGy/h]) occurs in a range of medical, industrial, military, and commercial settings, and also from natural background radiation. Nearly half of the radiation dose that Americans receive comes from natural background radiation, and a significant majority of anthropogenic radiation is due to medical applications, including radiography, CT scans, and nuclear medicine.

While high doses can cause measurable health consequences, the health effects of low doses are exceptionally difficult to measure. Central to current radiation protection regulations is the linear no-threshold (LNT) model, which assumes that radiation harm increases linearly with exposure and that zero harm exists only at zero exposure.

While researchers have attempted to estimate cancer incidence from low-dose radiation exposure for decades, the NASEM committee is also recommending that research investigate evidence of an association of low-dose radiation with cardiovascular disease, neurological disorders, immune dysfunction, and cataracts. For some of these health outcomes, research has thus far relied on risk estimates from studies of individuals who were primarily exposed to higher doses.

Implications for radiation protection: The LNT model has shaped public perceptions of the risk of low-dose radiation. A "report highlights" document released with the NASEM report acknowledges “longstanding concerns” about low-dose or low-dose-rate exposures that “influence patient acceptance of medical diagnostic procedures; U.S. government decisions related to the future of nuclear power and clean energy policies; continuing efforts to assess the full range of radiogenic health outcomes of legacy exposures to fallout from nuclear weapons production, testing, and waste sites; management of nuclear waste; and plans for responding to radiological threats.”

In the full report, the authors assert that “new knowledge that emerges from the low-dose program can inform the radiation protection regulations and guidance in several ways: by improving understanding of adverse human health effects from exposures at doses and dose rates experienced by the U.S. population, identifying mechanisms for induction of these health effects, developing improved risk models for doses and dose rates at which direct measurement of risks is not possible, and ultimately developing more individualized risk estimates.”

Improved risk assessments may in turn “impact radiation protection by confirming that current regulations and guidance sufficiently protect human health or by supporting either more restrictive or less restrictive regulations and guidance.”

DOE and NIH to share the work: According to the NASEM report’s authors, “Research in low-dose and low-dose-rate radiation in the United States is currently limited and fragmented, lacking leadership and an overarching prioritized strategic research agenda.”

The solution proposed in the report is leadership of cross-agency research coordination by both the DOE and the NIH—with the DOE leading a portion of the strategic research related to computational and modeling research and the NIH leading the epidemiological and biological research.

While the DOE has been tasked by Congress to manage a low-dose radiation research program, the report notes that some communities have raised concerns that the DOE has inherent conflicts of interest because of its role in promoting nuclear technologies. The NIH, on the other hand, is “widely trusted by the scientific community and members of the public and does not have any regulatory responsibilities related to setting or implementing radiation protection standards; therefore, it has no perceived conflict of interest with leading low-dose radiation research through a cross-institutional effort.”

Within the NIH, the National Institute of Allergy and Infectious Diseases’ Radiation and Nuclear Countermeasures Program, the National Cancer Institute, and a new Advanced Research Projects Agency for Health (ARPA-H) could contribute to low-dose radiation research.

Research areas: The report sets 11 priorities for research that would leverage computing power, genetic research, and data-sharing systems that were not available to previous generations of researchers. Those priorities are organized under three broad categories of equal importance: epidemiological research, biological research, and research infrastructure:

Epidemiological research should improve our estimation of the risks for cancer and other health outcomes, determine factors that can modify these effects—such as genetics or lifestyle—and develop better analytical tools. Research priorities are as follows:

  1. Develop and deploy analytical tools for radiation epidemiology.
  2. Improve estimation of risks for cancer and non-cancer health outcomes from low-dose and low-dose-rate external and internal radiation exposures.
  3. Determine factors that modify the low-dose and low-dose-rate radiation-related adverse health effects.

Biological research should define the dose-response relationships for low radiation exposure, linking specific doses of radiation to health effects on the cellular level and the progression of disease. This research should also identify the effects of radiation on cellular and molecular features in order to establish causal links to adverse health effects, among other priorities. Research priorities are as follows:

  1. Develop appropriate model systems for study of low-dose and low-dose-rate radiation-induced health effects.
  2. Develop biomarkers for radiation-induced adverse health outcomes.
  3. Define health effect dose-response relationships around 10 mGy and 5 mGy/h.
  4. Identify factors that modify or confound estimation of risks for radiation-induced adverse health outcomes.

Developing a research infrastructure should include creating tools for sensitive detection of radiation and precise characterization of cell and tissue changes, harmonizing research databases, and ensuring researchers’ access to low-dose exposure facilities. Research priorities are as follows:

  1. Tools for sensitive detection and precise characterization of aberrant cell and tissue states.
  2. Harmonized databases to support biological and epidemiological studies.
  3. Dosimetry for low-dose and low-dose-rate exposures.
  4. Facilities for low-dose and low-dose-rate exposures.

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