INL makes a case for eliminating ALARA and setting higher dose limits

When it comes to public dose limits, increasing the limit from 100 to 500 mrem per year “would maintain a substantial safety margin while better aligning with scientific evidence and enabling more cost-effective implementation of beneficial nuclear technologies across energy, healthcare, and industrial sectors.”

Executive imperative: President Trump issued two executive orders related to radiation protection on May 23. Executive Order 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” directs the NRC to “adopt science-based radiation limits. In particular, the NRC shall reconsider reliance on the linear no-threshold (LNT) model for radiation exposure and the ‘as low as reasonably achievable’ standard, which is predicated on LNT.” Executive Order 14303, “Restoring Gold Standard Science,” states that “highly unlikely and overly precautionary assumptions and scenarios should only be relied upon in agency decision-making where required by law or otherwise pertinent to the agency’s action.”

In response to those orders and “renewed nuclear prioritization,” the authors of “Reevaluation of Radiation Protection Standards for Workers and the Public Based on Current Scientific Evidence”—including INL lab director John Wagner and five certified health physicists on the INL staff—set out “to determine whether regulatory frameworks should be revised to better align with the weight of contemporary scientific understanding while maintaining appropriate safety margins for both workers and the public, acknowledging that some level of scientific uncertainty will likely persist and that the full societal benefits of expanding nuclear power are difficult to quantify.”

The authors acknowledged “the assistance of Claude, an AI assistant developed by Anthropic, in developing and refining portions of this report.”

Uncertainty and debate: The report describes the science on low-dose radiation effects as “unsettled,” with “ongoing debate among experts and competing theoretical frameworks.”

While radiation protection standards have been built on the LNT model, which assumes that radiation risk is directly proportional to dose, with no threshold below which the risk is zero, “alternative theories, including threshold models and hormesis (potential beneficial effects at low doses), have gained scientific support.”

The report concludes that “rather than claiming scientific certainty where none exists, aligning radiation protection standards with current scientific understanding represents a prudent step toward realizing these benefits while maintaining appropriate safety margins for workers and the public while acknowledging that some level of scientific uncertainty will likely persist.”

An ongoing low-dose radiation scientific and policy debate intensified after the May 23 executive orders were released. At issue is not just the science or specific dose limits but also how to optimize radiation protection regulation, which many agree has become focused on driving dose as low as possible despite increasing costs and diminishing returns as dose approaches zero.

The American Nuclear Society convened an expert advisory group which stated that “instead of reigniting an esoteric scientific debate, the group believes that the NRC and other federal agencies should focus on applying the ‘as low as reasonably achievable’ (ALARA) principle in the manner it was originally intended,” as a balanced optimization process, and added that “any changes to either the real or perceived independence of the NRC would undermine the credibility of the regulatory process and the industry, both domestically and internationally.”

The Health Physics Society and the National Council on Radiation Protection and Measurements held a series of open forums in June, and the NRC held a comment-gathering meeting on July 16 on its radiation protection regulatory framework.

Three health physicists and ANS members—Emily Caffrey, Amir Bahadori, and Shaheen Dewji—published their own recommendations in response to EO 14300 on June 27, following the HPS/NCRP open forums, recognizing “a time-sensitive opportunity to unify, modernize, and harmonize the U.S. system of radiation protection” and urging a focus on “practical protection.” They asserted that “scientific discourse regarding health effects at low doses, along with continued debate over the application of the linear-no-threshold (LNT) model as a regulatory construct, should not paralyze regulatory policy,” and suggested that that the U.S. establish a “de minimis” threshold for regulation “in a transparent, scientifically defensible process.”

More on the report’s recommendations: Given their assessment of available evidence, the authors of the INL report assert that an occupational-dose limit of 5,000 mrem “eliminating all ALARA requirements and limits below this threshold . . . would maintain protection against demonstrable radiation risks while eliminating requirements for continuous dose reduction in ranges where health effects have not been conclusively demonstrated.” Further, “substantial evidence suggests that even 10,000 mrem/year may maintain a reasonable safety margin based on available epidemiological and radiobiological data.”

Actual workplace exposures are considerably lower than the regulatory occupational dose limit of 5,000 mrem/year, and are below historical levels. The report attributes the lower exposures to current ALARA requirements, and states by way of an example that “in 2023, only 22 percent of monitored [Department of Energy] personnel received any measurable dose; of those, the average was just 50 mrem, 1 percent of the regulatory limit. Over the past five years, only one monitored individual within DOE received a dose above the 2,000 mrem administrative control level.”

For the general public, “the current dose limit of 100 mrem per year also appears to be overly restrictive given the lack of observable effects at much-higher levels of natural background radiation experienced by millions of people worldwide. A revised public-dose limit of 500 mrem per year would maintain a substantial safety margin while better aligning with scientific evidence and enabling more cost-effective implementation of beneficial nuclear technologies across energy, healthcare, and industrial sectors.”

The European Union, Japan, and Canada have annual occupational dose limits that, while not identical, roughly match or exceed the current U.S. limit of 5,000 mrem, according to a table provided in the report. Annual public dose limits for the EU, Japan, and Canada match the current U.S. limits at 100 mrem.

Ongoing research, in context: In 2022, the National Academies of Science, Engineering, and Medicine issued a report calling for $100 million of annual funding for low-dose and low-dose-rate research over 15 years. The committee recommended that the DOE and the National Institutes of Health collaborate to split the workload and proposed research scope. At the time, Joe W. Gray, professor emeritus of laboratory medicine at the University of California–San Francisco and chair of the NASEM committee that produced the report said, “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.”

Then, in August 2023, new data from the International Nuclear Workers Study (INWORKS), which includes a cohort of U.S. workers from DOE sites, entered the debate with “evidence of an increase in the excess relative rate of solid cancer mortality with increasing cumulative exposure to ionizing radiation at the low dose rates typically encountered by French, U.K., and U.S. nuclear workers [and] evidence in support of a linear association between protracted low dose external exposure to ionizing radiation and solid cancer mortality.” The findings were limited by methodological challenges, however, including lifestyle factors such as smoking status.

The INL report states that the INWORKS findings “have been interpreted by some researchers as supporting the continued use of the LNT model for radiation protection purposes.”

While some current research is investigating the health effects of low-dose radiation beyond cancer, the INL report focuses squarely on what is “widely interpreted” to be the central issue in LNT and radiation exposure health effects: cancer. The report states that “recent studies have investigated correlations between chronic low-level radiation exposure and various health effects, including Parkinson's disease and cardiovascular effects. However, it is important to stay focused on the central issue with LNT: that all radiation exposure, without threshold, will create deleterious health effects—an assumption widely interpreted as cancer risk.”

The report also notes that Congress has appropriated “more than $50 million for low-dose research” in the last five years, including $20 million in fiscal year 2024 to restart a low-dose radiation research program administered by the DOE’s Office of Science. That research “will further refine scientific understanding of low-dose radiation effects and inform regulatory approaches,” and according to the report it is “being coordinated through the White House Office of Science and Technology Policy.”