Nuclear power could be a game-changer for energy affordability, grid reliability, and carbon reduction. However, it's been stifled for decades based on one deeply flawed scientific model: the linear no-threshold (LNT) model. The theory underlying this model suggests that any exposure to ionizing radiation, no matter how small, increases cancer risks and that risks rise in a linear way with exposure levels. It's not true.
The roots of LNT's dominance are more political than scientific. Its influence traces back to Hermann Muller, a geneticist and 1946 Nobel Prize winner. Muller's research in the 1920s and '30s claimed to show that radiation induces mutations in fruit flies, with no safe threshold. He became an ardent evangelist for the idea that even tiny radiation doses could cause hereditary defects.
However, it appears Muller may have deliberately misled his followers. For example, Muller falsely claimed in his 1946 Nobel acceptance speech that there was "no escape" from the conclusion that any radiation is harmful, despite being aware of evidence to the contrary.
Muller's influence peaked during the Cold War, as fears of radioactive fallout from above-ground nuclear weapons testing dominated public discourse. He warned that fallout could unleash a wave of birth defects based on unwarranted extrapolations from his fruit fly experiments. Though human studies of the offspring of Japanese atomic bomb survivors found no significant evidence of genetic damage, Muller helped convince the National Academy of Sciences (NAS) to exclude this inconvenient data when it convened an expert panel to assess fallout risks, opting instead to rely on his research using fruit flies and newer studies involving mice.
The internal dynamics of these scientific panels were less than objective. Edward Calabrese, a toxicologist at the University of Massachusetts Amherst, revealed that panelists openly strategized about how conclusions from their report could increase funding for their research. The head of the panel even referred to the members as "conspirators." This conflict of interest resulted in a biased final report that exaggerated health risks from fallout and omitted lower estimates to create a false veneer of consensus.
The deceptions worked. The panel's report led to widespread media coverage, which caused a sensation with its dire warnings. It catalyzed a major shift in government policy toward reliance on LNT for radiation regulations and risk assessment. Subsequent expert committees would repeatedly endorse LNT, often while downplaying or ignoring new findings that challenged it.
One such finding was the discovery of DNA repair mechanisms in the late 1950s by geneticists William and Liane Russell, which contradicted LNT's core premise that radiation damage always accumulates. When the NAS convened a new version of its radiation panel, the group initially sought to bury the repair discovery. An early draft of the panel's report omitted the repair findings. Only after several members protested—including, to his credit, Herman Muller—was the information added. Yet the committee still endorsed LNT.
In the 1990s, researcher Paul Selby uncovered serious flaws (or possibly deliberate misrepresentations) in earlier mouse studies by the Russells that had been pivotal to LNT's acceptance. Had these errors been known from the start, the regulatory regime surrounding radiation today could be very different.
More recently, the debate over LNT reignited within the Health Physics Society following the launch of a video series in April 2022 that detailed the checkered history of LNT. The series, featuring interviews with Edward Calabrese, sparked a vicious backlash. Emails obtained via Freedom of Information Act requests revealed an orchestrated pressure campaign by LNT proponents within the society, federal agencies, and the National Council on Radiation Protection and Measurements to discredit the video series and quash further discussion. The society's president, who spearheaded the video project, was censured by the Board of Directors of the Health Physics Society, in an apparent act of retaliation since some of these individuals were mentioned by name in the uncovered emails. The censure was ultimately overturned by a vote of the membership.
The sordid history of LNT is a cautionary tale of how flawed science, ideological bias, and political motives can distort the search for truth. Yet this dubious model remains and its influence extends beyond academic debates. LNT shapes onerous radiation regulations that dictate cleanup standards, nuclear plant oversight generally, and public perceptions of radiation risk, leading to exaggerated fears, higher energy costs, and perennially thwarted progress in the nuclear industry.
A more biology-based approach is needed—one that recognizes organisms' evolved capacities to repair low-dose radiation damage. Dose limits should be grounded in observable health effects, not speculative extrapolations from experiments on fruit flies. Additionally, it's time to discard the ALARA ("as low as reasonably achievable") concept that requires nuclear plants to continuously undertake costly efforts to lower exposure levels, based on the unfounded premises of the LNT model.
Science is supposed to self-correct through a culture of healthy skepticism and procedures like peer review. Yet these corrections often fail. Given the revelations about LNT's past and the many studies challenging its core assumptions, policymakers need to revisit the foundations of LNT-based regulation. Responsible reforms would lift burdens on the nuclear power industry and potentially dispel radiation phobias, opening the door to a more science-based approach to nuclear safety.
If we can learn from this history, we can build a scientific strategy around regulating nuclear technologies that helps people gain access to affordable, abundant, and reliable clean energy.
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