According to Wikipedia, the Linear No-Threshold Model is as follows:
“The linear no-threshold model (LNT) is a
dose-response model used in radiation protection to estimate stochastic health
effects such as radiation-induced cancer, genetic mutations and teratogenic
effects on the human body due to exposure to ionizing radiation. The model
assumes a linear relationship between dose and health effects, even for very
low doses where biological effects are more difficult to observe. The LNT model
implies that all exposure to ionizing radiation is harmful, regardless of how
low the dose is, and that the effect is cumulative over a lifetime.”
This model is commonly used
to set public policy regarding radiation exposure. However, the validity of the
model is disputed, and detractors say it should not be used to set public
policy. Other models suggest that low-dose radiation is not harmful and may
actually be beneficial. It has also been argued that the LNT may have created
an irrational fear of radiation. That fear has been termed radiophobia. No one
disputes the harm of high levels of radiation. The issue of debate is basically
lower levels. However, it has yet to be determined whether low levels of
radiation are harmful, beneficial, or neutral.
“In 2005 the United States National Academies' National
Research Council published its comprehensive meta-analysis of low-dose
radiation research BEIR VII, Phase 2. In its press release the Academies stated:
“The scientific research base shows that there is no
threshold of exposure below which low levels of ionizing radiation can be
demonstrated to be harmless or beneficial.”
A 2005 report by the French
Academy of Sciences stated:
“The LNT concept can be a useful pragmatic tool for
assessing rules in radioprotection for doses above 10 mSv; however since it is
not based on biological concepts of our current knowledge, it should not be
used without precaution for assessing by extrapolation the risks associated
with low and even more so, with very low doses (< 10 mSv), especially for
benefit-risk assessments imposed on radiologists by the European directive
97-43.”
Ted Nordhaus, writing for The
Ecomodernist, recently wrote about the LNT based partly on an article in
Scientific American by Katy Huff, Assistant Secretary for Nuclear Energy at the
Department of Energy during the Biden Administration, and professor of nuclear
engineering at the University of Illinois. The article is paywalled so I can’t
access it, but she argues against the Trump administration’s recent executive
order to reconsider the use of the LNT. The EO announced on May 23, 2025,
explains that the use of the LNT has been a strong factor in hampering the
deployment of nuclear energy in the U.S. since 1978:
“Between 1954 and 1978, the United States authorized the
construction of 133 since-completed civilian nuclear reactors at 81 power
plants. Since 1978, the Nuclear Regulatory Commission (NRC) has authorized only
a fraction of that number; of these, only two reactors have entered into
commercial operation. The NRC charges applicants by the hour to process license
applications, with prolonged timelines that maximize fees while throttling
nuclear power development. The NRC has failed to license new reactors even as
technological advances promise to make nuclear power safer, cheaper, more
adaptable, and more abundant than ever.”
“This failure stems from a fundamental error: Instead of
efficiently promoting safe, abundant nuclear energy, the NRC has instead tried
to insulate Americans from the most remote risks without appropriate regard for
the severe domestic and geopolitical costs of such risk aversion. The NRC
utilizes safety models that posit there is no safe threshold of radiation
exposure and that harm is directly proportional to the amount of exposure.
Those models lack sound scientific basis and produce irrational results, such
as requiring that nuclear plants protect against radiation below naturally
occurring levels. A myopic policy of minimizing even trivial risks ignores the
reality that substitute forms of energy production also carry risk, such as
pollution with potentially deleterious health effects.”
Nordhaus describes and
critiques Huff’s position regarding the LNT and low-dose radiation:
“Huff has published a scathing critique of the reset,
arguing that in the absence of new research proving that there are no negative
health effects at low doses, and extensive public input into any proposed new
standard, changing the NRC’s health standards “effectively demands that NRC’s
decision-making be political rather than scientific” and is hence “unethical.”
“Huff insists that she is defending science over
politics. But her position is, in fact, no less political than that of the
Trump administration and far more extreme. She argues for a strict
precautionary approach to radiological health risk while insisting that any
change to this approach requires new research to falsify a hypothesis (LNT)
that is both unproven and likely unfalsifiable. Meanwhile, she obfuscates the
actual consequences of changes to public dose standards, which are minimal even
accepting the LNT hypothesis, and claims, without evidence, that doing so will
result in the loss of public confidence in nuclear energy.”
Thus, he, correctly in my
opinion, explains the issue as one where the Precautionary Principle has long
prevailed over other ways of looking at low-level radiation. He says that
changing the LNT and the unnecessary hampering of nuclear energy development
are long overdue. He argues that humans are already exposed to low-dose
radiation from the sun, radon, and anthropogenic sources such as X-rays and CT
scans, and that cumulatively, these sources exceed levels that the public and
workers at nuclear plants, even with occasional accidental exposure, are
exposed to.
“Everybody is exposed to background radiation that is
significantly higher than low dose exposures that they might be exposed to from
nuclear reactors. And large numbers of people will die from cancers caused by
other factors. As a result, even when tracking very large populations exposed
to low doses of radiation over a very long time period, it is extremely
difficult, if not impossible, to identify a statistically significant increase
in cancer incidence or mortality above the background rate experienced by
populations that have not been exposed to excess low dose radiation.”
Huff calls for more research,
as those wedded to the Precautionary Principle often do, but Nordhaus argues
that more research is not likely to solve the epidemiological issue.
“Science simply can’t resolve the uncertainty about
radiological health effects at low dose exposures. The decision to regulate low
dose effects that are unavoidably speculative is no less political than the
decision not to do so. Huff prefers a more precautionary approach than the
Trump administration. But that is a conflict over social and political values,
not science.”
He argues that the Chernobyl
disaster was an extreme outlier due to a poor nuclear energy design by the
Soviets and a very poor response by them as well – for instance, iodine tablets
were not given to many workers exposed to keep the meltdown under wraps. Even
in those lights, the deaths and later cancers have been lower than would be
expected by the LNT model.
Nordhaus thinks the U.S. will
likely raise the maximum allowable dose from nuclear plant operations that the
public could be exposed to from 1 mSv to 5 mSv, twenty times lower than the
100mSv threshold for observable radiological health effects.
“Given the low dose and extreme uncertainty that there
is any effect at all, there is no appreciable difference between a 1 mSv
maximum dose and a 5 mSv maximum dose. Both doses are far higher than anything
that any nuclear reactor would likely expose the public to in anything other
than a worst-case accident and yet are still de minimis in relation to a dose
that one might reasonably expect to have significant public health consequences.”
Nordhaus also argues, as
other nuclear advocates such as climate scientist James Hansen have also
argued, that the air pollution from fossil fuels definitely kills people, and
replacing some of that fossil fuel generation with nuclear generation will eliminate
some of those deaths. Thus, more nuclear energy would likely result in overall
better health outcomes for people. That is a reasonable argument that is
difficult to argue against ands yet another situation where precaution might
cause more harm than good. Thus, it is reasonable to assume that raising
thresholds for low-dose exposure could actually help to save lives. He notes
that Huff and others argue that raising exposure limits will undermine public
confidence is simply a self-fulfilling prophecy, not based in reality. One
might argue why we should accept deaths from fossil fuel pollution and not
accept possible but not likely very slight increases in future cancers due to
ionizing radiation exposure.
“The public confidence game, in these ways, is circular
and well past its sell date. We are over fifty years past the era when the
radiological risk norms that both Democrats and much of the nuclear industry
continue to adhere to were established. The anti-nuclear movement is dead. The
soft energy path is a fantasy. Fear of the unknown when it comes to nuclear
energy and radiation may still be around, but new research suggests that it has
substantially attenuated.”
“Arguing about speculative cancer deaths from
speculative future low dose radiation releases that may not even exist, when
verifiable harm is still being caused by fossil fuels, does not serve the
public good.”
“Bottom-line, there is simply no reasonable basis for
the claim that the changes to radiological health standards currently being
discussed by the Trump administration and the NRC will be material to the
public’s health. Nor that updating those standards will spark a backlash from
the general public. It’s time to get on with the business of reform at the NRC
and building a globally competitive 21st-century nuclear industry.”
I wholeheartedly agree with
Nordhaus that our nuclear energy industry has been so hampered by regulations,
slow approvals, and unsubstantiated safety and public health precautions that
it has been rendered wounded and dysfunctional, raising costs to unnecessarily
high levels and increasing timelines for deployment unnecessarily. The raising
of the exposure limit is both reasonable and a step in the right direction, but
there are many other hurdles to overcome before the U.S. might see a real
renaissance in nuclear energy.
References:
The
Public Confidence Game: How Extreme Radiological Precaution Undermines Both
Public Health and Public Confidence in Nuclear Energy. Ted Nordhaus. The
Ecomodernist. February 9, 2026. The Public Confidence Game - by Ted
Nordhaus
Loosening
radiation exposure rules won’t speed up nuclear energy production: Relaxing
radiation safety standards could place women and children at higher risks of
health issues. Katy Huff. Scientific American. January 23, 2026. Weaker radiation limits will not help
nuclear energy | Scientific American
Linear
no-threshold model. Wikipedia. Linear no-threshold model - Wikipedia
Ordering
the Reform of the Nuclear Regulatory Commission: A Presidential Document by the
Executive Office of the President on 05/29/2025. Federal Register. Federal
Register :: Ordering the Reform of the Nuclear Regulatory Commission
