Is low-level radiation a killer or a cure? Former MU professor’s theory spurs debate

Thirty years ago, an explosion ripped through a Soviet nuclear power plant, killing 31 workers and releasing a plume of radioactive fallout that drifted over vast swaths of the continent. Five years ago, a wall of water slammed into a Japanese nuclear power plant, triggering equipment failures and three nuclear meltdowns. As the world reflects on these tragedies, the year 2016 has become a time for revisiting our fear of nuclear power. Ever since the U.S. released a “rain of ruin” on Hiroshima and Nagasaki, the fear of radiation has been difficult to dislodge.

But one minority group of scientists is urging the country to reconsider that fear. These scientists argue that small amounts of radiation are not only less dangerous than commonly thought, but they are also good for you.

Their theory, ionizing radiation hormesis, aims to reframe the way the country treats tiny doses of radiation. The U.S. Nuclear Regulatory Commission, the agency in charge of the nation’s safety measures related to nuclear energy, is considering petitions to change its regulations for radiation exposure. If the hormesis proponents succeed, power plants could emit slight amounts of additional radiation to the surrounding areas, and workers could be exposed to as much as twice their current limit for the year. The theory under consideration represents a radical departure from the “as low as reasonably achievable” policy long ago adopted by the nation’s major regulatory agencies.

The concept is part of a larger theory of hormesis, an idea that is not widely accepted but that has become an international movement. It holds that exposure to small amounts of toxic substances help stimulate the body to cope with larger, harmful doses. Proponents argue this effect occurs with all kinds of harmful agents, such as the insecticide DDT, which is banned in the U.S. because it causes cancer, and lead, which damages the nervous system.

The theory challenges a tenet of toxicology that “the dose makes the poison.” This holds that large doses are more harmful, and smaller doses are less so. Hormesis, which flips the role of chemicals at low-doses, runs counter to decades of thinking about toxic substances, according to David Ropeik, an author and consultant who specializes in risk communication and risk perception.

Radiation hormesis, the most controversial hormesis theory, argues that low doses of radiation — usually at or just above natural background radiation levels — kick disease-fighting systems in the body into gear, helping to fight cancer and, possibly, other diseases.

But the subtle effects of low doses of radiation remain difficult to understand. Cancer is a complex disease, one that’s impossible to study in controlled human experiments. A lot of radiation health data comes from studies of Hiroshima bomb victims, according to William Miller, a professor of nuclear science and engineering at MU. “We just strictly have no other option,” he says.

This controversial idea has become an international movement, though still a fringe one. And it’s a movement that largely grew out of the work of a former MU professor named Don Luckey, who died in 2014. Luckey didn’t live to see his pet project elevated to a national proposal, but he would watch his theory expand far beyond his one-man crusade.


A biochemist originally from Wyoming, Luckey had first encountered hormesis in the late ‘40s while studying antibiotics. When Luckey was at the University of Wisconsin, where he earned his doctorate in biochemistry and nutrition, he injected baby chicks with small amounts of antibiotics, according to a 2011 profile of Luckey in the St. Louis Post-Dispatch. The chicks grew far healthier than expected for such a low dose, and Luckey started to question the linear models.

He continued his research into the matter in the 1970s as he moved to MU’s medical school as the chairman of the biochemistry department. There, he made his first foray into the subject of radiation hormesis by exposing plants to varying doses of radiation from the university’s research reactor, according to the St. Louis Post-Dispatch profile. He watched the slightly irradiated plants flourish.

He was not the first to propose the idea of radiation hormesis – it has its origins in the 19th century – but he rediscovered it, and in 1980 he wrote a book, “Hormesis with Ionizing Radiation,” that aimed to comprehensively cover the topic. Radiation hormesis had become the newest angle to his obsession with the necessary elements for life. The obsession had led him through a career path that had included working for a dog food company and as a consultant about the nutritional needs of astronauts for NASA. For Luckey, hormesis explained natural background radiation as one of those essential elements of life, something that kept the body’s defense mechanisms working properly, according to his daughter donna luckey, a retired University of Kansas associate professor who taught architecture and environmental planning and who prefers not to capitalize her name for artistic reasons. To Don Luckey, low levels of radiation were a gift from the environment.

Don Luckey first started studying radiation hormesis in the 1940s. Photo courtesy of donna luckey.

Don Luckey first started studying radiation hormesis in the 1940s. Photo courtesy of donna luckey.


Both sides of the argument agree that large doses of radiation are bad. Ionizing radiation, the type that has enough energy to do damage, strikes the DNA in the cells, either killing the cell or causing the DNA to mutate. That mutation can sometimes lead to cancer. The more radiation there is, according to the standard linear model of radiation, the more often the rays come in contact with the cells, and the more the risk of radiation poisoning or cancer rises. This model, which matches the dose of the radiation to the amount of risk, is called the “linear no-threshold model” of radiation. According to this model, radiation becomes less and less dangerous as it decreases at a steady rate – picture a straight, diagonal line on a chart – until there is no radiation at all.

But at a certain low level, the controversy begins. Hormesis supporters say low-level radiation causes the body’s repair and defense mechanisms to gear up and protect the cells from future radiation. The opposing side says radiation at this level still causes damage.

Because of the inherent difficulty of observing cellular-level effects at very low doses, there is no absolute and unavoidable scientific conclusion about hormesis that all scientists can agree on. To make matters more confusing, the two camps often disagree about what kind of studies can even be considered valid.

One way to see the effects of low-dose radiation is to study a large number of people exposed to low levels of radiation. One study funded by the CDC, Department of Energy and several other national and international groups and agencies monitored more than 300,000 French, British and American nuclear industry workers an average of about 30 years. The study found a higher rate of leukemia among these workers than in the general public, even though they were subjected to only low doses. Other similar studies have looked at Chernobyl cleanup workers and patients who had medical CT scans, coming to similar conclusions. There also have been studies showing risks from background radiation, the ever-present and low-dose radiation in the environment caused by both natural and human-caused sources. And the EPA says radon, a naturally occurring radioactive gas, is the second leading cause of lung cancer after smoking.

Hormesis supporters can also point to large-scale studies, including ones following the survivors of the atomic bombs dropped in Hiroshima and Nagasaki, that they say show the benefits of low-dose radiation. While the supporters acknowledge victims who received high doses of radiation experienced serious and long-term health effects, Luckey pointed to studies that found survivors who received low doses had lower rates of leukemia deaths and other health issues than people who were not affected by radiation. Another study suggests that people living with higher concentrations of radon in their homes have lower rates of cancer.

But the theory’s main proponent, toxicologist Ed Calabrese from the University of Massachusetts Amherst, questions these studies. They have too many possible factors to conclude anything with any confidence, he says. And if hormesis is a real phenomenon, it will have a very modest effect, according to Calabrese. “There is simply too much uncertainty, too many variables unknown,” he writes in an email.

Ian Fairlie, a radiation consultant to the NRC, says these quibbles can often come down to distorted statistics about significance, used to dismiss results or cast doubt on the findings. “Uncertainty is also what the tobacco manufacturers said in the 1970s and 1980s about lung cancer,” he writes in an email. “Sound familiar?”

The other battleground in hormesis is over controlled lab experiments. Calabrese prefers them as evidence, saying they eliminate most of the uncertainties he finds troubling in the large statistical studies. While scientists can’t expose people to low doses of radiation for their research, they can test the effects of low doses on lab rats. He says these studies clearly point to a hormetic effect.

But Fairlie contests these kinds of studies, saying that the effect of a small amount of radiation on a small number of animals can’t be presented with any statistical significance. The researchers would either need thousands of lab rats, he says, or they’d need to increase the doses — defeating the point of the study. The large-scale human studies are the only reliable evidence, he says.

The debate is unlikely to subside any time soon, according to Ropeik, the risk consultant. “There’d have to be some kind of massive breakthrough evidence, and this field doesn’t lend itself to it,” he says.

Ropeik argues that until new technology is invented that allows scientists to clearly see the effect of chemicals and radiation at the level of genetics, scientists will continue to argue over the strengths and weaknesses of low-dose studies. “It’s not just black and white,” he says.


Luckey faced a major pushback immediately after publishing his 1980 book. The 1970s had been a decade of regulation — the EPA and the NRC were both formed, and both began emphasizing the dangers of radiation. The Three Mile Island accident occurred in 1979, underscoring the need to closely monitor radiation. And Luckey was arguing for a fundamental reordering of radiation’s place in the world. Many accused the nuclear industry of using hormesis to attack pricey safety regulations. “If you say hormesis out loud in the radiation regulation community, people figure you’re a charlatan,” says Mark Miller, one of the petitioners in support of hormesis. “There are some issues you just don’t raise in polite company.”

But it seemed that Luckey welcomed the challenge, according to his daughter donna. “He tended to enjoy the controversy,” she says. “He definitely liked to believe his work was going to cause people to rethink what’s going on.”

The anti-hormesis backlash did sometimes get to Luckey, donna says, and he often felt his work was being unfairly suppressed for political reasons. But until he died at the age of 94, he continued to promote and support the idea of hormesis. He even kept a uranium-flecked rock by his bedside, according to the St. Louis Post-Dispatch profile.

His dogged loyalty to the theory made him a hero to some of the later hormesis supporters, but it also could rankle. He was a biochemist among radiation researchers, and some resented him for shaking things up from the outside.

Luckey considered some practices surrounding radiation safety to be fearmongering, donna says, and, he would often march on past what some would have considered prudent. Calabrese says Luckey was sometimes combative and uncompromising in a way that might have hurt his own cause. He recalls a time when Luckey titled an article, “EPA is a carcinogen.”

“One has to really control one’s emotions,” Calabrese says.

Despite the obstacles he faced, Luckey’s ideas seemed to have spread. In 1985, a Japanese scientist who had been fascinated by hormesis after reading Luckey’s book organized the four-day-long Conference on Radiation Hormesis held in Oakland, California. Speakers came from all over the country and the world. Luckey spoke a couple times at the conference, but it was clear the radiation hormesis theory had spread far beyond him, and that he was no longer the force behind it.

“I think it was good for my father to finally feel like he wasn’t alone,” donna says.


The 1985 conference in Oakland marked the beginning of the second — and current — stage in the modern radiation hormesis campaign. The second stage is led by Calabrese, who was another speaker at the event and who studies hormesis as a larger concept. Calabrese, now 69, was just starting to focus professionally on hormesis, and he credits the conference for energizing his interest.

Like Luckey, Calabrese thinks hormesis is essential to the possibility of life on earth, allowing living organisms to adapt and survive exposure to harmful substances.  And he’s willing to bet his reputation and career on it, just as Luckey did. Calabrese says that while he believed Luckey could be too belligerent, he admired Luckey’s determination. “He was really ahead of his time,” he says. “Luckey was challenging the entire biology community to see a new principle.”

Some will argue that Calabrese tackles the debate with similar vigor, and possibly with similar outcomes. “Calabrese is such a true believer in his cause and so fiery that the world is rejecting his ideas,” Ropeik says.

Opponents sometimes hurl a more serious accusation at Calabrese and others promoting hormesis — that their research is driven by big chemical companies wanting to transform their products from poisons to cures. It’s no secret that Calabrese, who now receives much of his funding from the Air Force, also has received funding from ExxonMobil for his hormesis research. The practice of large companies funding research in universities is common, but opponents can still raise questions.

Frederick vom Saal, a professor of biological sciences at MU whose research often focuses on bisphenol A, a controversial chemical used in plastics, is one of those opponents. He blasts hormesis as an unsubstantiated theory that arose from the tobacco industry’s attempt to convince people that slight amounts of nicotine are good for their health. Now, he says, chemical companies have taken over funding research for the theory. “This is not a credible issue and not a real field of science,” he writes in an email. “It is only interesting from the perspective of how corporations can spend millions to subvert science and make a ridiculous idea seem sensible.”

In his book “Is a Little Pollution Good for You?: Incorporating Societal Values in Environmental Research,” Michigan State professor and science ethicist Kevin C. Elliott writes that some people worry hormesis could be used as a tool against regulatory agencies. “By appealing to hormesis, industry groups might be able to argue that regulators should avoid using safety factors and instead perform detailed (and time-consuming) research to determine the precise levels at which normally toxic chemicals begin to produce beneficial effects,” he writes in the book.

The hormesis supporters have their own argument about wrongdoing by the other side. They believe the 1950s scientists who supported the linear model of radiation damage uncovered and then buried evidence that the effect dropped off — and reversed — at very low levels. They argue that ever since then, the fear of radiation has caused people to unfairly suppress any evidence of the benefits.


Calabrese, like Lucky, has been frustrated by the attacks on hormesis research, and he says he’s often shut down completely. “It can be very personal,” he says. He says that between 1998 and 2000, he submitted six or seven papers about hormesis to the country’s leading toxicology journal, and he was rejected each time. “I’m a full professor here,” he says. “I really know how to do that crap.”

Finally, in 2000, he decided to address his critics more directly by hosting a three-day conference in which he debated some of the more vocal ones in front of roughly 200 people. Calabrese says he got reasonable criticism of his data set and holes in his argument. “I really have to up my game if I’m going to move this topic ahead,” he thought to himself. So he spent another year beefing up his data, looking at 21,000 studies, trying to find how often they supported hormesis. He eventually published a paper in the Journal of Toxicological Sciences – the same one that had rejected his earlier papers — that laid out how often hormesis was found in the scientific literature. A couple other major journals refused to review his paper, but he later wrote a commentary in the journal Nature, and the press took notice. The Wall Street JournalThe Boston Globe and Discover wrote articles about Calabrese and hormesis in the early 2000s. “Before I knew it, hormesis had become a big deal,” Calabrese says.


The three scientists behind the NRC petition submitted their documents in February 2015, as the NRC was doing a regular review of its standards for radiation protection. While they do differ slightly, two of them serve to support that of Carol Marcus, a professor of nuclear medicine and of radiation oncology and radiological sciences at the University of California-Los Angeles’ medical school.

Marcus’ petition asks for the agency to trade out its linear no-threshold model for a hormesis one, and to allow nuclear plant workers to receive up to 100 millisieverts of radiation a year if the doses are highly spread out. One hundred millisieverts is the amount often cited as the threshold for low doses, though scientists debate this too. Her petition would also raise the public allowance of radiation exposure to the current worker doses. “Why deprive the public of the benefits of low dose radiation?” she writes in her petition.

Her petition’s final request has invited censure from anti-nuclear groups like Beyond Nuclear, and would set the same dose exposure standards for pregnant women, children, embryos and fetuses.

Beyond Nuclear writes in comments to the NRC about the “special vulnerabilities” of pregnant women, embryos and children. “Much about this phenomenon is not yet discovered, but this uncertainty should not be used as an excuse to expose humans to undetermined damage from radiation during the most vulnerable stages of life,” the comments say.

Marcus, however, disagrees about the uncertainty. “There are places in the world where background radiation is ten times or more than places in the U.S.,” Marcus says. “Embryos and children and fetuses grow up in these areas, and they don’t have any higher cancer rates.”

In June, the NRC opened the petitions up to comment, and after an extension, it closed the comment period in November. “We are now considering the 635 comments we received as well as the petitions themselves,” Maureen Conley, who works in the NRC’s Office of Public Affairs, writes in an email. “No telling how long that will take.”

While none of the three petitioners seem optimistic about the chances of the NRC changing its policies, they believe the support for hormesis is the strongest it’s ever been.

The three scientists behind the NRC petitions are all members of Scientists for Accurate Radiation Information, an outspoken pro-radiation group intent on preventing “unnecessary, radiation-phobia-related deaths, morbidity, and injuries,” according to its website. For Marcus, some of those deaths come from the fear of using diagnostic tests like X-rays that give off radiation. She believes the adoption of hormesis will make people less afraid of small amounts of radiation and of these tests. “We’ve been brainwashed to think all radiation kills us,” she says.

Mark Miller, another petitioner, is a retired health physicist who worked in Albuquerque at Sandia National Laboratories, which are operated by the U.S. Department of Energy. He says hormesis could save lives if another disaster like the meltdowns at Fukushima happens again. If hormesis is real, then thousands of Fukushima refugees who would have only received low doses if they’d stayed were ripped from their homes unnecessarily. Different studies debate how dangerous the radiation from Fukushima actually was.

And Mohan Doss, the third petitioner and a medical physicist who works at the Fox Chase Cancer Center in Philadelphia, says it’s important to study hormesis for cancer prevention.


Even with an organized movement, however, radiation proponents face a difficult climate. “The fear of nuclear power is connected to a handful of emotional factors,” says Ropeik, the risk specialist. “It is rooted in a historical fear.”

Ropeik, who has received funding from the nuclear industry, argues that the debate over hormesis has to be understood as a matter of belief systems as much as science. “It goes against the grain of how society thinks about dangers,” he says. “We, as people, don’t like having to open our minds about things we assumed are threats.”

Ropeik places blame on both sides of the debate for the “culture war” that he says the debate has become. Oftentimes, the opponents of hormesis attack the researchers rather than research, he says. But the proponents of hormesis also fail to recognize the legitimate reasons people have to fear radiation. After all, cancer is a uniquely frightening disease in the American mindset, and the fact that radiation is associated with “big industry” can lead to deep distrust. Sometimes hormesis proponents argue that people are irrational for fearing low levels of manmade radiation when they are already exposed to low levels of natural radiation. “That’s arrogant,” Ropeik says about that argument. “That’s ignoring the fact that it doesn’t feel the same.”

Today, the petitioners are fairly sure the NRC won’t adopt hormesis. They know the regulatory agencies will want to err on the side of caution. But they still have reason to be optimistic. The use of hormesis in academic papers has spiked over the last few years, and Calabrese’s pro-hormesis organization, the International Dose Response Society, has hosted a conference every year that draws in scientists from around the country. Mark Miller remembers the 2015 one as having standing-room-only sessions. He considers it a sign of how much the support has grown over the years. “I could never in my life imagine such a fast-forward,” he says.

DSCF1002 (1)

Don Luckey, fourth from the left, visited Japan in 2007 for a radiation hormesis symposium with his daughter, donna luckey, first on the left. They were hosted by Sadao Hattori, third from left. Photo courtesy of Jerry Cuttler.

And there is one place where Don Luckey’s ideas seem to have taken root. In Japan, where 70 years ago two atomic bombs left a dark gash in world history, Luckey’s book found a welcoming target. One scientist there who had been influenced by Luckey’s book also began researching hormesis and began to use low-dose radiation in preventative treatments. “In Japan, they basically honored him as the person who made this field viable,” donna says about her father.

Jerry Cuttler, an independent radiation consultant out of Toronto who met Luckey in the 1990s, remembers going with Luckey to a symposium in Tokyo in 2007, hosted by the same scientist who organized the Oakland conference. Donna luckey also went along, as her father was then in his late 80s and needed help getting around. The two remember being greeted warmly, honored at a banquet, and taken to tour low-dose radiation spas, where people would soak in radioactive rays or drink the radon-infused water.

While in Japan, the two men gave lectures, and Cuttler remembers people lining up to take photos with them. One of the prominent Japanese scientists took Cuttler on a tour of his hometown to the north.

They returned to the U.S. feeling like they’d been treated as celebrities. Luckey settled back into his normal life — and back into the hormesis crusade.

2 thoughts on “Is low-level radiation a killer or a cure? Former MU professor’s theory spurs debate

  1. Pingback: Hormesis | Is low-level radiation a killer or a cure?

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