Accepting the Science of Biological Effects of Low Level Radiation

By Rod Adams

A group of past presidents and fellows of the American Nuclear Society has composed an important open letter to ANS on a topic that has been the subject of controversy since before I first joined the society in 1994. The subject line of that letter is “Resolving the issue of the science of biological effects of low level radiation.” The letter is currently the only item on a new web site that has been created in memory of Ted Rockwell, one of the pioneers of ANS and the namesake of its award for lifetime achievement.

LNT and “no safe dose”

Ted was a strong science supporter who argued for many years that we needed to stop accepting an assumption created in the 1950s without data as the basis for our radiation protection regulations. That assumption, which most insiders call the “LNT”—linear no-threshold dose response—says that risk from radiation is linearly proportional to dose all the way to the origin of zero risk, zero dose.

Many people who support the continued use of this assumption as the basis for regulation plug their ears and cover their eyes to the fact that those who oppose the use of nuclear energy, food irradiation, or medical treatments that take advantage of radiation’s useful properties translate our mathematically neutral term into something far more fear-inspiring: They loudly and frequently proclaim that the scientific consensus is that there is “no safe dose” of radiation.

Some people who support the use of nuclear energy and who are nuclear professionals help turn up the volume of this repeated cry:

Delvan Neville, lead author of the study and a graduate research assistant in the Department of Nuclear Engineering and Radiation Health Physics at Oregon State University, told the Statesman Journal Apr. 28, “You can’t say there is absolutely zero risk because any radiation is assumed to carry at least some small risk.”

While most scientists and engineers understand that the LNT assumption means that tiny doses have tiny risks that disappear into the noise of daily living, the people who scream “no safe dose” want their listeners to believe it means that all radiation is dangerous. They see no need to complicate the conversation with trivial matters like measurements and units (I am being ironic here).

Scientists and engineers almost immediately ask “how much” before starting to get worried; but others can be spurred into action simply by hearing that there is “radiation” or “contamination” and it is coming to get them and their children. When it comes to radiation and radiation dose rates, we nuclear professionals have not made it easy for ourselves or for the public, using a complicated set of units, and in the United States remaining stubbornly “American” by refusing to convert to the international standards.

Aside: There is no good reason for our failure to accept international radiation-related measurement units of Sieverts, Bequerel, and Grays. Laziness and “it’s always been that way” are lousy reasons. I’m going to make a new pledge right now—I will use International System of Units (SI) units exclusively and no longer use Rem, Curies, or Rad. After experiencing the communications confusion complicated by incompatible units during and after the Fukushima event, the Health Physics Society adopted a position statement specifying exclusive use of SI units for talking or writing about radiation, and perhaps ANS should adopt it as well. End Aside.

Physics or biology?

Leaving aside the propaganda value associated with the cry of “no safe dose,” an important factor that supports a high priority to the effort to resolve the biological effects of low-level radiation is the fact that the LNT uses the wrong science altogether.

The LNT assumption was created by persons who viewed the world through the lens of physics. When dealing with inanimate physical objects all the way down to the tiniest particles like neutrons, protons, mesons, and baryons, statistics and uncertainty principles work well to predict the outcome of each event. An atom that fissions or decays into a new isotope has no mechanism that works to reverse that change. A radiation response assumption that applies in physics, however, is an inadequate assumption when the target is a living organism that has inherent repair mechanisms. Biology is the right science to use here.

At the time that the LNT was accepted, decision-makers had an excuse. Molecular biology was a brand new science and there were few tools available for measuring the effects that various doses of radiation have on living organisms.

The assumption itself, however, has since inhibited a major tool used by biologists and those who study the efficacy of medical treatments: Since all radiation was assumed to be damaging and could only be used in medicine in cases where there was an existing condition that might be improved, it was considered unethical to set up well-designed randomized controlled trials to expose healthy people to carefully measured doses of radiation while having a controlled, unexposed group.

Instead, health effects studies involving humans have normally been of the less precise observational methods of case-control or cohort variety, with occupationally or accidentally exposed persons. The nature of the exposures in those studies often introduces a large measurement uncertainty, and there are complicating factors that are often difficult to address in an observational study.

Science marches on, but will LNT?

Molecular biology and its available tools have progressed dramatically since the LNT was adopted by BEIR I (Committee on the Biological Effects of Ionizing Radiation) in 1956. It is now possible to measure effects, both short-term and long-term, and to watch the response and repair mechanisms actually at work. One of the key findings that biologists have uncovered in recent years is the fact that the number of radiation-induced DNA events at modest radiation dose rates are dwarfed, by several orders of magnitude, by essentially identical events caused by “ordinary” oxidative stress.

This area of research (and others) could lead to a far better understanding of the biological effects of low-level radiation. Unfortunately, the pace of the research effort has slowed down in the United States because the Department of Energy’s low dose research program was defunded in 2011 for unexplained reasons.

It is past time to replace the LNT assumption with a model that uses the correct scientific discipline—biology, rather than physics—to predict biological effects of low-level radiation. I’ll conclude by quoting the final paragraph of the ANS past presidents’ open letter, which I encourage all ANS members, both past and present, to read, understand, and sign:

The LNT model has been long-embedded into our thinking about radiation risk and nuclear energy to the point of near unquestioned acceptance. Because of strict adherence to this hypothesis, untold physiological damage has resulted from the Fukushima accident—a situation in which no person has received a sufficient radiation dose to cause a significant health issue—yet thousands have had their lives unnecessarily and intolerably uprooted. The proposed actions will spark controversy because it could very well dislodge long-held beliefs. But as a community of science-minded professionals, it is our responsibility to provide leadership. We ask that our Society serve in this capacity.

Additional reading

Yes Vermont Yankee (June 23, 2014)  “No Safe Dose” is Bad Science. Updated. Guest Post by Howard Shaffer

Atomic Insights (June 21, 2014) Resolving the issue of the science of biological effects of low level radiation

dna 432x201

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Adams

Adams

Rod Adams is a nuclear advocate with extensive small nuclear plant operating experience. Adams is a former engineer officer, USS Von Steuben. He is the host and producer of The Atomic Show Podcast. Adams has been an ANS member since 2005. He writes about nuclear technology at his own blog, Atomic Insights.

9 Responses to Accepting the Science of Biological Effects of Low Level Radiation

  1. Accepting the science of LNT is accepting the science. Writing letters in denial of the science, isn’t accepting the science. It’s science denial. ANS Past Presidents shouldn’t behave like former tobacco executives.

  2. Jason Kennerly

    Considering people die of heart attacks if the level of potassium in the blood/body is too low, it is trivial to say the concept of LNT as a law of biophysics is flat-out wrong, because the potassium on Earth is mildly radioactive.

    Since a minimum amount of radioactivity for health can therefore be established, the LNT model is demonstrated to be flawed at best.

  3. Dr. John Miller

    No post by Rod Adams comes without egregious disinformation. In this one he starts with a Big Whopper: that the LNT hypothesis was adopted without data. In fact, there is a considerable body of data supporting LNT. The BEIR VII report is just the latest National Academy of Sciences statement supporting LNT. Hey Rod, are you ever going to tell the truth?

  4. @Bob Applebaum

    Science is not acceptance of the consensus, especially when it has no basis in measurement, calculation or observation. It is unbecoming that you continue pursuing your argument by attacking the admirable people questioning the LNT instead of providing any credible science supporting your assertions.

    Thanks for stopping by and helping me to remember that all is right with the world. You’re predictable; I can count on you making a snide comment about any LNT-related post I write, even when I am blogging somewhere besides Atomic Insights.

    Once again, I’d like an answer to the following question, “How did Studsvik’s recent sale of US assets affect your net worth?”

    http://finance.yahoo.com/news/studsvik-ab-studsvik-sells-main-074000749.html

    Your former company –- RACE Holdings LLC -– made up most of the Memphis-based portion of the assets that were sold.

    http://www.webwire.com/ViewPressRel.asp?aId=12748#.U43DRZStkz0

    Studsvik is acquiring RACE for USD 27,5 million plus transfer of operating credit of USD 8,5 million. The financing of the acquisition has been secured and consists of a combination of own funds and new loans raised in connection with the acquisition. The sellers are the founders, together with the private equity firm Source Capital. The founders will continue to be active in the management of RACE.

    About RACE

    RACE Holdings LLC was founded 1999 and has since then been managed by the founders Gerald Webb, President and Bob Applebaum, Co- Chairman. RACE service offering includes services and logistics. The company owns and operates a special facility on Presidents Island, Memphis, Tennessee where dry and metallic LLW is treated. The facility has a strategic position with convenient access for transportation by road, railroad and water. The company also operates a set of transportation- and logistics services with a high capacity for radwaste components. It also operates its own logistics terminal.

    RACE currently employs a workforce of 120 personnel and has a strong client base. Prior to the Studsvik acquisition RACE Holdings LLC was owned by venture capital investor Source Capital and the founders.

    (Emphasis added.)

    It is not terribly surprising that a man whose wealth was accumulated from a business based on capitalizing on the excessive fear of radioactive material induced by the LNT assumption spends his retirement leisure time tracking and commenting on any piece that questions the LNT assumption.

  5. @Dr. John Dudley Miller

    I’ll bite. Can you detail the basis on which the LNT was adopted by BEIR I in 1956?

    At that time, the “gold standard” Life Span Study (LSS) of the Atomic Bomb Victims had been underway for about a half a dozen years and had not yet reported any useful results.

    Rod Adams

  6. @Dr. John Dudley Miller

    Just for fun, I thought I would check to see exactly when the first report was released from the Life Span Study.

    http://www.rerf.jp/library/scidata/lssrepor_e/tr05-61.htm

    It documents the mortality of the exposed group versus the control group for a period from October 1950-June 1958.

    It was published in 1962, six years after BEAR I established the LNT assumption as the basis for radiation regulation, replacing the previous threshold dose response model that had established a tolerance dose of 0.2 Gray per day.

    I think the following quote from that document provides some interesting food for thought.

    No evidence of higher general mortality was seen in the more heavily irradiated groups. When mortality from specific causes was studied the well known leukemogenic properties of radiation were clearly reflected, but for no other causes of death were radiation effects seen. An apparent effect in the area of anemia seems, at least in part, to result from diagnostic difficulties in the blood dyscrasias, inasmuch as some leukemias were so classified. It is also possible that for the blood forming organs the effects of radiation go somewhat beyond the production of classical leukemia.

    More intensive study of a very much larger body of data is now under way.

  7. Sidney Bernsen

    Certainly by now there must be sufficient evidence to demonstrate that there is no measurable difference in health effects from the variation in natural radiation environments and normal occupational doses. I.e. Other natural environmental effects clearly dominate and in effect prove that there is a”threshold”.

  8. Delvan Neville

    For the record, that quote is taken out of context. Here is the actual quote from the press release:

    “You can’t say there is absolutely zero risk because any radiation is assumed to carry at least some small risk,” said Delvan Neville, a graduate research assistant in the Department of Nuclear Engineering and Radiation Health Physics at Oregon State University and lead author on the study. “But these trace levels are too small to be a realistic concern.”

    I use the plain english explanation of LNT as the lead in to my summary on risk to defuse the alternative dialog, wherein Fukushima-panickers (e.g. ENENews) cite LNT as meaning “No amount of radiation is safe” to attempt to discredit a statement that, “These levels are safe.”

    If you have a single-sentence way to better explain, in plain English, that LNT 1) is an assumption and 2) that it assumes any small dose carries a small risk, I’d be happy to hear it.

  9. @Delvan Neville

    It’s probably not career enhancing advice, but here is what I would say.

    There is no evidence for any negative health effects from radiation exposures below 100 mSv received almost instantly.

    At a time when less was known about radiation heath effects, regulators made the conservative assumption that risk was proportional to dose down to a zero risk, zero dose level. Bureaucratic inertia has, so far, prevented that incorrect assumption from being changed.