hormesis

Medical Physics recently hosted a point/counterpoint debate about the effects of assuming that all radiation carries a risk that justifies application of the ALARA (As Low As Reasonably Achievable) principle.

Here is an overview of the debate proposition.

The ALARA (As Low As Reasonably Achievable) principle is based upon the assumption that low doses of radiation might be harmful and, therefore, should be minimized for medical imaging procedures. Some consider, however, that such low doses are not only harmless but might also even be beneficial, and that advocating for use of the ALARA principle in the context of medical imaging fails to recognize that the risk is hypothetical and so serves to reinforce patients’ fears of radiation.

I’m biased. I am already convinced by nearly three decades worth of study, discussion and professional experience as a manager of people who are occupationally exposed to low dose radiation that there is no justification for assuming that radiation doses below about 10 Rem (100 mSv and 100 mGy) can cause cancer. Those doses do not cause any other effects that should concern people, in fact, their effects are analogous to moderate exercise because they stimulate human immune systems, stimulate disease resistance, and stimulate the body’s ability to repair itself and recover from stress.

Actions required by regulators and others seeking to minimize radiation dose with all “reasonable” efforts are costly, time consuming and often detrimental to health and safety.

My position and that of numerous colleagues in the nuclear energy industry and in other fields that use radiation or are affected by radiation doses is not universally accepted. In fact, it is a position that is not aligned with the official position of many recognized bodies of radiation protection experts.

This issue is extremely important. There are experienced, intelligent and dedicated professionals who hold viewpoints all along the spectrum between complete acceptance of radiation hormesis (a theory that radiation at moderate doses and dose rates provides a measurable net benefit for complex biological organisms) to complete acceptance of the linear, no threshold dose response model as an accurate predictor that can quantify radiation health effects with reasonable precision.

The participants in the Medical Physics point/counterpoint debate are both highly qualified and experienced professional practitioners whose arguments should be read in their entirety.

I’m in contact with Dr. Jeffry Siegel, who holds the position that adherence to principles of LNTH-based ALARA and a definition of “optimization” that assumes that the lowest possible dose is the best dose is both flawed and indefensible. Here is how he concluded his rebuttal in the debate on Medical Physics.

ALARA-dosing fosters radiophobia because denials that low-dose radiation confers a net benefit, and averrals that it confers risk, are demonstrable falsehoods that neglect the sciences of biology, chemistry, and physics that demonstrate the falsity of the LNTH and the reality of the hazards caused by any policy based on the ALARA principle.

His opponent, Dr. Cynthia H. McCollough concluded her rebuttal as follows.

Without a focus on optimization, a cavalier approach to imaging – one that aims for the best pictures and not the best balance of overall care – would ensue. Such disregard of the actual dosage applied would erode the public’s faith in imaging providers because of people’s underlying belief that radiation is dangerous. Failure to acknowledge potential risks would ignore these beliefs and undermine trust, which is at the core of the patient–doctor relationship. Clear recognition of potential risks and demonstration of technical expertise to minimize risk and maximize benefit is essential in maintaining the trust of our patients.

On the SARI email list, Siegel expressed his frustration with the fact that the editor of Medical Physics isn’t interested in a continuation of the debate to a point of resolution. I respect that journalistic publishing decision. All editors must choose topics and policies; even if the cost of publishing words is close to zero, there are limitations on what audiences will read.

As a partial solution, I offered Dr. Siegel a chance to continue the argument on this forum. He provided the following background points explaining the importance of allowing the discussion to continue.

In case you are not aware, the format of the P/CP debate in Medical Physics is that each person writes an independent opening. Then each debater receives the other’s opening and then writes a rebuttal. That’s it, we do not see each other’s rebuttal, so the debate format is short and sweet so there is little chance any issue will be resolved.

A surrebuttal is an effective debate device used to great advantage in a “search for the truth” in legal proceedings. Surrebuttals allow a reinforced and more targeted focus on conflicting ideas, only one set of which, at most, can be valid. And given that a surrebuttal is, by definition, a rebuttal of a rebuttal, some repetition is to be expected (the journal did not like the idea of repetition, apparently it did not appreciate its intent). Nevertheless and importantly, this repetition is necessary, since, rather than introducing new ideas, the purpose is to call attention to what are thought to be the relevant portions of an opponent’s arguments and highlight the major conflicting ideas in order to better frame the debate for the readers.

I was and still am prepared to go as many rounds as necessary – this is way too important an issue to not allow both sides to “go at it” until there is nothing left for one side to say. But I need an opponent and unfortunately this time I did not have one that agreed to participate in any further dialogue. I certainly hope that the Journal will consider adding the surrebuttal feature to its P/CP debate format in the future.

Atomic Insights is interested in moving towards a resolution on the issue. We hope that we can attract opponents into an honest, respectful and ongoing discussion that helps to alter the world’s radiation health paradigm. As a step in that direction, here is Dr. Siegel’s “surrebuttal” to Dr. Cynthia H. McCollough, his opponent in the point/counterpoint debate published in the December 2016 issue of Medial Physics.

Comment on: “Point/Counterpoint: Advocating for use of the ALARA principle in the context of medical imaging fails to recognize that the risk is hypothetical and so serves to reinforce patients’ fears of radiation”

To the Editor:

I am pleased that Dr. McCollough agrees that “credible evidence of imaging-related low-dose (<100 mGy) carcinogenic risk is nonexistent.” It is precisely this simple truth that discredits the LNT model and delegitimizes the need for ALARA-dosing, leading me to advocate an effort to undo the public’s misperception that all radiation is dangerous (carcinogenic), no matter how low the dose, including at the doses encountered in medical imaging.

Radiation is an extremely weak carcinogen, even at relatively high doses. Patients’ fear of radiation is certainly understandable, but not all radiation exposure is bad or associated with risk, in particular not at the low doses involved in medical imaging. Public misperceptions must not be disregarded or ignored; rather they must be addressed and corrected by providing people with accurate information. This could start with the recent nuclear accidents at Chernobyl and Fukushima where health risks were not due to radiation exposure but rather to the misguided radiophobic policies adopted by the authorities. For example, most people are unaware that no health effects are expected to result from the radiation exposure associated with the Fukushima nuclear accident, but that over 1600 individuals who were needlessly evacuated did actually die.

While it may seem logical for us to attempt to assuage the public’s fears by accommodating to their misperceptions and focusing on “optimization” in the absence of harm, I contend that this will only reinforce their misperception. The public’s trust in medical practitioners can only be preserved if we can convince them (public and physicians alike) that there is no harm to begin with. Indeed, accurate information about low-dose radiation is the only way to undo the fears. Granted we have to acknowledge the current disagreements among the experts, but no agreement will ever be reached if we accede to, rather than refute, their neglect of protective biological responses.

Jeffry A. Siegel, Ph.D.
Nuclear Physics Enterprises,
Marlton, NJ 08053

I’ll close this post with the reminder that there never was any experimental evidence that supported the assumption that radiation effects can be predicted by a straight line whose origin is zero dose and zero effects with every incremental increase in dose leading to a proportional increase in radiation health damage or risk of cancer induction. The notion of stochastic effects that has been taught and retaught for the past 60 years is based on a theory pushed mainly by a single man — Hermann Muller. There is a long and interesting story of how that theory was developed and promoted that is beyond the scope of this particular post.