Is the Linear-No-Threshold Assumption Merely an Assumption?
In writing this series there were two primary controversies I wanted to address. The first, which most directly relates to the practices utilizing clinical nutrition, is that clinical nutrition, through the use of dietary changes and/or supplementation that not only includes potassium iodide but goes so much farther, can have a major impact on reducing the adverse health impact of ionizing radiation. However, the second, which I feel is just as important even though it does not directly relate to the practice of clinical nutrition, is that fear about both ionizing and non-ionizing (cell phones) radiation has not only led to reactions that are not only non-productive but sometimes detrimental to health. The best example of the idea that fear of radiation can lead to ineffective and unhealthy reactions is the desperate pursuit of potassium iodide supplements that occurred by many in this country right after the Fukushima nuclear power plant disaster. It seemed that fear that the Fukushima disaster would, within a few short weeks or months, lead to a radiation-induced apocalypse in this country blinded many thousands to the fact that potassium iodine only protects the thyroid against the effects of I-131, a radioactive isotope that has such a short half life that most of it would dissipate before reaching the continental United States. In contrast, as we subsequently learned, Cesium-137, which has a much longer half life than I-131 and is totally immune to any protective effects of potassium iodide, presents a much greater threat to health worldwide. Then, as we all know, the adverse impact of the almost irrational pursuit of potassium iodide in those days immediately following the tsunami was magnified by the fact that so many were so blinded by fear that they could not or were unable to realize that, at milligram doses significantly higher than the RDI for iodine, potassium iodide can lead to often serious health concerns.
Why are so many people so terrified of exposure to radiation, no matter what the amount? Of course,
your immediate response to this question might be that there is no need to ask this question. Isn’t it factual and obvious that any exposure to radiation, no matter how small, has potential for leading to serious health consequences either in the short term or long term? Actually it may surprise you, as it did me, that the idea that the health consequences of any dose of radiation, no matter how small, are adverse and increase in magnitude as the dose increases, a theory called the linear no-threshold (LNT) model, has, despite its general acceptance by most health care practitioners and the public at large, never been conclusively proven and continues to be controversial among radiation researchers. Therefore, in the final installment of this series, I would like to explore a sampling of the literature that seriously questions the validity of the LNT model and actually counter proposes a model based on hormetic concepts that low doses may not only be non-threatening to health but may, in reality, be beneficial.
Some basics on the nature of the LNT model and its history were provided by Hendee and O’Connor in their paper “Radiation risks of medical imaging: Separating fact from fantasy” (1). According to the authors concerning models of cancer risk from low doses of radiation:
“The model used most widely is the LNT model. This model is not chosen because there is solid biologic or epidemiologic data supporting its use. Rather, it is used because of its simplicity and because it is a conservative approach (ie, if it is not correct, then it probably overestimates the risk of cancer induction at low doses). For the purpose of establishing radiation protection standards for occupationally exposed individuals and members of the public, a conservative model that overestimates risk is preferred over a model that underestimates risk.”
The authors continue by discussing the history of the LNT model:
“The LNT model for radiation effects first appeared in the 1920s in Hermann Muller’s publications of genetic mutations in Drosophilia (fruit flies) induced exposure to x-rays. Muller was awarded the 1946 Nobel Prize in Physiology or Medicine, and in his acceptance speech, defended the use of the LNT model for the mutagenic effects (mutagenesis) of x-rays. At that time, there was substantial evidence that the LNT model was inappropriate for x-ray-induced mutations and that a threshold appeared to exist below which mutations did not occur. Muller ignored this evidence in his acceptance speech, as documented by Calabrese.”
The quote I would like to next feature from this paper points out a positive relationship between radiation exposure and health that I will address again when I review other papers on the subject:
“A recent report suggests that exposure of individuals to low-dose radiation may elevate the immune response and thereby protect the individuals from cancer.”
Despite this report, though, the LNT model has increased in popularity:
“Nevertheless, the LNT model has gained acceptance over the years as a predictor of cancer risk at low doses of ionizing radiation.”
Do other researchers share the same doubts about the LNT model for radiation? Consider this statement by Averbeck that can be found in his paper entitled “Does scientific evidence support a change from the LNT model for low-dose radiation risk extrapolation?” (2):
“The linear no-threshold (LNT) model has been widely used to establish international rules and standards in radiation protection. It is based on the notion that the physical energy deposition of ionizing radiation (IR) increases carcinogenic risk linearly with increasing dose (i.e., the carcinogenic effectiveness remains irrespective of dose) and, within a factor of two, also with dose-rate. However, recent findings have strongly put into question the LNT concept and its scientific validity, especially for very low doses and dose-rates. Low-dose effects are more difficult to ascertain than high-dose effects. Epidemiological studies usually lack sufficient statistical power to determine health risks from very low-dose exposures. In this situation, studies of the fundamental mechanisms involved help to understand and assess short- and long-term effects of low-dose IR and to evaluate low-dose radiation risks. Several lines of evidence demonstrate that low-dose and low dose-rate effects are generally lower than expected from high-dose exposures. DNA damage, signaling, cell cycle checkpoint activation, DNA repair, gene and protein expression, apoptosis, and cell transformation differ qualitatively and quantitatively at high- and low-dose exposures, and most animal and epidemiological data support this conclusion. Thus, LNT appears to be scientifically invalid in the low-dose range.”
MORE RESEARCH QUESTIONING THE VALIDITY OF THE LNT MODEL
As I mentioned above, evidence suggests that not only could low doses of radiation be relatively risk-free but could actually confer benefits to health. Karbownik and Reiter (3), in their paper entitled ” Antioxidative effects of melatonin in protection against cellular damage caused by ionizing radiation” that I reviewed in the installment on radiation protection by antioxidants, discuss some specifics in terms of dose and mechanism as to why low dose exposures might be health promoting:
“…a substantial body of data provides evidence for a protective action of ionizing radiation when applied in low doses. Ionizing radiation at low levels brings about what are referred to as adaptive responses and the stimulation of protective physiological mechanisms. These adaptive responses are specific for doses typically below 0.5 Gy. The antioxidant properties of ionizing radiation at low doses as well as the protective effects of pretreatment with low-dose ionizing radiation against the damaging effects of high doses have been observed in a variety of studies using different parameters of oxidative damage (e.g., chromosome aberrations and micronuclei formation in human blood lymphocytes and the level of lipid peroxides and the activities of antioxidant enzymes. Thus, the effects of low-dose ionizing radiation are similar to those brought about by antioxidants. Interestingly, in a comparative study of ionizing radiation at a 50 cGy dose and the antioxidant melatonin, these factors reveal a similar protective action against chemically induced lipid peroxides in mouse brain.”
Of course, this quote presents several statements that are certainly contrary to established radiation dogma. However, I feel strongly that we must resist the temptation to dismiss these statements in a knee-jerk fashion because, while they are not in alignment with what we have been traditionally taught about radiation and health, they are certainly in alignment with many of the most important tenets of stress physiology and key underlying principles of functional medicine. Therefore, I would like to offer some comments on several of the statements in the above quote.
To those familiar with research on stress physiology and the work of Hans Selye, the first three sentences, other than references to ionizing radiation, present nothing new. Selye and many other researchers who followed in his footsteps made it clear that not all stress inducing situations have negative consequences. In contrast, there is “good” stress, which is both type and dose dependent, that has the effect of improving health by up regulating host defenses. An excellent example of this that I have discussed at length in previous newsletters is the “hygiene hypothesis.” This hypothesis, which has been researched so often during the last 20 years it really should not be called an hypothesis anymore, indicates that proper immune system development during childhood depends on exposure to a certain amount of bacteria with mild to moderate levels of pathogenicity (Bacteria that might be found on domesticated animals or in ordinary household situations). Without optimal levels of exposure to these bacteria, which has been suggested by many researchers to be occurring more often in industrialized societies where concerns about cleanliness and antiseptic environments may be excessive, optimal immune development does not occur, leading to an increased incidence of allergic conditions.
The rest of the paragraph highlights a concept that has been known to functional medicine practitioners for years. This concept and the research upon which it is based makes it clear that the impact of exposure to adverse environmental agents is not solely determined, as many in the country believe, by levels of exposure. In contrast, the net impact is based both on exposure levels and the level and activity of endogenous physiologic coping mechanisms that exist in virtually all living beings. In the case of chemical toxins these coping mechanisms are mainly phase I and phase II detoxification enzymes. In the case of free radicals these coping mechanisms are antioxidant enzymes such as superoxide dismutase and molecules such as glutathione. The final important functional medicine point made in this quote is similar to the hygiene hypothesis scenario where infectious bacteria can play a “good guy” role by acting like a grain of sand in an oyster to stimulate optimal immune function. When toxins and free radicals encounter detoxification enzymes and antioxidants respectively, it’s not just a simple scenario of the “bad guys” being vanquished by the “good guys.” For, the toxins and free radicals, assuming amounts are not excessive, also play a “good guy” role by acting as positive stressors, stimulating optimal activity of endogenous detoxifying and free radical quenching components. In a similar fashion, as pointed out above, low doses of ionizing radiation, like bacteria and toxins, are not uniformly detrimental to health as is commonly assumed in our society. Rather, a significant body of research suggests that, because low levels of ionizing radiation can have a major stimulating effect on endogenous antioxidant mechanisms, they are not just benign but potentially quite vital to optimal antioxidant function.
Does this new model of how radiation impacts health, a model that suggests the impact will differ greatly depending on dose, have a name? Of course!! As you might expect, a portion of the name includes a word that we now use routinely when describing scenarios where a substance has differing impacts on health depending on dose, hormesis. In turn, the phrase that is being used to describe this alternative way of considering the impact of radiation on health is “radiation hormesis.”
RADIATION HORMESIS AND THE LINEAR-NO-THRESHOLD ASSUMPTION – A NEW BOOK CRITICALLY EVALUATING THE TWO THEORIES
In the remainder of this newsletter I would like to review a book that makes a very strong case that the radiation hormesis model presents a much more realistic viewpoint of how radiation affects health as opposed to the traditional LNT model. This book is entitled Radiation Hormesis and the Linear-No-Threshold Assumption by Charles L. Sanders which was published in 2010 (4). Before beginning my review, though, I want to point out that Sanders is highly critical of the LNT model, so much so that you may wonder if what you are about to read is nothing more than a rant that is long on outrageous claims and woefully short on referencing with quality, peer reviewed studies. Because, like most of you, my radiation education has revolved around the LNT model for years, I initially did find it difficult to accept some of the more broad-based claims and assertions you are about to read. However, because of profuse referencing of these statements with high quality, peer reviewed studies, I felt I had no choice but to take them seriously. Sanders wastes no time in making some bold and controversial declarations in the preface:
“Outrageous, unsubstantiated statements are made concerning the hazards of ionizing radiation, in spite of a vast published, peer-reviewed literature on molecular, cellular, animal, and epidemiological studies indicating not harm but benefit from low-dose ionizing radiation. Claims that as many as a million children across Europe and Asia may have died in the womb as a result of radioactive fallout from Chernobyl or claims that the health impacts of low levels of internal radiation are underestimated by between 100 and 1,000 times are common among antinuclear arguments. Such statements are fueled by proponents of the linear nonthreshold (LNT) assumption, which assumes that any dose of radiation, no matter how insignificant, results in increased mortality from cancer and other diseases.
The most dishonest, manipulative research I have ever seen in my nearly 50 years of participation in radiobiological research has been published by radiation epidemiologists who are proponents of the LNT assumption.”
The last quote from the preface I would like to share with you is very simple, big picture statement whose logic is hard to ignore:
“You might conclude that, if admirers of the LNT assumption were right about the risk from radiation, then the human race would not have survived natural background radiation, which in some places of the world is > 100 mSv/year (>40 times the global average.”
The next quote I would like to share provides some detail as to the questionable metabolic rationale behind the development of the LNT assumption:
“The validity of the LNT assumption has been challenged by many scientists. Abelson, editor of the journal Science, criticized the LNT assumption in 1994: To calculate effects of small doses, a linear extrapolation from large doses to zero is employed. The routine use of this procedure implies that the pathways of metabolism of large doses and small doses are identical. It implies that mammals have no defense against effects that injure DNA. It implies that no dose, however small, is safe. Examples of instances in which these assumptions are invalid are becoming numerous…The use of linear extrapolation from high doses implies that ‘one molecule can cause cancer.’ This assertion disregards the fact of natural large-scale repair of damaged DNA.”
The following quote provides a definition of hormesis as it relates to radiation:
“Hormesis is a dose-response phenomenon characterized by low dose stimulation and high dose inhibition. Mild stress-induced hormesis modulates and prevents aging and aging-related impairments. Low-level ionizing radiation is stimulatory at cellular, molecular, and organ levels. This radioadaptive response to low-dose radiation includes enhancement of antioxidant defenses, enzymatic repair of DNA, removal of DNA lesions, apoptosis, and immunologic stimulation, and is well established in the scientific literature. The benefits are inducible and transient, while the harmful stochastic effects of higher doses are seen after a long latency period. The effectiveness of these defense mechanisms varies with dose and dose-rate.
The radioadaptive response has been extensively studied, and is associated with increased lifespan as well as decreased mutations, chromosome aberrations, neoplastic transformations, congenital malformations, and cancer.”
The next quote provides some more detail about the adaptive response to low-dose radiation:
“The adaptive response involves DNA repair processes, radical scavenging induction, apoptosis, cell transformation, and cell cycle arrest. There are three major cellular defense systems against ionizing radiation that comprise the radioadaptive response: (1) protection against reactive oxygen species (ROS) by antioxidant molecules (such as glutathione) and detoxifying enzymes (such as catalase and superoxide dismutase); (2) DNA repair, particularly for double-strand breaks, that disappears at doses >0.5 Gy; and (3) elimination of genomically damaged cells by immune defenses and apoptosis at doses as low as a few mSv. The hormesis response is associated with increased lifespan, and decreased mutations, chromosome aberrations, neoplastic transformations, cancer, and congenital malformations.”
What radiation doses are most conducive to health enhancement? Sanders (4) points out:
“The adaptive response occurs at dose values ranging from 0.01 to 0.5 Gy and at dose-rate values ranging from 0.01 to 1.0 Gy/min. The radioadaptive response appears most beneficial at doses <100 mGy. The response begins to disappear at doses >200 mGv of low-LET radiation and is rarely seen at a dose of >500 mGv.”
The next quote considers the radioadaptive response from another perspective:
“The radioadaptive response is divided into three successive biological processes: (1) the intracellular response, (2) the extracellular signal, and (3) maintenance. The extracellular signal occurs by release of diffusible signaling molecules and/or by gap-junction intercellular communication.”
Similar to bacteria in the hygiene hypothesis, can low-dose radiation enhance immune function? Sanders (4) states:
“Low-dose ionizing radiation stimulates the immune system in vivo and in vitro, in part, by mobilizing hematopoietic progenitor cells into the peripheral blood.
Low-dose radiation enhances the adaptive immune response. The secretion of the proinflammatory cytokines IL-12 and IL-18 by mouse macrophages is increased by a dose of only 75 mGy. These cytokines participate in the adaptive immune response.”
Has this immune enhancing effect been reported in human studies? The author points out:
“Whole-body exposure to low doses of ionizing radiation stimulated immune function in humans. Villagers from Ramsar, Iran, receiving a background dose of 260 mSv per year, exhibited an increased lymphocyte-induced IL-4 and IL-10 production. IL-2 and IL-4 production by peripheral blood lymphocytes was also increased in X-ray equipment operators.”
As I suggested above, one of the strongest arguments in favor of the radiation hormesis model is the impact of natural, background radiation on human health. In chapter three of the book Sanders (4) discusses health effects in various areas of the world that demonstrate high levels of background radiation. First consider Kerala, India:
“The monazite-bearing, high-thoron-content sands of Kerala have a resident population of 200,000 living at these high-background radiation levels.”
What can be stated about cancer incidence in this area:
“There was no increase in all cancer mortality, all cause mortality, or decrease in longevity in native populations exposed to high levels of background radiation when compared with low-dose regions over an annual dose range of 0.8-700 mSv.”
Next, Sanders (4) discusses cancer statistics in areas of the US that are considered to have significant levels of background radiation:
“The age-adjusted cancer mortality rate for the U.S. population (1950-1967) decreased with increasing background radiation. A 20% lower cancer mortality rate was found in Idaho, Colorado, and New Mexico than in Louisiana, Mississippi, and Alabama where background radiation levels were nearly five times less than for those living in the mountain states.”
“About 250,000 Americans receive background exposures of ~40mSv/year living mostly in a handful of Rocky Mountain states, where lung cancer rates are much less than predicted by the EPA using the LNT assumption. Colorado indoor radon levels are well above the national average, averaging 7.3pCi/L. The USEPA estimates the average indoor radon level nationwide is 1.3 /Ci/L. Relative to other states, Colorado has the third lowest lung cancer death rate in the nation. For the period 1993-1997, the Colorado cancer death rate per 100,000 population was 48.2 among males and 25.6 among females. These rates are well below the national averages of 69.4 for males and 34.0 for females.
Proponents of the LNT assumption claim that each disintegration from naturally occurring radiation is harmful, giving a calculable cancer risk per disintegration. Studies clearly show that this is not true. The risk of cancer is zero or less than zero at background radiation doses that are up to a hundred times the world annual average dose of 2.5 mSv. Utilization of the LNT assumption to estimate cancer risk from exposure to background radiation is not credible. The large preponderance of epidemiological data demonstrates no effect or a protection against cancer for those living in HBRA regions of the world.”
Of course, we all know that sweeping conclusions based purely on epidemiologic data can and have led us astray over the years because of the numerous possible uncontrolled variables that are inherent with epidemiologic research. Nevertheless, given the compelling references Sanders (4) uses to support the claims in the above quote, I must admit that, in spite of years of believing in the LNT model, I am beginning to come around to his point of view.
Data that supports the claim that low doses of radiation exposure may be health promoting
The next set of quotes I would like to present support the contention that not only are low doses of radiation exposure benign but actually helpful in terms of promoting health. The following quote refers to radiologic technologists who, despite improvements in protective practices and technology during the last few years, have probably experienced higher exposure levels than the average American:
“A hormetic effect was observed among 142,517 U.S. radiologic technologists, with standardized mortality ratios (SMRs) for all cause and all cancer mortality of 0.69 and 0.79, respectively. Decreased risk was seen for all but one cancer type. Mortality patterns were generally similar for male and female technologists. Benefits of radiation exposure were somewhat decreased with increasing years of certified work experience.”
Based on similar data from other populations, Sanders (4) concludes:
“In summary, exposure of large medical worker and patient populations to ionizing radiation from medical-dental procedures for noncancer conditions, to a wide variety of radiological diagnostic tests, to radioiodine therapy, to radiotherapy for cancer and to radiologists and radiological technologists results in less mortality from cancer and other diseases.”
What about those employed in the nuclear energy industry? Surely they must have higher levels of radiation-induced cancer incidence than the population in general. Or do they? In his chapter on nuclear workers, Sanders (4) begins with the following:
“Millions of workers employed in the nuclear industry have been exposed to chronic low LET radiation, mostly to cumulative doses <100 mSv. A chronic threshold dose of ~10mSv/day or ~200mSv/year was found to cause an excess relative risk (ERR) for all solid cancers in irradiated human populations. Luckey was the first to find a biopositive effect of ionizing radiation on cancer formation in nuclear workers. A similar study published 17 years later found similar results, that cancer mortality among nuclear workers receiving cumulative lifetime doses of <100mSv experienced less cancer mortality.
No relationship was found between radiation exposure and increased cancer incidence in 65 epidemiological studies of populations living around nuclear power stations, fuel reprocessing plants and weapons facilities and testing sites in the U.K., U.S., France and Canada. However, evidence for reduced all cause and all cancer mortality has been found in most epidemiological studies of nuclear workers in scores of locations throughout the world, including nuclear power utility workers, nuclear fuel workers and plutonium workers.”
What about radon?
We’ve all seen the many reports over the last few years about how low levels of naturally occurring radon in our homes can pose a significant threat to health. How could Sanders (4) possibly not be in agreement? To begin his section on radon, Sanders (4) states:
“Numerous epidemiological studies of lung cancer risk and indoor radon and radon in underground mines have been published. BEIR VI, using the LNT assumption, estimates that 2,100-2,900 never-smokers in the U.S. die each year from radon exposure.”
Does Sanders (4) agree with this claim? The sentence following the above quotes suggests that the answer may be no:
“The BEIR VI committee does admit that it is especially difficult to estimate radon risks for never smokers in homes.”
However, before elaborating on his position on radon, the author discusses the specific nature of the supposed problem:
“Normal background radiation exposures are mainly in the range of 2.5-4.0 mSv per year. However, they can exceed 100 times these values in various parts of the world. More than half of the U.S. natural background radiation is associated with exposure to radon (mostly, 222Rn) and associated daughter radionuclides. Most homes in the U.S. have a radon concentration of about 2 pCi per liter giving a mean dose of 2.2 mSv per year. The typical lifetime, cumulative, residential radon exposure ranges from 14 to 20 WLM (working level month).”
According to Sanders (4), what is the impact of this level of radon exposure to health? Consider the following:
“Radon exposure involves both high-LET α– and low-LET γ-radiations. The γ-ray component is thought to stimulate hormetic effects. The beneficial effects of inhaled and radon-laden water are evident in Russian and European spa hospitals where 100,000s of patients are annually treated for a variety of inflammatory, immune, and hormonal disorders at radon concentrations up to a 1,000 times that of the Environmental Protection Agency (EPA) residential radon concentration limit. Protracted low-dose irradiation with radon enhances cell-mediated immunity and reduces pulmonary metastasis of melanoma in mice. Radon balneology (therapeutic effects of baths) has been shown to be effective in randomized double-blind studies. One study found an optimum therapeutic dose of radon of 2mSv given over a 2-week period. No increase in lung cancer has been found in radon spa patients or residents living in nearby high background radiation areas.”
Next, consider the following study by Cohen as described by Sanders (4):
“Cohen found a powerful protective effect against lung cancer from residential radon exposures. Cohen’s study encompassed about 905 of residents living in the U.S. The trend of county lung cancer mortality in males and females was strikingly negative with increasing radon exposure.”
The next quote I would like to present contains Sanders’ (4) explanation as to why radon exposure at the levels typically experienced by Americans is not only benign but beneficial to health. While I realize it is somewhat complicated, I feel it does provide a strong rationale for the hormetic processes I described earlier:
“A low-dose protective apoptosis-mediated (PAM) process, limiting potential cancer formation may be activated by low-dose, low LET gamma or X-radiations. Low doses of protracted low-LET γ-rays, associated with radon daughters and 60CO in Mayak workers, are thought to trigger the hormetic response and protect against stochastic effects of pulmonary α-irradiation at lung doses <1 Gy from inhaled radon and 239Pu alpha particle-induced, genomically damaged, transformed pulmonary cells, suppressing carcinogenesis in the lung up to lung α-doses of ~5 Gy. Low LET radiation reduces chemical carcinogen-induced cancers in rodents. Low dose ionizing radiation may enhance the elimination by apoptosis of cigarette-induced transformed pulmonary cells, thus decreasing lung cancer risk. The results indicated that not only did hormesis-associated protective processes prevent spontaneous cancer but also reduced the number of lung cancers associated with both α-irradiation and cigarette smoking.”
Yes, not only does Sanders (4) strongly assert, based on his review of the published literature, that radon, at typical exposure levels in the U.S., is not only benign but actually beneficial to health. Because of all the warnings we have received about radon over the years from supposedly credible sources, I realize that his claim in hard to believe. Nevertheless, even though I am not ready yet to sell my house and find a new one with high radon levels, I find the research that Sanders (4) presents hard to ignore.
Some interesting research on leukemia
It is generally assumed without question that ionizing radiation exposure can only lead to one outcome concerning leukemia, increased incidence. Sanders (4) presents research that suggests otherwise:
“A significant negative association between acute myeloid leukemia mortality in adults and γ-radiation were found in 41 of 95 French ‘Departments’. A negative nonsignificant association between childhood leukemia incidence and γ-radiation was observed in 22 countries of the UK. The incidence of leukemia and lymphoma were 19% less in males and 6% less in females living in the U.S. at an altitude of 2,000-5,300 feet when compared with those living at an altitude of <500 feet.”
While I realize that the data presented in the above quote is not only weak but epidemiologic in nature, thus in no way proving cause and effect, it does, in combination with everything else presented by Sanders (4) concerning radiation hormesis, provide food for thought.
Support for the radiation hormesis hypothesis from historical accounts
Some of the most interesting evidence Sanders (4) provides to support his radiation hormesis hypothesis is historical accounts:
“Shortly after Roentgen discovered X-rays in 1895, scientists learned that low-dose X-ray exposures cured and prevented infections and inflammations, primarily due to immune system stimulation. The stimulatory virtues of radium therapy for health and well-being were promoted until the late 1920s, when the hazards of very high radiation doses from internal radium became apparent. Studies showing that low-dose radiation is beneficial were simply ignored by the federal agencies and their advisory bodies. In 1936, a US National Academy of Sciences study discounted the known stimulatory effects of low-dose radiation.
Some of the many benefits of low-dose radiation identified in the early 1900s were cure of diphtheria, relief from arthritis and rheumatism pain and swelling, relief from symptoms of bronchitis, cure of gas gangrene and tuberculosis infections, and reduction of cancer incidence (in animals). Clostridium is the cause of gas gangrene, which is rapidly fatal if not immediately treated. During 1920s to 1940s, gas gangrene infections were successfully treated by exposure of the infected area to an X-ray dose of about 0.5 Gy. X-ray therapy often stopped the infection without requiring amputation. Mortality was cut to about 5% if patients were treated by radiotherapy prior to severe progression of the infection. A book published by Kelly and Dowell in 1942 on The Roentgen Treatment of Infections contained hundreds of case reports demonstrating the efficacy of low dose roentgen radiation in treating various infections and cancers.”
Sanders’ concluding statements
While the last chapter of the book is primarily a synopsis of the review and commentary presented in previous chapters, I feel the compelling language used by the author in this concluding chapter makes the presentation of some quotes worthwhile. First, some more of Sanders’ (4) in no way subtle thoughts on the LNT model:
“The LNT model is scientifically indefensible, yet still used because of its simplicity and convenience. ‘In order to make them believe the LNT dogma, radiobiologists have consistently misled students, physicians, professors, the media, the public, government advisory boards, and heads of nations.’ Radiation protection is in the pay of the LNT and the price that we are paying in terms of human life, resources and money is very high. The unethical behavior and pronouncements of many radioprotection groups and individuals needs to be questioned and openly debated.”
The author continues this train of thought:
“Fear of radiation is common in medicine and in the nuclear industry. The result of radiophobia is a frightened public due to exaggerated adverse health claims by professionals in radiation protection. Physicians and patients avoid exposures from diagnostic radiological examinations out of fear of the carcinogenic effects of ionizing radiation. It is widely recognized that patients in radiology and nuclear medicine are fearful about future cancer risk. Recent LNT-related estimates of cancer risk from CT scans use the LNT assumption have enhanced this fear. Actually CT scans are likely to decrease cancer risk.”
The last sentence in the above quote is referenced by a study by Scott BR et al entitled “CT scans may reduce rather than increase the risk of cancer (J Am Phys Surg, Vol. 13, pp. 7-10, 2008).
The next quote I would like to present contains an interesting set of observations about data on Japanese atom bomb survivors, all of which is referenced:
“Cancer risk estimates using the LNT assumption are largely based on studies of Japanese A-bomb survivors who experienced excess cancer at doses >100mSv. A total of 86,543 persons were exposed in Hiroshima and Nagasaki, of which 45,148 received doses <10 mSv. Over 90% of the exposed population received doses <500 mSv. To those receiving a single instantaneous dose of <1 Sv, there was a lifetime of improved health. No statistically significant effects have been found in birth defects, neonatal deaths, stillbirths, leukemia, solid cancers, death rates in offspring, sex ratio, growth and development during childhood, mental retardation, chromosomal aneuploidy and translocations or mutations in those receiving doses of <100 mSv. Japanese A-bomb survivors are living longer than unexposed controls, who received the same long-term medical care and other benefits as the exposed cohorts. Noncancer mortality rates for Nagasaki survivors was 65% of age-matched controls. All cause mortality rates in Nagasaki and Hiroshima combined showed a significant decreased relative risk for those exposed to 140 mSv. Correction for ‘special medical care of survivors’ failed to remove the beneficial response.”
In the last paragraph, Sanders (4) makes it abundantly clear concerning how he feels about those who have, in his opinion, falsely and deliberately led a smear campaign against the benefits of low-dose radiation and the concept of radiation hormesis:
“Political and vested interests are often behind the exclusion of radiation hormesis in setting radiation protection standards. Failure to study or even acknowledge the presence of radiation hormesis is a result of political influences within the radiation protection community. Adoption of current radioprotection standards based upon application of the LNT assumption does not protect against diseases at low doses but results in an increased risk. Proponents of the LNT say that there is nothing new about the studies on hormesis and that we must study more. They consistently reject and deliberately ignore unwanted data. They claim that radiation hormesis has not been seriously challenged in scientific peer-reviewed literature. They falsely claim that there is no reliable data at doses <100 mSv, and then ignore the abundant data that is available. They apparently hope to continue this mantra before their careers are over and their deception has been fully revealed. It is time to use common sense.”
SOME FINAL THOUGHTS AND OVERALL CONCLUSIONS
For most of us, when we think about or hear the word “radiation” what immediately comes to mind is the checkered history that is inextricably connected with the word. Rightfully so, Fukushima should be added to the pantheon of words and phrases that go back almost 100 years that are generally considered to be synonymous with fear of radiation. Thus, “Fukushima” will be added to the list that includes the names “Madam Curie,” who died for radium poisoning, Hiroshima, Nagasaki, and Chernobyl. However, does the fear that is rightfully instilled by these words also blind us to another word that should be used with all of these names – excessive?
I find it indeed unfortunate in our black and white, good and bad, sound byte world, we so often omit another word that I feel should be routinely used in virtually any scientific discussion regarding substances on earth – hormesis. As I have mentioned often since I wrote about the term in various newsletters, hormesis may be new to many but it is really nothing new. It’s just a two-dollar word for a concept supposedly coined by Paracelsus 500 years ago:
“The dose makes the poison”
As I hope I have demonstrated in this series, the Fukushima disaster just demonstrates once again that excessive radiation poses a real and formidable danger to mankind. Does it also lend proof to the LNT assumption that a minute fraction of what was released from Fukushima and Chernobyl is also a formidable danger to mankind justifying fear, panic, and massive ingestion of large amounts of potassium iodide, as we at Moss Nutrition saw first hand almost two years ago? Based on what I have just presented, I feel we must answer no.
Personally, while, I am not ready to dismiss the LNT assumption completely, despite the powerful suggestion to do so by Sanders (4), I must admit that the research that has formed the basis for this series has given me a great deal of comfort about the every day radiation exposures that are part of our society, ranging from cell phones to dental x-rays to the significant amount of natural background radiation from substances such as radon that has existed on earth for, most likely, millions of years. For, while I still fear excessive radiation no matter what the source, I take comfort in knowing that we are not defenseless against the small amounts of radiation that make up everyday living in our society. If we live the kind of life advocated by clinical nutritionists and functional medicine practitioners, we can maximize the team of dietary and supplemental antioxidants, optimally functioning endogenous antioxidants, and, when the situation demands, occasional use of potassium iodide supplementation, all of which make up a very under appreciated but very potent protective team.
Again, I am not ready to totally agree with Sanders (4) that the LNT assumption should be put in the same research trash heap that contains the assumption that eggs are so contributory to CVD that they should be avoided completely. However, I do feel strongly that the supporters of the LNT assumption, because of the fears about excessive radiation that have been emphasized continuously since World War II, have let fear blind them to the fact that, like virtually every other ailment that has plagued mankind, ill health caused by radiation is the result of a dynamic interaction between the radiation and the body’s defenses against radiation. While I have no doubt that these defenses were overwhelmed by the immediate, short range exposures that occurred in Hiroshima, Nagasaki, Chernobyl, and Fukushima, I also have little doubt that, for those who lived thousands of miles away from these disasters and lived the type of lifestyle we advocate while encountering the small amounts of radiation that are equal to the radiation levels that are part of daily living, these potent and formidable defenses have been grossly under appreciated.
Moss Nutrition Report #248 – 12/01/2012 – PDF Version
- Hendee WR & O’Connor MK. Radiation risks of medical imaging: Separating fact from fantasy. Radiology. 2012;264(2):312-21.
- Averbeck D. Does scientific evidence support a change from the LNT model for low-dose radiation risk extrapolation? Health Phys. 2009;97(5):493-504.
- Karbownik M & Reiter RJ. Antioxidative effects of melatonin in protection against cellular damage caused by ionizing radiation. P.S.E.B.M. 2000;225:9-22.
- Sanders CL. Radiation hormesis and the linear-no-threshold assumption. Berlin: Springer-Verlag; 2010.