An Open Letter to Advisory Bodies[†] Regarding Low Dose Radiation Cancer Risk
Dear
Colleagues,
The linear no-threshold (LNT) model was adopted
worldwide for radiation safety purposes in the 1950s following the
recommendations of the various international and national advisory bodies [1]. The decision to use a linear model was based on the
observation of linear dependence of increased mutations in drosophila melanogaster
subjected to high dose radiation, and linear dependence of increased leukemias
in atomic bomb survivors exposed to high dose radiation. In spite of the considerable amount of evidence
available in the 1950s for the presence of a large threshold dose both for radiation-induced
mutations [2] and for leukemias [3], the concept of zero threshold dose was adopted by
the advisory bodies, violating basic scientific principles [4]. In addition, the consequent radiation safety
policies recommended by the advisory bodies to keep the radiation doses as low
as reasonably achievable prevented the study of radiation hormesis when it was
proposed in 1980 [5]. Thus, these recommendations derailed the scientific
method, since one unverified hypothesis was used to prevent the study of a
competing hypothesis, stalling scientific progress in the field, and leaving
the simple question whether the health effects of low dose radiation are
beneficial or harmful unresolved even after intense study for many decades [6].
Though there has been a considerable amount of
published evidence against the LNT model for radiation-induced cancers during
the past several decades [5, 7-9], the LNT model continues to be widely promulgated. The atomic bomb
survivor data, for example, have been used to support the LNT model of cancer
risk in the influential BEIR VII report [10] and in many peer-reviewed publications, e.g. [11]. Even in the latest update to the atomic bomb
survivor data [12], the authors have claimed that zero dose is the best
estimate for a dose threshold for solid cancer mortality, apparently supporting
the LNT model. However, their
dose-threshold analysis should be considered faulty since it restricted the
possible functional forms of the dose-response relationship a priori. An analysis that used a
more general functional form to fit the data has demonstrated that the presence
of a dose threshold cannot be excluded [13]. In addition,
a recent analysis of the atomic bomb survivor data using artificial neural
networks has revealed the presence of a threshold dose that varied with organ,
gender, etc. and the reduction of some cancers at low doses [14].
Another study used to justify carcinogenic concerns
from low doses of radiation in the BEIR VII report and other publications [11] is the 15-country study of radiation workers [15, 16]. A re-analysis of the
cancer mortality data of the Canadian nuclear workers [17] has resulted in a negation of the original conclusion
of the entire 15‑country radiation worker study regarding cancer risks from low
doses of radiation [18]. Also, a Bayesian analysis of the 15‑country study
data has shown there is too much scatter in the data to make a definitive
conclusion about the cancer risk from low doses of radiation, and that the
dismissal of reduction in overall cancers in the radiation workers is unjustified [19, 20].
Thus, the main arguments in the BEIR VII report (and
other publications) supporting the LNT model and increased cancer risks from
low doses of radiation cannot be considered valid. Further, evidence supporting
alternate (non-LNT) models and the beneficial effects of low doses of radiation
(i.e. radiation hormesis) have been published since the time of the BEIR VII
report [21-26], and the evidence presented in these publications have not been
challenged or repudiated in any peer-reviewed publication. The advisory bodies have however ignored such
publications without clearly stating why the evidence and arguments presented
in such publications are invalid, and they continue to promote the use of the
LNT model.
The continuing recommendations supporting the use of
the LNT model by the advisory bodies has had significant adverse societal
implications, particularly with regard to radiation protection policies and
public perception regarding radiation risk. For example, use of the LNT model
has led to substantial casualties in real-life situations because of the
ensuing fear of low doses of radiation among the general public, and the
actions taken by governments when handling radiological emergencies, e.g. in Fukushima [27]. The use of
the LNT model has also led to frivolous lawsuits when emergency responders were
exposed to low levels of radiation near Fukushima [28]. The
unwarranted concerns regarding low doses of radiation have discouraged study of
the use of low dose radiation for the prevention and treatment of cancer, even
though animal and human studies have demonstrated its positive potential [22]. Such concerns have also discouraged the study of low
dose radiation for reducing neurodegenerative diseases for which presently
there are no methods of prevention or control, even though animal studies have shown promise [29, 30]. Finally, unwarranted concerns about the low doses of radiation used
in medical imaging have led some patients to forego medically appropriate
examinations, even when such exams are necessary for accurate diagnosis or
therapeutic planning [31]. Thus, though
the LNT model was touted as a conservative measure and a simplified,
straightforward regulatory approach, its actual use has led to tremendous harm,
and it is imperative that alternative paradigms for radiation safety are considered
and adopted.
Considering the overwhelming amount of data that
supports the validity of low dose radiation adaptive protection [23] and the resultant invalidation of the LNT model, we
urge you to recognize this publicly with a declaration and recommend to governments
that they discontinue the use of the LNT model for radiation safety purposes,
supplanting it with a threshold model.
We would be happy to discuss this matter with you or
provide additional information for your consideration. Thank you for your kind
attention to this important issue.
Sincerely,
Mohan Doss, Fox Chase Cancer
Center, USA (mohan.doss@fccc.edu)
Wade Allison, Oxford
University, UK
Allen Brodsky,
Georgetown University, USA
Mervyn D. Cohen, Indiana
University School of Medicine, USA
Jerry Cuttler, Cuttler &
Associates, Canada
Ludwik Dobrzynski, National
Center for Nuclear Research, Poland
Vincent J. Esposito,
University of Pittsburgh, USA
Ludwig E. Feinendegen, Heinrich-Heine University, Germany
Krzysztof W. Fornalski,
Polish Nuclear Society, Poland
Leo S. Gomez, Leo S. Gomez Consulting, USA
Ed Hiserodt, Controls &
Power, Inc, USA
Patricia Lewis, Free
Enterprise Radon Health Mine, USA
Cynthia H. McCollough, Mayo
Clinic, USA
Mark L. Miller, Sandia
National Laboratories, USA
Steven S. Payne, National
Nuclear Security Administration (Retired),
Col USAF (Retired), USA
Charles W. Pennington,
Executive Consultant, USA
Jeffrey S. Philbin, Sandia National Laboratories (Retired), USA
Chary Rangacharyulu,
University of Saskatchewan, Canada
Charles L. Sanders, Korea
Adv. Inst. of Science and Technology,
S. Korea (Retired), USA
Bobby R. Scott, Lovelace
Respiratory Research Institute, USA
Yehoshua Socol, Falcon
Analytics, Israel
Michael G Stabin, Vanderbilt University, USA
Ruth F. Weiner, Former
Member of the NRC Advisory Committee on
Nuclear Waste and Materials, USA
Note:
All signers of this letter are members or associate members of SARI (Scientists
for Accurate Radiation Information, http://radiationeffects.org/).
The above letter represents the professional opinions of the signers,
and does not necessarily represent the views of their affiliated institutions.
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Note: This Letter was e-mailed
to the following advisory bodies on Feb 28, 2014:
ICRP, NCRP, UNSCEAR, IAEA, WHO, NAS
Copyright © 2014 by Scientists for Accurate Radiation Information
(SARI). You are encouraged to distribute
this Open Letter widely. You are given the
right to make copies of this letter in full or in part, provided the source of
the copy is identified as Scientists for Accurate Radiation Information (SARI),
with a link to the SARI website: http://radiationeffects.org
