Why action is needed
International and national advisory bodies
have a large influence on radiation safety regulations
BEIR VII Report by National Academy of Sciences
stated that atomic bomb survivor data are the most important data
cited 15-country study of radiation workers as supportive evidence for low-dose radiation cancer risk
Atomic bomb survivor data underwent
Major change in nature of data with the 2012 update. Significant curvature in dose-response of the updated data is not explainable by the LNT model but is consistent with radiation hormesis
BEIR VIII Scoping Meeting, November 2014
Did not recognize the major change in the nature of Atomic Bomb Survivor data
Continued to quote 15-country study of radiation workers as evidence for low-dose radiation cancer risk, in spite of withdrawal of Canadian data
Ignored new data that shows reduction of cancers from low-dose radiation, e.g. Nuclear Shipyard Worker Study and Study of second cancers in radiation therapy patients.
NCRP, in the Commentary No. 27 published in 2018, discussed several epidemiological studies with varying levels of support for the LNT model. The first study it quoted as providing strong support for the LNT model was the study by Grant, et al. on the cancer incidence of atomic bomb survivors. However, this publication states, in its abstract “At this time, uncertainties in the shape of the dose response preclude definitive conclusions to confidently guide radiation protection policies”. Such an indeterminate conclusion implies that the Grant et al. publication does not support any model. Thus, without even discussing the technical details of the publication, it is clear that the first strong evidence presented by the NCRP supporting the LNT model is not valid. It is concerning that the authors of the NCRP Commentary drew such a wrong conclusion from the publication. The other evidence presented in the Commentary also do not provide support for the LNT model.
NCRP has not been transparent in its decisions regarding low-dose radiation health effects: NCRP, which is a publicly funded organization, has not been transparent in its activities. For example, in 2017, NCRP published the draft of a Commentary regarding the LNT model and asked for public comments. Some SARI members submitted comments pointing out examples of evidence for radiation hormesis and pointing out the flaws in the evidence NCRP had presented supporting the LNT model. NCRP neither acknowledged nor responded to the comments, but published the NCRP Commentary No. 27 in 2018 without explaining why the submitted comments were ignored. SARI and XLNT Foundation set up an Exhibit Booth at the American Association of Physicists in Medicine (AAPM) Annual Meeting in 2018 in which a Poster critical of the NCRP Commentary No. 27 was displayed. There were many visitors to the booth. Several members of the NCRP visited the booth, but would not enter into discussion of the evidence quoted in the NCRP Commentary or defend the Commentary.
NCRP did not refute the evidence for radiation hormesis: In a Letter to the Editor responding to the NCRP Commentary No. 27, several pieces of evidence for radiation hormesis were presented. The Letter says, in part:
“…. many epidemiologic studies have indeed shown reduction of cancers following exposure to low radiation doses and radiation exposures at low dose rates, e.g. (Davis et al 1989, Berrington et al 2001, Sponsler and Cameron 2005, Hwang et al 2006, Doss 2018b, Tubiana et al 2011). In addition, exposure of the whole body or half body to low-dose radiation (10 cGy), 15 times in five weeks, resulted in improving the survival of non-Hodgkin’s lymphoma patients, indicating that the repeated exposures to low radiation doses had a cancer therapeutic effect (Sakamoto 1997). Whereas these studies did not determine the shape of the dose response by examining the cancer risk at a large number of doses, they did determine the cancer risk following exposure to low radiation doses and at low dose rates. Since these studies showed significantly reduced cancer risk following such radiation exposures, they directly contradict the LNT model. There are also alternative analyses or interpretations of the atomic bomb survivor data, which support the concept that following low radiation doses the cancer risk decreases, contradicting the LNT model (Doss 2013, Sasaki et al 2014).”
In their response, the authors of the NCRP Commentary claimed that the (above) quoted evidence (for radiation hormesis) is weak because in the studies quoted, the cancer risk of the study population is “biased downwards because occupational cohorts tend to be selected for good health compared with the wide range of health status in the general population”. Below is a list of the studies quoted and the cohorts compared.
Studies cited and cohorts compared
Davis et al 1989 (37) - TB Patients
Berrington et al 2001 (7) - Male Radiologists vs. Male Doctors
Sponsler and Cameron 2005 (5) - Radiation vs. non-Radiation workers
Hwang et al 2006 (38), Doss 2018b (6) -
Residents of radio-contaminated buildings vs. a reference population
Tubiana et al 2011 (39) - Cancer patients
Sakamoto 1997 (8) - Cancer patients
Doss 2013 (31) , Sasaki et al 2014 (40) - Atomic bomb survivors
As seen in the above list, none of the evidence quoted were such comparisons of occupational cohorts and the general population, and so their criticism is invalid.
NCRP has violated its Congressional Charter: NCRP’s Congressional Charter states that the objects and purposes of the corporation shall be “to collect, analyze, develop, and disseminate in the public interest information and recommendations about protection against radiation ….”. By stating in its Commentary that the the study by Grant, et al. on the atomic bomb survivors strongly supports the LNT model when it doesn’t, and neglecting to consider publications supporting radiation hormesis without giving a valid reason, NCRP has misled the public about the health effects of low-dose radiation and so the NCRP’s actions are not in the public interest. NCRP has violated its Congressional Charter.
Evidence for radiation hormesis has not been refuted: In 2020, XLNT Foundation set up an online debate website where it presented several examples of evidence for radiation hormesis and provided a facility for comments where those opposed to the evidence could present their views. Many individuals and representatives of organizations supporting the LNT model including representatives of NCRP and NRC were informed by email about the debate and asked to participate in the debate. However, no one has refuted the evidence presented.
With such practices, in spite of the growing evidence, the advisory body can continue to support the LNT model, citing faulty evidence and ignoring valid evidence
Hence, if no action is taken,
status quo of support for the LNT model by the BEIR committee and NCRP would likely to continue.
other advisory bodies which take the cue from NCRP and BEIR committee recommendations would continue their support for the LNT model
professional organizations and regulatory agencies would continue to use the LNT model
the tremendous harm from the use of the LNT model would continue
Thus, it is important to take actions to overcome the LNT model
Next section: FYI