NON-LINEAR RISK FROM LOW DOSE RADIATION EXPOSURE
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2007-31-12
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Dose-Response, vol 5, no 4, Table of Contents
(2007-12-01)
Special Issue Preface
(2007-12-01)
EFFECTS OF LOW DOSES OF RADIATION: JOINT STATEMENT FROM THE FOLLOWING PARTICIPANTS AT THE 15TH PACIFIC BASIN NUCLEAR CONFERENCE, SESSIONS HELD IN SYDNEY, AUSTRALIA, WEDNESDAY 18 OCTOBER 2006
(2007-12-01) Higson, DJ; Boreham, DR; Brooks, AL; Luan, Y-C; Mitchel, RE; Strzelczyk, J; Sykes, PJ
VERY LARGE AMOUNTS OF RADIATION ARE REQUIRED TO PRODUCE CANCER
(2007-12-01) Brooks, Antone L; Hui, Edmond; Couch, Lezlie A
The public fear of radiation is in part driven by the Linear No Threshold Hypothesis (LNTH), or the concept that each and every ionization increases the risk for cancer. Even if this were true, it is important to recognize that the increased risk is very small at low doses and cannot be detected. This paper demonstrates the large number of assumptions and extrapolations needed when using the LNTH to estimate low-dose cancer risk. The manuscript provides information at every level of biological organization suggesting that many of these linear assumptions do not hold. While the initial damage may be produced linearly with dose, the processing of that damage is very non-linear. Finally, the paper provides the unique prospective on radiation-induced cancer, demonstrating that it takes large amounts (total energy) of radiation delivered to large populations to detect an increase in cancer frequency. These observations are supported by both theoretical calculations and examples based on past human radiation exposure.
RAD-BY-RAD (BIT-BY-BIT): TRIUMPH OF EVIDENCE OVER ACTIVITIES FOSTERING FEAR OF RADIOGENIC CANCERS AT LOW DOSES
(2007-12-01) Strzelczyk, J; Potter, W; Zdrojewicz, Z
Large segments of Western populations hold sciences in low esteem. This trend became particularly pervasive in the field of radiation sciences in recent decades. The resulting lack of knowledge, easily filled with fear that feeds on itself, makes people susceptible to prevailing dogmas. Decades-long moratorium on nuclear power in the US, resentment of “anything nuclear”, and delay/refusal to obtain medical radiation procedures are some of the societal consequences. The problem has been exacerbated by promulgation of the linear-no-threshold (LNT) dose response model by advisory bodies such as the ICRP, NCRP and others. This model assumes no safe level of radiation and implies that response is the same per unit dose regardless of the total dose. The most recent (June 2005) report from the National Research Council, BEIR VII (Biological Effects of Ionizing Radiation) continues this approach and quantifies potential cancer risks at low doses by linear extrapolation of risk values obtained from epidemiological observations of populations exposed to high doses, 0.2 Sv to 3 Sv. It minimizes the significance of a lack of evidence for adverse effects in populations exposed to low doses, and discounts documented beneficial effects of low dose exposures on the human immune system. The LNT doctrine is in direct conflict with current findings of radiobiology and important features of modern radiation oncology. Fortunately, these aspects are addressed in-depth in another major report—issued jointly in March 2005 by two French Academies, of Sciences and of Medicine. The latter report is much less publicized, and thus it is a responsibility of radiation professionals, physicists, nuclear engineers, and physicians to become familiar with its content and relevant studies, and to widely disseminate this information. To counteract biased media, we need to be creative in developing means of sharing good news about radiation with co-workers, patients, and the general public.