Can Low-Level Ionizing Radiation Do Us Any Harm?

Abstract

The current system of radiological protection relies on the linear no-threshold (LNT) hypothesis of cancer risk due to humans being exposed to ionizing radiation (IR). Under this tenet, effects of low doses (i.e. of those not exceeding 100 mGy or 0.1 mGy/min. of X- or γ-rays for acute and chronic exposures, respectively) are evaluated by downward linear extrapolation from regions of higher doses and dose rates where harmful effects are actually observed. However, evidence accumulated over many years clearly indicates that exposure of humans to low doses of radiation does not cause any harm and often promotes health. In this review, we discuss results of some epidemiological analyses, clinical trials and controlled experimental animal studies. Epidemiological data indicate the presence of a threshold and departure from linearity at the lowest dose ranges. Experimental studies clearly demonstrate the qualitative difference between biological mechanisms and effects at low and at higher doses of IR. We also discuss the genesis and the likely reasons for the persistence of the LNT tenet, despite its scientific implausibility and deleterious social consequences. It is high time to replace the LNT paradigm by a scientifically based dose-effect relationship where realistic quantitative hormetic or threshold models are exploited.

A Contribution to the Current Debate About the Adequacy of The Linear-No-Threshold (Lnt) Model for the Risk Resulting From Radon Exposure

“…For some years, the "Polish school" of Dobrzynski et al [18] pleaded for hormesis of Rn exposure. A summary of their work is given in [34]. An often-quoted example is that in some areas of Ramsar (Iran) known as HBRA (High Background Radiation Area), radon concentrations are up to 3700 Bq/m³.…”

Indoor Radon Research in the Asia-Pacific Region

“…In addition, the results of a meta-analysis involving thirty-two case-control studies and two ecological radon studies on lung cancer, focusing on radon concentrations below 1000 Bq m −3 , do not support the finding that radon may be a cause of a statistically significant increase in the incidence of lung cancer [15]. The discussion about the effects of low radon exposure as well as low-level ionizing radiation is ongoing [16,17].…”

Letter re: “On Geraily et al - Comments”

“…There is increasing evidence that biological systems are indeed complex non-linear rather than linear in their response to low doses of ionizing radiation. 3 The precautionary (ALARA) principle (or conjectural safety factor) applied in medical radiological procedures thus causes undue concern in patients undergoing radiology and radiotherapy procedures and generally results in excessive material and social costs of such radiophobia. Then, adding “Nominal Risk” to the title of the paper of Ghazale et al and a short paragraph in their text, referring to the UNSCEAR 2012 Report 2 could serve to alleviate this irrational concern with health effects of low doses of ionizing radiation.…”