Genetic radiation risks: a neglected topic in the low dose debate

Abstract

Objectives: To investigate the accuracy and scientific validity of the current very low risk factor for hereditary diseases in humans following exposures to ionizing radiation adopted by the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection. The value is based on experiments on mice due to reportedly absent effects in the Japanese atomic bomb (Abomb) survivors.

Methods: To review the published evidence for heritable effects after ionising radiation exposures particularly, but not restricted to, populations exposed to contamination from the Chernobyl accident and from atmospheric nuclear test fallout. To make a compilation of findings about early deaths, congenital malformations, Down's syndrome, cancer and other genetic effects observed in humans after the exposure of the parents. To also examine more closely the evidence from the Japanese A-bomb epidemiology and discuss its scientific validity.

Results: Nearly all types of hereditary defects were found at doses as low as one to 10 mSv. We discuss the clash between the current risk model and these observations on the basis of biological mechanism and assumptions about linear relationships between dose and effect in neonatal and foetal epidemiology. The evidence supports a dose response relationship which is non-linear and is either biphasic or supralinear (hogs-back) and largely either saturates or falls above 10 mSv.

Conclusions: We conclude that the current risk model for heritable effects of radiation is unsafe. The dose response relationship is non-linear with the greatest effects at the lowest doses. Using Chernobyl data we derive an excess relative risk for all malformations of 1.0 per 10 mSv cumulative dose. The safety of the Japanese A-bomb epidemiology is argued to be both scientifically and philosophically questionable owing to errors in the choice of control groups, omission of internal exposure effects and assumptions about linear dose response.

Keywords: Congenital malformation; Down´s syndrome; Environmental radioactivity; Internal radiation; Low level effects; Sex-ratio; Still birth.

Figure 1.

Down’s syndrome before and after the Chernobyl accident (A) West Berlin and (B) Belarus. From Scherb H, et al. Naturwiss Rundsch 2011;64(5):229-239, with permission from Stuttgart [47].

Figure 2.

Regions of interest in a theoretically predicted dose response relation (see text and ECRR 2010). Exactly this dose response is seen in infant leukemia rates after Chernobyl in Greece, Germany (three dose regions) Wales, Scotland and Belarus [84]. From Busby C. Aspects of DNA damage from internal radionuclides; 2013 [6]. ^aQ is the background cancer rate in the population at background radiation levels, the position where the graph starts.

Figure 3.

Dose response for infant leukemia in the countries examined in meta-analysis of five reports in Busby 2009 [84] (UK data from Childhood Cancer Research Group Oxford). Effect is fractional excess relative risk, and dose is given by UK National Radiological Protection Board in mSv.