Health Impacts of Low-Dose Ionizing Radiation: Current Scientific Debates and Regulatory Issues

Abstract

Health impacts of low-dose ionizing radiation are significant in important fields such as X-ray imaging, radiation therapy, nuclear power, and others. However, all existing and potential applications are currently challenged by public concerns and regulatory restrictions. We aimed to assess the validity of the linear no-threshold (LNT) model of radiation damage, which is the basis of current regulation, and to assess the justification for this regulation. We have conducted an extensive search in PubMed. Special attention has been given to papers cited in comprehensive reviews of the United States (2006) and French (2005) Academies of Sciences and in the United Nations Scientific Committee on Atomic Radiation 2016 report. Epidemiological data provide essentially no evidence for detrimental health effects below 100 mSv, and several studies suggest beneficial (hormetic) effects. Equally significant, many studies with in vitro and in animal models demonstrate that several mechanisms initiated by low-dose radiation have beneficial effects. Overall, although probably not yet proven to be untrue, LNT has certainly not been proven to be true. At this point, taking into account the high price tag (in both economic and human terms) borne by the LNT-inspired regulation, there is little doubt that the present regulatory burden should be reduced.

Keywords: disease risk; hormesis; linear no-threshold model; longevity; low-dose radiation; mortality.

Figure 1.

A, Schematic representation of molecular and cellular mechanisms operating at low- and high-dose radiation exposures. B, Time schedule of pathways involved in radiation-induced adaptive response. HSR indicates heat shock response.

Figure 2.

Sources and distribution of average radiation exposure to the world population. Source: World Health Organization.

Figure 3.

A comparison of the radon concentrations and lung cancer mortality rates in the United States. Left panel: Predicted average indoor radon levels (source: EPA Map of Radon Zones; the version available currently on EPA’s web page is provided with permission of the Radiation Protection Division at the EPA). Right panel: Lung cancer mortality rates by county 2000 to 2009, per 100 000 age adjusted to the 2000 US census (source: Static Maps. National Community Mapping Institute). Available currently on the web page of the National Community Mapping Institute). EPA indicates Environmental Protection Agency.