Special Issue Introduction

Abstract

Ionizing radiation protection regulations for humans are based on the presumption that any amount or radiation, no matter how small, will cause cancer in a very large population. The regulations impact on the use of ionizing radiation in routine diagnostic procedures (e.g., computed tomography), on allowable radiation levels in the environment (e.g., residential radon levels), and on allowable radiation exposures in the workplace (e.g., nuclear facilities). Cancer risks evaluations are based on the linear-no-threshold (LNT) paradigm for which risk is assumed to increase linearly as the radiation dose increases (Puskin 2009 Justification for the continued use of the LNT risk model is based largely on results from epidemiological studies that employ inappropriate methods (Scott et al. 2008) such as the following: (1) giving considerable weight to high-dose, high-dose-rate data where excess cancers clearly occur while ignoring the absence of excess cancers after low doses and dose rates; (2) dose lagging (i.e., discarding some of the dose thereby shifting the dose-response curve to the left, making smaller doses appear more harmful than they actually are); (3) attributing observed low-doseassociated reductions in the cancer incidence among radiation workers to a presumed healthy worker effect; (4) not allowing for the possibility that a threshold or a reduction in risk at low doses may occur because of radiation-stimulated adaptive protection; and (5) averaging over wide dose intervals so that nonlinearity is removed.This issue provides additional support for the rapidly growing view that the LNT risk model should not be used for low-dose cancer risk assessment. The paper by Fornalski and Dobrzyński (2010) discusses the inappropriate use of the healthy worker effect assumption in attempts to