Review ArticlesThe Birth of the Illegitimate Linear No-Threshold Model An Invalid Paradigm for Estimating Risk Following Low-dose Radiation ExposureSiegel, Jeffry A. PhD*; Pennington, Charles W. MS, MBA†; Sacks, Bill PhD, MD‡; Welsh, James S. MS, MD, FACRO§Author Information *Nuclear Physics Enterprises, Marlton, NJ †NAC International, Norcross, GA ‡Emeritus Medical Officer, FDA Center for Devices and Radiological Health, Rockville, MD §Department of Radiation Oncology, Stritch School of Medicine Loyola University Chicago, Maywood, IL The authors declare no conflicts of interest. Reprints: James S. Welsh, MS, MD, FACRO, Department of Radiation Oncology, Stritch School of Medicine Loyola University Chicago, 2160S 1st Ave, Maguire Center, Rm 2932, Maywood, IL 60153. E-mail: email@example.com. American Journal of Clinical Oncology: February 2018 - Volume 41 - Issue 2 - p 173-177 doi: 10.1097/COC.0000000000000244 Buy Metrics Abstract This paper examines the birthing process of the linear no-threshold model with respect to genetic effects and carcinogenesis. This model was conceived >70 years ago but still remains a foundational element within much of the scientific thought regarding exposure to low-dose ionizing radiation. This model is used today to provide risk estimates for cancer resulting from any exposure to ionizing radiation down to zero dose, risk estimates that are only theoretical and, as yet, have never been conclusively demonstrated by empirical evidence. We are literally bathed every second of every day in low-dose radiation exposure due to natural background radiation, exposures that vary annually from a few mGy to 260 mGy, depending upon where one lives on the planet. Irrespective of the level of background exposure to a given population, no associated health effects have been documented to date anywhere in the world. In fact, people in the United States are living longer today than ever before, likely due to always improving levels of medical care, including even more radiation exposure from diagnostic medical radiation (eg, x-ray and computed tomography imaging examinations) which are well within the background dose range across the globe. Yet, the persistent use of the linear no-threshold model for risk assessment by regulators and advisory bodies continues to drive an unfounded fear of any low-dose radiation exposure, as well as excessive expenditures on putative but unneeded and wasteful safety measures. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.