The History of the Linear No-Threshold Model

NOTE: The American Academy of Health Physics has preapproved 10 continuing education credits for certified health physicists watching all 22 episodes of this video series. Please use the preapproval lookup code: 2022-04-21-185 when submitting your continuing education credits for recertification, after you have watched the series.

The international community is embarking on a review of the entire system of radiation protection. The Health Physics Society (HPS) is contributing to this effort by providing this series of videos that describe the historical foundations of the current protection philosophy based on a linear no-threshold (LNT) model for cancer risk assessment.

One critical aspect of any science is to question and examine how the science thus far has brought us to our current state of understanding. HPS created this series of videos to examine the history of the most controversial question in our field: the LNT model.

In about 10 hours, watching 22 episodes, you will see a story unfold that has not been taught in our academic institutions. One that is backed by 40 years of research by Dr. Edward Calabrese with thousands of documents and publications. A journey that involves Nobel Prize winners, ethical and moral challenges, nuclear fallout, scientific biases, the influence of money on scientific organizations, and the development of government policies.

What you will learn is significant and may even justify a move away from the LNT model for cancer risk assessment and related government policies. 

Please provide comments, questions, counterevidence, or additional supporting documentation to We will provide responses on a twice-monthly basis. If you have questions about radiation not related to these videos, please visit Ask the Experts.

If you are an HPS member, you will also have access to a trove of documentation as an adjunct to the episodes. If you're not yet a member, you may apply to join now.

The views expressed in these videos do not necessarily represent official positions of the Health Physics Society.