On Facilitating the End of the Linear No-Threshold Era

TO THE EDITOR: In a recent editorial piece, Doss proposes a mechanism to definitively settle the issue of the linear no-threshold (LNT) hypothesis versus radiation hormesis (1). Among the reasons given to settle the issue, the author mentions that a rejection of the LNT hypothesis in favor of radiation hormesis by the scientific and regulatory communities “could significantly reduce cancer mortality rates and streamline radiation safety regulations, fostering medical innovation and economic growth” (2). Doss correctly points out that a role of the scientific community is to continuously test hypotheses, eliminating those incompatible with accumulating evidence—especially when these hypotheses carry significant public health implications. The author then makes the remarkable affirmation—with economy of evidence—that a rejection of the LNT hypothesis in favor of hormesis “would [bold is mine] have translated to preventing nearly 2 million cancer deaths in 2022 alone” (3–5).

Personal viewpoints and positions aside, Doss proposes the following resolutive mechanism: “a public, online debate between supporters of the LNT model and advocates of radiation hormesis…organized by a government agency.” He follows up with “the arguments and counterarguments would be conducted transparently in the public domain, ensuring that interested parties can access the reasoning and evidence presented and call out any invalid arguments.” But I ask: who exactly would be the arbiter or arbiters of this “debate”? What exact mechanism would these arbiters use to decide which side wins? How would the arbiters themselves be vetted, given that many experts in radiobiology or health physics already have a personal viewpoint on the matter and are therefore ab initio biased?

In his closing argument, Doss—who appears to be a proponent of hormesis—claims that if the LNT hypothesis is rejected and hormesis is instead adopted as a basis for regulatory standards “there would be a decrease in jobs related to radiation safety…[However,] the emergence of new job opportunities in supporting applications of low-dose radiation in medicine would more than offset this decline.” The author does not point to any supporting evidence justifying this extraordinary claim, such as peer-reviewed financial forecasting or economic modeling of some type.

In summary, Doss proposes a meritorious but imperfect road map to settle a chronic issue that has been nagging at the radiologic and health physics community since at least 1958, when Brues pointed out that the relation between dose and effect on human leukemogenesis did not support a linear relation (6). Doss’ proposal—as articulated—is incomplete; it presents substantial implementation difficulties, and it leaves significant questions unanswered. With further work to address some of the issues mentioned, the ideas proposed by Doss may indeed prove to be a viable starting point on the path toward finally resolving this issue.

• © 2025 by the Society of Nuclear Medicine and Molecular Imaging.

• Received for publication October 25, 2024.
• Accepted for publication October 31, 2024.