Radiation Hormesis

Radiation hormesis (also called radiation homeostasis) is the hypothesis that low doses of ionizing radiation (within the region and just above natural background levels) are beneficial, stimulating the activation of repair mechanisms that protect against disease, that are not activated in absence of ionizing radiation. The reserve repair mechanisms are hypothesized to be sufficiently effective when stimulated as to not only cancel the detrimental effects of ionizing radiation but also inhibit disease not related to radiation exposure (see hormesis). This counter-intuitive hypothesis has captured the attention of scientists and public alike in recent years.

Quoting results from a literature database research, the Académie des Sciences — Académie nationale de Médecine (French Academy of Sciences — National Academy of Medicine) stated in their 2005 report concerning the effects of low-level radiation that many laboratory studies have observed radiation hormesis. However, they cautioned that it is not yet known if radiation hormesis occurs outside the laboratory, or in humans.

While the effects of high and acute doses of ionising radiation are easily observed and understood in humans (e.g. Japanese Atomic Bomb survivors), the effects of low-level radiation are very difficult to observe and highly controversial. This is because baseline cancer rate is already very high and the risk of developing cancer fluctuates 40% because of individual life style and environmental effects, obscuring the subtle effects of low-level radiation. An acute dose of 100 mSv may increase cancer risk by ~0.8%.

Consensus reports by the United States National Research Council and the National Council on Radiation Protection and Measurements and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) argue that there is no evidence for hormesis in humans and in the case of the National Research Council, that hormesis is outright rejected as a possibility. Therefore, the Linear no-threshold model (LNT) continues to be the model generally used by regulatory agencies for human radiation exposure.