Radiation hormesis

Radiation hormesis (also called radiation homeostasis) is the hypothesis that low doses of ionizing radiation (within the region of 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.

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 the 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 effective dose of 100 millisieverts may increase cancer risk by ~0.8%. However, children are particularly sensitive to radioactivity, with childhood leukemias and other cancers increasing even within natural and man-made background radiation levels (under 4 mSv cumulative with 1 mSv being an average annual dose from terrestrial and cosmic radiation excluding radon which primarily doses the lung). There is also indication that exposures around this dose level will cause negative subclinical health impacts to neural development. Students born in regions of Sweden with higher Chernobyl fallout performed worse in secondary school, particularly in math. “Damage is accentuated within families (i.e., siblings comparison) and among children born to parents with low education..." who often don't have the resources to overcome this additional health challenge.

Hormesis remains largely unknown to the public. Any policy change ought to consider hormesis first as a public health issue (versus an industrial regulatory issue). This would include the assessment of the public concern regarding exposure to small toxic doses. In addition, impact of hormesis policy change upon the management of industrial risks should be studied. Government and regulatory bodies disagree on the existence of radiation hormesis and research points to the "severe problems and limitations" with the use of hormesis in general as the "principal dose-response default assumption in a risk assessment process charged with ensuring public health protection."

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