BENEFICIAL RADIATION

Ionizing radiation is harmful and may cause cancer, as is well known. However, again and again, low doses of ionizing radiation, under certa in conditions, are said to have beneficial effects on human health and , in particular, may reduce the cancer rate. This effect, which is dis cussed controversially in the technical and scientific literature, is called ''hormesis''. Studies of possible positive effects of ionizing radiation are becoming increasingly more important in scientific resea rch. The article is an attempt to show, by the model case of cancer, u nder what conditions such positive health effects can occur, at least in principle, and will also contain rough plausibility assessments of the existence of such conditions. Aspects not covered include other ex isting or presumed positive biological effects of ionizing radiation, such as acceleration of growth, or general increase in the life expect ance of organisms. Also genetic damage will not be discussed in greate r detail, despite the existence of some parallels with cancer,, both c ases constituting lesions to the genetic material of th cells, in one case, germ cells and, in the case of cancer, somatic cells. Also acute radiation effects will be excluded which occur only at high radiation doses and, as such, always cause damage which, in therapeutic applica tion to cancer, may again be lifesaving. It should be emphasized that the article is limited to a greatly restricted range of biological eff ects of ionizing radiation which, consequently, are limited value for overall assessment.