The cancerogenicity of fall out nuclides

One of the more than 400 radionuclides which are produced in a nuclear reactor only a few of these have features such as solubility, long physical and biological half life and specific affinity to a certain tissue - which could classify them as biologically hazardous. Therefore in this context only radio-iodine-cesium and -strontium are discussed briefly as regards their biological effects. It is pointed out that tumours are not easily induced by radioiodine in experimental systems and that this is also valid for humans. Radiocesium is not very extensively studied experimentally as regards its biological action but available data indicate a low - if any - cancerogenic potentiality in contrast to radiostrontium with its high yield of tumours in various tissues. The extrapolation of experimental data to man as well as a comparison between cancerogenic irradiation doses between man and animals are discussed and considered as a necessity because of the ill defined irradiation situation and data which are connected with most accidental exposure of man. Furthermore it is also pointed out that the general idea that irradiation risks always are represented by a linear dose-effect relationship in most cases has no support from scientific data and therefore give an overestimation of the true risk. This should not be considered as a plea for the abandonment of the 'linear philosophy' but it is necessary to point out that as long as other environmental risks are calculated in a more liberal way, irradiation will always be victimized and discriminated against in the large flora of environmental dangers. The necessity of giving a clear reference to the spontaneous incidence of tumours during the time covered by the calculation must also be presented as well as that the estimate is founded on a hypothesis which is not scientifically proven. (author)