Stochastic radiation effect

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Effects of ionizing radiation, whereby the probability of their occurrence, but not their severity is a func-tion of the dose without the existence of a threshold value. Non-stochastic effects, today called deter-ministic radiation effects, are those in which the severity of the effect varies with the dose and for which a threshold value exists. In the dose range relevant for radiation protection purposes, inheritable damage, cancer and leukaemia belong to stochastic radiation damages. The probability that stochas-tic radiation damage will occur differs widely for the irradiated individual organs or tissues. The Interna-tional Commission on Radiological Protection (Publication 103, 2007) indicates a value of 5.5 % per sievert for cancer and 0.2 % per sievert for heritable effects after exposure to radiation at low dose rate.

The following calculation is designed to illustrate this value: the natural radiation exposure of 2.1 mSv/year in Germany results in a total dose of 172 000 Sv for the approximately 82 million inhabi-tants. If this value is multiplied by the aforementioned risk factor of 5.5 % per sievert for cancer mortal-ity, 9 500 cancer deaths annually by natural radiation result on a calculatory basis.

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