Assessment of the genetic risk in man exposed to ionizing radiation

Assessment of the radiation-induced genetic risk in man has to be done by applying the results of animal experiments to man. The dose-response relationships determined with mice show that there is no zero-risk threshold with respect to induction of mutation. The quantitative determination of radiation-induced, dominant mutations is the basis for direct assessment of the genetic risk. Indirect assessment relies on the method of the doubling dose which is tested in animal experiments, usually with mice. Other data used for risk assessment are taken from research results in human genetics. Risk assessment on the basis of gene number is not possible as the number of genes in man is unknown, so that the only possible approach is to assess the mutations of the X-chromosome. The genetic risk as a consequence of the Chernobyl reactor accident is assessed and explained, referring to the uncertainties involved in such assessment. The chemogenetic risk as an additional aspect is also briefly discussed. (MG)