Abstract

This report is the final report of a research contract of RIVM in the framework of the Radiation Protection Programme of the Commission of the European Communities. The aim of the project was to investigate the nature of the dose-effect relationship for radiobiological effects after different types of ionizing radiation and UV. The results of the contract support the idea that the linear-quadratic dose relationship for radiobiological effects does reflect a two-hit or two-event type of radiation effect. The track structure calculations of the linear term indicate that the DNA double-strand break could be the crucial lesion and that the two simultaneous events should occur close to each strand of the DNA molecule in a single track. The experimental data indicate that the quadratic term arises from the combination of two time independently induced events the role of which can be modified by repair but these data do not provide any information on the nature of the radiation induced lesions.