[The concept of synergism in radiobiology]

The definitions and various quantitative estimations of synergistic effects are presented. Common regularities of synergistic interaction under combined action of different harmful environmental agents are summarized. Possible mechanisms and mathematical models for prognosis and optimization of the synergistic effect are discussed. The data related with the dependence of synergy on intensity of agents applied are analysed. On this basis, it is concluded the fundamental importance of synergistic interaction at low dose rate of ionizing radiation and/or low intensity of UV light.