[Mechanism of the primary radiobiologic action]

Basing on the well-known high sensitivity of the biological processes to alteration of pH of a medium it is assumed that one of the major factors of primary biological effect of ionizing radiation is the increase of acidity in charged particle's tracks. This makes possible to understand the mechanism of protective action of various radioprotectors and the extremal experimental dependence of RBE vs LET has been explained. The position of corresponding maximum was estimated as approximately 10 eV/A in accord with experimental data.