Influence of the initial spatial distribution of radical species in irradiated water on their subsequent diffusin, reactions and attack on DNA

In the framework of the improvements of the biophysical simulation code PARTRAC, we have started a critical review relative to the models of the formation, diffusion and reaction of water radicals. The simulation of indirect DNA damage includes the production of water radicals after radiation insult (based on the cross sections of water and other cellular constituents), the diffusion and reaction of radicals (controlled by a set of parameters describing the diffusion and the reaction properties of each radical species) and the reaction of radical species (mainly the hydroxyl radical) with the DNA molecule. Some uncertainties still characterize cross-section data for the liquid phase, and the chemical processes determining induction of lesions by OH radicals are not fully understood. It is thus of great interest to quantify to what extent such uncertainties propagate through the complete process of DNA damage.