Effects on the central nervous system after combined exposures: General considerations

The interaction between a radiation event and the effects of chemical substances in generally based on specific mechanisms. Apparently modifications of recovery and proliferative processes are very important for supra-additive effects after combined exposures. The combination of ionizing radiation with chemical carcinogenic 'initiators' generally yields no supra-additive effects on total tumour incidence rates. Studies of mechanisms, of time sequences, and of dose effects curves are necessary after combined exposures to ionizing radiation and chemicals in order to evaluate possible supra-additive effects. (orig.)