L'histoire de la radioprotection, un antécédent du principe de précaution

The story of radioprotection all along the XXth century has carried out the progressive building of a protection regime that, very early, incorporated a precautionary attitude in relation with possible risks for health that were still highly uncertain on a scientific ground. Years after such attitude took the form of several complementary principles: justification of any exposure, limitation of doses exposure below thresholds fixed on the basis of knowledge of proven damage for health, be they deterministic or stochastic, and ALARA in order to take account of potential risks resulting from very small doses.To manage the latter, it has been necessary to go out of the strictlty sanitarian domain and integrate economic and socio-political factors. Efforts to reach formal optimisation with the help of cost-benefit analysis, in which strong hopes had been placed at times, did not allow to achieve the expected progress in decision-making and safety and had to be supplemented by pragmatic approaches aimed at involving concerned workers and employees as much as possible in order to reach the lower level of exposure, taking account of economic and social factors. This ALARA approach (procedures and culture) to-day raises an open-ended question about social procedures and economic conditions of sharing a commitment to an accepted exposure to a residual stochastic risk, since zero risk is acknowledged not to exist.