[Radiations and public health (author's transl)]

A short review is made of the general characteristics of electromagnetic and corpuscular radiations to which man can be exposed. Following some considerations on the action of ionizing radiations and the radiobiological factors governing their effects on health, the overall characteristics of pathological effects differentiating stochastic from non-stochastic effects are summarized. The uncertainties remaining as to low-level exposures are stated as well as the cautious assumptions usually madein this field. The various sources of exposure to which the population is submitted are considered, i.e. exposures from natural, medical, domestic, industrial sources or from fallout from nuclear weapon tests; the present or predictable levels of exposure and their variations are given for each source. But for medical irradiation, all the exposures connected to human activities are much lower than natural exposure variations; such exposures should modify the incidence of certain affections but quite insignificantly as compared with the regional or local variations observed.