Biomedical principles for intervention in the event of a serious accident

The principles of public protection in the event of an accident are well-defined. The establishment of reference levels for each public protection measure, whatever the reference system chosen, requires the best possible knowledge of the effects likely to appear in the population open to exposure. Non-stochastic effects are seen in well-defined organs or tissues: bone marrow, lungs, thyroid and skin, and, where pregnant women suffer exposure, also the foetus. The shape of the dose-effect curves for most of these organs is, in general, sufficiently well known, as are the thresholds at which the effects appear. Nevertheless, the degree of uncertainty in the threshold doses (the doses responsible for 50% and 100% of the effects) are, in certain cases, of the same order of magnitude as the LD0-LD100 interval. These differences make it difficult to give a quantitative prognosis for the likelihood of survival in a population which may be exposed within the dose range proposed for LD 50/60. However, there is no doubt that the data needed for correct decisions do not need to be refined or to include all the known facts about the pathology of an organ or system. The main thing is to know the dose levels below which, in a normal population, the probability of non-stochastic effects appearing is practically zero. These are the threshold doses on which the authorities will base their choice of reference levels for implementing protection measures. (author)