The radiological risk: uncertainty related to low dose exposure

High doses are rare and exceptional, essentially related to accidental situation, military action, or to medical application for which the expected detrimental effect is targeted to eliminate the tumour. There is no doubt about radiation biological effect at high doses. Such effects for which a clear dose-effect relationship exists are called deterministic effects. Radioprotection policy must prevent any occupational exposure from high doses. At low dose, whatever the low dose received, if a cancer should appear, the severity of the effect is not questionable and it is the probability of having the effect which becomes of concern. Such effects are called probabilistic or stochastic. What are the risks at low dose? The uncertainty of the risk in the low dose exposure range leads toward the application of the precautionary principle as supported by the LNT hypothesis.