These effects are also called random or probabilistic effects.

Stochastic effects mainly consist of cancer and leukaemia, which may appear a few years or several decades after the exposure.

These effects are probabilistic (i.e. they are governed by chance): in an exposed population, they do not systematically affect every person and there is no way of predicting who will be affected. Furthermore, when cancer cases occur, it is impossible to say which ones were induced by radiation.

In other words, the severity of stochastic effects does not depend on the level of exposure: a person either has cancer or does not. It is the frequency of cancer cases in the exposed population that increases with the dose.