What are stochastic and nonstochastic effects of radiation exposure?
There are two types of adverse effects from radiation exposure: nonstochastic (also known as deterministic) and stochastic (also known as probabilistic). Nonstochastic effects are nonprobabilistic.
Stochastic effects have been defined as those for which the probability increases with dose, without a threshold.
Nonstochastic effects are those for which incidence and severity depends on dose, but for which there is a threshold dose. These definitions suggest that the two types of effects are not related.
By comparison, stochastic effects are probabilistic. The probability of the occurrence of a stochastic effect is greater at higher doses of radiation exposure, but the severity of the effect is similar whether it occurs from exposure to more or less radiation.
The two categories of stochastic effects include cancer induction and genetic mutation.
Stochastic effects are not presently believed to have a specific exposure threshold, although this is a subject of debate.
