Stochastic effect

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Stochastic effect
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Stochastic effect - health effects related to a person's exposure to radiation. Frequent in the treatment of diseases such as cancer. However, this cannot be clearly attributed only to the effect of radiation exposure because it is only one of many possible causes of this effect. There are currently no commonplace available biomarkers that are specific to radiation exposure.

The higher frequency of the stochastic effect in the population can be attributed to radiation exposure through epidemiological analysis - provided that, among other things, the increased frequency of this effect was sufficient to overcome the inherent statistical uncertainties[1].

The occurrence of a stochastic effect

A characteristic feature of the stochastic effect is that there is no dose below which the effect does not take place, although the likelihood of carcinogenic or hereditary effects increases with dose.

The stochastic effect may result from the irradiation of one or more cells, and the severity of the response is not dose-dependent. Therefore, the dose absorbed by a limited part of the patient's body does not provide a general perspective on the risks associated with the procedure.

The effective dose is the right amount to take. It includes irradiated tissues and organs, as well as the dose involved. This is important because some tissues and organs are more susceptible to radiation than others.

The definition of the efficient dose is the sum equivalent to each shielded tissue and organs multiplied by the appropriate tissue weighting factors[2].

Types of effects

Radiological studies distinguish two effects: deterministic and stochastic. Deterministic effects hinge on killing many cells in a relatively short time. They are induced by strong exposures, and the result of this exposure is quite well set.

The dose size sets the intensity of the result. The most obvious deterministic result is the victim's death within a short time (several months or less) after exposure.

The effect of radiation exposure from nuclear energy is primarily stochastic. Even in the Chernobyl accident, relatively few workers received sufficiently high doses of acute radiation to cause death within a few months or other deterministic effects.

Many more people were exposed to lower doses. The predicted emergence of cancer in these populations is late, usually by more than 10 years from the time of exposure, and it is not likely to identify specific personal victims[3].

Types of radiation

There are several types of radiation[4]:

  • x-rays and gamma rays - quality factors is 1,
  • electrons (including beta particles) - quality factors is 1,
  • neutrons (depending on energy) - quality factors is between 5-20,
  • alpha particles and fission fragments - quality factors is 20.

These quality factors correspond to the standard values recommended in the International Commission on Radiological Protection (ICRP).


  1. UNSCEAR, (2015), pg. 72
  2. Hall E. J., Giaccia A. J., (2006), pg. 192
  3. Bodansky D., (2007), pg. 87
  4. Bodansky D., (2007), pg. 61


Author: Oliwia Książek