Which scenario best illustrates a stochastic effect?

• A. Acute radiation syndrome within hours of exposure.
• B. Developing cancer with no clear threshold; probability increases with dose.
• C. Local tissue fibrosis with a threshold.
• D. Skin erythema that occurs at a defined dose.

Answer: (B)

Stochastic effects are probabilistic: there is no definite dose below which the effect cannot occur, and the chance of occurrence grows with the dose. Cancer fits this best because there isn’t a clear threshold; the probability of developing cancer increases as radiation dose increases, with variability in latency and individual susceptibility.

In contrast, the other scenarios illustrate deterministic effects, which have dose thresholds and tend to become more severe as dose increases. Acute radiation syndrome, local tissue fibrosis, and skin erythema all occur after crossing a certain dose, with a more pronounced response at higher exposures.