Stochastic effects due to radiation exposure require which of the following?

• A. a minimum threshold dose in order to appear
• B. no minimum threshold dose in order to appear
• C. a minimum amount of time of exposure to appear
• D. both a threshold dose and time of exposure

Answer: (B)

Stochastic effects from radiation are random events that can occur after any amount of exposure; there is no minimum dose required for them to appear. The probability of effects like cancer or genetic changes increases with the total dose, but the severity of those effects isn’t determined by the dose level in the same way as for non-stochastic (deterministic) effects. This is why a linear no-threshold view is used: risk rises with dose even at very low levels, rather than only after crossing a fixed threshold. Time of exposure isn’t a separate trigger for these effects—the total dose, and how it accumulates, drives the probability. In contrast, deterministic effects have clear threshold doses, which is why statements involving a threshold dose don’t apply to stochastic outcomes.