Which term describes biological effects that occur by chance, are not clearly tied to radiation exposure, and include primarily cancer and genetic effects?

• A. Acute effects
• B. Stochastic effects
• C. Nonstochastic effects
• D. Subclinical effects

Answer: (B)

Biological effects described as stochastic are random, probabilistic outcomes whose likelihood rises with dose but whose occurrence for any given individual is by chance. The classic examples are cancer and heritable genetic effects, which are not tied to a specific threshold in a way that guarantees an effect for an exposed person. Instead, risk increases with dose across the population, and the exact outcome for an individual is unpredictable. In contrast, deterministic (acute) effects have definite thresholds and their severity grows with dose, and subclinical effects are those that are not outwardly evident. So the term that best fits these chance-based, primarily cancer and genetic outcomes is stochastic effects.