Stochastic effects are defined as having no threshold for risk from exposure.

• A. True
• B. False
• C. They have a threshold
• D. They are dose-insensitive

Answer: (A)

Stochastic effects are modeled with a non-threshold dose–response: any amount of radiation carries some small probability of causing the effect, so the risk increases with dose even at very low exposures. That’s why the statement is true—the risk is not thought to have a finite minimum dose where it begins.

In this framework, the chance of occurrence rises with dose (often described as linear with dose at low levels), while the severity of the effect, if it occurs, is not determined by the dose. This helps distinguish stochastic effects (like cancer or genetic effects) from deterministic effects, which do have a threshold and become more severe with higher doses.

The other options don’t fit because they imply a threshold exists, or that there is no dose–response at all.