Non-Stochastic effects are defined as having a threshold for risk from exposure.

• A. True
• B. False
• C. They have no threshold
• D. They are dose-insensitive

Answer: (A)

Non-stochastic (deterministic) effects show a dose threshold. Below a certain dose, these effects don’t occur or are not observable because the tissue repair processes cope with the damage. Once that threshold is surpassed, the probability of seeing an effect becomes significant and the severity of the effect generally increases with the dose. This is why there is a defined threshold for these effects, such as skin erythema, cataracts, or acute radiation syndrome at high doses. So the statement that non-stochastic effects have a threshold for risk is correct. In contrast, stochastic effects (like cancer) are considered to have no clear threshold, and their risk rises with dose. Being dose-insensitive would imply no effect at all, which isn’t accurate for non-stochastic effects above their threshold.