Which statement about nonstochastic effects is true?

• A. They occur only if the dose exceeds a fixed minimum.
• B. They are inherited genetic effects.
• C. They occur with no dose relationship.
• D. They have a threshold and severity increases with dose.

Answer: (D)

Nonstochastic (deterministic) effects have a definite dose threshold: below that dose, no effect is seen, and once you cross it, the harm increases as the dose increases. That makes the statement about having a threshold and severity increasing with dose the true description. In dental radiology, tissue reactions would appear only after surpassing a certain absorbed dose, and higher exposures would produce more severe effects. The idea that effects appear only above a fixed minimum ignores how the damage scales with dose beyond that point. Genetic or inherited effects aren’t the defining feature of nonstochastic outcomes, and effects with no dose relationship describe stochastic effects, where probability rises with dose but severity is not dose-dependent.