What is a key difference between stochastic and non-stochastic effects?

Stochastic effects are characterized by their probabilistic nature, meaning that their occurrence is tied to exposure to radiation but does not have a definite threshold. This means that even small doses of radiation can increase the risk of developing these effects, such as cancer, over time. The likelihood of these effects increases with the dose but is not guaranteed after any specific exposure, leading to the concept that every exposure carries some risk, no matter how low.

On the other hand, non-stochastic effects, also known as deterministic effects, typically have a clear threshold level of exposure. Below this threshold, the effects are unlikely to occur, while above it, the severity of the effect is correlated with the dose. These effects often manifest as immediate health impacts, such as radiation burns or acute radiation sickness, making their predictability quite different from stochastic effects.

Thus, the distinguishing feature that supports the correctness of the answer is the absence of a lower threshold for stochastic effects, indicating that any amount of exposure carries a risk, albeit a small one.