Which of the following is categorized as a non-stochastic (deterministic) effect?

Non-stochastic (deterministic) effects are those health effects that occur after a certain threshold of exposure to radiation and have a clear relationship between the dose and the severity of the effect. Erythema, which is reddening of the skin, is classified as a non-stochastic effect because it occurs only after a specific dose of radiation has been exceeded. It can manifest after a significant exposure and tends to worsen with increasing dose, demonstrating a direct and predictable correlation between the radiation dose and the skin reaction.

In contrast, skin cancer, leukemia, and genetic mutations are stochastic effects. These effects can occur without a threshold level of radiation exposure and their probability of occurrence increases with dose, but the severity does not depend on the dose. In other words, just because someone receives a low level of exposure does not mean they will experience milder effects; the occurrence is more probabilistic. This distinction is critical in radiological protection and in understanding how different types of radiation exposure can impact health.