Deterministic effects are characterized by which of the following?

• A. Have no threshold
• B. Severity independent of dose
• C. Have a threshold and severity increases with dose
• D. Occur only at extremely high doses

Answer: (C)

Deterministic effects are those that only occur after a certain dose is exceeded, and their severity grows as the dose increases. This threshold behavior is what sets them apart from stochastic effects, where the chance of occurrence rises with dose but there isn’t a fixed cutoff for when the effect appears. In deterministic effects, different tissues have different thresholds, and once you pass that threshold, more dose means more damage and more severe symptoms. Examples include skin erythema, cataracts, and hair loss—each with a tissue-specific threshold and dose-dependent severity. Saying there’s no threshold or that severity is independent of dose would be incorrect, and claiming they occur only at extremely high doses ignores the tissue-specific thresholds that can be reached at a range of exposure levels.