Hazard: can it?
IARC calls an agent a cancer hazard if it is capable of causing cancer under some circumstances. A hazard is a property of the agent, regardless of how much of it anyone is exposed to.
Risk: how likely?
Risk is the probability that cancer will occur at a given level of exposure. It depends on how much, how often and for how long. IARC does not evaluate risk; that is done by other bodies. For food additives, for example, it is the work of the joint FAO/WHO Expert Committee on Food Additives (JECFA).
Why it matters
A hazard classification does not establish a safe intake. Separate risk assessments can evaluate risk at specific exposure levels; for example, JECFA set aspartame’s acceptable daily intake at 0–40 mg per kilogram of body weight. The case of aspartame, described on Aspartame, meat and the news, shows both evaluations side by side.
Sources
- IARC, IARC Monographs on the Identification of Carcinogenic Hazards to Humans: Questions and Answers (PDF)
- WHO, Aspartame hazard and risk assessment results released (14 July 2023)
Sources checked on: 1 November 2026