safety/ uncertainty factor, also known as assessment factor
Pertaining to a substance, it is a factor used by risk assessors to derive a reference dose that is considered safe or below which an adverse effect is unlikely to occur. The value of the safety factor depends on the toxic effect, the size and type of the population to be protected and the quality of the (eco)toxicological and exposure data available
In food safety, an assessment factor is a safety margin applied when evaluating how much of a substance (like a chemical, contaminant, or additive) people can safely be exposed to. It accounts for uncertainties in the data, such as differences between animals and humans, variation among people, or gaps in experimental studies.
EFSA uses assessment factors to make sure exposure limits are protective for all consumers. For example, if a toxic effect is seen in animals at a certain dose, EFSA may divide that dose by an assessment factor (often 10, 100, or more) to set a safe level for humans.