Guidance Risk characterisation methods


1. This guidance statement provides an overview of the approaches to characterising the risks associated with exposures to chemical carcinogens. It is part of a series of guidance statements by the Committee on Carcinogenicity of Chemicals in Food, Consumer Products and the Environment (COC) and should be read in conjunction with these, and in particular G01, G02 (Synthesising Epidemiology Evidence Subgroup (SEES) Report), G03 (Hazard identification and characterisation: conduct and interpretation of carcinogenicity studies), G05 (Points of departure and potency estimates) and G09 (COC set of principles for consideration of risk due to less than lifetime exposure).

2. Risk characterisation is the fourth stage of the risk assessment paradigm and brings together the hazard identification and characterisation stages and the exposure assessment process. For carcinogenic effects, the risk characterisation approach used depends on the mechanisms of carcinogenicity and the relationship between dose and carcinogenic response. For most non-genotoxic carcinogens, it is accepted that there is a threshold dose, below which no effect is observed.

In contrast, for compounds which are genotoxic and carcinogenic and for which there are no mechanistic data to suggest a threshold for genotoxicity, or for substances where no mode of action or threshold for effect has been identified, it is currently considered prudent to assume that no threshold for carcinogenicity exists. The processes of hazard identification and hazard characterisation are therefore key to determining the approach to be taken in risk characterisation.

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UK HSE, 25-08-22