In Vitro-In Vivo Extrapolation of Toxic Potencies for Hazard and Risk Assessment – Problems and New Developments

Toxicological hazard and risk assessment until today largely rely on animal toxicity data. Animal toxicity tests are performed to identify the toxic effects that a chemical can induce (hazard identification) and to determine the toxic potency, i.e. the quantitative relationship between external exposure level (administered dose, environmental concentration) and the incidence and severity of toxic effects (dose-response assessment). Both components of hazard assessment are essential for toxic hazard classification and labelling, determination of safe exposure levels and, in connection with exposure assessment, for risk assessment (fig. 1). The aim of toxicological risk assessment is to characterise the likelihood, the nature and the severity of adverse effects occurring to man or the environment caused by defined exposure to a chemical. If in vitro methods shall be used for toxicological hazard and risk assessment and for safety evaluation, they must provide information which can be used to reliably assess the kinds of toxic hazards and the corresponding toxic potencies. Despite considerable efforts during the last about 20 years, in vitro methods have only been accepted for hazard identification and classification in a few cases, e.g. in testing for genotoxicity/mutagenicity, acute local skin and eye toxicity and phototoxIn Vitro-In Vivo Extrapolation of Toxic Potencies for Hazard and Risk Assessment – Problems and New Developments