General Introduction

Abstract

No substance is without poison. Only the dose limits the extent of the poisonous action. This famous quote from the medieval physician Paracelsus is the basis of risk assessment. Risk assessment, in the context of regulation, consists of several pillars, including hazard identification, hazard assessment and exposure assessment, followed by risk characterisation and risk communication. The development of toxicology as a scientific discipline has been dominated for a long time by the assessment of the hazards, which is identification of the toxicological characteristics expressed as toxicological endpoints (see Sect. 2.2.2) of a substance. Hazard assessment characterises the toxicological properties and the corresponding toxic doses of a chemical agent, which, however, cannot be modified. This is quasi “genetically” determined and limited. The only element that controls toxicity is the current dose by which a person is exposed. Therefore, exposure assessment, which is dose evaluation, has become an important pillar of risk assessment. Exposure assessment results play a primary role in the risk communication occurring when the risk assessment results are discussed between the different stakeholders. Many handbooks and guidance documents have been published about exposure assessment, but there is no publication covering the complexity and the different aspects of exposure assessment and their interdependencies.