Aims and mission of regulatory toxicology

Abstract

The aim of regulatory toxicology is to control production, use, and deposition of dangerous materials to prevent adverse effects on human health and the environment. This requires sufficient information on the hazardous properties of a chemical compound, their relevance to man and of human and environmental exposure, which is a prerequisite for appropriate risk assessment and the decision whether regulatory consequences are warranted. The three elements of risk assessment of chemical substances are hazard identification, evaluation of dose–response relationship, and exposure assessment. The risk assessment process requires differentiation between reversible and irreversible effects, i.e., identification of a NOAEL and/or a LOAEL for the most critical effect of the substance, or, in the latter case, estimation of the risk of an exposure. The margin of exposure (MOE) or margin of safety (MOS) can be calculated by comparing the NOAEL with the human exposure. In general, up to now the risk of genotoxic carcinogens at a certain exposure concentration is estimated by linear extrapolation of the dose–response curve. Additional information for the evaluation of the human relevance of experimental data may be available from toxicokinetics or the mode and/or mechanism of action. By setting, for example, limit values like ADI or DNELs or implementing risk management measures, the uncertainties of the database on chemical substances have to be taken into consideration. Another challenge is the evaluation of mixtures. The systems for classification used by various national and international institutions are summarized. The use of the so-called precautionary principle and of the “Threshold of Toxicological Concern” (TTC) concept for risk assessment purposes is explained. In addition, the regulations for specific chemical classes like drugs or pesticides are completed by a short description of the EU REACH regulation for chemical substances.