Introduction and General Aspects of Risk Assessment
With the development of the European Union, the development of common toxicological standards was required to remove barriers to inter-community trade, and it has also been thought desirable to have common standards of worker safety and common environmental standards. There are various types of regulatory regimes, including premarketing approval systems and notification schemes. Yet a further type of regulation applies to existing situations, such as air pollution. Here, the main roles of the regulatory regimes are setting standards. Regulation depends on good data, which come from two main sources: proprietary data and studies in the peer-reviewed literature. Both sources have strengths and weaknesses. Proprietary data are generally generated according to good laboratory practice and guidelines are available for the conduct of many regulatory studies. There are a number of instances of retracted papers in the peer-reviewed literature that have had regulatory impact. For many substances, reference doses are calculated from toxicological data, most often obtained from experimental animals, generally by application of an uncertainly factor, or factors, to the lowest relevant no-effect-level in the most sensitive species. Air quality guidelines are predominantly derived from epidemiological data.