Principles for a pragmatic approach to the regulatory acceptance of alternative tests

Toxicity studies are conducted with a view to identifying and assessing human or environmental hazards. Thus, the key issues are those of which, and how much, information is considered necessary to make a reliable and valid assessment, and to what extent alternative tests can contribute to this assessment. In this respect, the following fundamental aspects are of relevance. Toxicology as a science focuses on the identification and characterization of adverse effects following exposure to chemicals by integrating all available information, including physicochemical properties, all observed adverse effects in all studies, toxicokinetics and toxicodynamics, exposure conditions, and more. Most of this information is generated in tests conducted according to internationally accepted guidelines. Next, the art of toxicology is to evaluate and extrapolate the information acquired and then to assess human and environmental health hazards. Thus, the validity of any hazard prediction relies both on the collected data and on the craftsmanship of the assessor. Unfortunately, the experts involved in the science of toxicology are frequently not involved in the art of toxicology. As a consequence, the artist who is used to his set of fine tools, which he bought a long time ago and with which he always managed to create the 'sculpture' of hazard assessment, is now suddenly asked to use some new and rather different tools. It is understandable that this may bring about some opposition. In addition to these fundamental aspects, there are also political aspects to the issue of acceptance of alternative tests. These and other pitfalls have contributed to the author's opinion that progress in this respect can only be made by introducing the alternative tests without, at least for the time being, deleting the trusted existing ones.