Potential of in Vitro Methods in Ecotoxicological Risk Assessment

Over the years, biota in the environment have seen exposure to an increasing number of anthropogenic chemicals. Public and scientific awareness have led to a growing claim for sound data on the toxicological properties of these environmental substances, in particular since for many if not the majority of environmental chemicals, only limited toxicological data is available. Hence, during recent years several national and international activities have been initiated recently aiming to establish improved approaches for assessing persistence, bioaccumulation and toxicity of both existing and newly developed chemicals. For instance, in Europe the new chemicals regulation REACH (Registration, Evaluation and Authorization of Chemicals) is currently under implementation. In the framework of REACH, environmental hazard data will have to be generated for a huge number of chemical substances. It is obvious that this cannot be achieved by relying exclusively on existing conventional in vivo tests, which are time-consuming and costly, but that the new situation asks for more efficient approaches to environmental risk assessment. As a consequence, intensive efforts are underway aiming to develop integrated testing strategies which take advantage of information often neglected to date, in particular, non-testing information - for instance, from structure-activity relationships - and in vitro testing information. This communication is focusing on the potential utility of in vitro assays as part of a tiered ecotoxicological risk assessment scheme. Examples are provided how results four in vitro data could be used (i) as screening assays generating "toxicological alerts" to prioritize chemicals for further testing and to guide subsequent hazard assessment, and (ii) as alternative to in vivo testing for the assessment of bioaccumulation of xenobiotics by fish.