Suchergebnisse

Alternative methods in ecotoxicology play an increasingly important role in chemical and risk assessment. Already in 1986, the Directive 86/609/EEC stated that an alternative method, once it is "practicably and reasonably available", should replace the corresponding animal method. In 2007, REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) came into force to systematically evaluate the risk to human health and the environment of approx. 30,000 chemical substances produced, used or imported in quantities of 1 - 100 t/a. Within the framework of REACH, animal testing should be reduced or even replaced by alternative methods. The 96 h acute fish test, however, is still a mandatory component in the base set of data required for chemical risk assessment. With mortality as the exclusive endpoint, it is not compatible with most current animal welfare legislations in Europe. Furthermore, there is increasing concern that some form of pain perception, similar to what is present in mammals, may be present in bony fish, and adult fish exposed to acute toxic concentrations of chemicals may at least be suspected to suffer severe distress and pain. A promising candidate to replace the acute fish test in chemical assessment is the fish embryo toxicity (FET) test. In Germany, the FET has already replaced the acute fish test in whole effluent testing since 2005. A major advantage of the FET concerning animal welfare is the fact that embryos may have not yet developed the same complex mental processes and may have not pain perception identical to adult fish. Since the correlation between the alternative and the test to be replaced is one of the most important facts to accept a test as alternative, a detailed literature research and a thorough re-evaluation of FET and acute fish test data has been conducted. The analyses resulted in an overall R2 of 0.90 for the comparison of FET data and acute fish test data. Restricting the data to zebrafish (Danio rerio) FET data and all fish data, the correlation resulted in an R2 of 0.87. In general, all correlations with different restrictions of the complete dataset (e.g. only zebrafish FET and zebrafish acute fish test data, only 48 h FET and 96 h fish toxicity data, etc.) showed no R2 lower than 0.81. For comparison between different biotests, these are almost perfect correlations, and compared to correlations of 96 h acute fish data among different fish species, they are in the same range or even better. However, outliers are inevitable. In order to investigate if the static procedure of the FET may be the reason for outliers, a flow-through protocol was developed. The applicability of the flow-through system in chemical assessment was checked by testing four different "outlier chemicals" (hydroquinone, 4-chlorophenol, pyraclostrobin and α-endosulfan), which were selected according to increasing log Pow. Independent of chemical nature and lipophilicity, the flow-through and the static FET gave almost identical results for all substances. Thus, at least for these chemicals, the differences between the results from the FET and the acute fish toxicity test could not be traced back to reduced bioavailability due to adsorption to the polystyrene plates. Further investigations are necessary to identify reasons for the poor correlation between FET and acute fish test results for specific chemicals. However, the static protocol seems to be a sufficient testing procedure and should definitely be used in further chemical assessment.