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(M/FF212) Establishment of an Indoor Higher Tier system for testing of plant protection products in aquatic systems; ecological and regulatory considerations. Duquesne, Sabine1, Wahrendorf, Steffen1, Streloke, Martin2, Heimbach, Fred3, Liess, Matthias1, 1 2 3 ABSTRACT- Agrochemicals are primarily assessed for registration process using various standardised laboratory toxicity tests. When such investigations reveal a possible concern, further evaluations are required to determine potential risks under more realistic conditions in terms of fate and effects. Such studies are currently conducted with multispecies large- scale indoor microcosms or mesocosms. Intermediate tests such as indoor Higher Tier systems considering pesticide sorption, individual interaction and autochton population recovery may be used as an intermediate step in a tiered approach. Indeed they can provide useful information when the selected exposure scenarios and endpoints have ecological significance and relevance. Such a laboratory population experiment was designed to determine the impact of a plant protection product on the population growth and recovery of the aquatic species Daphnia magna. A test substance was chosen for which data from standard tests and a mesocosm were available to facilitate validation of results to be generated in this research project. The changes in number of individuals and in population structure were monitored over several generations using a newly established non-intrusive method using automated image analysing. The toxicity data obtained with slightly different test systems were compared. For the plant protection products used in this study, the standardised single- species laboratory toxicity tests provide data that are significantly lower than in the indoor Higher Tier systems and mesocosms studies. In the laboratory population experiment described, individuals show a sensitivity towards the test substance that is relatively similar to outdoor studies when recovery under laboratory conditions is included. Ecological considerations and regulatory interpretation are discussed for incorporation of Higher Tier system in the regulatory risk assessment framework. Key words: microcosm, population, recovery, toxicity |
