Development of methods for evaluating toxicity to freshwater ecosystems

This article presents a summary of a collaborative research program involvi ng five European research groups, that was partly funded by the European Co mmission under its Environmental Research Program. The objective of the pro gram was to develop aquatic toxicity tests that could be used to obtain dat a for inclusion at Level 2 of the Risk Evaluation Scheme for the Notificati on of Substances as required by the 7th Amendment to EC Directive 79/831/EE C. Currently only a very limited number of test methods have been described that can be used for this purpose and these are based on an even smaller n umber of test species. Tests based upon algae (Chlamydomonas reinhardi, Sce nedesmus subspicatus, and Euglena gracilis), protozoa (Tetrahymena pyriform is), rotifera (pyriformis calyciflorus), crustacea (Gammarus pulex), and di ptera (Chironomus riparius) were developed. The tests encompassed a range o f end points and were evaluated against four reference chemicals: lindane, 3,4-dichloroaniline (DCA), atrazine, and copper. The capacity of the tests to identify concentrations that are chronically toxic in the field was addr essed by comparing the effects threshold concentrations determined in the l aboratory tests with those determined for similar and/or related species an d end points in stream and pond mesocosm studies. The lowest no-observed-ef fect concentrations (NOEC), ECx, or LCx values obtained for lindane, atrazi ne, and copper were comparable with the lowest values obtained in the mesoc osms. The lowest chronic NOEC determined for DCA using the laboratory tests was approximately 200 times higher than the lowest NOEC in the mesocosms. (C) 2000 Academic Press.