In Europe, the European Food Safety Authority aquatic guidance document describes the procedures for the derivation of regulatory acceptable concentrations (RACs) for pesticides in edge-of-field surface waters on the basis of tier-1 (standard test species), tier-2 (geometric mean and species sensitivity distributions [SSDs]), and tier-3 (model ecosystem studies) approaches. In the present study, the protectiveness of such a tiered approach was evaluated for fungicides. Acute and chronic RACs for tier-1 and tier-2B (SSDs) were calculated using toxicity data for standard and additional test species, respectively. Tier-3 RACs based on ecological thresholds (not considering recovery) could be derived for 18 fungicides. We show that tier-1 RACs, in the majority of cases, are more conservative than RACs calculated based on model ecosystem experiments. However, acute tier-2B RACs do not show a sufficient protection level compared with tier-3 RACs from cosm studies that tested a repeated pulsed exposure regime or when relatively persistent compounds were tested. Chronic tier-2B RACs showed a sufficient protection level, although they could only be evaluated for 6 compounds. Finally, we evaluated the suitability of the calculated RACs for 8 compounds with toxicity data for fungi. The comparison shows that the current RACs for individual fungicides, with a few exceptions (e.g., tebuconazole), show a sufficient protection level for structural and functional fungal endpoints. However, more data are needed to extend this comparison to other fungicides with different modes of action. Environ Toxicol Chem 2019;38:2279–2293.
- Monte de Caparica
- Ecological risk assessment
- Laboratory single-species tests