Scientific Opinion on the effect assessment for pesticides on sediment organisms in edge‐of‐field surface water

Abstract

The EFSA Panel on Plant Protection Products and their Residues (PPR Panel) was tasked to revise the Guidance Document (GD) on Aquatic Ecotoxicology under Council Directive 91/414/EEC (SANCO/3268/2001 rev. 4 (final), 17 October 2002. This scientific opinion of the PPR Panel is the second of three requested deliverables within this mandate. The scientific background for the risk assessment on sediment organisms in edge-of-field surface waters is provided, with reference to benthic ecology and ecotoxicology, available test protocols and current knowledge on exposure and effects of sediment-bound plant protection products (PPPs). The scientific opinion provides approaches on how to derive regulatory acceptable concentrations (RACs) for sediment organisms and exposure to active substances of PPPs and transformation products of these substances, and how to link them in a tiered approach to predicted environmental concentrations (PECs) for the sediment compartment. A list of uncertainties in relation to such approaches is given. SUMMARYSediment Environmental Risk Assessment (ERA) is a combination of exposure and effect assessment. Proposals for these assessments are provided. The opinion describes specific protection goals (SPGs) for sediment-inhabiting organisms based on two options (1) the ecological threshold option (ETO), accepting negligible population effects only, and (2) if applicable, the ecological recovery option (ERO), accepting some population-level effects if ecological recovery takes place within an acceptable time period.Triggers for sediment ecotoxicity testing are proposed together with a decision scheme for when additional testing may be required. The ecotoxicologically relevant concentrations (ERCs) for sediment organisms are proposed, as this will be influenced by the choice of sediment layer, exposure metric and test duration.The current Forum for the co-ordination of pesticide fate models and their use (FOCUS) methodology for surface water does not consider the effect of multi-year applications, which could possibly lead to accumulation of pesticides in sediment. To account for this deficit, a proposed methodology for introducing an accumulation factor that can be used until an updated FOCUS methodology becomes available is presented in this opinion. The accumulation factor can be considered a conservative approach, since it does not include any possible transport processes, such as leaching or volatilisation, which may reduce the accumulation in sediment in the real field situation.A tiered effect assessment approach is proposed for different sediment organisms and how to link regulatory acceptable concentrations (RACs) to predicted environmental concentration (PECs). The assessment of bioaccumulation, biomagnification and secondary poisoning is discussed, as well as the prospect of improving ERA for sediment microorganisms.Transformation products from active substances also may need to be assessed, as well as mixture toxicity of formulations of plant protection products (PPPs). The op...

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