Intermediate tier options in the environmental risk assessment of plant protection products for soil invertebrates - Synthesis of a workshop

The European environmental risk assessment (ERA) of plant protection products (PPPs) follows a tiered approach. The approach for soil invertebrates currently consists of two steps, starting with a Tier 1 assessment based on reproduction toxicity tests with earthworms, springtails, and predatory mites. In case an unacceptable risk is identified at Tier 1, field studies can be conducted as a higher tier option. For soil invertebrates, proposals for intermediate tiered studies are available from literature, however, they are not implemented in the risk assessment for various reasons. Hence, there is limited possibility to include additional information for the ERA to address specific concerns when the Tier 1 fails, as an alternative to e.g., a field study. Calibrated intermediate tier approaches could help to address risks for soil invertebrates with less time and resources but also with sufficient certainty. A multi-stakeholder workshop was held on 2nd to 4th of March 2022 to discuss potential intermediate tier options, focusing on four possible areas: 1) natural soil testing, 2) single species tests (other than standard species), 3) assessing recovery in laboratory tests, and 4) the use of assembled soil multi-species test systems. The participants acknowledged a large potential in the intermediate tier options but concluded that some issues need to be clarified before routine application of these approaches in the ERA is possible, i.e., sensitivity, reproducibility, reliability, and standardization of potential new test systems. The definition of suitable assessment factors needed to calibrate the approaches to the Protection Goals was acknowledged. The aims of the workshop were to foster scientific exchange and a data driven dialog, to discuss how the different approaches could be used in the risk assessment, and to identify research priorities for future work to address uncertainties and strengthen the tiered approach in the ERA of PPPs for soil invertebrates. This paper outlines the background, proposed methods, technical challenges, difficulties and opportunities in the ERA, and conclusions of the workshop.