Intermediate-tier options in the environmental risk assessment of plant protection products for soil invertebrates—Synthesis of a workshop
Authors: Ernst Gregor , Amorim Mónica J. B. , Bottoms Melanie , Brooks Amy C. , Hodson Mark E. , Kimmel Stefan , Kotschik Pia , Marx Michael T. , Natal-da-Luz Tiago , Pelosi Céline , Pieper Silvia , Schimera Agnes , Scott-Fordsmand Janeck , Sharples Amanda , Sousa José P. , van Gestel Cornelis A. M. , van Hall Bart , Bergtold Matthias 
Published: August 2023

Abstract
The European environmental risk assessment (ERA) of plant protection products 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, intermediate tiers are not implemented. 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, for example, 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 multistakeholder workshop was held on 2–4 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 multispecies 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, that is, 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 for soil invertebrates. This article outlines the background, proposed methods, technical challenges, difficulties and opportunities in the ERA, and conclusions of the workshop. Integr Environ Assess Manag 2024;20:780–793. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
Abstract
The introduction of intermediate tiers in the environmental risk assessment of plant protection products for soil organisms can help to reduce uncertainties in the risk assessment and serve as a bridge between the Tier 1 and higher-tier risk assessment. Proposals for intermediate-tier effect studies are available; however, further research on standardization and reproducibility is necessary before their implementation in test guidelines and risk assessment guidance documents. More work on calibration of intermediate tiers is necessary, that is, the generation of case studies that can help to better understand the relationship between the outcome of the different test options and the specific and general protection goals.