Regulatory Tools and Guidance in Focus at ERAR 2025 

As in previous years the presentations on regulatory issues ranged from experience of newly implemented guidance and guidance soon to be implemented, guidance under development and strategic research on potential future considerations such as effects of unintentional mixtures present in the wider environment. 

Common themes in presentations on newly and soon-to-be implemented guidance were that the guidance documents themselves lacked clarity and the complex calculator tools issued by EFSA were variously difficult to use. The CropLife Europe Bee sub-group reported that B-risk v1.0.0, the R-based calculator tool released in November 2024 and designed for use with the EFSA 2023 revised bee guidance, contains multiple bugs and critical errors, but to date no updates have been released or are scheduled for release. In contrast to the Excel spreadsheets and their embedded simple calculations that use agreed endpoints for lower-tier risk assessments, the new R-based tool is complex and will recalculate dose responses for user-entered raw toxicity data for every risk assessment. Consequently, at the present time there is uncertainty as to the reproducibility of risk assessments. 

Comparable issues were identified by Edna Rödig and colleagues at Syngenta concerning the 2022 guidance on soil phototransformation products in groundwater, and the soil photolysis modules in FOCUS PEARL and PELMO. As users will know, the FOCUS GW models were developed to predict worst-case leaching at a 1 m depth using parameterised and calibrated scenarios, and both models have been cross-validated. The same cannot be said for the photolysis modules in the FOCUS GW models, which have not been explicitly developed to predict environmental processes in the surface layer (1-2 mm). The substance distribution to soil column routines differ in both models leading to significant differences in exposure to photolysis, presumably leading to significant differences in PECGW values. Thus, activities to align model assumptions, followed by appropriate updates to the associated guidance are recommended. Progress on just these activities for the aged sorption guidance document was reported by Ian Hardy, representing the working group to which Wendy van Beinum contributes. Revision 2 of the guidance document is being drafted, templates and instructions to aid the use and evaluation of the P5-metric Excel spreadsheet tool are being developed, as are instructions for PEARL/PEST inverse-optimisation for field DegT50EQ. 

The release of genuinely improved tools and guidance on their use was announced by HSE CRD. For Tier I assesments, DFOP parent kinetics and functionality for parent and metabolite calculations have been added to an expanded PECsoil calculator tool. Similarly, the separate tools for spray drift and Tier I drainflow calculations have been combined into a single tool. With less ‘a-do’ than might be expected for something that has been ‘coming soon’ for a long time, the new version of the Higher Tier Drainflow Tool (v2.2) has now been published. In this version, minor bugs have been corrected and grassland is now included as a standard crop option. It is accompanied by two processing tools, that integrate information from higher tier drainflow runs and updated crop/soil/climate specific spatial data, specifically to support risk assessment in accordance with Approach 2, i.e. ‘SEISMIC’ has been replaced. New guidance on how to compare exposure in higher tier studies (mesocosms) with the output from higher tier drainflow modelling is also now available. 

At a far earlier stage, was the work presented by Charles Hazlerigg from the SETAC workshops on the use of Models for Assessing PoPulation relevance of Endocrine Disrupting effects (MAPPED). According to ECHA & EFSA (2018), the population relevance of endocrine disrupting chemicals can be investigated in different ways: field studies, monitoring data, and population modelling. Whilst, modelling does not suffer from the practical limitations inherent with field and monitoring studies (such as questions regarding the representativeness of a certain field site across various scenarios or the need to consider long durations that are necessary to identify population-level responses), it does have its own challenges (such as suitable scenario development and choice of model species). Furthermore, with a focus on the aquatic arena, whilst there is considerable literature on fish models, amphibians and the T-modality are less well representated in the modelling literature at the current time with life histories that occupy a range of habitats according to developmental stage and migrate between multiple habitats during the year adding to their complexity. This work is still ongoing with outputs expected in the new year… 

There was lots to digest from the excellent presentations as always, whilst the opportunity to catch up with others active in the UK chemical safety scene was second to none. It was great to see our fellow scientists and thanks to Syngenta for the filling lunch and cakes. We look forward to doing it all again next year.