EFSA’s updated Birds and Mammals Guidance: What it means for your pesticide risk assessment

Key Changes

Modelling approaches have been refined with more realistic exposure scenarios. The specificity of the worst-case crop groups has been increased resulting in 3 times more crop groups, and 17 times more scenarios for birds and 22 times more scenarios for mammals. Not to mention there is a new risk assessment for small mammals outside of the treated area but within the ‘Terrestrial Area of Interest’ (TAI). 

The database of residue unit doses (RUDs) underlying EFSA 2009 has also been re-evaluated and extended. The impacts of this change are evident in the screening assessment, with an increased likelihood of more substances requiring a Tier 1 risk assessment due to larger shortcut values (SV), the factor that describes the feeding habits and other ecological needs for the generic focal species. 

Another major update is the use of a 10% effect level (EL10) where appropriate, based on benchmark dose modelling (BMD) (using bayesian methodologies) rather than the no-observed-adverse-effect level (NOAEL) used previously. Depending on the setting of the test concentrations in relation to the effects observed, this change may cause an increasing or decreasing effect on the relevant endpoint to be used in the assessment. Recently, the Post Approval Issue (PAI) Group announced that until a BMD for the concerned active substance has been derived at EU level, the NOAEL should be used for all applications. 

The new guidance provides clearer rules for when the time-weighted average factor (fTWA) can be used to refine risk assessments for birds and mammals. There will be more cases where this will no longer be appropriate, causing higher risk outcomes than previous assessments. Once a member state has assessed whether this factor can or cannot be used for an active substance, this decision will apply to all EU member states. 

Several options for exposure refinement at Tier 2 and Tier 3 are available. At Tier 2, bespoke residue decline studies can be used to obtain substance-specific information on the dissipation and degradation of residues from plant material matrices relevant to intended product use. The DT50 values derived from such studies can also be used to refine the MAFacute value used for the acute assessment and/or the moving window MAFrepro × fTWA for the reproductive assessment. 

Tier 3 effects assessments may be triggered more frequently. However, the guidance has clearer criteria for interpretation of higher-tier studies such as field trials, mesocosm experiments and population modelling including increased clarity on design and conduct. Applicants will have a greater opportunity to robustly demonstrate realistic risk mitigation and reduce the conservatism from lower tiers. We can expect that dossiers will require careful planning and greater investment at Tier 3, but have better tools to ensure well-designed, regulatory acceptable studies are conducted for future-proofed risk assessments. 

Moreover, updates to the online EFSA birds and mammal’s calculator can lead to compatibility issues when uploading product data saved from earlier versions of the tool. Following the recent update to version 3.0.2, we observed that uploading previously saved product data triggered a warning that the uploaded file and data originated from an older version, potentially causing errors. As a result, the previously uploaded file and data became unusable. This complicates the process of reviewing previously completed data and risk assessments. Version control has been a recurring concern raised throughout the tool’s development and rollout.

How Enviresearch can help

Enviresearch ecotoxicologists have working experience with the new guidance document and are ready to help; from preliminary risk assessments and establishing the new endpoints through to working with you to create a full risk assessment strategy, design and monitoring of Tier 3 studies and everything in between. We can provide strategic advice on data requirements including data gap analyses and help with the identification of potential critical endpoints for available studies. This is particularly important in relation to the ecological relevance of primary effects in reproduction and development studies, and whether BMD modelling of available data is required and feasible. We can advise clients on the most suitable mathematical model for their data, the use of historical information to derive informative ‘priors’ for use with the Bayesian BMD model and can evaluate BMD analysis for its suitability for use in risk assessment. Additionally, we can provide pragmatic expert judgement on the ecological relevance of endpoints based upon primary effects on reproduction or development. In our experience, most endpoints are based on changes in growth, which allows the use of fTWA, while for other types of endpoints, it is expected that robust argumentation can be proposed to support the use of TWAs for most substances. 

Finally, where risks to birds and mammals cannot be excluded, we are well adept to support you with a higher tier strategy including higher tier studies and/or bespoke modelling (e.g. TKTD, refined exposure scenarios). 

Earlier in the year we conducted an internal workshop where each ecotoxicologist shared their working knowledge and experiences with the new guidance, to ensure we are ready to get to work! This was a huge success, spending the day together discussing all the new challenges, improvements and opportunities for birds and mammals risk assessments.