EFSA birds and mammals guidance 2023: how to prepare for risk assessment changes

The enforcement date for the revised European Food Safety Authority (EFSA) guidance on risk assessment for birds and mammals is not yet known. However, it’s advisable to establish the impact on pesticide active substances and products sooner rather than later. We’ve conducted several compound reviews aligned with the new guidance and can attest that there will be significant ramifications for the PPP sector.

All PPPs undergo risk assessment prior to placement on the EU market and at their periodic renewal of authorisation, in accordance with Regulation (EC) No 1107/2009. The tiered system becomes progressively more complex and specific in its requirements for PPPs which hold greater potential for ecotoxicological risk.

Substance reviews we’ve performed in readiness for EFSA (2023) guidance indicate that many changes will make it harder for PPPs to pass the Tier 1 assessment.

Our advice is to be proactive, conducting a systematic review of active substances and products across the portfolio. The first step would be to identify which PPPs require renewal of authorisation first. Once this has been established, those containing active substances already close to the margin of failure based on EFSA (2009) guidance should be prioritised for compound analysis aligned with the new requirements. It’s important to work ahead to allow enough time to conduct preliminary assessments, and further studies to support higher tier risk assessments should they be needed.

The new guidance involves a significant number of changes. These include (but are not limited to) indicator model species, generic model species, residues per unit dose, deposition factors, introduction of benthic invertebrate-eating species, consideration of exposure outside of the treated area but in the terrestrial area of interest.

Based on our evaluation of the new guidance, two connected and critical areas are: restricted use of the time weighted average factor (fTWA) and changes to the toxicity endpoints used in long-term assessments.

Under the previous guidance, a default fTWA of 0.53 could be applied when determining the long-term exposure to an active substance. This equates to an estimation of the 21-day TWA concentration in the diet assuming a default half-life (the time taken to reduce by half as environmental dissipation occurs) of ten days. EFSA (2023) does not allow this default option, instead requiring an assessment to determine whether it is appropriate to use an fTWA in conjunction with the lowest ecologically relevant endpoint based on available toxicity data.

The initial focus of the fTWA change is the mammalian dataset, because if the fTWA is not allowable for mammals, it is also precluded for birds. Further, EFSA (2023) guidance explicitly states that fTWA 0.53 cannot be used in avian long-term risk assessments where the LD₅₀/10 endpoint applies, which is already a conservative approach. One of our colleagues takes a more detailed look at the implications of this here.

Another new requirement that may result in more conservative Tier 1 assessments is the introduction of standard benchmark dose modelling (BMD), set at the 10 percent level (BMD10). BMD is considered a more appropriate method than the no-observed-adverse-effect-level (NOAEL) approach previously used, as it makes use of the whole dataset across the dose levels used in the study instead of just one treatment group. Separate EFSA guidance on BMD was published in 2022.

Before calculating BMD10 for reproductive risk assessments, the ecological relevance of effects should be considered. EFSA (2023) provides more detailed guidance on this matter making it easier to determine factors that the authority would deem ecologically relevant. Where relevant, the dose responses observed also need to be considered to indicate whether BMD calculations would be possible. For PPPs already on market, it’s a good idea to get ahead, performing risk assessment calculations using BMD10 (where relevant and possible) to reveal the impact of changes to toxicity endpoints.

Together, the developments surrounding fTWA and BMD will result in fewer compounds passing Tier 1 assessments under the new EFSA guidance.

Understanding which compounds are likely to fail Tier 1 risk assessments is vital to inform and shape regulatory strategy. Higher tier assessments may require more specific data that is representative of real species and environments. Since new studies may be needed to generate this data, early planning and preparation is essential, especially where field trials subject to seasonal variations are necessary.

Online tools have been developed by EFSA to support the transition to the new guidance. A beta version of the birds and mammals risk assessment calculator is available here, along with detailed guidance on its use. There are also two BMD EFSA Tools available, the Frequentist and Bayesian models, with the Bayesian method being recommended in the guidance to make full use of prior probabilistic distribution data. Careful consideration is required to determine which is the most appropriate for the dataset in question.

Here at TSG we offer preliminary assessments to ascertain the impact of the new guidance on individual active substances, products or entire product portfolios. We also conduct more detailed compound analysis when required, and can advise on next steps if additional data is likely to be needed. If you’re looking for expert support and scientific insights on how to respond to EFSA (2023) birds and mammals guidance, please get in touch.