On 17 August 2026, HSE formally adopted the 2023 EFSA guidance on risk assessment for birds and mammals (EFSA-Q-2017-00555) for Great Britain, replacing the 2009 version. This brings GB into line with the EU, where the same guidance came into force in October 2025 and applies directly in Northern Ireland.

 

What it means for applicants

From 17 February 2027, any GB application for active substance approval or plant protection product authorisation that relies on a new bird and mammal risk assessment must follow the 2023 guidance. Voluntary use is already permitted from 17 August 2026.

 

GB-specific clarifications to note

HSE has set out a handful of national clarifications to enable practical implementation:

  • Benchmark dose (BMD): NOAEL continues to be used until a BMD10 is agreed at active substance level.
  • Time weighted average (TWA): the 2009 TWA approach applies until the 2023 approach is agreed at active substance level.
  • Secondary poisoning and drinking water: benthic invertebrate and soil pore water exposure routes are not required until the supporting guidance is in place.
  • Higher tier / field studies: the Critical Appraisal Tool (CAT) approach is optional for GB submissions, reflecting the narrower range of conditions the assessment needs to cover.
  • Metabolites: ecotoxicologically relevant metabolites from the most recent active substance evaluation should be considered, regardless of whether that evaluation used 2009 or 2023 guidance.

Multi-active-substance mixture risk assessment guidance will follow in due course.

 

Navigating the transition?

CEA has deep expertise in bird and mammal risk assessment and has supported clients on BMD derivation, TWA refinements, higher-tier study design, and metabolite considerations across both GB and EU submissions. If you’re planning an upcoming application and want a second pair of eyes on your strategy or endpoints, get in touch at enquiries@cea-res.co.uk.

 

Full HSE summary and stakeholder response document available on Birds and mammals – risk assessment for ecotoxicology – HSE