Challenges in Soil Ecotoxicological Analytics
Challenges in Soil Ecotoxicological Analytics
On Thursday December 4th, 2025, Kerona Scientific held its 6th Virtual Dublin Plant Protection Symposium. Ricardo Petersen (ERM) presented an overview of the current challenges associated with soil ecotoxicological analytics, an area gaining increasing regulatory attention. His presentation provided a clear outline of the regulatory framework, analytical expectations, and implications for risk assessment.
Recent guidance from the Central Zone Working Document (2023) has introduced a stronger emphasis on analytical verification in soil studies. In particular, measured concentrations are required when the DT90 of an active substance is shorter than the duration of the study, both at the active substance and product level. This change could have significant practical implications. Ricardo presented estimates indicating that, for a representative group of active substances, compliance with the new analytical requirements may lead to the need for a substantial number of new soil studies, especially where degradation is rapid and historical studies lack measured exposure data.
A case study illustrated two contrasting outcomes. In one study, analytical verification aligned with nominal concentrations and the biological assessment proceeded as planned. In another, low initial recoveries for two fast-degrading substances prevented meaningful evaluation, resulting in the study being discontinued. This example highlighted the need for robust sampling strategies and consistent approaches to interpreting measured concentrations.
The presentation also outlined several technical questions that remain open, such as the number of sampling points required, how to address mixtures with active substances exhibiting different degradation rates, and how to interpret very low recoveries. These issues directly affect the calculation of PEC values, selection between PECmax and PECTWA, and ultimately the reliability of TER-based risk assessments.
In his conclusions, Ricardo emphasised the need for updated OECD guidance to harmonise analytical verification requirements, greater clarity on risk assessment approaches for fast-degrading substances, and alignment of regulatory expectations with practical and scientific constraints. As soil ecotoxicology continues to evolve, ensuring consistency and scientific robustness will be key to supporting both regulatory decision-making and environmental protection goals.
If you missed the Dublin Plant Protection Symposium, please contact Kerona if you wish to obtain a copy of the presentations. For assistance with the Regulation of PPP in the EU and UK the Kerona Regulatory team can be contacted at info@kerona.ie