On September 8, 2025, the European Food Safety Authority (EFSA) officially published its peer review report on the pesticide risk assessment of the active substance pinoxaden, offering a detailed risk profile for this widely used herbicide in European agricultural fields. Pinoxaden, commonly known by its trade name "Axial," effectively controls graminaceous weeds in winter and spring cereal crops by inhibiting acetyl-CoA carboxylase (ACCase). When the substance was approved in the EU in 2016, a crucial precondition was attached: given its subsequent formal classification as reproductive toxicant category 2 (H361d, suspected of damaging the unborn child), the applicant, Syngenta, was required to submit relevant risk assessment data for its specific metabolites M11, M52, M54, M55, and M56. With this toxicity classification officially adopted at the EU level, the confirmatory data assessment procedure, coordinated by Austria as the rapporteur Member State and led by EFSA, was initiated to fill the previously identified scientific gaps.

The core of this in-depth assessment rested on two critical scientific pillars. Firstly, it utilized real-world monitoring data collected from 70 carefully selected highly vulnerable groundwater monitoring points across five European countries—France, Germany, Italy, Lithuania, and the United Kingdom—spanning the period from 2015 to 2020. This extensive empirical data provided more realistic and reliable exposure scenarios, significantly enhancing the scientific rigor of the assessment compared to purely theoretical model predictions. Secondly, EFSA strictly adhered to the official EU guidance (SANCO/221/2000), implementing a tiered toxicological "relevance" assessment framework for seven key metabolites. This framework subjected the metabolites to a step-by-step screening, covering biological activity, genotoxicity, and general toxicity, with the aim of determining whether they were "relevant" to the specific toxicity concerns for which the parent substance pinoxaden was classified, thereby providing precise information for risk management.

The assessment results shed light on the current state of groundwater exposure: after normalizing actual application doses to representative use levels, at least one metabolite concentration exceeded the legal limit of 0.1 µg/L in 5 of the 70 monitoring points, representing approximately 7% of the total. These exceedances were not isolated but occurred in regions representing different climatic zones, specifically Thiva (4/21) and Hamburg (1/33), indicating potential risks under specific geographical and hydrological conditions. However, the report also emphasized that the assessment did not reveal systemic or widespread exceedances, suggesting that current exposure levels do not yet constitute a "critical area of concern" necessitating immediate EU-wide bans.

In the detailed risk classification of metabolites, EFSA presented clear and differentiated conclusions. Metabolite M3 was explicitly deemed "not relevant," a conclusion based on robust toxicological evidence: it showed no genotoxicity, and the observed effects of skeletal development delay in rabbit developmental toxicity studies were not severe enough to warrant classification. Furthermore, a combined dietary (via the food chain) and drinking water exposure assessment indicated that the maximum chronic exposure for all population groups (including the most sensitive infants) represented only 2.6% of its established Acceptable Daily Intake (ADI) for M3, implying negligible risk. Conversely, the other six metabolites—M2, M11, M52, M54, M55, and M56—were classified as "relevant." This classification was primarily based on the "lack of sufficient data to demonstrate that these metabolites do not share the reproductive toxic properties for which the parent substance pinoxaden was classified as H361d." Notably, metabolite M55 received additional scrutiny due to indications of potential genotoxicity. The EFSA expert panel, during the review process, explicitly rejected the applicant's proposal to extrapolate M3 data for the assessment of other metabolites, deeming such an extrapolation to lack sufficient scientific justification.

The scientific conclusions issued by EFSA in this report have profound implications and impacts for the future of the EU's pesticide regulatory framework. Firstly, it signals a trend towards decentralization of risk management responsibilities: subsequent risk management efforts will increasingly fall to the Member States. National authorities, when authorizing product use in the future, will need to more thoroughly consider local hydrogeological and climatic conditions, potentially implementing stricter restrictions in identified highly vulnerable areas (such as the Thiva climatic zone), including further reductions in application rates, adjustments to application timing, or the establishment of wider buffer zones. Secondly, this case established the authoritative and indispensable role of large-scale, targeted groundwater monitoring in high-level risk assessments. This indicates that future EU pesticide risk management will rely more heavily on such detailed empirical data, rather than solely on model predictions. Finally, this assessment not only fulfilled the legal obligation set at the time of the 2016 approval, successfully resolving the scientific uncertainties that existed then, but also laid a solid foundation for future ongoing monitoring and data review, especially for those metabolites identified as "relevant," which will require continuous attention and evaluation.