On September 2, 2025, the UK Health and Safety Executive (HSE) officially adopted Notice GB MRL2025/017, implementing a major revision to the Maximum Residue Limits (MRLs) for two pesticides: emamectin benzoate and thiabendazole. Centered on the core objective of "protecting human health" and aligned with the need for international trade compliance, this adjustment establishes a more rigorous food quality and safety framework by aligning with international standards and refining regulatory lists. The new MRL standards will take formal effect on March 2, 2026, with a six-month transition period allocated to the industrial chain for a smooth shift.​

Emamectin Benzoate: "Stringent Regulation" for Unapproved Substances​

As an active substance not approved for use in the UK, emamectin benzoate became a key target of this revision due to its potential health risks. In its preliminary notice issued on May 7, 2025, the HSE explicitly stated that residues of this substance in lettuce and milk might pose hazards to human health, thus initiating the process of lowering MRLs:​

Precise Tightening for Core Categories: The residue limit in lettuce plummeted from 1mg/kg to 0.01mg/kg, a reduction of 99%; for milk, the limit was further cut from 0.01mg/kg to 0.003mg/kg, fully aligning with the Codex Maximum Residue Limit (CXL) established by the Codex Alimentarius Commission (CAC). This standard, developed based on joint assessments by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), has been verified as non-hazardous to human health.​

Unified Standards Across Categories: For categories including Chinese cabbage and other leafy brassica vegetables (0.2mg/kg), spinach (0.05mg/kg), tea (0.1mg/kg), and edible offal (0.1mg/kg), the CAC’s CXL standards were directly adopted as statutory limits. Notably, the adjusted limit for tea is particularly significant—it represents a relaxation from the UK’s previous 0.02mg/kg standard (based on the limit of quantification), making it more compatible with actual production and trade needs.​

Trade-Oriented Supplementary List: To eliminate international trade barriers, new MRL standards were added for categories such as apricots, sweet cherries, peaches, three varieties of kiwifruit (green, red, and yellow), and infusions of dried leaves and herbs, achieving alignment with standards of major trading partners.​

Thiabendazole: "Safety Calibration" for Approved Substances​

As a widely used benzimidazole fungicide with protective, curative, and systemic properties, thiabendazole is commonly applied in the preservation of fruits and vegetables and the control of fungal diseases. Although approved for use in the UK, HSE risk assessments identified potential health risks from its residues in poultry eggs, prompting the optimization of standards:​

Significant Reduction in Poultry Egg Limits: The residue standard was lowered from 2mg/kg to 0.1mg/kg, strictly adhering to the CAC’s CXL. This adjustment scientifically aligns with thiabendazole’s Acceptable Daily Intake (ADI) of 0-0.1mg/kg body weight, controlling dietary intake risks at the source.​

Supplementation of Standards for Trade-Critical Categories: Exclusive MRLs were added for mangoes, sweet potatoes, and Belgian endives, addressing the longstanding challenge of lacking clear standards for these trade-relevant products. Such adjustments reflect the UK’s governance philosophy of "promoting trade through standards," consistent with the logic applied in the March 2025 revision of flupyradifurone limits.​

The Dual Logic Behind the Revision: Health Priority and Trade Synergy​

This MRL revision reflects distinct characteristics of the UK’s pesticide regulatory system post-Brexit. From a health protection perspective, the HSE has adopted a "risk-driven standard-setting" model, with scientific assessment as the core basis for MRL establishment—whether for the micro-residue control of emamectin benzoate in dairy products or the safety threshold calibration of thiabendazole in poultry eggs, all standards are anchored in the CAC’s internationally authoritative assessments, ensuring scientific rigor.​

From a trade adaptation perspective, the revision directly responds to market needs post-Brexit. Since its departure from the European Union, the UK has gradually developed an independent pesticide residue standard system; however, discrepancies between UK and EU standards risk triggering trade frictions. By fully adopting CAC standards, the revision not only provides clear production guidelines for domestic enterprises but also enhances the international market acceptance of UK exports—particularly supporting export-competitive categories such as tea, fruits, and vegetables.​

Industry Adaptation and Future Outlook​

To mitigate the impact of standard adjustments on the industrial chain, the HSE has set a six-month transition period, with the current standards remaining in effect until March 1, 2026. This arrangement provides food enterprises with a window to adjust processes, adapt testing protocols, and clear inventory. For export-oriented enterprises, two key changes require priority attention: first, the significant tightening of limits for core categories such as lettuce and poultry eggs, which necessitates the re-optimization of pesticide application protocols in planting and breeding; second, the need to quickly establish compliant quality control systems for categories with newly added MRLs.​

In the long term, this revision represents a crucial step in the UK’s development of an independent food quality system. As CAC standards gain increasing recognition in global trade (having been designated by the WTO as an international reference benchmark for food safety), the UK’s standard adjustments will not only elevate domestic food safety levels but also lay a solid foundation for its participation in global food trade. Going forward, relevant enterprises must continue to monitor HSE assessment updates to respond to potential standard revisions.