UK Lowers Methidathion Maximum Residue Levels

Background on Methidathion Regulation

Methidathion, an organophosphate pesticide previously used in various agricultural applications, faced regulatory changes after being linked to health concerns. The pesticide was banned in the EU in 2004 and subsequently in Great Britain after Brexit. The Codex Alimentarius Commission formally revoked all methidathion Codex MRLs in December 2023, following the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) findings, which indicated significant health risks.

HSE Review and MRL Adjustment

In line with the UK's commitment to food safety, the HSE conducted an extensive review of methidathion residues in food. The review, performed under Article 12 of GB’s pesticide regulations, involved evaluating updated toxicological data, including the Acceptable Daily Intake (ADI) and Acute Reference Dose (ARfD), both revised by JMPR in 2022. With these benchmarks in place, HSE determined that any presence of methidathion above the limit of quantification (LOQ) posed a potential health risk, leading to the proposal of the lowest feasible MRL for all methidathion residues in food products​​.

New Residue Limits and International Compliance

The newly adopted MRLs set methidathion at an LOQ of 0.01 mg/kg for most food categories, with certain challenging matrices, like herbs, assigned a higher default limit. These updated limits comply with international Codex standards, ensuring consistency in food trade and safety standards globally. Notably, the new limits will come into effect on 5 May 2025, allowing food business operators time to comply with these updated regulations.

Consumer Health and Future Implications

The tightened methidathion MRLs underscore the UK's commitment to maintaining high food safety standards. The decision to lower methidathion MRLs to near-zero levels reflects the government’s precautionary stance on pesticides linked to acute and chronic toxicity risks. With methidathion now absent from authorised plant protection products in Great Britain, these stringent MRLs are expected to safeguard consumer health and enhance confidence in domestic and imported food products​.