Monensin sodium (Coxidin) renewed with the maximum dose lowered from 125 to 120 mg/kg: a new Daphnia magna reproduction study according to OECD 211 closed the aquatic risk assessment, EU-wide monitoring of Eimeria resistance from 2031
Commission Implementing Regulation (EU) 2026/532, published on 12 March 2026, renews until 1 April 2036 the authorisation of monensin sodium (Coxidin, Huvepharma N.V.) in the wheat bran and calcium carbonate formulations for chickens for fattening and reared for laying (100–120 mg/kg) and turkeys for fattening and reared for breeding up to 16 weeks (60–100 mg/kg). It repeals Regulations (EC) No 109/2007 and (EU) No 140/2012.
- The applicant lowered the maximum dose for chickens from 125 to 120 mg/kg, because in another tolerance study chicken growth already fell from 125 mg/kg. The new study (groups at 115, 120 and 125 mg/kg) showed no adverse effects, so in its opinion of 24 June 2025 EFSA considered 120 mg/kg safe, but did not set a margin of safety because the overdose was only 4 % higher.
- The aquatic risk was closed by a 21-day Daphnia magna reproduction study according to OECD 211 (semi-static design, 0.025–0.4 mg/L): EC10 = 0.17 mg/L. Measured concentrations were at times outside ±20 % of nominal, so geometric means were used. With a surface water PEC of 9.6 µg/L (FOCUS) and a PNEC of 17 µg/L the PEC/PNEC ratio is 0.56.
- For the calcium carbonate formulation in vitro studies were performed: OECD 439 (not a skin irritant), OECD 438 (eyes — “no prediction can be made”) and the LLNA in mice according to OECD 429 — skin sensitiser (GHS Category 1). Methods in the annex: HPLC-PCD-UV–Vis according to EN ISO 14183, in feed also LC-MS/MS according to EN 17299, in tissues HPLC-MS/MS.
- Maximum residue limits: 25 µg/kg skin with fat and 8 µg/kg liver, kidney and muscle. From 1 April 2031 the authorisation holder monitors Eimeria resistance across the EU (in vitro screening or sensitivity tests of strains from farms with signs of resistance), and from 1 April 2033 at the latest runs mixed-infection sensitivity tests in chickens and turkeys.