Opinion of the Scientific Panel on Additives and Products or Substances used in Animal Feed on a request from the European Commission on the evaluation of the coccidiostat COXIDIN® (Monensin Sodium)

Coxidin® (monensin sodium) is an additive intended for the control of coccidiosis, a debilitating protozoal infection in poultry, in feed for chickens for fattening and turkeys for fattening. Coxidin® contains as active agent 25% monensin sodium (Mo-Na), a polyether ionophore produced by Streptomyces cinnamonensis that exhibits both antibacterial and anticoccidial activities. The European Food Safety Authority, in accordance with Regulation (EC) No 1831/2003, has to assess the efficacy and the safety of this product for the target animals, the users, consumers and the environment. The applicant applies for dose levels from 100 to 125 mg Mo-Na kg-1 complete feedingstuff for chickens for fattening and from 60 to 100 mg Mo-Na kg-1 for turkeys for fattening. The efficacy of Mo-Na from Coxidin® was shown in chickens for fattening and turkeys for fattening in three floor pen studies and three field trials each. In chickens for fattening, 100 mg Mo-Na from Coxidin® kg-1 feed was shown as the lowest effective dose, and in turkeys for fattening, 90 mg Mo-Na from Coxidin® kg-1 feed. The lowest claimed dose for turkeys (60 mg Mo-Na from Coxidin® kg-1 feed) was not supported by data. No data on the development of Eimeria resistance against Coxidin® were submitted. However, no unusual resistance of Eimeria spp. to Mo-Na which eventually would invalidate the efficacy of monensin in chickens is to be expected in field. The limited data provided for Coxidin® and published results support that Mo-Na does not adversely affect the quality of chicken and turkey products. Tolerance tests showed that Coxidin® is safe for the target animals at the highest recommended level (125 mg kg-1 for chicken, 100 mg kg-1 for turkey). However, there was a small margin of safety (of less than twice the maximum recommended dose). The antimicrobial spectrum of monensin is mainly limited to aerobic and anaerobic Gram positive bacteria. Selection of resistant strains is not reported by antimicrobial resistance programmes. Monensin sodium can therefore be considered safe from a microbiological point of view for the target animal species. Incompatibilities or interactions with feedingstuffs, carriers, and other approved additives are not to be expected based on the known history of the additive. But there is a well known interaction with some medicinal substances (i.e. tiamulin) justifying a warning label on the product that the simultaneous use of these substances is contraindicated. Mo-Na at the use level for chickens and turkeys is poisonous to equines. In both the chicken and turkey Mo-Na is absorbed at a limited extent and excreted rapidly mainly through the faeces with a high proportion of unchanged monensin during the initial 8 hours investigated. From the limited data provided and the literature it can be concluded that the in the chicken, the turkey and the rat are similar. Submitted data on monensin residues in chicken and turkey show that the highest contents are found in the skin+fat then in the liver for both species, and that their remanence is very limited in all tissues (less than 24 hours) with the exception of the skin+fat (at least 5 days). The data available for chicken and turkey do not allow establishing the ratio of the proposed marker residue to total monensin related residues in tissues at different withdrawal times. As a consequence, the FEEDAP Panel is not in a position to evaluate the consumer's intake of total monensin residues and its compliance with the ADI. Therefore, no MRL (and withdrawal time) can be proposed for monensin from Coxidin® for chickens for fattening and turkeys for fattening. Mo-Na is not genotoxic in an adequate range of studies and has shown no structural alert for carcinogenesis. Mo-Na is not a reproductive or developmental toxin based on adequate current studies in rat and rabbit. The lowest NOEL identified in the developmental study in rabbits is 0.3 mg Mo-Na kg-1 bw day-1 for maternal toxicity. Applying a safety factor of 100 would result an ADI of 0.18 mg per 60 kg person. Mo-Na is highly toxic by inhalation; dermal exposure can significantly contribute to toxicity. Pure Mo-Na showed no irritant effects on the skin or the eye. Coxidin® 20% is not irritant to the skin but slightly irritant to the eye, and does not show a sensitisation potential by dermal exposure. Regarding the environmental risk assessment and based on the available data, it can not be excluded that the use of Coxidin® at the recommended dosage range will pose a risk for terrestrial and aquatic compartments.