Opinion of the Scientific Panel on additives and products or substances used in animal feed (FEEDAP) on the evaluation of the coccidiostat COXIDIN® (Monensin Sodium)

A multi-approach analysis of the toxicity of a commercial formulation of monensin on Rhinella arenarum embryos and larvae

Monensin, an antibacterial commonly used in animal fattening, can enter aquatic ecosystems and harm non-target organisms. Since there are no previous studies about the effects of monensin on amphibians, the aim of the present study was to evaluate the lethal and sublethal toxicity of a commercial formulation of monensin (CFM) through standardized bioassays with embryos and larvae of the amphibian Rhinella arenarum. Oxidative stress (catalase and glutathione S-transferase activities, and reduced glutathione and lipid peroxidation levels), cholinesterasic effect (acetylcholinesterase and butyrylcholinesterase activities) and mutagenicity (micronuclei frequency) biomarkers were evaluated. The CFM produced teratogenic effects, with a teratogenic index of 6.21. Embryos (504 h-LC50: 273.33 µg/L) were more sensitive than larvae, as no significant mortality was observed on larvae exposed up to 3000 µg/L for 504 h. However, oxidative stress, cholinesterasic effect and mutagenicity biomarkers were altered on larvae exposed for 96 h to environmentally relevant concentrations (4, 12 and 20 µg/L of monensin active ingredient). The CFM caused adverse effects on the exposed organisms, primarily on embryos, leading to lethal and sublethal effects, which could impact the wildlife when it reaches aquatic ecosystems.

Safety and efficacy of a feed additive consisting of monensin sodium (Coxidin®) for chickens for fattening, chickens reared for laying, turkeys for fattening and turkeys reared for breeding (Huvepharma N.V.)

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of monensin sodium (Coxidin®) as a coccidiostat for chickens for fattening, chickens reared for laying, turkeys for fattening and turkeys reared for breeding. The additive currently on the market complies with the existing conditions of authorisation. The FEEDAP Panel concluded that Coxidin® remains safe for turkeys for fattening (up to 16 weeks) and extends this conclusion to turkeys reared for breeding (up to 16 weeks). The Panel was not in the position to confirm that the current maximum authorised level of 125 mg monensin sodium/kg complete feed remains safe for chickens for fattening and chickens reared for laying. The use of monensin sodium from Coxidin® at the corresponding maximum authorised/proposed use levels in the target species is safe for the consumer. The existing maximum residue levels (MRLs) for poultry tissues ensure consumer safety. No withdrawal time is necessary. Both formulations of Coxidin® pose a risk by inhalation. The formulation with wheat bran as a carrier was neither irritant to the skin nor a skin sensitiser but it was irritant to the eyes. In the absence of data, no conclusions could be made on the potential of the formulation containing calcium carbonate to be irritant to skin and eyes and to be a skin sensitiser. The use of monensin sodium from Coxidin® in complete feed for the target species poses no risk for the terrestrial compartments and for sediment. No risk for groundwater is expected. For chickens for fattening the risk for aquatic compartment cannot be excluded, but no risks are expected for the other animal categories. There is no risk of secondary poisoning. Coxidin® is efficacious in controlling coccidiosis at a level of 100 mg/kg complete feed for chickens for fattening and at 60 mg/kg complete feed for turkeys for fattening. These conclusions are extended to chickens reared for laying and turkeys reared for breeding. The Panel noted that there are signs of development of resistance of Eimeria spp. to monensin sodium.

Co-exposure of Monensin Increased the Risks of Atrazine to Earthworms

Antibiotics could enter farmlands through sewage irrigation or manure application, causing combined pollution with pesticides. Antibiotics may affect the environmental fate of pesticides and even increase their bioavailability. In this study, the influence of monensin on the degradation, toxicity, and availability of atrazine in soil-earthworm microcosms was investigated. Monensin inhibited the degradation of atrazine, changed the metabolite patterns in soil, and increased the bioavailability of atrazine in earthworms. Atrazine and monensin had a significant synergistic effect on earthworms in the acute toxic test. In long-term toxicity tests, co-exposure of atrazine and monensin also led to worse effects on earthworms including oxidative stress, energy metabolism disruption, and cocoon production compared to single exposure. The expression of tight junction proteins was down-regulated significantly by monensin, indicating that the intestinal barrier of earthworms was weakened, possibly causing the increased bioavailability of atrazine. The expressions of heat shock protein 70 (Hsp70) and reproductive and ontogenetic factors (ANN, TCTP) were all downregulated in binary exposure, indicating that the resilience and cocoon production of earthworms were further weakened under combined pollution. Monensin disturbed the energy metabolism and weakened the intestinal barrier of earthworms. These results showed that monensin increased the risks of atrazine in agricultural areas.

Monensin occurrence in surface water and its impact on aquatic biota in a stream of the southeast Pampas, Argentina

Monensin is an ionophore antibiotic used as a feed additive and growth promoter in cattle production worldwide. The occurrence of monensin in aquatic surficial ecosystems is of concern due to its possible detrimental effects on human health and native biota. Argentina is one of the most important cattle beef producers worldwide; however, there is little knowledge on the environmental occurrence of monensin and the associated risks to aquatic biota. In this study, we developed a method for the extraction and quantification of monensin in surface water; then, we evaluated the occurrence of monensin in a stream impacted by different animal husbandry's operations, and then, we analyzed the ecological implications of monensin residues on aquatic organisms using the risk quotient (RQ) method. Sampling was carried out on August 2017 from the headwaters to the floodplain of the El Pantanoso stream, Buenos Aires province, Argentina. Monensin detection frequency was 75% (n = 20). The median level was 0.40 μg/L and the maximum concentration was 4.70 μg/L. The main input of monensin was from a cattle slaughterhouse, an activity that has not been considered before in the literature as a source of emission of veterinary pharmaceuticals into the environment. The RQ assessment showed that monensin levels could have potential negative effects on aquatic biota in the sampling site closest to the cattle slaughterhouse. The data obtained in this study shows that monensin was present in El Pantanoso surface waters at levels of high ecotoxicological risk to aquatic biota.

Safety and efficacy of Elancoban® G200 (monensin sodium) for chickens for fattening, chickens reared for laying and turkeys

The feed additive Elancoban® G200, containing the active substance monensin sodium, an ionophore anticoccidial, is intended to control coccidiosis in chickens for fattening, chickens reared for laying and turkeys. The FEEDAP Panel cannot conclude on the safety of the additive for the target species, consumer, user and environment with regard to the safety of the production strain. The following conclusions apply to monensin sodium included in the additive. Based on the available data set, the FEEDAP Panel cannot conclude on the safety of Elancoban® G200 for chickens for fattening. Monensin sodium is safe for turkeys for fattening with a margin of safety of 1.5. Monensin sodium is not genotoxic and not carcinogenic. The pharmacological no observed adverse effect level (NOAEL) of 0.345 mg monensin sodium/kg body weight (bw) per day was identified in dog. The acceptable daily intake (ADI) derived from this NOAEL is 0.003 mg monensin sodium/kg bw applying an uncertainty factor of 100. Elancoban® G200 is safe for the consumer. The existing maximum residue limits (MRLs) ensure consumer safety, provided that the withdrawal period of 1 day is respected. Elancoban® G200 is very irritant for the eye, but it is not a skin irritant. Elancoban® G200 should be regarded as a potential skin and respiratory sensitiser. Inhalation exposure is considered a risk to persons handling the additive. Elancoban® G200 does not pose a risk for the terrestrial compartment, the aquatic compartment and the sediment. The bioaccumulation potential of monensin in the environment is low. Monensin sodium from Elancoban® G200 has the potential to effectively control coccidiosis in chickens for fattening and chickens reared for laying. The FEEDAP Panel cannot conclude on the efficacy Elancoban® G200 as a coccidiostat for turkeys for fattening.

Safety and efficacy of Monimax® (monensin sodium and nicarbazin) for chickens for fattening and chickens reared for laying

The coccidiostat Monimax® (monensin sodium and nicarbazin) is considered safe for chickens for fattening and chickens reared for laying at the highest use level of 50 mg monensin and 50 mg nicarbazin/kg complete feed. This conclusion is extended to chickens reared for laying. For both active substances, the metabolic pathways in the chicken are similar to those in the turkey and rat. Nicarbazin, when ingested, is rapidly split in its two components dinitrocarbanilide (DNC) and 2-hydroxy-4,6-dimethylpyrimidine (HDP) which behave independently. Monimax® does not represent a genotoxic risk. No safety concerns would arise from the nicarbazin impurities p-nitroaniline and methyl(4-nitrophenyl) carbamate. The lowest no observed effect level (NOEL) identified for monensin sodium in a developmental study in rabbits is 0.3 mg monensin sodium/kg body weight (bw) per day for maternal toxicity in rabbits. The lowest no observed adverse effect level (NOAEL) identified in a 52-week study in rat using DNC + HDP was 20 mg DNC + 8 mg HDP/kg bw per day based on the absence of microcrystals in urine and related microscopic renal observations. No significant interaction between monensin sodium and nicarbazin is expected from toxicological studies. The use of Monimax® at the highest proposed dose will not pose a risk to persons consuming animal products from treated chickens for fattening. This conclusion is extended to chickens reared for laying. No withdrawal time is required for Monimax® in chickens for fattening. Residue data comply with the established maximum residue limits (MRLs) for monensin and DNC. Based on the available data, the FEEDAP Panel cannot conclude on the safety of Monimax® for the environment. Monimax® has the potential to control coccidiosis in chickens for fattening at a minimum concentration of 40 mg monensin and 40 mg nicarbazin/kg complete feed.

Safety and efficacy of Monteban® G100 (narasin) for chickens for fattening

The feed additive Monteban® G100, containing the active substance narasin, an ionophore anticoccidial, is intended to control coccidiosis in chickens for fattening at a dose of 60-70 mg/kg complete feed. Narasin is produced by fermentation. Limited data on the taxonomic identification of the production strain did not allow the proper identification of strain NRRL 8092 as Streptomyces aureofaciens. The FEEDAP Panel cannot conclude on the absence of genetic determinants for antimicrobial resistance in Streptomyces spp. under assessment. Based on the available data set, the FEEDAP Panel cannot conclude on the safety of Monteban® G100 for chickens for fattening. The simultaneous use of Monteban® G100 and certain antibiotic drugs (e.g. tiamulin) is contraindicated. Narasin is not genotoxic. No indication of carcinogenicity or developmental toxicity was found at the doses tested in the mouse, rat and rabbit. The lowest no observed effect level (NOEL) identified in the oral toxicity studies was 0.5 mg/kg body weight (bw) per day for the neuropathy seen in a one-year dog study. The acceptable daily intake (ADI) derived from this NOEL is 0.005 mg narasin/kg bw applying a uncertainty factor of 100. Monteban® G100 is safe for the consumer. Maximum residue limits (MRLs) of 50 μg narasin/kg for all wet tissues ensure consumer safety. Monteban® G100 is irritatant to the eyes but not to the skin. It has the potential to induce skin sensitisation. Inhalation exposure would pose a risk to persons handling the additive. Narasin, when used as a feed additive for chickens for fattening at 70 mg/kg feed, is not expected to pose a risk to the environment. The risk for sediment compartment cannot be assessed. The FEEDAP Panel cannot conclude on the efficacy of Monteban® at the minimum applied dose of 60 mg narasin/kg complete feed for chickens for fattening.

Safety and efficacy of Monimax® (monensin sodium and nicarbazin) for turkeys for fattening

The coccidiostat Monimax^® (monensin sodium and nicarbazin) is considered safe for turkeys for fattening at the highest use level of 50 mg monensin and 50 mg nicarbazin/kg complete feed. The simultaneous use of Monimax^® and certain antibiotic drugs (i.e. tiamulin) is contraindicated. For both active substances, the metabolic pathways in the chicken are similar to those in the turkey and rat. Nicarbazin, when ingested, is rapidly split in its two components dinitrocarbanilide (DNC) and 2‐hydroxy‐4,6‐dimethylpyrimidine (HDP) which behave independently. Monimax^® does not represent a genotoxic risk. No safety concerns would arise from the nicarbazin impurities p‐nitroaniline and methyl(4‐nitrophenyl) carbamate. The lowest no observed effect level (NOEL) identified for monensin sodium in a developmental study in rabbits was 0.3 mg monensin sodium/kg body weight (bw) per day for maternal toxicity in rabbits. The lowest no observed adverse effect level (NOAEL) identified in a 52‐week study in rat using DNC + HDP was 20 mg DNC + 8 mg HDP/kg bw per day. No significant interaction between monensin sodium and nicarbazin is expected from toxicological studies. The use of Monimax^® at the highest proposed dose will not pose a risk to persons consuming animal products from treated turkeys for fattening. No withdrawal time is required for Monimax^® in turkeys for fattening. Residue data comply with the established maximum residue limits for monensin and DNC. Monensin sodium presents a hazard by inhalation and may also be associated with dermal toxicity. Monimax^® is not a skin irritant; however, no data are available for the eye irritation potential of monensin. Monimax^® is not a skin sensitiser. Based on the available data, the FEEDAP Panel cannot conclude on the safety of Monimax^® for the environment. Monimax^® has the potential to control coccidiosis in turkeys for fattening at a minimum concentration of 40 mg monensin and 40 mg nicarbazin/kg complete feed.

Safety and efficacy of Avatec® 150G (lasalocid A sodium) for chickens for fattening and chickens reared for laying, and modification of the terms of authorisation for chickens for fattening, chickens reared for laying, turkeys for fattening, minor avian species (pheasants, guinea fowl, quails and partridges) except laying birds

Avatec^® 150G is an anticoccidial feed additive containing 15% of the active ingredient lasalocid A sodium, an ionophore anticoccidial. The tolerance study indicated that oral administration of lasalocid A sodium via feed at doses at and above the targeted lasalocid dose of 125 mg/kg was not tolerated in chickens for fattening. Consequently, no safe dose can be established by the tolerance study submitted. Concurrent administration of lasalocid with tiamulin and certain other medicinal substances should be avoided. Lasalocid sodium has a selective antimicrobial activity against Gram‐positive bacterial species while many Enterobacteriaceae are naturally resistant. Induction of resistance and/or cross‐resistance was not observed in experimental conditions. Lasalocid A sodium is not genotoxic and not carcinogenic. The newly conducted cardiovascular study in dogs indicated an acute no‐observed‐adverse‐effect level (NOAEL) of 1 mg/kg body weight (bw) per day. Since this NOAEL is above the lowest NOAEL of 0.5 mg/kg bw per day previously identified in a 2‐year toxicity study in rats and a developmental study in rabbits, it is concluded that this NOAEL (0.5 mg/kg bw per day) is an appropriate base for establishing an Acceptable Daily Intake of 0.005 mg lasalocid sodium/kg bw. The use of lasalocid A sodium from Avatec^® 150G at the highest proposed level of 125 mg/kg complete feed is safe for the consumer. For compliance with the maximum residue limits (MRLs), a withdrawal period of 3 days is necessary. No risk for the user is expected from the use of Avatec^® 150G. The use of lasalocid A sodium from Avatec^® 150G in feed for chickens for fattening and chickens reared for laying up to the highest proposed dose does not pose a risk for the environment. Insufficient evidence of the anticoccidial efficacy of lasalocid A sodium was provided in chickens for fattening/reared for laying.

Long-term broiler litter amendments can alter the soil's capacity to sorb monensin

Monensin is a common antiparasitic drug given to poultry that contaminates poultry manure and bedding material (broiler litter). As broiler litter is commonly applied to agricultural fields as fertilizer, monensin could be released beyond the farm if it is not retained or degraded in the soil. This study aimed to assess the impact of long-term surface application of broiler litter (i.e., 17 years) on the capacity of pasture soil to sorb monensin. The soils were exposed to a range of monensin concentrations (0.18 to 1.81 μmol L^-1), solution pH (pH 4-9), and temperatures (15, 25, and 35 °C) and monensin was measured as loss from solution (i.e., sorption). Soils receiving long-term litter applications were hypothesized to retain more monensin than unamended soils because they have higher organic matter concentrations. However, soils from broiler litter-amended fields sorbed 46% less monensin than soils from unamended fields, likely because broiler litter also increased soil pH. The sorption of monensin to soil was strongly influenced by pH, with an order of magnitude greater sorption at pH 4 than at pH 9. Both soils had similar capacity to sorb monensin under similar solution pH, despite differences in organic carbon content (with the broiler litter-amended having 25% greater relative to the unamended soil). Temperature did not significantly impact monensin sorption for either soil. Our findings suggest increasing soil pH, for instance through liming, could enhance mobility of monensin.