Scientific Opinion on safety and efficacy of cobalt carbonate as feed additive for ruminants, horses and rabbits

Cobalt(III) is a component of cobalamin. Its essentiality as trace element results from the capacity of certain animal species to synthesise cobalamin by the gastrointestinal microbiota. Feeding cobalt(II) carbonate up to the maximum authorised total cobalt in feed is safe for the target animals. Cobalt is predominantly excreted via the faecal route. Absorbed cobalt follows aqueous excretion routes. About 43 % of body cobalt is stored in muscle; however, kidney and liver are the edible tissues containing the highest cobalt concentrations and are most susceptible to reflect dietary cobalt concentrations. In animals with the capacity to synthesise cobalamin, cobalt is also deposited in tissues as vitamin B12. Cobalt(II) cations are genotoxic under in vitro and in vivo conditions. Cobalt(II) carbonate has carcinogen, mutagen and reproduction toxicant (CMR) properties. No data are available on the potential carcinogenicity of cobalt(II) following oral exposure. However, oral exposure may potentially entail adverse threshold-related effects in humans. The estimated population intake of cobalt most likely includes the contribution of foodstuffs from animals fed feedingstuffs that are routinely supplemented with cobalt(II) compounds. An increase in cobalt exposure by the use of cobalt-containing feed additives is therefore not to be expected. Considering the population exposure to cobalt, which is about 4–10 times lower than the health-based guidance value, no safety concern for the consumer is expected for threshold effects of oral cobalt. Cobalt(II) carbonate is a skin and eye irritant, and a dermal and respiratory sensitiser. Its dust is a hazard to persons handling the substance. Exposure by inhalation must be avoided. The use of cobalt from any source at the authorised maximum content in feed does not provide a risk to the environment. Cobalt(II) carbonate is available for cobalamin synthesis in the rumen and therefore effective in ruminants; this conclusion is extrapolated to horses and rabbits.