EFSA releases scientific opinion on cobalt use in animal feed

 

 

The European Food Safety Authority (EFSA) has released a paper on the use of cobalt compounds in animal feed, in consideration of human health.

 

Cobalt dichloride and cobalt sulfate are of low acute toxicity but are classified as respiratory and skin sensitizers, as acute and chronic toxicants to the aquatic environment and as presumed human carcinogens by the inhalatory route. Cobalt(II) cations are also considered genotoxic under in vitro and in vivo conditions.

 

In light of the above properties of cobalt and since several cobalt compounds are authorised by EU legislation as feed additives, a risk assessment of the use of cobalt compounds in animal nutrition was undertaken considering,

• the necessity of cobalt supplementation for the target species including potential adverse effects of minimising/withdrawing cobalt supplementation on animal health 
   
• the safety for consumers of foods from animals treated with cobalt salts, and
   
• the safety of persons handling cobalt compounds as feed additives.

Monogastric animals (excluding horses and rabbits) do not require cobalt but they require vitamin B12. Consequently, there is no need for any cobalt supplementation to their feed.

 

The ruminal microflora can synthesize vitamin B12, provided dietary cobalt is available in sufficient quantities. Consequently, the vitamin B12 requirement of these animals can be covered by dietary cobalt. The organism of ruminants also requires only vitamin B12.

 

But for a potential replacement of cobalt by vitamin B12, there are not enough data to evaluate the consequences on health and performance for these species under field conditions. Such a replacement is also considered inefficient because of the high ruminal degradation rate of oral vitamin B12. A withdrawal of cobalt supplementation from the diet would also affect ruminal microbiota, its composition and function.

 

Some small beneficial effects observed in ruminants after cobalt supply are likely to be related to an unspecific cobalt effect on the microbiota rather than to vitamin B12. An optimal micronutrient supply of ruminants would therefore include cobalt.

 

The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the potential cobalt supplementation to diets for ruminants, horses and rabbits should be maintained.

 

A cobalt supplementation of 0.3 mg/kg dry matter and, taking into account cobalt background concentrations of feed material not exceeding 0.5 mg/kg dry matter of complete feed, a maximum content of 1mg Co/kg complete feed, is considered appropriate.

 

For fish diets, the existing maximum content of 2mg Co/kg complete feed should be maintained due to the higher background levels of Co in fishmeal, a major part of fish diets.

 

The tolerance of ruminants to cobalt is very high and greatly in excess of the requirements. Therefore, it is considered unlikely that cobalt toxicity in target animals could be a major problem in practice.

 

Among foodstuffs of animal origin, offal shows the highest cobalt content, liver with about 0.02-0.07 mg/kg fresh weight (FW), followed by kidney with about 0.001-0.01 mg/kg FW. Meat is in the range of 0.001-0.02 mg/kg FW as are fillets of freshwater fish. Milk and eggs contain about 0.004-0.005 mg Co/kg; dairy products like cheese and butter are relatively rich in cobalt (0.02 mg/kg FW).

 

Virtually all cobalt in offal and beef meat can be attributed to vitamin B12. The fraction of vitamin B12-bound cobalt is considerably smaller in poultry and pork meat indicating dietary supply of cobalt as such. Eggs and milk contain even higher amounts of vitamin B12 unrelated cobalt indicating excretion of absorbed soluble cobalt.

 

However, these are estimates with several uncertainties due to methodological reasons such as poor data set, analytical methods.

 

The exposure to cobalt via the oral route may potentially entail a number of adverse health effects in humans.

 

A daily oral intake of 600 μg Co appears a minimum risk level for humans that would protect from the known threshold-related adverse effects.

 

The FEEDAP Panel concluded that the potential cobalt intake of consumers from food of animal origin would not exceed 14 μg/day and is therefore not of safety concern.

 

The FEEDAP Panel also recommends modifying the authorisation of cobalt compounds in feedstuffs by,

• restricting the use of cobalt compounds as additives to feed for ruminants (except milk replacer), horses and rabbits, 
   
• limiting cobalt supplementation in feed for ruminants (except milk replacer), horses and rabbits to a maximum of 0.3 mg Co/kg complete feed, and
   
• reducing the authorised maximum cobalt content from all sources from 2 to 1mg/kg complete feed for all species except fish.

No negative consequences of these measures on animal health and the efficiency of animal production are expected.