Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of cupric sulphate pentahydrate when used as feed additive for all animal species.
Copper sulphate pentahydrate is safe for all animal species/categories up to the maximum total copper content authorised in feed.
Consumption surveys include copper from foodstuffs of animal origin. Since the supplementation of animal feed with copper-containing compounds has not essentially changed over the last decade, no change in the contribution of foodstuffs originating from supplemented animals to the overall copper intake of consumers is expected. No concerns for consumer safety are expected from the use of copper sulphate pentahydrate in animal nutrition.
The maximum residue limits (MRLs) for copper in edible tissues and products of animal origin established by European Union pesticides legislation are found not to comply with the upper intake level set by the Scientific Committee on Food—as shown by different model calculations—and with legal feeding practices. The FEEDAP Panel is generally not in favour of establishing MRLs for essential nutrients, such as copper, in foods of animal origin, unless there is a clear consumer safety issue to do so; however, any such MRL has to consider animal health and welfare. In case MRLs for animal products are to be retained, the FEEDAP Panel proposes amended values.
Copper sulphate pentahydrate is an eye irritant but not a skin irritant or skin sensitiser; it may induce allergic dermatitis in sensitive persons, which might be exacerbated by the contamination with nickel. The dusting potential of the additive indicates that users may be exposed to hazardous copper concentrations by inhalation, which could result in a reduced immune response of the lung. The inhalation of nickel resulting from handling the additive is by itself unlikely to be of concern.
Potential risks to soil organisms have been identified as a result of the application of piglet manure. Levels of copper in other types of manure are too low to create a potential risk within the timescale considered. There might also be a potential environmental concern related to contamination of sediment owing to drainage and the run-off of copper to surface water. In order to draw a final conclusion, further model validation is needed and some further refinement to the assessment of copper-based feed additives in livestock needs to be considered, for which additional data would be required. The use of copper-containing additives in aquaculture up to the maximum authorised copper level in feeds is not expected to pose an appreciable risk to the environment.
The limited database available on the influence of copper on the development of antibiotic resistance in gut and soil bacteria allows to conclude that (i) high copper concentrations in the microbial environment increase the number of copper-resistant bacteria and (ii) copper resistance seems to be correlated with more frequent resistance to several antibiotics in certain bacterial species. A co-transfer of plasmid genes encoding for resistance to copper and erythromycin is plausible at least in Enterococcus faecium. The current database does not allow any conclusion on a potential threshold concentration of copper in feeds, below which a significant increase in copper resistance could not be expected. The total pool of macrolide resistance in animals probably originates from antibiotic treatment and not from the use of high dietary copper. The extent to which copper-resistant bacteria contribute to the overall antibiotic resistance situation can not be quantified at present. More precise (and quantitative) conclusions will require further studies.
The use of copper sulphate pentahydrate in animal nutrition is extensively documented in the scientific literature. It is recognised as an efficacious source of copper in meeting animal requirements.