Analyses of residues of therapeutic agents, illegal substances and pollutants in farmed fish

In order to document food safety, NIFES has analysed the content of illegal and legal pharmaceuticals and other undesirable substances in samples of Norwegian farmed fish sampled in 2008.

On behalf of the Norwegian Food Safety Authority, the National Institute of Nutrition and Seafood Research (NIFES) has analysed individual and pooled samples of farmed fish representing a total of 9066 fish (salmon, rainbow trout, turbot, halibut, cod, Arctic charr and saithe). These were analysed for illegal and legal therapeutic agents, and other undesirables. Samples were taken from all parts of the country throughout 2008, representing about 10% of the fish farms in Norway.

Illegal therapeutic agents
Samples of fish were collected at different stages in the production cycle. There were no findings of residues of illegal therapeutic agents, including hormone-like substances (growth promoters), in any of the samples analysed.

Legally used veterinary therapeutic agents and pollutants (undesirable substances)
Samples of farmed fish were taken at the processing plant and then analysed.

- Analyses were made to determine the content of undesirables, such as DDT, PCB7, hexachlorocyclohexane, hexachlorbenzene, heptachlor, aldrin, chlordan, nonachlor, endosulphane and toxaphene, dioxins, furanes and dioxin-like PCBs, as well as bromated frame retardants, PAH and PFOS. The level of the metals arsenic, cadmium, mercury and lead was also measured. The EU's upper limit was not exceeded for any of the samples where a limit has been set. Also the levels were generally low.

- Some pooled samples of fish were analysed for emamectin benzoate. Emamectin benzoate is utilized in sealouse treatments, and is added to the fish feed. Residues of emamectin benzoate were detected in samples of farmed salmon, but the levels were low, the highest being 9.1 microgram/kilo wet weight. The EU has set a Maximum Residue Limits (MRL) for emamectin benzoate at 100 microgram/kilo wet weight.

- Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and ethoxyquine (EQ) are synthetic antioxidants which are permitted for use in fish feed. It is important to examine its use in fish feed in connection with the re-approval of additives in feed and the possible establishment of MRL values in fish. Data from this study shows that there is a transfer of synthetic antioxidants from the feed to the filet, especially as regards BHT. Neither the EU nor Norway has an upper limit for BHA, BHT or EQ in food. All of the samples analysed related to farmed salmon.

Surveillance Research Programme
The surveillance programme for undesirable substances in farmed fish is part of a major surveillance programme targeted on animal foodstuffs initiated by the EU. The Norwegian Food Safety Authority is responsible for implementation of the directive in Norway. NIFES carries out the analytical work and makes the professional assessments of the results.

Download the report "Monitoring program for residues of therapeutic agents, illegal substances, pollutants and other undesirables in farmed fish".

Contac person:
Kåre Julshamn
Telephone: (+47) 99487701
E-mail: kju@nifes.no