Due to an increased use of the delousing agents in fish farming in 2009, the National Institute of Nutrition and Seafood Research has examined additional filets from a total of 205 farmed fish for residues of diflubenzuron and teflubenzuron, on behalf of the Norwegian Food Safety Authority.

These extra samples are in addition to the regular surveillance of these substances in fish farming. The results of the additional analyses showed no residues of diflubenzuron or teflubenzuron, consistent with the result from the regular surveillance programme.

The samples analysed for diflubenzuron and teflubenzuron were taken from a coastal region where these delousing agents had been used. Samples were taken both from farms where the fish had undergone treatment with diflubenzuron and teflubenzuron, and from farms where the fish had not undergone such treatment. Thus it was documented that treated fish did not contain concentration of these substances above the maximum residue limits (MRL), and to confirm that unregistered use of these delousing agents did not occur.

The samples were collected during the autumn of 2009 and at the beginning of 2010. The analytical methods used are very sensitive and capable of detecting one hundredth of the internationally set MRL of diflubenzuron and teflubenzuron.

These additional analyses showed no residues of diflubenzuron and teflubenzuron in the fish filets, consistent with the previous monitoring.