Assessment of munitions compounds in fish farms established close to dumped munitions grounds

In a previous study of fish and shellfish caught in munitions dumping grounds in 2021, traces of explosives were found in all the locations sampled. The Norwegian Food Safety Authority was accordingly concerned that fish farms located close to such munitions dumping grounds could be exposed to compounds from the dumped munitions as well. In cooperation with The Norwegian Food Safety Authority, five fish farms located close to munitions dumping grounds were selected to examine the exposure for compounds related to munitions. This report presents our results. There are no traces of explosives in any of the analyzed samples from the five fish farms collected in the period 2021–2023. At present, compounds related to munitions do not appear to be transported from the munitions dumping grounds into the fish farms. The state of the dumped munitions in the dumping grounds is not known. However, based on encounters of munitions in shallow water over the past 10 years, we estimate that the corrosion may have progressed so far that the explosive charge is partially exposed to sea water. The 2021 study detected traces of explosive compounds in fish and shellfish across all the munitions dumping grounds, including two of the dumping grounds included in this study: Botnfjorden/Leirfjorden and Malangen. This means that fish and shellfish living close to the dumped munitions are exposed to explosives, but that the contamination does not reach the fish farms located close to the dumping grounds. In one of the locations, the level of copper in fish fillet was twice as high as the general level. The concentration of copper in sediments at this location is at background level, so it is unlikely that the exposure of copper originates from the dumped munitions. The fish farm management is not aware of any sources of copper that could result in increased copper exposure close to the fish farm. The Norwegian Food Safety Authority has been notified of the result from this location, and we have recommended that a new analysis of copper is carried out at their routine sampling next time at this location. The concentrations of metals related to munitions in fish and shellfish are otherwise at the same level as in all fish farms along the Norwegian coastline. We have therefore no reason to believe that metals from the dumped munitions currently lead to an increased exposure in these fish farms.