Level of toxins in salmon is unacceptable, say scientists

In particular, the research revealed high levels of polychlorinated biphenyls (PCBs) which persist in the environment and attack the nervous system. The increasing concern about pollution levels in salmon has already led the World Health Organisation and the EU to reduce the recommended intake to a tenth of the original levels.

“I am concerned about the dietary intake of small children. There’s a greater risk of infection and impairment of cognitive development in those children with higher intakes of PCBs,” said Dr Miriam Jacobs a nutritionist at Surrey University.

A well-known problem is that farmed salmon, with their crowded living conditions, can spread parasites to local wild populations. The intensive use of parasiticides to keep farmed fish healthy also poisons nearby marine life. In addition, farmed salmon that escape into the wild may alter the genetic make-up of wild salmon.

Last year, investigations by government scientists uncovered the illegal use of toxic chemicals on Scotland’s salmon farms. A study by the Veterinary Medicines Directorate found traces of the banned toxic neuroinsecticide, Ivermectin, in samples of farmed salmon at levels up to four times above the ‘action level’. MAFF’s Legal Branch and the Scottish Environment Protection Agency are investigating the practice. The Scottish Parliament’s Rural Affairs Committee has also discussed calls for an independent inquiry to address the environmental effects of sea cage fish farming.

The PCB problem may be caused by food fed to captive salmon, which is made from species caught all over the world and concentrated into pellets, a process that appears to increase minute amounts of toxins into a significant dose.

In Scotland the salmon farming industry is a key part of the economy, worth £260 million – more than the Highland beef and lamb industries put together – and supports 6,500 jobs. It is also the fastest-growing food sector globally.

Friends of the Earth (FoE) has called for more government research and the compulsory labelling of all farmed fish following the news.

“While the presence of cancer-causing PCBs and dioxins in wild caught fish is now well established the discovery that levels can be much higher in farmed fish is very worrying,” said Kevin Dunion, Director of FoE. “The Government must immediately step up its monitoring for these chemicals in farmed fish and work with the industry to rapidly eliminate them from all food stuffs. While we wait for these measures to be implemented all farmed fish products should be labelled to allow consumers to make an informed choice about whether they choose to buy “wild” or “farmed” fish.”

“It is nonsense to suggest levels of pollutants in farmed salmon are higher than in the wild,” Dr Jacobs told edie. “I looked at levels of PCBs and the results were comparable to those found by MAFF last year. But where MAFF considers residue levels to be acceptable I think they are not. The levels are of concern, and a large scale study is required.”

Salmon farmers are looking at ways of reprocessing fishmeal to reduce the levels of contamination, according to the Fishmeal and Oil Manufacturers Association. The industry is keen to stress the health benefits of eating the fish, which include reductions in cardiovascular disease.

Food safety expert Professor Hugh Pennington told the BBC: “Salmon is an extremely good food, and some studies show it can help prevent heart attacks. But if there are small amounts of chemicals then one must counsel moderation.”

He said one portion of salmon a week was not likely to cause harm, even to young people. But he added: “We should be monitoring the salmon perhaps more often and we should be making sure that what goes into the fish doesn’t contain these chemicals, then there isn’t a problem.”