What levels of polychlorinated biphenyls (PCBs) have been found in organic fish?
The Soil Association is aware of the problems of farmed fish being contaminated with PCBs, dioxins and other toxins (flame-retardants and mercury) that may pose a quite unacceptable health risk to consumers.
PCBs are present in all seafoods and are more frequently detected now than formerly because of more sensitive analytical techniques. Since the manufacture of PCBs was banned several decades ago, the level of PCB contamination in European diets is declining.
Any PCBs in organic fish diets are overwhelmingly contained in the marine-derived fish fraction of the diet - a by-product of fish caught for human consumption in the North Sea. PCBs and other chlorine-based pollutants (e.g. dioxins) are mainly carried dissolved in fat. Organic fish diets have lower levels of fat than conventional diets. Organic fish products are also usually lower in fat.
Conversely, environmental pollution with PCBs and similar chemicals tends to be higher in Europe than in some other parts of the world.
Because the fish element of organic feeds comes from Europe, this may mean it is more contaminated than some feed used in conventional diets - which would tend to counteract the effect of lower oil inclusion levels and the lower fat content of organic salmon and trout compared to conventional. Organic farmed salmon are likely to have similar levels of contamination to conventional.
We have a programme of monitoring with the industry to ensure that we bring the levels of contamination down very substantially. With organic feed manufacturers, we are reviewing the use of off-cuts of white fish in organic diet and investigating other sustainable sources of marine fish-meal and oil and the substitution of some of the meal and oil with vegetable sources. This will bear down further on contamination levels. Our target levels are zero and our interim levels are half those of the conventional industry. This will give an absolute level of contamination that reduces over time.