Dioxin and PCB concentrations in salmon and herring from the Baltic Sea – impact of cooking methods, uncertainty of chemical analyses and differences between parts of the fish

A pilot study with the intention of examining how different preparation techniques of salmon and herring affects prevalence of dioxins and PCB has been conducted. For herring, smoking, frying and fermentation (fermented herring is a traditional Swedish dish) is tested. The salmon was prepared by hot-smoking, cold-smoking and curing. No clear results have emerged, but there was an early indication that by smoking herring and curing salmon, levels of dioxin-like compounds can be reduced. Future, more extensive studies are recommended.

For salmon, it was tested how dioxins and PCB distributes between different parts of the fish, and how possible differences are connected to differences in fat content between the parts. Results indicate that levels of dioxin and PCB reduces gradually from the neck-part to the tail-part of the salmon. Also, these changes were shown to be strongly related to changes in fat content between the parts.

To form an idea about how precise measurements of fat content, dioxins and PCB are, duplicated samples of muscle tissue from fish were sent to two independent accredited laboratories for analysis. Results from the lab-comparison enhanced the belief that chemical analyses of dioxins and PCB are connected to measurement error of a non-neglectable size. However, analysis of fat content seems to be related to less measurement error.