Perfluorinated compounds are very stable, making their degradation in nature a slow process. As a consequence, the PFC concentration will have a tendency to magnify up the food chain. Analyses carried out by the National Institute of Nutrition and Seafood Research (NIFES) in 2007 have shown that the amount of PFC is very low in seafood samples examined so far. Due to the compounds unique properties the greatest concentrations are found in fish blood, liver and kidneys. In samples of whole capelin and shrimp NIFES have found low concentrations of several PFCs, and filets of, for example, farmed salmon has levels below what we can quantify to date.
What are perfluorinated compounds?
PFC encompasses a large group of man-made compounds with unique properties. The most known perfluorinated compound from everyday life is probably the perfluorinated polymer Teflon®, with the original chemical name polytetrafluoroethylene (PTFE). Teflon is used as a “non-stick” coating in frying pans and baking tins. Perfluorinated compounds are very stable and they are difficult to mix with both water and oil. These unique properties have made them applicable for many purposes including as part of lubricants, lock oils, impregnation and fire fighting foams.
Why examine PFC in seafood?
Studies have shown that a number of perfluorinated compounds, e.g. perfluorooctanesulphonic acid (PFOS) and perfluorooctanoic acid (PFOA), may have harmful effects on organisms at high concentrations. Norway’s aim is to halt or significantly reduce the emission of the most abundant perfluorinated compounds by 2010. PFOS is already prohibited for use in fire fighting foams, textiles and preservatives. Therefore, it is important to monitor the amount and the prevalence of the most widely used perflourinated compounds in nature. NIFES analyses fish and other seafood for PFC and other contaminants to document their levels and assess their influence on seafood safety.
How to analyse PFC in seafood?
Samples of fish and other seafood from Norwegian seas, were collected, in collaboration with the Institute of Marine Research. When the samples arrive at NIFES, the relevant part of the sample, for example the fish filet, is homogenised. In the laboratory, a small part of the sample is weighed, followed by the addition of a solvent which extracts the perfluorinated compounds. Fat, proteins and carbohydrates are then removed from the solvent, which contains the perfluorinated compounds. Finally, the remaining liquid is analysed by an ultra performance liquid chromatography system, which separates the different perfluorinated compounds in the sample. The separated perfluorinated compounds are quantified using a double mass spectrometer.