Organohalogens and metals in marine fish and mussels and some relationships to biological variables at reference localities in Norway

The main goals of this study were to define, for the Norwegian coast, “high background” levels of micropollutants routinely monitored within the the Oslo and Paris Commission Joint Assessment and Monitoring Programme, and to reassess the present Norwegian reference levels used as the basis for a classification of environmental quality. The indicator organisms analysed as bulked/individual samples were cod (Gadus morhua, n≈1170; n≈240 for organochlorines), dab (Limanda limanda, n≈75), plaice (Pleuronectes platessa, n≈55) lemon sole (Microstomus kitt, n≈13). and blue mussels (Mytilus edulis, n≈200) collected between 1991–2000. Based on the 90–95 percentiles of measurements at localities far from point sources, we propose for liver of cod a reference level for ΣPCB7 (CBs 28, 52, 101, 118, 138, 153 and 180) of 500 μg kg−1 w.w. and further for DDE 200 μg kg−1, ΣHCHs 30 μg kg−1, HCB 20 and OCS 5 μg kg−1 w.w. In the same order the proposed reference levels for liver of dab are: 150, 60, 15, 5, and 2 μg kg−1 w.w.; and for the soft body of mussels: 3, 1, 1, 0.1 and 0.1 μg kg−1 wet weight. Reference levels of metals are 0.1 mg Hg kg−1 w.w. in fish fillet, and for Hg, Cd, Pb, Zn, Cu in mussels 0.2, 2, 3, 200 and 10 mg kg−1 d.w., respectively. Hg in fillet of cod and dab were positively correlated with length and weight. PCB levels in liver of cod and dab showed a positive but weak correlation with length, whereas no co-variation was found between PCBs and liver fat. The results of introductory recordings of polychlorinated dibenzo-p-dioxins/dibenzofurans, polychlorinated naphtalenes, Toxaphene and brominated flame retardants in liver of cod from reference sites are also presented.