Accumulation of Polychlorinated Dibenzo-p-Dioxins and Furans in Atlantic Cod (Gadus morhua)Cage Experiments in a Norwegian Fjord

Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) have been discharged to the Frierfjord (Eastern Norway) for 50 yr. The discharges, dominated by PCDF, were highest in the early 1970s and subsequently reduced 3-4 orders ofmagnitude to 1-2 g toxic equivalents (TEQ)/yr in 1992-2002. Atlantic cod (Gadus morhua) and semipermeable membrane devices (SPMD) were placed in cages for 6 wk in the Frierfjord and at two locations in the adjacent Langesundsfjord. The objective was to clarify the importance of PCDD/PCDF accumulation from the water directly compared to important food items. Little accumulation of PCDD and a significant accumulation of PCDF were observed in the SPMD. Accumulation of PCDF was observed in fish at Kastebukta, closest to the original source, but not at the other two stations. The PCDF concentrations detected in caged fish at Kastebukta were low compared to concentrations found in locally caught fish. Data indicate that it would take 4-55 yr to reach the PCDF-levels observed in locally caught cod if they were exposed only through water. Our results indicate that accumulation of PCDF/PCDD from prey is more important than accumulation from water.