Levels of PCBs and organochlorine pesticides in various benthic species in the Belgian North sea and the Western Scheldt estuary
Context of the study
Both PCBs and organochlorine pesticides (OCPs) are known to be very persistant, to bioacumulate in lipids and to biomagnify. They are very wide spread in the environment and in biota. Many people enjoy sea food, therefore, to evaluate our exposure to these toxic chemicals, it's necessary to determine their concentrations in these animals. 
Content of the study
The study measured concentrations of PCBs and OCPs in crabs, starfish, shrimp, sand goby, sole, plaice, whiting and bib in the Western Scheldt estuary and in the Belgian part of the North Sea. This was done to evaluate their suitability for human consumption, except for sand goby and starfish, which were monitored as bioindicators. As it's known that PCBs and OCPs tend to accumulate in lipids, the lipid content of the animals was also examined.
Main results of the study
Shrimp had the lowest concentrations of PCBs: 1.5-40 ng/g (in ng PCB / g; wet weight). Bib and whiting had the highest concentrations of PCBs: 810 - 3200 ng/g and 780 - 3100 ng/g respectively. Shrimp probably had these lower concentrations because of their lower fat content (0,6% compared to 50% for bib) and their more pelagic life style. Shrimp live slightly above the seabed, which results in them having less contact with the sediment, than the other species in this study. Furthermore, shrimp occupy a lower trophic level (they eat opossum shrimp and amphipods) than most other species of the study. Crabs had a higher PCB content, because as scavengers, they eat much decaying organic material, which can be heavily polluted.
Furthermore, PCB levels were much higher in all species from the Western Scheldt estuary, than in those from the Belgian part of the North Sea.
OCPs were present at much lower concentrations than PCBs: ranging from 0.4 - 1.7 ng/g in shrimp to 22 - 410 ng/g (in ng OCP/ g; wet weight) in whiting. Here also, concentrations tended to be higher in animals from the Western Scheldt, than in those from the Belgian part of the North Sea.
The study concluded that species in the Western Scheldt estuary are highly contaminated and that this appears to be related to their proximity to Antwerp. The study could not determine whether the higher concentrations found in animals close to Antwerp only reflected historical pollution or also a present contamination.
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