Levels of some polybrominated diphenyl ether (PBDE) flame retardants along the Dutch coast as derived from their accumulation in SPMDs and blue mussels (Mytilus edulis).

Aqueous concentrations of individual brominated diphenyl ethers (BDEs) were determined for five stations in the Scheldt estuary and the North Sea along the Dutch coast using passive sampling by semipermeable membrane devices (SPMDs). Values of 0.1-5 pg l(-1) were observed. The highest levels were found in the Scheldt estuary. Concentration differences between February and October were a factor of 4-8 for BDE209, and were smaller than a factor of 2 for the other BDEs. Bioaccumulation was studied for native mussels and for mussels that were transplanted from an uncontaminated area into the Scheldt estuary for 6 weeks. Concentrations in native mussels were higher by a factor of 10 and 2 for BDEs and PCBs, respectively. Field based bioaccumulation factors (BAFs) were higher for BDEs than for PCBs by a factor of 10. Depuration experiments showed that the larger part of the BDE209 content in mussels was associated with ingested particles, whereas no such effect was observed for the other BDEs or PCBs.

Levels of hexabromocyclododecane in harbor porpoises and common dolphins from western European seas, with evidence for stereoisomer-specific biotransformation by cytochrome p450.

Commercial hexabromocyclododecane (HBCD) is a high-production-volume flame-retardant applied in polystyrene foams. It contains three stereoisomers, of which gamma-HBCD always dominates. Here we report on the levels of HBCD in blubber of harbor porpoise and common dolphin from different European seas. The highest total (sigma)-HBCD levels were measured in harbor porpoises stranded on the Irish and Scottish coasts of the Irish Sea (median concentration 2.9 microg (g of lipid)(-1)) and the northwest coast of Scotland (median concentration 5.1 microg (g of lipid)(-1)). The median levels in other areas were, for the harbor porpoise south coast of Ireland, 1.2 microg (g of lipid)(-1), for the coasts of The Netherlands, Belgium, and France north of Calais (southern North Sea), 1.1 microg (g of lipid)(-1), for the east coast of Scotland (northern North Sea), 0.77 microg (g of lipid)(-1), and, for Galicia (Spain), 0.1 microg (g of lipid)(-1). The median levels for the common dolphin were, for west coast of Ireland, 0.9 microg (g of lipid)(-1), for the French coast of the English Channel between Normandy and Brest, 0.4 microg (g of lipid)(-1), and, for Galicia, 0.2 microg (g of lipid)(-1). A subset of 10 harbor porpoise and 9 common dolphin blubber samples representing all areas were analyzed by LC/MS to determine the diastereomeric composition of their HBCD residues. All samples showed exclusively the peak of alpha-HBCD. To test if biotransformation by the cytochrome P450 system could explain the observed compositional difference with technical HBCD mixtures, a number of in vitro assays with microsomal preparations of liver were carried out. We had to revert to material stored at -80 degrees C from laboratory rats and a fresh harbor seal found dead in the Dutch Wadden Sea, since such liver samples of cetaceans were not in our possession. The in vitro assays showed that beta- and gamma-HBCDs were indeed significantly metabolized when incubated in the presence of NADPH as electron donor, compared to a set of reference samples which were identical except for the addition of NADPH. In contrast, the peak of alpha-HBCD did not decrease significantly in the presence of NADPH. In separate microsomal assays with beta- and gamma-HBCDs, new peaks of brominated compounds (signal at m/z = 79 or 81) with masses of [M + 0] were formed only when NADPH was added. This confirms the process of cytochrome P450 mediated biotransformation. Although rat and harbor seal belong to different families of the mammalia than the cetaceans, we propose that biotransformation by the cytochrome P450 system is also the most likely process to explain the exclusive accumulation of alpha-HBCD in harbor porpoise and common dolphin.

Levels of polybrominated diphenyl ether flame retardants in sediment cores from Western Europe.

The levels of 14 brominated diphenyl ether (BDE)-congeners in sediment cores from three locations in Western Europe have been determined by GC/MS (negative chemical ionization mode). Sediments from the Drammenfjord (Norway), the western Wadden Sea (The Netherlands), and the freshwater Lake Woserin (Mecklenburg-Vorpommern, Germany) showed a time-dependent pattern in the distribution of BDEs since the beginning of the industrial production of polybrominated diphenyl ether (PBDE) formulations. Two out of three commercially available PBDE formulations could be distinguished. Starting from the beginning of the 1970s, the penta-mix formulation is clearly present, but the deca-mix formulation is only present since the late 1970s. The octa-mix formulation appeared to be still absent in these sediments, as its marker-congener, BDE183, was never detected. In the cores from the western Wadden Sea and Lake Woserin, all TOC-normalized concentrations of the penta-BDE-derived congeners were leveling off in the most recent sediment layers representing 1995 and 1997, whereas those in the Drammenfjord were still increasing in 1999. The levels of BDE209, however, decreased in the most recent layer of all three cores. In Lake Woserin, the concentrations of BDE209 were much less elevated above those of the tri- to hexa-BDEs than in the other the two areas. This might be due to the absence of a significant PBDE input from sources other than the atmosphere to this rural lake. The absence of all PBDE congeners in the older layers of the three sediment cores, as well as in several 100-150-My-old layers from an extremely organic-rich marine sediment from the Kimmeridge clay formation in Dorset (UK), indicated the absence of natural production of the BDE congeners analyzed.

Levels of polybrominated diphenyl ether (PBDE) flame retardants in animals representing different trophic levels of the North Sea food Web.

The levels of individual PBDE congeners were investigated in the invertebrate species whelk (Buccinum undatum), seastar (Asterias rubens), and hermit crab (Pagurus bernhardus), the gadoid fish species whiting (Merlangius merlangus) and cod (Gadus morhua), and the marine mammal species harbor seal (Phoca vitulina) and harbor porpoise (Phocoena phocoena). These species are all important representatives of different trophic levels of the North Sea food web. All six major PBDE congeners detected (BDEs 28, 47, 99, 100, 153, and 154) are most prevalent in the commercial Penta-BDE formulation. There is no evidence for the occurrence of the Octa-BDE formulation in the North Sea food web, since its dominant congener, BDE183, was never detected. BDE209, the main congener (> 97%) in the Deca-BDE formulation, was detected only in a minority of the samples and always in concentrations around the limit of detection. Since BDE209 is often the major BDE congener in sediments from the area, the main reason for its low concentrations in biota from the North Sea seems to be a relatively low bioaccumulation potential. This can either be due to a low uptake rate of the very large molecule or a relatively rapid excretion after biotransformation. Since all invertebrates investigated are sentinel species, they are highly representative for the area of capture. The highest lipid-normalized concentrations of PBDEs in the invertebrates occurred near the mouth of the river Tees at the East coast of the UK. The geographical distribution of the PBDEs can be explained by the residual currents in the area. The direction of these currents differs between the summer and the winter season as a result of the presence or absence of vertical summer stratification of the deeper waters north of the Dogger Bank. Summer stratification results in the development of a density-driven bottom water current formed after the onset of vertical stratification of the water column in May leaving the UK coast near Flamborough Head toward the Dogger Bank. In winter, the residual currents run in a more southerly direction and follow the UK coastline. The distribution pattern of the PCBs and p,p'-DDE in the invertebrates was entirely different from that of the PBDEs, which could be expected, since the use of these organochlorines in western Europe peaked in the 1960s and 1970s but has been forbidden more than two decades ago, whereas the production and use of the penta-BDE formulation is of a more recent origin. The higher trophic levels of the North Sea food web were represented by the predatory gadoid fish species whiting and cod and the marine mammal species harbor seal and harbor porpoise. The lipid-normalized levels of the six major PBDE congeners in fish were similar to the levels in the invertebrates, but a biomagnification step in concentrations of generally more than an order of magnitude occurred from gadoid fish to marine mammals. Based on the limited number of samples, no differences could be observed between harbor seal and harbor porpoise. In summary, the results in three species of sentinel invertebrates from a network of stations covering a major part of the North Sea basin showed that the estuary of the river Tees at the UK East coast is a major source for tri- to hexa-PBDEs. Throughout the food-chain, the most marked increase in (lipid-normalized) levels of all six PBDE congeners occurred from predatory (gadoid) fish to marine mammals, agreeing with the transition from gill-breathing to lung-breathing animals. This has serious consequences for the route of elimination of POPs, since their elimination from the blood into the ambient seawater via the gill-membrane is no longer possible.

Distribution and fate of HBCD and TBBPA brominated flame retardants in North Sea estuaries and aquatic food webs.

Tetrabromobisphenol A (TBBPA) and hexabromocyclododecane diastereoisomers (alpha-, beta/-, and gamma-HBCD) were investigated in effluents from sewage treatment works, landfill leachates, sediments, and food web organisms of the North Sea basin. Residues were quantified by liquid chromatography-mass spectrometry. Both flame retardants were enriched in sewage sludges, where a maximum total (sigma) HBCD concentration of 9.1 mg/kg (dry weight; d.w.) was found; TBBPA was at levels of 102 microg/kg. Landfill leachates from The Netherlands showed up to 36 mg (sigmaHBCD)/ kg (d.w.). gamma-HBCD dominated isomeric profiles in sediments, and concentrations were elevated near to a site of HBCD manufacture. alpha-HBCD was the primary congener detected in marine mammals; however, very few samples exhibited TBBPA. sigmaHBCD ranged from 2.1 to 6.8 mg/kg (lipid weight; l.w.) in liver and blubber of harbor porpoises (Phocoena phocoena) and seals (Phoca vitulina). TBBPA levels in cormorant (Phalacrocorax carbo) livers were up to 1 order of magnitude lower compared to sigmaHBCD. HBCD in eels (Anguilla anguilla) from the Scheldt basin (Belgium) reflected the spatial distribution of concentrations in local sediments. This study shows evidence of HBCD bioaccumulation at the trophic level and biomagnification in the ascending aquatic food chain, and these findings justify risk assessment studies at the ecosystem level.