Investigation of selected persistent organic pollutants in farmed Atlantic salmon (Salmo salar), salmon aquaculture feed,and fish oil components of the feed

There is extensive literature documenting the bioaccumulation of persistent organic pollutants in the marine environment, but relatively little data are available on contamination pathways in aquaculture systems such as that for farmed salmon. In recent years,the salmon industry has grown significantly in Europe. This study reports on the determination of a wide range of polychlorinated biphenyls (PCBs), organochlorine pesticides, and polybrominated diphenyl ethers (PBDEs) in farmed and wild European Atlantic salmon fish, aquaculture feeds, and fish oils used to supplement the feeds. The study confirms previous reports of relatively high concentrations of PCBs and indicates moderate concentrations of organochlorine pesticides and PBDEs in farmed Scottish and European salmon. Concentrations of the selected persistent organic pollutants varied among the samples: PCBs (salmon, 145-460 ng/g lipid; salmon feeds, 76-1153 ng/g lipid; fish oils, 9-253 ng/g lipid), S DDTs (salmon, 5-250 ng/g lipid; salmon feeds, 34-52 ng/g lipid; fish oils, 11-218 ng/g lipid), and PBDEs (salmon, 1-85 ng/g lipid: salmon feeds, 8-24 ng/g lipid; fish oils, ND-13 ng/g lipid). Comparison of the samples for all groups of contaminants, except for HCHs, showed an increase in concentration in the order fish oil < feed < salmon. Homologue profiles were similar, with an increase in contribution of hepta- and octa-PCBs in the fish, and profiles of DDTs were similar in all three types of samples. With a constant contribution to the total PCB content, the ICES 7 PCBs appear to be reliable predictors of the PCB contamination profile through all the samples. For PBDEs, BDE 47 dominated the profiles, with no significant difference in the PBDE profiles for the three matrixes. Samples with higher PCB contents generally showed higher levels of the pesticide residues, but this was not the case with the PBDEs, indicating the existence of different pollution sources.     

Lipid composition and contaminants in farmed and wild salmon

Levels of omega-3 (n-3) and omega-6 (n-6) fatty acids and lipid-adjusted concentrations of polychlorinated biphenyls (PCBs), dioxins, toxaphene, and dieldrin were determined in 459 farmed Atlantic salmon, 135 wild Pacific salmon, and 144 supermarket farmed Atlantic salmon fillets purchased in 16 cities in North America and Europe. These were the same fish previously used for measurement of organohalogen contaminants. Farmed salmon had greater levels of total lipid (average 16.6%) than wild salmon (average 6.4%). The n-3 to n-6 ratio was about 10 in wild salmon and 3-4 in farmed salmon. The supermarket samples were similar to the farmed salmon from the same region. Lipid-adjusted contaminant levels were significantly higher in farmed Atlantic salmon than those in wild Pacific salmon (F = 7.27, P = 0.0089 for toxaphene; F = 15.39, P = 0.0002 for dioxin; F > or = 21.31, P < 0.0001 for dieldrin and PCBs, with df = (1.64) for all). Levels of total lipid were in the range of 30-40% in the fish oil/fish meal that is fed to farmed salmon. Salmon, especially farmed salmon, are a good source of healthy n-3 fatty acids, but they also contain high concentrations of organochlorine compounds such as PCBs, dioxins, and chlorinated pesticides. The presence of these contaminants may reduce the net health benefits derived from the consumption of farmed salmon, despite the presence of the high level of n-3 fatty acids in these fish.     

Polychlorinated biphenyls, hexachlorobenzene, hexachlorocyclohexane isomers, and pesticide organochlorine residues in cod-liver oil dietary supplements

Levels of polychlorinated biphenyls (PCBs), hexachlorobenzene, hexachlorocyclohexane isomers (alpha, beta, gamma), and chlorinated pesticides (DDTs) in cod-liver oil used as a dietary supplement were determined. Total PCB and DDT concentrations varied from 25 to 201 ng g(-1) lipid weight basis and from 25 to 133 ng g(-1) lipid weight basis, respectively. Hexachlorobenzene contributed very little to the overall contaminant burden of dietary supplement oils, whereas hexachlorocyclohexane isomers were below the instrumental detection limits in all samples. The daily intake of PCBs and DDTs derived by the consumption of cod-liver oil at manufacturer-recommended doses varied from 0.004 to 2.01 microg/day and from 0.004 to 1.24 microg/day, respectively. Relative to some dioxin-like PCB congeners (mono-ortho PCB 105, 118, and 156; non-ortho PCB 77, 126, and 169), the intakes calculated varied from less than 0.001 to 0.74 pg of toxic equivalency values (TEQ) per kg of body weight per day. These values, although below the range of 1 to 4 pg of TEQ per kg of body weight per day set by the World Health Organization, emphasize the need for strict and continuous monitoring of fish oil contamination to reduce, as much as possible, the risks to human health.     

Polychlorinated biphenyls in salmon and salmon feed: global differences and bioaccumulation

Concentrations of 160 polychlorinated biphenyl (PCB) congeners or congener groups were determined in approximately 600 farmed Atlantic salmon from around the world and wild (ocean-caught) Pacific salmon from the Northeast Pacific. Concentrations and PCB congener profiles were analyzed to provide insight into the sources and uptake of PCBs in salmon as well as regional differences. Although total PCB concentrations in wild salmon appeared to be correlated to total lipid content, the increased proportion of total lipids in the farmed salmon could not account for the much greater PCB concentrations. We investigated the PCB congener patterns of hundreds of salmon samples using principal component analysis to further illuminate regional and species differences. Three major PCB patterns were observed, in most wild fish (except British Columbia and Oregon chinook), in farmed fish from the Atlantic, and in most farmed fish from the Pacific. The PCB congener profiles of farmed salmon often closely corresponded to a sample of commercial feed purchased in the same region, indicating that the feed is likely to be the major source of PCBs for farmed salmon. In such cases where PCB profiles in fish and feed were similar, a comparison of congener concentrations in fish and the feed showed that the majority of congeners, with some notable exceptions, were bioaccumulative to the same extent, irrespective of physical properties.     

Polychloronaphthalenes and other dioxin-like compounds in Arctic and Antarctic marine food webs

Here we report accumulation patterns of polychlorinated naphthalenes (PCNs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and pesticides (HCB, p,p'DDE) in polar organisms (polar bear from Alaskan Arctic and krill, sharp-spined notothen, crocodile icefish, Antarctic silverfish, Adélie penguin, South polar skua, and Weddell seal from the Ross Sea, Antarctica). PCNs, found in most of the samples, ranged from 1.5 pg/g in krill to 2550 pg/g in South polar skua on a wet weight basis. Lower chlorinated PCNs were the predominant congeners in organisms except skua and polar bear that showed similar PCN homologue patterns. PCDD/F concentrations were <90 pg/g wet wt in polar organisms; PCDD congeners showed peculiar accumulation patterns in different organisms. Correlation existed between PCN and PCB concentrations. PCB, HCF, and p,p'DDE levels were the highest in skua liver (11,150 ng/g wet wt, 345 ng/g wet wt, and 300 ng/g wet wt, respectively). Contribution of PCNs to 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ) was negligible (<0.1%) because of the lack of most toxic congeners. The highest TEQ was found in South polar skua liver (45 pg/g, wet weight). This is the first study to document the occurrence of PCNs in Antarctic organisms. High levels of dioxin-like chemicals in skua suggest the importance of intake via diet and migration habits, thus POP detection can be useful to trace migration behavior. Moreover, POP concentrations in penguin and skua eggs prove their transfer from the mother to eggs.     

Polychlorinated biphenyl concentrations in adult chinook salmon (Oncorhynchus tshawytscha) returning to coastal and Puget Sound hatcheries of Washington State

Identifying the source of polychlorinated biphenyls (PCBs) is the first step to eliminating contamination within anadromous salmonids and other aquatic species. We evaluated PCB concentrations in the muscle tissue of 4-year old Puget Sound and coastal hatchery Chinook salmon in an effortto identify potential locations where contamination occurs. Ten muscle samples were taken from each of two Puget Sound hatcheries and two coastal hatcheries in Washington State to determine PCB concentrations. Two technical mixtures of PCBs, Aroclor 1254 and Aroclor 1260, were measured in the tissue samples collected. Aroclor 1254 was detected in all samples, while Aroclor 1260 was detected in 16 of 40 samples. Generalized linear modeling (GLM) was used to evaluate the influence of region (Puget Sound and coast), hatchery, sex, fish length, and percent lipids on PCB concentrations. Twenty different GLMs representing multiple null hypotheses were ranked using Akaike Information Criterion (AIC). Six of the 20 models evaluated had substantial support for being the best model to describe PCB concentrations in Chinook salmon. The six models with substantial support were region and lipids; region; hatchery and lipid; region and sex; region, sex, and lipids; and region and length. Region appears to be the most influential variable explaining the variation in PCB concentrations in Chinook salmon in the Pacific Northwest. PCB concentrations in Chinook salmon muscle tissue from Puget Sound hatcheries were significantly greater (mean 49.26 microg/kg wet weight and standard deviation 40.55 microg/kg) than those from coastal hatcheries (mean 17.41 microg/kg wet weight and standard deviation 6.8 microg/kg). Our results suggest that some contamination likely occurs in the Pacific Ocean. However, a larger source likely exists within Puget Sound or along the migratory route of Puget Sound Chinook salmon. The observation of PCBs in Chinook salmon also has important implications for human health and salmon carcass supplementation.     

Bioaccumulation and toxic potencies of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in tidal flat and coastal ecosystems of the Ariake Sea,Japan

Sediment and marine biota comprising several species of tidal flat and coastal organisms were analyzed for polychlorinated biphenyls (PCBs) including non- and mono-ortho coplanar congeners and polycyclic aromatic hydrocarbons (PAHs) to examine bioaccumulation profiles and toxic potencies of these contaminants. Concentrations of PCBs in tidal flat organisms ranged from 3.6 ng/g (wet wt) in clams to 68 ng/g (wet wt) in omnivore tidal flatfishes, a discernible trend reflecting concentrations and trophic levels. In contrast, PAHs concentrations were the highest in lower trophic organisms, such as crabs and lugworms from tidal flat, whereas those in coastal fishes, squid, and finless porpoises were less than detection limit. Greater bioaccumulation of PAHs was found in lugworms and crabs, which might be due to their direct ingestion of sediment particulates absorbed with PAHs. TCDD toxic equivalents (TEQs) were calculated for PCBs and PAHs in sediments and biota. PCBs accounted for a greater proportion of total TEQs (sum(TEQs): sum of TEQ(PCB) and TEQ(PAH)) in coastal and tidal flatfishes (>95%), while PAHs occupied a considerable portion of sum(TEQs) in sediment (>97%). Interestingly, TEQ(PAH) accounted for 37% and 81% of the sum(TEQs) in crabs and clams, respectively. Benzo[b]fluoranthene was the dominant contributor to TEQ(PAH) in both the species. Considering these observations, the environmental risks of PAHs may not be ignored in benthic tidal flat organisms due to their greater bioaccumulation through sediments.     

Dioxin-like polychlorinated biphenyls in marine fish from Shandong,China, and human dietary exposure

The occurrence and human dietary exposure of 12 dioxin-like polychlorinated biphenyls (DL-PCBs) in 41 marine fish samples from Shandong Province of China were investigated. The DL-PCB congeners were extracted using automated Soxhlet extraction, purified via a composite column clean-up procedure and analysed by gas chromatography-triple quadrupole mass spectrometry. DL-PCB congeners were found in all analysed samples, with a mean concentration of 0.887 ng/g ww (wet weight). The TEQ concentrations of DL-PCBs in individual fish samples ranged from 0.011 to 9.214 pg WHO TEQ/g ww. The mean dietary intake for all fish species was 36.5 pg TEQ/kg bw/month, which was lower than the provisional tolerable monthly intake of 70 pg TEQ/kg bw/month set by the Joint FAO/WHO Expert Committee on Food Additives. To monitor the trend of DL-PCBs in fish for food safety control, it is necessary to maintain a surveillance programme.     

Flesh quality of market-size farmed and wild British Columbia salmon

This study compared the flesh quality of farmed and wild sources of British Columbia (BC) salmon with respect to concentrations of polychlorinated biphenyl compounds, polychlorinated dibenzodioxins/dibenzofurans and their associated toxic equivalents, total mercury (THg), methylmercury (MeHg), and selected fatty acids of known importance for human health viz., omega-3 (n-3) highly unsaturated fatty acids (n-3 HUFAs) and (n-6) fatty acids. Skinned fillets from known sources of farmed Atlantic, coho, and chinook salmon (n = 110) and wild coho, chinook, chum, sockeye, and pink salmon (n = 91) were examined. Atlantic salmon contained higher PCB concentrations (means, 28-38 ng/g) than farmed coho or chinook salmon, and levels in these latter species were similar to those in wild counterparts (means, 2.8-13.7 ng/g). PCB levels in Atlantic salmon flesh were, nevertheless, 53-71-fold less than the level of concern for human consumption of fish, i.e., 2000 ng/g as established by Health Canada and the U.S. Food and Drug Administration (US-FDA). Similarly, THg and MeHg levels in all samples were well below the Health Canada guideline (0.5 microg/g) and the US-FDA action level (1.0 microg/g). On average, THg in farmed salmon (0.021 microg/g) was similar to or lower than wild salmon (0.013-0.077 microg/g). Atlantic salmon were a richer source (mean, 2.34 g/100 g fillet) of n-3 HUFAs than the other farmed and wild sources of salmon examined (means, 0.39-1.17 g/100 g). The present findings support the recommended weekly consumption guidelines for oily fish species (includes all BC salmon sources) for cardio-protective benefits as made by the American Heart Association and the UK Food Standards Agency.     

Differential accumulation of polychlorinated biphenyl congeners in the aquatic food web at the Kalamazoo River Superfund site, Michigan

A series of field studies were conducted to gain a better understanding of the bioaccumulation and dynamics of polychlorinated biphenyl (PCB) congeners in the aquatic food web of the Kalamazoo River flood plain. Representative species of passerine birds, mammals, fish, aquatic plants, invertebrates, and colocated sediments were collected from areas located within submerged portions of the former Trowbridge impoundment and also from areas located at an upstream reference location. In most matrixes, total concentrations of PCBs were significantly greater in the downstream study area compared to the upstream reference location. Patterns of PCB congeners varied among trophic levels due to selective bioaccumulation of more chlorinated congeners in upper trophic level organisms. There were no statistically significant differences in total PCB concentrations among sampling grids within either site or temporally among three sampling seasons between May and September. The greatest total PCB concentrations were detected in adult tree swallows (mean = 8.7 mg/kg wet weight (ww)) and fish (mean = 4.4 mg/ kg ww) collected from the former Trowbridge impoundment. Concentrations of total 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) were greatest in egg, nestling, and adult tree swallows collected from the former Trowbridge impoundment. There was not a significant correlation between concentrations of total PCBs and TEQs at either site in the mammalian or avian food webs. The relative potency of the mixture of PCBs, expressed as the ratio of TEQs to total PCBs, increased with trophic position in the avian and mammalian aquatic food webs located within the former Trowbridge impoundment.     

Polycyclic aromatic hydrocarbons,polychlorinated biphenyls,chlorinated pesticides (DDTs), hexachlorocyclohexane,and hexachlorobenzene residues in smoked seafood

Smoked seafoods were screened for the presence of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and other organochlorine compounds. Total PAH concentrations ranged from 46.5 ng/g (wet weight) for smoked swordfish to 124.0 ng/g (wet weight) for smoked herring. Among the carcinogenic PAHs, benzo(a)pyrene ranged from undetectable levels for several smoked fish to 0.7 ng/g for Scottish salmon, dibenzo(ah)anthracene was not present in any of the samples analyzed, and benzo(a)anthracene was found in all samples and at particularly high levels in salmon (23.2 ng/g). Benzo(a)pyrene concentrations were below the tolerance limit for all samples. PCB concentrations for the different samples ranged from 2 to 30 ng/g. Chlorinated pesticides (DDTs: p,p'-DDE, p,p'-DDT, o,p'-DDT, p,p'-DDD, and o,p'-DDD) were detected at levels ranging from 0.2 ng/g (wet weight) in bluefin tuna to 17.5 ng/g (wet weight) in salmon. Hexachlorocyclohexane isomers (alphaHCH + betaHCH + gammaHCH) were present in higher amounts in eels (6.5 ng/g) than in the other smoked fish. For 40% of the samples, PCB concentrations exceeded the limit fixed by the European Union, while pesticide levels were below the maximum acceptable limit proposed by the Food and Agriculture Organization.     

Lipid reserve dynamics and magnification of persistent organic pollutants in spawning sockeye salmon (Oncorhynchus nerka) from the Fraser River, British Columbia

Pacific sockeye salmon (Oncorhynchus nerka) can travel several hundred kilometers to reach native spawning grounds and fulfill semelparous reproduction. The dramatic changes in lipid reserves during upstream migration can greatly affect internal toxicokinetics of persistent organic pollutants (POPs) such as PCBs, PCDDs, and PCDFs. We measured lipid content changes and contaminant concentrations in tissues (liver, muscle, roe/gonads) and biomarker responses (ethoxyresorufin O-deethylase or EROD activity and CYP1A levels) in two Pacific sockeye salmon stocks sampled at several locations along their spawning migration in the Fraser River, British Columbia. Muscle lipid contents declined significantly with increasing upstream migration distance and corresponded to elevated lipid normalized concentrations of PCBs and PCDD/Fs in spawning sockeye. Post-migration magnification factors (MFs) in spawning sockeye ranged between 3 and 12 and were comparable to model-predicted MFs. sigmaPCBs(150-500 ng x g(-1) lipid), sigmaPCDD/Fs (1-1000 pg x g(-1) lipid) and 2,3,7,8-TCDD toxic equivalent or TEQ levels (0.1-15 pg x g(-1) lipid) in spawning sockeye were relatively low and did not affect hepatic EROD activity/CYP1A induction. Despite a 3-fold magnification, TEQ levels in eggs of spawning Fraser River sockeye did not exceed 0.3 pg x g(-1) wet wt, a threshold level associated with 30% egg mortality in salmonids. PCBs in Fraser River sockeye are comparable to previous levels in Pacific sockeye. In contrast to Pacific sockeye from more remote coastal locations, PCDDs and PCDFs in Fraser River sockeye were generally minor components (<25%) of TEQ levels, compared to dioxin like PCB contributions (>75%). The data suggest that (i) the Fraser River is not a major contamination source of PCBs or PCDD/Fs and (ii) marine contaminant distribution, food-chain dynamics, and ocean-migration pathway are likely important factors controlling levels and patterns of POPs in returning Pacific sockeye. We estimate an annual chemical flux entering the Fraser River of up to 150 g for sigmaPCBs and 40 mg for sigmaPCDD/ Fs via returning sockeye. The results indicate that historical concentrations of PCBs and PCDD/Fs remain a potential threat to organism and ecosystem health on the west coast of Canada.     

Determination of brominated flame retardants and brominated dioxins in fish collected from three regions of Japan

The concentrations of brominated dioxins which are polybrominated dibenzo-p-dioxins/polybrominated dibenzofurans (PBDD/DFs) and mono-bromo polychlorinated dibenzo-p-dioxins/dibenzofurans, polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA) were investigated in a total of 45 fish samples collected from three regions in Japan. In the brominated dioxins, 1,2,3,4,6,7,8-heptabromodibenzofuran (HpBDF) was the most abundant congener, and it was found in seven fish samples at 0.10-25.6 pg/g wet weight (ww). The highest concentration of 1,2,3,4,6,7,8-HpBDF was found in the pike eel. Regarding other congeners, 2,3,7,8-tetrabromodibenzo-p-dioxin was detected in the sea bream at 0.02 pg/g ww, and 2,3,7,8-tetrabromodibenzofuran was detected in the conger eel at 0.03 pg/g ww. 3-Bromo-2,7,8-trichlorodibenzofuran was detected in the Sardinella zunasi and the conger eel at 0.01 pg/g ww and 0.02 pg/g ww, respectively. Using toxic equivalency factors of chlorinated dioxins, we calculated the PBDD/DFs concentrations of these fish samples at 0.001-0.256 pg TEQ/g ww. PBDEs were detected in all of the fish samples. The concentrations of total PBDEs were 0.01-2.88 ng/g ww. The seerfish and the yellowtail containd PBDEs in high concentrations. The most dominant congener in most of the fish was 2,2',4,4'-tetrabromo diphenyl ether. TBBPA was detected in 29 fish samples at 0.01-0.11 ng/g ww. The mean level of TBBPA was about one-tenth or less of the total level of PBDEs. A good correlation was obtained between total PBDEs and fat content. On the other hand, no correlation was obtained between TBBPA and fat content. The daily intakes from fish were estimated to be 0.58 ng/kg body weight (bw)/day for total PBDEs, 0.03 ng/kg bw/day for TBBPA, and 0.01 pg TEQ/kg bw/day for brominated dioxins in the case assuming that the average bw of a Japanese adult person is 50 kg and that the average fish consumption is 82 g/day. For PBDEs, the provisionally calculated value was much less than the lowest observed adverse effect level value (1 mg/kg bw/day). For brominated dioxins, the daily intake was at a very low level compared with the Japanese daily intake of polychlorinated dioxins from fish. Even if the value of PBDD/DFs is added to the amount of chlorinated dioxin exposure, it was estimated that it is less than the tolerable daily intake (4 pg TEQ/kg bw/day) in Japan.     

Associations of diet with body burden of dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs): observations on pregnant women from central Taiwan.

The aim of this study was to examine the relationship between placental polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/F) and polychlorinated biphenyls (PCBs) toxic equivalent (TEQ) levels and the consumption of various food types in pregnant women from central Taiwan. Placental PCDD/Fs and PCB congener TEQ levels were evaluated in 109 pregnant women and dietary information was obtained by questionnaire. TEQ levels of PCDD/Fs and PCBs were positively associated with age and annual family incomes (p < 0.05). PCDD/F TEQs were significantly associated with freshwater fish and dairy product consumption after adjustment for age and body mass index (BMI) (p < 0.05). For PCB TEQs, significant associations were detected for saltwater fish consumption (p < 0.05). In summary, positive correlations were found between freshwater fish and dairy product intake and PCDD/F levels, and a marginal correlation between saltwater fish intake and the body burden of PCBs in pregnant women from central Taiwan. Risk assessment of PCDD/Fs and PCB in fishery products is warranted in a future study to quantify the benefits of fish consumption during the perinatal period.     

Distribution and elimination of polychlorinated dibenzo-p-dioxins,dibenzofurans, biphenyls,and p,p'-DDE in tissues of bald eagles from the Upper Peninsula of Michigan

Liver, muscle, fat, kidney, and gall bladder of eight bald eagles (Haliaeetus leucocephalus) found dead in the Upper Peninsula of Michigan during 2000 were analyzed for the presence of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (including coplanar PCBs), p,p'-DDE, and hexachlorobenzene (HCB). Necropsy results showed that the birds suffered from peritonitis, bacterial infection, or trauma. Concentrations of PCDD/DFs in livers ranged from 23 to 4500 pg/g on a wet weight basis (wet wt), whereas the least concentrations were found in blood plasma of bald eagle nestlings (2.3-49 pg/g, wet wt). A maximum total PCB concentration of 280,000 ng/g, wet wt, was found in the liver of a dead bald eagle affected by peritonitis. The greatest concentrations of p,p'-DDE and HCB in eagle livers were 17,000 and 120 ng/g, wet wt, respectively. Eagles with elevated 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or total PCB concentrations tended to have great TCDD/TCDF or PCB126/PCB77 ratios, hypothesized to be due to induction of cytochrome P450 enzymes and subsequent metabolism of TCDF and PCB77. Concentrations of TCDD toxic equivalents (TEQs) in the tissues of bald eagles exceeded the thresholds for toxicity in a few avian species. Non-ortho coplanar PCBs accounted for 68-88% of the total TEQs in bald eagle tissues. PCDDs and PCDFs collectively accounted for, on average, 17% of the total TEQs. On the basis of the analysis of a single gall bladder with bile, biliary excretion rates of PCDDs, PCDFs, and PCBs were estimated as 0.015-0.02% per day.     

A preliminary comparison of polybrominated diphenyl ether concentrations relative to lipid content and to levels of dioxins and dioxin-like polychlorinated biphenyls in Norwegian farmed Atlantic salmon (Salmo salar)

Polybrominated diphenyl ethers (PBDEs) are environmental contaminants structurally similar to polychlorinated biphenyls (PCBs), and correlations between PBDE concentrations and concentrations of lipid, PCBs, dioxins and furans in feed and farmed Atlantic salmon filet indicate PBDEs may be derived from similar sources. PBDE concentrations (3.9 ± 0.6 ng g^?1 wet wt) in farmed Atlantic salmon correlated well with lipid content and these other halogenated contaminants, however, lower concentrations of PBDEs (1.6 ± 0.3 ng g^?1 wet wt) showed no correlation. Possible explanations for the non‐linear behaviour of PBDE concentrations in Atlantic salmon are discussed.     

Occurrence of dioxins (PCDDs,PCDFs) and polychlorinated biphenyls (PCBs) in wild,farmed and processed fish,and shellfish

Forty-eight composite samples of the most commonly consumed fish and shellfish species were prepared from up to 60 individual subsamples of each species and analysed for chlorinated dioxins (PCDD/Fs) and polychlorinated biphenyls (PCBs). These included 24 species of fresh wild fish, seven of farmed fish, seven of fresh shellfish, and ten processed fish and shellfish products. The ISO 17025-accredited analytical methodology used is consistent with the requirements given in European Commission Directive 2002/69/EC. Concentrations ranged from 0.03 ng kg^–1 PCDD/F plus PCB World Health Organization-toxic equivalent quantity (WHO-TEQ) for a sample of surimi, to approximately 6 ng kg^–1 for wild pilchards/sardines. The corresponding range for the ΣICES-6 PCBs was 0.04 μg kg^–1 to approximately 47 μg kg^–1. None of the samples showed concentrations above the European Union maximum permitted limits. Averaged PCDD/F and PCB concentrations for the two groups of farmed and wild fish show that there is little difference between the two categories, although individual species may show variations depending on factors such as the sampling location.     

Polychlorinated biphenyls (PCBs) and their congener-specific accumulation in edible fish from the Gulf of Gdańsk, Baltic Sea.

Concentrations and composition profiles of polychlorinated biphenyls (PCBs) were investigated in composite samples of 10 species of edible fish from the Gulf of Gdańsk, in the southern part of the Baltic Sea, Poland, to understand the status of contamination and possible human exposure risk. Apart from the total PCBs, planar non-ortho (IUPAC nos 77, 126, 169) and mono-ortho (nos 105, 114, 118, 123, 156, 157, 167, 189) chlorobiphenyls were also quantified and their dioxin-like toxicity assessed. The absolute total PCB concentrations in fish ranged from 43 to 490 ng g(-1) wet wt (910-11000 ng g(-1) lipids), while of TCDD TEQs of planar members were from 0.15 to 3.1 pg g(-1) wet wt (8.1-81 pg g(-1) lipids). The penta- and hexa-CBs usually comprised 70-80% of the total PCBs and were followed by hepta-, tetra- and tri-CBs, and for a specific site tri- and tetra-CBs comprised as much as 22%. Among the individual CB congeners, nos 118, 153 (+132) and 138 (+160 +163 +164) were the most abundant, while no. 110 comprised between 6.8 and 9.3% of the total PCBs in some species. Principal component analysis (PCA) was applied to examine the interdependences among CB congeners in the factor space. The PCA model and cluster analyses were further used to examine site- and species-specific differences and similarities of PCB composition, and the results are discussed. An assessed daily intake rate of TCDD TEQ of planar PCBs with the fishmeal of the Gulf of Gdańsk in the 1990s was between 78 and 96 pg per capita or between 1.3 and 1.6 pg kg(-1) body weight.     

Development and validation of protocols to differentiate PCB patterns between farmed and wild salmon

Polychlorinated biphenyl (PCB) congener patterns based on full congener PCB analyses of three farmed and five wild species of salmon from coastal British Columbia, Canada are compared using principal components analysis (PCA) and the best fit linear decomposition of the observed PCB composition in terms of Aroclor 1242, 1254, and 1260 end-members. The two complementary analysis methods are used to investigate congener composition pattern differences between species, trophic levels, feeding preferences, and farmed or wild feeding regimes, with the intent of better understanding PCB processes in both salmon and salmon consumers. PCA supports classification of PCB congeners into nine groups based on a) structure activity groups (SAG) related to the bioaccumulation potential in fish-eating mammals, b) Cl number, and c) the numbers of vicinal meta- and para-H. All three factors are needed to interpret congener distributions since SAGs by themselves do not fully explain PCB distributions. Farmed salmon exhibit very similar congener patterns that overlap the PCA and Aroclor composition of their food, while wild salmon separate into two distinct groups, with chinook and "coastal" coho having higher proportions of the higher chlorinated, Aroclor 1260 type, nonmetabolizable congeners, and chum, pink, sockeye, and "remote" coho having higher proportions of the lower chlorinated, more volatile and metabolizable Aroclor 1242 type, congeners. Wild chinook have the highest PCB and toxic equivalent (TEQ) concentrations, and the highest proportions of A1254 A1260, and PCB congeners in the most refractory SAG. Because both "coastal" and "remote" coho groups are likely to be consuming prey of similar size and trophic level, the PCB delivery mechanism (e.g., atmosphere vs runoff) apparently has more influence on the salmon PCB profile than biotransformation, suggesting that the wild chinook PCB profile is determined by feeding preference. Overall, wild salmon distributions primarily relate to trophic level, feeding preferences, and longevity, while metabolism appears at most a minor factor. The new classification protocol takes better advantage of individual congener PCB analyses and provides a better framework for understanding the PCB distributions in salmon and, potentially, the movement of individual PCB congeners through marine food chains than previous classification schemes.     

Exposure of Taiwan residents to polychlorinated biphenyl congeners from farmed, ocean-caught, and imported fish

This study is to assess PCB levels in five frequently consumed fish species in Taiwan, tilapia, milkfish, white pomfret, hairtail, and cod. Seventeen congeners were measured in fillet samples purchased from major markets in northern, central, and southern Taiwan. All 136 samples had traces of PCBs. The median concentrations were 0.18, 0.46, 0.62, 0.69, and 7.34 ng/g wet wt and 1.01, 0.28, 1.14, 5.06, and 19.3 pg-WHO-TEQ/g lipid in tilapia, milkfish, white pomfret, hairtail, and cod samples, respectively. Cod (the imported fish) had the highest wet weight PCB concentrations. The fish caught off-shore (white pomfret and hairtail) had higher levels than the farmed fish (tilapia and milkfish). The congener profiles varied among species. PCB 105/153 and 126 accounted for more than 28% and 53% of the 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (WHO-TEQs) in hairtail and cod, respectively; while PCB 156 was the major TEQ contributor in the other species. The estimated median PCB intake of the general public from consumption of the five species ranged from 0.000023 to 0.048 pg-WHO-TEQ/kg/day. It was also found that samples farmed or caught along the southern coast had higher PCB levels than those from other parts of Taiwan, indicating possible elevated PCB contamination around that area.