Trends of perfluorochemicals in Greenland ringed seals and polar bears: Indications of shifts to decreasing trends

Time-series of perfluorinated alkylated substances (PFASs) in East Greenland polar bears and East and West Greenland ringed seals were updated in order to deduce whether a response to the major reduction in perfluoroalkyl production in the early 2000s had occurred. Previous studies had documented an exponential increase of perfluorooctane sulphonate (PFOS) in liver tissue from both species. In the present study, PFOS was still the far most dominant compound constituting 92% (West Greenland ringed seals), 88% (East Greenland ringed seals) and 85% (East Greenland polar bears). The PFOS concentrations increased up to 2006 with doubling times of approximately 6 years for the ringed seal populations and 14 years in case of polar bears. Since then a rapid decrease has occurred with clearing half-lives of approximately 1, 2 and 4 years, respectively. In polar bears perfluorohexane sulphonate (PFHxS) and perfluorooctane sulphonamide (PFOSA) also showed decreasing trends in recent years as do perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnA). For the West Greenland ringed seal population perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), PFDA and PFUnA peaked in the mid 2000s, whereas PFNA, PFDA and PFUnA in the East Greenland population have been stable or increasing in recent years. The peak of PFASs in Greenland ringed seals and polar bears occurred at a later time than in Canadian seals and polar bears and considerably later than observed in seal species from more southern latitudes. We suggest that this could be explained by the distance to emission hot-spots and differences in long-range transport to the Arctic.     

Debrominated, hydroxylated and methoxylated metabolism in maize (Zea mays L.) exposed to lesser polybrominated diphenyl ethers (PBDEs)

A hydroponic experiment was conducted to investigate the debrominated, hydroxylated and methoxylated metabolism of polybrominated diphenyl ethers (PBDEs, BDE-15, -28 and -47) in maize. A total of six debrominated metabolites (de-PBDEs), seven hydroxylated PBDEs (OH-PBDEs, including two unidentified OH-di-PBDEs and one unidentified OH-tri-PBDE) and four methoxylated PBDEs (MeO-PBDEs) were determined in the exposed plants. The metabolic products were detected in maize only after 12 h of exposure to the PBDEs. However, the concentration of each type of the metabolites (de-PBDEs, OH-PBDEs or MeO-PBDEs) decreased at the later exposure time, possibly due to further metabolism. The removal of a bromine atom or the introduction of a hydroxyl/methoxy group was easier at the ortho-positions on the biphenyl structure than at the para-positions. Concentration ratios of the total debrominated, hydroxylated or methoxylated metabolites to the parent congener (BDE-28 or -47) generally followed the order of leaves > stems ? roots, and MeO-PBDEs > de-PBDEs ? OH-PBDEs. These results suggest that metabolism occurred preferentially in leaves and stems than in roots. Less transformation and shorter elimination half-life of OH-PBDEs would contribute to the lower concentrations of OH-PBDEs than of de-PBDEs or MeO-PBDEs in maize.     

Levels and distribution of polybrominated diphenyl ethers in various tissues of birds of prey

In the present study, concentrations and tissue distribution of polybrominated diphenyl ethers (PBDEs; IUPAC # 28, 47, 99, 100, 153, 154, 183, and 209) were examined in brain, adipose tissue, liver, muscle, and serum of birds of prey. Median SigmaPBDE levels (BDE 28-183) in the tissues of sparrowhawks ranged from 360 to 1900 ng/g lipid weight (lw), which was in general one order of magnitude higher than in the tissues of common buzzards (26-130 ng/g lw). There were no differences in PBDE congener patterns between the various tissues within individuals of a certain species. Inter-species differences in PBDE patterns and in particular the percentage of BDE 99, 100 and 153 were, however, pronounced between sparrowhawk and common buzzard. BDE 209 was detected in nearly all serum and in some liver samples, but not in any other tissues. This observation suggests that exposure to BDE 209 is low or that this congener is poorly accumulated. Passive (lipid content related) diffusion could not completely describe the PBDE tissue distribution, e.g. the lowest PBDE-load was measured in brain, a fairly lipid rich tissue.     

Linear and branched perfluorooctane sulfonate (PFOS) isomer patterns differ among several tissues and blood of polar bears

Perfluorooctane sulfonate (PFOS) is a globally distributed persistent organic pollutant that has been found to bioaccumulate and biomagnify in aquatic food webs. Although principally in its linear isomeric configuration, 21–35% of the PFOS manufactured via electrochemical fluorination is produced as a branched structural isomer. PFOS isomer patterns were investigated in multiple tissues of polar bears (Ursus maritimus) from East Greenland. The liver (n = 9), blood (n = 19), brain (n = 16), muscle (n = 5), and adipose (n = 5) were analyzed for linear PFOS (n-PFOS), as well as multiple mono- and di-trifluoromethyl-substituted branched isomers. n-PFOS accounted for 93.0 ± 0.5% of Σ-PFOS isomer concentrations in the liver, whereas the proportion was significantly lower (p < 0.05) in the blood (85.4 ± 0.5%). Branched isomers were quantifiable in the liver and blood, but not in the brain, muscle, or adipose. In both the liver and blood, 6-perfluoromethylheptane sulfonate (P6MHpS) was the dominant branched isomer (2.61 ± 0.10%, and 3.26 ± 0.13% of Σ-PFOS concentrations, respectively). No di-trifluoromethyl-substituted isomers were detectable in any of the tissues analyzed. These tissue-specific isomer patterns suggest isomer-specific pharmacokinetics, perhaps due to differences in protein affinities, and thus differences in protein interactions, as well transport, absorption, and/or metabolism in the body.     

Tissue distribution of planar and non-planar chlorobiphenyls, 4,4'-DDE and hexachlorobenzene in sheep and lambs

The bioconcentration and distribution pattern of individual PCB congeners (IUPAC Nos: -54, -80, -155 and -169) and organochlorine pesticides (HCB and 4,4'-DDE) in blood, adipose tissue, liver and brain were examined in sheep two months after administration and in their offspring continuously exposed during the two months lactation period. Analyses were performed by high resolution gas chromatography. The levels of individual organochlorines varied significantly between tissues; the tissue/blood ratio (on a fat basis) varied by two orders of magnitude for individual congeners. The bioconcentration of the toxic planar PCB-169 congener was the highest in the liver and the lowest in the brain of the sheep.     

Seasonal variations of hydroxylated and methoxylated brominated diphenyl ethers in blue mussels from the Baltic Sea

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) found at high levels in the Baltic biota are mainly natural products, but can also be formed through metabolism or abiotic oxidation of polybrominated diphenyl ethers (PBDEs). The formation of OH-PBDEs is of concern since there is growing evidence of phenolic toxicity. This study investigates seasonal variations in levels of OH-PBDEs and MeO-PBDEs, focusing on an exposed species, the blue mussel (Mytilus edulis), sampled in the Baltic Sea in May, June, August and October of 2008. Both the OH-PBDE and MeO-PBDE levels in the mussels showed seasonal variations from May to October, the highest concentration of each congener appearing in June. The seasonal variation was more marked for OH-PBDEs than in MeO-PBDEs, but all congeners showed the same trends, except 6-MeO-BDE47 and 2′-MeO-BDE68, which did not significantly decline in concentrations after June. Biotic or abiotic debromination is suggested as a possible reason for the rapid decrease in methoxylated penta- and hexa-BDE concentrations observed in blue mussels from June to August, while the tetraBDE concentrations were stable. In addition, 1,3,7/1,3,8-tribrominated dibenzo-p-dioxins showed the same seasonal variation. The seasonal variations indicates natural formation and are unlikely to be due to transformation of anthropogenic precursors. The levels of PBDEs were fairly constant over time and considerably lower than those of the OH-PBDEs and MeO-PBDEs. The timing of the peaks in concentrations suggests that filamentous macro-algae may be important sources of these compounds found in the blue mussels from this Baltic Sea location.     

Debrominated,hydroxylated and methoxylated metabolism in maize (Zea mays L.) exposed to lesser polybrominated diphenyl ethers (PBDEs)

A hydroponic experiment was conducted to investigate the debrominated, hydroxylated and methoxylated metabolism of polybrominated diphenyl ethers (PBDEs, BDE-15, -28 and -47) in maize. A total of six debrominated metabolites (de-PBDEs), seven hydroxylated PBDEs (OH-PBDEs, including two unidentified OH-di-PBDEs and one unidentified OH-tri-PBDE) and four methoxylated PBDEs (MeO-PBDEs) were determined in the exposed plants. The metabolic products were detected in maize only after 12 h of exposure to the PBDEs. However, the concentration of each type of the metabolites (de-PBDEs, OH-PBDEs or MeO-PBDEs) decreased at the later exposure time, possibly due to further metabolism. The removal of a bromine atom or the introduction of a hydroxyl/methoxy group was easier at the ortho-positions on the biphenyl structure than at the para-positions. Concentration ratios of the total debrominated, hydroxylated or methoxylated metabolites to the parent congener (BDE-28 or -47) generally followed the order of leaves > stems ≫ roots, and MeO-PBDEs > de-PBDEs ≫ OH-PBDEs. These results suggest that metabolism occurred preferentially in leaves and stems than in roots. Less transformation and shorter elimination half-life of OH-PBDEs would contribute to the lower concentrations of OH-PBDEs than of de-PBDEs or MeO-PBDEs in maize.     

Organohalogen compounds and their metabolites in the blood of Japanese amberjack (Seriola quinqueradiata) and scalloped hammerhead shark (Sphyrna lewini) from Japanese coastal waters

Information on accumulation of polychlorinated biphenyl metabolites (OH-PCBs) and hydroxylated polybrominated diphenyl ethers (OH-PBDEs) in the blood of marine fish is limited. The present study, we determined the residue levels and patterns of PCBs, OH-PCBs, PBDEs, OH-PBDEs and methoxylated PBDEs (MeO-PBDEs) in the blood collected from scalloped hammerhead shark (Sphyrna lewini) and Japanese amberjack (Seriola quinqueradiata), species of predatory fish at Japanese coastal waters. The predominant homologues found in Japanese amberjacks were mono- and di-chlorinated OH-PCBs, and scalloped hammerhead sharks were octa-chlorinated OH-PCBs. The predominant OH-PCB isomers were lower-chlorinated OH-PCBs such as 6OH-CB2 and 2'OH-CB9 in Japanese amberjacks. This result suggests that exposure of Japanese amberjacks to lower-chlorinated OH-PCBs might be from the ambient aquatic environment. In scalloped hammerhead sharks, 4,4'diOH-CB202, 4OH-CB201 and 4OH-CB146 were the predominant isomers accounting for approximately 60% of the total OH-PCBs. The predominant MeO-PBDE isomers were 6MeO-BDE47 followed by 2'MeO-BDE68 in both species. As for OH-PBDE isomers, 6OH-BDE47 was predominant followed by 2'OH-BDE68 in Japanese amberjacks and scalloped hammerhead sharks. Residue levels of ΣMeO-PBDEs and ΣOH-PBDEs showed a significant positive correlation (p=0.029). This result suggests that MeO-PBDEs and OH-PBDEs share a common source or a metabolic pathway in fishes. Characteristic differences found in the profiles of OH-PCBs and OH-PBDEs in Japanese amberjack and scalloped hammerhead shark show the need for further studies on the differences in exposure profiles, metabolic capacities and toxic effects in fish.     

Body burdens and tissue concentrations of organochlorines in polar bears (Ursus maritimus) vary during seasonal fasts

Lipophilic organochlorines (OCs) are ingested by mammals through their foods and are generally stored in adipose tissue depots. For some species, such as polar bears, the size of these depots can fluctuate seasonally by several-fold. However, the effect of these fluctuations on the fate of stored OCs in an animal with such labile lipid depots is unknown. We determined the whole body burden and tissue concentrations of OCs in free-ranging polar bears categorized by age (cubs-of-the-year, yearlings and adults) and sex before and after a fast averaging 56 days. Adipose tissue, plasma, and milk samples were analysed for sum of chlorobenzenes (sigma-ClBzs), hexachlorocyclohexanes (sigma-HCHs), chlordanes (sigma-CHLORs), dichlorodiphenyltrichloroethane compounds (sigma-DDTs) and polychlorinated biphenyls (sigma-PCBs). Decline in body mass during fasting ranged from 0.2 kg/day for cubs-of-the-year to 0.9 kg/day for sub-adult and adult males. Although all bears showed a decline in both lipid and lean mass during fasting, patterns of OC whole body burden changes were not consistent among compounds and bear classes. The burdens of sigma-DDTs declined by 11-50% for most bears during fasting, those of sigma-CHLORs declined by 67% during fasting in sub-adult and adult males but remained constant for all females, indicating male-specific metabolism of sigma-CHLORs. As fat depots became depleted, OC concentrations in the remaining adipose tissue varied; sigma-DDTs and sigma-HCHs declined while those of sigma-CHLORs and sigma-PCBs generally increased. Thus. within a 3-4 month fast, most polar bears were able to significantly rid their adipose tissue of sigma-DDTs and sigma-HCHs. Burdens of sigma-CHLORs (except males), sigma-ClBzs and sigma-PCBs remained constant for all classes of bears, therefore there was no significant excretion or metabolism during the fast of the specific congeners in these compound classes typically found in polar bears. The ratio of plasma/adipose tissue and milk/adipose tissue OC concentrations was the same for before and after the fast indicating that OC concentrations in polar bears are probably at a steady state among various body compartments. Concentrations of sigma-CHLORs and sigma-PCBs in milk almost doubled during the fast. As a consequence of this rise in milk OC concentrations, the whole body concentrations of these compounds increased in nursing cubs. Since developing young may be susceptible to the effects of environmental contaminants, the increased exposure of nursing cubs to OCs during a fast by their mothers is noteworthy.     

Hydroxylated and methoxylated polybrominated diphenyl ethers and polybrominated dibenzo-p-dioxins in red alga and cyanobacteria living in the Baltic Sea

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) are present in the ecosystem of the Baltic Sea. OH-PBDEs are known to be both natural products from marine environments and metabolites of the anthropogenic polybrominated diphenyl ethers (PBDEs), whereas, MeO-PBDEs appear to be solely natural in origin. Polybrominated dibenzo-p-dioxins (PBDDs) are by-products formed in connection with the combustion of brominated flame retardants (BFRs), but are also indicated as natural products in a red alga (Ceramium tenuicorne) and blue mussels living in the Baltic Sea. The aims of the present investigation were to quantify the OH-PBDEs and MeO-PBDEs present in C. tenuicorne; to verify the identities of PBDDs detected previously in this species of red alga and to investigate whether cyanobacteria living in this same region of the Baltic Sea contain OH-PBDEs, MeO-PBDEs and/or PBDDs. The red alga was confirmed to contain tribromodibenzo-p-dioxins (triBDDs), by accurate mass determination and additional PBDD congeners were also detected in this sample. This is the first time that PBDDs have been identified in a red alga. The SigmaOH-PBDEs and SigmaMeO-PBDEs concentrations, present in C. tenuicorne were 150 and 4.6 ng g(-1) dry weight, respectively. In the cyanobacteria 6 OH-PBDEs, 6 MeO-PBDEs and 4 PBDDs were detected by mass spectrometry (electron capture negative ionization (ECNI)). The PBDDs and OH-PBDEs and MeO-PBDEs detected in the red alga and cyanobacteria are most likely of natural origin.     

PCB levels and congener patterns from Korean municipal waste incinerator stack emissions

Congener specific polychlorinated biphenyl (PCB) data from the stack gas of nine Korean municipal waste incinerators was used to determine characteristic congener patterns of emitted PCBs. Principal component analysis revealed three classes of incinerators according to their pattern of PCB congener emissions: those resembling the background sampling material; those producing large quantities of a few tetra-chlorinated congeners; those producing large proportions of mono (MO-) and non-ortho (NO-) congeners relative to di-ortho (DO-) levels. Also, correlations between individual PCB congeners and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) were discovered for several NO-PCBs and tetra and penta chlorinated PCDFs. Full PCB congener data is presented along with operating conditions for each incinerator.     

PCB congener distributions in muscle,liver and gonad of Fundulus heteroclitus from the lower Hudson River Estuary and Newark Bay

Gradients in sediment polychlorinated biphenyl (PCB) concentrations and PCB congener profiles exist along the Hudson River (NY, USA). We evaluated site and tissue differences in PCB concentration and congener profiles in resident mummichog (Fundulus heteroclitus) collected from PCB-contaminated sites in the lower Hudson River and the New York/New Jersey Harbor Estuary. Fish were collected from three PCB-contaminated sites Piermont Marsh (P), Iona Marsh (I), and Newark Bay (NB), and from two reference sites (Flax Pond, NY; Succotash Salt Marsh, RI). Congener profiles were statistically analyzed using principal component analysis (PCA) and general linear model (GLM) profile analysis. Contaminated fish had PCB tissue concentrations approximately 10-fold higher than those of reference fish. There were no site differences in PCB body burden (all tissues combined) among the contaminated site fish. However, relative PCB concentration did differ between organs: NB fish (gonad=liver>muscle); I and P fish (gonad>liver>muscle). In contrast to PCB content, PCB congener profiles did show site differences; NB mummichog being depleted in the less chlorinated congeners relative to I and P fish, likely reflecting different PCB sources to these populations. Within a site, however, PCB congener patterns were similar between liver, gonad and muscle. In conclusion, PCA and GLM analyses gave complementary results, both analyses indicating differences in site, but not tissue, distributions of PCB congeners. This study also demonstrates that unlike congener profiles, total PCB content does differ dramatically amongst tissues and further, that PCB differences among tissues (gonad vs. liver vs. muscle) can vary with site.     

Age and seasonal variability of polybrominated diphenyl ethers in free-ranging East Greenland polar bears (Ursus maritimus)

Polybrominated diphenyl ethers (PBDEs) were analysed in adipose tissue from 92 East Greenland polar bears (Ursus maritimus) sampled during 1999-2001. Mean SigmaPBDE concentrations were 70 ng/g lipid weight (lw) (range: 22-192 ng/g lw) and showed no relationship with age or sex. Of the 32 analysed PBDE congeners; BDE47, BDE153, BDE99 and BDE100 dominated, and comprised 99.6% of the SigmaPBDE concentration. The SigmaPBDE concentration had a highly significant correlation with SigmaPCB, SigmaCHL, dieldrin, HCB and SigmaHCH concentrations. We found a seasonal pattern of median SigmaPBDE concentration with 1.2 to 1.8 times higher concentrations in March to July than the rest of the year. The seasonal variation also provides a clue to the seasonal exposure, bio-availability, toxic exposure and degradation. We suggest that future geographical PBDE data comparisons may not need corrections for sex or age, but such data sets should be corrected for seasonal variability, using the presented correctional trigonometric regression.     

Anthropogenic and naturally occurring polybrominated phenolic compounds in the blood of cetaceans stranded along Japanese coastal waters

We determined the residue levels and patterns of hydroxylated polybrominated diphenyl ethers (OH-PBDEs), and related compounds, such as PBDEs, methoxylated PBDEs (MeO-PBDEs), and bromophenols (BPhs) in the blood of eleven cetacean species stranded along the Japanese coasts. The dominant OH- and MeO-PBDE isomers found in all cetaceans were 6OH-BDE47 and 6MeO-BDE47. Additionally, 2,4,6-triBPh was dominant isomer in all cetaceans. In contrast, specific differences in the distribution of para- and meta- OH-PBDE isomers and some BPhs (potential PBDEs metabolites) were found among the cetaceans.Residue levels of ΣMeO-PBDEs and 6OH-BDE47 + 2′OH-BDE68, and 2,4,6-triBPh and 6OH-BDE47 + 2′OH-BDE68 showed a significant positive correlation. These results may suggest that the large percentages of OH-PBDEs, MeO-PBDEs and 2,4,6-triBPh might share common source (i.e. biosynthesis by marine organisms), or metabolic pathway in cetacean species. Significant correlations were found between the concentrations of BDE99 and 2,4,5-triBPh. This result suggested that 2,4,5-triBPh in cetaceans could be a metabolite of BDE99.     

Synthesis and tentative identification of novel polybrominated diphenyl ether metabolites in human blood

Hydroxylated polybrominated diphenyl ethers (OH-PDBEs) are exogenous, bioactive compounds that originate, to a large extent, from anthropogenic activities, although they are also naturally produced in the environment. In the present study nine new authentic OH-PBDE reference standards and their corresponding methyl ether derivatives (MeO-PBDEs) were synthesised and characterised by NMR spectroscopy and mass spectrometry. Seven of the authentic reference standards prepared were thereafter tentatively identified in a pooled human blood sample. The tentatively identified OH-PBDEs were 3-hydroxy-2,2',4,4',6-pentabromodiphenyl ether, 3'-hydroxy-2,2',4,4',6-pentabromodiphenyl ether, 3-hydroxy-2,2',4,4',5-pentabromodiphenyl ether, 3-hydroxy-2,2',4,4',5,6'-hexabromodiphenyl ether, 3'-hydroxy-2,2',4,4',5,6'-hexabromodiphenyl ether, 3-hydroxy-2,2',4,4',5,5'-hexabromodiphenyl ether and 4-hydroxy-2,2',3,4',5,5',6-heptabromodiphenyl ether. An additional seven OH-PBDEs were tentatively identified in the pooled human blood sample, of which one OH-PBDE, 4'-hydroxy-2,2',4,5,5'-pentabromodiphenyl ether, has not been identified in human blood before. The identification was performed using gas chromatography-mass spectrometry (GC-MS) recording the bromine ions m/z 79, 81. The tentative identification was supported by the peaks relative retention times (RRTs) compared to authentic references on two GC columns of different polarities for the hexa-, and heptabrominated OH-PBDEs, and three different GC columns for the pentabrominated OH-PBDEs. The OH-PBDE congeners most likely originate from human metabolism of a flame retardant, i.e. polybrominated diphenyl ethers (PBDEs), due to the relatively high concentrations of PBDEs in the same human blood sample and the fact that these PBDEs could form the tentatively identified OH-PBDEs via metabolic direct hydroxylation or via 1,2-shift.     

PCBs and other organochlorines in human tissue samples from the Welsh population: I--Adipose

The general exposure of humans to polychlorinated biphenyls (PCBs) and SigmaDDT (i.e., p,p'-DDT + p,p'DDE = p,p'-DDD) in Wales (UK) was determined through the analysis of adipose tissue samples collected from 75 individuals during post-mortem examinations in 1990-1991. Fifty PCB congeners were screened, of which 29 were identified in most of the samples. Congener IUPAC numbers 138, 153 and 180 were the most abundant compounds, accounting for an average of 55% of the SigmaPCB congeners analysed. SigmaPCB concentrations varied between 0.2 and 1.8 microg g(-1) of adipose tissue and were positively correlated with the donors age and negatively associated with the percentage of lipid in the adipose tissue. A progressive change in the congener pattern was noted with increasing subject age. Tissue from older individuals generally contained a relatively high proportion of the more persistent and higher chlorinated congeners. SigmaDDT concentrations ranged from 0.11 to 5.6 microg g(-1) adipose tissue, with p,p'-DDE contributing 96% towards the SigmaDDT concentration. SigmaDDT levels were also positively correlated with age. No significant differences in the SigmaPCB and SigmaDDT concentrations were noted between males and females, between people living in rural and urban locations or with the subjects' body weight at the time of their death.     

PCBs, DDTs and methyl sulphone metabolites in various tissues of harbour porpoises from Swedish waters

Aryl methyl sulphones of polychlorinated biphenyls (PCBs) and 3-p,p'-DDE (MeSO(2)-PCBs and 3-MeSO(2)-p,p'-DDE), PCBs and Sigma DDTs were analysed in five different tissues (blubber, nuchal fat, liver, muscle, brain) of adult male harbour porpoises from the west coast of Sweden. Two different methods for MeSO(2)-PCBs and 3-MeSO(2)-p,p'-DDE determination were used, gas chromatography-mass spectrometry and gas chromatography-atomic emission detection. Highest concentrations of Sigma MeSO(2)-PCBs were found in liver (0.15-0.49 microg/g lipid wt.), which corresponded to 2.0-2.8% of the Sigma PCBs concentrations. Blubber and nuchal fat showed Sigma MeSO(2)-PCB concentrations that were three to five times lower than those in liver. Concentrations of 3-MeSO(2)-p,p'-DDE in liver, muscle and brain corresponded to 0.26-4.6% of the p,p'-DDE concentrations, while in blubber and nuchal fat, 3-MeSO(2)-p,p'-DDE constituted 0.033-0.21% of p,p'-DDE. The different tissues analysed showed similar levels (lipid wt.) of Sigma PCBs and Sigma DDTs, except for brain that had almost 10 times lower levels compared to the other tissues. Using the Sigma PCBs/Sigma MeSO(2)-PCBs ratio to estimate MeSO(2)-PCB formation and secondary metabolism capacity, the harbour porpoise showed a relatively low capacity of MeSO(2)-PCB formation compared to other small toothed whales and seals. Blubber sampled from five different anatomical locations showed that concentrations of contaminants may be unevenly distributed in blubber in certain animals. This should be taken into account when choosing sampling sites on the porpoise.     

Studies on the distribution of beta- and gamma-isomers of hexachlorocyclohexane in rat tissues

A study of the comparative distribution pattern of beta- and gamma-isomers of hexachlorocyclohexane (HCH) in albino rat tissues as a function of duration of treatment at two dose levels revealed different accumulation patterns for the two isomers in tissues. In general, the accumulation pattern was found to be in the order: fat greater than kidney greater than lungs greater than liver greater than muscle greater than heart greater than spleen greater than brain greater than blood for beta-HCH and fat greater than brain greater than kidney greater than muscle greater than lungs greater than heart greater than spleen greater than liver greater than blood for gamma-HCH. The tissue accumulation of beta-isomer was always greater than that of gamma-isomer in any tissue except in brain. Brain beta-HCH residue levels were relatively lower than in many other tissues except blood, whereas brain gamma-HCH concentration was only next to fat. A higher dose or a longer period of treatment generally produced a more marked elevation of tissue residue levels in beta-HCH fed rats, but not in gamma-HCH treated animals.     

Polybrominated diphenyl ethers and their methoxylated and hydroxylated analogs in Brown Bullhead (Ameiurus nebulosus) plasma from Lake Ontario

Polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs) and hydroxylated PBDEs (OH-PBDEs) were detected and quantified in Brown Bullhead (Ameiurus nebulosus) from Lake Ontario. Samples were collected in 2006 from three different locations near the city of Toronto: Frenchman’s Bay, Toronto Island, and Tommy Thompson Park. A total of 117 plasma samples were pooled into 19 samples, separating males and females by site of capture. Pooled samples were analyzed for 36 PBDEs, 20 MeO-PBDEs and 20 OH-PBDEs, but only six PBDEs, five MeO- and eight OH-compounds were confirmed against standards currently available. These peaks were quantified as “identified” peaks, while peaks matching ion ratios but not matching the retention time of the available standards were quantified as “unidentified” peaks. Both “identified” and “unidentified” concentrations were combined to obtain a total concentration. No significant variations were obtained for total PBDE concentrations, ranging from 3.33 to 9.02 ng g^?1 wet weight. However, OH- and MeO-PBDE totals ranged over 1 order of magnitude among the samples (not detected – 3.57 ng g^?1 wet weight for OH-PBDEs and not detected ?0.10 ng/g wet weight for MeO-PBDE). The results of this study suggested that these compounds are ubiquitous in biota. Source estimation of MeO- and OH-PBDEs in freshwater fish were discussed. Considering that up to date no freshwater sources for MeO- or OH-PBDEs have been reported, concentrations found should be mainly related to bioaccumulation from anthropogenic sources, although other sources could not be dismissed.     

Reproductive performance in East Greenland polar bears (Ursus maritimus) may be affected by organohalogen contaminants as shown by physiologically-based pharmacokinetic (PBPK) modelling

Polar bears (Ursus maritimus) feed mainly on ringed seal (Phoca hispida) and consume large quantities of blubber and consequently have one of the highest tissue concentrations of organohalogen contaminants (OHCs) worldwide. In East Greenland, studies of OHC time trends and organ system health effects, including reproductive, were conducted during 1990–2006. However, it has been difficult to determine the nature of the effects induced by OHC exposures on wild caught polar bears using body burden data and associated changes in reproductive organs and systems. We therefore conducted a risk quotient (RQ) evaluation to more quantitatively evaluate the effect risk on reproduction (embryotoxicity and teratogenicity) based on the critical body residue (CBR) concept and using a physiologically-based pharmacokinetic (PBPK) model. We applied modelling approaches to PCBs, p,p′-DDE, dieldrin, oxychlordane, HCHs, HCB, PBDEs and PFOS in East Greenland polar bears based on known OHC pharmacokinetics and dynamics in laboratory rats (Rattus rattus). The results showed that subcutaneous adipose tissue concentrations of dieldrin (range: 79–1271 ng g⁻¹ lw) and PCBs (range: 4128–53 923 ng g⁻¹ lw) reported in bears in the year 1990 were in the range to elicit possible adverse health effects on reproduction in polar bears in East Greenland (all RQs ⩾ 1). Similar results were found for PCBs (range: 1928–17 376 ng g⁻¹ lw) and PFOS (range: 104–2840 ng g⁻¹ ww) in the year 2000 and for dieldrin (range: 43–640 ng g⁻¹ lw), PCBs (range: 3491–13 243 ng g⁻¹ lw) and PFOS (range: 1332–6160 ng g⁻¹ ww) in the year 2006. The concentrations of oxychlordane, DDTs, HCB and HCHs in polar bears resulted in RQs < 1 and thus appear less likely to be linked to reproductive effects. Furthermore, sumRQs above 1 suggested risk for OHC additive effects. Thus, previous suggestions of possible adverse health effects in polar bears correlated to OHC exposure are supported by the present study. This study also indicates that PBPK models may be a supportive tool in the evaluation of possible OHC-mediated health effects for Arctic wildlife.