Comparative toxicities of the polychlorinated dibenzofuran (PCDF) and biphenyl (PCB) mixtures which persist in Yusho victims

The toxic Yusho oil contained a mixture of polychlorinated biphenyls (PCBs) which were contaminated by other halogenated aromatics including the highly toxic polychlorinated dibenzofurans (PCDFs). It has been reported that the PCBs and PCDFs which persist in the liver of victims still suffering from Yusho poisoning include the following compounds; 2,3′,4,4′,5-penta-,2,2′,4,4′,5,5′-,2,2′,3′,4,4′,5- and 2,3,3′,4,4′,5-hexa, 2,2′,3,4,4′,5,5′- and 2,2′,3,3′,4,4′,5-heptachlorobiphenyls and the 2,3,7,8-tetra-, 1,2,4,7,8-, 1,2,3,7,8- and 2,3,4,7,8-penta- and 1,2,3,4,7,8-hexachlorodibenzofurans. All of these PCBs and PCDFs have been synthesized and reconstituted to approximate their composition in human liver. A comparison of the dose-response effects of the reconstituted PCB and PCDF mixtures in causing weight loss, thymic atrophy and the induction of cytochrome P-448-dependent monooxygenases indicated that the PCDF mixture was at least 700 times more active than the PCBs. Since the ratio of PCBs/PCDFs persisting in Yusho patients' blood and liver was less than 600:1 and 5:1 respectively, the results suggest that the PCDFs are the major etiologic agent in Yusho poisoning.     

Accumulation properties of polychlorinated biphenyl congeners in Yusho patients and prediction of their cytochrome P450-dependent metabolism by in silico analysis

In what has become known as the Yusho incident, thousands of people in western Japan were poisoned by the accidental ingestion of rice bran oil contaminated with polychlorinated biphenyls (PCBs) and various dioxins and dioxin-like compounds. In this study, we investigated the accumulation patterns of 69 PCB congeners in the blood of Yusho patients in comparison with those of non-exposed controls. The blood samples were collected at medical check-ups in 2004 and 2005. To compare the patterns of PCB congeners, we calculated the concentration ratio of each congener relative to the 2,2′,4,4′,5,5′-hexaCB (CB153) concentration. The concentration ratios of tetra- and penta-chlorinated congeners in the blood of Yusho patients were significantly lower than those of controls. To examine the cytochrome P450 (CYP)-dependent metabolic potential of the 2,3′,4,4′5-pentaCB (CB118), CB153, and 2,3,3′,4,4′5-hexaCB (CB156) congeners, we conducted PCB-CYP (CYP1A1, CYP1A2, CYP2A6, and CYP2B6) docking simulation by in silico analysis. The docking models showed that human CYP1A1, CYP2A6, and CYP2B6 isozymes have the potential to metabolize CB118 and CB153. On the other hand, it was inferred that CB156 is difficult to be metabolized by these four CYP isozymes. These results indicate that CYP1 and CYP2 isozymes may be involved in the characteristic accumulation patterns of PCB congeners in the blood of Yusho patients.     

Highly toxic coplanar PCBs: occurrence, source, persistency and toxic implications to wildlife and humans

Isomer-specific determinations of PCB congeners in a wide variety of animal species such as fish, marine mammals (whale, dolphin and porpoise) and terrestrial mammals (dog, cat and human) revealed the environmental occurrence of highly toxic coplanar 3,3',4,4'-tetrachlorobiphenyl (T(4)CB), 3,3',4,4',5-pentachlorobiphenyl (P(5)CB) and 3,3',4,4',5,5'-hexachlorobiphenyl (H(6)CB) within a range of few pg g(-1) to several ten ng g(-1) in fat tissues (except fish) on a wet weight basis. Detection of these toxic residues in wild specimens collected from remote areas such as the North Pacific suggests the already widespread distribution of coplanar PCBs as in the case of general PCB pollution. The clear positive correlations between concentrations of total PCBs and each of the three coplanar PCBs obtained in all mammals analysed suggest that the sources of coplanar PCB contamination to the environment are mainly commercial PCB preparations. Comparison of the composition of three toxic coplanar PCBs in commercial PCB mixtures and in the various animals indicates the relative metabolisability of these congeners as follows: 3,3',4,4'-T4CB>3,3',4,4',5-P5CB>3,3',4,4',5,5'-H6CB. Moreover, marine mammals seem to have lower potency to metabolise the coplanar PCBs in comparison with terrestrial mammals. In human adipose tissues, the concentrations of coplanar PCBs were found to be much higher than 2,3,7,8-tetrachlorodibenzo-p-dioxin (T(4)CDD), 2,3,4,7,8-pentachlorodibenzofuran (P(5)CDF) and other toxic congeners. 'T(4)CDD-equivalent' analysis based on the enzyme induction potencies and the residues of these toxic chemicals indicates that 3,3',4,4',5-P(5)CB may impose a greater toxic threat than dioxins and furans to the humans and probably to wildlife also.     

Persistency of highly toxic coplanar PCBs in aquatic ecosystems: uptake and release kinetics of coplanar PCBs in green-lipped mussels (Perna viridis Linnaeus)

The bioaccumulation potential of three highly toxic coplanar PCB isomers [3,3',4,4'-tetrachlorobiphenyl (T(4)CB); 3,3',4,4',5-pentachlorobiphenyl (P(5)CB); and 3,3',4,4',5,5'-hexachlorobiphenyl (H(6)CB)] was investigated using green-lipped mussels (Perna viridis Linnaeus) as a bioindicator, through a transplantation experiment at two locations in Hong Kong waters. By contrast to the relatively rapid uptake and release of many other PCB isomers, the non-ortho chlorine substituted coplanar PCB congeners exhibited slow uptake and clearance. The kinetic parameters of coplanar PCBs based on lipid weight-related data, and the degree of bioaccumulation based on the proportion of coplanar PCBs in total PCBs in mussels, clearly indicate that coplanar PCBs are highly bioaccumulative in lower organisms. On the assumption that mussels are unlikely to be particularly unusual with respect to their bioaccumulation of coplanar PCBs, it appears most likely that these highly toxic and persistent PCB congeners are concentrated by all aquatic organisms, and may reach higher consumers (including humans) in quantities of toxicological concern.     

Polychlorinated biphenyls (PCBs) in sediments in Hong Kong: a congener-specific approach to the study of coplanar PCBs in aquatic ecosystems

Patterns of contamination by polychlorinated biphenyls (PCBs) were investigated in fourteen samples of coastal sediments from Hong Kong. Congener-specific analyses revealed nine sediment samples from Junk Bay to contain PCBs at concentrations ranging from 31 to 2200 ng g(-1) dry weight, concentrations generally increasing with distance north in the Bay. By contrast, five sediments from the Tolo area to the north-east of Hong Kong exhibited total PCB levels of only 6.6 to 45 ng g(-) dry weight. The patterns of relative abundance of PCB congeners in the northern Junk Bay sediments suggested the existence of ongoing source(s) of PCBs in this area; biphenyls of lower chlorination were present at high concentration in these samples. Three coplanar PCBs (3', 4, 4'-tetrachlorobiphenyl; 3,3',4,4',5-pentachlorobiphenyl; and 3,3',4,4',5,5'-hexachlorobiphenyl) were found to be present in Junk Bay sediments; these are highly toxic and are cause for concern in aquatic environments. The abundance of the three coplanar PCBs in the sediments studied was similar to that in commercial PCB mixtures, suggesting that these congeners are not enriched over other PCBs by the sediments of coastal ecosystems. It is concluded that the preferential enrichment of coplanar PCBs occurs in the biosphere, rather than in sediments.     

Accelerated photo-transformation of 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153) in water by dissolved organic matter

The ubiquitous dissolved organic matter (DOM) has an important influence on transformation of organic contaminants through the production of reactive substances, such as ^?OH, ¹O₂, and ³DOM*. The photolysis of a higher chlorinated polychlorinated biphenyl (PCB) congener (2,2′,4,4′,5,5′-hexachlorobiphenyl, PCB 153) under simulated sunlight in presence of humic acid (HA) was investigated. Degradation of PCB 153 was accelerated significantly by the addition of HA, with a rate constant of 0.0214, 0.0413, and 0.0358 h^?1 in the initial 18 h of irradiation in presence of 1, 5, and 20 mg/L HA, respectively. The main photodegradation products analyzed by gas chromatography mass spectrometry were 4-hydroxy-2,2′,4′,5,5′-pentaCB and 2,4,5-trichlorobenzoic acid. Main reactive species involved were determined by the electron spin-resonance spectroscopy, including ¹O₂ and ^?OH. Special scavengers were added to elucidate the photolysis mechanisms. By using the specific scavengers, it turned out that ^?OH accounted for 29.3 % of the degradation, and the intra-DOM reactive species (¹O₂, ^?OH, and ³DOM*) accounted for 59.6 % of the degradation. Photo-transformation sensitized by DOM, which involves both aqueous and intra-DOM reactions of PCBs with reactive species, may be one of the most important mechanisms for natural attenuation of PCBs.     

Contributions to ecological chemistry CXLII: Separation and identification of metabolites excreted by rats after long term oral administration of imugan-14C

Rapid conversion and high rate of excretion of the fungicide, Imugan- ¹⁴C (N-formyl-N′ - (3,4-dichlorophenyl)-2, 2, 2-trichloroacetaldehydeaminal, Fig. 1) has been observed in rats upon long term oral administration². In simulated waste composting experiments³ this fungicide is metabolized to 3,4-dichloroaniline (3,4-DCA). 3,4-DCA and 3,3′, 4,4′-tetrachloroazobenzene (3,3′, 4,4′-TCAB) have been isolated from soil treated with it⁴. Algae have been found to convert it to a ring hydroxylated monohydroxy 3,3′,4,4′-TCAB⁵. In this work, the isolation and structure elucidation of metabolites of Imugan excreted with urine and faeces of rats are reported.     

Effects of thiol antioxidants on the atropselective oxidation of 2,2′,3,3′,6,6′-hexachlorobiphenyl (PCB 136) by rat liver microsomes

Chiral polychlorinated biphenyl (PCB) congeners, such as PCB 136, are atropselectively metabolized to various hydroxylated PCB metabolites (HO-PCBs). The present study investigates the effect of two thiol antioxidants, glutathione and N-acetyl-cysteine (NAC), on profiles and chiral signatures of PCB 136 and its HO-PCB metabolites in rat liver microsomal incubations. Liver microsomes prepared from rats pretreated with phenobarbital were incubated with PCB 136 (5 μM) in the presence of the respective antioxidant (0–10 mM), and levels and chiral signatures of PCB 136 and its HO-PCB metabolites were determined. Three metabolites, 5-136 (2,2′,3,3′,6,6′-hexachlorobiphenyl-5-ol), 4-136 (2,2′,3,3′,6,6′-hexachlorobiphenyl-4-ol), and 4,5-136 (2,2′,3,3′,6,6′-hexachlorobiphenyl-4,5-diol), were detected in all incubations, with 5-136 being the major metabolite. Compared to microsomal incubations without antioxidant, levels of 4,5-136 increased with increasing antioxidant concentration, whereas levels of PCB 136 and both mono-HO-PCBs were not affected by the presence of either antioxidant. PCB 136, 4-136, and 5-136 displayed significant atropisomeric enrichment; however, the direction and extent of the atropisomeric enrichment was not altered in the presence of an antioxidant. Because 4,5-136 can either be conjugated to a sulfate or glucuronide metabolite that is readily excreted or further oxidized a potentially toxic PCB 136 quinone, the effect of both thiol antioxidants on 4,5-136 formation suggests that disruptions of glutathione homeostasis may alter the balance between both metabolic pathways and, thus, PCB 136 toxicity in vivo.     

Effects of polychlorinated biphenyls on whole animal energy mobilization and hepatic cellular respiration in rainbow trout, Oncorhynchus mykiss

The production of polychlorinated biphenyls (PCBs) was banned in 1977 but these chemicals persist in the environment and threaten aquatic organisms. PCB exposure often results in activation of the aryl hydrocarbon receptor (AhR) and increases in hepatic detoxification mechanisms. Activation of these detoxification mechanisms is believed to be associated with energetic demands that may come at the expense of other physiological processes such as growth, activity and reproduction. We tested the hypothesis that exposure to sub-lethal levels of PCBs results in increased energy demand and energy mobilization using both an in vivo and in vitro approach. Rainbow trout (Oncorhynchus mykiss) received a single intraperitoneal sub-lethal dose (50 μg kg⁻¹) of 3,3’,4,4’,5-pentachlorobiphenyl (PCB 126) and left for 10 d after which standard oxygen consumption and plasma and liver metabolites were assessed. PCB 126 exposed trout did not alter standard oxygen consumption but did increase plasma glucose concentration implying the mobilization of glucose to cope with this exposure regime. Cellular respiration was assessed in trout hepatocytes exposed to PCB 126 or PCB 77 (3,3′4,4′-tetrachlorobiphenyl) two AhR activators but with different potencies (PCB 126 ? PCB 77). Mitochondrial respiration was assessed by stimulating complex II with succinate and although no increases in respiration were associated with PCB exposure in non-stimulated cells, PCB 77 impaired mitochondrial respiration by preventing stimulation of complex II respiration and potentially masking any actual energetic costs of PCB exposure. These studies suggest that energy is mobilized upon exposure to PCBs, however, actual increases in energy demand may be overshadowed by impaired mitochondrial respiration.     

PCDDs, PCDFs, dioxin-like PCBs and indicator PCBs in soil from five selected areas in Slovakia

There is a lack of information regarding persistent organic pollutants (POPs) in soil from Slovakia. This paper reports the concentrations of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), 12 dioxin-like polychlorinated biphenyls (dl-PCBs) and 6 indicator PCBs associated with 32 soil samples collected in 2007 from areas in the vicinity up to several kilometres from four selected industrial PCDD/F sources in Slovakia and one background area.The results show that the total WHO₁₉₉₈-PCDD/F/dl-PCB-TEQ concentrations varied from 0.34 to 18.05 pg g⁻¹ dry weight (dw) and the average total TEQ concentrations in samples collected at the Šala, Košice, Krompachy and Dubová areas were 3.18, 2.64, 7.80, and 3.19 pg g⁻¹ dw respectively. The average of the total WHO₁₉₉₈-TEQ values in three soil samples representing the background Starina area was 0.66 pg g⁻¹ dw. The predominant contaminants among 2,3,7,8-substituted PCDD/Fs, dl-PCB, and indicator PCBs was OCDD, PCB 118, and PCB 153 respectively. The major contributors to the TEQ were 2,3,4,7,8-PeCDF, PCB 126, 1,2,3,7,8-PeCDD, PCB 156 and 1,2,3,4,7,8-HxCDF + 1,2,3,4,7,9-HxCDF in descending order.     

Hydrodechlorination of polychlorinated biphenyls in contaminated soil from an e-waste recycling area,using nanoscale zerovalent iron and Pd/Fe bimetallic nanoparticles

Soil pollution by polychlorinated biphenyls (PCBs) arising from the crude disposal and recycling of electronic and electrical waste (e-waste) is a serious issue, and effective remediation technologies are urgently needed. Nanoscale zerovalent iron (nZVI) and bimetallic systems have been shown to promote successfully the destruction of halogenated organic compounds. In the present study, nZVI and Pd/Fe bimetallic nanoparticles synthesized by chemical deposition were used to remove 2,2′,4,4′,5,5′-hexachlorobiphenyl from deionized water, and then applied to PCBs contaminated soil collected from an e-waste recycling area. The results indicated that the hydrodechlorination of 2,2′,4,4′,5,5′-hexachlorobiphenyl by nZVI and Pd/Fe bimetallic nanoparticles followed pseudo-first-order kinetics and Pd loading was beneficial to the hydrodechlorination process. It was also found that the removal efficiencies of PCBs from soil achieved using Pd/Fe bimetallic nanoparticles were higher than that achieved using nZVI and that PCBs degradation might be affected by the soil properties. Finally, the potential challenges of nZVI application to in situ remediation were explored.     

Polychlorinated biphenyls (PCBs) in marine fishes from China: Levels, distribution and risk assessment

Muscle tissues of large yellow croakers (Pseudosciaena crocea) and sliver pomfret (Pampus argenteus) from nine coastal cities of East China including Dalian, Tianjin, Qingdao, Shanghai, Zhoushan, Wenzhou, Fuzhou, Quanzhou and Xiamen were analyzed for polychlorinated biphenyl (PCB) concentrations. Thirty-six PCB congeners were quantified in the fishes, of which 11 congeners were dioxin-like PCBs. The total PCB concentrations of the present study were at the low end of the global range, which may be related to the smaller usage and shorter consumption history of PCBs in China. PCBs 18, 29, 52, 66, 101, 104, 138, 153, 180 and 194 were the major constituents found in the fish samples. Regression analysis showed a strong positive correlation (R² = 0.800; p < 0.001) between total dioxin-like PCBs and total PCB concentrations, and that total PCB concentrations explain 80% of the variability in total dioxin-like PCB concentrations. Among the species investigated, significantly higher concentrations of total PCBs were found in croakers than in pomfrets, which may be attributed to their different feeding and living habits. No significant difference in total PCB concentrations among the cities was observed; principal component analysis (PCA) of PCB profiles indicated that PCB pollution came from similar sources in the sampling areas and that there may be other PCB sources in Dalian and Wenzhou. The calculated carcinogenic risks (CRs) from the two species based on a low consumption group and high consumption group were all greater than 10⁻⁶, suggesting that daily exposure to dioxin-like PCBs via fish consumption results in a lifetime cancer risk of greater than one in one million. In contrast, the hazard quotients (HQs) of noncancer risks were all less than unity.     

Congener profiles of PCBs and PCDD/Fs in Yucheng victims fifteen years after exposure to toxic rice-bran oils and their implications for epidemiologic studies

In 1978-1979, a mass poisoning occurred in central Taiwan from rice-bran oil contaminated by heat-degraded PCBs was later called the Yucheng (oil disease in Chinese). Only a few studies have so far investigated the levels of specific polychlorinated biphenyl (PCB) or polychlorinated dibenzodioxin/furan (PCDD/F) congeners in the Yucheng victims. This study aimed to investigate the serum residual levels of thirty-three PCBs and seventeen 2,3,7,8-substituted PCDD/F congeners in the Yucheng victims 15 years after the exposure. Forty-one blood samples were collected from individual Yucheng victims in 1994-1995. The mean levels of total 33 PCBs and 17 PCDD/Fs were 2468 ng/g lipid (13.3 ng/g sample) and 6550 pg/g lipid (30.9 pg/g sample) respectively. The higher levels were found in PCBs #99, #138, #153, #156, #170, #179, and #180 among 33 PCB congeners, while 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, and OCDD had the higher concentrations among 17 PCDD/F congeners. The total TEQ was contributed in decreasing order by 10 PCDFs (44%), three non-ortho-PCBs (24%), six mono-ortho-PCBs (20%), and seven PCDDs (12%). The mean total PCB levels and TEQ value of the 17 PCDD/Fs in the Yucheng victims 15 years after the toxic exposure were still 9 and 46 times higher than those in the general population in Taiwan. Principle component analysis (PCA) indicated that seven PCB congeners, PCBs #99, #138, #153, #156, #170, #179, and #180, accounted for 73% of the total variances in PCBs. On the other hand, six PCDD/F congeners, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDF, and OCDD, accounted for 97% of the total variances in PCDD/Fs. In addition, PCA revealed that at least three characteristic patterns of congener profiles for PCBs were observed among the Yucheng victims. Similar trend was also observed for PCDD/Fs. These patterns may reflect distinctive exposure scenarios and/or different metabolizing capabilities among the Yucheng victims. We suggest that these patterns, in contrast to total PCB and PCDD/F levels, may be valuable for the future epidemiologic studies when linking exposure with specific health effect.     

Effect of coplanar PCB concentration on dechlorinating microbial communities and dechlorination in estuarine sediments

The effect of concentration of coplanar PCB on the dechlorinating microbial community and dechlorination were investigated in anoxic estuarine sediment collected from Er-Jen River and enriched with 10 and 50 mg L⁻¹ of 3,4,4′,5-tetrachlorobiphenyl, 3,3′,4,4′,5-pentachlorobiphenyl, and 3,3′,4,4′,5,5′-hexachlorobipheny. Dechlorination rates were similar in the cultures enriched with 10 and 50 mg L⁻¹ of 3,4,4′,5-tetrachlorobiphenyl, whereas significantly higher dechlorination rates were observed in cultures enriched with 10 mg L⁻¹ of 3,3′,4,4′,5-pentachlorobiphenyl. No dechlorination was observed in sediment slurries enriched with 3,3′,4,4′,5,5′-hexachlorobipheny. Para dechlorination occurred prior to meta dechlorination during reductive dechlorination of 3,4,4′,5-tetrachlorobiphenyl and 3,3′,4,4′,5-pentachlorobiphenyl. GC-MS and denaturing gradient gel electrophoresis (DGGE) were used to detect dechlorination products and dechlorinating microorganisms in the enriched sediment cultures during the process of degradation. Two Chloroflexi phylotypes observed in DGGE were responsible for para and meta dechlorination respectively. Phylotype Cp-1 has 98% similarity to uncultured bacterium N5-12. Phylotype Cm-1 has 99% similarity to uncultured dechlorinating bacterium m1 or SF1 belonging to the ο-17/DF-1 group of PCB-dechlorinating bacteria.     

Congener-specific analysis of non-dioxin-like polychlorinated biphenyls in blood collected from 127 elderly residents in Nakagawa Town, Fukuoka Prefecture, Japan

We conducted congener-specific analysis of non-dioxin-like polychlorinated biphenyls (non-dioxin-like PCBs) in blood collected in February 2004 from 127 elderly residents living in Nakagawa Town, Fukuoka Prefecture, Japan. The present study is one of the few studies in which 56 non-dioxin-like PCBs congeners were measured in human blood. Of the 127 elderly residents, 51 were men (mean: 68.1 years) and 76 were women (mean: 68.1 years). Among 197 non-dioxin-like PCB congeners, 56 were identified in the blood of elderly residents. The arithmetic mean total concentrations of 56 non-dioxin-like PCBs congeners in the blood of elderly men and women in Nakagawa Town were 419 (median: 378) and 363 (median: 323)ngg(-1)lipid, respectively, and the concentrations were in the range of 172-1102 and 119-1226ngg(-1)lipid, respectively, indicating that the total concentrations in elderly men are significantly higher than those in elderly women. The contamination of non-dioxin-like PCBs in the blood of elderly men and women in Fukuoka Prefecture was found to have decreased compared to past levels. The ratios of hexachlorinated biphenyls (hexaCBs) to the total concentrations of 56 non-dioxin-like PCBs congeners in the blood of elderly men and women were 44.6% and 45.6%, respectively, which was particularly high compared with those of other congeners. 2,2',4,4',5,5'-HexaCB (#153) among hexaCBs congeners, the most abundant congener in the blood of elderly men and women, contributed approximately 23.0% and 23.5% to the total concentrations of 56 non-dioxin-like PCBs congeners, respectively. Furthermore, 2,2',3,4,4',5'-hexaCB (#138), 2,3,3',4',5,6-hexaCB (#163)/2,3,3',4',5',6-hexaCB (#164), 2,2',3,4,4',5,5'-heptaCB (#180), and 2,2',3,4,4',5,6'-heptaCB (#182)/2,2',3,4',5,5',6-heptaCB (#187) also showed high ratios to the total concentrations of 56 non-dioxin-like PCBs congeners detected in the blood of elderly men and women. A statistical examination of the relationship between the total concentrations of 56 non-dioxin-like PCBs congeners in blood and the age of elderly residents who were over 60 years indicated statistically significant correlations between the total concentrations of these PCBs congeners and the age of elderly women. However, similar correlations were not observed in elderly men. The results of the present study have indicated the current levels of non-dioxin-like PCBs in the blood of elderly men and women in Fukuoka Prefecture, Japan and can be used as baseline data for those over age 60.     

Organohalogen contaminants and metabolites in cerebrospinal fluid and cerebellum gray matter in short-beaked common dolphins and Atlantic white-sided dolphins from the western North Atlantic

Concentrations of several congeners and classes of organohalogen contaminants (OHCs) and/or their metabolites, namely organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), hydroxylated-PCBs (OH-PCBs), methylsulfonyl-PCBs (MeSO₂-PCBs), polybrominated diphenyl ether (PBDE) flame retardants, and OH-PBDEs, were measured in cerebrospinal fluid (CSF) of short-beaked common dolphins (n = 2), Atlantic white-sided dolphins (n = 8), and gray seal (n = 1) from the western North Atlantic. In three Atlantic white-sided dolphins, cerebellum gray matter (GM) was also analyzed. The levels of OCs, PCBs, MeSO₂-PCBs, PBDEs, and OH-PBDEs in cerebellum GM were higher than the concentrations in CSF. 4-OH-2,3,3′,4′,5-pentachlorobiphenyl (4-OH-CB107) was the only detectable OH-PCB congener present in CSF. The sum (Σ) OH-PCBs/Σ PCB concentration ratio in CSF was approximately two to three orders of magnitude greater than the ratio in cerebellum GM for dolphins.     

Concentration levels and congener profiles of polychlorinated biphenyls, pentachlorobenzene, and hexachlorobenzene in commercial pigments

The concentration levels and congener profiles of polychlorinated biphenyls (PCBs), pentachlorobenzene (PeCBz), and hexachlorobenzene (HxCBz) were assessed in commercially available organic pigments. Among the azo-type pigments tested, PCB-11, which is synthesized from 3,3′-dichlorobendizine, and PCB-52, which is synthesized from 2,2′,5,5′-tetrachlorobendizine, were the major congeners detected. It is speculated that these were byproducts of chlorobendizine, which has a very similar structure. The total PCB concentrations in this type of pigment ranged from 0.0070 to 740 mg/kg. Among the phthalocyanine-type pigments, highly chlorinated PCBs, mainly composed of PCB-209, PeCBz, and HxCBz were detected. Their concentration levels ranged from 0.011 to 2.5 mg/kg, 0.0035 to 8.4 mg/kg, and 0.027 to 75 mg/kg, respectively. It is suggested that PeCBz and HxCBz were formed as byproducts and converted into PCBs at the time of synthesizing the phthalocyanine green. For the polycyclic-type pigments that were assessed, a distinctive PCB congener profile was detected that suggested an impact of their raw materials and the organic solvent used in the pigment synthesis. PCB pollution from PCB-11, PCB-52, and PCB-209 pigments is of particular concern; therefore, the monthly variations in atmospheric concentrations of these pollutants were measured in an urban area (Sapporo city) and an industrial area (Muroran city). The study detected a certain level of PCB-11, which is not included in PCB technical mixtures, and revealed continuing PCB pollution originating from pigments in the ambient air.     

Observation of an unusual electronically distorted semiquinone radical of PCB metabolites in the active site of prostaglandin H synthase-2

The activation of the metabolites of airborne polychlorinated biphenyls (PCBs) into highly reactive radicals is of fundamental importance. We found that human recombinant prostaglandin H synthase-2 (hPGHS-2) biotransforms dihydroxy-PCBs, such as 4-chlorobiphenyl-2′,5′-hydroquinone (4-CB-2′,5′-H₂Q), into semiquinone radicals via one-electron oxidation. Using electron paramagnetic resonance (EPR) spectroscopy, we observed the formation of the symmetric quartet spectrum (1:3:3:1 by area) of 4-chlorobiphenyl-2′,5′-semiquinone radical (4-CB-2′,5′-SQ⁻) from 4-CB-2′,5′-H₂Q. This spectrum changed to an asymmetric spectrum with time: the change can be explained as the overlap of two different semiquinone radical species. Hindered rotation of the 4-CB-2′,5′-SQ⁻ appears not to be a major factor for the change in lineshape because increasing the viscosity of the medium with glycerol produced no significant change in lineshape. Introduction of a fluorine, which increases the steric hindrance for rotation of the dihydroxy-PCB studied, also produced no significant changes. An in silico molecular docking model of 4-CB-2′,5′-H₂Q in the peroxidase site of hPGHS-2 together with ab initio quantum mechanical studies indicate that the close proximity of a negatively charged carboxylic acid in the peroxidase active site may be responsible for the observed perturbation in the spectrum. This study provides new insights into the formation of semiquinones from PCB metabolites and underscores the potential role of PGHS-2 in the metabolic activation of PCBs.     

Polychlorinated biphenyls (PCBs) and Polybrominated Diphenyl Ethers (PBDEs) in surface sediments from Monastir Bay (Tunisia,Central Mediterranean): Occurrence,distribution and seasonal variations

An assessment of PCB and PBDE contamination of surface sediments in Monastir Bay was carried out in two contrasted seasons of the year. Samples were collected from 5 sites and analyzed for the ∑₇ marker PCBs (i.e. PCBs 28, 52, 101, 118, 138, 153 and 180) and ∑₄ PBDE congeners (PBDEs 47, 99, 119 and 153) by GC/ECD. Concentrations of both PCBs and PBDEs showed seasonal variations. PCB concentrations were in the range of 3.1–9.3 ng g⁻¹ and 1.1–8.1 ng g⁻¹ in wet and dry season respectively, and sediments were considered moderately contaminated with PCBs. All PCBs analyzed were detected in surface sediments. PCB 153 and 52 congeners showed the highest relative abundance in both winter and summer. PBDE concentrations ranged from not detect to 0.1 ng g⁻¹, with only BDE-47 congener detected in sediments and only in winter. Analysis of spatial and seasonal variations indicated that PCB distribution is governed by hydrodynamics and temporal variability of inputs. While the PCB contamination appeared to be mainly land-based, PBDEs are suspected to originate from atmospheric deposition.     

Evaluation of Organochlorine Compounds (PCDDs,PCDFs, PCBs and DDTs) in Two Raptor Species Inhabiting a Mediterranean Island in Spain (8 pp)

Background Species that are at high levels of the food web have often been used as bioindicators to evaluate the presence of persistent contaminants in ecosystems. Most of these species are long-lived, so pollutant burdens may be integrated in some complex way over time. This makes them particularly sensitive to deleterious effects of Persistent Organic Pollutants (POPs). Birds have been suggested as useful organisms for monitoring pollutant levels. Traditionally such studies have been carried out with raptors such as osprey (Pandion haliaetus), peregrine falcon (Falco peregrinus), bald eagle (Haliaetus leucocephalus), etc. In this paper we present the results of a monitoring study conducted on two raptor species, osprey (Pandion haliaetus) and red kite (Milvus milvus), inhabiting a Mediterranean island (Menorca, Spain). These two species have different feeding habits; ospreys prey on fish and red kites feed on terrestrial species. This study constitutes a good opportunity to investigate if differences in feeding habits (aquatic vs. terrestrial) influences the contaminants pattern in two species inhabiting the same area. Methods The study was conducted in a non-destructive way, using only failed eggs, to avoid the damage of the population stability. Eggs were collected during the period 1994–2000. The contaminants examined were dichlorodiphenyltrichloroethanes (DDTs, including DDT and its main metabolite, DDE), polychlorinated biphenyls (PCBs), including ortho PCBs (PCBs with at least one Chlorine atom in the ortho position): #28, 52, 95, 101, 123+149, 118, 114, 153, 132+105, 138, 167, 156, 157, 180, 170, 189, 194; and non ortho PCBs (PCBs with no Chlorine atom in the ortho position): #77, 126, 169 and all the polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) with Chlorine atoms at the 2,3,7 and 8 position (2,3,7,8-substituted PCDDs and PCDFs). The analysis of organochlorine compounds was performed using a sample treatment based on a Solid Phase Matrix Dispersion procedure. Ortho PCBs and DDTs were determined by HRGC-μECD; non ortho PCBs and PCDD/Fs were determined by HRGC-HRMS. Results and Discussion The sum of the ortho PCB congeners analysed ranged from 0.94 to 15.03 μg/g wet weight (ww) for ospreys and from 1.0 to 11.2 μg/g ww for red kites. In both species, PCB congeners #153, #138 and #180 accounted about 75% to total ortho PCB concentrations. Regarding non ortho PCBs, for ospreys, concentrations ranged from 0.16 to 1.39 ng/g wet weight (ww) and for red kites from 0.12 to 0.51 ng/g ww, being congener #126 the most abundant. Concerning DDTs, concentration for ospreys ranged from 0.07 to 1.03 μg/g ww; and for red kites ranged from 0.90 to 2.10 μg/g ww, representing DDE more than 95% of the total DDTs, which proves a past use of DDT in the study area. Differences in contaminant levels between species are probably associated to feeding habits. The fish-eating species presents the highest PCB levels, whereas the terrestrial species exhibits the highest DDT levels. PCDD/Fs in ospreys were in the range 2.6–14.2 pg/g ww, while in red kites the range was slightly wider (22.2–43.2 pg/g ww), being PCDDs the major contributors in black kites. Ospreys had PCDDs similar to PCDF concentrations. PCDD/F profiles were mostly influenced by OCDD in both species. Non ortho PCBs were the major contributors to calculated Toxic Equivalent Quantity (TEQs) in both species. Conclusion In both species studied, ortho-PCBs could represent a problem of concern since 57% of the eggs exhibited levels higher than 4 μg/g ww, reported as the level that could cause reduced hatchability, embryo mortality, and deformities in birds. Recommendations and Outlook Results found in this study suggest that a more detailed study to clear up possible deleterious effects of PCBs on the bird populations studied here should be done. Section Editor: Prof. Dr. Paola Gramatica (paola.gramatica@uninsubria.it)