Chlorobiphenyls Research Articles

By-Side Impurities in Chloronaphthalene Mixtures of the Halowax Series: All 209 Chlorobiphenyls

202 congeners of chlorobiphenyl (CB) with 109 single-resolved compounds and 93 co-eluting, which represented from mono- to deca-CB were quantified as by-side impurities in all seven and of various type the technical chloronaphthalene (CN) formulations of the Halowax series. IUPAC No. 104, 145, 159, 169, 184, 186, and 188 were undetected (<0.05–<0.7 ng/g). The total CBs content of the Halowax formulations ranged between 220 and 640,000 ng/g, and lower chlorinated Halowaxes 1031 (27% Cl) and 1000 (35% Cl) were two to three orders of magnitude more contaminated with CBs than higher chlorinated Halowax 1001, 1099, 1013, 1014, and 1051 (49–70% Cl). The profile of CB homologue groups of the Halowaxes changed and followed somehow a degree of chlorination of the parent CN mixture. For Halowax 1031 and 1000, a decreasing trend in proportion from mono- to deca-CB was evident, while for Halowax 1001, 1099, 1013, 1014, and 1051 the relative proportions between the CB homologue groups varied somehow. Evidently content of lower chlorinated mono- and di-CBs highly decreased and steadily increased tri- to octa-CBs and they become dominating homologues in Halowax formulations in parallel with an increase of the content of higher molecular weight CN constituents, respectively. Among planar non- and mono-ortho CBs, total concentrations in Halowax formulations were detected in the range of 2.0–2600 ng/g, and only 3,3′,4,4′,5,5′-HxCB (no. 169) was undetected (<0.05 ng/g). Detection of by-side CBs in technical Halowaxes demonstrate clearly that those formulations apart from a massive introduction of dioxin-like CNs become in the past also an early source of environmental pollution with CBs, which proceeded for around 20–30 years use of original CB formulations.

The inhibition of LPS-induced splenocyte proliferation by ortho-substituted and microbially dechlorinated polychlorinated biphenyls is associated with a decreased expression of cyclin D2.

Immunological effects of polychlorinated biphenyls (PCBs) have been demonstrated in our laboratories with the peferential inhibition of lipopolysaccharide (LPS)-induced splenocyte proliferation by ortho-substituted PCB congeners. An investigation of the mechanism behind this immunotoxicity revealed an interruption in the progression of murine lymphocytes from G0/G1 into S phase by Aroclor 1242 and the di-ortho-substituted congener, 2,2'-chlorobiphenyl (CB), whereas, a non-ortho-substituted congener, 4,4'-CB, did not affect cell cycle progression. This interruption of cell cycle progression by 2,2'-CB and Aroclor 1242 was associated with a decreased expression of the cell cycle regulatory protein, cyclin D2, while expression was not affected by exposure to the non-ortho-substituted 4,4'-CB. These results suggest the preferential inhibition of LPS-induced splenocyte proliferation by ortho-substituted congeners is a result of a decreased expression of cyclin D2, which leads to an interruption in cell cycle progression. In addition, PCB mixtures with an increased percentage of chlorines in the ortho position following an environmentally occurring degradation process inhibited LPS-induced proliferation, interrupted cell cycle progression, and decreased cyclin D2 expression. This study provides evidence for a mechanism of action of the immunological effects of ortho-substituted individual congeners as well as environmentally relevant mixtures enriched in congeners with this substitution pattern.

Bioconcentration and redeposition of polychlorinated biphenyls by zebra mussels ( Dreissena polymorpha) in the Hudson River

The potential impact of zebra mussel infestation on the dynamics of polychlorinated biphenyls (PCBs) in the Hudson River was determined by investigating the biodeposition and bioconcentration of PCBs, using algal food contaminated with 2,5,2′- and 2,4,2′,4′-chlorobiphenyls (CBPs) in the laboratory. Approximately 46–90% of the total food was ingested depending on the supply rate. The highest proportion of ingested congeners was found in biodeposits (64±11% for 2,5,2′-CBP, and 52±6% for 2,4,2′,4′-CBP), followed by tissues (17±3% for 2,5,2′-CBP, and 23±5% for 2,4,2′,4′-CBP), and the lowest in shells. The clearance rate decreased with increasing food concentration, but increased with dilution rate. On the other hand, ingestion rate (IR) increased with food concentration and dilution rate. IR also increased with food supply rate (food concentration×dilution rate) following the same linear function whether the supply rate was varied through food concentration or dilution rate. Therefore, the dilution rate- or food concentration-dependent variation in IR was due to the change in the food supply rate. IR was independent of the kind of PCB congeners. The trend of bioaccumulation in mussel tissues from food ingestion was similar to that of IR; bioaccumulation increased linearly with food supply rate, whether the supply rate was varied through the dilution rate or the food concentration. The bioaccumulation of 2,4,2′,4′-CBP was significantly higher than that of 2,5,2′-CBP ( p<0.05). The bioaccumulation was linearly related to the IR or to the total amount of food ingested. Assimilation efficiency, PCB incorporated in the tissue per total ingested PCB, was higher for 2,4,2′,4′-CBP than for 2,5,2′-CBP ( p<0.05). The congener concentration in biodeposits increased with food supply rate. However, the concentration of 2,5,2′-CBP was significantly greater than that of 2,4,2′,4′-CBP in a mirror image of bioaccumulation. These results indicate that zebra mussels may significantly alter PCB dynamics in the Hudson River through redeposition from the water column and through bioconcentration.

Isomer-specific analysis of chlorinated biphenyls, naphthalenes and dibenzofurans in Delor: polychlorinated biphenyl preparations from the former Czechoslovakia

Technical polychlorinated biphenyl (PCB) preparations—Delors® 103, 104, 105 and 106—produced in the former Czechoslovakia were analyzed for their chlorobiphenyl (CB), chloronaphthalene (PCN) and chlorinated dibenzofuran (PCDF) composition and content using high resolution gas chromatography-mass spectrometry techniques. The congener patterns of Delors 103, 104, 105 and 106 resembled Aroclors 1242, 1248, 1254 and 1260. Delors contained PCNs and PCDFs, as impurities, at microgram per gram concentrations. Concentrations of PCNs and PCDFs in Delors were greater than those found in the corresponding Aroclors. The potential for the emissions of PCNs and PCDFs from Delor was estimated to be 3680 and 860 kg, respectively. Non- and mono-ortho PCBs were the major contributors to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents in Delor mixtures.

Rainbow trout (Oncorhynchus mykiss) can eliminate chiral organochlorine compounds enantioselectively.

Dietary accumulation of four chiral organochlorine compounds--alpha-hexachlorocyclohexane (alpha-HCH), trans-chlordane, and chlorobiphenyls (CBs) 95 and 136-by immature rainbow trout (Oncorhynchus mykiss) was studied to determine if fish can accumulate and eliminate these compounds enantioselectively. Fish rapidly accumulated all four compounds from food spiked at micrograms per gram concentrations during a 40-d feeding period. Depuration half-lives were from 13 d for (+/-)-alpha-HCH to 375 d for (+/-)-CB 136. Fish preferentially eliminated (-)-trans-chlordane and (+)-CB 136, with significant nonracemic residues observed after 20 d. These results are consistent with field measurements of these compounds in fish as well as known metabolic pathways. Enantiomeric fractions (EFs) for these two compounds changed significantly over the course of the experiment, suggesting that trout were enantioselectively biotransforming the compounds during the 238-d depuration phase. CB 95 and alpha-HCH residues were racemic throughout the experiment. High biomagnification factors for CB 95 suggest that it was not metabolized. Minimum values for metabolic elimination rates calculated from EF suggest that at least 58% of the trans-chlordane depuration rate can be attributed to metabolism, and all of the CB 136 depuration rate can be attributed to it. This study highlights the potential of chiral analysis as a tracer of in vivo biotransformation processes of xenobiotic compounds.

Tracing the source of 3,3 ′-dichlorobiphenyl found in samples collected in and around Halifax Harbour

3,3 ′-dichlorobiphenyl (IUPAC No. 11), a chlorobiphenyl (CB) that is not generally analysed in environmental studies of CBs, is found, sometimes at high concentrations, in water, suspended particulate material, biota and sediments from Halifax Harbour, NS, Canada. The results presented demonstrate the need for investigations of non-Aroclor CBs like CB 11. Not only can they have rather elevated environmental concentrations like those reported here for CB 11, but they also can be members of the more toxic non- ortho class of CBs and thus important from a toxicity standpoint. The focus of this paper was to investigate the possible sources of CB 11, a trace constituent of commercial mixtures, but dominant in various environmental compartments of Halifax Harbour.

Hepatic enzyme induction and acute endocrine effects of 2,2',3,3',4,6'-hexachlorobiphenyl and 2,2',3,4',5',6-hexachlorobiphenyl in prepubertal female rats.

Polychlorinated biphenyls (PCBs) with the liable 2,3,6-substitution are important components of certain commercial mixtures and frequently detected in biota, but little is known about their enzyme induction abilities and possible endocrine-disrupting effects. CB 132 (2,2',3,3',4,6'-hexachlorophenyl) and CB 149 (2,2'3,4',5',6-hexachlorophenyl) were investigated in weanling female rats dosed intraperitoneally on days 21 and 22 and killed on day 24 of age. Uterotropic response, serum thyroid hormone, and hepatic enzyme induction were examined in prepubertal female rats treated with these two environmentally relevant 2,3,6-substituted chlorobiphenyl (CB) congeners from 8 mg/kg to 96 mg/kg. The readily metabolized CB 132 did not cause any significant increase in all endpoints measured in the present study. On the other hand, CB 149 was a weak PROD and BROD inducer and a modest depleter of serum thyroxine in prepubertal female rats. The finding of thyroid hormone disruption by CB 149 may lead to biologically significant neurobehavioral and neurochemical changes in developing animals via milk lactation.

Trends in organochlorine residue concentrations and burdens in grey seals ( Halichoerus grypus) from Sable Is., NS, Canada, between 1974 and 1994

In blubber from maternal grey seals ( Halichoerus grypus) from Sable Is., NS, ΣDDT ( p,p′-DDE and p,p′-DDT) concentrations declined from 12 μg/g lipid in 1974 to 0.5 μg/g in 1994. Pup blubber ΣDDT concentrations were about 60% of those of their mothers, and declined at similar rates. In maternal seals, p,p′-DDE increased from 56% ΣDDT in 1974 to 89% in 1994. Polychlorinated biphenyl concentrations did not change between 1976 and 1988, but then declined; the relative proportion of chlorobiphenyl (CB) 101 increased, and those of CBs 170 and 187 decreased between 1985 and 1991. Concentrations of α-hexachlorocyclohexane and trans-nonachlor declined after 1988, and of oxychlordane after 1992; concentrations of hexachlorobenzene were constant between 1984 and 1994.

Evaluation of dialysis as a technique for the removal of lipids prior to the GC determination of ortho- and non-ortho-chlorobiphenyls, using 14C-labelled congeners.

Dialysis was evaluated as a non-destructive clean-up technique to isolate chlorobiphenyls (CBs) from fish-oil prior to further analysis. 14C-CBs were used to study the transfer processes of the CBs across polyethylene membranes. Single step processes using equilibrium dialysis were compared to a dynamic method of refluxing solvent. The dynamic method reduced the duration of the separation to 8 h. The transfer of CBs and the lipids was dependent on temperature and nature of the analyte with smaller molecules being dialysed substantially faster than larger molecules. An optimised dynamic method was used to compare the dialytic clean-up with a traditional method using sulfuric acid-impregnated silica for the determination of CBs in a laboratory reference material. Labelled recovery standards for each individual congener are recommended in combination with dialysis as a method for clean-up.

Importance of passive diffusion in the uptake of polychlorinated biphenyls by phagotrophic protozoa.

Unicellular protozoan grazers represent a size class of organisms where a transition in the mechanism of chlorobiphenyl (CB) introduction, from diffusion through surface membranes to ingestion of contaminated prey, could occur. This study compares the relative importance of these two processes in the overall uptake of polychlorinated biphenyls by protists. Uptake rates and steady-state concentrations were compared in laboratory cultures of grazing and nongrazing protozoa. These experiments were conducted with a 10-microm marine scuticociliate (Uronema sp.), bacterial prey (Halomonas halodurans), and a suite of 21 CB congeners spanning a range of aqueous solubilities. The dominant pathway of CB uptake by both grazing and nongrazing protozoa was diffusion. Organic-carbon-normalized CB concentrations (in the protozoan cell) were equivalent in grazing and nongrazing protozoa for all congeners studied. Rate constants for uptake into and loss from the protozoan cell were independently determined by using [3,3',4, 4'-(14)C]tetrachlorobiphenyl (IUPAC no. 77), 0.38 +/- 0.03 min(-1) and (1.1 +/- 0.1) x 10(-5) (g of organic carbon)(-1) min(-1), respectively. Magnitudes of the uptake and loss processes were calculated and compared by using a numerical model. The model result was consistent with data from the bioaccumulation experiment and supported the hypothesis that diffusive uptake is faster than ingestive uptake in phagotrophic unicellular protozoa.

Investigating potential associations between chronic exposure to polychlorinated biphenyls and infectious disease mortality in harbour porpoises from England and Wales

Bioaccumulation of immunosuppressive organochlorines like polychlorinated biphenyls (PCBs) may pose a threat to the health and viability of cetacean populations. To investigate possible associations between chronic exposure to PCBs and infectious disease mortality in harbour porpoises Phocoena phocoena in UK waters, blubber concentrations of 25 individual chlorobiphenyl (CB) congeners in 34 healthy harbour porpoises that died due to physical trauma (mainly by-catch) were compared with CB concentrations in 33 animals that died due to infectious disease. The infectious disease group had significantly greater total 25 CBs (Σ25CBs) concentrations than the physical trauma group ( P<0.001). The mean Σ25CBs concentration in animals that died due to physical trauma was 13.6 mg kg −1 extractable lipid whereas the mean concentration in the infectious disease group was 31.1 mg kg −1 extractable lipid. The relationship between higher Σ25CBs and the infectious disease group was not confounded by age, sex, nutritional status, season, location or year of stranding. In addition, adult females had significantly lower Σ25CBs levels than adult males ( P<0.05) due to maternal transfer of CBs to offspring. These findings are consistent with the hypothesis that chronic PCB exposure predisposes harbour porpoises in UK waters to infectious disease mortality, although further research is required to test these associations more robustly.

Analyses of tissues of eight marine species from Atlantic and Pacific coasts for dioxin-like chlorobiphenyls (CBs) and total CBs.

Eight commercially and recreationally important marine species were collected in 1993 and 1994 from several Atlantic and Pacific coastal regions of the contiguous United States. Approximately 700 edible tissue samples (e.g., whole body of mussel, crustacean muscle and hepatopancreas, and fish muscle) were analyzed for dioxin-like chlorobiphenyls (CBs) and other selected CB congeners using a rapid high-performance liquid chromatography photodiode array detection method (HPLC/PDA). Total CBs and toxic equivalents (TEQs) of dioxin-like CBs were also determined. The most abundant congeners measured in these tissues were the moderately chlorinated CBs (e.g., CB 138, 153), with mean concentrations ranging from below the limits of detection (approximately 0.2 ng/g) to 1,500 ng/g, wet weight. Certain dioxin-like CBs (e.g., CBs 77, 105, 118, 126) were also found in several of these samples (mean concentrations ranging from below the limits of detection [approximately 0.4 ng/g] to 680 ng/g). Similar to previous studies, the majority of seafood tissues contained total CB concentrations that were below the U.S. Food and Drug Administration's (FDA) tolerance limit for CBs of 2,000 ng/g, wet weight (2.0 ppm). Furthermore, the majority of samples that contained CB levels below the FDA CB tolerance limit also had CB TEQs that were lower than the FDA's advisory level for TCDD (25 ppt or 25 pg/g, wet weight) in fish from the Great Lakes, which is used in evaluating CB TEQs. Several crustacean hepatopancreas samples collected from certain Atlantic and Pacific urban sites (e.g., Dungeness crab from Elliott Bay in Puget Sound, WA, American lobster from Deer Island in Boston Harbor, MA), however, did contain total CB and CB TEQs that exceeded the FDA CB tolerance and TCDD advisory limits. Mono-ortho- (e.g., CBs 118, 105) and non-ortho-substituted congeners (e.g., CBs 77 and 126) were the largest contributors to the CB TEQs of the hepatopancreas samples that exceeded the action limit.http://link.springer-ny. com/link/service/journals/00244/bibs/37n2p205.html

Chlorobiphenyls in suspension and sediment of the southern Baltic Sea: a mass balance calculation since the onset of PCB-production

The effect of the supply of chlorinated biphenyls by the river Oder into some adjacent areas of Baltic Sea was studied in nine sediment cores and in 10 suspended matter samples. Congener-specific analysis was carried out on 28 individual chlorobiphenyls (CBs). ∑CB concentrations in suspension ranged from 2.4 pg dm -3 in the southern Bornholm Basin to 986 pg dm -3 in the Achterwasser. ∑CB contents in surface sediment decreased with increasing distance from the river mouth. Highest contents were found in the Oderhaff (18 ng g -1 dw) decreasing to 2 ng g -1 dw in the Bornholm Basin. The ∑CB contents generally decreased more or less regularly with increasing depth. The compositions of the CB mixtures in surficial sediment and suspension samples were rather similar, suggesting a common source. Compositions of the CB mixtures in the sediment cores showed distinct differences. These may reflect variations in source strength over time. Mass balance considerations on the basis of the 28 CBs resulted in an estimation of a total storage of approximate 733±158 kg ∑CBs in the Oderhaff, Achterwasser, Greifswalder Bodden, Oder Rinne, Arkona Basin and Bornholm Basin in the past 65 years, covering the time period since CBs were first produced. Based on river data about 500 kg of ∑CBs were supplied during this time by river Oder, that may thus be the major source of these compounds for the southern Baltic Sea.

Concentrations and patterns of organochlorine contaminants in marine turtles from Mediterranean and Atlantic waters

Concentrations of individual chlorobiphenyls (CBs) and organochlorine pesticides (OCPs) in marine turtle tissues collected from the Mediterranean (Cyprus, Greece) and European Atlantic waters (Scotland) between 1994 and 1996 are described. ΣCB concentrations were highest in adipose tissue and ranged from 775 to 893, 39 to 261 and 47 to 178 μg/kg wet wt in loggerhead ( Caretta carretta), green ( Chelonia mydas) and leatherback ( Dermochelys coriacea) turtles, respectively. Omnivorous loggerhead turtles had the highest organochlorine contaminant (OC) concentrations in all tissues sampled. It is thought that dietary preferences were likely to be the main differentiating factor among species. Decreasing lipid contaminant burdens with turtle size were observed in green turtles, most likely attributable to a change in diet with age. Principal component analysis of data from loggerhead and green turtles indicated that there were also pattern differences between species, confirming bioaccumulation differences.

Degradation of anaerobic reductive dechlorination products of Aroclor 1242 by four aerobic bacteria.

We studied the aerobic degradation of eight PCB congeners which comprise from 70 to 85% of the anaerobic dechlorination products from Aroclor 1242, including 2-, 4-, 2,4-, 2,6-, 2,2'-, 2,4'-, 2,2', 4-, and 2,4,4'-chlorobiphenyl (CB), and the biodegradation of their mixtures designed to simulate anaerobic dechlorination profiles M and C. Strains Comamonas testosteroni VP44 and Rhodococcus erythreus NY05 preferentially oxidized a para-substituted ring, while Rhodococcus sp. RHA1, similar to well known strain Burkholderia sp. LB400, preferably attacked an ortho-chlorinated ring. Strains with ortho-directed attack extensively degraded 2,4'- and 2,4,4'-CB into 4-chlorobenzoate, while bacteria with para-directed attack transformed these congeners mostly into potentially problematic meta-cleavage products. The strains that preferentially oxidized an ortho-substituted ring readily degraded seven of the eight congeners supplied individually; only 2,6-CB was poorly degraded. Degradation of 2,2'- and 2,4,4'-CB was reduced when present in mixtures M and C. Higher efficiencies of degradation of the individual congeners and defined PCB mixtures M and C and greater production of chlorobenzoates were observed with bacteria that preferentially attack an ortho-substituted ring. PCB congeners 2,4'-, 2,2',4-, and 2,4,4'-CB can be used to easily identify bacteria with ortho-directed attack which are advantageous for use in the aerobic stage of the two-phase (anaerobic/aerobic) PCB bioremediation scheme.

Studies of bioaccumulation and biotransformation of PCBs in mustelids based on concentration and congener patterns in predators and preys.

Bioaccumulation of non-, mono-, and di-ortho-substituted chlorobiphenyls (CBs) was investigated in four species of mustelids (weasel, stoat, polecat, and otter) and their preys, from a restricted area in the northern part of The Netherlands. Diets of these mustelids ranged from terrestrial (weasel, stoat, and polecat) to aquatic (otter). Diet-specific biomagnification factors (BMFs), CB in diet relative to CB in mustelids, were calculated for the sum of 28 congeners (SigmaCB), for the sum of the toxic equivalent concentration (SigmaTEQ) and on an individual congener basis. Biotransformation was studied in relation to structural CB properties (vicinal H-atom substitution). In addition, the methylsulphonyl CB-metabolites were determined. The concentration of SigmaCB on lipid weight basis increased in the order weasel < stoat < polecat < otter. On the basis of SigmaTEQ, the order changed to weasel < polecat < stoat < otter. Most of the differences in BMFs between the CBs could be explained by the vicinal H-atom structure-activity rules. For all mustelids, the lowest BMFs were found for congeners with vicinal H-atoms in the meta, para position. Indications were found that all mustelid species can metabolize these congeners. For some of the CBs, their methylsulphonyl-CB metabolites were determined and found to be present in concentrations up to 350-fold higher than those of the parent compounds. In addition, the non-ortho CBs 126 and 169 are selectively retained in the liver of weasel, stoat, and otter. These CBs had the highest BMFs of all congeners. However, rather surprisingly, in polecat the highest BMFs were found for di-ortho-substituted CBs. This animal was able to metabolize all congeners with vicinal H-atoms in the ortho and meta position (non- and mono-ortho CBs). The information concerning the differences in bioaccumulation of CBs for closely related mustelid species increased the understanding of reported differences in PCB toxicity between mink and ferrets, and suggest that weasel, stoat, and otter are at least as sensitive to CBs as are mink, while polecats are less sensitive. As otter is exposed to much higher concentrations of CBs trough their diet than weasel and stoat, the toxic threat of CBs will be the greatest for this animal.

Chlorobiphenyls (PCB) and PAHs in water masses of the northern North Atlantic

Concentrations of 23 individual chlorobiphenyls (CBs) and 6 polyaromatic hydrocarbons (PAHs) were determined in different water masses of the North Atlantic Ocean around Iceland. The study was carried out in the framework of the second Intergovernmental Oceanographic Commission (IOC) baseline studies of contaminants in the North Atlantic Ocean, involving trace organics and trace elements. Concentrations of individual CBs were extremely low. In solution, they varied between <2 and 126 fg dm−3 and in suspension between <2 and 1400 fg dm−3. The values for their sum (∑CB) were between 10 and 1048 in solution, and 286–11 241 fg dm−3 in suspension. ∑PAHs were present in the <5–65 pg dm−3 range, p,p′-DDE and hexachlorobenzene were <2 fg dm−3. The concentrations of CBs and PAHs decreased from the surface towards the bottom at each station. The lowest concentrations were found in Norwegian Sea Deep Water (∑CB 10 fg dm−3), concurrent with the lowest halocarbon concentrations found during the cruise. Values in near-surface waters were considerably lower than those determined at mid-latitudes of the North Atlantic. These findings reflect the mixing of water bodies with higher CB concentrations from the central North Atlantic with less contaminated waters from the Arctic Ocean. Concentrations in suspension exceeded those in solution in most samples, as a result of the relatively high suspended matter concentrations in the waters around Iceland. Particulate CB and PAH concentrations were positively correlated with particulate organic carbon concentrations. This suggests that suspended organic material is a carrier for these relatively apolar organic compounds in the water column. The data do not support the co-distillation concept suggested in the literature.

Multivariate analysis applied to the study of the distribution of chlorobiphenyls (CBs), including the non-ortho-CBs, in fish and sea mammals

Twenty-one individual chlorobiphenyls (CBs), including the most toxic non-ortho-CBs, were determined in 52 samples of sea mammals, harbour porpoise (Phoceana phoceana), dabs (Limanda limanda), seals (Phoca vitulina) and dolphins (Tursiops truncatus). The toxic non-ortho-CBs and mono-ortho-CBs were isolated from the di- and tri-ortho-CBs using a pyrenylsilica HPLC column prior to the final determination by GC with electron-capture detection. The distribution of the CBs in the different species were studied by principal component analysis. Separations of males and females, young and adult individuals and the different species of sea mammals were obtained based on the degree of accumulation of CBs.

Concentration-dependent changes of PCB patterns in fish-eating mammals: structural evidence for induction of cytochrome P450.

Data sets on CB concentrations in fish-eating mammals from five laboratories were combined to test and refine a pharmacokinetic model. Clear differences in PCB patterns were observed between species. The ability to metabolize chlorobiphenyl (CB) congeners with vicinal H-atoms only in the ortho- and meta-positions and with one ortho-chlorine substituent generally increased in the order otter < cetaceans (harbor porpoise, common dolphin) < phocid seals (harbor and grey seal), but the metabolism of congeners with vicinal H-atoms in the meta- and para-positions and with two ortho-chlorines increased in the order cetaceans < seals < otter. Both categories of congeners are probably metabolized by different families of cytochrome P450 (1A and 2B) of which levels apparently differed between the cetaceans, the pinnipeds, and the otter. Within-species CB patterns differed in a concentration-dependent manner. The induction of cytochrome P450 enzymes offers the most likely explanation for this phenomenon, but starvation could have a similar effect on occasion.

Infection, haematology and biochemistry in grey seal pups exposed to chlorinated biphenyls

Grey seal ( Halichoerus grypus) pups can receive substantial doses of organochlorine contaminants during lactation. This exposure may cause immunosuppression. We studied the effect of exposure to individual chlorobiphenyl (CB) congeners on grey seal pups at the Isle of May in the Firth of Forth, Scotland, by monitoring the prevalence of non-specific infection in pups, and by measuring perturbations in various haematological and biochemical blood parameters. There was no relationship between the prevalence of infection in pups, as a sign of immunosuppression, and the cumulative lactational dose of CB congeners. There was also no relationship between age at diagnosis of infection and CB dose, thus pups receiving relatively higher doses of contaminants early in life were no more likely to succumb to infection than those receiving lower doses. There was also no relationship between age-related changes in haematological and biochemical blood parameters and exposure to CB contaminants. Although pups which became infected with non-specific pathogens had received higher cumulative doses of CB on a toxicity equivalence basis than those which did not, this effect disappeared when results were corrected for the effect of pup age.