Partitioning of selected polychlorinated biphenyls to natural sediments

The partitioning of two polychlorinated biphenyl mixtures (Aroclor 1016 and 1242) and two tetrachlorobiphenyl isomers (2,5,3′,4′ and 2,6,2′,6′ tetrachlorobiphenyl) between water and four natural sediments was evaluated in laboratory investigations. For both Aroclor mixtures, the extent of adsorption was comparable on all four natural sediments studied. For individual isomers, partitioning was comparable with that observed for the mixtures. Both particle size distribution and total organic carbon were important factors in determining the extent of partitioning for the two isomers; but in the case of the mixtures, there was no correlation with organic content.     

DEGRADATION OF AROCLOR 1242 IN A SINGLE-STAGE COUPLED ANAEROBIC/AEROBIC BIOREACTOR

Degradation of Aroclor 1242 was studied in granular biofilm reactors with limited aeration. An aerobic biphenyl degrader, Rhodococcus sp. M5, was used to supplement a natural bacterial population present in a “bioaugmented” reactor, while the “non-bioaugmented” reactor only contained natural granular sludge. The bioaugmentation, however appeared to have no effect on the reactor performance. Aroclor measurements showed its disappearance in both reactors with only 16–19% of Aroclor recovered from the reactor biomass and effluent. Simultaneously, a chlorine balance indicated that dechlorination occurred at a specific rate of 1.43 mg PCB (g volatile suspended solids)⁻¹ d⁻¹, which was comparable to the observed rate of Aroclor disappearance. Intermediates detected in both reactors were biphenyl, benzoic acid, and mono-hydroxybiphenyls. This suggests that a near-complete mineralization of Aroclor can be achieved in a single-stage anaerobic/aerobic system due to a combination of reductive and oxidative degradation mechanisms.     

PCB sources,transformations, and contributions in recent Fox River,Wisconsin sediments determined from receptor modeling

The PCB contamination in lower Fox River sediments was investigated in order to identify possible PCB sources, contributions, and transformations, using two receptor models. Congener specific sediment PCB data from sites immediately upstream of DePere dam to Green Bay that had been gathered for the Green Bay/Fox River Mass Balance Study, were used in this analysis. The first receptor model is a self training factor analysis (FA) model with non-negative constraints that was applied to identify the PCB sources and significant congener patterns. The second is a chemical mass balance model (CMB) in which published Aroclor sources, inferred from our FA model, were used to apportion these Aroclors to each sample. The FA model indicated two significant factors, the major one being Aroclor 1242 and the other, a profile dominated by low chlorinated congeners, indicating a possible PCB alteration profile. This profile had significant contributions to samples at or around sites with total PCB concentrations higher than 50 ppm, indicating a potential anaerobic dechlorination activity. It was also deduced from the FA model that very small contributions of more highly chlorinated Aroclors may be present in the system. The results from the CMB model confirmed that the system is dominated by Aroclor 1242. Its average contribution was 95%, with small amounts of Aroclor 1254 (2%) and 1260 (1%). Two of the samples, located in the vicinity of point sources, showed high contributions of Aroclor 1016 by the CMB model. This is interpreted as an altered Aroclor profile resembling the less chlorinated Aroclor 1016. Contributions obtained form the CMB and FA models show similar patterns.     

Enhancement of PCBs biodegradation by sodium ligninsulfonate

Various mixtures of commercial PCBs (Aroclors) were rapidly biodegraded by Pseudomonas sp. 7509. The rate of biodegradation could be greatly enhanced by growing the cells in a stable PCB-ligninsulfonate emulsion. Microscopic examinations and growth studies suggested that biodegradation mainly took place at the PCB-water interface; the use of ligninsulfonate in the growth medium apparently allowed the cells to overcome the substrate limiting factor of surface area which, otherwise, might govern the subsequent rate of PCB degradation. Sodium ligninsulfonate was not degraded significantly in the PCB biodegradation process. Analyses of the culture broth, by gas chromatography, revealed that P. sp. 7509 could degrade 300 ppm of Aroclor 1254 after 18 days incubation. This degradation rate could be further enhanced by the addition of a small amount of Aroclor 1221 to the growth medium. A kinetic study, using resting cells, indicated that Aroclor 1221 was degraded much faster (980 μg h⁻¹ mg cell dry wt⁻¹) than the higher chlorinated Aroclor 1254 (43 μg h⁻¹ mg cell dry wt⁻¹). This finding was supported by manometric data which showed that regardless of the type of PCBs mixture used to grow the cells, the lower chlorinated PCBs were always oxidized faster than the higher chlorinated PCBs. The level of chlorination in a PCBs mixture therefore appears to be one of the major factors in determining its relative persistence to biodegradation.     

Organochlorine pesticide, polychlorinated biphenyl and heavy metal concentrations in wolves (Canis lupus L. 1758) from north-west Russia

The wolf Canis lupus is a major terrestrial predator in eastern Europe and, as a top carnivore, may be exposed to high concentrations of contaminants that are readily transferred through the food chain. Despite this, there are few published data on pollutant and pesticide levels in wolves. This study utilised tissues from animals legally killed by hunters for other reasons (animals were not killed for the purposes of this study) to carry out the only detailed investigation of contaminants in wolves in Europe and the first in animals from Eastern Europe. The livers of 58 wolves from the Tver and Smoliensk regions of northwest Russia (54°N 31°E to 57°N 35°E) were analysed for seven organochlorine pesticides, 24 PCB congeners, Aroclor 1254-matched summed PCBs (ΣPCBs), total mercury, cadmium and lead. Cadmium, most of the organochlorine pesticides and many PCB congeners were not detectable in any of the wolves. Hexachlorobenzene, alpha-HCH, pp′DDE, PCB congeners 118, 138, 149 and 156 and lead were detected in up to 6% of livers. Dieldrin, PCB congeners 153, 170 and 180, ΣPCBs and mercury were detected more frequently. Contaminant levels were generally low; maximum wet weight concentrations of any of the organochlorine pesticides, ΣPCBs and mercury were less than 0.1, 1 and 0.25 μg g⁻¹, respectively. PCB congeners 153, 170 and 180 accounted for 41% of the ΣPCBs. Dieldrin, ΣPCBs and mercury concentrations did not vary significantly between males and females nor between adult and juvenile (<12 months old) wolves apart from the ΣPCB concentration, which was on average five times higher in adults than juveniles. Liver residues were generally below the level normally associated with adverse effects except for lead levels which exceeded the critical 5 μg g⁻¹ dry wt. concentration in three of the 58 animals examined.     

The kinetics and reversibility of the partitioning of polychlorinated biphenyls between air and ryegrass

Lolium multiflorum (ryegrass) was contaminated with technical mixtures of polychlorinated biphenyls (PCBs) via the gas phase and the subsequent elimination of the PCBs from the vegetation was studied under field conditions. There was a pronounced decrease in the concentrations of the di- through to the pentachlorinated congeners over the 240-h elimination period. For many of the congeners the elimination was nearly complete, suggesting that the partitioning of these compounds from the gas phase into ryegrass is largely reversible. The elimination followed first order kinetics. The elimination half-lives were linearly proportional to the plant/air equilibrium partition coefficients (K(PA)) of the PCB congeners and ranged from 22 h for PCBs 8 + 5 to 87 h for PCBs 84 + 101. For the hexa- through to the octachlorinated congeners no significant decrease in the concentration of the vegetation was observed during the elimination experiment. The elimination was described well using a two-resistance model of PCB desorption which indicated that elimination of the di- and trichlorinated PCBs was limited by transport within the plant itself while elimination of the higher chlorinated congeners was limited by transport from the plant surface into the atmosphere. Furthermore, the results demonstrate that if elimination of higher chlorinated PCBs from ryegrass via biological or photochemical degradation occurs, then it is very slow.     

Organochlorines (PCBs and pesticides) in the bivalves Anadara (Senilis) senilis, Crassostrea tulipa and Perna perna from the lagoons of Ghana

The bivalves, Anadara (Senilia) senilis (n=95), Crassostrea tulipa (n=75) and Perna perna (n=30) from Ghana, were analyzed for their organochlorines (pesticides and PCBs) concentrations and the body burden. A comparison was done based on two different standard PCB mixtures (Aroclor 1254 and 1260) with the percentage individual congener contribution and that of the sample. From these comparisons, it appeared that the pattern of PCB residues in the samples was neither Aroclor 1254 nor 1260. On the other hand, there was seasonal qualitative difference in the pattern that is purely marine (in the dry season) versus terrestrial input (in the wet season). SigmaPCB was 0.10 microg/g dw or 2.2 microg/g lw (median values). There was no correlation between PCB concentration and lipid content reflecting the importance of indirect contamination of the bivalves. The pesticides, aldrin, dieldrin, endrin, lindane, DDTs, HCH, HCB, endosulfan, heptachlor epoxide and heptachlor, were detected. The most abundant pesticides were the SigmaDDT: 73 and SigmaHCH: 29 ng/g dw. DDT/DDE and hept./heptachlor epoxide ratios reflect their recent applications, while the ratio for aldrin/dieldrin suggests that the use of aldrin has been discontinued, at least on the coast of Ghana.     

Relationship between persistent organic pollutants (POPs) and ranging patterns in common bottlenose dolphins (Tursiops truncatus) from coastal Georgia, USA

Bottlenose dolphins (Tursiops truncatus) are apex predators in coastal southeastern U.S. waters; as such they are indicators of persistent organic pollutants (POPs) in coastal ecosystems. POP concentrations measured in a dolphin's blubber are influenced by a number of factors, including the animal's sex and ranging pattern in relation to POP point sources. This study examined POP concentrations measured in bottlenose dolphin blubber samples (n = 102) from the Georgia, USA coast in relation to individual ranging patterns and specifically, distance of sightings from a polychlorinated biphenyl (PCB) point source near Brunswick, Georgia. Dolphin ranging patterns were determined based upon 5 years of photo-identification data from two field sites approximately 40 km apart: (1) the Brunswick field site, which included the Turtle/Brunswick River Estuary (TBRE), and (2) the Sapelo field site, which included the Sapelo Island National Estuarine Research Reserve (SINERR). Dolphins were categorized into one of three ranging patterns from photo-identification data. Individuals with sighting histories exclusively within one of the defined field sites were considered to have either Brunswick or Sapelo ranging patterns. Individuals sighted in both field sites were classified as having a Mixed ranging pattern. Brunswick males had the highest concentrations of PCBs reported for any marine mammal. The pattern of PCB congeners was consistent with Aroclor 1268, a highly chlorinated PCB mixture associated with a Superfund site in Brunswick. PCB levels in Sapelo males were lower than in Brunswick males, but comparable to the highest levels measured in other dolphin populations along the southeastern U.S. Female dolphins had higher Aroclor 1268 proportions than males, suggesting that the highly chlorinated congeners associated with Aroclor 1268 may not be offloaded through parturition and lactation, as easily as less halogenated POPs. Individuals sighted farther from the Superfund point source had lower Aroclor 1268 proportions.     

Effects of bioaugmentation on indigenous PCB dechlorinating activity in sediment microcosms

Bioaugmentation is an attractive mechanism for reducing recalcitrant pollutants in sediments, especially if this technology could be applied in situ. To examine the potential effectiveness of a bioaugmentation strategy for PCB contamination, PCB dehalorespiring populations were inoculated into Baltimore Harbor sediment microcosms. A culture containing the two most predominant indigenous PCB dehalorespiring microorganisms and a culture containing a strain with a rare ortho dechlorination activity and a non-indigenous strain that attacks double-flanked chlorines, were inoculated into sediment microcosms amended with 2,2′,3,5,5′,6-hexachlorobiphenyl (PCB 151) and Aroclor 1260. Although we observed a similar reduction in the concentration of PCB 151 in all microcosms at day 300, a reduced lag time for dechlorination activity was observed only in the bioaugmented microcosms and the pattern of dechlorination was altered depending on the initial combination of microorganisms added. Dechlorination of Aroclor 1260 was most extensive when dehalorespiring microorganisms were added to sediment. Overall numbers of dehalorespiring microorganisms in both bioaugmented and non-bioaugmented microcosms increased 100- and 1000-fold with PCB 151 and Aroclor 1260, respectively, and they were sustained for the full 300 days of the experiments. The ability of bioaugmentation to redirect dechlorination reactions in the sediment microcosms indicates that the inoculated PCB dehalorespiring microorganisms effectively competed with the indigenous microbial populations and cooperatively enhanced or altered the specific pathways of PCB dechlorination. These observations indicate that bioaugmentation with PCB dehalorespiring microorganisms is a potentially tractable approach for in situ treatment of PCB impacted sites.     

Evaluating alternative river management options in the tidal Ouse using the QUESTS1D model

A pilot-scale field trial of phytoextraction of PCBs provides insight into the practical application of this technology, using the plant species Cucurbita pepo ssp pepo cv. Howden (pumpkin), Carex normalis (sedge), and Festuca arundinacea (tall fescue). This in situ trial took place at a historically contaminated field site, in soil contaminated with a mean concentration of 46 microg/g (range of 0.6 - 200 microg/g) total PCBs (Aroclor 1254/1260). Shoot bioaccumulation factors (where BAF(shoot)=[PCB(shoot)]/[PCB(soil)]) of up to 0.29 were achieved in sedge. Pumpkin plants produced shoot BAFs of only 0.15. However, PCB concentrations in pumpkin shoots decreased as the distance above the root increased, suggesting that higher overall pumpkin shoot BAFs might be achieved in shorter, more densely planted plants. A model for estimating the overall PCB concentration in large pumpkin shoots with minimal sampling is proposed. Examination of congener data supports the hypothesis that C. pepo ssp pepo plants exhibit a unique biological uptake mechanism that allows for the accumulation of a significant concentration of PCBs in plant shoots. Although this mechanism is not well understood, the co-eluting IUPAC congeners 93/95 and 105/127 appear to be preferentially mobilized. Presently, all three plant species exhibit potential as PCB phytoextractors, however further research is required to elucidate methods for optimizing this technology.     

The relative influence of distant and local (DEW-line) PCB sources in the Canadian Arctic

Soil PCB contamination has been delineated at 18 of 21 Distant Early Warning Line (DEW-line) stations being cleaned up by the Canadian Department of National Defence (DND). As a result, detailed surface soil delineation data has been reported for contamination exceeding 1 microg/g (dw total Aroclor), which is the remedial criteria for PCB contaminated soil under the DEW-line cleanup project. The results of this delineation work has allowed us to estimate the mass of PCB contained in surface soil at these sites and to quantify the DEW-line as a source of PCBs to both local and Arctic wide contamination. Our analysis of DEW-line cleanup delineation reports suggests that pre-cleanup surface soils (top 10 cm) with over 1 microg/g PCB constituted a source of PCBs that ranged from 0.8 to 43 kg with a mean of 18 kg. The total mass of PCB at all 18 sites was 119 kg. Previous studies have described a "halo-effect" that surrounds DEW-line sites, whereby PCB signatures in soil and plants up to 10 km from source areas were attributed to the local source. At Cambridge Bay (CAM-M), Nunavut, our inventory of PCB sources and redistribution suggests that up to 3.4 kg of PCB were exported from the site to the surrounding tundra prior to cleanup. The primary mechanism of transportation appears to be wind borne particulate. Potential vapour phase emissions of PCB from contaminated soil at DEW-line sites appears to have been negligible.     

Organochlorine levels in maternal and umbilical cord blood plasma in Arctic Canada

A baseline for exposure to organochlorine and metal contaminants has been established for mothers and newborns in the Northwest Territories and Nunavut areas of Arctic Canada. Maternal and umbilical cord blood plasma organochlorine levels are described for Inuit, Dene, Métis, Caucasian and Other non-Aboriginal participants. Overall, 523 women volunteered to participate by giving their written informed consent between May 1994 and June 1999, resulting in the collection of 386 maternal blood samples, 407 cord blood samples and 351 maternal/cord pairs. Nearly half of all the participants regularly smoked cigarettes, including 77% of the Inuit participants. Maternal and cord results are presented for PCBs (as Aroclor 1260 and 14 congeners) and organochlorine pesticides, including p,p'-DDT, p,p'-DDE, beta-hexachlorocyclohexane (beta-HCH), hexachlorobenzene (HCB), cis and trans nonachlor, heptachlor epoxide, oxychlordane, mirex, dieldrin and toxaphene. Maternal PCB levels (as Aroclor 1260) averaged 4.42 (+/-9.03) microg/l in Inuit, which was 3.3 times higher than those found in Dene/Métis, and 3.4 times higher than levels in Caucasians. Mean DDE levels were 2.8 times higher in the Other non-Aboriginal group (Chinese, Filipino, East Indian and multiple ethnicity) than in the Inuit group, at 3.99 microg/l and 1.42 microg/l, respectively. Cord blood PCB levels (as Aroclor 1260) averaged 1.16 (+/-2.42) microg/l for Inuit participants, which was 3.3-4 fold higher than the other ethnic groups. PCBs, p,p'-DDE and hexachlorobenzene were detected in all maternal samples, and p,p'-DDE was detected in all cord samples. Regression coefficients for maternal/cord pairs are presented for selected organochlorines. Other results from this study, including maternal and cord metals data, will be presented elsewhere.     

Distribution of polychlorinated biphenyls in marine species from French Frigate Shoals, North Pacific Ocean

Polychlorinated biphenyls (PCBs) were analyzed in: sediment; coral (Porites evermanni); fish (Stegastes fasciolatus, Neoniphon sammara, Acanthurus triostegus and Mulloidichthys vanicolensis); crab (Grapsus tenuicrustatus); lobster (Panulirus marginatus); and eel (Conger cinereus, Gymnothoraxflavimarginatus, G. undulatus and G. meleagris) samples collected from Tern Island and the corresponding reference samples from Disappearing Island. The two islands are part of French Frigate Shoals, a national wildlife refuge in the North Pacific Ocean. The dominant congeners 118, 138 and 153 represent 22-25, 32-34, 12-39, 37-46 and 30-55% of the sum of PCBs in the coral, sediment, fish, crab and eel, respectively. In general, high trophic species such as eels were found to highly bioaccumulate PCBs. The total average PCB concentrations were as high as 96 and 29 microg/g dry wt. in eels and damselfish, respectively, from Tern Island. The localized behavior and high bioaccumulation potential for PCBs suggest that damselfish are an excellent species for monitoring PCBs in small areas in the ocean. The high average concentrations of the sum of PCBs in different food chain levels suggest that pollution source(s) are around Tern Island and possibly around Disappearing Island. Aroclor 1254 and its analogs are suspected sources responsible for PCBs in the samples.     

The influence of a capacitor plant in Serpukhov on vegetable contamination by polychlorinated biphenyls

PCB content in soil and vegetables grown on the polluted soils in some districts of the town of Serpukhov have been studied for 10 years after the use of PCBs had been banned at the local capacitor plant. Soil contamination with PCBs in the vicinity of the plant is still extremely high (up to 30 mg/kg). Vegetables grown on the polluted soils, especially carrots and green parts of fennel, parsley, celery are also highly contaminated. The primary pollutants are found to be tri- and tetrachlorobiphenyls (up to 70-80% of total PCBs).     

Distribution of polychlorinated biphenyls in a municipal wastewater treatment plant and environs.

Distribution of polychlorinated biphenyls (PCB) in sewage wastes at a municipal sewage treatment plant was studied, showing that the great bulk of PCBs entering such a treatment plant become adsorbed onto the grit chamber solids and the sludge that is passed from the anaerobic digesters. When appreciable quantities of PCBs are present in sewage, as was the case in this study, significant quantities can nevertheless pass with the effluents discharged from the treatment plant. The PCB concentrations in the treatment plant waters undergoing secondary and tertiary treatment tend to be consistent with the limited solubility properties of the PCBs. However, appreciably higher concentrations can be found in the sediments of waters receiving treatment plant discharges and bioaccumulation in fish is demonstrated readily. Also described are quantitative data on PCBs in soils fertilized with PCB-contaminated sludge.     

Persistent organic pollutants and mercury in dead and dying glaucous gulls (Larus hyperboreus) at Bjørnøya (Svalbard)

Dead and dying glaucous gulls (Larus hyperboreus) were collected on Bjørnøya in the Barents Sea in 2003, 2004 and 2005. Autopsies of the seabirds only explained a clear cause of death for three (14%) of the 21 birds. A total of 71% of the birds were emaciated. Liver and brain samples were analysed for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ether (PBDEs), hexabromocyclododecanes (HBCDs) and mercury (Hg). High levels of ΣOCPs, ΣPCBs, ΣPBDEs and α-HBCD were found in liver and brain. Compared to the dead and dying glaucous gulls found 1989, the congeners' composition tended to change toward more persistent compounds in the 2003–2005 samples. The brain levels of OCPs and PCBs did not differ between 1989 and 2003–2005, while the liver levels were significantly lower. The brain/liver ratio for PCB and PBDE significantly decreased with halogenations of the molecule, indicating a clear discrimination of highly halogenated PCBs and PBDEs entering the brain. There was further a clear negative correlation between contaminant concentrations and body condition. The brain levels were not as high as earlier published lethal levels of p,p′-DDE or PCB. However, more recent studies reported a range of sub-lethal OCP- and PCB-related effects in randomly sampled glaucous gulls. An additional elevation of pollutants due to emaciation may increase the stress of the already affected birds. The high brain levels of OCP, PCB and PBDE of present study might therefore have contributed to the death of weakened individuals of glaucous gull.     

The degradation of polychlorinated biphenyls by micro-organisms

An investigation is described concerning the effects of two micro-organisms cultures on single compounds and multi-component mixtures of polychlorinated biphenyls (PCBs).Several low chlorine PCB compounds can be degraded easily with these cultures and, in favourable circumstances, some compounds containing up to six chlorine atoms per molecule can be degraded.In certain multi-component commercial mixtures some PCB compounds are degraded more readily than if present singly. The significance of this is discussed, particularly the fact that work on single compounds does not enable predictions to be made about the behaviour of commercial mixtures in the environment. Some tentative explanations are suggested for the behaviour of the mixtures exposed to these cultures.     

2. The response of a laboratory stream system to PCB exposure: study of periphytic and sediment accumulation patterns

It has been proposed that the accumulation of PCBs by aquatic organisms is a physicochemical process that is governed by the equilibrium partitioning of PCBs between the organisms and the ambient water. This approach focuses primarily on the hydrophobicity of PCBs, while neglecting the biological impacts of PCB accumulation and possible differences in species-specific response. Furthermore, it does not reflect the complex mechanistic aspects of PCB accumulation. Current modeling, while focusing on accumulation via contaminated food, has been for large lake systems and is not appropriate for lower trophic organism interactions. The objective of this research was to evaluate the ecotoxicological fate of PCBs in a laboratory stream system and to determine if species-specific differences in the accumulation and toxic effects of PCBs existed. Bench scale experiments were conducted to determine kinetic and equilibrium parameters measuring algal uptake of PCB, and these results were used to explain the periphytic response to low level PCB exposure in the laboratory stream system. The results revealed that the accumulation rate, accumulation capacity and toxicity of PCBs differed for the species tested. The observation of PCB fate in the laboratory stream system indicated that PCB volatilization, sediment adsorption and periphyton bioaccumulation were the major pathways of PCB fate. The periphytic biolayer was the significant sink for PCB concentration. The accumulation capacity of periphytic biolayer to PCBs was one order of magnitude greater than that of sediments on a TOC basis. Comparison of the experimental data with model predictions illustrates that equilibrium partitioning models are not very accurate for predicting the accumulation of hydrophobic chemicals by low trophic biota.     

Selected persistent organochlorine pollutants in Romania

Selected persistent organochlorine pollutants, including PCBs, DDT and its metabolites (DDTs) and hexachlorocyclohexane isomers (HCHs) were determined in soil, animal fat and human serum samples from Romania. All methods were rigorously tested and adequate quality control was ensured. Soil samples from Iassy County showed a lower contamination with organochlorines than samples from other Romanian regions. While DDTs concentrations in soil were significantly higher at rural sites, only few samples (three out of 47) exceeded the official Romanian norms for DDTs. PCBs concentrations were low in rural sites (<8 ng/g soil), but rather high (up to 134 ng/g soil) in urban soils collected mostly from parks (Bucharest, Arad, Baia Mare, Pitesti and Ploiesti). Animal fat samples from Iassy showed high concentrations of organochlorine pesticides (HCHs concentrations up to 12370 ng/g fat), but similar PCB concentrations when compared with Arad samples. Two samples (from 24) exceeded the EU norms (1000 ng/g fat) for HCHs and DDTs in animal fat. Organochlorines were found in higher concentrations in some samples of human serum from Timisoara due to a broader age range. Samples of human serum from Iassy mothers showed higher HCHs and DDTs concentrations than samples from a similar group from Antwerp, Belgium. HCB and PCBs were higher in Antwerp cohort. Romanian samples showed a higher ratio DDT/ΣDDTs, but similar ratios PCB 153/ΣPCBs.     

Serum PCB profiles in Native Americans from Wisconsin based on region, diet, age, and gender: Implications for epidemiology studies

BACKGROUND: Different PCB congeners and different mixtures of congeners have been demonstrated to have different biological actions. More complete characterization of congener profiles in exposure sources may assist in predicting health outcomes. METHODS: Thirty-six (36) polychlorinated biphenyl (PCB) congeners were measured by gas chromatography isotope-dilution mass spectrometry (IDMS) in 314 serum samples from Native Americans in Wisconsin, Michigan and Minnesota. Five dietary groups were established based on the quantity and species of fish consumed and the waters from which the fish were caught. Multivariate statistical methods were able to resolve gender and dietary differences in PCB homologue and PCB congener patterns. RESULTS: Females had higher proportions of lower chlorinated homologues, including a consistently higher proportion of pentaCB 118. The relative presence of the very labile and volatile PCB 18, above 1% of the total PCB in females from the minimal fish consumption and "other" groups, suggests possible exposure to PCBs in the atmosphere. The dietary group consuming predatory fishes from Lakes Michigan and Superior had the highest serum concentrations of total PCB (mean of 3.1 ng/ml) and the most distinct congener profile. The two dietary groups least dependent on fishing or fishing mostly from inland lakes (non-Great Lakes) had the lowest total PCB concentrations, both with means of 1.4 ng/ml. CONCLUSIONS: These serum PCB concentrations were less than those found in earlier studies of fish consumers in the Great Lakes region and may reflect the decrease in PCBs in these lakes.