Vertical fluxes and accumulation of PCBs in coastal sediments of the Río de la Plata estuary, Argentina

Settling particles and underlying sediments collected at 1, 2.5 and 4 km along offshore transects in the urbanized sector of the Río de la Plata were analyzed to evaluate the sources and accumulation of PCBs. Total PCB concentrations range from <0.1 to 100 ng g(-1) and include variability associated to North-South and offshore gradients reflecting the impact of coastal discharges. Highest concentrations were recorded in the industrialized Central area close to Buenos Aires (61+/-37 ng g(-1) at 1 km) relative to cleaner northern stations (3.6+/-2.2 ng g(-1)) and southward sites (37+/-2.8 ng g(-1)), affected by transport of particulate PCBs by coastal currents. Sediment traps deployed in the Central area revealed large depositional fluxes of total matter (361+/-124 gm(-2)day(-1)) and PCBs (26+/-19 microg m(-2)day(-1)) and high sedimentation rates (5.0+/-1.7 cm yr(-1)). Uniform PCB concentrations (66-89 ng g(-1)) down to 20 cm in sediment cores suggest continued PCB discharges during the last 4 years. PCB composition was dominated by hexa (43+/-6.4%), hepta (23+/-5.1%) and pentachlorobiphenyls (21+/-5.5%) with lower proportions tri-tetra (7.4+/-5.4%) and higher chlorinated congeners (5.1+/-3.3%). A consistent weathering pattern with loss of 3-5 chlorobiphenyls and enrichment in higher chlorinated PCBs corresponding to a shift from a 1:1 to a 1:3 1254:1260 Aroclor mixture, was observed offshore. A principal component analysis performed with the relative contribution of PCB congener classes confirmed the offshore weathering pattern indicating that transformer oils containing Aroclor 1254-1260 are the most probable sources. Sediment inventories, sediment trap fluxes and Fugacity II calculations indicate an accumulation approximately 500-800 kg PCB in superficial sediments of this coastal environment.     

Comparative distribution, sourcing, and chemical behavior of PCDD/Fs and PCBs in an estuary environment

PCDD/F and PCB field data (1041 samples) in five media (dissolved, suspended sediment, bed sediment, catfish, and blue crab) were studied to explore dual contaminant patterns in the Houston Ship Channel, Texas, USA. PCDD/Fs showed greater concentration than PCBs in suspended sediments while PCBs were higher in apparent dissolved (truly dissolved + DOC-associated), fish, and crab. PCDD/Fs at nearly all locations contributed more strongly to dioxin-like toxicity. The fraction of PCB TEQ was, however, enriched in biotic over abiotic media due in large part to the presence of PCB 126, which was mostly undetected in water and sediment and yet exhibited a BAF three times greater than 2,3,7,8-TCDD. Dissolved-suspended sediment and suspended-bed sediment relationships showed that (1) observed apparent dissolved concentration differences (as fraction of total water were mean 10% PCDD/Fs and 63% PCBs) can reasonably be explained by a four-phase partition model (truly dissolved, DOC-associated, suspended OC, and suspended BC) for PCBs but not for PCDD/Fs and (2) the contaminants behaved similarly in bed to suspended sediment concentration ratios (C_bed/C_susp) upstream of a major confluence but not downstream. PCA-cluster analysis pointed to the possibility that suspended sediment PCB contamination originates from resuspended bed sediment while PCDD/Fs in suspended sediment originates more probably from other sediment sources such as upstream wash load or air deposition. Finally, examinations of a congener marker ratio (PCB 209/206) seemed to indicate that a source of pure PCB 209 may exist in bed sediment near Patrick Bayou though the source was not completely localized.     

Levels,congener profile and inventory of polychlorinated biphenyls in sediment from the Songhua River in the vicinity of cement plant,China: a case study

This study investigated the contamination levels, homologue, and congener profiles and evaluated the residue inventory of polychlorinated biphenyls (PCBs) in sediment of the Songhua River in the vicinity of cement plant. The total concentration of detected 35 PCB congeners ranged from 1.12 to 2.19 ng/g dry weight (dw) in sediment, with a mean value of 1.56 ng/g dw, and the concentration of PCBs decreased in the following order: the downstream?>?cement plant?>?upstream. The results of total organic carbon (TOC)-normalized PCB concentrations indicate that the sediments have low potential ecological risk in this area. The study results on homologue and congener of PCBs show that the emissions from cement production could be the major sources of PCBs in sediment, and the low-chlorinated PCBs will be exchanged among air, water, and sediment with increasing temperature during summer and flow to downstream with water during the wet season. The spatial density and total burden of PCBs in the surface sediments were 17.2 ng/cm² and 1.2 kg, respectively. To our knowledge, this study is the first to explore the pollution characteristics of unintentionally produced PCB emissions from cement industry by means of monitoring sediment samples.     

PCDD/F and PCB multi-media ambient concentrations, congener patterns and occurrence in a Mediterranean coastal lagoon (Etang de Thau, France)

Ambient concentrations, congener patterns and multi-media distribution of PCDD/Fs and PCBs were determined in air, water, sediment and mussels in a semi-enclosed marine ecosystem (Thau lagoon, France). summation operator2,3,7,8-PCDD/F and summation operator7ICES PCB air concentrations (0.2-1.4 and 31-57pg m(-3), respectively) were typical of rural areas. Concentrations in the water column were very low for PCDD/Fs (163-476fg L(-1)) and low for PCBs (138-708pg L(-1)). PCDD/F and PCB concentrations found in surface sediment (0.15-1.6 and 2.5-33ng g(-1) d.w., respectively) and mussel (13-21pg g(-1) d.w. and 10-39ng g(-1) d.w., respectively) were medium levels. PCDD/F congener patterns observed in air, water particulate phase and sediments were similar suggesting direct coupling among these compartments and atmospheric inputs of PCDD/Fs into the lagoon. Conversely, for the same set of samples, similar patterns were not observed for PCBs in the mentioned compartments.     

PCB accumulation in osprey exposed to local sources in lake sediment

We examined the accumulation of PCBs in ospreys (Pandion haleaetus) that were exposed to local sediment sources. Eggs, chick plasma, and sediment samples were collected over a range of 14 km (0.2-14.2 km) from a PCB source in Sturgeon Lake, ON. Sum PCB concentrations declined in chick plasma (range 422.5-58.3 ng/g) as distance from the PCB source increased, but there was a poor relationship with sum PCBs in eggs. Both tissues indicated an Aroclor 1248/1254 source. Aroclor 1254 comprised an average of 66.9% of sum PCBs in chick plasma from Sturgeon Lake, but comprised only from 27.0 to 44.4% in plasma from other Great Lake colonies. Dietary differences among osprey colonies were not sufficient to explain the PCB patterns observed. There was weak evidence that the ability to metabolize PCBs may differ between juveniles and adults, based upon the PCB profile in eggs and chick plasma.     

Comparison of an enzyme-linked immunosorbent assay (ELISA) to gas chromatography (GC)--measurement of polychlorinated biphenyls (PCBs) in selected US fish extracts

The analysis of PCBs in fish tissues by immunoassay methods was evaluated using fish collected from a US monitoring program, the National Contaminant Biomonitoring Program of the US Department of Interior, Fish and Wildlife Service. Selected composite whole fish samples, which represented widely varying concentrations and sources of PCBs, were extracted and subjected to congener PCB analysis by gas chromatography (GC) and total PCB analysis using an ELISA (ePCBs) calibrated against technical Aroclor 1248. PCB congener patterns in these fishes were different from the patterns found in commercial Aroclors or their combinations as demonstrated by principal component analysis of normalized GC congener data. The sum of the PCB congeners measured by GC (total-PCBs) ranged from 37 to 4600 ng/g (wet weight). Concentrations of PCBs as determined by the ELISA method were positively correlated with total-PCBs and the ePCBs/total-PCBs ratios for individual samples ranged from 1 to 6. Ratios of ePCBs/total-PCBs for dilutions of Aroclors 1242, 1254, and 1260 and for matrix spikes range from 0.6 for 1242 to 2.5 for 1254 and 1260. These results suggest that higher chlorinated PCB congeners have higher affinity for the anti-PCB antibodies. Partial least squares with latent variable analysis of GC and ELISA data of selected Aroclors and fish samples also support the conclusion that ELISA derived PCB concentrations are dependent on the degree of chlorination.     

Polychlorinated biphenyls in Narragansett Bay surface sediments

Polychlorinated biphenyls (PCBs) were evaluated in 41 surface sediments collected from Narragansett Bay, RI in 1997-1998. Highest concentrations of total PCBs (1760 ng/g) were in rivers at the head of the bay and the values decreased southward toward the mouth of the bay, with elevated concentrations in some of the coves. The PCB levels in approximately 43% of the samples exceeded the effects range median (ERM) guideline [Environ. Manage. 19 (1995) 81] indicating possible adverse biological effects at these stations. Principal component analysis (PCA) of the surface sediment PCBs separated the Taunton River samples from the rest of the samples. This result suggests that this river has a different PCB composition and sources than the other areas investigated. It also showed that this river has a limited influence on other bay stations as the adjacent samples downstream did not have the same chemical signature. Congener ratios derived from the PCA were useful in distinguishing stations that had different sources of PCBs than the bulk of the bay sediments. Although Aroclor 1268 and 1270 accounted for <1% of all PCB production, their major components, CB206 and CB209, account for 3-6% of the CBs in most bay samples. This may reflect more local use of these Aroclor mixtures and/or be indicative of their relative stability, compared to less chlorinated mixtures. Using linear alkyl benzenes (LABs) as a marker for sewage derived PCBs suggested that up to 95% of the PCBs at the most contaminated sites in the Seekonk, Providence, and Taunton Rivers were sewage derived. This analysis also showed that there is a high background level (167 ng/g) of PCBs in the Seekonk and Providence River, while the Taunton River had a relatively low background level (23.7 ng/g). At the furthest stations south in the Providence River, the sewage derived PCBs only accounted for 23% of the total which suggests that PCB associated with sewage particles are rapidly deposited and are therefore not the most significant source of these compounds to the lower reaches of Narragansett Bay.     

Isotope dilution analysis of polychlorinated biphenyls (PCBs) in transformer oil and global commercial PCB formulations by high resolution gas chromatography-high resolution mass spectrometry

Special polychlorinated biphenyls (PCBs) standards (native and isotope labeled) were analyzed by isotope dilution method using HRGC-HRMS. Multiple analysis of special PCBs standards by three different laboratories produced the relative response factors (RRFs) and relative standard deviations (RSDs %) was in the average of 0.979 and 3.86, respectively. Additionally, inter-laboratory analysis of various forms of transformer oil revealed the PCBs concentrations were in the following order; PCBs fortified transformer oil (940-1300 ng/g)>PCB polluted transformer oil (490-680 ng/g)>chemically degraded-transformer oil (480-490 ng/g) and PCBs free oil (ND-17 ng/g). Chemical degradation resulted in an order of magnitude decrease in the PCB concentrations. Specifically, higher chlorinated PCBs degraded into lower chlorinated PCBs. Also, composition of PCBs have been determined in PCB formulations from Japan (Kanechlor), Germany (Clophen), USA (Aroclor), Russia (Sovol) and Poland (Chlorofen). Major PCBs (24-PCB congeners) contributed 54-67%, 55-68%, 16-69%, 71% and 72% in Kanechlor, Clophen, Aroclor, Sovol and Chlorofen, respectively to total PCBs. The homologue pattern of Kanechlor, Aroclor and Clophen in technical fromulation was similar (e.g., Kanechlor-300 resembled to those of Clophen A-30 and Aroclor-1242). Furthermore, congener-specific distributions of major PCBs/dioxin-like PCBs and toxic equivalency quantities (TEQ) were calculated. Based on our tentative assumption calculations, cumulative production of five different technical PCB formulations, WHO-TEQ emission was estimated to be approximately 16.05 tons.     

Organochlorine and mercury contamination in fish tissues from the River Nestos, Greece

Polychlorinated biphenyls (PCBs), hexachlorocyclohexane (HCH) isomers, dichlorodiphenyltrichloroethane (DDT) and its metabolites, other organochlorine pesticides such as hexachlorobenzene (HCB), chlordane compounds (CHLs, including trans-chlordane and cis- and trans-nonachlor) and the heavy metal mercury were quantified in muscle and liver of the European chub (Leuciscus cephalus, Linnaeus, 1758) and in the muscle of the barbel (Barbus cyclolepis, Heckel, 1837) at two sampling sites of the River Nestos, Greece. PCBs in muscle and DDTs in the liver tissues were the predominant organochlorinated contaminants. Among the PCBs, congeners 47 (up to 9.60 ng g(-1) wet wt.), 180 (up to 1.15 ng g(-1) wet wt.) and 190 (up to 1.50 ng g(-1) wet wt.) were the most frequent and abundant. The contamination degree by the sum of PCBs on the fish tissue samples from the River Nestos is lower or similar to PCB levels found in other ecosystems. Among the organochlorine pesticides, essentially only p,p'-DDD, p,p'-DDE and alpha-, beta- and gamma-HCH were found, with the former appearing at mean levels up to 30.71 ng g(-1) wet wt. From a public health standpoint, residue organochlorine pesticide levels from our work are considerably lower than the recommended tolerance limits. Finally, mean values of Hg in chub were significant lower (up to 31.04 ng g(-1) wet wt.) compared to those detected on barbel (up to 169.27 ng g(-1) wet wt.). The concentrations of Hg in fresh water fish from the River Nestos did not exceed WHO and US EPA health guidelines, and were suitable for human consumption.     

Record of PCB congeners, sorbents and potential toxicity in core samples in Indiana Harbor and Ship Canal

Indiana Harbor and Ship Canal (IHSC) is an active navigational system that serves a heavily industrial area of southern Lake Michigan. We have determined the amount of polychlorinated biphenyls (PCBs), congener distributions, sorbent types and potential for dioxin-like PCB toxicity from two IHSC sediment cores. Vertical distributions of ΣPCBs (sum of 161 individual or coeluting congeners) ranged from 410 to 91000 and 1800 to 41000 ng g(-1) dry weight (d.w.) for cores 1 and 2, respectively. Core 1 showed its highest accumulation rate for the year ～1979 and exhibits a strong Aroclor 1248 signal in sediments accumulating over the last 60 years. It appears that from the late 1930s until the beginning of the 1980s there was a large and constant input of PCBs into this system. This pattern differs from lake cores from the Great Lakes region which commonly exhibit a rapid increase, a peak, followed by a sharp decrease in the PCB accumulation rates. Core 2 also has a strong Aroclor 1248 signal in the top layers, but deeper layers show evidence of mixtures of Aroclors and/or weathering processes. High levels of black carbon as a fraction of total organic carbon were found in both cores (median ～30%), which reflect the long history of local combustion sources. No strong relationship was found between ΣPCB concentration and sorbents. Both cores contain dioxin-like PCBs that are highest in concentration below the surface. The high levels of PCBs in the deep sediments are of concern because of plans to dredge this system.     

Bioaccumulation of PCBs in the cuttlefish Sepia officinalis from seawater, sediment and food pathways

The cuttlefish Sepia officinalis was selected as a model cephalopod to study PCB bioaccumulation via seawater, sediments and food. Newly hatched, juvenile cuttlefish were exposed for 17 days to environmentally realistic concentrations of (14)C-labeled 2,2',4,4',5,5'-hexachlorobiphenyl (PCB#153) (18 ng PCB l(-1) seawater; 30 ng PCB g(-1) dry wt sediments; Artemia salina exposed to 18 ng PCB l(-1) seawater). Accumulation of PCB#153 was followed in three body compartments: digestive gland, cuttlebone and the combined remaining tissues. Results showed that (1) uptake kinetics were source- and body compartment-dependent, (2) for each body compartment, the accumulation was far greater when S. officinalis was exposed via seawater, (3) the cuttlebone accumulated little of the contaminant regardless of the source, and (4) the PCB congener showed a similar distribution pattern among the different body compartments following exposure to contaminated seawater, sediment or food with the lowest concentrations in the cuttlebone and the highest in the remaining tissues. The use of radiotracer techniques allowed delineating PCB kinetics in small whole organisms as well as in their separate tissues. The results underscore the enhanced ability of cephalopods to concentrate organic pollutants such as PCBs, and raise the question of potential risk to their predators in contaminated areas.     

Occurrence of PAHs, PCBs and organochlorine pesticides in the Tonghui River of Beijing, China

Tonghui River, a typical river in Beijing, People's Republic of China, was studied for its water and sediment quality, by determining the levels of 16 polycyclic aromatic hydrocarbons (PAHs), 12 polychlorinated biphenyls (PCBs) and 18 organochlorine pesticides in water and sediment samples. Total PAHs, PCBs and organochlorine pesticides concentrations in water varied from 192.5 to 2651 ng/l, 31.58-344.9 ng/l and 134.9-3788 ng/l, respectively. The total PAHs, PCBs and organochlorine pesticides concentrations in surficial sediments were 127-928 ng/g, 0.78-8.47 ng/g and 1.79-13.98 ng/g dry weight, respectively. The results showed that the concentration of these selected organic pollutants in sediment was higher than those in surface water. It may be due to the fact that organic hydrophobic pollutants tend to stay in the sediments. The PAHs were dominated by 2-, 3-ring components in water samples and by 3- and 4-ring compounds in sediment. For organochlorines, alpha-HCH, delta-HCH, Heptachlor, Endosulfan II, DDT are the major organochlorine pesticides in water while Heptachlor, Dieldrin and DDE composed of 95% of total organochlorine pesticides in sediment. For HCHs (HCHs=alpha-HCH+beta-HCH+gamma-HCH+delta-HCH), the predominance of alpha-HCH of total HCHs were clearly observed in water and sediment. PCB18, PCB31 and PCB52 were predominant in water, on average these compounds collectively accounted for 67% of total PCBs. But in sediment, the predominant compounds were PCB28, PCB31 and PCB153, which accounted for 71% of total PCBs in sediment. The levels of micro pollutants in our study areas were compared with other studies.     

Characterization of contaminants in snapping turtles (Chelydra serpentina) from Canadian Lake Erie Areas of Concern: St. Clair River, Detroit River, and Wheatley Harbour

PCBs, organochlorine pesticides and dioxins/furans in snapping turtle eggs and plasma (Chelydra serpentina) were evaluated at three Areas of Concern (AOCs) on Lake Erie and its connecting channels (St. Clair River, Detroit River, and Wheatley Harbour), as well as two inland reference sites (Algonquin Provincial Park and Tiny Marsh) in 2001-2002. Eggs from the Detroit River and Wheatley Harbour AOCs had the highest levels of p,p'-DDE (24.4 and 57.9 ng/g) and sum PCBs (928.6 and 491.0 ng/g) wet weight, respectively. Contaminant levels in eggs from St. Clair River AOC were generally higher than those from Algonquin Park, but similar to those from Tiny Marsh. Dioxins appeared highest from the Detroit River. The PCB congener pattern in eggs suggested that turtles from the Detroit River and Wheatley Harbour AOCs were exposed to Aroclor 1260. TEQs of sum PCBs in eggs from all AOCs and p,p'-DDE levels in eggs from the Wheatley Harbour and the Detroit River AOCs exceeded the Canadian Environmental Quality Guidelines. Furthermore, sum PCBs in eggs from Detroit River and Wheatley Harbour exceeded partial restriction guidelines for consumption. Although estimated PCB body burdens in muscle tissue of females were well below consumption guidelines, estimated residues in liver and adipose were above guidelines for most sites.     

Concentrations of dioxin-like PCB congeners in unweathered Aroclors by HRGC/HRMS using EPA Method 1668A

We have determined the congener compositions of nine commercial Aroclor products of polychlorinated biphenyls (PCBs) to the sub-part-per-million level using high-resolution gas chromatography combined with high-resolution mass spectrometry according to US Environmental Protection Agency (EPA) Method 1668A. These Aroclor composition data should allow improved characterization and risk assessment of PCB contamination at hazardous waste sites, particularly for dioxin-like PCB congeners. By combining the data on the concentrations of each dioxin-like congener with its World Health Organization toxicity equivalency factor, we have established dioxin toxic equivalent concentrations for each pure Aroclor product.     

Spatial distribution and source apportionment of PCBs in sediments around İzmit industrial complexes, Turkey

The spatial distribution, degree of pollution and major sources of PCBs were evaluated in surficial sediments within the heavily urbanized and industrialized ?zmit Bay and its main freshwater inputs. ΣPCB concentrations range from 2.90 to 85.4ngg(-1) in marine sediments and from ND to 47.7ngg(-1) in freshwater sediments. Results suggest that high concentrations of ΣPCBs were localized around a chlor-alkali plant and an industry that handles bulk liquid, dry and drummed chemicals, and petroleum products in the Bay. Using a chemical mass balance receptor model (CMB), major sources of PCBs in the region were investigated. The CMB model identified Aroclor 1254 and 1260 to be the major PCB sources in marine sediments and the less chlorinated Aroclor 1248 and 1242 as the major PCB sources in freshwater sediments. The potential sources for the PCBs were briefly discussed in terms of their use in various industrial applications.     

Distribution characteristics of polychlorinated biphenyls in crucian carp (Carassius auratus) from major rivers in Korea

Polychlorinated biphenyls (PCBs) levels in crucian carp were determined at 20 locations along four major river systems, several small-scale rivers and a wetland in Korea. Twenty-eight congeners, ranging from tri- to hepta-CBs were detected. A gas chromatograph with a mass selective detector was used to quantify the individual PCB congeners. The objectives of this study were to investigate the levels of contamination of PCBs in freshwater fish and to observe the pattern of their distribution. The sampling locations were chosen among 31 sampling sites that are currently used as environmental residue checkpoints by the Korean Ministry of Environment. Concentrations of individual congeners ranged from not detectable (n.d.) to 0.75 ng g(-1) on a wet weight basis. The total concentrations of PCBs at each site ranged from n.d. to 5.41 ng g(-1) of wet weight. The most heavily contaminated site was the Nakdong estuary located near the Shinpyung-Janglim factory district. The PCB 153 and 138 were the principal congeners and penta- and hexa-chlorinated biphenyls comprised the main congener groups.     

Polybrominated diphenyl ethers (PBDEs) in sediment and bivalves from Korean coastal waters

Concentrations of polybrominated diphenyl ethers (PBDEs) were determined in sediment and bivalves collected from 25 coastal locations in Korea. Twenty major PBDE congeners were found in all sediment and bivalve samples. SigmaPBDE20 concentrations ranged from 0.45 to 494 ng/g, dry weight (average 27.8 ng/g dry weight) in sediments, and from 0.38 to 9.19 ng/g, wet weight (average 2.94 ng/g wet weight) in bivalves. The highest concentrations were found at locations near industrial complexes and large harbors, suggesting that human activities contribute to PBDEs contamination in Korean coastal environment. PBDE concentrations measured in our study, excluding BDE congener 209 (deca-BDE), in sediment and bivalves were lower than those reported from other countries; whereas BDE 209 concentrations were comparable to or higher than those reported from other countries. The predominant PBDE congener in sediments and bivalves was deca-BDE, which accounted for >90% and >60% of the total PBDE concentrations in sediment and bivalves, respectively. This is consistent with high consumption of deca-BDE for the flame-retardant market in Korea. Significant correlations existed among BDEs 28, 47, 99, 100, 153 and 154 in sediments and bivalves; however, BDEs 183 and 209 showed little correlation compared with less highly brominated congeners.     

Placental transfer of polychlorinated biphenyls, their hydroxylated metabolites and pentachlorophenol in pregnant women from eastern Slovakia

The aim of the present study was to understand the placental transfer of polychlorinated biphenyls (PCBs), specific hydroxylated PCB metabolites (OH-PCBs), and pentachlorophenol (PCP) in blood serum, in a birth cohort from eastern Slovakia. During the period 2002-2004, cord blood specimens were collected in parallel with maternal specimens from women delivering in the two eastern Slovak districts of Michalovce and Svidnik/Stropkov. A total of 92 pairs of mother-cord specimens at delivery were selected for this study. 4-OH-CB107, 3-OH-CB153, 4-OH-CB146, 3'-OH-CB138, 4-OH-CB187, and 4'-OH-CB172 were quantified. The median concentrations of Sigma(17)PCBs, Sigma(6)OH-PCBs, and PCP in cord serum were 0.92, 0.33, and 0.69 ng/g wet wt., respectively and highly correlated with the corresponding maternal serum levels (correlations were R(2)=0.61, 0.78, and 0.82, respectively). The median cord to mother ratios of the Sigma(17)PCBs, Sigma(6)OH-PCBs, and PCP were 0.18, 0.75, and 1.10, respectively. The median ratio of the Sigma(6)OH-PCBs to the Sigma(17) PCBs in the cord serum was 0.38 from wet weight based concentrations, which was about four times higher than the ratio of these compounds in maternal serum (0.09). PCP was more abundant than any PCB or OH-PCB congener measured in cord serum. The higher cord to maternal ratios of OH-PCB metabolites as compared with the parent compounds suggests either a higher placental transfer rate or greater metabolism in the fetus as compared with the maternal compartment. These findings are consistent with their preferential binding to TTR that can cross the placenta. The cord to maternal ratio varies by congener (e.g., 4-OH-CB107=0.58, 4-OH-CB146=0.74, 3'-OH-CB138=1.01).     

Review on persistent organic pollutants in the environment of Greenland and Faroe Islands

The literature concerning persistent organic pollutants (POPs) in the environment of Greenland and the Faroe Islands covering the period up to 1995 has been revisited. It is difficult to compare data from earlier studies with those from more recent investigations. Thus as the former quantified the content of CBs by comparison to a technical mixture of CBs (e.g. Aroclor 1254), the latter analyses typically are quantified on a single congener level. Single CB congeners have in some cases been determined, but the results were subsequently expressed as total PCB related to an Aroclor standard. For studies based on single CB congener determinations, the highest levels are reported for porpoise blubber from Greenland (700-4500 micrograms/kg wet weight), the conclusion, however being based on two determinations only. In Greenlandic seal blubber and peregrine falcon plasma equal levels of CBs (130-750 micrograms/kg ww) and of DDTs (150-860 micrograms/kg ww) were found. Levels of CBs and DDTs in fish liver were found to be around 40-75 micrograms/kg ww. In sediment samples the CBs were almost all below the detection limit (< 0.02-0.1 microgram/kg dry weight), and thereby being the matrix with the lowest CBs concentration levels. Earlier data based on Aroclor standards showed DDT levels in Greenlandic whale blubber in the range of 2700-4100 micrograms/kg ww and PCB levels of 3700 micrograms/kg-5400 micrograms/kg ww. DDT levels for seal blubber were at the same level (2700-4500 micrograms/kg ww) whereas the PCB level was lower (900-3900 micrograms/kg ww). The PCB level corresponds to the level found in human adipose tissue determined with a similar quantification technique. The lowest levels reported for mammals correspond to walrus blubber, the sum of PCBs and DDTs being in the ranges of 180-360 micrograms/kg ww and 50-90 micrograms/kg ww, respectively. The content of PCBs in scallops was found to be 3 micrograms/kg ww near the Thule Air base.     

PCDD/F and PCB history in dated sediments of a rural lake

Concentrations of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and biphenyls (PCB) were analysed from a sediment core, which had been sampled from a remote lake in Finland. The deepest subsamples were analysed from a depth of 4.0 m, and were more than 8000 years old. At the surface of the sediment core, low levels of industrial background contamination were detected. The sum of 2,3,7,8-substituted PCDD/Fs was 35 ng/kg d.w. (dry weight), or 1.2 ng/kg d.w. in WHO's toxicity equivalent, WHO-TEQ. The annual accumulation rate of 2,3,7,8-substituted PCDD/Fs was 1.26 ng m(-2) a(-1). Deeper in the core, PCDD/F concentrations ranged between 2.11 and 11.1 ng/kg d.w. (0.24 and 1.70 ng/kg d.w. WHO-TEQ) and the accumulation rate was 0.11 ng m(-2) a(-1). A characteristic PCDD/F congener profile was found in all pre-industrial sediment layers. The order of concentrations was OCDD > 1,2,3,4,6,7,8-HpCDD > 1,2,3,7,8,9-HxCDD > 1,2,3,4,7,8-HxCDD > 2,3,7,8-TCDD, and concentrations of 2,3,7,8-chlorinated dibenzofurans were below the detection limit. Similar congener profiles have previously been described in samples for which natural PCDD/F formation has been proposed. PCBs were present at low levels in all of the sediment samples. The sum of the PCB concentrations of the sediment subsamples ranged between 50 and 2540 ng/kg d.w., and the three predominant congeners in the core were PCBs 18, 52, and 110.