Polychlorinated Biphenyls Uptake Research Articles

PCB uptake and accumulation by oysters ( Crassostrea virginica) exposed via a contaminated algal diet

Reproductively active oysters were fed daily with 0.2 g algal paste containing 0, 0.1, and 1.0 μg polychlorinated biphenyls (PCBs) (1:1:1 mixture of Aroclor 1242, 1254 and 1260) for either 15 or 30 days, and accumulation of PCBs in different organ tissues and eggs assessed. The effects of PCB exposure on lipid content, lipid class and fatty acid composition were also evaluated. PCBs were accumulated by the oysters and transferred to the eggs. PCB accumulation in oysters was dose, time and tissue dependent. Mean PCB contents were 3150, 1970, and 250 ng/g dry wt., respectively, in the visceral mass, gills+mantle and muscle of oysters fed algal paste containing 1.0 μg PCBs for 30 days. The PCBs in the eggs from the same oysters reached 671 ng PCBs/g dry wt. Feeding oysters with PCB-sorbed algal paste for 30 days significantly increased phospholipid and free fatty acid contents in gills+mantle tissues compared to the same tissues in the undosed control.

Ecological risk assessment of polychlorinated biphenyl contamination in the Mai Po Marshes Nature Reserve, Hong Kong

The main objective of the present study was to investigate polychlorinated biphenyl (PCB) contamination in Mai Po Marshes Natural Reserve, Hong Kong. During June–December 1997, samples of sediments and aquatic organisms including fish ( Oreochromis mossambica× O. nilotica, Mugil cephalus) and shrimps ( Metapenaeus ensis, Macrobrachium nipponense), were collected from gei wais and total PCB levels were measured. The concentrations of PCBs in sediments reduced gradually from coastal sites (8.13 ng g −1 dry wt) to landward sites (1.47 ng g −1 dry wt), which suggested that PCBs in Deep Bay waters were the main input source entering the reserve. The calculated PCB concentrations in water were generally safe for aquaculture according to the U.S. EPA guidelines, but PCBs in muscle tissues of grey mullet ( Mugil cephalus) exceeded the guidelines. PCB concentrations (ng g −1 lipid) in tilapia increased with increases in fish body size, which was possibly due to active uptake of PCBs by tilapia. Within the same shrimp species, different sized organisms showed similar PCB contents in lipid, indicating that lipid content rather than body size determined body concentrations. The PCB concentrations in the aquatic organisms in the reserve posed no hazards to birds according to predicted egg toxicity effects. The estimated BSAFs (biota-sediment accumulation factors) obtained in the present study ranged from 1.10 to 2.37, which were similar to the reported value of 2.10 derived from various aquatic biota species.

Effect of fatty acids and the aqueous diffusion barrier on the uptake and transport of polychlorinated biphenyls in Caco-2 cells

Polychlorinated biphenyls (PCBs) dissolved in dietary fat are absorbed in the gastrointestinal tract by the enterocytes in combination with the fatty acids proceeding from the lipid hydrolysis in the gut lumen. The effect of fatty acid absorption on the uptake and transport of 14 PCBs in enterocytes was studied using monolayers of the human intestinal Caco-2 cell line as a model system. The diffusive resistance of the unstirred water layer and the facilitating role of mixed bile salt micelles on the PCB uptake were examined by varying the thickness of the unstirred water layer adjacent to the apical membrane. In additional experiments, the polarity of the PCB uptake and transport in Caco-2 cells was determined. The solubility of PCBs in the mixed bile salt-fatty acid micelles was 2.7 to 4.8-fold higher than the solubility in plain bile salt micelles. Both the uptake and transport of PCBs in Caco-2 cells were significantly higher (up to 10-fold) when the PCBs were presented mixed with fatty acids. Reducing the thickness of the unstirred water layer resulted in an increased uptake of PCBs. The PCB uptake in Caco-2 cells exceeded the uptake as expected from monomer diffusion only, indicating that bile salt micelles facilitate the PCB transport over the unstirred water layer. Concentrations of dichlorobiphenyls accumulating in the basolateral medium stayed unexpectedly low, suggesting that Caco-2 cells might possess the capability of metabolizing lower chlorinated biphenyls. Uptake of PCBs into the Caco-2 cells was not significantly different whether the PCBs were presented at the apical side or at the basolateral side. However, transport of PCBs over the cell monolayer was significantly higher when the PCBs were presented at the apical side as compared to the basolateral side, suggesting that the unidirectional transport of lipids and lipoproteins affected the PCB transport as well. Our studies indicate that monolayers of the Caco-2 cell line offer a useful model system for studying the intestinal uptake and transport processes of hydrophobic xenobiotics such as polychlorinated biphenyls.

Caged mussels and semipermeable membrane devices as indicators of organic contaminant uptake in dorchester and duxbury bays, Massachusetts

AbstractAn experiment to measure organic contaminant depuration by the blue mussel (Mytilus edulis) was carried out by transplanting mussels in stainless steel cages from a known contaminated site in Dorchester Bay, Massachusetts to a documented clean site in Duxbury Bay, Massachusetts approximately 30 nmi south of the original collection site. A parallel contaminant uptake experiment was performed in which mussels from Duxbury Bay were collected and deployed in similar cages in Dorchester Bay. The bivalves were collected from each transplant site at set intervals over a period of 95 days to monitor the rates and selectivity of depuration and uptake, respectively, of polynuclear aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and chlorinated pesticides. In a related study, semipermeable membrane devices (SPMD: polyethylene bags) containing the lipid material triolein were deployed in Dorchester Bay and collected at the same frequency as the caged mussels to evaluate their effectiveness as models for estimating bioconcentration of target organic contaminants. At the Duxbury site, results suggest that the caged mussels depurated contaminants within 68 days to levels found in native animals at the site. At the Dorchester site, bivalves concentrated the contaminants to a level similar to the native M. edulis. PCB and DDT uptake rates were found to be similar between caged mussels and SPMDs; PAH uptake by the SPMDs was initially lower than by transplanted bivalves. PCB and PAH assemblages were noticeably different between bivalves and SPMDs deployed at the same site.

Bioaccumulation of PCBs by algae: Kinetics versus equilibrium

AbstractThe objectives of this study were to test the hypothesis that bioaccumulation of hydrophobic organic compounds (HOCs) by phytoplankton is correlated to the compound's octanol/water partition coefficient (Kow) in a predictive relationship in laboratory experiments, and to confirm these findings with field observations. In laboratory experiments we measured the uptake of 40 representative polychlorinated biphenyl (PCB) congeners over time under conditions that inhibited and allowed phytoplankton growth. Results indicated that the bioaccumulation process is consistent with partitioning from water into cell lipids but is slower than previously thought. The uptake of PCBs was slow relative to growth of phytoplankton, preventing the chemical from reaching thermodynamic equilibrium in algal cells under conditions promoting growth (nonwinter). Thus under non‐winter field conditions, many PCB congeners never reach equilibrium concentrations. Food‐chain models that assume equilibrium between HOCs and the primary trophic level could be inaccurate and may need to use a kinetic framework.

Determinants of the short-term dynamics of PCB uptake by plankton

Many studies relate the ecological fate of a contaminant to its chemical structure, but few combine quantitative structure-activity relationships with environmental properties that may modulate those effects, so the modulating role of such properties remains unquantified. This study determines the effects of variations in suspended biomass, dissolved and colloidal organic carbon, and pH on the time course of 2, 2[prime], 4, 4[prime], 5, 5[prime]-hexachlorobiphenyl uptake by laboratory cultures of Selenastrum capricornutum Printz. Variations in pH had no effect, but uptake increased with biomass and decreased at higher levels of organic carbon, measured as absorbance at 440 nm (Abs, per meter). Coefficients for these effects combined with existing relations based on simple first-order molecular connectivity ([chi]) or capacity ratio (K[prime]) yielded semi-empirical equations to predict the instantaneous rate of uptake and bioconcentration factor (BCF) of organic contaminants: log rate = [minus]3.30 + 0.32[chi] + 1.1 log biomass [minus] 0.42 log Abs; log BCF = 4.11 + 0.86 log K[prime] [minus] 0.87 log biomass [minus] 0.22 log Abs. These equations, entirely based on pure laboratory cultures, were assessed by comparing predicted uptake with the time courses of polychlorinated biphenyl (PCB) uptake by plankton in water from 11 Quebec lakes and proved tomore » be more effective than predictions based on contaminant properties alone.« less

Effects of pH and humus on the availability of 2,2′,4,4′,5,5′-hexachlorobiphenyl-14C in lake water

The effects of treatments of lake water with lime and acid on the availability of 2,2′,4,4′,5,5′-hexachlorobiphenyl to aquatic organisms were studied. A closed laboratory system with hexane-filled dialysis bags of two pore sizes was used, in combination with a 14C-labeled PCB isomer and liquid scintillation counting. Although the dialysis concentration factor remained relatively low throughout the experiment, a significant relationship was found between the bioavailability of polychlorinated biphenyl (PCB) and the dissolved organic carbon (DOC) content of the lake water. The availability of PCB was raised by acid and lime treatment for lake water with low DOC content, whereas both treatments lowered the availability of PCB in water from lakes with high DOC content, compared to untreated water. The liming of the lake water did result in a significantly higher bioavailability of hexachlorobiphenyl in five of the 10 tested lakes. The acidification of the lake water had a significant effect on the bioavailability of PCB in some, but not all, of the lakes. The uptake of PCB in the hexane was inversely related to the DOC concentration of the water phase. The pH does influence the bioavailability of PCB in aquatic systems with various concentrations of humus.

Effects of sublethal exposure to chlorine on the uptake of polychlorinated biphenyl congeners by rainbow trout, Salmo gairdneri (Richardson)

Chlorine-induced changes in fish gill histopathology and respiration may alter the uptake of co-contaminants which are accumulated by passive diffusion across gill membranes. The effect of chlorine exposure on gill histopathology, respiratory functions, and the uptake of three polychlorinated biphenyl (PCB) congeners by rainbow trout ( Salmo gairdneri) were determined. Trout gill lamellar lesions occurring during a 24-h exposure to 0.04 mg/l chlorine included proliferation of mucous cells, hyperplasia of epithelial cells, clubbed lamellae, and lamellar fusion. These types of pathological changes would be expected to result in increased diffusion distances of the gill membrane and decreased functional gill surface area. Reductions in oxygen and PCB uptake efficiencies measured in concomitant exposures to chlorine and PCBs using a fish metabolic chamber were consistent with the histopathological results. Increases in trout ventilation compensated for the lowered uptake efficiencies. As a result of ventilatory compensation, there was little change in the oxygen consumption or PCB accumulation by trout throughout the exposure to chlorine. Correlations between oxygen and PCB uptake may provide a basis for estimating toxicant uptake using oxygen uptake data as the basis for extrapolation.

In situ determination of PCB congener-specific first order absorption/desorption rate constants using Chironomus tentans larvae (Insecta: Diptera: Chironomidae)

The uptake of polychlorinated biphenyl (PCB) congeners was measured in the larvae of a laboratory-reared chironomid midge, Chironomus tentans, placed in the upper Hudson river, New York during 2 months in 1985. This procedure was investigated as a method for determining water congener concentrations during times of fluctuating PCB levels, and to model uptake of PCBs by river biota. After a 96 h exposure period, total PCB concentrations in the test organisms averaged 6.7 μmgg −1 total PCBs, compared with water concentrations of 67 ng 1 −1 (mean value for both months). Uptake and elimination constants, time to equilibrium and concentration factors were calculated for each of 21 selected congeners. Analysis of PCB congeners in insects harvested at intervals during the 96 h period showed that uptake differs with varying degrees of chlorination relative to water concentrations. At the end of the exposure period, concentration factors ranged from 4000 to over 300,000 times the water concentrations. Differences in the replicate indicate potential problems with this method as a field tool; instead of using all congeners separated in analysis, several individual congeners should be selected for use based on their importance to the river fauna and the consistency with which they are analyzed.

Zooplankton and Fish Accumulate Chlorinated Hydrocarbons from Contaminated Sediments

Polychlorinated biphenyls (PCBs) originating from the sediment were taken up by zooplankton and fish in artificial ponds in the field. PCB uptake in zooplankton was concentration dependent, as levels of the residues in water varied seasonally. Planktivorous fish accumulated the compounds to high levels at high summer concentrations of PCBs in the water, after which elimination was slow. Levels of PCBs in benthic fishes continuously increased during the 1.5-yr study. The results show that chlorinated hydrocarbons deposited in sediments are available to aquatic organisms.

Polychlorinated Biphenyl Uptake and Transport by Lymph and Plasma Components

The uptake and vascular transport of ingested Aroclor 1242, an isomeric mixture of polychlorinated biphenyls (PCB), was investigated in experimental animals. High concentrations of ingested PCB were found in the chylomicron fraction of thoracic duct lymph. When the lymph flow was exteriorized PCB were not subsequently found in the vascular circulation. When lymph was not exteriorized plasma PCB concentrations reached maximal levels 6 hr after ingestion. Less than 1% of total plasma PCB was detected in cellular fractions of blood over a 10-hr period following ingestion. Chylomicrons contained 31% of total plasma PCB 30 min after ingestion, decreasing to less than 6% at 4 hr. A maximum of 10% of plasma PCB at 1 hr, and less than 5% at 6 hr, after ingestion was associated with very low density lipoproteins (VLDL) or low density lipoproteins (LDL). Although PCB enter the vascular circulation with the chylomicron fractions of lymph, delipoproteinated plasma contained 52% of the total PCB in blood collected 30 min after ingestion. This level increased to 78% after 2 hr, and remained constant at about 80% for an additional 8-hr period. High performance liquid chromatographic (HPLC) examinations of delipoproteinated plasma from blood taken 6 hr after PCB ingestion showed elution of greater than 95% of plasma PCB to coincide with the albumin peak. Electrophoretic examinations of delipoproteinated plasma showed the association of PCB with albumin to be noncovalent. The results suggest that apolar PCB are absorbed into intestinal epithelial cells from which they are secreted into the lymphatic drainage sequestered within the apolar core of chylomicrons, that these PCB transit the thoracic duct and enter the vascular circulation within chylomicrons and are metabolized or otherwise released from chylomicrons during hepatic chylomicron clearance, and that resulting PCB or PCB derivatives circulate in association with plasma albumins.

Uptake and retention of 14C-Aroclor 1254 in the amphipod, Gammarus tigrinus, fed contaminated fungus, Fusarium oxysporum.

Food chain transfer of polychlorinated biphenyls (PCBs) was studied by feeding contaminated fungus,Fusarium oxysporum, to the amphipod,Gammarus tigrinus, both isolated from the Hudson River. Apparent distribution coefficients (μg PCB/g dry wt. fungus // μg PCB/g medium) of 1.14–1.33 × 103 were determined when14C-Aroclor 1254 at 0.007 μg/g was added to 4-day old fungal growth for 24 hr. InG. tigrinus fed contaminated fungus, cross-gut PCB assimilation was indicated. Rapid PCB uptake occurred with a constant level achieved between 9 and 24 hr. Over a period of 144 hr, 57% of accumulated PCBs were eliminated. The results suggest that dietary uptake may contribute substantially to PCB levels inGammarus.

Polychlorinated biphenyl dynamics in hudson river striped bass. I. Accumulation in early life history stages

Polychlorinated biphenyl (PCB) burdens in larval striped bass, Morone saxatilis, from the Hudson River estuary and laboratory determinations of PCB accumulation in larval and juvenile striped bass are presented. Hudson River fish contained variable amounts of PCBs, from below detection (0.05 gm/g dry weight) to 7.07 μ/g. More PCBs similar to Aroclor 1254 than Aroclor 1016 were found. Larval and young-of-year fish exposed to [ 14C]Aroclor 1254 ([ 14C]PCB) in water and sorbed to suspended particles and sediments accumulated PCBs at linear rates during the first 24 h of exposure. Larvae exposed in river water accumulated body burdens related to exposure concentrations. Similar accumulation rates and body burdens in larvae exposed in filtered (0.45 μm pore size) river water showed that accumulation resulted from the uptake of dissolved PCB. PCB accumulation in larvae exposed to [ 14C]PCB on suspended particles resulted from uptake of PCB desorbed from particles. PCB burdens in larvae exposed to sediment-sorbed [ 14C]PCB resulted from desorption of sediment-bound PCB and maintenance of solubility equilibrium with the water. The linear relationship between the initial PCB concentration in water and accumulated PCB in fish from each exposure suggested that accumulation resulted from equilibrium partitioning between water and fish. There are indications that PCB burdens in river fish reflect the solubility-equilibrium based accumulation determined in these studies.

PCB Uptake by Five Species of Fish in Lake Michigan, Green Bay of Lake Michigan, and Cayuga Lake, New York

We applied a bioenergetic model to describe uptake of polychlorinated biphenyls (PCBs) by lake trout (Salvelinus namaycush), brown trout (Salmo trutta), lake whitefish (Coregonus clupeaformis), coho salmon (Oncorhynchus kisutch), and chinook salmon (Oncorhynchus tshawytscha) in Lake Michigan; lake trout and lake whitefish in Green Bay of Lake Michigan; and lake trout in Cayuga Lake, New York. The model describes PCB uptake in terms of metabolism, food consumption, size, and growth. Concentrations of PCBs differ significantly among species; for the same species there are large differences among habitats. The pattern of PCB uptake by brown trout is different from that of the other species. Application of the model with uptake and metabolic parameters estimated by Norstrom et al. describes the trend in the brown trout data; to describe uptake for other species we increased the exponent of weight for metabolism γ. An increase in γ changes the shape of the relation between PCB concentration and body weight from asymptotic to non-asymptotic. In all species tested except brown trout, uptake of PCBs was not asymptotic and concentrations did not approach an equilibrium; accumulation of contaminants was first rapid, decreased toward a plateau, and then began a second rapid increase. Simulation studies indicate that differences in PCB concentrations among species and in the same species among different environments result from differences in metabolic parameters, exposure, size, and rate of growth.Key words: PCBs, bioenergetic model, contaminant uptake, toxicology, fish, Great Lakes, salmon, trout, whitefish

Polychlorinated biphenyl uptake and translation by Spartina alterniflora loisel

This paper presents the findings of initial investigation of the role of Spartina alterniora Loisel. in the movement of chlorinated hydrocarbons. 14C-polychlorinated biphenyls and technical Aroclor® 1254 were used for the determinations. The findings demonstrate that Spartina accumulates 14C-radioactivity from sand and organic mud soil systems treated with 14C-PCB's. These findings also demonstrate that this plant has the capacity to accumulate 14C-radioactivity to levels elevated above that in the treated soil. Other experiments with Aroclor® 1254 demonstrate that cogeners of Aroclor® 1254 are present in Spartina stem and root extracts. These experiments also suggest that the chlorinated hydrocarbon uptake process is modulated by the plant and that this results in selective cogener uptake. The selectivity appears to be for the lesser chlorinated components of the commercial mixture. Overall, this study suggests that Spartina may act as an initial vector for mobilization of sediment bound chlorinated hydrocarbons to the estuarine food chain.

Testicular abnormalities in cod (Gadus morhua) fed Aroclor 1254.

Cod were fed herring containing Aroclor 1254, a polychlorinated biphenyl (PCB), at diet levels of 0, 1, 5, 10, 25, and 50 microgram/g for a period of 5 1/2 months. Histological examinations of the gonads of surviving male fish revealed various testicular abnormalities in 9 of 17 PCB-fed fish but in none of four experimental control and four stock control fish. The abnormalities were observed in testes that were either at functional maturity or in a stage of rapid spermatogenic proliferation but not in testes that were sexually immature or regressed. The testicular abnormalities included disorganization of lobules and spermatogenic elements, inhibition of spermatogenesis, fibrosis of lobule walls, fatty necrosis, and, in one case, total disintegration of the elements in many lobules. There was a significant uptake of PCB by testicular and liver tissues of fish that were fed the higher levels (greater than 1 microgram/g) of Aroclor 1254.

Polychlorinated biphenyls: Accumulation from contaminated sediments and water by the polychaete Nereis diversicolor

Comparisons were made of the accumulation of a polychlorinated biphenyl (PCB) mixture from sediments and from water by the benthic worm Nereis diversicolor. Uptake from sediments was dose-dependent, attaining equilibrium concentration factors of approximately 3 to 4 after 2 months. Subsequent PCB elimination rates were concentration-dependent, with higher initial loss rates evident in the worms containing higher levels of PCBs. Accumulation of PCBs from water was much more rapid; concentration factors reached approximately 800 after only 2 weeks. Estimates were made of the relative importance of sediments and water as a source of PCBs to worms exposed to these contaminants in the natural environment. Calculations based on experimentally derived PCB concentration factors and ambient PCB levels in sediments and water suggest that compared to water, sediments contribute the bulk of these compounds to the worms. The possible mechanisms involved in the uptake of sediment-associated PCBs are discussed.