Bioaccumulation Of Polychlorinated Biphenyls Research Articles

A River-wide Survey of Polychlorinated Biphenyls (PCBs), Polycylic Aromatic Hydrocarbons (PAHs), and Selected Organochlorine Pesticide Residues in Sediments of the Detroit River—1999

The spatial distribution of hydrophobic organic contaminants, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and octachlorostyrene (OCS) in sediments of the Detroit River was established using data from a 1999 river-wide survey. The survey employed a stratified random sampling design that divided the river into six geostatistical zones consisting of upper, middle, and lower U.S. and equivalent Canadian river reaches. Organic carbon normalized OCS sediment concentrations demonstrated no significant differences between U.S. or Canadian sediments or upstream/downstream gradients suggesting that OCS is derived primarily from sources upstream of the Detroit River. In contrast, sum PCBs and sum PAHs were significantly elevated at U.S. as compared to Canadian stations and demonstrated significant increasing upstream/downstream gradients in organic carbon normalized sediment contamination. The upper and middle U.S. river reaches contained a number of near-shore stations with high localized PCB and PAH sediment concentrations suggesting multiple inputs along the upper U.S. portion of the river. Consistent with past surveys, wide-spread sediment contamination of PCBs and PAHs continues to be observed in the highly industrialized Trenton Channel and downstream of Grosse Isle. Threshold effect level (TEL) sediment quality guidelines for PAHs and PCBs were exceeded in 92.6 and 77.8%, respectively, of stations in Trenton Channel and downstream of Grosse Isle. This large reservoir of degraded sediments in the lower U.S. river reach has the potential to enter Lake Erie during sediment disturbance events and likely contributes to gentoxic stress and increased bioaccumulation of PCBs in resident benthos, fish, and wildlife.

Modeling the bioconcentration factors and bioaccumulation factors of polychlorinated biphenyls with posetic quantitative super-structure/activity relationships (QSSAR)

During bioconcentration, chemical pollutants from water are absorbed by aquatic animals via the skin or a respiratory surface, while the entry routes of chemicals during bioaccumulation are both directly from the environment (skin or a respiratory surface) and indirectly from food. The bioconcentration factor (BCF) and the bioaccumulation factor (BAF) for a particular chemical compound are defined as the ratio of the concentration of a chemical inside an organism to the concentration in the surrounding environment. Because the experimental determination of BAF and BCF is time-consuming and expensive, it is efficacious to develop models to provide reliable activity predictions for a large number of chemical compounds. Polychlorinated biphenyls (PCBs) released from industrial activities are persistent pollutants of the environment that produce widespread contamination of water and soil. PCBs can bioaccumulate in the food chain, constituting a potential source of exposure for the general population. To predict the bioconcentration and bioaccumulation factors for PCBs we make use of the biphenyl substitution-reaction network for the sequential substitution of H-atoms by Cl-atoms. Each PCB structure then occurs as a node of this reaction network, which is some sort of super-structure, turning out mathematically to be a partially ordered set (poset). Rather than dealing with the molecular structure via ordinary QSAR we use only this poset, making different quantitative super-structure/activity relationships (QSSAR). Thence we developed cluster expansion and splinoid QSSARs for PCB bioconcentration and bioaccumulation factors. The predictive ability of the BAF and BCF models generated for 20 data sets (representing different conditions and fish species) was evaluated with the leave-one-out cross-validation, which shows that the splinoid QSSAR (r between 0.903 and 0.935) are better than models computed with the cluster expansion (r between 0.745 and 0.887). The splinoid QSSAR models for BAF and BCF yield predictions for the missing PCBs in the investigated data sets.

Bioaccumulation and trophic transfer of polychlorinated biphenyls by aquatic and terrestrial insects to tree swallows (Tachycineta bicolor)

Insectivorous passerines often bioaccumulate polychlorinated biphenyls (PCBs) via trophic transfer processes. Tree swallows (Tachycineta bicolor) frequently are used for estimating PCB bioaccumulation, yet the focus on specific trophic links between contaminated sediment and bird has been limited. Bioaccumulation of PCBs from sediment to tree swallows was examined with focus on trophic pathways by simultaneously examining PCBs in emergent aquatic and terrestrial insects and gut contents of nestlings. Total PCB concentrations increased from sediment (123.65 +/- 15.93 microg/kg) to tree swallow nestlings (2,827.76 +/- 505.67 microg/kg), with emergent aquatic insects, terrestrial insects, and gut content samples having intermediate concentrations. Biota-sediment accumulation factors (BSAFs) varied among congeners for tree swallow nestlings and for male and female Chironomus spp. For nestlings, the highest BSAF was for the mono-ortho-substituted congener 118. Nestling biomagnification values were similar for gut contents and female Chironomus spp., suggesting this diet item may be the main contributor to the overall PCB transfer to nestlings. However, gut content samples were highly variable and, on a PCB congener pattern basis, may have been influenced by other taxa, such as terrestrial insects. Considering dietary plasticity of many insectivorous birds, the present study suggests that a variety of potential food items should be considered when examining PCB accumulation in insectivorous passerines.

Distributions and Congener Patterns of PCBs in Fish from Major Aquaculture Areas in the Pearl River Delta, South China

ABSTRACT The distribution and concentrations of polychlorinated biphenyls (PCBs) were determined in surface sediments and fish collected from freshwater fishponds in six major aquaculture areas of the Pearl River Delta. The concentrations of total PCBs ranged from 7.32 to 36.2 ng/g (dry weight) in sediments and 5.15 to 226 ng/g (lipid weight) in five species of fish, with higher concentrations in fishponds from two industrialized areas. Feeding habits of fishes played a significant role on the accumulation of PCBs and their homologue patterns in fish tissues, with higher concentrations in muscle and viscera of mandarin fish (Siniperca kneri), and tilapia (Tilapia mossambica) and lower in grass carp (Ctenopharyngodon idellus). In muscle, IUPAC No. 118, 138, 81/87, 153, 180, 52, 49, 99, and 44 congeners were the most dominant out of the 36 congeners measured in the present study. The contents of PCBs in fish cultivated in the Pearl River Delta were rather low when compared with the maximum concentration of total PCBs of 2.0 μg/g (wet weight), imposed by the U.S. Food and Drug Administration edible seafood. However, due to the bioaccumulation and biomagnification nature of PCBs through the food chain, continuous monitoring of PCBs as well as other Persistent Organic Pollutants in this rapidly developed region is encouraged.

Tree swallow (Tachycineta bicolor) exposure to polychlorinated biphenyls at the Kalamazoo River superfund site, Michigan, USA

In 1990, a portion of the Kalamazoo River in Michigan, USA, was designated a Superfund site because of the presence of polychlorinated biphenyls (PCBs) in the sediment and floodplain soils. During a four-year period from 2000 to 2003, several avian species were monitored for reproductive effects and concentrations of PCBs in tissues attributed to food chain transfer from contaminated sediments. The tree swallow (Tachycineta bicolor) was chosen as a model receptor for contamination of passerine species. A top-down methodology was used to evaluate the bioaccumulation of PCBs, including non-ortho and mono-ortho congeners, in tree swallow eggs, nestlings, and adults at the Kalamazoo River area of concern (KRAOC) and at an upstream reference site. Generally, a sixfold difference in tissue concentrations of total PCBs was observed between the two sites with concentrations in eggs and nestlings at the KRAOC ranging from 0.95 to 15 microg PCB/g wet weight. Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQsWHO Avian) for PCBs, based on bird-specific World Health Organization toxic equivalence factors, were 10- to 30-fold greater in the KRAOC than at the reference location. Egg and nestling TEQsWHO-Avian ranged from 0.21 to 2.4 ng TEQ/g wet weight at the KRAOC. Hazard quotients calculated from literature-derived toxicity reference values were below 1.0 at both the target and the reference site based on the no-observed-adverse-effect level and the lowest-observed-adverse-effect level.

Sediment influence on congener-specific PCB bioaccumulation by Mytilus edulis: a case study from an intertidal hot spot, Clyde Estuary, UK

An intertidal site in the Clyde Estuary, UK, was selected to evaluate the role of sediment geochemistry on the bioaccumulation of polychlorinated biphenyls (PCBs) by mussels (Mytilus edulis). The area had previously been identified as showing anomalously high levels of PCB contamination (over 1,500 microg kg(-1) total PCB in sediment, 22 congeners). Samples of surface sediment and M. edulis were collected from two closely located sites, one within the anomalous area and another representing typical PCB contamination in the estuary. Sediment samples were separated into grain size fractions and analysed for a range of biomarker compounds, PCBs and sediment mineralogy. The anomalous site showed an atypical association of PCBs with sediment properties, despite both locations showing influence of both petrogenic and pyrogenic organic contamination. Interrogation of data using correlation and principal component analysis showed that sediment mineralogy as well as organic matter composition influenced PCB congener distribution. One sediment source was found to control the PCB concentration in mussels at both locations and clay mineralogy appears to control PCB uptake by biota with preference for higher molecular weight congeners. Overall bioavailability is determined by sediment TOC.

Environmental Monitoring Of Remedial Dredging At The New Bedford Harbor, Ma, Superfund Site

New Bedford Harbor (NBH), MA, is a Superfund site because of high polychlorinated biphenyl (PCB) concentrations in the sediment. From April 1994 to September 1995, a remedial dredging operation (termed the "Hot Spot") removed the most contaminated sediments (PCB concentrations greater than 4000 microg/g) from the upper harbor. During remediation, a monitoring program assessed the potential environmental impacts to NBH and adjacent Buzzards Bay. The monitoring program was developed with input from federal, state, and local authorities. Site-specific decision criteria were established to assess net PCB transport, water column toxicity, and PCB bioaccumulation in blue and ribbed mussels (Mytilus edulis and Geukensia demissa, respectively). The remediation was completed without exceeding PCB net transport or acute toxicity effects specified in the decision criteria. In addition, PCB bioaccumulation in mussels during this time period was not significantly greater than pre- or post-operational measurements. The results indicated that approximately 14000 cubic yards of highly PCB contaminated sediment were permanently removed with minimal environmental effects. The lessons learned during this operation, as well as previous pilot studies at the site, will be used to make full-scale remedial efforts in NBH more efficient and environmentally protective.

Bioaccumulation of PCBs in Burbot (Lota lota L.) After Delivery in Natural Food

Burbot (Lota lota) caught from Lake Päijänne, Central Finland, were exposed under laboratory conditions to four polychlorinated biphenyl (PCB) congeners delivered through diet, and accumulation of congeners to muscle, intestine, gonads, and liver were determined. The selected PCB congeners (PCB18, PCB44, PCB137, and PCB169) were added to intact dead vendace (Coregonus albula) and burbot were fed 5 or 10 contaminated meals (2- and 4-week experiment, respectively). Concentrations of fed congeners were different in the examined tissues. The highest concentrations of all the congeners were found in the livers of burbot. The mean retention efficiencies were 65.0% and 81.7% after 5 and 10 oral doses, respectively. The retention efficiency of the coplanar 169 was lower than those of the other fed congeners. The background organochlorine concentrations of the burbot of this study were compared with the PCB concentrations of burbot caught in the 1970s from Lake Päijänne. These concentrations were compared in order to clarify the PCB load and persistence in a boreal aquatic food web. The total PCB concentration in burbot has not declined during the last decades. The most abundant PCB congeners in the field were PCB138 and PCB153. Residual concentrations of pesticides were also found, especially the DDE, which is a metabolite of DDT.

Effects of dose and particle size on activated carbon treatment to sequester polychlorinated biphenyls and polycyclic aromatic hydrocarbons in marine sediments

Recent laboratory studies show that mixing activated carbon with contaminated sediment reduces the chemical and biological availability of hydrophobic organic contaminants. In this study, we test the effects of varying the activated carbon dose and particle size in reducing the aqueous availability of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) and the uptake of PCBs by two benthic organisms. We mixed PCB- and PAH-contaminated sediment from Hunters Point Naval Shipyard, San Francisco Bay (CA, USA), for one month with activated carbon, at doses of 0.34, 1.7, and 3.4% dry mass basis. We found that increasing the carbon dose increased the effectiveness in reducing PCB bioaccumulation. In 56-d uptake tests with the benthic organisms Neanthes arenaceodentata and Leptocheirus plumulosus, PCB bioaccumulation was reduced by 93 and 90%, respectively, with 3.4% carbon. Increasing the dose also increased the effectiveness in reducing PCB and PAH aqueous concentrations and uptake by semipermeable membrane devices and quiescent flux of PCBs to overlying water. Decreasing activated carbon particle size increased treatment effectiveness in reducing PCB aqueous concentration, and larger-sized activated carbon (400-1,700 microm) was ineffective with a contact period of one month. We invoke a numerical model based on intraparticle diffusion in sediment and activated carbon particles to help interpret our experimental results. This model was useful in explaining the trends for the effect of activated carbon dose and particle size on PCB aqueous concentrations in well-mixed systems.

Lake trophic status and bioaccumulation of polychlorinated biphenyls in benthic organisms: a comparison between littoral and profundal invertebrates

We investigated the influence of lake trophic status on accumulation of polychlorinated biphenyls (PCBs) in littoral and profundal invertebrates from 19 lakes in southern Sweden. The PCB concentration in profundal chironomids (Chironomus sp.) was negatively correlated with lake trophy but the concentration in littoral crayfish (Pacifasticus leniusculus) was unrelated to shifting nutrient regimes. PCB concentrations in chironomids were negatively correlated, while crayfish did not correlate with lake total phosphorus. Two findings indicate that different processes determine bioaccumulation in littoral and profundal invertebrates: (i) a lack of correlation between PCB concentrations in crayfish and chironomids within lakes and (ii) some differences in congener distribution in the two species. We suggest a possible explanation in that chironomids are directly exposed to settling material from the pelagic zone, while crayfish are omnivorous and feed mainly in the littoral zone. A intensive investigation on one pond population could not reveal any individual factors, such as lipid content, size, or sex, influencing bioaccumulation of PCBs in crayfish.

Addition of Activated Carbon to Sediments to Reduce PCB Bioaccumulation by a Polychaete (Neanthes arenaceodentata) and an Amphipod (Leptocheirus plumulosus)

This work examines the effects of adding coke or activated carbon on the bioavailability of polychlorinated biphenyls (PCBs) in contaminated sedimentfrom South Basin at Hunters Point, San Francisco Bay. We show with 28-day sediment exposure tests that PCB bioaccumulation in a polychaete (Neanthes arenaceodentata) is reduced by 82% following 1-month contact of sediment with activated carbon and by 87% following 6-months contact of sediment with activated carbon. PCB bioaccumulation in an amphipod (Leptocheirus plumulosus) is reduced by 70% following 1-month contact of sediment with activated carbon and by 75% after 6-months contact of sediment with activated carbon. Adding coke had a negligible effect on reducing PCB bioaccumulation, probably because of the low specific surface area and the slow kinetics of PCB diffusion intothe solid coke particles. Reductions in congener bioaccumulation with activated carbon were inversely related to congener Kow, suggesting that the efficacy of activated carbon is controlled by the mass-transfer rate of PCBs from sediment and into activated carbon. We find that reductions in aqueous PCB concentrations in equilibrium with the sediment were similar to reductions in PCB bioaccumulation. While no lethality was observed following activated carbon addition, growth rates were reduced by activated carbon for the polychaete, but not for the amphipod, suggesting the need for further study of the potential impacts of activated carbon on exposed communities. The study suggests that treatment of the biologically active layer of contaminated sediments with activated carbon may be a promising in-situ technique for reducing the bioavailability of sediment-associated PCBs and other hydrophobic organic compounds.

Dietary accumulation and metabolism of polybrominated diphenyl ethers by juvenile carp (Cyprinus carpio).

Polybrominated diphenyl ethers (PBDEs) are hydrophobic organic contaminants with properties and nomenclature similar to polychlorinated biphenyls (PCBs). While much information is available on the bioaccumulation and pharamcokinetics of PCBs, little information is available on PBDEs. In this study, juvenile carp were exposed to a diet spiked with a cocktail of four BDE congeners (2,4,4'-tribromoDE [BDE 28], 2,2',4,4'-tetrabromoDE [BDE 47], 2,2',4,4',5-pentabromoDE [BDE 99], and 2,2',4,4',5,5'hexabromoDE [BDE 153]) for 60 d followed by a 40-d depuration period. As a positive control, three PCB congeners with similar log K(ow), values (2,2',5,5'-tetrachlorobiphenyl [PCB 52], 2,2',4,4', 5,5'-hexachlorobiphenyl [PCB 153], and 2,2',3,4,4',5,5'-heptachlorobiphenyl [PCB 180]) were included in the cocktail to compare their assimilation and fate with the model BDE congeners. Concentrations of BDEs and PCBs were monitored in whole-fish tissues and liver tissues over the duration of the experiment. In addition, blood serum samples were taken and pooled among replicates to determine if any phenolic metabolites of BDE and PCBs were formed. Rapid assimilation of BDE 47 was observed relative to all other BDE and PCB congeners, whereas apparently no accumulation of BDE 99 occurred over the course of the experiment. Assimilation efficiencies for BDE 47 suggest that approximately 100% of the BDE 47 exposure was absorbed by carp tissues after 60 d. However, based on the time course of BDE 47 assimilation, it is improbable that all BDE 47 was assimilated; more likely, production of BDE 47 in carp tissues occurred as a result of debromination of higher-brominated compounds, possibly BDE 99. The net assimilation efficiencies of BDE 28 and BDE 153 were also apparently low (20 and 4%, respectively) relative to the three PCBs (40% assimilated) examined in this study. The low assimilation efficiency and high depuration rates for BDEs suggest a higher potential for biotransformation. While all three PCB compounds displayed very similar assimilation and depuration rates, three of the four BDE compounds displayed significantly different assimilation rates among BDE congeners and relative to the PCBs. This study suggests that BDEs have significantly different fate dynamics relative to PCBs in wild carp and likely other species of fish.

Ecological risk assessment of persistent toxic substances for the clam Tapes philipinarum in the Lagoon of Venice, Italy.

Because of contamination of sediments of the Lagoon of Venice, Italy, by inorganic pollutants (e.g., arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc) and organic pollutants (e.g., polychlorobiphenyls), as well as the ecological and economical relevance of the edible clam Tapes philipinarum, an ecological risk assessment was undertaken to ascertain the extent of bioaccumulation that would pose a significant risk. Risk was estimated by means of toxic units and hazard quotient approaches, by comparing the exposure concentration with the effect concentration. Clam exposure was estimated by applying previous results based on bioaccumulation spatial regression models. In addition, a comparison was made between sum of dioxin-like polychlorinated biphenyl (PCB) congeners and total PCB bioaccumulation provided by spatial regression models and by a partitioning model. The effect concentrations were calculated as tissue screening concentrations, as the product of pollutant sediment quality criteria and the bioaccumulation factor. Finally, the cumulative risk posed by selected inorganic pollutants and total PCBs was estimated and a map of risk was drawn. The resulting chemicals of potential ecological concern were mercury, cadmium, arsenic, and nickel, as well as, to a lesser extent, total PCBs.

Comparison of seven indicator PCBs and three coplanar PCBs in beef, pork, and chicken fat

The risk assessment of polychlorinated biphenyls (PCBs) is difficult since complex congeners were used in many industrial applications for a long period of time and the residue monitoring in foods of animal origin and the environment were not established in comparable systems. The relationships of determined concentrations in indicator PCB congeners (mono- and di-ortho PCBs) and coplanar PCB congeners (non-ortho PCBs) in livestock products are presented in this study. The concentrations of seven indicator PCBs were compared with three coplanar PCBs in beef, pork, and chicken fat. Distributions of concentration for the indicator PCBs in three different animal species were similar except for that of PCB-118 (2,3 ′,4,4 ′,5-pentachlorobiphenyl) in pork fat. The congeners with the highest concentration were PCB-138 (2,2 ′,3,4,4 ′,5 ′-hexachlorobiphenyl) in beef and pork fat and PCB-28 (2,4,4 ′-trichlorobiphenyl) in chicken fat. The bioaccumulation and metabolism of PCBs in animal species represent different congener profiles in livestock products. The percentage of the total concentration of three coplanar PCBs was about 2% of the total concentration of the seven indicator PCBs. Relatively high concentration of mono-ortho and di-ortho PCBs in fat samples of livestock products may be calculated with the concentration of coplanar PCBs that can be usually determined on a sequential procedure with dioxin analysis. Therefore, the relationship of the amounts between seven indicator PCBs and three coplanar PCBs may be useful to derive the composition and level of contaminants in beef, pork, and chicken.

Evaluation of polychlorinated biphenyl bioaccumulation patterns in white sea urchins (Lytechinus pictus) using multiple approaches.

The bioaccumulation of polychlorinated biphenyls (PCBs) from three amended field-contaminated sediments (with total PCB concentrations of approximately 4, 10, and 100 microg/g dry wt) by white sea urchins (Lytechinus pictus) was evaluated using multiple statistical and theoretical approaches. Similarity analysis of the PCB bioaccumulation patterns, based on the concept of ecological communities, showed that the PCB patterns in the sea urchins and source sediments were essentially identical for all three sediment concentrations. However, affinity analysis did show some preference for bioaccumulation of higher-molecular-weight and more hydrophobic congeners by the urchins. The affinity analysis also showed that within a homologous series, bioaccumulation increased with increasing hydrophobicity. The biota-sediment accumulation factor (BSAF) profiles for the two lower concentration sediments (A and B) were found to be statistically different from the high concentration sample (sediment C) by a multivariate analysis of variance (MANOVA). The relationship between the measured apparent organic carbon-normalized partition coefficients (K(OC)) and octanol-water partition coefficient (K(OW)) (log based) suggested a significant departure from thermodynamic equilibrium. A nonequilibrium, steady-state bioaccumulation model was found to correctly predict the observed experimental bioaccumulation patterns. To improve the model performance, a hydrophobic term was introduced to account for the drop-off in BSAF profiles with log K(OW) > or = 6.5. This study showed that nonequilibrium, steady-state models are far superior to equilibrium partitioning-based models for understanding the bioaccumulation of organic chemicals by sea urchins.

Content of PCB substances in carrot root and its relations to selected soil factors

The influence of the content of polychlorinated biphenyls (PCB) in agricultural soil and its agrochemical properties on bioaccumulation of PCBs by edible part of carrot (Daucus carota L.) was monitored in 18 locations of the Eastern Slovakian lowland (ESL). The congeners Nos. 28, 52, 101, 138, 153 and 180 have been determined in almost all samples and in both soil and plant material. Soil PCB values varied between 0.16 µg/kg, detected in the congener 52, and 53.4 µg/kg for the congener 180. The average value of the sum of all the followed congeners was 17.9 µg/kg. The variation interval of investigated PCB congeners in carrot root ranged from the level below the detection limit of the analytical method until the maximum of 10.6 µg/kg, for the congener 153. Average amounts of PCBs significantly differed among individual congeners. The average value of the sum of all the followed congeners in carrot root was 5.39 µg/kg. Statistical evaluation of relationships between the concentrations of congeners in carrot root and in soil predominantly showed highly significant dependences. Interestingly, the contents of individual congeners in carrot root were more tightly correlated to the contents of the remaining congeners in the root than to the amount of the analogous congener in the soil. This suggested a possible synergistic effect of PCBs regarding their uptake by the plant. The increasing concentration of inorganic nitrogen in soil leads to an increase of the content of lightly chlorinated congeners in carrot root. Concentrations of lightly chlorinated congeners 28 and 52 were more significantly affected by followed chemical parameters than were concentrations of highly chlorinated congeners. Among the chemical parameters studied [available phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in the soil] only P and K gave statistically significant relationships. Changes in the potassium content were responsible for 7.8% variability in the amount of the congener 28. Similarly, Mg induced 7.6% of alterations in the quantity of the congener 180. Our results suggest that importance of both Ca and Mg concentrations in soil regarding the PCBs uptake were less as compared to the concentration of nitrogen. Statistically significant influence of the humus content in soil varying in range between 0.70 and 8.28% as well as the soil acidity (pH = 4.9–7.3) on the content of some of the investigated congeners in carrot root were not estimated.

Comparing Polybrominated Diphenyl Ether and Polychlorinated Biphenyl Bioaccumulation in a Food Web in Grand Traverse Bay, Lake Michigan

Levels of polybrominated diphenyl ethers (BDEs) in Great Lakes salmonids and ambient air have been recently reported, but few studies worldwide have examined the accumulation of BDEs within aquatic food webs. Here we report some of the first measurements of six BDE congeners that are common components of the pentaBDE commercial mixture within an entire Lake Michigan food web. BDEs were detected in all samples and the dominant BDE congener was 2,2',4,4'-tetrabromodiphenyl ether (BDE 47). BDE 47 levels were consistently greater than those of the 2,2',4,4',5-pentabromodiphenyl ether (BDE 99), despite similar levels of these two compounds in commercial mixtures, suggesting differences in the bioavailability of the BDE congeners or differences in their ability to be metabolized. Additionally, congener composition was significantly different among deepwater sculpin, bloater chub, and lake trout, indicating differences in exposure or differences in biotransformation capacities. Total BDE concentrations in this food web were positively correlated (r = 0.94) with levels of PCBs previously measured in these samples (Stapleton et al. 2001a). Levels of BDE 47 and PCB 153, compounds with similar physicochemical properties, were compared to examine the relative exposure and bioaccumulation of these two classes of chemicals that have different environmental loading histories. Food web magnification factors calculated for these two congeners were 3.2 and 4.0 for BDE 47 and PCB 153, respectively, indicating a comparable potential for biomagnification in food webs.

Differential expression of CYP1A1 mRNA in gill, intestine and liver of tilapia fed with PCB Aroclor-1254 and Aroclor-1260 spiked food

The differential expression of cytochrome P4501A1 gene expression ( CYP1A1) in liver, intestine and gill of juvenile tilapia following oral exposure to polychlorinated biphenyl (PCB) Aroclor-1254 or Aroclor-1260 spiked food were investigated. The fish was fed with 0.1 g/g of body weight each day of the spiked food with a concentration of ∼8 ppm. Fish fed with βNF- or acetone-spiked food were used as positive and negative controls, respectively. On day 1, 3 and 7 of post-treatment, the fish were sampled and analyzed for the total accumulated levels of PCBs, as well as the induced levels of CYP1A1 mRNA. Our results indicated that the fish fed with PCBs-spiked food showed a time-dependent bioaccumulation of PCBs. The time course studies also revealed that in the first 3 days of feeding, significant increases in CYP1A1 were found in intestine (βNF: 320% and Aroclor-1260: 290%), followed by liver (βNF: 144%, Aroclor-1260: 123% and Aroclor-1254: 110%). The transcript levels, then declined slowly. There was no induction of gill CYP1A1 mRNA expression in all treatment groups. Among all the tested tissues, the highest intestinal CYP1A1 transcripts induction has highlighted its prompt response to dietary PCBs exposure. Our study supported the important role of intestine in response to dietary PCBs exposure. In addition, in the present study the relative potency of Aroclor-1260 over Aroclor-1254 in stimulating CYP1A1 expression was discussed, indicating that the highly chlorinated PCBs had a higher potency of bioaccumulation and CYP1A1 mRNA induction.

Toxic effects of polychlorinated biphenyl bio accumulation in sea urchins exposed to contaminated sediments

The uptake patterns and toxicity of polychlorinated biphenyl (PCB) congeners in the white sea urchin, Lytechinus pictus, on exposure to contaminated sediments were investigated. First-order modeling of uptake of the 10 most abundant PCB congeners or domains (containing more than one coeluting congener) by L. pictus indicated that a 35-d exposure was insufficient to reach steady state. Bioaccumulation of PCBs in sea urchins exhibited substantial difference between field and amended sediments, suggesting that caution must be exercised in sample preparation. Some evidence was observed of dependence of measured biota-sediment accumulation factors (BSAFs) on K(ow), indicating that equilibrium partitioning of PCBs may not always be achieved between biota lipid, sediment organic carbon, and water. Survival of L. pictus was unaffected by exposure to field and amended sediments with PCB concentrations varying more than three orders of magnitude. The growth measures (diameter, wt, and gonad wt) were significantly reduced in L. pictus exposed to San Diego Bay ([SDB]; San Diego, CA, USA) sediment, whereas they were relatively unaffected after exposure to amended sediments (with much higher PCB concentrations than SDB sediment) prepared from a New Bedford Harbor (MA, USA) sediment. The toxic effects as measured by the growth rates in L. pictus were likely attributable to polycyclic aromatic hydrocarbons (PAHs), which were elevated in SDB sediment (7.3 microg/g), rather than PCBs.

Bioaccumulation of PCBs and chlorinated pesticides in seals, fishes and invertebrates from the White Sea, Russia

Persistent organochlorines (OC) contaminants, including polychlorinated biphenyl (PCB) congeners, Dichlorophenyltrichloroethane (DDT)- and chlordane (CHL) related compounds, hexachlorocyclohexanes (HCH) isomers and chlorobenzenes (CBz) were determined in blubber of harp seals ( Phoca groenlandica), ringed seals ( Phoca hispida) and bearded seals ( Eringnathus barbatus) as well as in fishes and invertebrates from the White Sea, in northwest Russia. Highest ∑PCB and ∑DDT concentrations were found in samples from two male bearded seals (means of 4150 ng/g lw and 3950 ng/g lw, respectively). Female harp seals had mean ∑PCB and ∑DDT concentrations of 1070±504 ng/g lw and 619±328 ng/g lw, respectively. Male and female adult ringed seals had similar mean ∑PCB concentrations as harp seals (955±385 ng/g lw and 999±304 ng/g lw, respectively). ∑CHL concentrations ranged from 63±29 ng/g lw in blubber of female adult ringed seals, to 322±156 ng/g lw in adult harp seals and averaged 465 ng/g lw in bearded seals. HCH isomers, mirex and chlorobenzenes were detected in all seal samples but were present at lower levels than ∑CHL, ∑DDT and ∑PCB. Concentrations of ∑CHL, ∑DDT and ∑PCB in ringed seals from the White Sea were within the range reported for the Barents Sea but lower than in ringed seals from the Kara Sea. Temporal trends were investigated by comparing concentrations of OCs in blubber of harp seal pups collected in 1992 with pups of the same age collected in 1998. The declines over the 6 year period ranged from approximately 33% for ∑DDT to 60% for ∑PCB. These declines are consistent with reports of declining concentrations ∑DDT in seawater from the White Sea and inflowing rivers in the 1980's and early 1990s. The major OC contaminants in fishes from the White Sea were DDT-related compounds and PCBs. Navaga ( Eleginus navaga) had the highest concentrations of the 5 fish species studied with mean ∑PCB of 41±6 ng/g wet wt. while lowest mean concentrations were present in cod muscle (16±8 ng/g ww). Concentrations of hexachlorobenzene (HCB), DDT, CHL—related compounds and PCB congeners were strongly correlated with trophic level of the organisms assigned using δ 15N values, while β-HCH, γ-HCH and cis-chlordane showed no relationship with trophic level. Food web magnification factors (FWMFs) for p,p′-DDE, α-HCH, oxychlordane and trans-nonachlor the White Sea were similar to those from marine food webs in the Barents Sea and the Canadian arctic, while FWMFs for HCB and PCBs were generally lower. Overall the results suggest that the White Sea marine food differs in terms of the availability of contaminants in comparison to studies of open ocean arctic food webs due to proximity to urban/industrial areas and greater importance of benthic food sources.