Differential accumulation of polychlorinated biphenyl congeners in the aquatic food web at the Kalamazoo River Superfund site, Michigan

Trophic Transfer of Halogenated Organic Pollutants in a Wetland Food Web: Insights from Compound-Specific Nitrogen Isotope of Amino Acids and Food Source Analysis

A trophic position (TP) model (TPmix model) that simultaneously considered trophic discrimination factor and βGlu/Phe variations was developed in this study and was first applied to investigate the trophic transfer of halogenated organic pollutants (HOPs) in wetland food webs. The TPmix model characterized the structure of the wetland food web more accurately and significantly improved the reliability of TMF compared to the TPbulk, TPAAs, and TPsimmr models, which were calculated based on the methods of stable nitrogen isotope analysis of bulk, traditional AAs-N-CSIA, and weighted βGlu/Phe, respectively. Food source analysis revealed three interlocking food webs (kingfisher, crab, and frogs) in this wetland. The highest HOP biomagnification capacities (TMFmix) were found in the kingfisher food web (0.24-82.0), followed by the frog (0.08-34.0) and crab (0.56-11.7) food webs. The parabolic trends of TMFmix across combinations of log KOW in the frog food web were distinct from those of aquatic food webs (kingfisher and crab), which may be related to differences in food web composition and HOP bioaccumulation behaviors between aquatic and terrestrial organisms. This study provides a new tool to accurately study the trophic transfer of contaminants in wetlands and terrestrial food webs with diverse species and complex feeding relationships.

Polychlorinated biphenyls are still alarming persistent organic pollutants in marine-origin animal feed (fishmeal)

The presence of polychlorinated biphenyls (PCBs) in feed materials has caused great public concern because PCBs can accumulate in farmed animals, be transferred farm-to-fork and, ultimately, have a detrimental impact on human health. Recently, the occurrence of PCBs in marine environments has garnered scientific attention due to their high levels and potential reproductive threats to marine apex predators. Fishmeal is marine-origin feed material and is susceptible to PCB contamination from the aquatic trophic chain. The present study collected 102 fishmeal samples during 2012-2017 from major global fishmeal production areas (United States, Europe, China, South America and Southeast Asia). The levels of PCBs (26 congeners) were between 0.4 and 19.9 ng g^-1 dw (mean: 1.94 ng g^-1 dw), with a 75.3% contribution from indicator PCBs on a weight basis. Together with PCDD/Fs, 4.9% of fishmeal exceeded the maximum levels set by the European Commission for dioxin-like compounds (4.0 pg WHO-TEQ/g). The highest PCB levels were found in fishmeal from the U.S. (6.85 ng g^-1 dw), which was nearly five times higher than the other four sampling areas. No clear time trends were found for PCBs in fishmeal during the sampling period. Predicted PCB concentrations in farmed fish via fishmeal consumption were between 1.24 and 2.76 ng g^-1 dw, which was comparable to PCBs in market fish. When compared to other emerging POPs in the same batches of fishmeal, PCBs were still found to be an alarming class of POPs. Some PCB and PBDE congeners might have similar sources and environmental behaviors.

Catbirds are the New Chickens: High Sensitivity to a Dioxin-like Compound in a Wildlife Species

Dioxins and dioxin-like compounds (DLCs) are highly toxic and persistent global pollutants with extremely large differences in sensitivity across taxonomic groups. The chicken has long been considered uniquely sensitive to DLCs among avian species; but DLC toxicity in nondomesticated birds is largely untested, and the relevance of the chicken as an ecological model is uncertain. New approaches that use genotyping of the AHR1 ligand binding domain to screen for DLC sensitivity among avian species predicted that the gray catbird, a relevant wildlife species, is also highly sensitive. We tested this prediction using egg injections of a dioxin-like PCB (PCB-126) and found that the catbird is at least as sensitive as the chicken to DLCs, based on both embryotoxicity and mRNA induction of phase I metabolizing enzymes (CYP1A4/5). This study is the first to confirm that there are wildlife species as sensitive as the chicken and demonstrates how using predictive genotyping methods and targeted bioassays can focus toxicity assessments on ecologically relevant species.

Riparian spiders as sentinels of polychlorinated biphenyl contamination across heterogeneous aquatic ecosystems

Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems. However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the hypothesis that riparian spiders may be effectively used to track spatial patterns of sediment pollution by polychlorinated biphenyls (PCBs) in aquatic ecosystems with high habitat heterogeneity. The spatial pattern of ΣPCB concentrations in 2 common families of riparian spiders sampled in 2011 to 2013 generally tracked spatial variation in sediment ΣPCBs across all sites within the Manistique River Great Lakes Area of Concern (AOC), a rivermouth ecosystem located on the south shore of the Upper Peninsula, Manistique (MI, USA) that includes harbor, river, backwater, and lake habitats. Sediment ΣPCB concentrations normalized for total organic carbon explained 41% of the variation in lipid-normalized spider ΣPCB concentrations across 11 sites. Furthermore, 2 common riparian spider taxa (Araneidae and Tetragnathidae) were highly correlated (r²  > 0.78) and had similar mean ΣPCB concentrations when averaged across all years. The results indicate that riparian spiders may be useful sentinels of relative PCB availability to aquatic and riparian food webs in heterogeneous aquatic ecosystems like rivermouths where habitat and contaminant variability may make the use of aquatic taxa less effective. Furthermore, the present approach appears robust to heterogeneity in shoreline development and riparian vegetation that support different families of large web-building spiders. Environ Toxicol Chem 2017;36:1278-1286. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

A modeling approach to compare ΣPCB concentrations between congener-specific analyses

Changes in analytical methods over time pose problems for assessing long-term trends in environmental contamination by PCBs. Congener-specific analyses vary widely in the number and identity of the 209 distinct PCB chemical configurations (congeners) that are quantified, leading to inconsistencies among summed PCB concentrations (ΣPCB) reported by different studies. Here, we present a modeling approach using linear regression to compare ΣPCB concentrations derived from different congener-specific analyses measuring different co-eluting groups. The approach can be used to develop a specific conversion model between any 2 sets of congener-specific analytical data from similar samples (similar matrix and geographic origin). We demonstrate the method by developing a conversion model for an example data set that includes data from 2 different analytical methods, a low resolution method quantifying 119 congeners and a high resolution method quantifying all 209 congeners. We used the model to show that the 119-congener set captured most (93%) of the total PCB concentration (i.e., Σ₂₀₉ PCB) in sediment and biological samples. ΣPCB concentrations estimated using the model closely matched measured values (mean relative percent difference = 9.6). General applications of the modeling approach include 1) generating comparable ΣPCB concentrations for samples that were analyzed for different congener sets; and 2) estimating the proportional contribution of different congener sets to ΣPCB. This approach may be especially valuable for enabling comparison of long-term remediation monitoring results even as analytical methods change over time. Integr Environ Assess Manag 2017;13:227-232. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Bioaccumulation of dioxin-like PCBs and PBDEs by detritus-feeding fish in the Rio de la Plata estuary, Argentina

A comparative analysis of bioaccumulation behavior of dioxin-like polychlorinated biphenyls (dlPCBs) and polybrominated biphenyl ethers (PBDEs) was conducted involving simultaneous measurements in settling particles and a detritivorous fish (Sabalo, Prochilodus linneatus) collected in the sewage impacted Buenos Aires coastal area. Focalization of dlPCBs and PBDEs along the detritus food chain is reflected by a 30-40-fold increase of dry weight PBDE and dlPCB concentrations from settling particles to fish (1.8 ± 1.0 to 58 ± 31 and 6.8 ± 3.9 to 281 ± 155 ng g(-1) dry weight (dw), respectively). In this transference, dlPCB congeners presented more conservative patterns than those of PBDEs, basically due to debromination of BDE 99 and 153 to BDE 47 in fish. Lipid/organic carbon-based biota-sediment accumulation factors (BSAFs) ranged between 5 and 20 (7.3 ± 3.0 and 16 ± 8.0 for PBDEs and dlPCBs). Congener-specific BSAF of dlPCBs suggested a lower bioavailability of more planar non-ortho-PCB versus mono-ortho-PCB suggesting higher affinity to organic matter. BSAFs of PBDEs differed markedly among bromine homolog groups, supporting the biotransformation-formation from higher brominated to lighter congeners. The log BSAFs-log K OW relationship of dlPCBs and PBDEs presented a parabolic pattern maximizing at log K OW 6-7, but PBDE curve differs reflecting biotransformation processes.

Evaluation and interconversion of various indicator PCB schemes for ∑PCB and dioxin-like PCB toxic equivalent levels in fish

Polychlorinated biphenyls (PCBs) remain chemicals of concern more than three decades after the ban on their production. Technical mixture-based total PCB measurements are unreliable due to weathering and degradation, while detailed full congener specific measurements can be time-consuming and costly for large studies. Measurements using a subset of indicator PCBs (iPCBs) have been considered appropriate; however, inclusion of different PCB congeners in various iPCB schemes makes it challenging to readily compare data. Here, using an extensive data set, we examine the performance of existing iPCB3 (PCB 138, 153, and 180), iPCB6 (iPCB3 plus 28, 52, and 101) and iPCB7 (iPCB6 plus 118) schemes, and new iPCB schemes in estimating total of PCB congeners (∑PCB) and dioxin-like PCB toxic equivalent (dlPCB-TEQ) concentrations in sport fish fillets and the whole body of juvenile fish. The coefficients of determination (R(2)) for regressions conducted using logarithmically transformed data suggest that inclusion of an increased number of PCBs in an iPCB improves relationship with ∑PCB but not dlPCB-TEQs. Overall, novel iPCB3 (PCB 95, 118, and 153), iPCB4 (iPCB3 plus 138) and iPCB5 (iPCB4 plus 110) presented in this study and existing iPCB6 and iPCB7 are the most optimal indicators, while the current iPCB3 should be avoided. Measurement of ∑PCB based on a more detailed analysis (50+ congeners) is also overall a good approach for assessing PCB contamination and to track PCB origin in fish. Relationships among the existing and new iPCB schemes have been presented to facilitate their interconversion. The iPCB6 equiv levels for the 6.5 and 10 pg/g benchmarks of dlPCB-TEQ05 are about 50 and 120 ng/g ww, respectively, which are lower than the corresponding iPCB6 limits of 125 and 300 ng/g ww set by the European Union.

Amino acid sequence of the AhR1 ligand-binding domain predicts avian sensitivity to dioxin like compounds: in vivo verification in European starlings

Research has demonstrated that the sensitivity of avian species to the embyrotoxic effects of dioxin-like compounds can be predicted by the amino acid identities at two key sites within the ligand-binding domain of the aryl hydrocarbon receptor 1 (AhR1). The domestic chicken (Gallus gallus domesticus) has been established as a highly sensitive species to the toxic effects of dioxin-like compounds. Results from genotyping and in vitro assays predict that the European starling (Sturnus vulgaris) is also highly sensitive to dioxin-like compound toxicity. The objective of the present study was to test that prediction in vivo. To do this, we used egg injections in field nesting starlings with 3,3',4,4',5-pentachlorobiphenyl (PCB-126), a dioxin-like polychlorinated biphenyl. Eggs were dosed with either the vehicle control or 1 of 5 doses (1.4, 7.1, 15.9, 32.1, and 52.9 ng PCB-126/g egg). A dose-dependent increase in embryo mortality occurred, and the median lethal dose (LD50; 95% confidence interval [CI]) was 5.61 (2.33-9.08) ng/g. Hepatic CYP1A4/5 messenger RNA (mRNA) expression in hatchlings also increased in a dose-dependent manner, with CYP1A4 being more induced than CYP1A5. No effect of dose on morphological measures was seen, and we did not observe any overt malformations. These results indicate that, other than the chicken, the European starling is the most sensitive species to the effects of PCB-126 on avian embryo mortality reported to date, which supports the prediction of relative sensitivity to dioxin-like compounds based on amino acid sequence of the AhR1.

Could feeding habit and migratory behaviour be the causes of different toxicological hazard to cetaceans of Gulf of California (Mexico)?

In this work, a suite of diagnostic biomarkers was applied to seven cetacean species to evaluate the role of the feeding habits and migratory behavior in the toxicological status of these species from the Gulf of California, Mexico. We investigate the interspecific differences in cytochrome P450 1A1 and 2B (CYP1A1 and CYP2B, respectively), aryl hydrocarbon receptor and E2F transcription factor 1 and the contaminants levels [organochlorine compounds, polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs)] in four odontocete species (common bottlenose dolphin, long-beaked common dolphin, sperm whale and killer whale) and three mysticete species (blue whale, fin whale, and Bryde's whale) using skin biopsy. Differences in contaminant levels and molecular biomarker responses between the odontocete and mysticete species have been pointed out. The canonical discriminant analysis on principal component analysis factors, performed to reveal clustering variables, shows that odontocete are characterised by the highest levels of lipophilic contaminants compared to the mysticete, with the highest levels of polychlorinated biphenyls, dichlorodiphenyltrichloroethanes and PBDEs detected in killer whale and the lowest levels in Bryde's whale. The biomarker data show interspecific differences amongst the seven species, revealing highest CYP1A and CYP2B protein levels in the mysticete fish-eating species (Bryde's whale). In conclusion, three main factors seem to regulate the biomarker responses in these species: (a) the inductive ability of persistent organic pollutants and PAHs; (b) the different evolutionary process of the two CYPs related to the different feeding habits of the species; (c) the migratory/resident behaviour of the mysticete species in this area.

Relationships between dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like biphenyls (dl-PCBs) congener concentrations in aquatic organisms from Sydney Estuary, Australia and physiology, spatial, seasonality, trophodynamic and life history traits

Over the past few decades, there has been considerable interest in hydrophobic persistent organic pollutants (POPs) and their accumulative properties in aquatic organisms. Several factors, such as environmental concentrations (i.e. in sediment) and physiological characteristics of organisms determine species-specific accumulation patterns of POPs in marine animal tissue. The present study investigated factors that govern species-specific accumulation patterns of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like biphenyls (dl-PCBs) in a food web from Sydney Estuary (Australia). The results indicated that physiological characteristics, i.e. lipid %, spatial, i.e. distance from Homebush Bay (point source of POPs) and life history characteristics of the organisms, such as diet and home range, influence PCDD/F and dl-PCB tissue concentrations to a varying degree. For example, PCDD/F tissue concentrations increased with the presence of detritivorous diet, species with limited home range and close proximity to Homebush Bay. On the other hand, lipid %, piscivorous diet and close proximity to Homebush Bay were the main predictors causing increases in dl-PCB tissue levels. Distance from Homebush Bay was the only predictor affecting both PCDD/F and dl-PCB tissue levels at a similar rate, i.e. decreasing tissue concentrations as the distance increases from Homebush Bay.

Dietary exposure of mink (Mustela vison) to fish from the upper Hudson River, New York, USA: effects on organ mass and pathology

The authors evaluated effects of feeding ranch mink (Mustela vison) diets containing polychlorinated biphenyl (PCB)-contaminated fish from the upper Hudson River (New York, USA) on adult and offspring organ mass and pathology. Diets contained 2.5 to 20% Hudson River fish, providing 0.72 to 6.1 µg ΣPCBs/g feed (4.8-38 pg toxic equivalents [TEQWHO 2005 ]/g feed). Absolute thyroid and adrenal gland masses were increased in adult females and 31-week-old juveniles, respectively, and absolute liver and heart masses were decreased in six-week-old kits exposed to dietary PCBs. Dietary concentrations of 0.72 µg ΣPCBs/g feed (4.8 pg TEQWHO 2005 /g feed) and greater induced mandibular and maxillary squamous epithelial proliferation in adult animals. The dietary concentration of ΣPCBs predicted to result in 20% incidence of the jaw lesion (EC20) was 2.3 µg ΣPCBs/g feed (15 pg TEQWHO 2005 /g feed), and the hepatic concentration was 2.8 µg ΣPCBs/g liver (89 pg TEQWHO 2005 /g liver). The EC20 values were greater than the dietary and hepatic concentrations predicted to result in a 20% increase in kit mortality (LC20) at six weeks of age (0.34 µg ΣPCBs/g feed or 2.6 pg TEQWHO 2005 /g feed and 0.80 µg ΣPCBs/g liver or 13 pg TEQWHO 2005 /g liver). However, the EC20 values reflect exposure of adults to PCBs for approximately six months, and the LC20 values reflect exposure of offspring from conception onward.

Sediment contamination in Lyons Creek East, a tributary of the Niagara River: part I. Assessment of benthic macroinvertebrates

Sediments in Lyons Creek East (Welland, Ontario), a tributary of the Niagara River and part of the Niagara River Area of Concern, which exceed screening-level environmental-quality criteria for multiple contaminants, were assessed for biological impacts using information from multiple lines of evidence. An initial chemical survey indicated the primary contaminants of concern to be polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), zinc, and p,p'-DDE due to frequent exceedences of sediment guidelines. A subsequent study focused on the chemical composition of sediment, status of benthic invertebrate communities, contaminant bioaccumulation in resident benthos, and sediment toxicity to laboratory-exposed organisms. Chemical and biological conditions in the creek were compared with those in reference creeks using both multivariate (cluster analysis and ordination) and univariate (regression) techniques. Sediment PCBs (≤ 19 μg/g), PAHs (≤ 63 μg/g), and Zn (≤ 7969 μg/g) were increased above the sediment-quality guidelines along most of the creek; however, the upper 1.5 km portion of the creek was the most highly contaminated and therefore the main focus for biological study. Although severe toxicity was evident at several locations in the upper creek, resident benthic communities were minimally affected by sediment contamination. The cause of toxicity was likely related to a combination of stressors, including PCBs, PAHs, and metals. Due to its biomagnifiable nature, bioaccumulation focused on PCBs; concentrations in resident macroinvertebrates were ≤ 2 orders of magnitude greater than those found in reference creeks and were above tissue residue guidelines, indicating a potential risk for consumers of benthos. This risk was not limited to the upper 1.5 km where other effects were seen.

Polychlorinated biphenyls and organochlorinated pesticides in birds from a contaminated region in South China: association with trophic level, tissue distribution and risk assessment

PURPOSE

Birds have been used successfully for biomonitoring of the levels and effects of persistent organic pollutants (POPs) in the environments; however, there is exceedingly little data on organochlorinated pesticide (OCPs) and polychlorinated biphenyls (PCBs) residues in bird inhabiting in China. In the present study, we detected the concentrations of PCBs, dichlorodiphenyltrichloroethane and its metabolites (DDTs) and hexachlorocyclohexanes (HCHs) in muscle, liver and kidney of birds that inhabit in an e-waste recycling site. Associated with the stable isotope ratio (δ (15)N), we investigated the effect of trophic level on the body burdens of persistent contaminants in birds. The tissue distributions of contaminants in these birds were examined, and a preliminary risk assessment was also conducted.

MATERIALS AND METHODS

Specimens from eight bird species were collected from Qingyuan County, Guangdong Province, South China. Pectoral muscle, liver and kidney tissues were Soxhlet-extracted and finally dissolved in isooctane. Both PCBs and OCPs were analyzed by gas chromatography-mass spectrometry. The subsamples for nitrogen stable isotope analysis were lyophilized, ground and analyzed by a flash EA 112 series elemental analyzer interfaced with an isotope ration mass spectrometer.

RESULTS AND DISCUSSION

PCBs exhibited the highest concentrations among all target compounds, and a preliminary risk assessment suggested that adverse effects might occur in some birds for its high level. Generally, the concentrations of pollutants in liver and kidney were higher than those in muscle, which was mainly driven by passive diffusion to the 'lipid-compartment'. Significant differences in level of contaminants were obtained among species due to the varieties in dietary composition and habitat. An increasing trend was obtained between concentrations of PCBs and DDTs with trophic levels; however, HCHs exhibited the same level among species.

RECOMMENDATIONS AND PERSPECTIVES

Because of the e-waste recycling activities, the study area has been heavily polluted by PCBs. Studies on the species-specific hazard assessment associated with exposure to PCBs are urgently needed in the study of birds in the area.

PCDD/Fs and dioxin-like PCBs in sediment and biota from the Mondego estuary (Portugal)

The concentrations of 17 polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), and 12 dioxin-like polychlorinated biphenyls (dl-PCBs) were measured in sediment and key species as an initial investigation on PCDD/Fs and dl-PCBs contamination in the Mondego estuary (Portugal). The results demonstrated that the values of the total PCDD/Fs (∑PCDD/Fs) concentrations were considerably lower than those of the sum of dl-PCBs (∑dl-PCBs) in all the studied samples. Regarding the contribution of individual congeners, OCDD was the predominant PCDD/F and the mono-ortho PCB 118 and PCB 105 were the dominant PCBs in the majority of the samples. Our results suggest that PCDD/Fs and PCBs behave quite differently along the aquatic food web: ∑PCDD/Fs concentrations were lower in higher trophic-level organisms with fish presenting a distinct PCDD/Fs congeners profile; on the contrary, the higher ∑dl-PCBs values were found in upper-level biota, although not exclusively, and quite similar dl-PCBs congener profiles were observed in nearly all the studied species.

Dietary exposure of three passerine species to PCDD/DFs from the Chippewa, Tittabawassee, and Saginaw River floodplains, Midland, Michigan, USA

Dietary exposure of house wrens (Troglodytes aedon), tree swallows (Tachycineta bicolor), and eastern bluebirds (Sialia sialis) to polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) near Midland, Michigan (USA) was evaluated based on site-specific data, including concentrations of residues in bolus samples and individual invertebrate orders and dietary compositions by study species. Site-specific dietary compositions for the three species were similar to those reported in the literature, but differed in their relative proportions of some dietary items. Oligocheata (non-depurated) and Brachycera (Diptera) contained the greatest average concentrations of ΣPCDD/DFs of the major site-specific dietary items collected via food web-based sampling. Average ingestion values of ΣPCDD/DFs from site-specific bolus-based and food web-based dietary concentrations for nestlings at study areas (SAs) were 6- to 20-fold and 2- to 9-fold greater than at proximally located reference areas (RAs), respectively. Average ingestion values of total 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ(WHO - Avian)) from site-specific bolus-based and food web-based dietary concentrations for nestlings at SAs were 31- to 121-fold and 9- to 64-fold greater than at proximally located RAs, respectively. Estimates of ΣPCDD/DFs and TEQ(WHO - Avian) tissue concentrations based on nestling dietary exposures were greater than those measured. Plausible explanations include nestling metabolism of 2,3,7,8-tetrachlorodibenzofuran and assimilation rates of less than the 70% assumed to occur over the nestling growth period. Profiles of the relative concentrations of individual PCDD/DF congeners in samples of invertebrates and bolus at SAs on the Tittabawassee River downstream of the source of contamination were dominated by 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (22% to 44%) and 2,3,7,8-tetrachlorodibenzofuran (18% to 50%).

Bioaccumulation of polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in fishes from the Tittabawassee and Saginaw Rivers, Michigan, USA

Characterizing biological factors associated with species-specific accumulation of contaminants is one of the major focuses in ecotoxicology and environmental chemistry studies. In this study, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and non- and mono-ortho-substituted polychlorinated biphenyl (PCB) congeners were analyzed in various fish species from the Tittabawassee and Saginaw Rivers (12 fish species; n=314 individuals), Michigan, USA. Due to their migratory habits, greater delta(13)C stable isotope values were found in walleye and white sucker among 12 fish species. Meanwhile, the delta(15)N values indicated that the trophic status was least in carp and greatest in largemouth bass. The greatest total concentrations of dioxins were found in fishes with the lowest trophic status (carp (n=50) followed by channel catfish (n=49)), and concentrations of SigmaPCDD/Fs (20-440pg/g ww (wet weight)), SigmaPCBs (16-690ng/g ww), and TEQs (6.8-350pg/g ww) in carp were also greater than the least mean concentrations in other fishes. Contributions of various biological factors to the species accumulation were assessed. Body weight and lipid content were found to be the most significant factors influencing accumulation of SigmaPCDD/Fs. Lipid content and trophic level seemed to be dominant factors determining accumulation of SigmaPCB and TEQs, but negative correlations between trophic status and concentrations of SigmaPCBs and TEQs were observed possibly due to the great concentrations in benthivorous fishes such as carp occupying lower trophic levels. These factors can be used to predict the contaminant levels of dioxins and health risks of the fishes in the river ecosystem.

Correlations between dioxin-like and indicators PCBs: potential consequences for environmental studies involving fish or sediment

Among the numerous PCB congeners, most of the dioxin-like PCBs (DL-PCBs) need to be characterized by hyphenated techniques. It has been shown in several instances that these congeners are well related to the total PCB content in fish. We examined datasets collected mainly in France, on freshwater and marine fish and sediments. A statistical model linking DL- and indicator PCBs was developed for a dataset composed of freshwater fishes, and proved to predict well DL-PCBs from indicator PCBs in all other fish sets, including marine ones. Type II error rates remained low in almost all fish sets. A similar correlation was observed in sediments. Non-dioxin-like PCBs elicit various adverse effects and represent 95% of the total PCBs. A European guideline for them is needed; the correlation between DL- and indicator PCBs could help develop this standard in the future.

PCBs and DDE in tree swallow (Tachycineta bicolor) eggs and nestlings from an estuarine PCB superfund site, New Bedford Harbor, MA, U.S.A

While breeding tree swallows (Tachycineta bicolor) have been used as biomonitors for freshwater sites, we report the first use of this species to assess contaminant bioaccumulation from estuarine breeding grounds into these aerial insectivores. Eggs and nestlings were collected from nest boxes in a polychlorinated biphenyl (PCB) contaminated estuary, the New Bedford Harbor Superfund site (NBH, Massachusetts, USA), and a reference salt marsh, Fox Hill (FH, Jamestown, Rhode Island, USA). Sediments, eggs, and nestlings were compared on a ng g(-1) wet weight basis for total PCBs and DDE (1,1-bis-(4-chlorophenyl)-2,2-dichloroethene), metabolite of DDT (1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane). NBH samples contained high concentrations of PCBs compared to FH for sediment (36,500 and 0.2), eggs (11,200 and 323), and nestlings (16,800 and 26). PCB homologue patterns linked tree swallow contamination to NBH sediment. NBH samples were also contaminated with DDE compared to FH for sediment (207 and 0.9) and nestlings (235 and 30) but not for eggs (526 and 488), suggesting both NBH and nonbreeding ground sources for DDE. The relationships between sediment and tree swallow egg and nestling PCBs were similar to those reported for freshwater sites. Like some highly contaminated freshwater sites, NBH PCB bioaccumulation had little apparent effect on reproductive success.

Polychlorinated biphenyls and organochlorine pesticides in various bird species from northern China

Little data are available on organochlorine contamination in Chinese terrestrial birds of prey. This study examined the presence of PCBs, DDTs and other organochlorine pesticides in various raptors from northern China. DDE exhibited the highest concentrations among targeted compounds. Greatest levels (23.5-1020 mg/kg lipid weight) were observed in Eurasian sparrowhawks. This may be due to their stopover in southeastern China, where high DDT and dicofol applications have been documented. Residential kestrels exhibited much lower DDE, but similar PCB and HCH concentrations. SigmaTEQs and PCB-126/-77 concentration ratios exhibited significant positive correlations with SigmaPCB concentrations, respectively. Similar results were also demonstrated by a meta-analysis of previously published data across avian species. Possible hepatic sequestration of coplanar PCB-77, -126, -169 and -118 was observed as liver TEQs increased in Eurasian sparrowhawks. These observations may indicate an induction of CYP1A enzymes, as a result of elevated contamination in some species.

Bioaccumulation of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in wild aquatic species from an electronic waste (e-waste) recycling site in South China

Water and several wild aquatic species including Chinese mysterysnail, prawn, fish, and water snake were collected from a reservoir surrounded by several e-waste recycling workshops in South China. The samples were examined to investigate the levels and bioaccumulation extent of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) released from electronic waste (e-waste) which was processed by crude recycling method. Elevated levels of PBDEs [52.7 to 1702 ng/g wet weight (ww)] and PCBs (20.2-25958 ng/g ww) were found in the collected biota species compared to that in the reference samples (13.0-20.5 ng/g ww for PBDEs and 75.4-82.8 ng/g ww for PCBs). log BAF (bioaccumulation factor) ranged from 2.9 to 5.3 for PBDEs and from 1.2 to 8.4 for PCBs, depending on congeners and species. The relationship between log BAFs and log K(OW) (octanol-water partition coefficient) can be adequately described by species-specific parabolic models wherein log BAFs generally increased at log K(OW)<7 then decreased with further increasing log K(OW) both for PBDEs and PCBs. The exceptions were for Chinese mysterysnail and prawn, in which the log BAFs showed a positive linear correlation with log K(OW) for PBDEs. Some PBDE and PCB congeners showed BAF values declining from the general trend predicted by K(OW), largely attributing to metabolism of these congeners in species sampled.

Influence of trophic position and spatial location on polychlorinated biphenyl (PCB) bioaccumulation in a stream food web

We tested the ability of delta15N-derived trophic position (TP) to predict polychlorinated biphenyl (PCB) concentrations in a historically contaminated stream (Twelvemile Creek, SC). We analyzed sediment, four types of organic matter, 27 macroinvertebrate taxa, and 25 fish species from six sites spanning 25 stream km. SigmaPCBs were high across sites (mean fish = 2505 ng g(-1) wet), with little spatial variation in concentrations within a trophic level. SigmaPCBs (wet weight) were significantly positively correlated with TP (r2 = 0.56) and lipids (r2 = 0.44), and concentrations increased 1-2 orders of magnitude among trophic levels. After adjusting for lipids, we calculated a food web magnification factor of 1.6 for SigmaPCBs, which is low compared to marine and lentic food webs. The predictive power of TP for individual congeners increased with Kow (octanol-water partition coefficient), with regression slope approximately 0.48 and r2 approximately 0.70 for Kow > 6.5. The proportion of high Kow compounds increased with distance from the source and with trophic position. Spatial variation in congener patterns was high, in contrast to marine and lentic systems where variation is typically low.

Tilapia larvae Aroclor 1254 exposure: effects on gonads and circulating thyroid hormones during adulthood

Aroclor 1254 a polychlorinated biphenyls (PCBs) mixture, when administrated through the diet, was previously found to inhibit adult tilapia (Oreochromis niloticus) reproduction. Since fish larvae can be more sensitive to contaminants, the objectives of this study were to evaluate in adults the impact in gonad development and in thyroid function of Aroclor 1254 administrated at larvae stages. Aroclor 1254 exposed tilapia presented both ovary and testicular alterations and a decline in T4 plasma concentration while T3 remained unaltered. This work shows exposure to Aroclor 1254 during tilapia early life stages causes a disruption of the reproductive axis that enables reproduction.

PCB congener profiles in nestling tree swallows and their insect prey

Tree swallows (Tachycineta bicolor) are widely used as indicators of local polychlorinated biphenyl (PCB) contamination in North America. Although determining total PCB residues in tissues is useful in environmental monitoring, analysis of PCB congener profiles may reveal sources of contamination and thus prove to be a more refined tool to track contaminants through the food web. To show how differences in PCB congener patterns in birds can be linked to the PCB patterns in their prey, we evaluated PCB congeners in tissues of tree swallow nestlings and their insect prey using principal component analysis and Euclidean similarities. The PC1 scores for PCB residues in nestlings fell between those of the Hexagenia (Ephemeroptera, mayflies) and Chironomidae (Diptera, midges), the two major prey groups of the nestlings. The congener pattern was not related to the location of nest boxes within the study area. However, Hexagenia insects and the nestlings that consumed them were richer in less chlorinated congeners and had higher PC1 scores than Chironomidae insect. In concordance, congener pattern of nestlings that hatched earlier and consumed more mayflies was more similar than that of other nestling to the pattern of nestings texagenia as calculated by Euclidean similarities. We point to the importance of understanding the seasonal availability of specific types of insect prey and their PCB congener pattern before these data are applied in models of trophic transfer of individual PCB congeners within a food web.