PCB and PBDE levels in wild common carp (Cyprinus carpio) from eastern Lake Erie

Twenty years later: PBDEs in fish from U.S. sites with historically extreme contamination

Shortly after their production ban PBDE environmental levels retreated from their peak (circa 2000), but rates of decrease appear to be slowing. Therefore, to update environmental PBDE trends, this study re-examined a U.S. riverine system found in 1999 to have the highest PBDE fish tissue (fillet) burdens in the world. Archived 2018-2020 fish tissues were analyzed for PBDEs and results compared to 1999-2000 and 2007 levels. On a positive note, levels decreased by >75% over 20 years. However, PBDEs were still detectable at each collection site (n = 16) and in 93% of the samples. The highest PBDE level (16,300 ng g-1 lipid weight) was observed in fish from the Dan R., downstream from the Hyco R. (where the world's highest level was previously reported). Levels within Hyco R. fish have declined at an annual rate of 30% through 2007. However, reductions during the subsequent 12 years have diminished to only 1.2%. Fillet levels since 2007 actually increased at an estimated annual rate of 8% immediately downstream from the Hyco R. Congener profiles varied between species, likely due to hepatic enzyme debromination, indicating single congener-based health risk evaluations may not be sufficiently protective. Within North America, PBDE fish levels in this freshwater system were twice those of North America's Great Lakes and exceeded by 10-fold those in carp examined from Illinois, USA., another historical hotspot. Average fish PBDE levels also exceed maxima observed in European and Asian riverine systems and were 1000's of times higher than the environmental quality standard (EQS) set by European Parliament (0.0085 ng g-1 wet weight, aquatic biota). Therefore, to protect human health and the environment, PBDE monitoring should remain a priority for regulatory agencies with the goal to identify and eliminate their source and to consider their potential health impacts in the context of other co-existing (emerging and legacy) contaminants.

Biomonitoring of exposure to Great Lakes contaminants among licensed anglers and Burmese refugees in Western New York: Toxic metals and persistent organic pollutants, 2010-2015

Between 2010 and 2015, the New York State Department of Health (NYSDOH) conducted a biomonitoring program to gather exposure data on Great Lakes contaminants among licensed anglers and Burmese refugees living in western New York who ate locally caught fish. Four hundred and nine adult licensed anglers and 206 adult Burmese refugees participated in this program. Participants provided blood and urine samples and completed a detailed questionnaire. Herein, we present blood metal levels (cadmium, lead, and total mercury) and serum persistent organic pollutant concentrations [polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), dichlorodiphenyldichloroethylene (DDE), and trans-nonachlor]. Multiple linear regression was applied to investigate the associations between analyte concentrations and indicators of fish consumption (locally caught fish meals, store-bought fish meals, and consuming fish/shellfish in the past week). Licensed anglers consumed a median of 16 locally caught fish meals and 22 store-bought fish meals while Burmese refugees consumed a median of 106 locally caught fish meals and 104 store-bought fish/shellfish meals in the past year. Compared to the general U.S. adult population, licensed anglers had higher blood lead and mercury levels; and Burmese refuges had higher blood cadmium, lead, and mercury, and higher serum DDE levels. Eating more locally caught fish was associated with higher blood lead, blood mercury, and serum ∑PCBs concentrations among licensed anglers. Licensed anglers and Burmese refugees who reported fish/shellfish consumption in the past week had elevated blood mercury levels compared with those who reported no consumption. Among licensed anglers, eating more store-bought fish meals was also associated with higher blood mercury levels. As part of the program, NYSDOH staff provided fish advisory outreach and education to all participants on ways to reduce their exposures, make healthier choices of fish to eat, and waters to fish from. Overall, our findings on exposure levels and fish consumption provide information to support the development and implementation of exposure reduction public health actions.

Bioaccumulation of PCBs and PBDEs in Fish from a Tropical Lake Chapala, Mexico

Lake Chapala is the largest natural freshwater reservoir in Mexico and the third largest lake in Latin America. Lakes are often considered the final deposit of polluting materials; they can be concentrated in the organisms that inhabit them, the water, and the sediments. The PCBs and PBDEs are environmental pollutants highly studied for their known carcinogenic and mutagenic effects. PCB and PBDE bioaccumulation levels were determined in Chirostoma spp., Cyprinus carpio, and Oreochromis aureus. In addition, we monitored the concentrations of PCBs and PBDEs in sediment and water from Lake Chapala were monitored. Samples were collected during two periods, in October 2018 and May 2019. The samples were analyzed by gas chromatography coupled with mass spectrometry. Two bioaccumulation factors were determined in fish, one in relation to the concentration of PCBs and PBDEs in sediments and the other in relation to the concentration of PCBs and PBDEs in water. The PCB levels were 0.55–3.29 ng/g dry weight (dw) in sediments, 1.43–2.98 ng/mL in water, 0.30–5.31 ng/g dw in Chirostoma spp., 1.06–6.07 ng/g dw in Cyprinus carpio, and 0.55–7.20 ng/g dw in Oreochromis aureus. The levels of PBDEs were 0.17–0.35 ng/g dw in sediments, 0.13–0.32 ng/mL in water, 0.01–0.23 ng/g dw in Chirostoma spp., 0–0.31 ng/g dw in Cyprinus carpio, and 0.1–0.22 ng/g dw in Oreochromis aureus. This study provides information for a better understanding of the movement, global distribution, and bioaccumulation of PCBs and PBDEs. The results show that the fish, water, and sediments of Lake Chapala are potential risks to the biota and the local human population.

Evidence of continued exposure to legacy persistent organic pollutants in threatened migratory common terns nesting in the Great Lakes

Persistent organic pollutants (POPs) accumulate in the food web of the Great Lakes ecosystem, causing concern that these chemicals play a role in the decline of avian species such as colonial-nesting waterbirds. In this study, samples from four life stages of the common tern (Sterna hirundo), a threatened species in New York State, were collected post-mortem in the Buffalo-Niagara region (United States). Brains (n = 26) and livers (n =27) were analyzed for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and the insecticide p,p'-dichlorodiphenyltrichloroethane (DDT) and its two metabolites p,p'-dichlorodiphenyldichloroethylene (DDE) and p,p'-dichlorodiphenyldichloroethane (DDD). Detectable concentrations of PCBs and PBDEs were observed in all samples; concentrations of total PCBs ranged from 5.59 to 2,490 ng/g wet weight (ww), total PBDEs ranged from 1.09 to 494 ng/g ww, and DDE metabolites ranged from 0.56 to 637 ng/g ww. Analysis of the primary food source for terns in the Buffalo-Niagara region, emerald shiners (Notropis atherinoides), revealed that all three classes of POPs had similar contaminant profiles in the fish to those in the brains and livers of tern samples. Overall, small chicks contained greater concentrations of pollutants than medium chicks and juveniles, likely from maternal loading to eggs. These results underline the persistence of these legacy contaminants in the Great Lakes, despite their banning, and their biomagnification in threatened species through food web interactions.

The correlation study between PCBs and δ15N values or FAs in fish collected from Dongting Lake

The toxicity of polychlorinated biphenyls (PCBs) and their transformation have been intensively investigated in recent years. However, the potential mechanisms of biotransformation in a lake food web remain unclear. To explore the correlation between the PCBs and δ¹⁵N values or FAs, six fish species were collected from Dongting Lake, and various tissues were dissected to analyze the δ¹⁵N values, FAs and PCBs. Based on the wet weight (ww), the concentration of ∑PCBs₁₁₅ ranged from 0.04 to 9.77 ng g^-1, and the highest level was found in the gonad of Cyprinus carpio. The toxicity equivalent (TEQ) of PCBs ranged from 0.003 to 2.39 pg g^-1, and the highest level was found in the fat of Silurus asotusy. The PCB levels in fish collected from Dongting Lake were at the low end of the global range. PCB28, 52, 95, 99, 101, 105 110, 118, 138, 153, 155 and 209 were found in all tissues. PCBs were distributed in a tissue-specific and species-specific manner in fish. PCB153 and 138 had a positive correlation with the TEQ in liver, gill, intestine and skin of fish on the basis of lipid weight (lw). Docosahexaenoic acid/eicosapentaenoic acid (DHA/EPA) and polyunsaturated fatty acid/saturated fatty acid (PUFA/SFA) had a positive correlation with some PCB congeners in the intestine. PCB52, ∑tetra-PCBs and Ind-PCBs had a positive correlation with the δ¹⁵N values in liver of fish on the basis of ww. PUFA/SFA and DHA/EPA might be indicators for the transfer of PCB congeners.

Periodic monitoring of persistent organic pollutants and molecular damage in Cyprinus carpio from Büyük Menderes River

Concentrations of persistent organic pollutants (POPs) were quantified in river water and sediment, as well as in the liver and muscle tissues of Cyprinus carpio that were sampled four times in a year at three stations in the Büyük Menderes River (BMR). Potential biomarkers of possible cellular molecular damage, namely lipid peroxidation (LPO) degradation products, protein carbonyls (PCO) and DNA repair product 8-hydroxy-2'-deoxyguanosine (8-OHdG), were analysed. All the targeted pollutants were measurable both in biotic and abiotic samples. Interestingly, the results suggested that there was recent organochlorine pesticide (OCP) input into the river water in the first two sampling periods in all stations in contrast to prohibition, while input of polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs) was not detected. Liver POP concentrations were higher than in muscle, as expected, and were found to decrease from the first to the fourth sampling period in all stations, except PBDEs. Levels of LPO degradation products in the liver and in muscle tissues decreased from the first to the fourth sampling period. This suggests that these markers reflect the lipid damage in respective tissues due to the tissue burden of targeted POPs. Protein carbonyls were the highest in the first sampling period, followed by a dramatic decrease in the second, and then a gradual increase towards the fourth sampling period in all stations. 8-OHdG levels were lower in Sarayköy station in the first sampling period. Among the measured biomarkers, only several LPO degradation products were significantly correlated with OCPs and PCBs in liver tissue.

Statewide surveillance of halogenated flame retardants in fish in Illinois, USA

In order to better understand the exposure of aquatic systems to halogenated flame retardant contaminants, the present study investigated a variety of legacy and emerging flame retardants in common carp and largemouth bass collected from 58 stations across Illinois (United States). The data revealed that polybrominated diphenyl ethers (PBDEs) generally dominated the flame retardant residues in Illinois fish. Concentrations of ΣPBDEs (including all detectable PBDE congeners) ranged from 24.7 to 8270 ng/g lipid weight (median: 135 ng/g lw) in common carp and 15-3870 ng/g lw (median: 360 ng/g lw) in largemouth bass. In addition to PBDEs, Dechlorane analogues (i.e. Dec-603, Dec-604, and Chlordane Plus) were also frequently detected. Median concentrations of ΣDechloranes (including all detected Dechlorane analogues) were 34.4 and 23.3 ng/g lw in common carp and largemouth bass, respectively. Other emerging flame retardants, including tetrabromo-o-chlorotoluene (TBCT), hexabromobenzene (HBBZ), 2-ethylhexyltetrabromobenzoate (EH-TBB), and bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (BEH-TEBP), were also detected in 40-78% of the fish at the monitored stations. Spatial analysis revealed significantly greater PBDE concentrations in fish living in impaired urban streams and lakes compared to those from the impaired agricultural and unimpaired agricultural/urban waters, demonstrating a significant urban influence on PBDE contamination. Future studies and environmental monitoring are recommended to focus on temporal trends of PBDEs and alternative flame retardants, as well as human exposure risks via edible fishes, in the identified Areas of Concern within Illinois.

Bioaccumulation of PCBs in liver tissue of dusky Carcharhinus obscurus, sandbar C. plumbeus and white Carcharodon carcharias sharks from south-eastern Australian waters

Polychlorinated biphenyls (PCBs) are ubiquitous pollutants in the marine environment that are known to accumulate in apex predators such as sharks. Liver samples from dusky Carcharhinus obscurus, sandbar Carcharhinus plumbeus, and white Carcharodon carcharias sharks from south-eastern Australian waters were analysed for the seven indicator PCBs 28, 52, 101, 118, 138, 153 and 180. Median ∑PCBs were significantly higher in white than sandbar sharks (3.35 and 0.36 μg g(-1) lipid, respectively, p=0.05) but there were no significant differences between dusky sharks (1.31 μg g(-1) lipid) and the other two species. Congener concentrations were also significantly higher in white sharks. Significant differences in PCB concentrations between mature and immature dusky (3.78 and 0.76 μg g(-1) lipid, respectively) and sandbar (1.94 and 0.18 μg g(-1) lipid, respectively) sharks indicated that PCB concentrations in these species increased with age/growth. Higher-chlorinated congeners (hexa and heptachlorobiphenyls) dominated results, accounting for ~90% of ∑PCBs.

Polybrominated diphenyl ethers in mussels (Mytilus galloprovincialis) collected from Central Adriatic Sea

One-hundred and thirty-four samples of mussels (Mytilus galloprovincialis) collected along Central Adriatic Sea in 2013 were examined to determine the levels of fifteen congeners of polybrominated diphenyl ethers (PBDEs). The purified samples were analysed by gas-chromatography coupled to tandem mass spectrometry (GC-MS/MS) applying the isotopic dilution. Only four congeners (PBDE 47, PBDE 99, PBDE 49 and PBDE 100) were present above the established limits of quantification with mean concentrations equal to 73, 30, 19 and 18 pg g(-1), respectively. The concentrations of PBDEs (sum) ranged from 27 to 386 pg g(-1), with the highest levels around the coastal area of Ancona town. The here found levels were comparable to those measured in mussels collected along Southern Adriatic Sea.

Review on the occurrence and profiles of polybrominated diphenyl ethers in the Philippines

The environmental occurrence of polybrominated diphenyl ethers (PBDEs) has been a subject of concern for the past decade because they are persistent, bioaccumulative, and toxic. These compounds have been listed as persistent organic pollutants (POPs) by the Stockholm Convention and are expected to disperse in the global environment even after their use and production. While the occurrence of PBDEs has been well characterized in environmental and biological samples from North America, Europe, and some Asian countries (i.e. China, Japan, and Korea), there is a scarcity of available data in developing Asian countries, such as the Philippines. Examination of PBDE contamination in the Philippine environment is particularly important because regulations have only recently been implemented on the production and use of PBDEs in this country. Additionally, the Philippines receives e-waste from Western countries, which is becoming a major source of organic contaminants in the tropical Asian regions. Ultimately, the Philippines may be a hot spot for contributing to on-going global PBDE pollution due to long-range atmospheric transport. This paper presents a review of the available literature on PBDEs in both environmental and biological samples collected from the Philippines. It is also intended to provide an overview on the levels and congener profiles of PBDEs in samples from the Philippines and to compare these data with other Asian countries. New data are presented on PBDE occurrence and congener profiles in fish commonly consumed by Filipinos and in particulate matter samples collected in Metro Manila, the capital of the Philippines. Both studies contribute to the available knowledge of PBDEs in the Philippines. We aim to stress the importance of future studies in countries receiving e-wastes, such as the Philippines, and suggest what future directions might be taken to enhance the available data on the presence of PBDEs in the Philippine environment.

Endocrine disruptor activity of multiple environmental food chain contaminants

Industrial chemicals, antimicrobials, drugs and personal care products have been reported as global pollutants which enter the food chain. Some of them have also been classified as endocrine disruptors based on results of various studies employing a number of in vitro/vivo tests. The present study employed a mammalian reporter gene assay to assess the effects of known and emerging contaminants on estrogen nuclear receptor transactivation. Out of fifty-nine compounds assessed, estrogen receptor agonistic activity was observed for parabens( n = 3), UV filters (n = 6), phthalates (n = 4) and a metabolite, pyrethroids (n = 9) and their metabolites (n = 3). Two compounds were estrogen receptor antagonists while some of the agonists enhanced 17b-estradiol mediated response.This study reports five new compounds (pyrethroids and their metabolites) possessing estrogen agonist activity and highlights for the first time that pyrethroid metabolites are of particular concern showing much greater estrogenic activity than their parent compounds.

Locomotor activity changes on zebrafish larvae with different 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47) embryonic exposure modes

Polybrominated diphenyl ethers (PBDEs) are widely used flame retardants and are banned around the world as potent environmental contaminants. PBDE-47 is the most concerned PBDE with its environmental prevalence and various toxicity characteristics including neurotoxicity. In this paper, we studied larval zebrafish behavioral alterations caused by PBDE-47 neurotoxicity. The light-dark cycle stimulation was used to investigate the locomotor changes of zebrafish larvae at different ages (4-6 day post-fertilization, dpf) after PBDE-47 exposure (5, 50, 500 μg L(-1)). Three exposure modes, namely continuous exposure, early pulse exposure and interval exposure, were adopted to assess and compare the impacts of exposure modes on larval zebrafish locomotion. Our results showed that locomotor effects upon PBDE exposure depended on the specific exposure mode studied. In the early pulse exposure mode, the locomotion of zebrafish larvae did not change significantly at all PBDE-47 concentrations tested. In contrast, for both the continuous exposure and interval exposure modes, the highest dose of PBDE-47 (500 μg L(-1)) elicited pronounced hypoactivity at 5 dpf during dark periods except for the initial one. However, at 6 dpf, hypoactivity was only observed in the continuously exposed zebrafish larvae (to an even higher degree compared to 5 dpf), but not in the interval exposure treatment group. Our results suggested that the conventional, continuous exposure mode might not be enough to evaluate the toxicity of chemicals in the real environments.

A national probabilistic study of polybrominated diphenyl ethers in fish from US lakes and reservoirs

Polybrominated diphenyl ethers (PBDEs) are persistent, bioaccumulative, and toxic chemicals that are present in air, water, soil, sediment, and biota (including fish). Most previous studies of PBDEs in fish were spatially focused on targeted waterbodies. National estimates were developed for PBDEs in fish from lakes and reservoirs of the conterminous US (excluding the Laurentian Great Lakes) using an unequal probability design. Predator (fillet) and bottom-dweller (whole-body) composites were collected during 2003 from 166 lakes selected randomly from the target population of 147,343 lakes. Both composite types comprised nationally representative samples that were extrapolated to the sampled population of 76,559 and 46,190 lakes for predators and bottom dwellers, respectively. Fish were analyzed for 34 individual PBDE congeners and six co-eluting congener pairs representing a total of 46 PBDEs. All samples contained detectable levels of PBDEs, and BDE-47 predominated. The maximum aggregated sums of congeners ranged from 38.3 ng/g (predators) to 125 ng/g (bottom dwellers). Maximum concentrations in fish from this national probabilistic study exceeded those reported from recent targeted studies of US inland lakes, but were lower than those from Great Lakes studies. The probabilistic design allowed the development of cumulative distribution functions to quantify PBDE concentrations versus the cumulative number of US lakes from the sampled population.

Occurrence of halogenated contaminants in inland and coastal fish from Ghana: levels, dietary exposure assessment and human health implications

Fish consumption is known to have several health benefits for humans. However, the accumulation of toxic contaminants, such as PCBs, PBDEs and HBCDs in fish could pose health hazards. These contaminants were measured in tilapia fish species collected from Ghana. Mean levels were PCBs (62 ng/g lw), PBDEs (7.3 ng/g lw) and HBCDs (1.2 ng/g lw) and the predominance of CB-153, CB-138, CB-180, BDE-47 and α-HBCD is in concordance with scientific literature. The congener profiles of PBDEs and PCBs in the fish suggest that sources of Penta- and Deca-BDE technical mixtures as well as technical PCB mixture (Clophen A60) exist in Ghana, while textile operations and associated release of untreated wastewater are likely to be significant sources of HBCDs. Comparison of the results with some reported studies showed moderate contamination in Ghana although Ghana is a developing country in Africa. Concentrations of PCBs measured in all the specimens in this study were below the food safety guidelines issued by the Food and Drug Administration, USA and the European Commission. The calculated hazard index levels of the target contaminants were below the threshold value of one, indicating that the levels of the target contaminants do not seem to constitute a health risk via fish consumption, with regard to PCBs, PBDEs and HBCDs, based on the limited number of samples that was accounted for in this study. However, due to the continuous discharge of untreated effluents, follow up studies are warranted as the consumption of fish is the primary route of human exposure to PCBs. This maiden report on the status of PBDEs and HBCDs in fish from Ghana will contribute to the knowledge about environmental contamination by POPs in a less industrialized region of the world so far sparsely covered in the literature.

Tissue accumulation and species-specific metabolism of technical pentabrominated diphenyl ether (DE-71) in two predator fish

The tissue-specific accumulation and species-specific metabolism of polybrominated diphenyl ethers (PBDEs) in two predator fish species (redtail catfish and oscar fish) feeding on the same prey (tiger barb) that was exposed to technical pentabrominated diphenyl ether (DE-71) in the laboratory were investigated. The trends in the wet-weight tissue concentration of PBDEs in two predatory fish species suggested that the tissue distribution of PBDEs occurs through a series of events involving passive diffusion to the lipid compartment. A comparison of the fugacities of PBDEs in various tissues and in the serum revealed that the liver, gill, and perivisceral adipose tissue readily achieved equilibrium with the serum, but the muscle, kidney, and intestine exhibited the potential to accumulate PBDEs. The lower fugacities of PBDEs in the intestine may have significance in the transportation of PBDEs from prey to predatory fish. No tissue-specific differences in PBDE congener profiles were found, while interspecies differences in PBDE profiles were evident. The difference in profiles between two species could be attributed to species-specific debromination of PBDE. No metabolic debromination of PBDE was observed in redtail catfish, but extensive debromination of PBDEs occurred in oscar fish. Several hydroxylated PBDEs (OH-PBDEs) were detected in serum samples from the two fish species, but no methoxylated PBDEs were found. The similarities in the OH-PBDE congener profile and the ratio of OH-PBDEs to total PBDEs between the two fish species indicated that the hydroxylation of PBDEs might not be species-specific.

Spatial monitoring of organohalogen compounds in surface water and sediments of a rural-urban river basin in Tanzania

The presence of persistent organic pollutants in Tanzanian environment is not well monitored despite the existing pollution potential from a number of sources. In this study, we investigated for the first time, the concentration profiles of different organohalogen compounds such as organochlorine pesticide residues (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in environmental samples (water and sediments) from the Pangani river basin (PRB). The PRB is one of the largest drainage basins in Tanzania, with its watershed exposed to multiple input sources of trace organic contaminants. Surface water and sediments were sampled from 12 representative stations of diverse characteristics and land-use practices, in three distinct seasons, and extracted by liquid-liquid and Soxhlet extraction methods, respectively. Water samples were analyzed by GC-ECD for OCPs only, while sediment samples were analyzed for OCPs, PCBs and PBDEs by GC/MS. Seven compounds, dominated by HCH isomers (510-4,460 pg/L) and DDT analogs (160-1,460 pg/L),were detected in the water samples. These concentrations are far below the WHO guidelines for drinking water quality. A total of 42 compounds (8 OCPs, 28 PCB congeners and 6 PBDE congeners) were detected in the sediment samples. Their respective total concentration ranges were 245-10,230; 357-11,000 and 38-2,175 pg/g dry weight. The spatial distribution patterns and Hierarchical Cluster Analysis reflected the impact of historical agricultural usage in sugarcane plantations (OCPs), and urbanization (PCBs and PBDEs). Risk assessment using sediment quality guidelines indicated no ecotoxicological risks. The results we have found provide preliminary data on levels of the organic contaminants in Pangani river basin as a new insight on the environmental quality of the area.

Primary investigation on contamination pattern of legacy and emerging halogenated organic pollutions in freshwater fish from Liaohe River, Northeast China

Legacy halogenated compounds, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and emerging organo-halogen pollutants such as Dechlorane Plus (DP), were detected in fish from an old industrial region in Northeast China. PCBs and PBDEs were detected in all of the samples, with concentrations ranging from 38.15 to 170.51 ng/g lipid weight, and 9.40-39.69 ng/g lipid weight, respectively. DP was detected in more than 90% of the samples with concentrations ranging from not detected (ND) to 470 pg g/g lipid weight. Compared with similar data in other areas of the world, PCBs, PBDEs and DP in fish from Liaohe River were at medium or low level. An unusually high percentage of PCB-209 was first reported in the fish samples collected from China. Other halogenated pollutions, such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, octachlorostyrene, chlorinated anisole, chlorinated thioanisole, triclosan-methyl, and other pesticides, have also been identified in the fish samples.

Bioaccumulation of polybrominated diphenyl ethers (PBDEs) in flounder (Platichthys flesus) in the southern Baltic Sea

Concentrations of seven polybrominated diphenyl ether (PBDE) congeners were examined in flounder (Platichthys flesus) and sediment in three southern Baltic Sea sites, representing a range of exposure conditions, in order to evaluate spatial differences in PBDE contamination. Additionally, PBDEs were measured in muscle, liver, and gonads of flounder from one of the sites in order to examine inter-tissue distribution. Mean muscle Σ(7)PBDE levels, in the range of 10-21 ng g(-1) lipid, showed inter-site differences attributed to the distance from the Gulf of Gdańsk, and were overall lower than reported earlier in herring, sprat, and salmon. Biota sediment accumulation factors (BSAFs) for Σ(7)PBDE and individual BDE congeners, in the range of 0.5-24.5, were generally consistent with predicted models for persistent hydrophobic halogenated contaminants. Wet weight (wet wt) PBDE levels in muscle and liver, but not in gonads, were related to tissue lipid content and did not correlate with the fish length and weight. These tissues differed in PBDE levels and profiles as a result of varying lipid content and presumably lipid composition and congener-specific physico-chemical properties.

PCB 126 and other dioxin-like PCBs specifically suppress hepatic PEPCK expression via the aryl hydrocarbon receptor

Dioxins and dioxin-like compounds encompass a group of structurally related heterocyclic compounds that bind to and activate the aryl hydrocarbon receptor (AhR). The prototypical dioxin is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a highly toxic industrial byproduct that incites numerous adverse physiological effects. Global commercial production of the structurally similar polychlorinated biphenyls (PCBs), however, commenced early in the 20(th) century and continued for decades; dioxin-like PCBs therefore contribute significantly to total dioxin-associated toxicity. In this study, PCB 126, the most potent dioxin-like PCB, was evaluated with respect to its direct effects on hepatic glucose metabolism using primary mouse hepatocytes. Overnight treatment with PCB 126 reduced hepatic glycogen stores in a dose-dependent manner. Additionally, PCB 126 suppressed forskolin-stimulated gluconeogenesis from lactate. These effects were independent of acute toxicity, as PCB 126 did not increase lactate dehydrogenase release nor affect lipid metabolism or total intracellular ATP. Interestingly, provision of cells with glycerol instead of lactate as the carbon source completely restored hepatic glucose production, indicating specific impairment in the distal arm of gluconeogenesis. In concordance with this finding, PCB 126 blunted the forskolin-stimulated increase in phosphoenolpyruvate carboxykinase (PEPCK) mRNA levels without affecting glucose-6-phosphatase expression. Myricetin, a putative competitive AhR antagonist, reversed the suppression of PEPCK induction by PCB 126. Furthermore, other dioxin-like PCBs demonstrated similar effects on PEPCK expression in parallel with their ability to activate AhR. It therefore appears that AhR activation mediates the suppression of PEPCK expression by dioxin-like PCBs, suggesting a role for these pollutants as disruptors of energy metabolism.

Decabromodiphenyl ether (BDE-209) enters the food web of the River Po and is metabolically debrominated in resident cyprinid fishes

Decabromodiphenyl ether (BDE-209), the primary constituent of a widely used flame retardant formulation, is present at relatively high levels in sediments and macroinvertebrates of the River Po. Since it was demonstrated that BDE-209 can be biotransformed to smaller and more toxic polybrominated dipheyl ethers (PBDEs), the main objective of this study was to assess whether the large quantities of BDE-209 present in the River Po are bioavailable to the higher levels of the food web and are biotransformed in feral fishes. To this aim, 23 cyprinids, mainly common carp, were analysed for the hepatic contents of PBDEs. Contrary to sediments and invertebrates of the same area, no fish sample contained detectable levels of BDE-209. All fishes contained typical PBDE representatives, e.g. BDE-47, BDE-99, BDE-100, BDE-153 and BDE-154, but more importantly they contained three congeners, i.e. BDE-179, BDE-188 and BDE-202, which are not present in any technical formulations and are known products of BDE-209 debromination in fish. The age of carps had no effects on the bioaccumulation of PBDEs. Conversely, the contents of PCBs, which also were determined in the same fish samples, showed a positive correlation with age. Both groups of chemicals displayed a tendency to a higher contamination in male fish. This study shows that BDE-209 enters the food web of the River Po contributing to the load of lower brominated PBDEs and thus to the load of chemical stressors threatening the aquatic life of the major Italian watercourse.

Spatial trends of polybrominated diphenyl ethers in Canadian fish and implications for long-term monitoring

A nationwide study was conducted to examine concentrations of polybrominated diphenyl ethers (PBDEs) in top predatory fish, with a focus on lake trout (Salvelinus namaycush), across Canada, and to explore possible influences of food web processes. Concentrations of the three most abundant PBDE homolog groups (tetra-, penta-, and hexa-PBDEs) were, for the most part, higher in Great Lakes and Lake Champlain fish compared with fish from other systems. The Canadian Federal Environmental Quality Guideline for the penta-homolog was exceeded in 70% of the fish examined. However, virtually no guideline exceedances were found for other congeners. In general, PBDE-47 (a representative lower brominated congener) was significantly and positively correlated with fish length, weight, age, lipid content, and stable isotopes of nitrogen and carbon. Significant differences in the slopes of the PBDE-47/covariate relationships between sites prevented concentrations from being adjusted using an analysis of covariance (ANCOVA). However, plots showed that elevated concentrations of PBDE-47 in Great Lakes and Lake Champlain fish remained after accounting for the influence of covariates. In contrast, for PBDE-183 (a representative higher brominated congener), the relationships between fish concentrations and covariates were not consistent, which could be a result of biotransformation being more important in controlling its bioaccumulation. The data from the current study show an overall disconnect between fish PBDE concentrations and likely loadings, which may be caused by differences in food web processes between systems. Continued long-term fish contaminant monitoring is needed to evaluate potential risk to fish and their consumers. However, we also recommend sediment sampling and focused food web studies to provide information on PBDE inputs to the systems and mechanisms of biomagnification, respectively.