Accumulation Of Polybrominated Diphenyl Ethers Research Articles

Chlorinated and brominated contaminants including PCBs and PBDEs in minke whales and common dolphins from Korean coastal waters

Information on the occurrence and distribution of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) in marine mammals from Korean coastal waters is not available to date. This is the first study to investigate concentrations and accumulation of PCBs, OCPs, and PBDEs in liver and blubber of minke whales and common dolphins from Korean coastal waters. The concentrations of organochlorines and PBDEs in blubber were several times higher than in liver. The concentrations of PCBs and OCPs were generally low, but the concentrations of PBDEs were similar to those reported for cetaceans elsewhere. The accumulation profiles of OCPs differed between liver and blubber, while the profiles of PCBs and PBDEs were relatively similar in both tissues. The concentrations of PCBs, DDTs, CHLs and PBDEs in common dolphins were significantly higher than those in minke whales, while there were no inter-species differences for HCHs and HCB. The predominant OCP, PCB and PBDE congeners in cetaceans were p, p′-DDE, PCB 153 and BDE 47, respectively. The concentrations of PCBs and DDTs in Korean cetaceans were close to the threshold for adverse health effects.

Mechanism of Polybrominated Diphenyl Ether Uptake into the Liver: PBDE Congeners Are Substrates of Human Hepatic OATP Transporters

Polybrominated diphenyl ethers (PBDEs) are flame-retardants that upon chronic exposure enter the liver where they are biotransformed to potentially toxic metabolites. The mechanism by which PBDEs enter the liver is not known. However, due to their large molecular weights (MWs approximately 485 to 1000 Da), they cannot enter hepatocytes by simple diffusion. Organic anion-transporting polypeptides (OATPs) are responsible for hepatic uptake of a variety of amphipathic compounds of MWs larger than 350 Da. Therefore, in the present study, Chinese hamster ovary cell lines expressing OATP1B1, OATP1B3, and OATP2B1 were used to test the hypothesis that OATPs expressed in human hepatocytes would be responsible for the uptake of PBDE congeners 47, 99, and 153. The results demonstrated that PBDE congeners inhibited OATP1B1- and OATP1B3-mediated uptake of estradiol-17-beta-glucuronide as well as OATP2B1-mediated uptake of estrone-3-sulfate in a concentration-dependent manner. Direct uptake studies confirmed that all three PBDE congeners are substrates for the three tested hepatic OATPs. Detailed kinetic analysis revealed that OATP1B1 transported 2,2',4,4'-tetrabromodiphenyl ether (BDE47) with the highest affinity (K(m) = 0.31 microM) followed by 2,2',4,4',5-pentabromodiphenyl ether (BDE99) (K(m) = 0.91 microM) and 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE153) (K(m) = 1.91 microM). For OATP1B3, the order was the same (BDE47: K(m) = 0.41 microM; BDE99: K(m) = 0.70 microM; BDE153: K(m) = 1.66 microM), while OATP2B1 transported all three congeners with similar affinities (BDE47: K(m) = 0.81 microM; BDE99: K(m) = 0.87 microM; BDE153: K(m) = 0.65 microM). These results clearly suggest that uptake of PBDEs via these OATPs is a mechanism responsible for liver-specific accumulation of PBDEs.

Bioaccumulation and trophic transfer of polybrominated diphenyl ethers (PBDEs) in biota from the Pearl River Estuary, South China

Two hundred and fifty-four biota samples (four species of invertebrates and ten species of fish) were collected from the Pearl River Estuary between 2005 and 2007 and one hundred and twenty four individual or composite samples were analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of PBDEs in organisms varied from 6.2 to 208 ng/g lipid weight. This PBDE level was significantly lower than those collected in 2004, showing a decreasing trend of PBDEs in biota in the study area. Trophic magnification factors (TMFs) for nine BDE congeners were calculated with values ranging from 0.78 to 3.0. TMFs of BDE47, 66, 100, 99, 154, and 153 were statistically greater than one, indicating a biomagnifcation potential for these congeners. Significant positive correlations were also found between concentrations of the total PBDEs, BDE28, 47, 66, 100, 99, 154, and153 and lipid content in biota, indicating the that bioconcentration also played an important role in the accumulation of PBDEs. No correlation between trophic level and lipid content was found, suggesting that biomagnification was not the result of lipid content effect but indeed occurred. The concentration ratios of BDE99 to BDE100 were much lower in biota than that in water implying that potential congener-specific biotransformation of PBDEs occurred and influenced the biomagnification of BDE congeners.

Fate of Polybrominated Diphenyl Ethers during Wastewater Treatment/Polishing and Sludge Stabilization/Disposal

Large quantities of polybrominated diphenyl ethers (PBDEs) have been used as flame retardants in clothing and plastic products since the 1970s. A small fraction of the PBDEs in manufactured products subsequently enters municipal wastewater. Nevertheless, the resistance of these compounds to chemical and biochemical transformations provides opportunities for accumulation in sediments that are in contact with wastewater effluent and agricultural soils that are amended with biosolids derived from wastewater treatment. Balances developed for PBDE congeners indicate that conventional wastewater treatment processes and soil infiltration of treated wastewater in recharge operations do not discriminate significantly among the major congeners in commercially available PBDE products. Accumulation of PBDEs at near part-per-million levels was measured in the surface sediments at the Sweetwater Recharge Facility in Tucson, Arizona, during 10-15 years of operation. Half-lives for loss of major PBDE congeners from sediments were decades or longer. Local agricultural soils amended with biosolids over a 20-year period showed similar accumulation of PBDEs. The widespread use of PBDEs in commercial products, compound persistence, and toxicity indicate that additional effort is warranted to better understand fate-determining processes for PBDEs in the environment.

Levels of polybrominated diphenyl ethers (PBDEs) and organochlorine pollutants in two species of Antarctic fish ( Chionodraco hamatus and Trematomus bernacchii)

In the late 1960s the first scientific studies on contamination in Antarctica demonstrated the presence of pollutants in Antarctic ecosystems. Many Persistent Organic Pollutants (POPs) are transported globally from the areas in which they are produced and released into the environment in remote areas, including Antarctica. Here we report results obtained concerning the accumulation of polybrominated diphenyl ethers (PBDEs), mono- and non- ortho-polychlorobiphenyls (PCBs), polychlorodibenzodioxins (PCDDs) and polychlorodibenzofurans (PCDFs) in the tissues of two species of Antarctic fish ( Chionodraco hamatus and Trematomus bernacchii). The 2,3,7,8-TCDD toxic equivalents (TEQs) were also calculated to evaluate the potential risk of these compounds for the two species. In general, POP levels were higher in the tissues of T. bernacchii than in C. hamatus and the highest concentrations were found in the liver of both species. The PBDE levels varied from 160.5 pg g −1 wet wt in C. hamatus muscle to 789.9 pg g −1 wet wt in T. bernacchii liver and were lower than the levels of PCBs. PCBs were the main organochlorine compounds detected and their concentrations ranged from 0.3 ng g −1 wet wt in C. hamatus muscle to 15.1 ng g −1 wet wt in T. bernacchii liver. TEQ concentrations resulted higher in C. hamatus than in T. bernacchii and were due mainly to PCDDs. The presence of PBDEs and organochlorine pollutants in the tissues of Antarctic organisms confirms their global transport and distribution.

Polybrominated diphenyl ethers (PBDEs) in farmed and wild salmon marketed in the Northeastern United States

Recently, we reported on the analysis of polychlorinated biphenyls (PCBs) and chlorinated pesticides in farmed Atlantic salmon ( Salmo salar) from Maine, eastern Canada, and Norway, and wild Alaskan Chinook salmon ( Oncorhynchus tshawytscha). In this paper, we extend the analysis to polybrominated diphenyl ethers (PBDEs) in these samples. Total PBDE concentrations in the farmed salmon (0.4–1.4 ng/g, wet weight, ww) were not significantly different from those in the wild Alaskan Chinook samples (0.4–1.2 ng/g, ww), nor were significant differences found among regions. However, significant intra-regional variations in concentrations of total PBDEs and tetra-BDE 47 were observed in the salmon from the Canadian farms ( p < 0.01). Congener profiles were dominated by BDE-47, followed by the penta-BDEs 99 and 100. PBDE concentrations in the Canadian samples were lower than those reported two years earlier. Removal of skin resulted in no overall reduction in PBDE concentrations in our farmed salmon, and in some cases, PBDE concentrations were higher in skin-off samples. PBDEs were correlated with lipids only in the skinned samples, suggesting that there is greater accumulation and retention of PBDEs in muscle lipids than in skin-associated fat. In skin-on samples, modest correlations were observed between concentrations of PBDEs and PCBs ( R 2 = 0.47) and mono- ortho PCBs ( R 2 = 0.50), whereas PBDEs were not correlated with non- ortho PCBs.

Levels and bioaccumulation of organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) in fishes from the Pearl River estuary and Daya Bay, South China

Fifty fish samples were collected from the Pearl River estuary (PRE) and Daya Bay, South China and were analyzed for DDTs, HCHs, chlordanes and polybrominated biphenyl ethers (PBDEs). Except the high concentrations of DDT observed in fishes, the concentrations of HCHs, chlordanes and PBDEs were low when compared to other regions. BDE-47 was the predominant PBDE congener and the BDE-209 concentrations were relatively low, despite its high concentration in surface sediments. The absence of significant increase of DDT, HCH, chlordane and PBDE concentrations towards higher δ 15N values, as well as the lack of a significant correlation ( p < 0.1) between log concentrations (lipid normalized) and δ 15N, may indicate a weak biomagnification of these chemicals in the food webs. Good agreement was observed between their concentrations and lipid contents of the organisms. Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms in the studied subtropical waters.

Polybrominated diphenyl ethers and persistent organochlorines in Japanese human adipose tissues

The present study determined concentrations of polybrominated diphenyl ethers (PBDEs) and persistent organochlorines (OCs) in Japanese human adipose tissues collected during 2003–2004. Concentrations of PBDEs in adipose tissues were 1–2 orders of magnitude lower than those of OCs. However, observed PBDE congener levels in this study were relatively higher than those in Japanese human adipose tissues collected during 2000 reported previously, while OC levels were comparable to those in specimens collected during 1999 reported by our group. In addition, no age-dependent accumulation of PBDEs was observed, while OC levels except chlordane compounds increased with age. These results indicate recent human exposure to PBDEs in Japan. Among PBDE congeners accumulated in Japanese adipose tissues, BDE-153 was dominant, but this trend was different from those in human milk (BDE-47) and blood (BDE-209) reported previously in Japan, implying the congener-specific kinetics in human bodies. The significant positive correlations between PBDEs and OCs were observed in Japanese adipose tissues, indicating the similar exposure route of these contaminants for Japanese citizens, probably via fish intake.

Modeling Atmospheric Vegetation Uptake of PBDEs Using Field Measurements

Polybrominated diphenyl ethers (PBDEs) are flame retardants used in a variety of consumables. Models indicate that air-vegetation exchange plays an important role in their global distribution. The present study surveyed PBDEs in spruce needles and air (gaseous and particulate-bound) over an annual cycle to model accumulation of PBDEs in vegetation. Air-particulate distributions revealed that penta and higher BDE congeners were mainly associated with particulates even in warmer temperatures, whereas for the tri- and tetra-BDE congeners, a significant temperature dependence was observed. Using measured vegetation and atmospheric concentrations from bud burst 2004 to June 2005, a modeling concept was developed to determine PBDE deposition velocities to vegetation. Particulate-bound deposition velocity was calculated to be 3.8 m/h. Net gaseous transfer velocities ranged from 2.4 to 62.2 m/h and correlated significantly with log K(OA). These derived values were used to model PBDE accumulation by vegetation through time, and these agreed well with measured values. This study provides the necessary background for modeling PBDE transport between air and coniferous vegetation globally.

Geographical distribution of polybrominated diphenyl ethers (PBDEs) and organochlorines in small cetaceans from Asian waters

Polybrominated diphenyl ethers (PBDEs) are one of the flame retardants widely used in plastics, textiles, electronic appliances, and electrical household appliances. In this study, PBDEs and organochlorine compounds (OCs) were determined in the archived samples from the Environmental Specimen Bank for Global Monitoring ( es-BANK) at Ehime University. The blubber of cetaceans found stranded along the coasts of Japan, Hong Kong, the Philippines and India during the period from 1990 to 2001 were employed for chemical analysis to understand the present status of contamination and the specific accumulation of PBDEs. PBDEs were detected in all the cetacean samples analyzed, and concentrations were one or two orders of magnitude lower than for PCBs and DDTs. Concentrations of PBDEs ranged from a low value of 6.0 ng/g lipid wt. in spinner dolphin ( Stenella longirostris) from India to a high value of 6000 ng/g lipid wt. in Indo-Pacific humpback dolphin ( Sousa chinensis) from Hong Kong. No difference in PBDE levels between coastal and offshore species from Japan was observed, implying the existence of pollution sources in this region other than Japan. Highest concentrations of PBDEs were found in animals from Hong Kong, followed by Japan, and much lower levels from the Philippines and India, suggesting that developing nations may also have pollution sources of PBDEs. Geographical distribution of PBDEs in Asian waters was different from PCBs but similar to DDTs.

Polybrominated Diphenyl Ether (PBDE) Effects in Rat Neuronal Cultures: 14C-PBDE Accumulation, Biological Effects, and Structure-Activity Relationships

Polybrominated diphenyl ethers (PBDEs), widely used as flame-retardants, are now recognized as globally distributed pollutants, and are detected in most environmental and biological samples, including human blood, adipose tissue, and breast milk. Due to their wide use in commercial products and their persistent nature, long-term exposure to PBDEs may pose a human health risk, especially to children. Our previous reports showed that the commercial PBDE mixture, DE-71, affected protein kinase C (PKC) and calcium homeostasis in a similar way to those of a structurally-related polychlorinated biphenyl (PCB) mixture. These intracellular signaling events are associated with neuronal development and learning and memory function. The objectives of the present study were to test whether environmentally relevant PBDE congeners, with different position and number of bromines, affected PKC translocation in cerebellar granule neuronal cultures and compare the potency and efficacy of PBDE congeners with their 14C-accumulation. All the tested PBDE congeners increased 3H-phorbol ester (PDBu) binding, and a significant effect was seen as low as 10 microM. Among the congeners tested, 2,2',4,4'-tetrabromodiphenyl ether (PBDE 47) increased 3H-PDBu binding in a concentration-dependent manner and to a greater extent than other congeners. These effects were seen at concentrations and exposure times where no cytotoxicity was observed. The efficacy of PBDE congeners varied with their structural composition, and the effects seen on 3H-PDBu binding with some PBDE congeners are similar to those of PCB congeners. Cerebellar granule neurons accumulated all three PBDE congeners (PBDEs 47, 99, and 153) following exposure. At the lowest concentration (0.67 microM), about 13-18% of the total dose of 14C-PBDE congeners was accumulated by these neurons. There were distinct differences in the pattern of 14C-PBDE accumulation among the PBDE congeners. The 14C-PBDE accumulation, either represented as percent basis or nanomole basis, was much lower for the 30.69 microM PBDE 99 and 10.69-30.69 microM PBDE 153 than at the lower concentrations, which may be due to low solubility of these congeners. The accumulation pattern with PBDE 47 did not vary with concentration. On a nanomole accumulation basis, PBDEs 47, 99, and 153 accumulation was linear with time. While the nanomole accumulation was linear with concentration for PBDE 47, it is nonlinear for PBDEs 99 and 153. The pattern of PBDE accumulation seems to correlate with the effects on PKC translocation, with regression values of 0.773-0.991. These results indicate that PBDEs affected PKC translocation in neurons in a similar way to those of other organohalogens, some PBDE congeners are equally efficacious as the respective PCB congeners, and PBDE accumulation correlated well with PKC translocation, suggesting a common mode of action for this group of chemicals.

Congener-specific accumulation and food chain transfer of polybrominated diphenyl ethers in two arctic food chains.

Congener-specific accumulation and prey to predator transfer of 22 polybrominated diphenyl ethers (PBDEs) were assessed in polar cod, ringed seal, polar bear, and beluga whale. Although the concentrations found were relatively low, these results show that PBDEs have reached the Arctic. PBDE congeners 47, 99, and 100 were dominant in all species studied. The pattern in ringed seal was somewhat simpler than in polar cod, with PBDE 47 accounting for more than 90% of the total PBDEs. In contrast, beluga whales, feeding on prey similar to that of ringed seals, showed higher PBDE levels and a more complex PBDE pattern than ringed seals. In contrast, polar bears contained only PBDE 47 in relatively small amounts. These differences in levels and patterns are likely due to species-specific differences in PBDE metabolism and accumulation. The metabolic index suggested that PBDEs 47 and 99 accumulate to the same magnitude as PCB 153 (PCB = polychlorinated biphenyl) in ringed seals and beluga whales. In contrast to beluga whales, ringed seals can metabolize PBDE 100 to some extent. Polar bears are seemingly capable of metabolizing virtually all PBDEs and are therefore unsuitable as indicators for PBDE contamination in the environment.