Coplanar Polychlorinated Biphenyls Congeners Research Articles

Reusable pyrene-based fluorescent organogels for polychlorinated biphenyl detection and removal

Highly toxic hydrophobic polychlorinated biphenyls (PCBs) pollutants are resistant to degradation, and limited methods are available for their elimination, leading to their long-term persistence in ecosystems, which can harm humans and the environment. Therefore, early detection, removal, and continuous monitoring of PCBs are crucial. In this study, a novel fluorescent polymeric probe (P1) to detect PCB congeners (77, 118, and 126) in water was developed. P1 was synthesized by incorporating N,N’-dimethylacrylamide (DMAA) and pyren-1-ylmethyl methacrylate (PyMMA) to form p(DMAA-co-PyMMA). P1 demonstrated high sensitivity toward the most toxic coplanar PCB congeners, 77 and 126, via a fluorescence turn-on mechanism. This sensitivity was attributed to hydrophobic and π–π interactions between the PCBs and PyMMA units of P1. The detection limits for PCB congeners 77 and 126 were determined to be 0.028 and 0.039 mM, respectively. However, PCB 118, a mixed planar congener, exhibited less detection sensitivity than PCB 77 and 126. A porous three-dimensional polymeric organogel (OG) comprising butyl acrylate, PyMMA, and a cross-linker ethylene glycol dimethacrylate was synthesized for practical application. The OG selectively removed PCBs compared to other competing pollutants due to the high hydrophobicity of the PCBs, achieving removal rates of 63 % for PCB 77 and 55 % for PCB 126. The large surface area of the OG facilitated enhanced hydrophobic and π-π interactions between the PCBs and pyrene units. This work emphasizes the efficacy of P1 in detecting PCBs and the potential of using OG in eliminating PCBs, offering a viable method for monitoring and remedying PCB-contaminated environments.

Skeletal toxicity resulting from exposure of growing male rats to coplanar PCB 126 is associated with disruption of calcium homeostasis and the GH-IGF-1 axis and direct effects on bone formation.

Skeletal toxicity has been reported following exposure to polychlorinated biphenyl (PCB) mixtures. However, molecular mechanisms remain poorly understood. We exposed groups of male 4-5-week-old Sprague-Dawley rats to 3,3', 4, 4', 5-pentachlorobiphenyl (PCB 126), a dioxin-like coplanar PCB congener by a single i.p. injection of 5µmol/kg in soy oil vehicle or vehicle alone. After 4weeks, rats were euthanized. PCB exposure resulted in hypocalcemia (P < 0.05) and significant increases in serum PTH without changes in serum phosphorous. Hyperparathyroidism was accompanied by increased expression of mRNAs of vitamin D3 metabolizing cytochrome P450 enzymes CYP27B1 and CYP24 in the kidney (P < 0.05). PCB exposure also reduced body weight, serum IGF-1, and hepatic expression of mRNAs encoding the male-specific GH-pattern-regulated CYP2C11 and CYP3A2 relative to controls (P < 0.05). PCB exposure reduced long bone length, diameter, and surface area, but increased trabecular thickness and volume (P < 0.05). Serum osteocalcin (P < 0.05), a marker and a regulator of bone formation, was reduced, but PCB exposure had no effect on the bone resorption marker RatLaps. Exposure of human intestinal Caco-2 cells to 10-100nM PCB 126 in the presence of vitamin D3 resulted in inhibition of mRNAs for the calcium transporters TRPV6 and PMCA1b (P < 0.05). In addition, PCB 126 suppressed osteoblastogenesis in primary bone marrow mesenchymal stem cell cultures which was blunted by the AhR antagonist CH-223191. These data provide novel evidence that skeletal toxicity after exposure to PCB 126 is a result of disruption of calcium homeostasis and the GH-IGF-1 axis, and involves direct AhR-mediated effects on bone formation.

Degradation of selected polychlorinated biphenyls by montmorillonite clay-templated Fe0/Ni0 bimetallic system

In this study, a montmorillonite-templated Fe0/Ni0 bimetallic material was synthesized and utilized to degrade polychlorinated biphenyls (PCBs). Two PCB congeners 3,3′,5- and 2,2′,6-trichlorobiphenyl (PCB 36 and PCB 19) were strategically selected to study the effects of PCB structure on adsorption and dechlorination processes occurring on mineral surfaces. Our results showed that montmorillonite-templated Fe0/Ni0 system could effectively reduce co-planar PCB congener (PCB 36) to biphenyl within 4h, however, for non-coplanar PCB 19, only negligible degradation was observed. The exchangeable cations in clay interlayer could also affect the reductive reactions of PCBs. For montmorillonite exchanged with less hydrated cation e.g. K+, both adsorption and dechlorination rate of PCBs were significantly greater than those with highly hydrated cation e.g. Na+. Adsorption of PCBs on montmorillonite surfaces is the key step for the dechlorination reactions. The degradation process is initiated by the intercalation of PCBs into clay interlayers, and subsequently reduced by Fe0/Ni0 bimetal via a hydrodechlorination reaction. Considering PCBs, especially some co-planar PCB congeners with dioxin-like properties, have posed significant threat to human health, this study would provide new strategies to be able to efficiently and selectively degrade the more toxic PCB congeners.

Using the kingfisher (Alcedo atthis) as a bioindicator of PCBs and PBDEs in the dinghushan biosphere reserve, China

The Dinghushan Biosphere Reserve is a nature reserve and a site for the study of tropical and subtropical forest ecosystems. Rapid industrialization and intensive electronic waste-recycling activities around the biosphere reserve have resulted in elevated levels of industrial organic contaminants in the local environment that may cause adverse effects on wildlife that inhabits this area. In the present study, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and 2 alternative brominated flame retardants (BFRs)-decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE)-were investigated in the biosphere reserve and a reference site by using the kingfisher (Alcedo atthis) as a bioindicator. Residue concentrations in kingfishers from the Dinghushan Biosphere Reserve ranged from 490 ng/g to 3000 ng/g, 51 ng/g to 420 ng/g, 0.44 ng/g to 90 ng/g, and 0.04 ng/g to 0.87 ng/g lipid weight for ∑PCBs, ∑PBDEs, DBDPE, and BTBPE, respectively. With the exception of the BTBPE, these levels were 2 to 5 times higher than those detected in kingfishers from the reference site. The contaminant patterns from the biosphere reserve were also different, with larger PCB contributions in comparison with the reference site. The estimated predator-prey biomagnification factors (BMFs) showed that most of the PCB and PBDE congeners and BTBPE were biomagnified in kingfishers from the biosphere reserve. The calculated toxic equivalent quantity (TEQ) concentrations of major coplanar PCB congeners in kingfishers from the biosphere reserve ranged from 18 pg/g to 66 pg/g wet weight, with some of these TEQ concentrations reaching or exceeding the levels known to impair bird reproduction and survival.

Detection of PCB77 by Indirect Competitive Enzyme-linked Immunosorbent Assay in Sea Sediment Samples

3,3',4,4'-Tetrachlorobiphenyl (IUPAC PCB77) is one of seven indicative polychlorinated biphenyls (PCBs) in the surface sediments. The current study presents a novel polyclonal antibody for the determination of the PCB77 using indirect competitive enzyme-linked immunosorbent assay. Under optimum conditions, PCB77 was determined within the concentration range of 0.01-100 <TEX>${\mu}g\;L^{-1}$</TEX>, with a detection limit of 0.057 <TEX>${\mu}g\;L^{-1}$</TEX>. The assays were tested for their cross-reactivity profiles using 3 selected congeners and 4 Aroclor products. The assays were highly specific for coplanar PCB congeners, but less specific for Aroclor1248. The spiked recoveries from five sediment samples were 86%-114% for PCB77 from ELISA, which were satisfactory. The current study demonstrated that the developed antiserum and immunoassay procedure can be used to detect PCB77 in environmental samples. The results of the sediment analysis were confirmed by conventional GC/ECD.

Enzyme-Linked Immunosorbent Assay with Monoclonal and Single-Chain Variable Fragment Antibodies Selective to Coplanar Polychlorinated Biphenyls

Coplanar polychlorinated biphenyls (Co-PCBs) consisting of non-ortho and mono-ortho-chlorinated PCBs are dioxin-like compounds and cause wide contamination in the environment. To monitor Co-PCB residues, it was attempted to establish an enzyme-linked immunosorbent assay (ELISA) with monoclonal and recombinant antibodies selective to Co-PCBs. When 3,3',5,5'-tetrachlorobiphenoxybutyric acid (PCBH)-keyhole limpet hemocyanin conjugate was immunized into mice, two monoclonal antibodies, Mab-0217 and Mab-4444, were obtained. 3,3',5,5'-Tetrachlorobiphenyl (PCB80) was determined with an IC(50) value of 2.6 and 0.46 ng mL(-1) in ELISA based on Mab-0217 and Mab-4444, respectively. Mab-4444 cross-reacted with Co-PCB congeners, except for PCB77 and PCB81. Mab-0217 reacted with PCB80 and cross-reacted with PCB111. A single-chain variable fragment (scFv) antibody derived from Mab-4444 was produced in recombinant Escherichia coli cells. The scFv antibody showed nearly the same sensitivity toward PCBH as the parent monoclonal antibody in ELISA. These results clearly suggested that Mab-4444 and its scFv antibodies were suitable for monitoring the representative congeners of Co-PCBs.

Morphological alterations of Vero cell exposed to coplanar PCB 126 and noncoplanar PCB 153

Polychlorinated biphenyls (PCBs) are widespread, persistent environmental contaminants that display a complex spectrum of toxicological properties. Exposure to PCBs has been associated with morphological anomalies in cell cultures. However, most mechanistic studies of PCBs' toxic activity have been focused on coplanar congeners. It is of importance to determine whether PCB treatment would influence cell configuration and whether these changes would depend on the structural characteristics of PCBs. In this study, we investigated cell morphological alteration in Vero cell cultures after exposure to coplanar PCB 126 and noncoplanar PCB 153. The survival of Vero cells was measured through the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test. Cytotoxicity results suggested that PCB congeners had a toxic, antiproliferative effect on Vero cells. Morphological studies described structural modifications and provided evidence that apoptosis might be the main cell death pathway in PCB 153-treated cells. The comparison between PCB 126 and PCB 153 indicated that the cell death mechanisms involved in coplanar or noncoplanar PCB congener exposure were different in Vero cells.

Distribution of organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) in marine sediments directly exposed to wastewater from Cortiou, Marseille

The future 'Calanque National Park' coastlines of the Bouches-du-Rhône and Var departments in France, constitute one of the ten biodiversity hot spots identified in the Mediterranean basin that receives industrial and urban wastewaters discharged from Marseille and its suburbs. Organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs) were measured in sediments collected from 12 sampling sites (C1-C12) of sewage discharge to the sea from the wastewater treatment plant of Cortiou-Marseille. This study aims to determine the extent of these compounds in the sediments and to establish the possible sources of these contaminants. Total pesticides in the sediments ranged from 1.2 to 190.6 ng g(-1) dry weight of sediment. The highest value was found at station C1, with a decreasing trend in total OC concentrations seaward. Among these compounds, the concentrations of the sum of dichlorodiphenyltrichloroethane (ΣDDT) were the highest, ranging from 0.7 to 114.3 ng g(-1). PCB concentrations, expressed as equivalent to Arochlor 1260, varied from 9.1 to 226.9 ng g(-1). Individually, the dominant coplanar PCB congeners CB-153, CB-138 and CB-101. Generally, PCB concentrations at stations C2, C3, C5 and C7 were higher than those at stations C10, C11 and C12. Through some pollution indices, we showed the long-term contamination input of these OCs (DDT, endosulfan, HCH and heptachlor cases) rather than a recent release resulting from degradation and long-term weathering (dieldrin, aldrin and methoxychlor cases). Occurrence of PCBs might be due to their resistance to degradation processes or/and chronic inputs. By comparison with available sediment quality guideline (SQG) values, the environmental significance and toxicological implications of PCBs and OCs (i) reveal the probable adverse effects for the sediments from C1, C5, C6, C9 and (ii) confirm the adverse effect for marine biota and more particularly for benthic communities at C2-C4, C7 and C8.

Comparison of structure-dependent hormetic cytotoxicity induced by coplanar and non-coplanar PCB congeners

The effect of polychlorinated biphenyls (PCBs) on Vero cell proliferation was investigated, with the attempts to assess the possible hormetic dose–response and to compare their structure-dependent toxicity. Both PCB congeners revealed low doses stimulation in our experiment. However, significant cytotoxicity was only observed in PCB 52 concentrations larger than 0.1 μg ml −1, while there was no significant inhibition in PCB 77-treated cells at concentrations selected. Furthermore, the time-dependent cytotoxic trends were different. The comparison between PCB 52 and PCB 77 indicated that the cytotoxic mechanisms involved in coplanar or non-coplanar PCB congener exposure were different, and this difference might be associated with individual genotoxicity and the release of contact inhibition, respectively.

Catalytic Role of Palladium and Relative Reactivity of Substituted Chlorines during Adsorption and Treatment of PCBs on Reactive Activated Carbon

The adsorption-mediated dechlorination of polychlorinated biphenyls (PCBs) is a unique feature of reactive activated carbon (RAC). Here, we address the RAC system, containing a tunable amount of Fe as a primary electron donor coupled with Pd as an electrochemical catalyst to potentially respond to the characteristic of contaminated sites, effectively traps and treats various PCB congeners. A dramatic increase in RAC reactivity with Pd doping at as low as 0.01% suggests its critical role for accelerating hydrodechlorination of PCBs. Characteristic adsorption and dechlorination behavior and ensuing decomposition pathways of 13 selected PCB congeners are discussed with their surface interactions with RAC. Important findings include (i) inherent dechlorination susceptibility of chlorines in para > meta > ortho position, regardless of independent or competitive conditions as well as substrate effects, (ii) favorable reduction of more toxic coplanar PCB congeners, (iii) preferential electrophilic attack to chlorines in a less substituted phenyl ring and an isolated chlorine, regardless of the steric or inductive effect as a dominant limiting factor for the dechlorination of ortho or meta PCBs, respectively, (iv) prominent dechlorination inhibition for higher ortho congeners but negligible inhibition for higher meta congeners, and (v) eventual complete dechlorination of higher PCB congeners to biphenyl.

Oxidative stress and apoptosis of Carassius auratus lymphocytes induced by nonplanar (PCB153) and coplanar (PCB169) polychlorinated biphenyl congeners in vitro

Among all the 209 kinds of polychlorinated biphenyls (PCBs) congeners, nonplanar and coplanar PCB congeners have different levels of toxicity on mammal cells such as neuronal cells, but little is known about their toxicity on fish cells although PCB congeners usually have high bioaccumulation abilities in the detected fish bodies. This study showed that 2,2',4,4',5,5'-hexacholorbiphenyl (PCB153, nonplanar congener) and 3,3',4,4',5,5'-hexacholorbiphenyl (PCB 169, coplanar congener) caused apoptosis on the isolated crucian carp (Carassius auratus) lymphocytes and the induced cytotoxicity was structure-dependent. According to the laser confocal microscope observations, apoptosis was clearly distinguished by condensation of nucleus, shrinkage and formation of apoptotic bodies. DNA fragmentation was detected by agarose gel electrophoresis. These typical morphological and biochemical characteristics indicate the occurrence of apoptosis on fish lymphocytes. According to the flow cytometry analysis, after the cells were exposed to 10 micromol/L PCBs for 3 h, the apoptotic percentage induced by PCB153 was 23.41%, while that induced by PCB169 was even higher (31.03%). Furthermore, incubating PCBs with fish lymphocytes enhanced levels of reactive oxygen species (ROS) and malondialdehyde (MDA), clearly indicating the presence of oxidative stress and lipid peroxidation. Our data also demonstrate that the different cytotoxic effects induced by coplanar and nonplanar PCBs were correlated with their structural characteristics and the coplanar congener was more cytotoxic than nonplanar congener. This study suggests that cytotoxicity mechanisms of the PCB congeners on fish lymphocytes depend on their planarity and chemical structures.

Polychlorinated dibenzo‐p‐dioxin, polychlorinated dibenzofuran, and polychlorinated biphenyl accumulation in white‐tailed deer (Odocoileus virginianus) near a magnesium smelter in Quebec, Canada

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) as well as polychlorinated biphenyls (PCBs) were measured in white-tailed deer (Odocoileus virginianus) near a magnesium-refining facility in Quebec (Canada) known to be a source of chlorinated organic compounds to the area. We compared contaminant concentrations in deer caught one year before the start of magnesium production with those measured three years later. Total PCB concentrations were spatially uniform in deer before magnesium production, but after magnesium production began, concentrations were higher near the smelter and decreased with distance. Many of the midrange PCB homologues that bioconcentrate most in deer showed similar relationships. Concentrations of coplanar PCB congeners and cytochrome P4501A expression in deer liver were examined in a subset of the samples, and these also showed a significant inverse relationship with distance after magnesium production began. This pattern was not observed for PCDD/F concentrations in deer. The risk involved for the human population in consuming local deer meat was assessed by applying contaminant concentrations measured in the present study to Health Canada consumption guidelines. Contaminants in deer were not shown to pose a serious risk to the population, but the number of portions of deer from beyond 20 km that could be safely consumed was less restrictive than the number for deer from within a 5-km radius of the magnesium smelter.

Potential Hazards of Environmental Contaminants to Avifauna Residing in the Chesapeake Bay Estuary

A search of the Contaminant Exposure and Effects-Terrestrial Vertebrates (CEE-TV) database revealed that 70% of the 839 Chesapeake Bay records deal with avian species. Studies conducted on waterbirds in the past 15 years indicate that organochlorine contaminants have declined in eggs and tissues, although p,p’-DDE, total polychlorinated biphenyls (PCBs) and coplanar PCB congeners may still exert sublethal and reproductive effects in some locations. There have been numerous reports of avian die-off events related to organophosphorus and carbamate pesticides. More contemporary contaminants (e.g., alkylphenols, ethoxylates, perfluorinated compounds, polybrominated diphenyl ethers) are detectable in bird eggs in the most industrialized portions of the Bay, but interpretation of these data is difficult because adverse effect levels are incompletely known for birds. Two moderate-sized oil spills resulted in the death of several hundred birds, and about 500 smaller spill events occur annually in the watershed. With the exception of lead, concentrations of cadmium, mercury, and selenium in eggs and tissues appear to be below toxic thresholds for waterbirds. Fishing tackle and discarded plastics, that can entangle and kill young and adults, are prevalent in nests in some Bay tributaries. It is apparent that exposure and potential effects of several classes of contaminants (e.g., dioxins, dibenzofurans, rodenticides, pharmaceuticals, personal care products, lead shot, and some metals) have not been systematically examined in the past 15 years, highlighting the need for toxicological evaluation of birds found dead, and perhaps an avian ecotoxicological monitoring program. Although oil spills, spent lead shot, some pesticides, and industrial pollutants occasionally harm Chesapeake avifauna, contaminants no longer evoke the population level effects that were observed in Ospreys (Pandion haliaetus) and Bald Eagles (Haliaeetus leucocephalus) through the 1970s.

Residue levels of DDTs and toxic evaluation of polychlorinated biphenyls (PCBs) in Scyliorhinus canicula liver from the Mediterranean Sea (Italy)

Organochlorine compounds, such as polychlorinated biphenyls (PCBs) and DDT compounds (DDTs), are important components of the chemical pollutants found in all parts of the marine environment. They are potentially hazardous to living systems because of their inclination to bioaccumulate in the lipid component of biological species and their resistance to degradation. Prolonged exposure to these pollutants can interfere with normal physiology and biochemistry of the marine organisms. It is, in fact, well-known that these compounds exhibit a broad range of toxicological responses, including immunotoxicity, reproductive deficits, teratogenicity, endocrine toxicity and carcinogenity/tumor promotion (Ahlborg et al., 1994). The occurrence and severity of the toxic effects depend on various factors, such as the level of pollutants in the organism, the susceptibility of the species and the duration of exposure. In the last decade, particular emphasis has been placed upon the toxicity of some PCB congeners, the so-called ‘‘coplanar’’ or ‘‘dioxin-like’’ PCBs, which may adapt a planar conformation and activate the aryl hydrocarbon (Ah) receptor. These compounds are thought to share a common mode of toxic action with dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin,TCDD), the most toxic member of the planar chlorinated hydrocarbons. There is an extensive amount of literature reporting the levels of these contaminants in marine organisms occupying higher trophic levels, such as dolphins (Watanabe et al., 2000; Storelli and Marcotrigiano, 2000a), whales (Gauthier et al., 1998; Ross et al., 2000), and seals (Tarasova et al., 1997), whereas comparatively little data are available for elasmobranch fish (Serrano et al., 1997, 2000), especially from the Mediterranean Sea (Storelli and Marcotrigiano, 2001; Storelli et al., 2003a, 2004). With respect to these literature findings, this study investigated the accumulation profile of individual PCB congeners and the levels of DDTs and its metabolites in the liver of a small cartilaginous fish, Scyliorhinus canicula, from the Mediterranean Sea. In addition, 2,3,7,8-TCDD equivalency of the monoand non-ortho coplanar PCB congeners Edited by Bruce J. Richardson

Uncoupling of cytochrome P450 1A and stimulation of reactive oxygen species production by co-planar polychlorinated biphenyl congeners

The non- ortho-polychlorinated biphenyl (PCB) congener 3,3′4,4′-tetrachlorobiphenyl (PCB 77) can uncouple the catalytic cycle of fish (scup) cytochrome P4501A (CYP1A) and mammalian (rat, human) CYP1A1, stimulating release of reactive oxygen species (ROS). PCB 77 also inactivates CYP1A in an NADPH-, oxygen-, and time-dependent process, linked to uncoupling. We addressed a hypothesis that planar halogenated hydrocarbons generally will uncouple CYP1A. Thus, additional PCB congeners including non- ortho-3,3′,4,4′,5′-pentachlorobiphenyl (PCB 126) and 3,3′,4,4′,5,5′-hexachlorobiphenyl (PCB 169), mono- ortho-2,3,3′,4,4′-pentachlorobiphenyl (PCB 105) and di- ortho-2,2′,5,5′-tetrachlorobiphenyl (PCB 52), as well as the polycyclic aromatic hydrocarbon benzo[a]pyrene (B[a]P), were examined for their ability to stimulate microsomal ROS production and to inactivate CYP1A. Incubated without NADPH, non- ortho-PCB 126 and -PCB 169 both inhibited microsomal CYP1A activity (ethoxyresorufin O-deethylase; EROD). When NADPH was included, these congeners caused a progressive inactivation of CYP1A, in addition to the inhibition. The determined K Inact values for inactivation were 0.14 and 0.08 μM, respectively, for PCB 126 and PCB 169, similar to the 0.05 μM for PCB 77 previously reported. The mono- ortho-PCB 105 weakly inhibited and weakly inactivated CYP1A. The di- ortho-PCB 52 neither inhibited nor inactivated CYP1A. Alone, B[a]P strongly inhibited CYP1A, but when NADPH was added that inhibition was reversed, apparently by metabolic depletion of the substrate, and there was no inactivation. PCB 126 and PCB 169 stimulated release of ROS from induced liver microsomes, while B[a]P, PCB 52 and PCB 105 did not. ROS release and CYP1A inactivation stimulated by the non- ortho-PCB 126 and PCB 169 indicate an uncoupling of CYP1A like that previously shown with PCB 77. The uncoupling and release of ROS further suggest a participation of CYP1A in the oxidative stress associated with some planar halogenated aryl hydrocarbon receptor agonists.

The Relationship Between Noncoplanar PCB-Induced Immunotoxicity and Hepatic CYP1A Induction in a Fish Model

Abundant literature exists demonstrating the immunomodulating effects of polychlorinated biphenyls (PCBs). To date, most of the research has focused on dioxin-like coplanar PCB congeners because of their high affinity for the aryl hydrocarbon receptor (AhR) and cytochrome P450-inducing capability. For this study, the impact of two structurally different PCB congeners on the immune responsiveness of bluegill sunfish (Lepomis macrochirus) was examined to evaluate the immunotoxic potential of each congener (as separate entities) and to relate effects on immune function with hepatic CYP1A induction. Fish received a single intraperitoneal injection of the: coplanar congener, PCB 126 (0.01 or 1.0 μg/g BW); noncoplanar PCB 153 (5.0 or 50.0 μg/g BW); or, the corn oil vehicle. PCB-induced effects on innate and cell-mediated immune parameters, and on hepatic CYP1A protein induction were evaluated in fish sacrificed 1, 3, 7, 14 or 21 days post-injection. In the absence of CYP1A induction, PCB 153 increased kidney phagocyte-mediated superoxide production 3 d post-injection, and at the highest dose suppressed B- and T-lymphocyte proliferation after 3 and 7 days, respectively. Treatment of fish with PCB 126 had no effect on oxyradical production, but altered B-lymphocyte proliferation after 1 day, also in the absence of CYP1A induction. Hepatic CYP1A was only induced in fish exposed to the highest PCB 126 dose; protein induction appeared at 3 d post-injection and persisted for up to 21 days. Taken together, these results demonstrate that exposure to different PCB congeners can alter immune function in the absence of CYP1A induction, suggesting that mechanisms other than the AhR pathway may play a role in PCB-induced immunotoxicity, particularly for the noncoplanar congeners.

Reference values of coplanar and non-coplanar PCBs in serum samples from two Italian population groups

The main goal of this study is to establish the reference values of individual Polychlorinated biphenyl (PCB) congeners in non-occupationally exposed subjects. Since the PCB pattern in human serum is related to the living area, two different population groups from North and Central Italy, were compared. Serum concentrations of both coplanar and non-coplanar PCB congeners were measured by using gas chromatography coupled with low-resolution mass spectrometry (HRGC–LRMS). A fast and reliable method for the determination of 60 congeners had been previously validated. Its reliability was further verified by using high-resolution mass spectrometry. Thirty-one congeners out of 60 were found at detectable concentrations in at least one sample. The mean value for total PCBs was found to be 2.48 and 3.93 μg/L for the two population groups. Eight dioxin-like PCBs were detected. In accordance with the findings from the literature, the most abundant congeners were found to be 153, 138, 180, and 170. Both univariate and multivariate analysis showed that age is a significant determinant of PCB concentrations. The correlation increased with increasing chlorination. Slight differences in the PCB pattern were observed in the two population groups.

Coplanar Polychlorinated Biphenyls Activate the Aryl Hydrocarbon Receptor in Developing Tissues of Two TCDD-Responsive lacZ Mouse Lines

In utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can have an immediate impact on developmental processes that then lead to long-term deficits in function. To define the specific tissues affected by TCDD during development, we developed a lacZ-reporter gene mouse model driven by activation of the aryl hydrocarbon receptor (AhR). Exposure to TCDD on gestational day (GD) 14 results in strong activation of the lacZ transgene in numerous tissues including fore and hind paws, ear, and genital tubercle. Experiments were conducted to examine the ability of alternative AhR ligands to activate our model system. The coplanar polychlorinated biphenyl congeners 3,4,5,3',4'-pentachlorobiphenyl (PCB126) and 3,4,3',4'-tetrachlorobiphenyl (PCB77) both induced staining in fetal tissues identical to that observed following TCDD exposure. Exposure of fetuses to the PCB mixture Aroclor 1254 and the non-coplanar congener 2,3,6,2',5'-pentachlorobiphenyl (PCB95) did not result in any activation of the lacZ transgene. In addition to the testing of alternative ligands, another line of reporter mice was generated to determine the potential influence of the site of insertion of the lacZ transgene on the reported observations. Both TCDD and the coplanar PCBs induced a similar pattern of staining in the new line as compared to that observed in the original lacZ reporter mouse line. The ability of AhR ligands, other than TCDD, to activate the AhR-mediated transgene, in combination with the insertion-site independence of the response, strengthens the data previously derived from this model and increases the utility of this system for investigations examining AhR-mediated events during development.

Bioremediation Monitoring

Vol. 113, No. 7 PerspectivesOpen AccessBioremediation Monitoring Steven D. Aust Steven D. Aust Search for more papers by this author Published:1 July 2005https://doi.org/10.1289/ehp.113-a444aAboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit In their article published in the February issue of EHP, Ganey and Boyd (2005) made some excellent points about the potential pitfalls of simply assaying for the disappearance of an environmental pollutant during or as a result of bioremediation. This is important because it would be wrong to leave a metabolite that might pose as much or even more risk then the original chemical of interest.Ganey and Boyd (2005) used the bio-remediation of polychlorinated biphenyls (PCBs) as an example, which was an excellent choice. However, the subject of metabolism of the PCB bioremediation metabolites should also be considered. As chlorines are removed by bioremediation, the less-chlorinated products could be more readily metabolized by many species exposed to the bioremediated material. That is, less-heavily chlorinated products (or intermediates) of bioremediation may be less toxic because of shorter half-lives due to metabolism. This phenomenon can be exemplified by work we conducted years ago at Michigan State University. We showed that 3,4,3′,4′-tetrabromobiphenyl was less toxic than 3,4,5,3′,4′,5′-hexabromobiphenyl, even though it was bound at higher affinity by the dioxin receptors because it was more readily metabolized and eliminated (Millis et al. 1985).Commercial preparations contain few or no strictly coplanar PCB or polybrominated biphenyl congeners. This fact does not seem to be appreciated, and the impression is sometimes given that those very toxic congeners are in the environment. In fact, the coplanar polyhalogenated biphenyls probably receive way too much attention, most likely because they were used rather extensively in research; however, they were used only as model toxic congeners. The synthesis of strictly coplanar halogenated biphenyls (i.e., 3,4,3′,4′-PCB) is much different from that of the commercial preparations (which was by simple halogenation of biphenyl). Phenyl is strongly ortho-para directing, leading to non-coplanar halogenated biphenyls. The initial para and/or ortho halogenation makes for an even stronger ortho-para directive. Thus, the major components will be non-coplanar halobiphenyls. Only very small amounts of single ortho halobiphenyls can be found in commercial mixtures, and these mixtures are quite ineffective in eliciting effects associated with binding by the dioxin receptor.ReferencesGaney PE, Boyd SA. 2005. An approach to evaluation of the effect of bioremediation on biological activity of environmental contaminants: dechlorination of polychlorinated biphenyls. Environ Health Perspect 113:180-18515687055. Link, Google ScholarMillis CD, Mills RA, Sleight SD, Aust SD. 1985. Toxicity of 3,4,5,3′,4′,5′-hexabrominated biphenyl and 3,4,3′,4′-tetrabrominated biphenyl. Toxicol Appl Pharmacol 78:88-952994254. Crossref, Medline, Google ScholarFiguresReferencesRelatedDetails Vol. 113, No. 7 July 2005Metrics About Article Metrics Publication History Originally published1 July 2005Published in print1 July 2005 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

Bioaccumulation of Organochlorines in Crows from an Indian Open Waste Dumping Site: Evidence for Direct Transfer of Dioxin-Like Congeners from the Contaminated Soil

To assess the significance of waste dumping sites as a source of chemical contamination to ecosystems, we analyzed the residue levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and other organochlorines in the breast muscle of crows from a dumping site in the south of Chennai city, South India. Crows from the dumping site contained significantly higher total TEQs (60 +/- 27 pg/g lipid wt) than those from the reference sites (26 +/- 18 pg/g lipid wt). Especially, certain dioxin-like coplanar PCB congeners (Co-PCBs), such as CB-77 and CB-105, whose source is commercial PCBs,were significantly higher in crows from the dumping site than those from the reference sites. Profiles of PCDDs/DFs and Co-PCBs in crows from the dumping site were similar to those of soil at the same site, which was confirmed by principal component analysis. Furthermore, significant positive correlations were obtained between the congener-specific bioconcentration factors (BCFs) of PCDDs/DFs estimated from concentrations in crows and soil from the dumping site and the theoretical BCFs calculated from water-particle and lipid-water partitioning coefficients. On the other hand, the estimated BCFs had significant negative correlations with the molecular weight of PCDDs/DFs, indicating that molecular size limits their bioaccumulation. These results suggest that dioxin-like congeners in the soil of the dumping site were transferred directly to the crows through the ingestion of on-site garbage contaminated with soil, rather than through trophic transfer in the ecosystem. The present study provides insight into the ecological impacts of dumping sites.