Toxic 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.

Polychlorinated biphenyls in bovine milk from a typical informal electronic waste recycling and related source regions in southern India before and after the COVID-19 pandemic outbreak

For more than a decade, Chennai city in southern India has been evidenced with informal electronic waste (e-waste) recycling and open burning practices as the potential sources for polychlorinated biphenyls (PCBs). PCBs can bioaccumulate in livestock particularly cows grazing on the contaminated soil. The outbreak of the COVID-19 pandemic led to additional challenges associated with waste management practices. Hence this study aims to elucidate twenty-five PCB congeners in bovine milk from the previously reported PCB source regions in Chennai and the suburbs before and after about three years of the pandemic outbreak along electronic waste recycling (EWR), open burning dumps (OBD), and residential (RES) transects. The geomean concentration of Ʃ25PCBs in ng/g lipid weight (lw) followed a decreasing trend of EWR (13 ng/g lw) > OBD (8 ng/g lw) > RES (4 ng/g lw). Over 80 % of PCBs stemmed from EWR and OBD transects before and after the pandemic. However, a significant surge in the level of PCB-52 was observed in the OBD transect after the pandemic outbreak. Most toxic PCB congeners, PCB-126 and -169 were significant contributors to TEQs in EWR and OBD transects and can be reasoned with the burning of waste materials and mixed plastics in these transects. The highest average daily dose (ADD) exposure risk was for children from EWR and was significantly higher (p < 0.05) than other transects. Mean ADD-induced TEQ (6.6 pg TEQ/kg-bw/day) from the cows grazing around Kodungaiyur dumpsite slightly exceeded the EU guideline of 5.5 pg TEQ/kg-bw/day after the outbreak of the pandemic due to PCB-126. However, none of the samples exceeded the US FDA (1.5μg/g milk fat) recommendation limits for PCBs in milk fat. Prolonged exposure to such persistent organic pollutants interlinked with the burning of mixed waste in the open dumps can be a public health concern.

2,3′,4,4′,5-Pentachlorobiphenyl induces mitochondria-dependent apoptosis mediated by AhR/Cyp1a1 in mouse germ cells

Polychlorinated biphenyls (PCBs) are environmental organic pollutants widely used in industry that can bioaccumulate and affect the reproductive systems of male animals of different species. 2,3′,4,4′,5-Pentachlorobiphenyl (PCB118) is a representative of the 209 toxic PCB congeners. In this study, male mice were exposed to PCB118 at 0, 50, and 500 μg/kg/day for 35 days beginning 3–4 weeks after birth. The results of the study showed that PCB118 exposure during puberty reduced testicular quality, caused tissue damage, decreased sperm motility and sperm count, and increased malformation and testicular cell apoptosis in mice. Moreover, PCB118 increased the oxidative stress levels in sperm and testicular tissue and the expression of aryl hydrocarbon receptor (AhR) and Cyp1a1 and siginificantly decreased the level of nuclear factor-erythroid 2-related factor 2 (Nrf2). The results indicate that PCB118 can activate the AhR/Cyp1a1 pathway and inhibit Nrf2 expression to aggravate testicular oxidative stress and induce cell apoptosis, resulting in testicular and sperm quality damage.

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.

Organochlorine contaminants in tissues of common bottlenose dolphins Tursiops truncatus from the northeastern part of the Adriatic Sea

Levels of 24 organochlorine compounds, including toxic mono-ortho PCB congeners, were determined in the organs and tissues (blubber, kidney, lung, muscle, liver, heart) of 13 common bottlenose dolphins (Tursiops truncatus) stranded between 2000 and 2005 in the northern part of the Croatian territorial waters of the Adriatic Sea. Polychlorinated biphenyls (PCBs) were found at higher concentrations in comparison with organochlorine pesticides (OCPs) in all of the analyzed tissues. Sums of six indicator congeners (Σ6PCB) constituted around 50% of the total PCB amount, while PCB-153 and PCB-138 were found to have the highest concentrations. Among the seven investigated OCPs, p,p′-DDE was found at the highest concentrations.In blubber, mean values of 22,048 and 11,310ngg−1 wet weight were determined for ΣPCB and ΣDDT, respectively. Much lower concentrations were found in muscle samples, followed by similar concentrations in kidneys, liver and heart, while the lowest levels of organochlorine contaminants were found in lungs.The results indicate that p,p′-DDT is still being introduced in the Mediterranean region. PCB concentrations are among the highest found in this region and toxicological assessments indicate that the health of this specie is at high risk.

Levels of PCBs in wild bird eggs: Considering toxicity through enzyme induction potential and molecular structure

Polychlorinated biphenyls (PCBs) were analysed in wild bird eggs from industrialised areas in South Africa. The concentration, congener profile, feeding guild, potential associated risk and biology were investigated. PCBs were detected in all eggs with 30 congeners present in more than 80% of the samples. Σ34PCB concentrations ranged between 0.9 and 296ngg−1wet weight (ww). The metabolic potential of the PCB metabolic groups showed good agreement with the biodegradability of the individual congeners. Phenobarbital-type (PB-type) inducer PCBs were prevalent, indicating the predominance of less toxic PCB congeners. However, non-ortho PCBs which were not included in the current analyses, could affect the toxic potential of the PCBs in the eggs requiring more investigation. Although the current levels of PCBs measured do not indicate a health risk to the birds assessed, the presence of mono-ortho PCBs at appreciable levels motivates for the assessment of dioxin-like chemicals in wild bird eggs.

Levels and Distribution of PCBs and Organochlorine Pesticides in the Air, Pine Needles, and Human Milk

This review presents the findings on the distribution and levels of 20 congeners of polychlorinated biphenyls (PCBs) and 7 organochlorine pesticides (OCPs) all over the world, based on measurements in samples of air, human milk and pine needles. The Institute for Medical Research and Occupational Health has been conducting research in all three matrices for many years, and this review summarises its results too. Significant decrease in concentrations of organochlorine compounds has been seen after the legal ban of their use, but that decresing trend has been slowed down and they are still found in all samples. In general, higher PCB levels are found in samples from urban locations, pesticides levels are higher in samples from locations where has been their probable usage in agriculture, while HCB levels are usually indicator of industrial activity.γ-HCH has been found in the highest concentration in air and pine needles samples, while in humans DDE and β-HCH are the most abundant compounds. Indicator PCB congeners are also differently present in environment and humans: in air and pine needles lower-chlorinated, more volatile PCB congeners have higher concentrations while in humans that goes for more persistent higher-chlorinated PCB congeners. Among toxic ortho-substituted PCB congeners in human and environmental samples the most abundant is PCB-118 while three non-ortho substituted congeners (PCB-77, PCB-126 and PCB-169) that are the most toxic ones are rarely detected. From organochlorine pesticides, DDD is found in lowest concentrations in all samples.

CONGENER PATTERN AND TOXICITY OF POLYCHLORINATED BIPHENYLS IN AQUATIC ORGANISMS FROM AN ELECTRONIC AND ELECTRICAL WASTE AREA

Electronic and electrical waste (E-waste) is a waste type consisting of any broken or unwanted electrical or electronic appliance. Obsolete E-waste has become a serious problem. Many previous studies showed that persistent organic pollutants (POPs) and heavy metals caused serious contamination in air, soil, sediment and freshwater. It is drawing more and more attentions because of its adverse impacts on environment and human health. According to the State Environmental Protection Administration of China, 70% of worldwide e-waste has been sent to China. Taizhou region in Zhejiang Province is one of the most intensive E-waste processing sites in China. Polychlorinated biphenyls (PCBs) were widely used worldwide as coolants and insulators in electrical capacitors and transformers, and as plasticizers in paint and rubber sealant. Large quantities of PCBs have since entered the environment through leakage, disposal, and evaporation. PCBs stability is also responsible for their continued presence in the environment even decades. Environmental levels of PCBs are traditionally measured as total PCB based on Aroclor equivalent analysis, as opposed to congener-specific concentrations, due to analytical limitations and/or cost differentials. To evaluate the true risk of PCBs to human and ecosystem health, more complex and, in turn, costly Dioxin-Like PCB-specific analytical methods (e. g., U. S. EPA method 1668a) are available. Dioxin-like PCBs (dl-PCBs) are a group of 12 PCBs that share a common toxic mechanism with the most toxic dioxin compound (i.e., 2 3, 7, 8-tetrachlorodibenzop-dioxin or 2, 3, 7, 8-TCDD) and generally are among the most toxic PCB congeners as they incur toxic effects at relatively lower concentrations than those of non-dl-PCBs. In the present study, samples of winkle, loach and crucian carp were collected from the e-waste area (Taizhou, Zhejing) in 2006. DI-PCBs were determined in the samples using isotope dilution Gas Chromatography/Mass Spectrometry (CC/MS) method. Our results showed that the average concentrations of PCBs were 1303. 53, 3845. 00 and 5645. 34 ng/g lipid weight in winkle, loach and crucian carp, respectively. Toxic equivalencies (TEQs) were determined to be 1.35, 8.44 and 29.18 pg WHO-TEQ/g wet weight in winkle, leach and crucian carp, respectively. TEQs in winkle and crucian carp exceed the European maximum permissible level (2006) of TEQs in fish for human food. In addition, PCB 118 was major congener and constituted 57.73%-61.22% and 44.27%-50.61% of total PCBs and TEQs, respectively. Furthermore, PCB 118 was found to have linear correlations to the total PCBs and TEQs. The correlative coefficients (R-2) were 0.9988 (P < 0.0001) and 0.9873 (P < 0.0001). These results indicated that aquatic organisms from the e-waste area have been seriously contaminated by PCBs which might come from Aroclor 1254 released from E-waste dismantling.

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.

Effects of contaminant exposure on reproductive success of ospreys (Pandion haliaetus) nesting in delaware river and bay, USA

Despite serious water-quality problems and pollutant loading and retention, Delaware River and Bay (USA) provide important wildlife habitat. In 2002, we conducted a comprehensive evaluation of contaminant exposure and reproduction of ospreys (Pandion haliaetus) breeding in Delaware River and Bay. Sample eggs were collected from 39 nests and analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), and mercury; a subset of 15 eggs was analyzed for perfluorinated compounds and polybrominated diphenyl ethers (PBDEs). The fate of each nest was monitored weekly. Concentrations of 10 organochlorine pesticides or metabolites, total PCBs, and several toxic PCB congeners were greater (p < 0.05) in eggs collected between the Chesapeake and Delaware Canal (C and D Canal) and Trenton (Delaware River and northern Bay) compared to other sites. Concentrations of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE; 0.785-3.84 microg/g wet wt) and total PCBs (5.50-14.5 microg/g wet wt) in eggs collected between the C and D Canal and Trenton were similar to levels recently found in the Chesapeake Bay. In all study segments, at least one young fledged from 66 to 75% of nests. Productivity for Delaware Inland Bays (reference area) and southern Delaware Bay was 1.17 and 1.42 fledglings/active nest, respectively; north of the C and D Canal, productivity was 1.00 fledgling/active nest, which is marginally adequate to maintain the population. Using these data, a logistic regression model found that contaminant concentrations (p,p'-DDE, heptachlor epoxide, chlordane and metabolites, and total PCBs) were predictive of hatching success. Several perfluorinated compounds and PBDEs were detected in eggs at concentrations approaching 1 microg/g wet weight. These findings provide evidence that contaminants continue to be a significant stressor on osprey productivity in the northern Delaware River and Bay.

Polychlorinated Biphenyls Cause Developmental Enamel Defects in Children

The aim of this study was to evaluate the effects of long–term exposure to polychlorinated biphenyls (PCBs) on developing dental enamel. 202 8– to 14–year–old children who were pre– and post–natally exposed to PCBs in the contaminated region of Bela Krajina, Slovenia, were studied. 202 controls from Bršljin were matched for age and sex. Risk assessment was based on the concentrations of toxic PCB congeners in the diet. Levels of PCBs in dentine were used to validate exposure. PCB levels were analysed by high–resolution gas chromatography. The prevalence of developmental defects of enamel was assessed using the FDI Index. Developmental defects of enamel in permanent teeth were found in 71.3% of exposed children, compared to 49.5% in the control group. The enamel was abnormal in 21.9% of the permanent index teeth of exposed children and in 12.7% of the control children. The difference was statistically significant (χ² = 84.18; p = 0.0019), mostly on account of demarcated opacities and hypoplasia. The extent of the defects was also greater in the exposed group (χ² = 61.3; p = 0.0001). No significant correlations were found between PCB exposure and developmental defects in deciduous teeth. In conclusion, our results showed that long–term exposure to PCBs may cause developmental defects of enamel.

Determination of dioxins/furans and PCBs by quadrupole ion‐trap gas chromatography–mass spectrometry

The versatility and sensitivity of the quadrupole ion trap tandem mass spectrometer has been applied to the determination of polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs), and of polychlorinated biphenyls (PCBs). A brief introduction to the theory of ion confinement in a quadrupole ion trap permits discussion of ion trajectory stability, mass-selective ion ejection, the frequencies of ion motion, and the role of resonant excitation of ion motion. The tandem mass spectrometric examination of PCDDs and PCDFs eluting and co-eluting from a gas chromatographic column is described. Illustrative examples are given of the analysis of field samples containing PCDDs and PCDFs. A comparison is presented of the performance of each of a quadrupole ion trap tandem mass spectrometer, a triple stage quadrupole mass spectrometer, and a sector instrument of relatively high mass resolution for the determination of PCDDs and PCDFs. This comparison is made with respect to instrument tuning, calibration plots, detection limits, ion signals at low concentration, relative response factors, ionization cross-sections, and the examination of field samples. The application of quadrupole ion trap tandem mass spectrometry to the examination of PCBs is focused upon those PCB congeners that have the greatest toxicity. 39 congeners of the total of 209 PCB congeners have been identified as having the greatest toxicities. Chemical ionization has been used for the determination of co-eluting congeners #77 and #110 where the toxicity of the former is much greater than that of the latter. An analytical protocol, based on the variation of molecular ion fragmentation according to the degree (or absence) of chlorine ortho-substitution, has been proposed for distinguishing between toxic and nontoxic PCB congeners. © 2000 John Wiley & Sons, Inc., Mass Spec Rev 19: 305–365, 2000

Determination of dioxins/furans and PCBs by quadrupole ion-trap gas chromatography-mass spectrometry.

The versatility and sensitivity of the quadrupole ion trap tandem mass spectrometer has been applied to the determination of polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs), and of polychlorinated biphenyls (PCBs). A brief introduction to the theory of ion confinement in a quadrupole ion trap permits discussion of ion trajectory stability, mass-selective ion ejection, the frequencies of ion motion, and the role of resonant excitation of ion motion. The tandem mass spectrometric examination of PCDDs and PCDFs eluting and co-eluting from a gas chromatographic column is described. Illustrative examples are given of the analysis of field samples containing PCDDs and PCDFs. A comparison is presented of the performance of each of a quadrupole ion trap tandem mass spectrometer, a triple stage quadrupole mass spectrometer, and a sector instrument of relatively high mass resolution for the determination of PCDDs and PCDFs. This comparison is made with respect to instrument tuning, calibration plots, detection limits, ion signals at low concentration, relative response factors, ionization cross-sections, and the examination of field samples. The application of quadrupole ion trap tandem mass spectrometry to the examination of PCBs is focused upon those PCB congeners that have the greatest toxicity. 39 congeners of the total of 209 PCB congeners have been identified as having the greatest toxicities. Chemical ionization has been used for the determination of co-eluting congeners #77 and #110 where the toxicity of the former is much greater than that of the latter. An analytical protocol, based on the variation of molecular ion fragmentation according to the degree (or absence) of chlorine ortho-substitution, has been proposed for distinguishing between toxic and nontoxic PCB congeners.

Gas chromatographic retention index system for polychlorinated biphenyls: possibilities and limitations

The identification of individual polychlorinated biphenyls (PCBs) congeners would be easier if a proper reference series were available to calculate retention indices when using electron capture detectors, which are insensitive to the n-alkanes. In a previous work, a mixture of PCBs showing a linear dependence of retention on the number of chlorine atoms in both isothermal and programmed temperature analysis was suggested for reference purposes. Retention index values referred to this series, I PCB, can be calculated and used for identification. In this work a wide collection of columns was tested in order to check the linearity of the proposed reference series. The effect of the initial temperature and heating rate of the programmed runs on the reproducibility of the results was investigated. Retention data of the congeners belonging to the reference series are given together with retention indices of toxic PCB congeners calculated for various columns. The inversion of the elution order or the shift of retention values on columns of different polarities are shown.

Bioaccumulation profiles of polychlorinated biphenyls including coplanar congeners and possible toxicological implications in Baikal seal ( Phoca sibirica)

Isomer specific concentrations of individual polychlorinated biphenyls (PCBs) including toxic non- ortho (IUPAC 77, 126, 169), mono- ortho (105, 118, 156) and di- ortho (137, 138, 153, 180) coplanar congeners were determined in the blubber of 40 Baikal seals ( Phoca sibirica) and as their fish diet collected from Lake Baikal, Siberia. Residue levels of total PCBs in Baikal seals were noticeably high and comparable to those reported for seals from the North Sea, suggesting the recent usage of this compound in the watershed of Lake Baikal. Non-, mono-, and di- ortho coplanar congeners were also detected in Baikal seals and fish. An approach to estimate bioaccumulation profiles of PCB congeners revealed that the non- ortho PCBs, IUPAC 77, 126 and 169 seemed to be less persistent than other congeners. Furthermore, selective biotransformation of PCB congeners having either meta-para vicinal H atoms or both adjacent chlorinated meta-para and ortho-meta positions has been suggested. Comparison of 2,3,7,8-TCDD toxic equivalents (TEQ) of non-, mono- and di- ortho coplanar congeners in Baikal seals with those for other marine mammals suggested higher enrichment of mono- ortho congeners, particularly IUPAC 105 and 118, which contributed significantly to the total TEQs in Baikal seals. Results imply that the TCDD-like toxicity is relatively serious in Baikal seals, because of the enrichment of these toxic PCB congeners in tissues.

A Monoclonal Immunoassay for the Coplanar Polychlorinated Biphenyls

Polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants with diverse toxic, teratogenic, reproductive, immunotoxic, and tumorigenic effects. Three of the least abundant of the 209 PCB isomers (congeners) are the most toxic and most difficult to quantify. These are 3,4,3',4'-tetrachlorobiphenyl, 3,4,3',4',5'-pentachlorobiphenyl, and 3,4,5,3',4',5'-hexachlorobiphenyl (IU-PAC No. 77, 126, and 169, respectively). An immunizing hapten was designed to retain the 3,4,3',4' chlorine-substitution pattern and coplanarity characteristic of these toxic congeners. The optimal competitors for immunoassay were weaker binding distinctive single-ring fragments of the PCBs. A monoclonal antibody designated S2B1 was derived and used in direct (antibody-capture) competitive enzyme immunoassays (EIAs). The EIAs are highly specific for non-ortho-substituted congeners and do not recognize the more prevalent but much less toxic noncoplanar PCB congeners or 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran, or dichlorobenzenes. Hapten and competitor design for this assay suggests a basis for development of sensitive EIAs for other classes of PCB congeners.

The ecotoxicology of coplanar polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) have been recognized for over 25 years as global environmental contaminants. However, many PCB congeners may be relatively harmless, while a small group of PCB congeners are highly toxic to biota. The toxic coplanar PCB congeners are chlorinated at meta positions and at one or none of the ortho positions on the biphenyl ring, thus resembling 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in molecular configuration. In vitro and in vivo toxicity tests with rodents, fish, and birds have shown that the coplanar PCB congener 126 is almost as toxic as TCDD. Several coplanar PCBs (e.g., 77, 126, 105, 118) are present in biota at parts per billion concentrations, which is orders of magnitude higher than concentrations of TCDD. Thus, coplanar PCBs may account for over 95% of the dioxinlike toxic activity affecting biota, such as fish-eating birds in the Great Lakes. There is some evidence that the toxicokinetics of coplanar PCBs in organisms differs from that of other PCB homologues. If coplanar PCBs are more persistent than their homologues, they could become enriched in biota as they pass up through the food chain (i.e., trophic enrichment), or as overall PCB levels decline with time (i.e., temporal enrichment). Overall, the available data do not support the concept of trophic or temporal enrichment in the environment.Key words: polychlorinated biphenyls, coplanar, toxic equivalents, kinetics, mixed function oxidase, 7-ethoxyresorufin-O-deethylase.

Analysis of polychlorinated biphenyls by quadrupole ion trap mass spectrometry. Part II: Comparison of mass spectrometric detection using electron impact and selected‐ion chemical ionization with electron capture detection

AbstractThe responses of selected‐ion monitoring of electron impact mass spectra and selected‐reagent‐ion chemical ionization mass spectra of polychlorinated biphenyls (PCBs), relative to that of congener 153, have been determined for some 60 PCBs contained in four standard mixtures. The PCB congeners examined cover a wide range of toxicities. Average responses have been determined for PCBs as a function of both the total number of chlorine substituents and the number of ortho‐substituents. Average relative responses and relative responses of individual congeners have been compared with Literature values of relative responses obtained by electron‐capture detection. Detection limits for electron ionization and C2H chemical ionization mass spectrometry, determined as the mass of congener 153 injected on column and yielding a signal‐to‐noise ratio of 5:1 were 0.76 pg and 30 pg, respectively, compared to some 70 fg for electron‐capture detection. An initial exploration and evaluation have been carried out, of the potential value of using a toxicity index to define the total toxicity of a sample; such an index is based on 39 non‐ and mono‐ortho substituted PCBs. Electron ionization, when combined with selected‐ion monitoring of both molecular and fragment ions, is the more sensitive mass‐selective method for the determination of the most toxic PCB congeners.

Toxic PCB Congeners and Organochlorine Pesticides in Italian Human Milk

Human milk from four major Italian cities was analyzed for individual congeners of polychlorinated biphenyls (PCB), DDT, DDE, hexachlorobenzene, and β-hexachlorocyclohexane. Minimum and maximum concentrations in milk from individual mothers for most compounds ranged between one order of magnitude below and above the mean value of all mothers. Good agreements were found between results from pooled samples and mean values of individual samples. No statistically significant difference between cities was found and the levels in milk from Italian mothers did not differ significantly from published levels from other parts of the world. Principal component analyses revealed that the PCB congener distribution pattern was very similar in all mothers, independent of location. Average concentrations in milk from the four cities were 19(±5) μg liter −1 total PCB or 3.2(±0.8) ng liter −1 toxicity equivalents according to the most conservative TCDD toxicity equivalent factors of PCBs proposed in the literature, 70(±18) μg liter −1 DDE, 4.5(±1.2) μg liter −1 DDT, 5.6(±1.9) μg liter −1 HCB, and 4.4(±1.7) μg liter −1 β-hexachlorocyclohexane.

Spatial and Temporal Variations in Chemical Contamination of American Eels, Anguilla rostrata, Captured in the Estuary of the St, Lawrence River

Levels of polychlorinated biphenyls (PCBs), mirex, and pesticides were 10–100 times higher in migratory adult American eels, Anguilla rostrata, sampled at Kamouraska, Quebec, in 1990 than in eels from an uncontaminated reference tributary; concentrations in eels within the estuary varied little among sites. In contrast, mercury levels were the same at estuarine and reference sites, suggesting natural sources or atmospheric deposition of mercury. Dioxins, furans, and polynuclear aromatic hydrocarbons were virtually absent at all sites. During the 7 wk of migration, levels of PCBs, mirex, and pesticides in eels increased, while mercury did not. Since 1982, levels of PCBs and mirex have declined by 68 and 56%, respectively, and the percentage of eels exceeding human health guidelines for PCBs and mirex was about twofold lower in 1990 than in 1982. Levels of other pesticides have also declined, except that dieldrin is unchanged since 1982. While chemical concentrations are declining, levels of specific, highly toxic PCB congeners are sufficiently high that eel consumption by beluga whales (Delphinapterus leucas) is still likely to be hazardous. The hazard to the eels themselves is unknown due to a scarcity of toxicity data, but the highest concentrations of chemicals were observed in gonads.