Evaluation of the effectiveness of different indicator PCBs to estimating total PCB concentrations in environmental investigations

Contaminant assessment of stranded and deceased beaked whales (Ziphiidae) on the New South Wales coast of Australia

Metal and organic pollutants are prominent marine contaminants that disperse widely throughout the environment. Some contaminants biomagnify, leaving long-lived apex predators such as cetaceans at risk of toxicity. Various tissues collected post-mortem from 16 Ziphiidae individuals that stranded on the New South Wales (NSW) coast, Australia, over ∼15 years were investigated for 16 metals/metalloids and 33 organic contaminants. Polychlorinated biphenyls (PCBs) and Dichlorodiphenyltrichloroethanes (DDTs) were commonly detected in blubber and liver tissues. Mercury, cadmium and silver exceeded reported toxicity thresholds in several individuals. The liver tissue of a Mesoplodon layardii specimen had the highest mercury (386 mg/kg dry weight). Liver tissue of a Mesoplodon grayi specimen had the highest silver concentration (19.7 mg/kg dry weight), and the highest cadmium concentration was in Ziphius cavirostris kidney (478 mg/kg dry weight). This study provides important new information for rare Ziphiidae species globally.

The catalytic hydro-dechlorination of 2, 4, 4' trichlorobiphenyl at mild temperatures and atmospheric pressure

IMPLICATION STATEMENT

The remediation need for polychlorinated biphenyls (PCBs) still remains long after their production ban around the world. The development of low cost methods is highly desirable, especially for developing countries, in response to the Stockholm Convention. In this study, the dechorination of a ubiquitously present PCB congener was studied using a catalytic hydro-dechlorination (HDC) method in low temperatures up to ~ 77°C and was able to achieve near 100% dechlorination in six hours. Results indicated that the HDC process can be performed under mild temperatures and atmospheric conditions and can be a potential solution to real world PCB contamination issues.

Is current generation of polychlorinated biphenyls exceeding peak production of the 1970s?

Polychlorinated biphenyls (PCBs) are man-made chemicals that were once widely produced as commercial mixtures for various industrial applications. PCBs were later recognized as environmental pollutants and health hazards, leading to their global phase-out and strict regulations on their production, use, and disposal. Most investigations on PCBs focus on measuring the specific PCBs present in commercial mixtures or marker compounds representing those mixtures. However, there are new sources of PCBs that are gaining more attention. These 'by-product PCBs' are inadvertently produced in certain chemical and product formulations. Our estimates show that U.S. legislation currently permits the generation of more by-product PCBs (~100 million lb. (~45,000 Tonnes) per year) than during peak commercial production of the 1970s (85 million lb. (~39,000 Tonnes) per year). These PCBs are currently going un-detected in most investigations. Therefore, they may be a posing a growing, unmonitored environmental and human health risk. Most people assume PCBs to be legacy pollutants from historically formulated commercial mixtures. However, our research suggests that due to the emergence of by-product PCBs they may need to be reconsidered as an emerging pollutant of concern.

Systematic investigation of organochlorine pesticides and polychlorinated biphenyls blood levels in Greek children from the Rhea birth cohort suggests historical exposure to DDT and through diet to DDE

The blood levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) have been thoroughly investigated in Greek children from the Rhea birth cohort study. This investigation aimed to assess exposure levels, explore their possible relationship with children's age and sex, and indicate potential sources of exposure. Exposure patterns and common sources of PCBs and OCPs were analyzed using bivariate and multivariate statistics. A total of 947 blood samples from study participants were analyzed for OCP and PCB exposure, with 375 samples collected at 4 years old, 239 at 6.5 years old, and 333 at 11 years old. Elevated levels of DDE were observed in 6.5-year-old children compared to corresponding levels in other European countries. Higher levels of DDE were found in 4-year-old children, with the lowest concentrations in the 11-year-old group. The DDT/DDE ratio was consistently less than 1 among all the examined subjects. These results indicate exposure to DDT and DDE both in utero and through breastfeeding and dietary intake. For the entire cohort population, the highest concentration was determined for PCB 28, followed by PCBs 138, 153, and 180. The sum of the six indicator PCBs implied low exposure levels for the majority of the cohort population. Spearman correlations revealed strong associations between PCBs and OCPs, while principal component analysis identified two different groupings of exposure. DDE exhibited a correlation with a series of PCBs (153, 156, 163, 180), indicating a combined OCP-PCB source, and an anticorrelation with others (52, 28, 101), implying a separate and competing source.

Quantifying 209 Polychlorinated Biphenyl Congeners in Silicone Wristbands to Evaluate Differences in Exposure among Demolition Workers

A social housing estate in Denmark was designated for demolition due to exceedance of guidance values for polychlorinated biphenyls (PCBs) in indoor air. Here, we deployed precleaned silicone wristbands (n = 46) among demolition workers of these contaminated buildings during single workdays while conducting various work tasks. We established a method to analyze all 209 PCBs in wristbands to identify prominent congeners of exposure and evaluate differences between tasks. Wristbands were extracted using microwave-assisted extraction and then concentrated for gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. Twenty-nine chromatographic peaks representing 37 congeners were detected in every wristband, and tetra-CBs were the dominant homologue group. PCB-66, -44, and -70 were the most abundant congeners measured in worker wristbands, none of which are included within the typical seven indicator or WHO 12 PCBs. Workers who cut PCB-containing sealants had wristbands with the highest PCB concentrations (geometric mean ∑209PCBs = 1963 ng/g wristband), which were followed by those handling concrete elements on the building roof. Additionally, wristbands captured a broader range of PCBs than has been previously measured in air and serum samples. Taken together, our results highlight the importance of total congener analysis in assessing current PCB exposure in demolition work and the utility of wristbands for assessing these exposures.

The residues and health risk assessment of polychlorinated biphenyls (PCBs) in Pheretima (an earthworm-derived traditional medicine) from southeastern China

Minimal research exists on polychlorinated biphenyl (PCB) exposure from traditional Chinese medicines (TCMs), despite their significant contributions to domestic and international health protection. This study is the first to investigate the levels, profiles, and health risks of PCB residue in Pheretima, a typical TCM produced from earthworm. Seventy-seven Pheretima samples from different regions of China were analyzed for 45 PCB congeners. PCBs were found in all samples exhibiting species-dependent discrepancies. ∑45PCBs was ranging from 0.532 to 25.2 µg/kg (mean 4.46 µg/kg), with CB-11 being the most abundant congener contributing 71.8% ± 10.8% to ∑45PCBs, followed by CB-47, which were all non-Aroclor congeners called unintentionally produced PCBs (UP-PCBs). The average estimated daily intake of ∑45PCBs, ∑7ID-PCBs (indicative polychlorinated biphenyls), and CB-11 were 0.71, 0.04, and 0.51 ng/kg bw/d, respectively. The ∑HQ of PCBs in Pheretima samples was 2.97 × 10-4-2.46 × 10-2 (mean 2.77 × 10-3, 95th 4.21 × 10-3), while the ∑RQ ranged from 1.19 × 10-8 to 2.88 × 10-6 (mean 4.87 × 10-7, 95th 2.31 × 10-6). These findings indicate that Pheretima ingestion does not pose significant non-carcinogenic risks. However, certain individual samples exhibit an acceptable level of potential risks, particularly when considering that PCBs are recognized as endocrine disruptors and classified as probable carcinogens. These results contribute to the safety evaluation of traditional medicines and suggest the potential use of Pheretima as a bioindicator for PCB pollution. It is advisable to monitor UP-PCBs as indicator congeners and gather additional toxicological data.

The association of exposure to polychlorinated biphenyls with lipid profile and liver enzymes in umbilical cord blood samples

Evidence on prenatal exposure to polychlorinated biphenyls (PCBs) and its effects on newborns and potential biological mechanisms is not well defined yet. Therefore, this study aimed to examine whether PCBs are associated with lipid profile and non-invasive markers of hepatocyte injuries in samples of blood obtained from the umbilical cord. This study included 450 mothers-newborn pairs. Umbilical levels of PCBs were measured using Gas Chromatography/Mass Spectrophotometry (GC/MS). Lipid profile including low-density lipoprotein (LDL-C), total cholesterol (TC), triglycerides (TG), and high-density lipoprotein (HDL-C), as well as liver enzymes i.e., alanine amino transferase (ALT), aspartate amino transferase (AST), γ-glutamyl-transferase (GGT) and alkaline phosphatase (ALP) were determined from umbilical cord blood samples. Quantile g-computation analysis was applied to evaluate the collective influence of PCBs on both lipid profiles and liver enzymes, along with the impact of lipid profiles on liver enzymes. Exposure to the mixture of PCBs was significantly associated with increases in ALP, AST, ALT, and GGT levels in cord blood samples, with increments of 90.38 U/L (95%CI: 65.08, 115.70, p < 0.01), 11.88 U/L (95%CI: 9.03, 14.74, p < 0.01), 2.19 U/L (95%CI:1.43, 2.94, p < 0.01), and 50.67 U/L (95%CI: 36.32, 65.03, p < 0.01), respectively. Additionally, combined PCBs exposure was correlated with significant increases in umbilical TG, TC, and LDL-C levels, with values of 3.97 mg/dL (95%CI: 0.86, 7.09, p = 0.01), 6.30 mg/dL (95%CI: 2.98, 9.61, p < 0.01), and 4.63 mg/dL (95%CI: 2.04, 7.23, p < 0.01) respectively. Exposure to the mixture of lipids was linked to elevated levels of AST and GGT in umbilical cord blood samples. Furthermore, a noteworthy mediating role of TC and LDL-C was observed in the association between total PCBs exposure and umbilical cord blood liver enzyme levels. Overall our findings suggested that higher levels of umbilical cord blood PCBs and lipid profile could affect liver function in newborns.

Levels and species-specific organochlorine accumulation in three shark species from the western Gulf of California with different life history traits

Organochlorine compounds (OCs), such as organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), remain ubiquitous in marine ecosystems despite their prohibition or restriction, posing a risk to marine wildlife and humans. Their accumulation in liver tissue and potential toxicity in three exploited shark species (the scalloped hammerhead, Sphyrna lewini; the Pacific sharpnose shark, Rhizoprionodon longurio; and the Pacific angel shark, Squatina californica) with different physiological and ecological features from the western Gulf of California (GC) were investigated. Forty of the 47 OCs analyzed were identified, evidencing a greater agricultural than industrial influence considering the high DDTs/PCBs ratios. The DDT group was the main contributor to ∑OCs in the three species, while hexa- and hepta-CBs dominated the PCB profiles. S. lewini (juveniles) and R. longurio (juveniles and adults) had similar and significantly (p < 0.05) higher ∑OCP concentrations than S. californica (juveniles and adults), which is attributed to their migration to other polluted regions of the gulf. The three species' ∑PCB levels (lipid weight) were comparable and considered low in comparison to those documented in prior studies conducted worldwide. No intraspecific differences were observed when comparing by sex, but OC concentrations were higher in larger individuals. S. lewini and R. longurio showed different OC bioaccumulation trends against size, while no relationship between size and ∑OC concentrations was observed in S. californica. All shark species' toxic equivalents (TEQs) were calculated from dioxin-like PCB concentrations and were far below the established TEQ fish thresholds. However, future research is needed regarding the possible PCB and OCP effects in elasmobranchs. This study provides the basis for monitoring organic contaminants in predatory sharks from the western GC. It also highlights the importance of further research on unintentionally produced organochlorine environmental levels and sources.

Strategy for Remediation of Polychlorinated Biphenyls-Contaminated Soil Through Redox Management Based on Electronegativity of the Contaminants

Literature review reveals that Persistent Organic Pollutants (POPs), such as polychlorinated biphenyls (PCBs), are electron deficient compounds due to the presence of highly electronegative groups. Hence, they are more amenable to anaerobic biodegradation rather than oxidative metabolism. However, the studies on PCBs bioremediation are more inclined towards aerobic treatment. Besides, the past studies are mainly centered on screening and application of PCB-degrading microorganisms. In our opinion the degradative capacity is already present in the native microflora, and choice of electron donor is of paramount importance for faster reductive metabolism of PCBs. In this study, the use of methanol as electron donor with cow dung as the general microbial inoculum resulted in high specific rate of degradation (0.0542-0.0637 /day) for high-chlorinated biphenyls. The % removal of PCBs ranged between 67.7 and 71.7%. It may be the first study on the application of methanol as a cheap electron donor for PCBs biodegradation without bioaugmentation with specifically selected microorganisms.

Use of a polymeric implant system to assess the neurotoxicity of subacute exposure to 2,2',5,5'-tetrachlorobiphenyl-4-ol, a human metabolite of PCB 52, in male adolescent rats

Polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) that ubiquitously exist in the environment. PCB exposure has been linked to cancer and multi-system toxicity, including endocrine disruption, immune inhibition, and reproductive and neurotoxicity. 2,2',5,5'-Tetrachlorobiphenyl (PCB 52) is one of the most frequently detected congeners in the environment and human blood. The hydroxylated metabolites of PCB 52 may also be neurotoxic, especially for children whose brains are still developing. However, it is challenging to discern the contribution of these metabolites to PCB neurotoxicity because the metabolism of PCB is species-dependent. In this study, we evaluated the subacute neurotoxicity of a human-relevant metabolite, 2,2',5,5'-tetrachlorobiphenyl-4-ol (4-52), on male adolescent Sprague Dawley rats, via a novel polymeric implant drug delivery system grafted subcutaneously, at total loading concentrations ranging from 0%, 1%, 5%, and 10% of the implant (w/w) for 28 days. Y-maze, hole board test, open field test, and elevated plus maze were performed on exposure days 24-28 to assess their locomotor activity, and exploratory and anxiety-like behavior. 4-52 and other possible hydroxylated metabolites in serum and vital tissues were quantified using gas chromatography with tandem mass spectrometry (GC-MS/MS). Our results demonstrate the sustained release of 4-52 from the polymeric implants into the systemic circulation in serum and tissues. Dihydroxylated and dechlorinated metabolites were detected in serum and tissues, depending on the dose and tissue type. No statistically significant changes were observed in the neurobehavioral tasks across all exposure groups. The results demonstrate that subcutaneous polymeric implants provide a straightforward method to expose rats to phenolic PCB metabolites to study neurotoxic outcomes, e.g., in memory, anxiety, and exploratory behaviors.

The biological invasion of an apex predator (Silurus glanis) amplifies PCB transfer in a large lake food web

Invasive species can affect food web structure possibly modifying the transfer of pollutants in ecosystems but this facet of biological invasion remains largely unexplored. We examined how trophic and ontogenetic characteristics of the invasive European catfish could differ from its native counterpart, the Northern pike, possibly resulting in the amplification of PCB transfer to the higher trophic levels in a large lake food web. The PCB contents of catfish and pike were on average low (Ʃ7 PCBi 42.4 ± 38.6 ng g-1 ww and 37.9 ± 49.4 ng g-1 ww respectively) and dominated by PCB153 (~35 % of the PCB contamination). Only the largest pike (126 cm) slightly exceeded the European sanitary threshold of 125 ng g-1 ww Ʃ6 PCBi-NDL. Both species increased in trophic position with body size while catfish had clearly higher littoral reliance than pike indicating they exploited complementary trophic niches. PCB biomagnification was identified only for catfish (PCB153, Ʃ7 PCBi) leading to trophic magnification factor of ~5. PCB ontogenetic bioaccumulation was pervasive for catfish (PCB101, PCB118, PCB153, PCB138 and Ʃ7 PCBi) and identified for pike only regarding PCB101. The derived size accumulation factors (~1.02) indicated a size-doubling PCB contamination of ~40 cm for catfish. This finding suggested that catfish would exceed the European sanitary threshold at body size larger than 168 cm possibly constraining their commercial exploitation. Our results highlighted that the invasive catfish was a littoral-oriented apex predator occupying an alternative trophic niche as compared to pike thereby modifying the lake food web structure that resulted in an enhancement of PCB transfer to higher trophic levels. The biomagnification and ontogenetic bioaccumulation of catfish underlined the impact of this biological invasion on the fate of PCB in the ecosystem. Finally, the remarkable inter-individual PCB contamination suggested variable inter-individual PCB exposure likely associated to localized hotspots of PCB contamination in the lake.

Deeper insights into the effects of low dietary levels of polychlorinated biphenyls on pig metabolism using gas chromatography-high resolution mass spectrometry metabolomics

Polychlorinated biphenyls (PCBs) are a class of contaminants of great concern, linked to the development of many chronic diseases. Adverse effects of PCBs have been documented in humans after accidental and massive exposure. However, little is known about the effect of chronic exposure to low-dose PCB mixtures, and studies regarding scattered lifetime exposures to non-dioxin-like (NDL)-PCBs are especially missing. In this work, serum samples from pigs chronically exposed through their diet during 22 days to Aroclor 1260 (i.e. a commercially available mixture of NDL-PCBs) underwent a metabolomics analysis using gas chromatography-high resolution mass spectrometry (GC-HRMS), with the objective to investigate the effect of exposure to low doses of NDL-PCBs (few ng/kg body weight (b.w.) per day). The study showed that the serum profiles of 84 metabolites are significantly altered by the administration of Aroclor 1260, of which 40 could be identified at level 1. The aggregate interpretation of the results of this study, together with the outcome of a previous one involving LC-HRMS profiling, provided a substantial and concise overview of the effect of low dose exposure to NDL-PCBs, reflecting the hepatotoxic and neurotoxic effects already reported in literature at higher and longer exposures. These results are intended to contribute to the debate on the current toxicological reference values for these substances.

Assessing Metabolic Differences Associated with Exposure to Polybrominated Biphenyl and Polychlorinated Biphenyls in the Michigan PBB Registry

BACKGROUND

Polybrominated biphenyls (PBB) and polychlorinated biphenyls (PCB) are persistent organic pollutants with potential endocrine-disrupting effects linked to adverse health outcomes.

OBJECTIVES

In this study, we utilize high-resolution metabolomics (HRM) to identify internal exposure and biological responses underlying PCB and multigenerational PBB exposure for participants enrolled in the Michigan PBB Registry.

METHODS

HRM profiling was conducted on plasma samples collected from 2013 to 2014 from a subset of participants enrolled in the Michigan PBB Registry, including 369 directly exposed individuals (F0) who were alive when PBB mixtures were accidentally introduced into the food chain and 129 participants exposed to PBB in utero or through breastfeeding, if applicable (F1). Metabolome-wide association studies were performed for PBB-153 separately for each generation and Σ PCB (PCB-118, PCB-138, PCB-153, and PCB-180) in the two generations combined, as both had direct PCB exposure. Metabolite and metabolic pathway alterations were evaluated following a well-established untargeted HRM workflow.

RESULTS

Mean levels were 1.75  ng / mL [standard deviation (SD): 13.9] for PBB-153 and 1.04  ng / mL (SD: 0.788) for Σ PCB . Sixty-two and 26 metabolic features were significantly associated with PBB-153 in F0 and F1 [false discovery rate (FDR) p < 0.2 ], respectively. There were 2,861 features associated with Σ PCB (FDR p < 0.2 ). Metabolic pathway enrichment analysis using a bioinformatics tool revealed perturbations associated with Σ PCB in numerous oxidative stress and inflammation pathways (e.g., carnitine shuttle, glycosphingolipid, and vitamin B9 metabolism). Metabolic perturbations associated with PBB-153 in F0 were related to oxidative stress (e.g., pentose phosphate and vitamin C metabolism) and in F1 were related to energy production (e.g., pyrimidine, amino sugars, and lysine metabolism). Using authentic chemical standards, we confirmed the chemical identity of 29 metabolites associated with Σ PCB levels (level 1 evidence).

CONCLUSIONS

Our results demonstrate that serum PBB-153 is associated with alterations in inflammation and oxidative stress-related pathways, which differed when stratified by generation. We also found that Σ PCB was associated with the downregulation of important neurotransmitters, serotonin, and 4-aminobutanoate. These findings provide novel insights for future investigations of molecular mechanisms underlying PBB and PCB exposure on health. https://doi.org/10.1289/EHP12657.

Serum polychlorinated biphenyl levels and circulating miRNAs in non-obese women with and without polycystic ovary syndrome

Introduction

Polychlorinated biphenyls (PCBs), organic lipophilic pollutants that accumulate through diet and increase with age, have been associated with polycystic ovary syndrome (PCOS) and shown to affect microRNA (miRNA) expression. This work aimed to determine if PCBs were associated with circulating miRNAs and whether there were any correlations with serum PCB/miRNA levels and hormonal changes.

Methods

29 non-obese PCOS and 29 healthy control women, with similar age and body mass index (BMI), had their serum miRNAs measured together with 7 indicator PCBs (PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, PCB180) using high resolution gas chromatography coupled with high resolution mass spectrometry.

Results

In the combined study cohort, four miRNAs (hsa-miR-139-5p, hsa-miR-424-5p, hsa-miR-195-5p, hsa-miR-335-5p) correlated with PCBs, but none correlated with metabolic parameters. hsa-miR-335-5p correlated with FSH. When stratified, 25 miRNAs correlated with PCBs in controls compared to only one (hsa-miR-193a-5p) in PCOS; none of these miRNAs correlated with the metabolic parameters of BMI, insulin resistance, or inflammation (C-reactive protein, CRP). However, of these 25 miRNAs in controls, hsa-miR-26a-5p, hsa-miR-193a-5p, hsa-miR-2110 and hsa-miR-195-5p positively correlated with luteinizing hormone (LH), hsa-miR-99b-5p and hsa-miR-146b-5p correlated with estradiol, hsa-miR-193a-5p correlated with progesterone, hsa-miR-195-5p correlated with follicle stimulating hormone (FSH), and hsa-miR-139-5p and hsa-miR-146b-5p negatively correlated with anti-müllerian hormone (AMH) (all p<0.05). hsa-miR-193a-5p in PCOS cases correlated with estradiol.

Conclusion

In this cohort of women, with no difference in age and BMI, and with similar PCB levels, the miRNAs correlating to PCBs associated with menstrual cycle factors in healthy menstruating controls versus the anovulatory PCOS subjects. The PCB-associated miRNAs did not correlate with non-reproductive hormonal and metabolic parameters. This suggests that PCB effects on miRNAs may result in changes to the hypothalamo-ovarian axis that may thus affect fertility.

Distribution, bioaccumulation, and health risk assessment of organochlorines across the riverine ecosystem of Punjab Province, Pakistan

This study was designed to assess the distribution of organochlorines (OCs) in fish species, their spatio-temporal variations, bioaccumulation potential, and associated human health risks via dietary intake. The levels of twenty-three organochlorine pesticides (OCPs) and thirty-five polychlorinated biphenyls (PCBs) were analyzed in six fish species collected from the riverine ecosystem of Punjab Province, Pakistan. The results indicated that the mean levels of Σ23OCPs were 74.1 ng/g ww and 184 ng/g ww, and for Σ35PCBs the levels were 38.8 ng/g ww and 74.8 ng/g ww in herbivorous and carnivorous fish species, respectively. The most abundant contaminants in all fish species were DDTs (65%) and HCHs (14%) among OCPs and heavier PCB congeners (62%) among PCBs. As for dioxin-like PCBs, the WHO toxic equivalency values (ng TEQ/g ww) were in the range of 0.21 (Cyprinus Carpio) to 2.38 (Rita Rita), exceeding the maximum allowable limit of 0.004 ng TEQ/g, ww by the European Commission. Spatio-temporal analysis indicated relatively higher OC levels in winter season with elevated concentrations in fish samples from industrial zone. The bioconcentration factor (L/kg) values ranged from 723 to 2773 for PCBs and 315 to 923 for OCPs in all fish species, with higher levels were reported in carnivorous species. The human health risk assessment at both 50th and 95th percentiles revealed the absence of any significant non-carcinogenic risk as calculated HR was less than 1. However, the critical carcinogenic risk was found to be associated for most of the contaminants, signifying the dietary exposure to OCPs and PCBs might pose the public health concern.

The first full-congener analysis of 209 polychlorinated biphenyls (PCBs) in the blubber of short-finned pilot whales (Globicephala macrorhynchus) stranded along the coast of Savu Island, Indonesia

Short-finned pilot whales (SFPW) are a group of cetaceans found globally in tropical and temperate seas and are commonly stranded in the group, but the reason behind their stranding is still unknown. No detailed information on the contamination status and bioaccumulation of halogenated organic compounds, including polychlorinated biphenyls (PCBs), in the SFPW from Indonesian waters has been reported. Therefore, we analyzed all 209 PCB congeners in the blubber of 20 SFPW specimens stranded along the coast of Savu Island, East Nusa Tenggara, Indonesia, in October 2012 to explain the status of contamination, congener profiles, potential risk of PCBs to cetaceans, and the determination of unintentionally produced PCBs (u-PCBs) in the blubber of SFPW. Concentrations of Σ209PCBs, Σ7in-PCBs, Σ12dl-PCBs, and Σ21u-PCBs were between 48 and 490 (mean:240 ± 140), 22-230 (110 ± 60), 2.6-38 (17 ± 10), and 1.0-13 (6.3 ± 3.7) ng g^-1 lipid weight (lw), respectively. Congener-specific profiles of PCBs among sex and estimated age groups were observed; relatively high proportions of tri-to penta-CBs in juveniles and highly chlorinated recalcitrant congeners in structure-activity groups (SAGs) in sub-adult females were noted. The estimated toxic equivalency (TEQs) value for dl-PCBs ranged from 2.2 to 60 TEQ_WHO pg/g lw, with juveniles containing high TEQ values than sub-adults and adults. Although the TEQs and concentrations of PCBs in SFPW stranded along Indonesian coasts were lower than those reported for similar whale species from other North Pacific regions, further research is needed to assess the long-term impact of halogenated organic pollutants on their survival and health.

Source apportionment of polychlorinated biphenyls (PCBs) using different receptor models: A case study on sediment from the Portland Harbor Superfund Site (PHSS), Oregon, USA

Multivariate modelling techniques are used by a wide variety of investigations in environmental chemistry. It is surprisingly rare for studies to show a detailed understanding of uncertainties created by modelling or how uncertainties in chemical analysis impact model outputs. It is common to use untrained multivariate models for receptor modelling. These models produce a slightly different output each time they are run. The fact that a single model can provide different results is rarely acknowledged. In this manuscript, we attempt to address this by investigating differences that can be generated using four different receptor models (NMF, ALS, PMF & PVA) to perform source apportionment of polychlorinated biphenyls (PCBs) in surface sediments from Portland Harbor. Results showed that models generally had a strong agreement and identified the same main signatures that represented commercial PCB mixtures, however, subtle differences were identified by; different models, same models but with a different number of end members (EM), and the same model with the same number of end members. As well as identifying different Aroclor-like signatures, the relative proportion of these sources also varied. Depending on which method is selected it may have a significant impact on conclusions of a scientific report or litigation case and ultimately, allocation on who is responsible for paying for remediation. Therefore, care must be taken to understand these uncertainties to select a method that produces consistent results with end members that can be chemically explained. We also investigated a novel approach to use our multivariate models to identify inadvertent sources of PCBs. By using a residual plot produced from one of our models (NMF) we were able to suggest the presence of approximately 30 different potentially inadvertently produced PCBs which account for 6.6 % of the total PCBs in Portland Harbor sediments.

Evaluation of a marine mammal status and trends contaminants indicator for European waters

Marine mammals are vulnerable to the bioaccumulation, biomagnification and lactational transfer of specific types of pollutants, such as industrial polychlorinated biphenyls (PCBs), due to their long-life spans, feeding at a high trophic level and unique fat stores that can serve as depots for these lipophilic contaminants. Currently, European countries are developing indicators for monitoring pollutants in the marine environment and assessing the state of biodiversity, requirements under both Regional Seas Conventions and European legislation. As sentinel species for marine ecosystem and human health, marine mammals can be employed to assess bioaccumulated contaminants otherwise below current analytical detection limits in water and lower trophic level marine biota. To aid the development of Regional Seas marine mammal contaminants indicators, as well as Member States obligations under descriptor 8 of the EU Marine Strategy Framework Directive, the current study aims to further develop appropriate methodological standards using data collected by the established UK marine mammal pollutant monitoring programme (1990 to 2017) to assess the trends and status of PCBs in harbour porpoises. Within this case study, temporal trends of PCB blubber concentration in juvenile harbour porpoises were analysed using multiple linear regression models and toxicity thresholds for the onset of physiological (reproductive and immunological) endpoints were applied to all sex-maturity groups. Mean PCB blubber concentrations were observed to decline in all harbour porpoise Assessment Units and OSPAR Assessment Areas in UK waters. However, a high proportion of animals were exposed to concentrations deemed to be a toxicological threat, though the relative proportion declined in most Assessment Units/Areas over the last 10 years of the assessment. Recommendations were made for improving the quality of the assessment going forward, including detailing monitoring requirements for the successful implementation of such an indicator.

Polychlorinated biphenyls (PCB) and polychlorinated dibenzo-para-dioxins and dibenzofurans (PCDD/F) in ambient air and deposition in the German background

PCDD/Fs (17 congeners and Σ tetra -to octachloro homologues) and 209 PCBs were investigated in monthly samples of ambient air (gas + particle phase) and atmospheric deposition at two background monitoring sites in Germany in 2018/19. In atmospheric deposition samples, PCDD/F congeners as well as certain PCBs were frequently below the method quantification limits whereas values for PCDD/F homologue groups could be quantified more often. Annual deposition averages for individual PCDD/Fs were between <0.1 μg/m²d and 6.7 μg/m²d. Averages for Σ TeCDD/F to OCDD/F homologue totals in deposition were about 11 pg/m²d and 19 pg/m²d. Total PCB deposition rates were about 1900 pg/m²d and 1550 pg/m²d. PCDD/F + PCB-deposition rates were below 1 pg WHO₂₀₀₅-TEQ/m²d on average. In ambient air, both substance groups were frequently observed. Annual concentration averages for individual PCDD/F were between 0.1 fg/m³ and 50 fg/m³. Average values for Σ TeCDD/F to OCDD/F homologue totals in ambient air were 283 fg/m³ and 162 fg/m³. Total PCB concentrations were about 50 pg/m³ at both sites. PCDD/F + PCB-TEQ values were lower than 5 fg WHO₂₀₀₅-TEQ/m³ on average. Besides the frequently studied dioxin-like PCBs and six indicator PCBs, the analysis of the 209 PCBs (166 separated PCB-peaks) enabled the identification and evaluation of additional PCBs that might be of environmental concern. Of 166 PCBs or PCB-coelutions, up to 144 were quantified in air samples and up to 94 in atmospheric deposition samples. In ambient air, some of these PCBs were observed at levels similar to or exceeding those of the six indicator PCBs. Important additional PCBs in ambient air were PCB 5 + 8, PCB 11, PCB 17, PCB 18, PCB 20 + 33, PCB 31, PCB 43 + 49, PCB 44, PCB 47 + 48 + 65 + 75, PCB 93 + 95 + 98 + 102, PCB 139 + 149, and PCB 151. The presence of these PCBs in atmospheric samples implies that by analysing only selected PCBs potentially important contaminants are overlooked.

Using a dynamic mass balance model to predict fate and transport of PCBs in a polluted boreal lake in Sweden

In 2013, a screening survey including fish (European perch, Perca fluviatilis) from 20 locations in the Stockholm region of Sweden indicated exceptionally high levels of PCBs (>450 ng ΣPCB₇/g ww) in Lake Oxundasjön. An extensive sampling program was launched to define the magnitude and area of impact of PCBs. Moreover, a dynamic mass balance model approach was applied to identify and quantify key transport processes and predict the long-term turnover of PCBs given various remediation scenarios. Based on the dating of sediment profiles, primary emissions of PCBs to Lake Oxundasjön have likely occurred from the end of the 1940s until 1980, reaching the lake via one of its tributaries. Presently, the main source of PCBs is diffusion from the lake sediments. From the lake outlet, >400 g ΣPCB₇/yr are transported to Lake Mälaren (the third largest lake in Sweden), supplying drinking water for parts of the Stockholm area. Remediation actions are necessary to reduce the PCB levels in fish below today's marketing limits and environmental quality standards. With natural recovery, our results indicate that the PCB levels in non-migratory fish from Lake Oxundasjön will be elevated for decades to come. The mass of PCBs stored in the lake sediments was estimated, and to our knowledge, Lake Oxundasjön is the most heavily PCB contaminated lake in Sweden. The system constitutes a unique opportunity to test and develop a mathematical mass balance model for PCBs, with substantial data acquired from different aquatic matrices. The model presented in the paper is applicable for risk assessments of PCBs, and the results contribute to the general understanding of the transport and turnover dynamics of PCBs in aquatic ecosystems.

A review of the mechanisms of by-product PCB formation in pigments, dyes and paints

There has been an increased awareness of paints and pigments as a source of by-product PCBs in the environment. The majority of existing work has focused only on reporting the presence of the main PCBs in different products with a specific focus on the most PCB congeners, PCB11 and PCB209. This gives the impression that only a handful of PCBs are found in paints. However, this is not the case. PCB profiles in paints and pigments can be just as complex as commercial technical mixtures. This review identified the presence of 149 different PCBs in paint samples. For reference, only 141 different PCBs have been reported in all of the 5 main commercial Aroclor formulations (A1016, A1242, A1248, A1254 (early & late) and A1260). The total PCB concentrations in some paint samples can be substantial, with concentrations as high as 919 mg kg^-1 reported in azo pigments. When trying to identify sources of PCBs in the environment, pigments, dyes and paints are often overlooked. In this manuscript, we have compiled congener profiles from 140 different samples from the available scientific literature and presented this in the supplementary information as valuable resource for others to use in source identification applications. We have also proposed detailed mechanisms for the formation of PCBs in pigments, dyes and paints. In many cases, the PCB congeners predicted by these mechanisms provide an excellent match for what has been observed in the scientific literature. We have also identified several additional classes of pigments that are expected to contain PCBs but have yet to be verified by experimental data.

An evidence map of polychlorinated biphenyl exposure and health outcome studies among residents of the Akwesasne Mohawk Nation

From the 1950s to the 1970s, three Superfund sites discharged polychlorinated biphenyl (PCB)-contaminated waste upstream of the Mohawk Nation at Akwesasne, resulting in PCB contamination of groundwater, soil, and sediment in the surrounding area. Given the persistence of PCBs in the environment and in human tissues, there are continued concerns regarding PCB exposures and the potential for adverse health effects in the community. We developed an evidence map of PCB research at Akwesasne in order to characterize the available data and to highlight potential research needs. Human health and exposure biomarker studies were identified from a literature search based on population, exposure, comparator, and outcome (PECO) criteria. Data extracted from references that met the inclusion criteria after full-text review included study characteristics (e.g., sample size, study design, sampling years), details on PCB measurements (e.g., analytical method, number of congeners analyzed, method detection limits), and results (e.g., PCB levels and summary of study conclusions). We identified 33 studies, conducted between 1986 and 2013, that examined PCB exposure characteristics and health effects in residents of the Akwesasne Mohawk Nation. Organizing this literature into an evidence map including information on study cohort, congener groupings, exposure biomarker characteristics, and health effects allowed us to identify research gaps and to suggest future research priorities for the community. We identified current PCB exposure levels and PCB source characterization as major uncertainties, both of which could be addressed by new studies of PCB concentrations in environmental media.

Occupational exposure to polychlorinated biphenyls (PCBs) in workers at companies in the Colombian electricity sector

Polychlorinated biphenyls (PCBs) comprise a family of 209 congeners that have low electrical conductivity and high thermal resistance due to their physicochemical properties and are thus widely used as dielectric oils, among other applications. Although PCBs are no longer used in dielectric oils in Colombia as of several years ago, electric transformers in Colombia might still contain PCBs, and workers might carry PCBs due to exposure from when they were still used in dielectric fluid. Thus, occupational exposure in Colombia to PCBs was evaluated by determining their concentrations in the blood plasma samples of 115 workers in the electricity sector . The sum of the six PCB indicators was between <LOD and 16.09 µg L^-1 (median: <0.10 µg L^-1, 95^th percentile: 1.30 µg L^-1), and the total concentration of PCBs calculated as PCB 138 + 153 + 180 × 1.7 was between <LOD and 3210.17 ng g^-1 lipids (median: <7.30 ng g^-1 , 95^th percentile: 392.79 ng g^-1). . One worker dedicated to transformer and capacitor maintenance activities presented a PCB value higher than the biological tolerance level of 15 µg L^-1. The findings of the present investigation revealed that workers in the electricity sector face chronic occupational exposure to PCBs; Finally, the results can help to improve health policies related to these contaminants in the country.

Assessment of PCBs in Surface Waters at Ultratrace Levels: Traditional Approaches and Biomonitoring (Lake Baikal, Russia)

This article presents the results of the assessment of PCB concentrations in surface waters at ultratrace level of concentrations. The assessment of PCB concentrations is based on data from monitoring PCBs in Baikal water within the conventional approach as well as from biomonitoring of PCBs using Baikal omul, Coregonus migratorius, Georgi, 1775 (C. migratorius), as a bioindicator. The time cycle of the monitoring covered the period from 2014 to 2021. The concentrations of PCBs in the water were estimated from the concentrations of seven indicator congeners: 28, 52, 101, 118, 138, 153, and 180, and from congeners of dioxin-like (dl) PCBs in the tissues of C. migratorius. The average value and the statistically significant range of the detected total concentrations (Ʃ7PCBs) in Baikal water were 0.30 and 0.26–0.34 ng/L, respectively. In the tissues of C. migratorius, the average value and the range of Ʃ7PCB concentrations were 5.6 and 4.9–6.3 ng/g (ww), respectively, and for dl-PCBs, 1.5 and 1.3–1.7 ng/g (ww), respectively. The total toxicity equivalent of the detected dl-PCBs was in the WHO-TEQ (2005) range from 0.03 to 0.06 pg/g (ww). The concentrations of Ʃ7PCBs in Baikal water and dl-PCBs in the tissues of C. migratorius corresponded to the concentration levels in the European alpine lakes and the tissues of S. trutta fish inhabiting these lakes.

Polychlorinated biphenyl (PCB) concentrations and profiles in marine mammals from the North Atlantic Ocean

Polychlorinated biphenyls (PCBs) can provide crucial information into the bioaccumulation and biomagnification of POPs in marine mammals. Muscle tissue samples were obtained for detailed PCB congener specific analysis of all 209 PCBs in 11 species of marine mammals stranded across the coast of the UK between 2010 and 2013. At least 145 PCB congeners were found in each individual. The highest concentrations of PCBs were recorded in a killer whale (318 mg/kg lipid) and the highest toxic equivalent in a Risso's dolphin (1687 pg/g TEQ₂₀₀₅ wet). Concentrations of PCBs in the majority of samples exceeded toxic thresholds (9 mg/kg lipid) for marine mammals, highlighting the health risk they face from PCB exposure. Many PCB profiles did not fit typical 'Aroclor' signatures, but instead indicated patterns of congeners that are resistant to biotransformation and elimination. However, this study identified a novel PCB signature in a sei whale that has not yet been previously observed in marine mammals. The whale had a PCB profile that included lighter and inadvertent PCB congeners such as PCB 11, suggesting that the main source of exposure was through atmospheric deposition, rather than terrestrial discharges. Seven subsamples were chosen for chiral analysis of PCB 95, 136 and 149. The enantiomer fractions (EFs) of C-PCBs 95 and 149 were non racemic suggesting there may be enantiomer selective metabolism in marine mammals. Although there has been a shift in the literature towards emerging pollutants, this study acts as a stark reminder that PCBs continue to pose a significant risk to wildlife.

A state-of-the-science review of polychlorinated biphenyl exposures at background levels: relative contributions of exposure routes

Exposure to polychlorinated biphenyls (PCBs) can occur through multiple routes and sources, including dietary intake, inhalation, dermal contact, and ingestion of dust and soils. Dietary exposure to PCBs is often considered the primary exposure route for the general population; however, recent studies suggest an increasing contribution from indoor inhalation exposure. Here, we aim to estimate the relative contribution of different PCB exposure pathways for the general population, as well as for select age groups. We conducted a targeted literature review of PCB concentrations in environmental media, including indoor and outdoor air, indoor dust, and soils, as well as of total dietary intake. Using the average concentrations from the studies identified, we estimated PCB exposure through different routes for the general population. In addition, we assessed exposure via environmental media for select age groups. We identified a total of 70 studies, 64 that provided background PCB concentrations for one or more of the environmental media of interest and 6 studies that provided estimates of dietary intake. Using estimates from studies conducted worldwide, for the general population, dietary intake of PCBs was the major exposure pathway. In general, our review identifies important limitations in the data available to assess population exposures, highlighting the need for more current and population-based estimates of PCB exposure, particularly for indoor air and dietary intake.

Enhanced plant-microbe remediation of PCBs in soil using enzyme modification technique combined with molecular docking and molecular dynamics

The study on the enhanced mechanisms of the enzymes involved in plant absorption, plant degradation, and microbial mineralization in the remediation of soils contaminated with polychlorinated biphenyls (PCBs) is of great significance for the application of plant-microbe combined remediation technique in PCB-contaminated soils. The present study first used a combination of molecular docking and molecular dynamics methods to calculate the effects of the plant absorption enzyme, plant degradation enzyme, and microbial mineralization enzyme on the PCBs in the soil environment. A multifunctional plant degradation enzyme was constructed with three functional roles of absorption, degradation, and mineralization using amino acid sequence recombination and site-directed mutagenesis to modify the template of plant degradation enzyme. Finally, using the Taguchi experimental design-assisted molecular dynamics simulation method, the suitable external environmental conditions of plant-microbe combined remediation of the PCB-contaminated soil were determined. In total, six multifunctional plant degradation enzymes were designed, which exhibited a significantly improved efficiency of PCB degradation. In comparison to the complex of plant absorption enzyme, plant degradation enzyme, and microorganism mineralization enzyme (6QIM-3GZX-1B85), the six multifunctional plant degradation enzymes exhibited significantly higher efficiency (2.10-2.38 times) in degrading the PCBs, with a maximum of 2.69 times under suitable external environmental conditions.

Non-dioxin-like polychlorinated biphenyl neurotoxic equivalents found in environmental and human samples

Non-dioxin like polychlorinated biphenyls (NDL PCB) are recognized neurotoxicants with implications on altered neurodevelopment and neurodegeneration in exposed organisms. NDL PCB neurotoxic relative potency schemes have been developed for a single mechanism, namely activity toward the ryanodine receptor (RyR), or combined mechanisms including, but not limited to, alterations of RyR and dopaminergic pathways. We compared the applicability of the two neurotoxic equivalency (NEQ) schemes and applied each scheme to PCB mixtures found in environmental and human serum samples. A multiple mechanistic NEQ predicts higher neurotoxic exposure concentrations as compared to a scheme based on the RyR alone. Predictions based on PCB ortho categorization, versus homologue categorization, lead to a higher prediction of neurotoxic exposure concentrations, especially for the mMOA. The application of the NEQ schemes to PCB concentration data suggests that PCBs found in fish from US lakes represent a considerable NEQ exposure to fish consuming individuals, that indoor air of schools contained high NEQ concentrations representing an exposure concern when inhaled by children, and that levels already detected in the serum of adults and children may contribute to neurotoxicity. With further validation and in vivo exposure data the NEQ scheme would help provide a more inclusive measure of risk presented by PCB mixtures.

Are concentrations of pollutants in sharks, rays and skates (Elasmobranchii) a cause for concern? A systematic review

This review represents a comprehensive analysis on pollutants in elasmobranchs including meta-analysis on the most studied pollutants: mercury, cadmium, PCBs and DDTs, in muscle and liver tissue. Elasmobranchs are particularly vulnerable to pollutant exposure which may pose a risk to the organism as well as humans that consume elasmobranch products. The highest concentrations of pollutants were found in sharks occupying top trophic levels (Carcharhiniformes and Lamniformes). A human health risk assessment identified that children and adults consuming shark once a week are exposed to over three times more mercury than is recommended by the US EPA. This poses a risk to local fishing communities and international consumers of shark-based products, as well as those subject to the widespread mislabelling of elasmobranch products. Wider screening studies are recommended to determine the risk to elasmobranchs from emerging pollutants and more robust studies are recommended to assess the risks to human health.

Persistent organic pollutants in sediments of the Wouri Estuary Mangrove, Cameroon: Levels, patterns and ecotoxicological significance

The anthropogenic impact in the Wouri Estuary Mangrove located in the rapidly developing urban area of Douala, Cameroon, Africa, was studied. A set of 45 Persistent Organic Pollutant were analysed in surficial mangrove sediments at 21 stations. Chlorinated Pesticides (CLPs), Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) have concentrations ranging from 2.2 - 27.4, and 83 - 544 ng/g, respectively. The most abundant CLPs were endosulfan, alachlor, heptachlor, lindane (γ-HCH) and DDT, which metabolites pattern revealed recent use. Selected PAHs diagnostic ratios show pyrolytic input predominantly. The sum of 7 carcinogenic PAHs (ΣC-PAHs) represented 30 to 50% of Total PAHs (TPAHs). According to effect-based sediment quality guidelines, the studied POPs levels imply low to moderate predictive biological toxicity. This study contributes to depict how far water resources are shifting within what is now termed the Anthropocene due to increasing local pressures in developing countries or African countries.

Associations between functional polychlorinated biphenyls in adipose tissues and prognostic biomarkers of breast cancer patients

BACKGROUND

Exposure to polychlorinated biphenyls (PCBs) has been shown to influence expression of some biomarkers that are predictive/prognostic for breast cancer. Therefore, our study was conducted to further investigating associations of different functional PCBs in adipose tissue with breast cancer prognostic biomarkers.

METHODS

Two hundred and five breast cancer patients were recruited in Shantou, China. Breast adipose tissues were collected during their resection surgery and levels of 7 PCB congeners were analyzed by gas chromatography-mass spectrometry (GC-MS). The PCB congeners were divided into 4 groups according to structure-activity. Socio-demographic, clinical and pathological information were obtained from questionnaire and digital medical records. Odds ratios (ORs) for associations between prognostic biomarkers and PCB levels (tertile 3 [T3], tertile 2 [T2] vs. tertile 1) were estimated from logistic regression models.

RESULTS

Most PCB congeners were detectable, with a highest level (22.06 ng/g lipid) of PCB153. As for estrogenic PCBs, increased PCB52 exposure was positively associated with PR expression (OR_T2 = 2.36, P_trend = 0.054), but higher PCB101 level was negatively associated with HER-2 (OR_T3 = 0.24, P_trend = 0.029) and tumor size (OR = 0.43). Limited dioxin-like PCB138 exposure was positively associated with ER (OR_T2 = 3.23, OR_T3 = 3.77, P_trend = 0.047) but negatively with Top-IIα expression (OR_T2 = 0.35, OR_T3 = 0.28, P_trend = 0.080). Higher PCB153 (CYP inducer) level was negatively associated with ER (OR_T2 = 0.32, OR_T3 = 0.19, P_trend = 0.038) but positively with Ki-67 expression (OR_T2 = 1.43, OR_T3 = 3.60, P_trend = 0.055). Higher neurotoxic PCB28 was positively associated with HER-2 (OR_T3 = 5.43, P_trend = 0.006) and tumor size (OR = 2.37). Moreover, total PCBs exposure was positively associated with VEGF-C (OR_T2 = 76.91, OR_T3 = 97.96, P_trend = 0.041) and tumor metastasis (OR = 2.25).

CONCLUSIONS

Different functional PCB congeners have different associations (both positive and negative) with breast cancer prognostic biomarkers, as well as tumor classification stage. Therefore, the development and aggressiveness of breast cancer may depend upon exposure to specific structure-activity of PCBs.

Polychlorinated biphenyls (PCBs) in water: method development and application to river samples from a populated tropical urban area

A method for the determination of polychlorinated biphenyls (PCBs) in water from urban rivers was implemented and validated. Extractions of dissolved and particulate PCBs were performed using solid-phase extraction and a pressurized solvent extraction system, respectively, and the analytes were identified and quantified by gas chromatography with tandem mass spectrometry in selected reaction monitoring mode with no further purification. The method was successfully developed for the determination of 41 PCBs with two precursor-product confirmations for each analyte. Low method detection limits (0.06-0.50 ng L^-1) and good precision (≤ 20%; n = 8) were obtained, as well a linear response of the calibration curve ranging from 1.0 to 50 ng L^-1. Method performance for real samples was tested with water collected weekly in triplicate during April 2018 from a eutrophic river in the city of Rio de Janeiro. The total (dissolved + particulate) PCB concentrations ranged from 2.17 to 5.29 ng L^-1, above the threshold for river water quality standards in Brazil. Graphical abstract.