Lower Polychlorinated Biphenyls Research Articles

Factors affecting the polychlorinated biphenyl signatures in serum of adults living in a highly polluted area in eastern Slovakia.

Over the years eastern Slovakia has been subject to consistent monitoring of high levels of polychlorinated biphenyls (PCBs) in both the environment and human populations attributed to the former production of PCBs at the Chemko Strážske plant. We aimed to investigate the extent to which dietary habits and residential location could affect the concentrations of PCBs in the blood serum samples of subjects. We enrolled 602 adult subjects from eastern Slovakia with an average age of 45.14 (±8.49) years. To determine the concentrations of 21 PCB congeners, we used solid phase extraction along with gas chromatography coupled with high-resolution mass spectrometry. Based on questionnaire data, the assessment of dietary habits and residential location was performed using score calculations and creating a map. Through principal component analysis, the 20 PCB congeners were classified into three groups: PC1, comprising highly chlorinated PCBs, and PC2 and PC3, consisting primarily of low chlorinated PCBs. Stepwise multivariate regression revealed positive and negative associations between PCB congeners represented by PC1-3 and scores related to the residential location and scores related to food consumption, respectively. We confirmed that levels of PCBs represented by PC1-3 increased with age. The geographical proximity to pollution sources proved to be a key contributing factor to the observed PCB levels in individuals residing in eastern Slovakia.

The Interplay of Persistent Organic Pollutants and Mediterranean Diet in Association With the Risk of Gestational Diabetes Mellitus.

Certain foods characterizing the alternate Mediterranean diet (aMED) are high in persistent organic pollutants (POPs), which are related to greater gestational diabetes mellitus (GDM) risk. We examined the associations of combined aMED and POP exposure with GDM. aMED score of 1,572 pregnant women was derived from food frequency questionnaires at early pregnancy within the U.S. Fetal Growth Study and plasma concentrations of 76 POPs, including organochlorine pesticides, polybrominated diphenyl ethers, polychlorinated biphenyls (PCBs), and per- and polyfluoroalkyl substances, were measured. Associations of combined aMED score and exposure to POPs with GDM risk were examined by multivariable logistic regression models. In 61 of 1,572 (3.88%) women with GDM, 25 of 53 included POPs had a detection rate >50%. Higher POP levels appeared to diminish potential beneficial associations of aMED score with GDM risk, with the lowest GDM risk observed among women with both high aMED score and low POP concentrations. Specifically, adjusted log-odds ratios of GDM risk comparing women with low PCB and high aMED score with those with low aMED score and high PCB concentrations was -0.74 (95% CI -1.41, -0.07). Inverse associations were also observed among women with low aMED score and high TransNo_chlor, PCB182_187, PCB196_203, PCB199, and PCB206. These associations were more pronounced among women with overweight or obesity. Pregnant women who consumed a healthy Mediterranean diet but had a low exposure to POP concentrations had the lowest GDM risk. Future endeavors to promote a healthy diet to prevent GDM may consider concurrent POP exposure.

Placental-brain axis in females detected within broadly impacted metabolic gene networks protects against prenatal PCB exposure.

Neurodevelopmental disorders have a strong male bias that is poorly understood. Placenta is a rich source of molecular information about environmental interactions with genetics (including biological sex), that affect the developing brain. We investigated placental-brain transcriptional responses in an established mouse model of prenatal exposure to a human-relevant mixture of polychlorinated biphenyls (PCBs). To understand sex, tissue, and dosage effects in embryonic (E18) brain and placenta by RNAseq, we used weighted gene correlation network analysis (WGCNA) to create correlated gene networks that could be compared across sex or tissue. WGCNA revealed that expression within most correlated gene networks was significantly and strongly associated with PCB exposures, but frequently in opposite directions between male-female and placenta-brain comparisons. In both WGCNA and differentially expressed gene analyses, male brain showed more PCB-induced transcriptional changes than male placenta, but the reverse pattern was seen in females. Furthermore, non-monotonic dose responses to PCBs were observed in most gene networks but were most prominent in male brain. The transcriptomic effects of low dose PCB exposure were significantly reversed by dietary folic acid supplementation across both sexes, but these effects were strongest in female placenta. PCB-dysregulated and folic acid-reversed gene networks were commonly enriched in functions in metabolic pathways involved in energy usage and translation, with female-specific protective effects enriched in PPAR, thermogenesis, glycerolipids, and O-glycan biosynthesis, as opposed to toxicant responses in male brain. The female protective effect in prenatal PCB exposures appears to be mediated by dose-dependent sex differences in transcriptional modulation of metabolism in placenta.

Occupational exposure to polychlorinated biphenyls: Development of neuropsychological functions over time

Occupational exposure to polychlorinated biphenyls (PCBs) continues to affect the health of exposed individuals until today. This study aims to expand previous findings by examining the development of neuropsychological functions of occupationally exposed participants over time. Especially verbal fluency and sensorimotor processing, found to be impaired in a previous study, were thus of particular interest. A total of 116 participants, who were part of the HELPcB cohort, underwent a neuropsychological test battery covering a multitude of cognitive functions. Plasma PCB levels were determined for each participant and classified as elevated or normal based on comparative values drawn from the German general population. Two structural equation models were then used to examine the effects of elevated PCB levels on neuropsychological functions. Results suggest that participants who displayed increased PCB plasma levels continued to show impairments in verbal fluency but not in sensorimotor processing after a second examination one year after the first measurement. Specifically, low chlorinated PCBs are associated with impaired verbal fluency, as compared to high-chlorinated and dioxin-like congeners. Alteration of dopamine concentration in response to PCB exposure might be a potential explanation of this result.

Unveiling the PCB biodegradation potential and stress survival strategies of resuscitated strain Pseudomonas sp. HR1

The exploration of resuscitated strains, facilitated by the resuscitation promoting factor (Rpf), has substantially expanded the pool of cultivated degraders, enhancing the screening of bio-inoculants for bioremediation applications. However, it remains unknown whether these resuscitated strains can re-enter the viable but non-culturable (VBNC) state and the specific stress conditions that trigger such a transition. In this work, the whole genome, and polychlorinated biphenyl (PCB)-degrading capabilities of a resuscitated strain HR1, were investigated. Notably, the focus of this exploration was on elucidating whether HR1 would undergo a transition into the VBNC state when exposed to low temperature and PCBs, with and without the presence of heavy metals (HMs). The results suggested that the resuscitated strain Pseudomonas sp. HR1 harbored various functional genes related to xenobiotic biodegradation, demonstrating remarkable efficiency in Aroclor 1242 degradation and strong resistance against stress induced by low temperature and PCBs. Nevertheless, when exposed to the combined stress of low temperature, PCBs, and HMs, HR1 underwent a transition into the VBNC state. This transition was characterized by significant decreases in enzyme activities and notable changes in both morphological and physiological traits when compared to normal cells. Gene expression analysis revealed molecular shifts underlying the VBNC state, with down-regulated genes showed differential expression across multiple pathways and functions, including oxidative phosphorylation, glycolysis, tricarboxylic acid cycle, amino acid metabolism, translation and cytoplasm, while up-regulated genes predominantly associated with transcription regulation, membrane function, quorum sensing, and transporter activity. These findings highlighted the great potential of resuscitated strains as bio-inoculants in bioaugmentation and shed light on the survival mechanisms of functional strains under stressful conditions, which should be carefully considered during bioremediation processes.

First evidence of legacy chlorinated POPs bioaccumulation in Antarctic sponges from the Ross sea and the South Shetland Islands

Antarctica is no longer pristine due to the confirmed presence of anthropogenic contaminants like Persistent Organic Pollutants (POPs). Benthic organisms are poorly represented in contamination studies in Antarctica although they are known to bioaccumulate contaminants. Sponges (Phylum Porifera) are dominant members in Antarctic benthos, both in terms of abundance and biomass, and are an important feeding source for other organisms, playing key functional roles in benthic communities. To the best of our knowledge, legacy chlorinated POPs such as polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and dichlorodiphenyltrichloroethane (DDT) and their metabolites have never been investigated in this Phylum in Antarctica. The aim of this work was to evaluate the bioaccumulation of PCBs, HCB, o,p’- and p,p’-DDT and their DDE and DDD isomers in 35 sponge samples, belonging to 17 different species, collected along the coast of Terra Nova Bay (Adèlie Cove and Tethys Bay, Ross Sea), and at Whalers Bay (Deception Island, South Shetland Islands) in Antarctica. Lipid content showed a significant correlation with the three pollutant classes. The overall observed pattern in the three study sites was ΣPCBs>ΣDDTs>HCB and it was found in almost every species. The ΣPCBs, ΣDDTs, and HCB ranged from 54.2 to 133.7 ng/g lipid weight (lw), from 17.5 to 38.6 ng/g lw and from 4.8 to 8.5 ng/g lw, respectively. Sponges showed contamination levels comparable to other Antarctic benthic organisms from previous studies. The comparison among sponges of the same species from different sites showed diverse patterns for PCBs only in one out of four cases. The concentration of POPs did not vary significantly among the three sites. The predominance of lower chlorinated organochlorines in the samples suggested that long-range atmospheric transportation (LRAT) could be the major driver of contamination as molecules with a high long range transport potential (e.g. low chlorinated PCBs, HCB) prevails on heavier ones.

High PCBs mineralization capability of a resuscitated strain Bacillus sp. LS1 and its survival in PCB-contaminated soil

Polychlorinated biphenyl (PCB)-degrading strains resuscitated by resuscitation promoting factor (Rpf) enlarged pure degraders to screen effective bio-inoculants for soil bioaugmentation. In this study, whole-genome analysis and PCB-degrading performance of a resuscitated strain LS1 were investigated. Importantly, the persistence and the physiological response of soil-inoculated LS1 were checked. The results indicate that the Bacillus sp. strain LS1 possessed the potential to degrade polycyclic aromatic compounds. LS1 exhibited better performance in degrading PCBs 18 and 52, but lower PCB 77 degradation capability. At PCBs concentration of 10 mg/L, the degradation efficiencies of PCBs 18, 52 and 77 within 96 h were 62.8 %, 59.6 % and 39.8 %, respectively. Combined the bph genes and metabolites detected, as well as the genes found in the genome, the abilities of LS1 for oxidative dehalogenation and mineralization of PCBs via HOPDA-benzoate-protocatechuate-β-ketoadipate pathway were determined. Notably, LS1 can still maintain survival and culturable state after inoculation into PCB-contaminated soil for 70 days. This is the first report to demonstrate the fate of resuscitated strain when used as soil bio-inoculant, which revealed the necessity and feasibility of using resuscitated strains to enhance bioremediation of PCB-contaminated soils.

Aerobic Bioaugmentation to Decrease Polychlorinated Biphenyl (PCB) Emissions from Contaminated Sediments to Air.

We conducted experiments to determine whether bioaugmentation with aerobic, polychlorinated biphenyl (PCB)-degrading microorganisms can mitigate polychlorinated biphenyl (PCB) emissions from contaminated sediment to air. Paraburkholderia xenovorans strain LB400 was added to bioreactors containing PCB-contaminated site sediment. PCB mass in both the headspace and aqueous bioreactor compartments was measured using passive samplers over 35 days. Time-series measurements of all 209 PCB congeners revealed a 57% decrease in total PCB mass accumulated in the vapor phase of bioaugmented treatments relative to non-bioaugmented controls, on average. A comparative congener-specific analysis revealed preferential biodegradation of lower-chlorinated PCBs (LC-PCBs) by LB400. Release of the most abundant congener (PCB 4 [2,2′-dichlorobiphenyl]) decreased by over 90%. Simulations with a PCB reactive transport model closely aligned with experimental observations. We also evaluated the effect of the phytogenic biosurfactant, saponin, on PCB bioavailability and biodegradation by LB400. Time-series qPCR measurements of biphenyl dioxygenase (bphA) genes showed that saponin better maintained bphA abundance, compared to the saponin-free treatment. These findings indicate that an active population of bioaugmented, aerobic PCB-degrading microorganisms can effectively lower PCB emissions and may therefore contribute to minimizing PCB inhalation exposure in communities surrounding PCB-contaminated sites.

Effect of PCBs Extracted from Offshore Sediment of South China Sea (Zhanjiang) on Histological Structure and Inflammation of Zebrafish Intestine

As ubiquitous environmental pollutants, polychlorinated biphenyls (PCBs) can cause significant health risks to various organisms, including humans. Meanwhile, PCBs exhibit various properties such as biological toxicity, high fat solubility, and accumulation in sediments and bioaccumulation in the food chain. In this study, the concentration of PCBs in Zhanjiang offshore sediment and the histopathological changes and the mRNA expression of cytokines in intestines of zebrafish (Danio rerio) exposed to environmentally relevant concentrations of PCBs were investigated. Among the six sites selected, PCB28 was found in the sediments of Lakeside Park (BHP) and Seashore Park (HBP), with concentrations of 35.0 and 27.0 μg/kg, respectively. On the other hand, PCB81 was discovered in the sediments of Jinsha Bay (JSW) with a total amount of 29.0 μg/kg. Adult zebrafish were exposed to different PCB concentrations through water, with control (no PCB exposure), positive control (PCB 81 at 10 μg/L), low (5 μg/L), medium (10 μg/L), and high (15 μg/L) PCB doses. The fish were euthanized on days 1, 3, 5, and 7. The intestinal epithelial cells of the zebrafish exposed to PCB extracts proved the dose-responsive lesions. With the increase of concentration and time (P < 0.05), the relative expression of IL-1β, IL-8, and TNF-α mRNA increased significantly. The results showed that intestinal lesions and inflammation were dependent on exposure dose.

Seasonal Air–Sea Exchange Dynamics of Polychlorinated Biphenyls Over the East China Marginal Seas: The Role of Water Masses in a Complex Coastal–Ocean Current System

AbstractContinental marginal seas are key reservoirs of anthropogenic pollutants. Understanding the physical processes controlling the air–sea exchange dynamics of polychlorinated biphenyls (PCBs) in the continental margin seas is crucial to constrain the contribution of PCBs from land and rivers to the ocean; however, the transport and fate of PCBs, and their controlling factors of air–sea exchange in the continental marginal seas still remain poorly understood. Here, we collected atmospheric and surface water samples from the Yellow Sea (YS) and East China Sea (ECS) in summer 2018 and winter 2019, and examined the PCB concentrations. The PCB air–sea gas exchange fluxes showed higher net volatilization in winter, largely due to southward movement of the strengthened Yellow Sea Coastal Current and Yangtze River Diluted Water with high PCB concentrations. Both the dissolved PCB concentrations in seawater and wind speed were the primary factors influencing the PCB air–sea exchange fluxes in winter. By contrast, weak PCB volatilization fluxes occurred when the Taiwan Warm Current with low PCB concentrations dominated in the ECS in summer. In comparison, the accumulation and release of some PCB homologues caused by a green tide in the coastal YS could lead to increased volatilization flux in summer. Our results suggest the transfer of air–sea exchange dynamics of PCBs from a water concentration‐dominated pattern to an environmental parameter‐controlled one due to their decreased land‐based input, and highlight the impact of water mass‐triggered changes (environmental parameters and algal blooms) on the air–sea exchange behavior of PCBs in the continental marginal sea.

PCB exposure is associated with reduction of endosymbionts in riparian spider microbiomes

Microbial communities, including endosymbionts, play diverse and critical roles in host biology and reproduction, but contaminant exposure may cause an imbalance in the microbiome composition with subsequent impacts on host health. Here, we examined whether there was a significant alteration of the microbiome community within two taxa of riparian spiders (Tetragnathidae and Araneidae) from a site with historical polychlorinated biphenyl (PCB) contamination in southern Ontario, Canada. Riparian spiders specialize in the predation of adult aquatic insects and, as such, their contaminant levels closely track those of nearby aquatic ecosystems. DNA from whole spiders from sites with either low or high PCB contamination was extracted, and spider microbiota profiled by partial 16S rRNA gene amplicon sequencing. The most prevalent shift in microbial communities we observed was a large reduction in endosymbionts in spiders at the high PCB site. The abundance of endosymbionts at the high PCB site was 63 % and 98 % lower for tetragnathids and araneids, respectively, than at the low PCB site. Overall, this has potential implications for spider reproductive success and food webs, as riparian spiders are critical gatekeepers of energy and material fluxes at the land-water interface.

Effect of sorbate stereochemistry on the sorption/desorption of polychlorinated biphenyls between natural soil and an aqueous solution

ABSTRACT This study aimed to investigate the effect of various sorbate physicochemical properties on the transportation, distribution, fate, and bioavailability as well as remediation of selected hydrophobic organic pollutants in the environment. The natural soil collected from uMngeni River of KwaZulu-Natal province of South Africa and non-ortho and ortho-substituted polychlorinated biphenyls (PCBs) were used in this study. Soil physicochemical properties were characterized and batch studies were carried out to determine the co-effects of PCB stereochemistry and concentration. The results indicated that non-ortho compounds (PCB 77) sorbed more to the soil, (approximately 67%) compared to the di-ortho substituted congener (PCB 52) with 59.5% sorption of the same homolog. The effect of initial concentrations of both non-ortho and ortho-substituted PCBs revealed that low initial PCB concentrations were mostly favored for the sorption while sorption was generally low for ortho-substituted PCBs at high concentration. It is noted from this study that the stereochemistry of PCB congeners may play a critical role in influencing the pollution indices in the environment. Therefore, ortho-substituted congeners may likely be susceptible to aqueous solubility and may likely lead to less affinity to sorb to soil/sediment, and if sorbed have potential to re-suspend back to surface water or leach to the groundwater easily thus posing more risk to aquatic organisms.

Spatial Variation in Contaminant Occurrence in Marine Fishes and Prawns from Coastal Tanzania.

There are limited data on organic contaminants in marine biota from coastal Tanzania, especially on the occurrence of industrial-use contaminants such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The present study, performed in 2018-2019 in coastal Tanzania and Zanzibar Island, aimed at assessing spatial variation in the occurrence of PCBs; brominated flame retardants (BFRs), including PBDEs; and organochlorine pesticides, including dichlorodiphenyltrichloroethane (DDT), among three locations that differ in degree of anthropogenic activity. Analyzed samples included edible tissues of marine fishes and prawns representing different trophic levels and habitats. The results indicate a mainland-island difference, with fishes and prawns collected on Zanzibar having significantly lower PCB and DDT concentrations but higher concentrations of hexachlorobenzene compared to the two mainland locations. The highest contaminant concentrations were found in fishes and prawns collected around central Dar es Salaam harbor, with median ΣPCBs ranging from 22.3 to 577 ng/g lipid weight and ΣDDTs from 22.7 to 501 ng/g lipid weight, suggesting local sources. Concentrations of PBDEs were similar among locations, suggesting more diffuse sources. None of the "newer-type" BFRs, including compounds introduced as replacements for PBDEs, were detected in the present study. Stable isotope values of carbon (δ13 C) and nitrogen (δ15 N) varied among locations, and the relationship between contaminants and δ15 N varied among locations and habitat (pelagic/demersal). Concentrations measured in the present study are below European guidelines for human consumption of fishes and prawns. However, industrial-use contaminants should be monitored in developing countries because they are contaminants of emerging concern as a result of increasing industrialization and global trade of used products and wastes. Environ Toxicol Chem 2022;41:321-333. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

PCBs in indoor air and human blood in Pittsfield, Massachusetts

Concentrations of polychlorinated biphenyls (PCBs) and three chlorinated pesticides were determined in serum from 21 residents of Pittsfield, MA and in the basement, living room and outdoor air of the 10 homes in which they lived. Median serum PCB levels were 4.2 ng/g, which are at least four times the average level in the US population, and consisted primarily of more highly chlorinated, persistent congeners. This reflects contamination with PCBs coming from the local General Electric facility. Median basement air concentration was 20.3 ng/m3, while the median living room air was 11.4 ng/m3 and median outdoor air concentration was 3.0 ng/m3. The PCB congeners detected in air were primarily low chlorinated (four and fewer) congeners, reflecting the greater volatility of PCBs with fewer chlorines. The congener pattern between basement and living room air showed a 95% correlation, while correlation with outdoor air was much less. While the congener pattern in air is very different from that of the PCB products used in Pittsfield (Aroclors 1254 and 1260), low chlorinated PCBs are detected in the vapor phase after air is blown across the commercial mixtures. The human serum samples did not show detectible levels of many of the congeners seen in the basement air samples, reflecting rapid metabolism of lower chlorinated PCBs by the human body. However, with continuous inhalation of indoor air, especially in the living room, the exposure to these non-persistent congeners may still have adverse health effects. Cellular studies of some of these non-persistent, low chlorinated congeners indicate that they are neurotoxic, mutagenic and cytotoxic. These results demonstrate the importance of consideration of inhalation of PCBs as a route of exposure, especially in indoor sites, and suggest that monitoring serum PCB concentration may not always provide a good measurement of exposure, especially to congeners that are relatively rapidly metabolized but have significant toxicity.

Dietary Acid Load, Serum Polychlorinated Biphenyl Levels, and Mortality Following Breast Cancer in the Long Island Breast Cancer Study Project.

Dietary acid load (DAL) may be associated with all-cause mortality (ACM) and breast cancer-specific mortality (BCM), and these associations may be modified by serum polychlorinated biphenyl (PCB) levels. Participants included 519 women diagnosed with first primary in situ or invasive breast cancer in 1996/1997 with available lipid-corrected PCB data. After a median of 17 years, there were 217 deaths (73 BCM). Potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores calculated from a baseline food frequency questionnaire estimated DAL. Cox regression estimated covariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between PRAL and NEAP with mortality. We evaluated effect measure modification by total serum PCB levels (>median vs. ≤median). PRAL quartile 4 versus quartile 1 was associated with an ACM HR of 1.31 (95%CI = 0.90–1.92). In the upper median of PCBs, ACM HRs were 1.43 (95%CI = 0.96–2.11) and 1.40 (95%CI = 0.94–2.07) for PRAL and NEAP upper medians, respectively. In the lower median of PCBs, the upper median of NEAP was inversely associated with BCM (HR = 0.40, 95%CI = 0.19–0.85). DAL may be associated with increased risk of all-cause mortality following breast cancer among women with high total serum PCB levels, but inversely associated with breast cancer mortality among women with low PCB levels.

Accumulation of polychlorinated biphenyls (PCB) associated with bottom sediments in larvae of Chironomus riparius Meigen

Patterns of bioaccumulation of polychlorinated biphenyls (PCBs) by chironomid larvae (Chironomus riparius Meigen) were studied under laboratory conditions. Larvae were maintained for 20 days, separately in two batches of natural bottom sediments sampled from Rybinsk Reservoir (Russia), each differing in PCB content (425.6 μg / kg or 24.8 μg / kg dry weight, respectively). The study revealed that chironomid larvae accumulated PCBs at levels comparable to the PCB content measured in sediments from each exposure. The bioaccumulation coefficient (1.11 and 1.59, respectively, as per dry weight for compared sediment batches) depended directly on the sum PCB content in sediments. At high sediment PCB content, the ratios of homologous groups of PCBs in larvae and sediment were identical and corresponded to the Aroclor 1254 congeners profile; at lower PCB content, pronounced differences were revealed. In larvae, the ratios of 3, 4, 5, and 6CB homologues were evenly distributed at levels of 20–34 %, while the 4CB homologues prevailed (47 %) in sediments. The content of the latter compounds in larvae was lower than in sediments, and higher for the other homologous groups. The study indicates selective bioaccumulation of various homologous groups of PCBs under conditions of low sediment PCB content.

Phytoremediation of PCB: contaminated Algerian soils using native agronomics plants.

Pot cultivation experiments were conducted to assess the phytoremediation potential of two local agronomic plants, namely Avena sativa and Vicia sativa. Several soils with long-standing contamination and different levels of Polychlorinated biphenyl (PCB) contamination were used for this study. The soil samples came from different regions of Algeria and had different physico-chemical parameters. We studied the influence of these parameters on remediation potential of the two tested plants. The removal rate of the seven PCBs (PCB 28, 52, 101, 138, 153, 156 and 180) was examined after 40 and 90days. The results showed that the presence of the plants reduced significantly the overall PCB content, ranging initially from 1.33-127.9mgkg1. After 90days, the forage plant Vicia sativa allowed us to reach an excess dissipation rate of 56.7% compared to the unplanted control for the most polluted soil. An average dissipation rate of 50% was obtained in the moderately polluted soil. The less contaminated soil had an excess dissipation rate of about 24% for both plants and a predominant dissipation of the low chlorinated PCBs.

Polluted porpoises: Generational transfer of organic contaminants in harbour porpoises from the southern North Sea

Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs) and hexachlorobenzene (HCB), bioaccumulate in marine ecosystems. Top predators contain high levels of POPs in their lipid-rich tissues, which may result in adverse effects on their reproductive, immune and endocrine functions. Harbour porpoises (Phocoena phocoena) are among the smallest of cetaceans and live under high metabolic demand, making them particularly vulnerable to environmental pressures. Using samples from individuals of all maturity classes and sexes stranded along the southern North Sea (n = 121), we show the generational transfer of PCBs, PBDEs and HCB from adults to foetuses. Porpoise placentas contained 1.3–8.2 mg/kg lipid weight (lw) Sum-17PCB, <dl-0.08 mg/kg lw Sum-17PBDE and 0.14–0.16 mg/kg lw HCB, which were similar to concentrations in foetus blubber. Contaminant levels increased significantly after birth through suckling. Milk samples contained 0.20–33.8 mg/kg lw Sum-17PCB, 0.002–0.51 mg/kg lw Sum-17PBDE and 0.03–0.21 mg/kg lw HCB. Especially lower halogenated and more toxic contaminants were transferred to calves, exposing them to high levels of contaminants early in life. Of all animals included in this study, 38.5% had PCB concentrations exceeding a threshold level for negative health effects (>9 mg/kg lw). This was particularly true for adult males (92.3% >9 mg/kg lw), while adult females had relatively low PCB levels (10.5% >9 mg/kg lw) due to offloading. Nutritional stress led to higher offloading in the milk, causing a greater potential for toxicity in calves of nutritionally stressed females. No correlation between PCB concentration and parasite infestation was detected, although the probability of a porpoise dying due to infectious disease or debilitation increased with increasing PCB concentrations. Despite current regulations to reduce pollution, these results provide further evidence of potential health effects of POPs on harbour porpoises of the southern North Sea, which may consequently increase their susceptibility to other pressures.

Leaching Rate of Polychlorinated Biphenyls (PCBs) from Marine Paint Chips

Polychlorinated biphenyls (PCBs) were added to certain marine vessel bottom paints as a plasticizer to improve the adhesion and durability of the paint. The most common PCB formulation used to amend such paints was Aroclor 1254. Fugitive Aroclor-containing paint chips generated from vessel maintenance and repair operations represent a potential source of PCB contamination to sediments. Limited published studies indicate that Aroclor-containing paint is largely inert and exhibits low PCB leaching into water; however, the rate and degree of leaching of PCBs from paint chips have not been directly studied. This laboratory-based study evaluated the rate and extent of leaching of PCBs from paint chips into freshwater. The results of this investigation demonstrate that the rate of PCB dissolution from paint chips decreased rapidly and exponentially over time. Based on this study, it is estimated that the rate of leaching of PCBs from paint chips would cease after approximately 3 years of exposure to water. When all leachable PCBs were exhausted, it is estimated that less than 1% of the mass of PCBs in the paint chips was amenable to dissolution. The results of this experiment suggest that Aroclor-containing paint chips found in sediments are likely short-term sources of dissolved-phase PCB to pore or surface waters and that the majority of the PCBs in paint chips remain in the paint matrix and unavailable for partitioning into water.Graphic

Population-level effects of polychlorinated biphenyl (PCB) exposure on highly vulnerable Indo-Pacific humpback dolphins from their largest habitat

While polychlorinated biphenyl (PCB)-related risks have been reported at the cellular, organ, and individual levels in some marine mammals, studies quantifying the PCB-associated population-level effects are limited. Here, we combined chemical analysis and individual-based model simulation to investigate the impact of PCBs on the Indo-Pacific humpback dolphin (sub)population from the Pearl River Estuary (PRE). An annual PCB accumulation rate of 0.29 ± 0.07 mg/kg lipid per year was estimated based on the measured age-specific male data as males continue to accumulate PCBs throughout their lifetime, without depurating contaminant loads. Using the Taiwan Strait dolphin population with low PCBs as a baseline, we compare our model simulations in PRE population to estimate relative population impacts of PCBs and other stressors. When using the current vital rates of the PRE dolphins which have been affected by PCBs and other stressors (e.g., underwater noise, prey limitation, etc.), our simulations revealed a substantial decline (8.1%) in the annual population growth rate (λ) of PRE metapopulation compared to baseline over the next 100 years. At the estimated PCB accumulation rate, the PCB-mediated effects on calf survival and immunity would cause a slight decline (0.9%) in λ relative to baseline. Our findings suggest a relatively limited impact of PCBs on the long-term survival of PRE dolphins among all stressors. However, it should be noted that even under model simulations where dietary PCBs were eliminated, humpback dolphins would still need a long time to reduce their PCB burdens to a relatively “safe” level through biological cycling. Considering that the baseline vital rates might also have been affected by PCBs and other stressors, our results are considered relative rather than absolute. This study provides a starting point for quantifying population-level consequences of contaminant exposure on humpback dolphins, although more efforts are needed to perfect this type of analysis.