Exposure and effects assessment of persistent organohalogen contaminants in arctic wildlife and fish

The associations of prenatal exposure to dioxins and polychlorinated biphenyls with neurodevelopment at 6 Months of age: Multi-pollutant approaches

BACKGROUND

Prenatal exposure to persistent organic pollutants, including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (DL-PCBs), and nondioxin-like PCBs (NDL-PCBs), has been hypothesized to have a detrimental impact on neurodevelopment. However, the association of prenatal exposure to a dioxin and PCB mixture with neurodevelopment remains largely inconclusive partly because these chemical levels are correlated.

OBJECTIVES

We aimed to elucidate the association of in utero exposure to a mixture of dioxins and PCBs with neurodevelopment measured at 6 months of age by applying multipollutant methods.

METHODS

A total of 514 pregnant women were recruited between July 2002 and October 2005 in the Sapporo cohort, Hokkaido Study on Environment and Children's Health. The concentrations of individual dioxin and PCB isomers were assessed in maternal peripheral blood during pregnancy. The mental and psychomotor development of the study participants' infants was evaluated using the Bayley Scales of Infant Development-2nd Edition (n = 259). To determine both the joint and individual associations of prenatal exposure to a dioxin and PCB mixture with infant neurodevelopment, Bayesian kernel machine regression (BKMR) and quantile-based g-computation were employed.

RESULTS

Suggestive inverse associations were observed between in utero exposure to a dioxin and PCB mixture and infant psychomotor development in both the BKMR and quantile g-computation models. In contrast, we found no association of a dioxin and PCB mixture with mental development. When group-specific posterior inclusion probabilities were estimated, BKMR suggested prenatal exposure to mono-ortho PCBs as the more important contributing factors to early psychomotor development compared with the other dioxin or PCB groups. No evidence of nonlinear exposure-outcome relationships or interactions among the chemical mixtures was detected.

CONCLUSIONS

Applying the two complementary statistical methods for chemical mixture analysis, we demonstrated limited evidence of inverse associations of prenatal exposure to dioxins and PCBs with infant psychomotor development.

Telomere length in relation to persistent organic pollutant exposure in white-tailed eagle (Haliaeetus albicilla) nestlings from Sweden sampled in 1995-2013

Telomeres are used as biomarkers of vertebrate health because of the link between their length, lifespan, and survival. Exposure to environmental stressors appears to alter telomere dynamics, but little is known about telomere length and persistent organic pollutant (POP) exposure in wildlife. The white-tailed eagle (WTE; Haliaeetus albicilla) is an avian top predator that accumulates high levels of POPs and may subsequently suffer adverse health effects. Here we study the Baltic WTE population that is well documented to have been exposed to large contaminant burdens, thereby making it a promising candidate species for analyzing pollutant-mediated effects on telomeres. We investigated telomere lengths in WTE nestlings (n = 168) over 19 years and examined legacy POP concentrations (organochlorines and polybrominated diphenyl ethers) in whole blood and serum as potential drivers of differences in telomere length. Although we detected significant year-to-year variations in telomere lengths among the WTE nestlings, telomere lengths did not correlate with any of the investigated POP concentrations of several classes. Given that telomere lengths did not associate with POP contamination in the Baltic WTE nestlings, we propose that other environmental and biological factors, which likely fluctuate on a year-to-year basis, could be more important drivers of telomere lengths in this population.

Impacts of endocrine disrupting chemicals on reproduction in wildlife and humans

Endocrine disrupting chemicals (EDCs) are ubiquitous in aquatic and terrestrial environments. The main objective of this review was to summarize the current knowledge of the impacts of EDCs on reproductive success in wildlife and humans. The examples selected often include a retrospective assessment of the knowledge of reproductive impacts over time to discern how the effects of EDCs have changed over the last several decades. Collectively, the evidence summarized here within reinforce the concept that reproduction in wildlife and humans is negatively impacted by anthropogenic chemicals, with several altering endocrine system function. These observations of chemicals interfering with different aspects of the reproductive endocrine axis are particularly pronounced for aquatic species and are often corroborated by laboratory-based experiments (i.e. fish, amphibians, birds). Noteworthy, many of these same indicators are also observed in epidemiological studies in mammalian wildlife and humans. Given the vast array of reproductive strategies used by animals, it is perhaps not surprising that no single disrupted target is predictive of reproductive effects. Nevertheless, there are some general features of the endocrine control of reproduction, and in particular, the critical role that steroid hormones play in these processes that confer a high degree of susceptibility to environmental chemicals. New research is needed on the implications of chemical exposures during development and the potential for long-term reproductive effects. Future emphasis on field-based observations that can form the basis of more deliberate, extensive, and long-term population level studies to monitor contaminant effects, including adverse effects on the endocrine system, are key to addressing these knowledge gaps.

Industrial Production of Organophosphate Flame Retardants (OPFRs): Big Knowledge Gaps Need to Be Filled?

Since the phase-out of traditional halogenated flame retardants (HFRs), interests of research are gradually being shifted to organophosphate flame retardants (OPFRs), and this can be reflected by the increasing number of publications on OPFRs year by year. Here, an extensive survey is conducted in an attempt to generate a list of OPFRs that are being produced in factories, and to investigate the annual production volume (APV). This survey suggests that at least n = 56 OPFR monomers and n = 62 OPFR mixtures are being currently produced in 367 factories around the world, and 201 out of them are in Mainland China. APV of OPFRs was estimated as 598,422 metric tons, and this number could be underestimated due to the limitation of available information. We also notice that current researches are confined to a limited number of OPFRs, especially for OP esters (OPEs), and other OPFRs with different structures from OPEs has been rarely studied. Based on all the collected datasets, we provide five recommendations for how to proceed with future research to more comprehensively understand the currently-produced OPFRs in the environment.

Bioaccumulation of PCBs, HCB and PAHs in the summer plankton from West Spitsbergen fjords

Concentrations of seven polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and twelve polycyclic aromatic hydrocarbons (PAHs) were examined in plankton collected in summer from different Arctic fjords (Hornsund, Kongsfjorden, Adventfjorden). The levels of all target contaminants in arctic protists have been analyzed for the first time. This is also the first report on PAH levels in arctic fjords zooplankton. ∑7 PCB, HCB and ∑12 PAH concentrations were up to 3.58 ng/g w.w., 0.28 ng/g w.w. and 249 ng/g w.w., respectively. Among the zooplankton species, the highest concentrations of the most analyzed contaminants were detected in Themisto abyssorum. This could be explained by the predatory feeding strategy of this species. The importance of diet was confirmed by the low concentrations of contaminants detected in the herbivorous copepod Calanus spp. Depending on contaminant, bioaccumulation occurred in 50 to 100% studied cases. Studies have shown significant biomagnification of PCBs and PAHs in zooplankton predator-prey pairs.

A baseline study of per- and polyfluoroalkyl substances (PFASs) in waterfowl from a remote Australian environment

Elevated concentrations of PFASs in the liver may pose a toxicological risk to bird species and humans that consume them. This study aimed to determine concentrations of 43 per- and polyfluoroalkyl substances (PFASs) in livers (n = 80) of Australian Shelducks (Tadorna tadornoides), Pacific Black Ducks (Anas superciliosa), and Teals (Anas sp.), as well as water and sediment from a remote Australian environment. Maximum concentrations of PFBA (1.9 ng L^-1), PFOA (1.7 ng L^-1) and PFOS (0.99 ng L^-1) in water were consistent with long-range atmospheric and oceanic transport. PFOS (30%) and PFNA (22%) were the most frequently detected PFASs in Australian Shelduck livers (0.31 ± 0.68 ng g^-1 ww and 0.16 ± 0.15 ng g^-1 ww respectively). Maximum concentrations of PFOS in Pacific Black Ducks (50%) and Teals (44%) was 2.4 ng g^-1 ww and 5.3 ng g^-1 ww respectively. While PFAS levels in birds from this remote environment were below current animal consumption guidelines, continued monitoring of this ecosystem is recommended to assess the human health risk of consumption of wild game.

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.

Integrated Genomic and Bioinformatics Approaches to Identify Molecular Links between Endocrine Disruptors and Adverse Outcomes

Exposure to Endocrine Disrupting Chemicals (EDC) has been linked with several adverse outcomes. In this review, we examine EDCs that are pervasive in the environment and are of concern in the context of human, animal, and environmental health. We explore the consequences of EDC exposure on aquatic life, terrestrial animals, and humans. We focus on the exploitation of genomics technologies and in particular whole transcriptome sequencing. Genome-wide analyses using RNAseq provides snap shots of cellular, tissue and whole organism transcriptomes under normal physiological and EDC perturbed conditions. A global view of gene expression provides highly valuable information as it uncovers gene families or more specifically, pathways that are affected by EDC exposures, but also reveals those that are unaffected. Hypotheses about genes with unknown functions can also be formed by comparison of their expression levels with genes of known function. Risk assessment strategies leveraging genomic technologies and the development of toxicology databases are explored. Finally, we review how the Adverse Outcome Pathway (AOP) has exploited this high throughput data to provide a framework for toxicology studies.

South polar skua (Catharacta maccormicki) as biovectors for long-range transport of persistent organic pollutants to Antarctica

Migratory bird species may serve as vectors of contaminants to Antarctica through the local deposition of guano, egg abandonment, or mortality. To further investigate this chemical input pathway, we examined the contaminant burdens and profiles of the migratory South polar skua (Catharacta maccormicki) and compared them to the endemic Adélie penguin (Pygoscelis adeliae). A range of persistent organic pollutants were targeted in muscle and guano to facilitate differentiation of likely exposure pathways. A total of 56 of 65 targeted analytes were detected in both species, but there were clear profile and magnitude differences between the species. The South polar skua and Adélie penguin muscle tissue burdens were dominated by p,p'-dichlorodiphenyldichloroethylene (mean 5600 ng g^-1 lw and 330 ng g^-1 lw respectively) and hexachlorobenzene (mean 2500 ng g^-1 lw and 570 ng g^-1 lw respectively), a chemical profile characteristic of the Antarctic and Southern Ocean region. Species profile differences, indicative of exposure at different latitudes, were observed for polychlorinated biphenyls (PCBs), with lower chlorinated congeners and deca-chlorinated PCB-209 detected in South polar Skua, but not in Adélie penguins. Notably, the more recently used perfluoroalkyl substances and the brominated flame retardants, hexabromocyclododecane and tetrabromobisphenol A, were detected in both species. This finding suggests local exposure, given the predicted slow and limited long-range environmental transport capacity of these compounds to the eastern Antarctic sector.

Diet-driven mercury contamination is associated with polar bear gut microbiota

The gut microbiota may modulate the disposition and toxicity of environmental contaminants within a host but, conversely, contaminants may also impact gut bacteria. Such contaminant-gut microbial connections, which could lead to alteration of host health, remain poorly known and are rarely studied in free-ranging wildlife. The polar bear (Ursus maritimus) is a long-lived, wide-ranging apex predator that feeds on a variety of high trophic position seal and cetacean species and, as such, is exposed to among the highest levels of biomagnifying contaminants of all Arctic species. Here, we investigate associations between mercury (THg; a key Arctic contaminant), diet, and the diversity and composition of the gut microbiota of polar bears inhabiting the southern Beaufort Sea, while accounting for host sex, age class and body condition. Bacterial diversity was negatively associated with seal consumption and mercury, a pattern seen for both Shannon and Inverse Simpson alpha diversity indices (adjusted R² = 0.35, F_1,18 = 8.00, P = 0.013 and adjusted R² = 0.26, F_1,18 = 6.04, P = 0.027, respectively). No association was found with sex, age class or body condition of polar bears. Bacteria known to either be involved in THg methylation or considered to be highly contaminant resistant, including Lactobacillales, Bacillales and Aeromonadales, were significantly more abundant in individuals that had higher THg concentrations. Conversely, individuals with higher THg concentrations showed a significantly lower abundance of Bacteroidales, a bacterial order that typically plays an important role in supporting host immune function by stimulating intraepithelial lymphocytes within the epithelial barrier. These associations between diet-acquired mercury and microbiota illustrate a potentially overlooked outcome of mercury accumulation in polar bears.

Moving forward in microplastic research: A Norwegian perspective

Given the increasing attention on the occurrence of microplastics in the environment, and the potential environmental threats they pose, there is a need for researchers to move quickly from basic understanding to applied science that supports decision makers in finding feasible mitigation measures and solutions. At the same time, they must provide sufficient, accurate and clear information to the media, public and other relevant groups (e.g., NGOs). Key requirements include systematic and coordinated research efforts to enable evidence-based decision making and to develop efficient policy measures on all scales (national, regional and global). To achieve this, collaboration between key actors is essential and should include researchers from multiple disciplines, policymakers, authorities, civil and industry organizations, and the public. This further requires clear and informative communication processes, and open and continuous dialogues between all actors. Cross-discipline dialogues between researchers should focus on scientific quality and harmonization, defining and accurately communicating the state of knowledge, and prioritization of topics that are critical for both research and policy, with the common goal to establish and update action plans for holistic benefit. In Norway, cross-sectoral collaboration has been fundamental in supporting the national strategy to address plastic pollution. Researchers, stakeholders and the environmental authorities have come together to exchange knowledge, identify knowledge gaps, and set targeted and feasible measures to tackle one of the most challenging aspects of plastic pollution: microplastic. In this article, we present a Norwegian perspective on the state of knowledge on microplastic research efforts. Norway's involvement in international efforts to combat plastic pollution aims at serving as an example of how key actors can collaborate synergistically to share knowledge, address shortcomings, and outline ways forward to address environmental challenges.

The mechanism of apoptosis of Chlamys farreri hemocytes under benzopyrene stress in vitro

Hemocytes are critical to the immune defense system of bivalves, and polycyclic aromatic hydrocarbons (PAHs) can mediate the immunity of bivalves by affecting the apoptosis of hemocytes. However, the underlying mechanism is still unclear. Chlamys farreri, as an important economic bivalve, was selected as the research subject for this experimentation. The hemocytes were exposed to typical PAHs-benzopyrene (B[a]P) in vitro to explore the apoptosis mechanism through detecting oxidative stress and oxidative damage-related indicators, apoptosis pathway factors, and apoptosis rate within 24 h. The results showed that the reactive oxygen species (ROS) and benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE) content in hemocytes increased significantly under B[a]P exposure, while antioxidant genes, glutathione peroxidase content and total antioxidant capacity all showed a trend of first rising and subsequent falling. B[a]P also caused serious damage to DNA and lysosomal membrane stability. The proapoptotic factors genes in the mitochondrial apoptosis pathway were significantly up-regulated, and the anti-apoptotic gene Bcl-2 was significantly down-regulated. Besides, mitochondrial membrane potential stability was significantly reduced and caspase 9 enzyme activity was significantly improved with the B[a]P stimulation. The factors of death receptor pathway were also significantly up-regulated by B[a]P. Moreover, the expression levels of Mitogen-Activated Protein Kinases were also induced. The gene expression and enzyme activity of the caspase 3 and the apoptosis rate were significantly increased under B[a]P exposure. In conclusion, these results indicated that ROS was induced by B[a]P, and further triggered the oxidative stress and oxidative damage in hemocytes. B[a]P induced hemocyte apoptosis was mediated by both mitochondrial apoptosis pathway and death receptor apoptosis, and the activation of mitochondrial apoptosis pathway was affected by ROS. In addition, BPDE and MAPKs may play important roles in the B[a]P-mediated apoptosis pathway. This study deepens understanding of the apoptosis pathway and the immunotoxicity mechanism in bivalves hemocytes stimulated by persistent organic pollutants.

Using Transcriptomics and Metabolomics to Understand Species Differences in Sensitivity to Chlorpyrifos in Japanese Quail and Double-Crested Cormorant Embryos

Modern 21st-century toxicity testing makes use of omics technologies to address critical questions in toxicology and chemical management. Of interest are questions relating to chemical mechanisms of toxicity, differences in species sensitivity, and translation of molecular effects to observable apical endpoints. Our study addressed these questions by comparing apical outcomes and multiple omics responses in early-life stage exposure studies with Japanese quail (Coturnix japonica) and double-crested cormorant (Phalacrocorax auritus), representing a model and ecological species, respectively. Specifically, we investigated the dose-dependent response of apical outcomes as well as transcriptomics and metabolomics in the liver of each species exposed to chlorpyrifos, a widely used organophosphate pesticide. Our results revealed a clear pattern of dose-dependent disruption of gene expression and metabolic profiles in Japanese quail but not double-crested cormorant at similar chlorpyrifos exposure concentrations. The difference in sensitivity between species was likely due to higher metabolic transformation of chlorpyrifos in Japanese quail compared to double-crested cormorant. The most impacted biological pathways after chlorpyrifos exposure in Japanese quail included hepatic metabolism, oxidative stress, endocrine disruption (steroid and nonsteroid hormones), and metabolic disease (lipid and fatty acid metabolism). Importantly, we show consistent responses across biological scales, suggesting that significant disruption at the level of gene expression and metabolite profiles leads to observable apical responses at the organism level. Our study demonstrates the utility of evaluating effects at multiple biological levels of organization to understand how modern toxicity testing relates to outcomes of regulatory relevance, while also highlighting important, yet poorly understood, species differences in sensitivity to chemical exposure. Environ Toxicol Chem 2021;40:3019-3033. © 2021 SETAC.

Exposure to legacy and novel perfluoroalkyl substance disturbs the metabolic homeostasis in pregnant women and fetuses: A metabolome-wide association study

BACKGROUND

Perfluoroalkyl substances (PFASs) exist extensively and several of these have been verified to be toxic. Prenatal exposure to PFASs has attracted much attention. Metabolome-wide association analyses can be used to explore the toxicity mechanisms of PFASs by identifying associated biomarkers.

OBJECTIVES

To evaluate associations between the metabolites in maternal and cord serum and internal exposure to several common PFASs.

METHODS

Paired maternal and cord serum samples were collected from 84 pregnant women who gave birth between 2015 and 2016. Seven legacy and two novel PFASs were measured. A nontarget metabolomic method and an iterative metabolite annotation based on metabolic pathways were applied to characterize the metabolic profiles. Linear regression adjusted with the false discovery rate and covariates was used to indicate the associations.

RESULTS

A total of 279 features in maternal serum and 338 features in cord serum were identified as metabolites associated with PFAS exposure. Perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS) were two PFASs associated with more metabolites, while the two novel chlorinated polyfluorinated ether sulfonic acids (Cl-PFESAs) showed less relevance to the metabolome. With pathway enrichment analysis, we found that three fatty acid metabolisms and retinol metabolism were correlated with PFAS exposure in maternal blood, and that sterol metabolism showed the correlation in both maternal serum and cord serum.

CONCLUSIONS

We identified metabolites and pathways in pregnant women and fetuses associated with the exposure to several PFAS, indicating a promising application for metabolome-wide association studies. Additional research is needed to confirm causation.

Organochlorine pesticides and NDL-PCBs in wild boars from flatland region with intensive agricultural activities

The objective of this study was to analyse the content of OHCs and NDL-PCBs in wild boar population living in densely populated flatland region with intensive agricultural production. A total of 82 liver samples were analysed by GC-MS method, revealing the presence of minimum one residue in the liver of the majority of animals (92.7%). Most commonly detected residues included ∑ HCH (64.6%), ∑endrin (56.1%) and ∑dieldrin (32.3%). Mean concentrations were in the range ∑endrin > ∑dieldrin > ∑HCH > ∑NDL-PCB > ∑DDT > ∑CHL > ∑endosulfan > methoxychlor. The dominant compound within the total content of NDL-PCBs was PCB 153 (76%). The assessment of daily intake and determination of Health Index indicated that in 6.1% of the samples the consumption of one single portion of wild boar liver would be harmful to human health due to the presence of ∑endrin or NDL-PCBs.

Within and between breeding-season changes in contaminant occurrence and body condition in the Antarctic breeding south polar skua

The Antarctic ecosystem represents a remote region far from point sources of pollution. Still, Antarctic marine predators, such as seabirds, are exposed to organohalogen contaminants (OHCs) which may induce adverse health effects. With increasing restrictions and regulations on OHCs, the levels and exposure are expected to decrease over time. We studied south polar skua (Catharacta maccormiciki), a top predator seabird, to compare OHC concentrations measured in whole blood from 2001/2002 and 2013/2014 in Dronning Maud Land. As a previous study found increasing organochlorine concentrations with sampling day during the 2001/2002 breeding season, suggesting dietary changes, we investigated if this increase was repeated in the 2013/2014 breeding season. In addition to organochlorines, we analyzed hydroxy-metabolites, brominated contaminants and per- and polyfluoroalkyl substances (PFAS) in 2013/2014, as well as dietary descriptors of stable isotopes of carbon and nitrogen, to assess potential changes in diet during breeding. Lipid normalized concentrations of individual OHCs were 63%, 87% and 105% higher for hexachlorobenzene (HCB), 1,1-dichloro-2,2-bis (p-chlorophenyl)ethylene (p,p'-DDE), and ∑Polychlorinated biphenyls (PCBs), respectively, in 2013/2014 compared to 2001/2002. South polar skuas males in 2013/2014 were in poorer body condition than in 2001/2002, and with higher pollutant levels. Poorer body condition may cause the remobilization of contaminants from stored body reserves, and continued exposure to legacy contaminants at overwintering areas may explain the unexpected higher OHC concentrations in 2013/2014 than 2001/2002. Concentrations of protein-associated PFAS increased with sampling day during the 2013/2014 breeding season, whereas the lipid-soluble chlorinated pesticides, PCBs and polybrominated diphenyl ether (PBDEs) showed no change. OHC occurrence was not correlated with stable isotopes. The PFAS biomagnification through the local food web at the colony should be investigated further.

Effects of Diesel, Heavy Metals and Plastics Pollution on Penguins in Antarctica: A Review

Simple Summary

Antarctica is contaminated by anthropogenic pollution. Due to the persistent low temperatures, the toxic impacts of pollution to the environment can be extensive. The severity of the effects varies according to the animal species, chemical type and level of exposure. Penguins are at major risk as they are the most prominent group of animals in Antarctica. This review highlights the background of penguins in Antarctica, the anthropogenic pollution and cases, as well as the toxic effects of diesel, heavy metals and microplastics toward penguins. A bibliometric analysis is also included.

Abstract

Antarctica is a relatively pristine continent that attracts scientists and tourists alike. However, the risk of environmental pollution in Antarctica is increasing with the increase in the number of visitors. Recently, there has been a surge in interest regarding diesel, heavy metals and microplastics pollution. Contamination from these pollutants poses risks to the environment and the health of organisms inhabiting the continent. Penguins are one of the most prominent and widely distributed animals in Antarctica and are at major risk due to pollution. Even on a small scale, the impacts of pollution toward penguin populations are extensive. This review discusses the background of penguins in Antarctica, the anthropogenic pollution and cases, as well as the impacts of diesel, heavy metals and microplastics toxicities on penguins. The trends of the literature for the emerging risks of these pollutants are also reviewed through a bibliometric approach and network mapping analysis. A sum of 27 articles are analyzed on the effects of varying pollutants on penguins in Antarctica from 2000 to 2020 using the VOSviewer bibliometric software, Microsoft Excel and Tableau Public. Research articles collected from the Scopus database are evaluated for the most applicable research themes according to the bibliometric indicators (articles, geography distribution, annual production, integrated subject areas, key source journals and keyword or term interactions). Although bibliometric studies on the present research theme are not frequent, our results are sub-optimal due to the small number of search query matches from the Scopus database. As a result, our findings offer only a fragmentary comprehension of the topics in question. Nevertheless, this review provides valuable inputs regarding prospective research avenues for researchers to pursue in the future.

Impact of broad-spectrum pesticides used in the agricultural and forestry sector on the pesticide profile in wild boar, roe deer and deer and risk assessment for venison consumers

The present work is the first extensive study of large-scale pesticides research in wild animals. The investigation covered three game species: wild boar (n = 42), roe deer (n = 79) and deer (n = 15) collected from north-eastern Poland. To characterize the 480 pesticides in muscle samples, LC-GC-MS/MS techniques were used. A total of 28 compounds were detected: 5 neonicotinoids, 6 organochlorine and 5 other insecticides, 9 fungicides and 4 herbicides, in the range of 0.1-85.3 ng g^-1. Over four hundred detections were done. The highest mean concentrations were as follows: anthraquinone (85.3 ng g^-1) > DDT-p,p' (4.6 ng g^-1) > imidacloprid (4.3 ng g^-1) > permethrin (3.6 ng g^-1) > thiacloprid (2.8 ng g^-1). DDT and metabolites were the most frequently detected, followed by acetamiprid, tebuconazole, clothianidin and imidacloprid. Overall, 92% samples with residues were recorded, including 100% of wild boar, 88% of roe deer and 86% of deer. More than one pesticide (up to 9) was found in over 73% of the tested samples. The estimated chronic and acute risk to consumers of venison were very low (below 1% ADI and ARfD). This interdisciplinary study may be helpful for estimating ecological risk to wild animals and risk to consumers of wild animal products, and also as a source of biomonitoring data.

Application and Evaluation of Novel Chromatographic Techniques to Detect and Quantitate 108 Pesticides and Metabolites in Muscle Samples From Wild Birds of Prey

The application and evaluation of highly efficient chromatographic techniques with tandem mass spectrometry for the detection and quantitation of 108 pesticides and metabolites, some considered persistent organic pollutants, was performed in muscle samples obtained from 25 birds of prey belonging to the families Accipitridae, Falconidae, and Strigidae presented dead in 2013 to Grupo de Rehabilitación de la Fauna Autóctona y su Hábitat, in Madrid, Spain. Pesticides with prohibited use were detected at high concentrations in the muscle samples analyzed. Based on its high sensitivity to detect pesticides in muscle, the described chromatographic techniques with tandem mass spectrometry should be considered an alternative testing methodology to those commonly used for routine application in ecotoxicological forensic research.

Long-Range Transport, Trophic Transfer, and Ecological Risks of Organophosphate Esters in Remote Areas

Organophosphate esters (OPEs) have been a focus in the field of environmental science due to their large volume production, wide range of applications, ubiquitous occurrence, potential bioaccumulation, and worrisome ecological and health risks. Varied physicochemical properties among OPE analogues represent an outstanding scientific challenge in studying the environmental fate of OPEs in recent years. There is an increasing number of studies focusing on the long-range transport, trophic transfer, and ecological risks of OPEs. Therefore, it is necessary to conclude the OPE pollution status on a global scale, especially in the remote areas with vulnerable and fragile ecosystems. The present review links together the source, fate, and environmental behavior of OPEs in remote areas, integrates the occurrence and profile data, summarizes their bioaccumulation, trophic transfer, and ecological risks, and finally points out the predominant pollution burden of OPEs among organic pollutants in remote areas. Given the relatively high contamination level and bioaccumulation/biomagnification behavior of OPEs, in combination with the sensitivity of endemic species in remote areas, more attention should be paid to the potential ecological risks of OPEs.

Maternal exposure to a human based mixture of persistent organic pollutants (POPs) affect gene expression related to brain function in mice offspring hippocampus

Male and female mice pups were exposed to a low and high dose of a human relevant mixture of persistent organic pollutants (POPs) during pregnancy and lactation. Most compounds detected in the dams were found in offspring brains. The mice offspring exhibited changed expression of hippocampal genes involved in cognitive function (Adora2a, Auts2, Crlf1, Chrnb2, Gdnf, Gnal, Kcnh3), neuroinflammation (Cd47, Il1a), circadian rhythm (Per1, Clock), redox signalling (Hmox2) and aryl hydrocarbon receptor activation (Cyp1b1). A few genes were differentially expressed in males versus females. Mostly, similar patterns of gene expression changes were observed between the low and high dose groups. Effects on learning and memory function measured in the Barnes maze (not moving, escape latency) were found in the high dose group when combined with moderate stress exposure (air flow from a fan). Mediation analysis indicated adaptation to the effects of exposure since gene expression compensated for learning disabilities (escape latency, walking distance and time spent not moving in the maze). Additionally, random forest analysis indicated that Kcnh3, Gnal, and Crlf1 were the most important genes for escape latency, while Hip1, Gnal and the low exposure level were the most important explanatory factors for passive behaviour (not moving). Altogether, this study showed transfer of POPs to the offspring brains after maternal exposure, modulating the expression level of genes involved in brain function.

Ingested plastics in northern fulmars (Fulmarus glacialis): A pathway for polybrominated diphenyl ether (PBDE) exposure?

Although it has been suggested that plastic may act as a vector for pollutants into the tissue of seabirds, the bioaccumulation of harmful contaminants, such as polybrominated diphenyl ethers (PBDEs), released from ingested plastics is poorly understood. Plastic ingestion by the procellariiform species northern fulmar (Fulmarus glacialis) is well documented. In this study, we measured PBDEs levels in liver tissue of northern fulmars without and with (0.13-0.43 g per individual) stomach plastics. PBDE concentrations in the plastic sampled from the same birds were also quantified. Birds were either found dead on beaches in southern Norway or incidentally caught in longline fisheries in northern Norway. PBDEs were detected in all birds but high concentrations were only found in liver samples from beached birds, peaking at 2900 ng/g lipid weight. We found that body condition was a significant factor explaining the elevated concentration levels in livers of beached birds. BDE209 was found in ingested plastic particles and liver tissue of birds with ingested plastics but was absent in the livers of birds without ingested plastics. This strongly suggests a plastic-derived transfer and accumulation of BDE209 to the tissue of fulmars, levels of which might prove useful as a general indicator of plastic ingestion in seabirds.

High Levels of Legacy and Emerging Contaminants in Killer Whales (Orcinus orca) from Norway, 2015 to 2017

Little is known of the movement or presence of unregulated, emerging contaminants in top predators. The aim of the present study was to conduct the first screening of legacy and emerging contaminants in multiple tissues of killer whales (Orcinus orca) from Norway and investigate tissue partitioning and maternal transfer. Blubber was collected from 8 killer whales in 2015 to 2017, in addition to muscle from 5 of the individuals, and kidney, liver, heart, and spleen from a neonate. We screened for 4 unregulated brominated flame retardants and found pentabromotoluene (PBT) and hexabromobenzene (HBB) at low levels in the blubber of all individuals (median PBT 0.091 ng/g lipid wt, median HBB 1.4 ng/g lipid wt). Levels of PBT and HBB (wet wt) were twice as high in the blubber than the muscle for each individual, confirming preferential accumulation in lipid-rich tissues. Perfluoroalkyl substances and total mercury levels were lower in the neonate than adults, suggesting less efficient maternal transfer of these substances. Polychlorinated biphenyl levels in blubber exceeded the threshold for onset of physiological effects (9 µg/g lipid wt) in 7 of the 8 whales, including the neonate. The presence of PBT and HBB in the neonate is the first evidence of maternal transfer of these unregulated contaminants in marine mammals. Our results are relevant for the continued environmental monitoring of contaminants in the Arctic. Environ Toxicol Chem 2021;40:1850-1860. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

First assessment of persistent organic pollutants in the Greater rhea (Rhea americana), a near-threatened flightless herbivorous bird of the Pampas grasslands

Persistent organic pollutants (POPs) are still globally distributed and can exert different effects on ecosystems. Little is known about the occurrence of these contaminants in terrestrial birds from South America. In this study, POPs were assessed for the first time in a flightless herbivorous species from the Pampas grasslands, the Greater rhea (Rhea americana). Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) were determined in 18 samples of feathers from free-ranging and captive individuals inhabiting four sites with different land uses in central Argentina. Among the 16 POPs tested in those feathers, 6 PCBs (28, 52, 101, 138, 153, and 180) and 8 OCPs (α-HCH, β-HCH, γ-HCH, p,p'-DDE, p,p'-DDD, o,p'-DDT, p,p'-DDT, and HCB) were quantified. No PBDEs were detected. The total concentration of POPs was higher in populations living in an intensive crop production area (agriculture 159 ng g ^-1 and farm: 97.53 ng g^-1) compared with the population in an urban area (zoo 45.86 ng g^-1) and an agroecosystem with extensive rearing of livestock (cattle rearing 36.77 ng g^-1). PCBs were the most abundant pollutants in all the populations studied. Lower chlorinated CB 52 and CB 101 were the principal PCB congeners detected, representing at least 70% of the total quantified. All populations studied showed a DDE + DDD/DDT ratio > 1, indicating a historical application of this insecticide. This study provides a new contribution to the scarce data on POP concentrations in South American bird species. Further investigations are needed to evaluate their potential effects on the health of individuals and populations.

Time Trend of Persistent Organic Pollutants and Metals in Greenlandic Inuit during 1994-2015

Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), organchlorine pesticides and perfluoroalkylated substances (PFASs) and heavy metals bioaccumulate in the marine food chain in the Arctic regions, and thus, the Greenlandic population has a higher body burden due to relatively high intake of marine mammals. We assessed the temporal trend for POPs, including PCB 153; 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE); oxychlordane; six PFASs; mercury; lead and selenium in Inuit from Ilulissat, Nuuk, and across Greenland (including thirteen towns/districts), from 1994 to 2015. Data showed a significant annual decrease of 6.85-8.61% for PCB153, 6.67-8.61% for p,p'-DDE, 6.11-9.52% for oxychlordane, 5.92-6.76% for mercury and 6.48-9.43% for lead in Inuit women from Nuuk, Ilulissat, and across thirteen Greenlandic districts. The blood selenium level of all Greenlandic women increased 1.01% annually, while the trend direction was negative for Nuuk women. A similar pattern was seen for men across Greenland, with a yearly decrease of 11.3% for PCB 153, 8.61% for p,p'-DDE, 15.6% for oxychlordane, 13.1% for mercury and 12.2% for lead. Perfluorooctane sulfonate, perfluorohexane sulfonate and perfluorooctanoic acid significantly decreased 5.82-11.7% annually for both women and men across Greenland. For perfluorononanoic acid, perfluorodecanoic acid and perfluoroundecanoic acid, we observed an increasing trend for women across Greenland. In conclusion, there was a decreasing trend of the regulated POPs and metals but a potential increasing trend of the nonregulated PFASs in the Greenlandic population between 1994 and 2015. The continuing biomonitoring of contaminants of concern is important to protect the Arctic population heath.

Correlations between Per- and Polyfluoroalkyl Substances and Body Morphometrics in Fledgling Shearwaters Impacted by Plastic Consumption from a Remote Pacific Island

We investigated the concentrations of 45 per- and polyfluoroalkyl substances (PFASs) in fledgling flesh-footed shearwater (Ardenna carneipes; n = 33) and wedge-tailed shearwater (A. pacifica; n = 9) livers via liquid chromatography-tandem mass spectrometry and their relationship to body morphometrics and ingested plastic mass recorded in 2019 on Lord Howe Island (NSW, Australia). Sixteen PFASs were detected, of which perfluorooctanesulfonate (PFOS) was the dominant compound, detected in 100% of birds (1.34-13.4 ng/g wet wt). Long-chain perfluorocarboxylic acids, including perfluorodecanoic acid (PFDA; <0.04-0.79 ng/g wet wt) and perfluorotridecanoic acid (PFTrDA; <0.05-1.6 ng/g wet wt) were detected in >50% of birds. There was a positive correlation between PFDA and PFTrDA concentrations and wing chord length (R_s  = 0.36, p = 0.0204; R_s  = 0.44, p = 0.0037, respectively), and between PFDA concentrations and total body mass (R_s  = 0.33, p = 0.032), suggesting that these compounds may impact shearwater fledgling morphometrics. Plastic was present in the intestinal tract of 79% of individuals (<7.6 g), although there was no correlation between PFAS concentrations and plastic mass, indicating that ingested plastic is not the likely primary exposure source. The widespread occurrence of PFASs in fledgling marine birds from a relatively pristine location in the Southern Hemisphere suggests that further studies in adult shearwaters and other marine birds are warranted to investigate whether there are any long-term physiological effects on bird species. Environ Toxicol Chem 2021;40:799-810. © 2020 SETAC.

Per- and Polyfluoroalkyl Substances Are Positively Associated with Thyroid Hormones in an Arctic Seabird

Per- and polyfluoroalkyl substances (PFAS) are associated with several disrupted physiological and endocrine parameters. Regarding endocrine mechanisms, laboratory studies suggest that PFAS could disrupt the thyroid hormone system and alter circulating thyroid hormone concentrations. Thyroid hormones play a ubiquitous role-controlling thermoregulation, metabolism, and reproduction. However, evidence for disruption of thyroid hormones by PFAS remains scarce in wildlife. The present study investigated the associations between concentrations of PFAS, thyroid hormones, and body condition in an arctic seabird, the black-legged kittiwake (Rissa tridactyla). We collected blood from kittiwakes sampled in Svalbard, Norway (2013 and 2014). Plasma samples were analyzed for total thyroxine (TT4) and total triiodothyronine (TT3) concentrations; detected PFAS included branched and linear (lin) C₈ perfluoroalkyl sulfonates (i.e., perfluoroctane sulfonate [PFOS]) and C₉ -C₁₄ perfluoroalkyl carboxylates (PFCAs). The dominant PFAS in the kittiwakes were linPFOS and C₁₁ - and C₁₃ -PFCAs. Generally, male kittiwakes had higher concentrations of PFAS than females. We observed positive correlations between linPFOS, C₁₀ -PFCA, and TT4 in males, whereas in females C_12-14 -PFCAs were positively correlated to TT3. Interestingly, we observed contrasted correlations between PFAS and body condition; the direction of the relationship was sex-dependent. Although these results show relationships between PFAS and circulating thyroid hormone concentrations in kittiwakes, the study design does not allow for concluding on causal relationships related to effects of PFAS on the thyroid hormone system. Future experimental research is required to quantify this impact of PFAS on the biology of kittiwakes. The apparently different associations among PFAS and body condition for males and females are puzzling, and more research is required. Environ Toxicol Chem 2021;40:820-831. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

A Polar outlook: Potential interactions of micro- and nano-plastic with other anthropogenic stressors

Polar marine ecosystems may have higher sensitivity than other ecosystems to plastic pollution due to recurrent physical and biological features; presence of ice and high UV radiation, slow growth rates and weak genetic differentiation of resident biota, accumulation of persistent organic pollutants and heavy metals, and fast rates of warming and global ocean acidification. Here, we discuss potential sources of and exposure to micro- and nano-plastic in polar marine ecosystems and potential mixture effects of micro- and nano-plastic coupled with chemical and climate related stressors. We address the anthropogenic contaminants likely to be 'high risk' for interactions in Arctic and Antarctic waters for reasons such as accumulation under sea-ice, a known sink for plastic particulates. Consequently, we address the potential for localised plastic-chemical interactions and possible seasonal fluctuations in interactions associated with freeze-thaw events. The risks for keystone polar species are also considered, incorporating the behavioural and physiological traits of biota and addressing potential 'hotspot' areas. Finally, we discuss a possible direction for future research.

Simulating changes in polar bear subpopulation growth rate due to legacy persistent organic pollutants - Temporal and spatial trends

Although atmospheric concentrations of many conventional persistent organic pollutants (POPs) have decreased in the Arctic over the past few decades, levels of most POPs and mercury remain high since the 1990s or start to increase again in Arctic areas, especially polar bears. So far, studies generally focused on individual effects of POPs, and do not directly link POP concentrations in prey species to population-specific parameters. In this study we therefore aimed to estimate the effect of legacy POPs and mercury on population growth rate of nineteen polar bear subpopulations. We modelled population development in three scenarios, based on species sensitivity distributions (SSDs) derived for POPs based on ecotoxicity data for endothermic species. In the first scenario, ecotoxicity data for polar bears were based on the HC₅₀ (the concentration at which 50% of the species is affected). The other two scenarios were based on the HC₅ and HC₉₅. Considerable variation in effects of POPs could be observed among the scenarios. In our intermediate scenario, we predicted subpopulation decline for ten out of 15 polar bear subpopulations. The estimated population growth rate was least reduced in Gulf of Boothia and Foxe Basin. On average, PCB concentrations in prey (in μg/g toxic equivalency (TEQ)) posed the largest threat to polar bear subpopulations, with negative modelled population growth rates for the majority of subpopulations. We did not find a correlation between modelled population changes and monitored population trends for the majority of chemical-subpopulation combinations. Modelled population growth rates increased over time, implying a decreasing effect of PCBs, DDTs, and mercury. Polar bear subpopulations are reportedly still declining in four out of the seven subpopulations for which sufficient long-term monitoring data is available, as reported by the IUCN-PBSG. This implies that other emerging pollutants or other anthropogenic stressors may affect polar bear subpopulations.

Organochlorine pesticide bioaccumulation in wild Nile crocodile (Crocodylus niloticus) fat tissues: Environmental influences on changing residue levels and contaminant profiles

Biologically significant concentrations of organochlorine pesticides (OCPs) continue to be reported in wildlife populations and are of particular concern in species that occupy the highest trophic levels. Nile crocodiles (Crocodylus niloticus) are important apex predators occurring throughout much of tropical and subtropical sub-Saharan Africa, where they inhabit estuarine and freshwater habitats often impacted by contamination. In this study we examined pesticide residue accumulation in fat tissue from Nile crocodiles at Lake St Lucia, South Africa, where historically large quantities of OCPs have been used for agriculture and disease control. During 2019, we collected tail fat samples from wild (n = 21) and captive (n = 3) individuals to examine the influence of habitat, body size and sex on variations in bioaccumulation. The principal contaminant found was p,p'-DDE, a major persistent metabolite of DDT, which continues to be used in the region for combating malaria. Tissue p,p'-DDE concentrations in wild crocodiles (95-1200 ng g^-1 ww) were significantly (p < 0.05) higher compared to captive individuals (23-68 ng g^-1 ww) and strongly correlated (R² > 0.70) to body length. Male (n = 14) and female (n = 7) wild crocodiles exhibited similar contaminant body burdens, however, total concentrations were substantially lower than those measured in the same population during 2016/2017. Marked differences in residue levels and profiles appear to reflect changes in food availability and dietary exposure associated with a shift in environmental conditions. These findings suggest that periods of environmental stress may be associated with enhanced toxicological risk in crocodiles. Additional work is needed to better understand contaminant accumulation and elimination mechanisms in crocodiles, and their potential effects on reproductive health.

Suspect screening based on market data of polar halogenated micropollutants in river water affected by wastewater

Wastewater treatment plants (WWTPs) are known point sources of contaminants of emerging concern (CECs) to the aquatic environment, but current knowledge is mostly limited to well-known chemical structures. In this study, we sought to identify unknown CECs polluting the aquatic environment through a novel suspect screening approach for organohalogens, i.e. organic halogenated molecules often toxic and resistant to transformation and characterised as persistent organic pollutants (POPs). Surface water samples were collected with passive samplers in the Fyris River catchment (Uppsala, Sweden), analysed using liquid chromatography high-resolution mass spectrometry (LC-HRMS) and screened for organohalogens using a suspect screening approach based on market data obtained from a regulatory authority. Thirteen suspects from very different application areas were confirmed or tentatively identified with high confidence, including seven previously unknown structures (diflufenican, chlorzoxazone, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 2,4-disulfamyl-5-trifluoromethylaniline, 5-amino-2-chlorotoluene-4-sulfonic acid, perfluoropentane-1-sufonic acid, (2-chlorophenyl)(hydroxy)methanesulfonic acid). Spatiotemporal occurrence patterns were detected, which helped to understand the usage pattern of the chemicals and pinpoint potential pollution sources, e.g. specific WWTPs in the catchment. Several of the newly identified structures had virtually no information publicly available and were detected years after their last registered use, which highlights the knowledge gaps and concerns about POPs.

Heart rate variation and human body burdens of environmental mixtures in the Cree First Nation communities of Eeyou Istchee, Canada

INTRODUCTION

Heart rate variability (HRV) is a measure of cardiac autonomic regulation that examines the variation in beat-to-beat fluctuations in heart rate. While many exposure-based studies have examined the effects of single or similar groups of contaminants on HRV parameters, none have examined the association between complex environmental mixtures, including organic and elemental contaminants, and HRV.

METHODS

Using data collected from the Multi-Community Environment-and-Health Study in Eeyou Istchee (Quebec, Canada), we assessed HRV in two time domain measures: root mean square of successive differences (RMSSD) and standard deviation of the N-N (RR) intervals (SDNN); and in three frequency domains: high frequency (HF), low-frequency (LF), and very-low frequency (VLF) in 443 participants. We first examined mixture effects of nineteen organic and metal contaminants in blood using principal component analysis (PCA) and a multivariable general linear regression on HRV responses, adjusting for age, sex, body mass index, smoking status, and kidney disease covariates. We subsequently assessed HRV outcome response variables using Bayesian kernel machine regression (BKMR) to further examine individual contaminant contribution and overall mixture effects.

RESULTS

In the PCA, a significant positive association was observed between RMSSD and principal component (PC) axis 2, which was highly positively-loaded for nickel and moderately negatively-loaded for mercury. A negative association between SDNN and PC-1, which was highly positively-loaded for all PCBs (polychlorinated biphenyls) and organochlorines and moderately positively-loaded for mercury, was observed. Additionally, a significant and positive association was observed between PC-2 and SDNN and a significant and negative association between PC-3 (negatively loaded for cadmium) and LF. Associations with contaminants were not observed for HF or VLF. BKMR results suggest that trans-nonachlor and cis-nonachlor are primarily responsible for reductions in HRV; however, their contributions to HRV deficits was non-significant when examined as a complete mixture.

CONCLUSIONS

While PCA results suggested that organochlorines, mercury, nickel, and cadmium may all play a role in altering various HRV, subsequent BKMR analysis illustrated the individual components driving these effects may be trans- and cis-nonachlor and nickel and likely not mercury or cadmium. However, other contaminants appear to temper this effect when the entire mixture of chemicals is assessed as a whole. This study expands our knowledge of the effects of environmental contaminant mixtures on HRV, which is especially important in exposed populations such as those in the Eeyou Istchee territory, whilst utilizing novel statistical methods such as PCA and BKMR to examine co-exposures concurrently.

BDE-209 and DBDPE induce male reproductive toxicity through telomere-related cell senescence and apoptosis in SD rat

Decabrominated diphenyl ether (BDE-209) and decabromodiphenyl ethane (DBDPE) are common flame retardants utilized in many kinds of electronic and textile products. Due to their persistence and bioaccumulation, BDE-209 and DBDPE extensively exist in the surrounding environment and wild animals. Previous studies have indicated that BDE-209 could induce male reproductive toxicity, whereas those of DBDPE remains relatively rare. In this study, we investigated the effects of both BDE-209 and DBDPE on reproductive system in male SD rats, and explored the potential mechanisms under the reproductive toxicity of BDE-209 and DBDPE. Male rats were orally administered with BDE-209 and DBDPE (0, 5, 50 and 500 mg/kg/day) for a 28-day exposure experiment. The current results showed that BDE-209 and DBDPE led to testicular damage in physiological structure, decreased the sperm number and motility, and increased the sperm malformation rates in rat. Moreover, BDE-209 and DBDPE could damage the telomeric function by shortening telomere length and reducing telomerase activity, which consequently caused cell senescence and apoptosis in testis of rat. This could contribute to the decline of sperm quality and quantity. In conclusion, BDE-209 and DBDPE led to reproductive toxicity by inducing telomere dysfunction and the related cell senescence and apoptosis in testis of SD rat. Comparatively, BDE-209 had more severe effects on male reproduction. Our findings may provide new insight into the potential deleterious effects of BFRs on male reproductive health.

Liver histopathology of Baltic grey seals (Halichoerus grypus) over three decades

The liver plays an important role in the metabolism and elimination of endogenic and exogenic lipid-soluble compounds. Multiple studies have shown that polychlorinated biphenyls (PCB) and dichlorodiphenyl trichloroethane (DDT) lead to morphological changes in liver cells. The aim of the present study was therefore to analyse liver changes over time in Baltic grey seals (Halichoerus grypus) and to correlate these with historical PCB and DDT contaminations. A total of 191 liver samples were collected between 1981 and 2015 in the Gulf of Bothnia and northern Baltic Proper. Six histological features were evaluated, including portal mononuclear cell infiltration, random mononuclear cell infiltration, lipid granulomas, hepatocellular fat vacuoles, hepatic stellate cells and mild multifocal bile duct hyperplasia accompanied by portal fibrosis. Three of the six lesions showed a significant correlation with age. Furthermore, a positive correlation between portal mononuclear cell infiltration and mild multifocal bile duct hyperplasia was found. Additionally, lipid granulomas were significantly correlated with hepatic stellate cells. More importantly, hepatic stellate cells and mild multifocal bile duct hyperplasia were correlated with adipose tissue (blubber) concentrations of ƩPCB, measured in a subsample (n = 34) of all individuals. No correlation with lesions and ƩDDT concentrations were found. These results show that age is an important factor for the development of these liver lesions, but PCBs burden may be an influencing factor. This is in agreement with previous studies of marine mammals in the Baltic Sea as well as in the Arctic. We therefore conclude that not only age of the animals, but also exposure to PCBs should be taken into account when understanding and evaluating the current health status of Baltic grey seals.

Two Decades' Variation of Trace Elements in Bones of the Endangered East Asian Finless Porpoise (Neophocaena asaeorientalis sunameri) from the East China Sea, China

There has been increasing concern about trace element accumulation in finless porpoises over the past decades, while the long-term variation of its concentration has been little known. Since most soft tissues of porpoises in the past were not preserved until now, the bone tissue is the only ideal material available. Here, 27 East Asian finless porpoise bone samples collected from Nantong, the East China Sea during two periods (1984-1992 and 2009) were used to explore the temporal variation of nine typical elements' concentration (Fe, Mn, Cu, Ni, Hg, Cr, Pb, As, and Cd, dry weight). An upward trend for total trace element accumulation from 329.04 mg/kg in 1984-1992 to 1535.81 mg/kg in 2009 was found; this could have resulted from the increasing industrial development in the Nantong region. The Mn, Fe, and As levels increased significantly while the concentrations of Cd, Cu, and Pb significantly decreased. Generally, our results suggested that most trace elements posed low threats to East Asian finless porpoises' health during both periods, while elements Mn (2009), Ni (both periods), Fe (2009), and As (2009) posed a potentially higher health risk to porpoises. Thus, the trace element levels warrant concern and continuous monitoring.

Temporal transcriptome analysis in female scallop Chlamys farreri: First molecular insights into the disturbing mechanism on lipid metabolism of reproductive-stage dependence under benzo[a]pyrene exposure

Polycyclic aromatic hydrocarbons (PAHs) are one of the most widespread persistent organic pollutants (POPs) in marine environment. Benzo[a]pyrene (B[a]P), the most toxic carcinogen of PAHs, is widely studied as a representative that interferes with lipid metabolism. However, the underlying molecular mechanisms of lipid metabolism by B[a]P interference towards bivalve, one of the marine-pollution bio-indicators have not been elucidated yet, especially during gonadal development which is closely associated with lipids. In this study, female scallops Chlamys farreri were cultured with natural and 4 μg/L B[a]P exposed seawater, respectively, and a multi-stage (proliferative, growth, mature, and spawn stage) ovarian transcriptome profiling was performed to decipher the reproductive stage-dependence disturbing mechanisms on lipid metabolism caused by B[a]P in bivalves. The results revealed the potential molecular mechanism of B[a]P-induced triglycerides (TGs) accumulation, which probably resulted from the collaboration of promoting synthesis and inhibiting metabolization of TGs, notably, this mechanism also occurred at spawn stage. Correspondingly, B[a]P and TGs contents measured in ovary offered direct biochemical evidences for the interference effects and stage-dependent accumulation patterns of B[a]P. Moreover, the gene expressions of fatty acids synthesis related enzymes were down-regulated cooperatively, illustrating the molecular compensatory mechanism that reduced susceptibility from oxidative damage. And these results further emphasized the important role of prostaglandins (PGs) in immune response mediated by arachidonic acid metabolism. In addition, this study explored the underlying molecular mechanism affected by B[a]P on sterol metabolism, which possibly posed a threat to normal reproductive functions in bivalves. Taken together, our findings filled the gap of the stage-dependent interference molecular mechanisms on lipid metabolism behind bivalves, and provided a new perspective for investigating the adaptive mechanisms of bivalves under POPs stress.

Environmental effects of offshore produced water discharges: A review focused on the Norwegian continental shelf

Produced water (PW), a large byproduct of offshore oil and gas extraction, is reinjected to formations or discharged to the sea after treatment. The discharges contain dispersed crude oil, polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), metals, and many other constituents of environmental relevance. Risk-based regulation, greener offshore chemicals and improved cleaning systems have reduced environmental risks of PW discharges, but PW is still the largest operational source of oil pollution to the sea from the offshore petroleum industry. Monitoring surveys find detectable exposures in caged mussel and fish several km downstream from PW outfalls, but biomarkers indicate only mild acute effects in these sentinels. On the other hand, increased concentrations of DNA adducts are found repeatedly in benthic fish populations, especially in haddock. It is uncertain whether increased adducts could be a long-term effect of sediment contamination due to ongoing PW discharges, or earlier discharges of oil-containing drilling waste. Another concern is uncertainty regarding the possible effect of PW discharges in the sub-Arctic Southern Barents Sea. So far, research suggests that sub-arctic species are largely comparable to temperate species in their sensitivity to PW exposure. Larval deformities and cardiac toxicity in fish early life stages are among the biomarkers and adverse outcome pathways that currently receive much attention in PW effect research. Herein, we summarize the accumulated ecotoxicological knowledge of offshore PW discharges and highlight some key remaining knowledge needs.

Organochlorine pesticides and polychlorinated biphenyls in common kestrel eggs from the Canary Islands: Spatiotemporal variations and effects on eggshell and reproduction

Organochlorine (OC) pesticides were widely used on the Canary Islands (Spain) for intensive crop production and against plagues of African locust. A previous study performed in 1988-1994 showed a high concentration of p,p'-DDE in the eggs of common kestrels (Falco tinnunculus) from the island of Tenerife. The present study shows OC pesticide and polychlorinated biphenyl (PCBs) levels in 40 unhatched common kestrel eggs collected from southern Tenerife between 2009 and 2016. The protoporphyrin IX in eggshells has also been analysed in order to explore the use of this pigment as a biomarker. Egg biometry, status of embryo development, eggshell thickness and mass of extractable lipids of each egg were recorded. Surrounding land use and reproductive parameters (hatching and fledging rates) were obtained for each nest. The most abundant compound was p,p'-DDE (15.0 μg/g d.w), followed by PCBs (0.46 μg/g d.w.). The decline in p,p'-DDE levels in southern Tenerife (with 23.6 μg/g d.w. in 1988-1994) was 36.4%. p,p'-DDE levels were positively associated with the surface of active and abandoned cropland in a 200 m-radius around the nest and with proximity to urban areas. PCB levels were associated with proximity to roads. Shell thickness was negatively affected by the p,p'-DDE concentration. The concentration of protoporphyrin IX in the eggshell was negatively associated with the concentration of hexachlorobenzene in the egg content. Despite the total ban on the use of p,p'-DDT in Spain since 1986, p,p'-DDE levels remain elevated in those areas in which that use was formerly intensive.

Life cycle bioenergetics of the gray seal (Halichoerus grypus) in the Baltic Sea: Population response to environmental stress

Wildlife population dynamics are shaped by multiple natural and anthropogenic factors, including predation, competition, stressful life history events, and external environmental stressors such as diseases and pollution. Marine mammals such as gray seals rely on extensive blubber layers for insulation and energy storage, making this tissue critical for survival and reproduction. This lipid rich blubber layer also accumulates hazardous fat soluble pollutants, such as polychlorinated biphenyls (PCBs), that can directly impact adipose function or be mobilized during periods of negative energy balance or transferred to offspring to exert further impacts on target tissues or vulnerable life stages. To predict how marine mammals will respond to ecological and anthropogenic stressors, it is necessary to use process-based modelling approaches that integrate environmental inputs, full species life history, and stressor impacts with individual dynamics of energy intake, storage, and utilization. The purpose of this study was to develop a full lifecycle dynamic energy budget and individual based model (DEB-IBM) that captured Baltic gray seal physiology and life history, and showcase potential applications of the model to predict population responses to select stressors known to threaten gray seals and other marine mammals around the world. We explore variations of three ecologically important stressors using phenomenological simulations: food limitation, endocrine disrupting chemicals that reduce fertility, and infectious disease. Using our calibrated DEB-IBM for Baltic gray seals, we found that continuous incremental food limitation can be more detrimental to population size than short random events of starvation, and further, that the effect of endocrine disruptors on population growth and structure is delayed due to bioaccumulation, and that communicable diseases significantly decrease population growth even when spillover events are relatively less frequent. One important finding is the delayed effect on population growth rate from some stressors, several years after the exposure period, resulting from a decline in somatic growth, increased age at maturation and decreased fecundity. Such delayed responses are ignored in current models of population viability and can be important in the correct assessment of population extinction risks. The model presented here provides a test bed on which effects of new hazardous substances and different scenarios of future environmental change affecting food availability and/or seal energetic demands can be investigated. Thus, the framework provides a tool for better understanding how diverse environmental stressors affect marine mammal populations and can be used to guide scientifically based management.

Non-targeted screening workflows for gas chromatography-high-resolution mass spectrometry analysis and identification of biomagnifying contaminants in biota samples

The health of key species in the Baltic region has been impaired by exposure to anthropogenic hazardous substances (AHSs), which accumulate in organisms and are transferred through food chains. There is, thus, a need for comprehensive characterization of the occurrence and accumulation of AHSs in the ecosystem. In this study, we use a non-target screening (NTS) approach for this purpose. A major challenge in NTS of biological samples is the removal of matrix components such as lipids that may interfere with the detection and identification of compounds of interest. Here, we combine gel permeation chromatography with Florisil^® column fractionation to achieve sufficient lipid removal for gas chromatography–high-resolution mass spectrometry analysis using electron ionization (EI) and electron capture negative ion chemical ionization (ECNI). In addition, we present new data processing workflows designed to systematically find and identify frequently occurring and biomagnifying AHSs, including known, emerging, and new contaminants. Using these workflows, we discovered a wide range of contaminants in tissue samples from blue mussels, fish, and marine mammals, and calculated their biomagnification factors (BMFs). Compounds with BMFs above 1 for herring and at least one marine mammal included legacy chlorinated pollutants (polychlorinated biphenyls, DDTs, chloro-benzenes/cyclohexanes, chlordanes, toxaphenes, dieldrin), polybrominated diphenyl ethers (PBDEs), and brominated biphenyls. However, there were also several halogenated natural products (halogenated methoxylated brominated diphenyl ethers, 1′-methyl-1,2′-bipyrroles, 1,1′-dimethyl-2,2′-bipyrroles, and the halogenated monoterpene mixed halogenated compound 1) as well as the novel flame retardant Dechlorane 602 and several polycyclic aromatic hydrocarbons, terpenoids, and steroids. The legacy pollutants exhibited the expected biomagnification behavior, demonstrating the utility of the unguided data processing workflow.

Distribution and ECo-Toxicological Risk Assessment of Legacy Persistent Organic Pollutants in Surface Water of Talar, Babolrood and Haraz Rivers

In the outer Alborz Range in the Northern Province of Iran, the Haraz, Talar and Babolrood Rivers are the three largest rivers where most of the agricultural, aquacultural and industrial activities are found. Total indicator polychlorinated biphenyls (iPCBs) ranged ND–474, ND–273 and ND–559 ng/L in Haraz, Talar and Babolrood Rivers, respectively. Significantly lower (p < 0.05) concentrations of DDT, lindane and dieldrin were observed in the upstream stations than downstream stations of both Babolrood and Haraz Rivers. However, in Talar River, PCB residues in upstream was significantly higher (p < 0.05) than downstream. Furthermore, PCB-28 in Talar River and PCB-101 and PCB-153 in Bablrood and Haraz Rivers were high in water samples at all stations. A significant difference was observed among the stations. In October, November and December, there was negligible variations in total PCB concentration among the stations. Alarming levels of some of the legacy persistent organic pollutants (POPs) may pose adverse effects on the aquatic species dwelling in the Talar, Babolrood and Haraz Rivers of Iran.

Early Breeding Failure in Birds Due to Environmental Toxins: A Potentially Powerful but Hidden Effect of Contamination

Toxin emissions and legacies are major global issues affecting many species through, among other effects, endocrine disruption and reproductive impairment. Assessment of toxin risk to wildlife focuses mostly on offspring-related metrics, while the lack of breeding initiation or early breeding failure has received less attention. We tested whether exposure to methyl mercury (MeHg) results in early breeding failure and reduced number of breeding birds using observational and experimental data. We used 21 years of numbers of breeding pairs of colonially breeding wild Great Egrets (Ardea alba) in response to annual and geographical variation upon exposure to environmental MeHg. After controlling for food availability, we found a strong negative association between MeHg exposure and the number of breeding Great Egrets. We report reductions of >50% in breeding numbers under exposure levels otherwise associated with <20% reduction in post-egg-laying breeding success. Experimental exposure of White Ibises (Eudocimus albus) to MeHg also caused early breeding failure and a ∼20% reduction in breeding numbers at environmentally relevant exposures. The demographic consequences of reductions in breeding pairs are additive to known and typically studied impairments in postlaying reproductive success. Net demographic effects of exposure to endocrine disruptors may often be strongly underestimated if early breeding failure is not measured.

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.

Aluminum hydroxide colloid facilitated transport of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in porous media

In this study, aluminum hydroxide colloids, which widely exist in soils, were selected to investigate their effect on the infiltration of an abundant congener of PBDEs (BDE-47) to groundwater. The batch and column experiments were conducted to study the co-migration of aluminum hydroxide colloid and BDE-47 in two sand media with particle sizes of 2-4.75 and 0.15 mm. The results indicated that the colloid significantly increased the transport of BDE-47 to 24.32% and 65.84% in the vadose zone of coarse and fine sand columns, respectively. The adsorption and blocking effect were found to be the two main functions during the co-migration of aluminum hydroxide colloids with BDE-47. Specifically, BDE-47 that adsorbed on colloids moved faster in the coarse porous media, and the breakthrough peak of BDE-47 appeared early in the media at an approximate pore volume of 0.15. In comparison, colloids that adsorbed onto the fine porous media formed a layer that blocked the adsorption of BDE-47 onto the fine porous media. This weakened the protection capacity of the vadose zone and led to a greater than 80% amount of BDE-47 breakthrough to the vadose zone.

Optimization of microbial assisted phytoremediation of soils contaminated with pesticides

580 microbial strains were isolated from the rhizosphere of the plants Cucurbita pepo L. and Xanthium strumarium grown on soil contaminated with dichlorodiphenyltrichloroethane (DDT) and its metabolites. During the cultivation, two bacterial strains were selected because of their ability to grow on media containing 0.5-5.0 mg L^-1 of dichlorodiphenyldichloroethylene (DDE) as the sole carbon source. They were identified as Bacillus vallismortis and Bacillus aryabhattai. Both of these species were shown to have a high capacity for the utilization of DDE - more than 90% of which was consumed after 21 days of cultivation. Laboratory experiments were carried out then to assess the possibility of using these strains for the decontamination of organochlorine pesticides (OCPs) contaminated soils. Inoculation of C. pepo and X. strumarium with our isolates B. vallismortis and B. aryabhattai resulted in a reduction of the pollutant stress to the plants as shown by an increase both in aboveground and in root biomass. The microorganisms enhanced the uptake and phytostabilization potential of C. pepo and X. strumarium and can be applied for the treatment of DDE contaminated soils.

Relevance of current PCB concentrations in edible fish species from the Mediterranean Sea

Legal restrictions and bans have led to a steady decrease in PCB environmental concentrations. Yet, in recent years PCBs have been found at very high levels in the Mediterranean Sea, for instance, in some apex predators. This work aimed to investigate current PCB (eighteen congeners: #28,52,77,81,101,105,114,118,123,126,138,153,156,157,167,169,180,189) concentrations in the Mediterranean Sea and their relevance today, focusing on their occurrence in edible fish species typically consumed in the Mediterranean diet. In spring 2017, a total of 48 fish samples from the Northern Thyrrenian Sea were collected: 16 specimens of sardine (Sardina pilchardus), 16 of anchovy (Engraulis encrasicolus) and 16 of bogue (Boops boops). PCBs were quantified in the muscle of the animals by means of GC-QqQ-MS. They were found in all samples at the greatest concentrations (ng/g w.w.) in sardine (4.15-17.9, range), and very similar values between anchovy (1.01-7.08) and bogue (1.46-7.22). WHO-TEQ PCB values followed the same order, i.e. sardine (0.410-1.24, range in pg/g w.w.) > anchovy (0.0778-0.396) ~ bogue (0.0726-0.268). These concentrations lied below the European limits of 75 ng/g (w.w.) for the six indicator PCBs and 6.5 pg/g WHO-TEQ for dioxins and dioxin-like PCBs in muscle meat of fish. Additionally, estimated weekly intakes (EWI, in pg WHO-TEQ/Kg/week) for sardine (1.2), anchovy (0.29) and bogue (0.35) scored below the safe value proposed by EFSA of 2 pg WHO-TEQ/Kg/week. When comparing with data reported for the same species in previous Mediterranean studies, values found here were lower than those surveyed in the late 90s and early 2000s; however, they were often not notably different from concentrations reported in last years. This builds up on the concept of a current slow decrease of PCBs in the Mediterranean Sea, likely linked to new inputs and/or remobilization of burdens, and reinforces the need of continous monitoring of these legacy contaminants still ubiquitous today.

A baseline for POPs contamination in Australian seabirds: little penguins vs. short-tailed shearwaters

While globally distributed throughout the world's ecosystems, there is little baseline information on persistent organic pollutants (POPs) in marine environments in Australia and, more broadly, the Southern Hemisphere. To fill this knowledge gap, we collected baseline information on POPs in migratory short-tailed shearwaters (Ardenna tenuirostris) from Fisher Island, Tasmania, and resident little penguins (Eudyptula minor) from Phillip Island, Victoria. Levels of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and brominated flame retardants (BFRs) were determined from blood samples, with total contamination ranging 7.6-47.7 ng/g ww for short-tailed shearwaters and 0.12-46.9 ng/g ww for little penguins. In both species contamination followed the same pattern where PCBs>OCPs>BFRs. BFR levels included the presence of the novel flame retardant hexabromobenzene (HBB). These novel results of POPs in seabirds in southeast Australia provide important information on the local (penguins) and global (shearwaters) distribution of POPs in the marine environment.

Variation in skull bone mineral density of ringed seals (Phoca hispida) from the Gulf of Bothnia and West Greenland between 1829 and 2019

Bone is remodelled constantly through a balance of bone formation and resorption. This process can be affected by various factors such as hormones, vitamins, nutrients and environmental factors, which can create an imbalance resulting in systemic or local bone alteration. The aim of the present study was to analyse the changes in bone mineral density (BMD) over time in skulls of ringed seals (Pusa hispida) from the Baltic and Greenland using museum samples. Overall, 303 skulls (102 Male, 89 Female, 112 unknown) were used for bone investigations and were divided into three periods according to collection year: before 1958 (n = 167), between 1958 and 1989 (n = 40) and after 1994 up to 2019 (n = 96). All skulls were examined by dual-energy X-ray absorptiometry to obtain the BMD. Skull BMD of the Baltic seals was positively correlated with the historical polychlorinated biphenyls (PCB) contamination having potential effects on the constitution of bones. BMD fluctuated between the three study periods (LM: p-value < 0.001, F-value = 47.5) with the lowest BMD found between 1897 and 1957, in the Gulf of Bothnia, where the highest peak of contaminant concentration was in the second period. BMD levels increased with increasing PCB concentration (LM: p < 0.001). The Greenland population showed significant lower BMD levels in the pollution and post-pollution period than the Baltic population (LM: p < 0.001). It also revealed a higher BMD in males than in females (LM: p = 0.03). In conclusion, the variations between 1829 and 2019 in the Baltic Sea and Greenland may to a certain extent reflect normal fluctuations; however, this study revealed several factors affecting BMD, including sex and PCB levels.