Perfluoroalkyl substances in polar bear mother-cub pairs: a comparative study based on plasma levels from 1998 and 2008

Comparative review of One Health and Indigenous approaches to wildlife research in Inuit Nunangat

There is increasing interest in One Health and Indigenous methodologies and approaches in wildlife research, but they are not widely used research applications in the Arctic. Both approaches are wide in scope and originate from different knowledge systems but are often compared synonymously. We review the literature of overlap between the term One Health and Inuit Qaujimajatuqangit (Inuit Indigenous Knowledge) throughout Inuit Nunaat on wildlife research. Three databases (SCOPUS, Web of Science, and BIOSIS) were used to find English language articles and books within the bounds of Inuit Nunaat. While One Health and Inuit Qaujimajatuqangit research approaches share synergies, they are fundamentally disparate owing to their differences in epistemology, including views on the natural environment and wildlife management. We describe current examples of One Health being operationalized in Inuit Nunaat and identify potential to address larger and more complex questions about wildlife health, with examples from terrestrial and marine Arctic wildlife. Both Indigenous methodologies and One Health naturally have a human component at their core, which seamlessly lends itself to discussions on wildlife management, as human actions and regulations directly impact environment and wildlife health.

Fluoro-functionalized plant biomass adsorbent: Preparation and application in extraction of trace perfluorinated compounds from environmental water samples

Perfluorinated compounds (PFCs) are toxic and widely present in the environment, and therefore effective adsorbents are required to remove PFCs from environmental water. In the present study, a new type of fluorinated biomass materials was synthesized via an ingenious fluorosilanization reaction. These adsorbents were applied for the adsorption of 13 typical PFCs, including perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs). By comparing their adsorption performance, Fluorinated cedar slag (FCS) was discovered to have the best absorption efficiency and enabled highly efficient enrichment of PFCs. The adsorption recovery of FCS with the investigated PFCs is greater than 90% under the optimal adsorption condition. Ascribed to the high affinity of F-F sorbent-sorbate interaction, FCS had good adsorption capacities of PFCs from aqueous solution, with the maximum adsorption capacity of 15.80 mg/g for PFOS and 10.71 mg/g for PFOA, respectively. Moreover, the adsorption time could be achieved in a short time (8 min). Using the FCS absorbent, an innovative FCS-solid phase extraction assisted with high performance liquid chromatography-electrospray-tandem mass spectrometry (FCS-SPE-HPLC-ESI-MS/MS) method was first developed to sensitively detect PFCs in the environmental water samples. The intra-day and inter-day recovery rates of the 13 compounds ranged from 90.7%-104.3%, with the RSD of 2.1%-4.7% (intra-day) and 2.5%-8.5% (inter-day), respectively. This research demonstrates the potential of the newly fluoro-functionalized plant biomass to adsorb PFCs from environmental water, with the advantages of high adsorption efficiencies, high anti-interference, easy operation and low economic cost.

Bioaccumulation, tissue distributions, and maternal transfer of perfluoroalkyl carboxylates (PFCAs) in laying hens

Laying hens were exposed to feeds spiked with a series of perfluoroalkyl carboxylates (PFCAs) ranging from perfluorobutanoic acid (C4) to perfluorooctadecanoic acid (C18) to investigate their bioaccumulation, tissue distribution, and maternal transfer. We found that PFCAs with longer carbon chains (>8) were more efficiently absorbed in the gastrointestinal tract than those with shorter chains (≤8), and that the rate of depuration varied inversely with the carbon chain length in a U-shaped pattern. Moreover, bioaccumulation potential increased with increasing carbon-chain length, except for C4. Distinct affinities were observed for specific carbon-chain PFCAs across various tissues, evident from their differential accumulation during both uptake and depuration phases. Specifically, C9 showed a higher affinity for serum and liver, C12 was more prevalent in yolk, C14 was notably abundant in the brain, and C18 was predominant in other tissues. Furthermore, the egg-maternal ratio (EMR) increased with increasing carbon-chain length from C7 to C11 and reached a plateau phase for C12 to C18. Our study also confirmed the key role of phospholipids in the tissue distribution and maternal transfer of long-chain PFCAs. This study sheds light on the interaction between PFCAs and biological tissues and reveals the toxicokinetic factors that influence the bioaccumulation of PFCAs. Further research is needed to identify the specific proteins or components that mediate the tissue-specific affinity for different carbon-chain lengths of PFCAs.

Phytoremediation prospects of per- and polyfluoroalkyl substances: A review

Extensive use of per- and polyfluoroalkyl substances (PFASs) in various industrial activities and daily-life products has made them ubiquitous contaminants in soil and water. PFAS-contaminated soil acts as a long-term source of pollution to the adjacent surface water bodies, groundwater, soil microorganisms, and soil invertebrates. While several remediation strategies exist to eliminate PFASs from the soil, strong ionic interactions between charged groups on PFAS with soil constituents rendered these PFAS remediation technologies ineffective. Pilot and field-scale data from recent studies have shown a great potential of PFAS to bio-accumulate and distribute within plant compartments suggesting that phytoremediation could be a potential remediation technology to clean up PFAS contaminated soils. Even though several studies have been performed on the uptake and translocation of PFAS by different plant species, most of these studies are limited to agricultural crops and fruit species. In this review, the role of both aquatic and terrestrial plants in the phytoremediation of PFAS was discussed highlighting different mechanisms underlying the uptake of PFASs in the soil-plant and water-plant systems. This review further summarized a wide range of factors that influence the bioaccumulation and translocation of PFASs within plant compartments including both structural properties of PFASs and physiological properties of plant species. Even though phytoremediation appears to be a promising remediation technique, some limitations that reduced the feasibility of phytoremediation in the practical application have been emphasized in previous studies. Additional research directions are suggested, including advanced genetic engineering techniques and endophyte-assisted phytoremediation to upgrade the phytoremediation potential of plants for the successful removal of PFASs.

Occurrence, profiles, and ecotoxicity of poly- and perfluoroalkyl substances and their alternatives in global apex predators: A critical review

Certain poly- and perfluoroalkyl substances (PFASs) exhibit significant bioaccumulation/biomagnification behaviors in ecosystems. PFASs, such as perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS) and related precursors, have elicited attention from both public and national regulatory agencies, which has resulted in worldwide restrictions on their production and use. Apex predators occupy the top trophic positions in ecosystems and are most affected by the biomagnification behavior of PFASs. Meanwhile, the long lifespans of apex predators also lead to the high body burden of PFASs. The high body burden of PFASs might be linked to adverse health effects and even pose a potential threat to their reproduction. As seen in previous reviews of PFASs, knowledge is lacking between the current stage of the PFAS body burden and related effects in apex predators. This review summarized PFAS occurrence in global apex predators, including information on the geographic distribution, levels, profiles, and tissue distribution, and discussed the trophic transfer and ecotoxicity of PFASs. In the case where legacy PFASs were restricted under international convention, the occurrence of novel PFASs, such as 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) and perfluoroethylcyclohexane sulfonate (PFECHS), in apex predators arose as an emerging issue. Future studies should develop an effective analytical method and focus on the toxicity and trophic transfer behavior of novel PFASs.

Per and polyfluoroalkyl substances (PFAS) at high concentrations in neonatal Australian pinnipeds

Per and polyfluorinated substances (PFAS) exposure was investigated in Australian pinnipeds. Concentrations of 16 PFAS were measured in the livers of Australian sea lion (Neophoca cinerea), Australian fur seal (Arctocephalus pusillus doriferus) and a long-nosed Fur Seal (Arctocephalus forsteri) pup sampled between 2017 and 2020 from colonies in South Australia and Victoria. Findings reported in this study are the first documented PFAS concentrations in Australian pinnipeds. Median and observed range of values in ng/g wet weight were highest for perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) in the liver of N. cinerea (PFOS = 7.14, 1.00-16.9; PFOA = 2.73, 0.32-11.2; PFNA = 2.96, 0.61-8.22; n = 28), A. forsteri (PFOS = 15.98, PFOA = 2.02, PFNA = 7.86; n = 1) and A. p. doriferus (PFOS = 27.4, 10.5-2119; PFOA = 0.98, 0.32-52.2; PFNA = 2.50, 0.91-44.2; n = 20). PFAS concentrations in A. p. doriferus pups were significantly greater (p < 0.05) than in N. cinerea pups for all PFAS except PFOA and were of similar magnitude to those reported in northern hemisphere marine animals. These results demonstrate exposure differences in both magnitude and PFAS profiles for N. cinerea in South Australia and A. p. doriferus in Victoria. This study reports detectable PFAS concentrations in Australian pinniped pups indicating the importance of maternal transfer of these toxicants. As N. cinerea are endangered and recent declines in pup production has been reported for A. p. doriferus at the colony sampled, investigation of potential health impacts of these toxicants on Australian pinnipeds is recommended.

Characteristic distribution patterns of perfluoroalkyl substances in soils according to land-use types

In this study, a nationwide monitoring of perfluoroalkyl substances (PFAS) in soils was conducted for various land-use types around South Korea, such as industrial complexes, landfills, farmlands, mountains, and woodlands. The ∑₁₅PFAS concentrations in soil samples ranged from 0.175 to 11.7 ng/g dry weight (dw) (median 2.39 ng/g dw). The soil samples from industrial complexes (0.346-11.7 ng/g dw; median 3.25 ng/g dw) and landfills (0.504-10.4 ng/g dw; median 2.13 ng/g dw) had higher median ∑₁₅PFAS concentrations than other regions (0.175-3.01 ng/g dw; median 1.15 ng/g dw). In the soil samples from industrial areas, the ∑₁₅PFAS concentrations ranged from 3.11 to 11.7 ng/g dw (median 6.32 ng/g dw) from the textile industries, 3.26-8.74 ng/g dw (median 6.20 ng/g dw) from the metal industries, 1.53-5.71 ng/g dw (median 3.38 ng/g) from the chemical industries, and 0.346-3.48 ng/g dw (median 2.39 ng/g dw) from the electronics industries. Perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and long chain perfluorinated carboxylic acids (PFCAs) between C9 and C12 were generally dominant in these soils. In particular, PFOS, perfluorohexane sulfonate (PFHxS), and PFCAs with ≤ C6 were more frequently found in soils from industrial complexes than from other land-use types. On the other hand, PFCAs between C7 and C12 had relatively high detection frequencies regardless of the soil type.

PFAS soil and groundwater contamination via industrial airborne emission and land deposition in SW Vermont and Eastern New York State, USA

In order to understand the extent to which airborne PFAS emission can impact soil and groundwater, we conducted a sampling campaign in areas of conserved forest lands near Bennington, VT/Hoosick Falls, NY. This has been home to sources of PFAS air-emissions from Teflon-coating operations for over 50 years. Since 2015, the Vermont and New York Departments of Environmental Conservation have documented ∼1200 residential wells and two municipal water systems across a 200 km2 area contaminated with perfluorooctanoic acid (PFOA). Given the large areal extent of the plume, and the fact that much of the contaminated area lies up-gradient and across rivers from manufactures, we seek to determine if groundwater contamination could have resulted primarily from air-emission, land deposition, and subsequent leaching to infiltrating groundwater. Sampling of soils and groundwater in the Green Mountain National Forest (GMNF) downwind of factories shows that both soil and groundwater PFOA contamination extend uninterrupted from inhabited areas into conserved forest lands. Groundwater springs and seeps in the GMNF located 8 km downwind, but >300 meters vertically above factories, contain up to 100 ppt PFOA. Our results indicate that air-emitted PFAS can contaminate groundwater and soil in areas outside of those normally considered down-gradient of a source with respect to regional groundwater flow.

Hydrothermal Alkaline Treatment for Destruction of Per- and Polyfluoroalkyl Substances in Aqueous Film-Forming Foam

The widespread use of aqueous film-forming foam (AFFF) for firefighting activities (e.g., fire training to extinguish fuel-based fires at aircraft facilities) has led to extensive groundwater and soil contamination by per- and polyfluoroalkyl substances (PFASs) that are highly recalcitrant to destruction using conventional treatment technologies. This study reports on the hydrothermal alkaline treatment of diverse PFASs present in AFFFs. Quantitative and semiquantitative high-resolution mass spectrometry analyses of PFASs demonstrate a rapid degradation of all 109 PFASs identified in two AFFFs (sulfonate- and fluorotelomer-based formulations) in water amended with an alkali (e.g., 1-5 M NaOH) at near-critical temperature and pressure (350 °C, 16.5 MPa). This includes per- and polyfluoroalkyl acids and a range of acid precursors. Most PFASs were degraded to nondetectable levels within 15 min, and the most recalcitrant perfluoroalkyl sulfonates were degraded within 30 min when treated with 5 M NaOH. ¹⁹F NMR spectroscopic analysis and fluoride ion analysis confirm the near-complete defluorination of PFASs in both dilute and concentrated AFFF mixtures, and no stable volatile organofluorine species were detected in reactor headspace gases by the gas chromatography-mass spectrometry analysis. These findings indicate a significant potential for application of hydrothermal treatment technologies to manage PFAS waste streams, including on-site treatment of unused AFFF chemical stockpiles, investigation-derived wastes, and concentrated source zone materials.

In silico exploration of hydroxylated polychlorinated biphenyls as estrogen receptor β ligands by 3D-QSAR, molecular docking and molecular dynamics simulations

Hydroxylated polychlorinated biphenyls (HO-PCBs), as the major metabolites of PCBs, have been reported to act as estrogen receptor β (ERβ) agonists. However, the chemical-biological interactions governing their activities toward ERβ have not been elucidated. Therefore, three dimensional quantitative structure-activity relationship (3D-QSAR), molecular docking and molecular dynamics (MD) simulations, to the best of our knowledge, for the first time were performed to explore the correlation between the structures and activities. The best 3D-QSAR model presented higher predictive ability (R²_cv=0.543, R²_pred=0.5793/R²_cv=0.543, R²_pred=0.6795) based on comparative molecular field analysis (CoMFA) and comparative similarity indices analysis (CoMSIA), respectively. At the same time, the derived contour maps indicated the important structural features required for improving the activity. Furthermore, molecular docking studies and MD simulations predicted the binding mode and the interactions between the ligand and the receptor. All the results would lead to a better understanding of the specific mechanism of HO-PCBs on estrogen receptor β (ERβ).Communicated by Ramaswamy H. Sarma.

PFAS Environmental Pollution and Antioxidant Responses: An Overview of the Impact on Human Field

Due to their unique properties, perfluorinated substances (PFAS) are widely used in multiple industrial and commercial applications, but they are toxic for animals, humans included. This review presents some available data on the PFAS environmental distribution in the world, and in particular in Europe and in the Veneto region of Italy, where it has become a serious problem for human health. The consumption of contaminated food and drinking water is considered one of the major source of exposure for humans. Worldwide epidemiological studies report the negative effects that PFAS have on human health, due to environmental pollution, including infertility, steroid hormone perturbation, thyroid, liver and kidney disorders, and metabolic disfunctions. In vitro and in vivo researches correlated PFAS exposure to oxidative stress effects (in mammals as well as in other vertebrates of human interest), produced by a PFAS-induced increase of reactive oxygen species formation. The cellular antioxidant defense system is activated by PFAS, but it is only partially able to avoid the oxidative damage to biomolecules.

Thermally Driven Separation of Perfluoroalkyl Substances with High Efficiency

Perfluoroalkyl substances (PFASs), such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), can contaminate the surface and groundwater. Common treatment strategies and adsorbents have low adsorption efficiencies and poor selectivity toward PFASs because of the extremely low surface energy of these compounds. This paper reports the use of a phenolic resin (PR) modified with perfluoroalkyl (PFA) segments and thermally sensitive poly(ethylene glycol) (PEG) segments (PR-PEG-PFA) to remove PFOA and PFOS from water. The modified PR microspheres captured >90% of PFASs and were insensitive to common anionic surfactants. By treating simulated wastewater six times with this material, the PFOA concentration in water was reduced from 1 ppm to 43 ppt (43 ng L^-1), showing that PR-PEG-PFA is a promising adsorbent for PFAS separation, recovery, and recycling.

Calcium signaling as a possible mechanism behind increased locomotor response in zebrafish larvae exposed to a human relevant persistent organic pollutant mixture or PFOS

Persistent organic pollutants (POPs) are widespread in the environment and their bioaccumulation can lead to adverse health effects in many organisms. Previously, using zebrafish as a model vertebrate, we found larvae exposed to a mixture of 29 POPs based on average blood levels from the Scandinavian population showed hyperactivity, and identified perfluorooctanesulfonic acid (PFOS) as the driving agent for the behavioral changes. In order to identify possible mechanisms, we exposed zebrafish larvae from 6 to 96 h post fertilization to the same mixture of POPs in two concentrations or a single PFOS exposure (0.55 and 3.83 μM) and performed behavioral tests and transcriptomics analysis. Behavioral alterations of exposed zebrafish larvae included hyperactivity and confirmed previously reported results. Transcriptomics analysis showed upregulation of transcripts related to muscle contraction that is highly regulated by the availability of calcium in the sarcoplasmic reticulum. Ingenuity pathway analysis showed that one of the affected pathways in larvae exposed to the POP mixture and PFOS was calcium signaling via the activation of the ryanodine receptors (RyR). Functional analyses with RyR inhibitors and behavioral outcomes substantiate these findings. Additional pathways affected were related to lipid metabolism in larvae exposed to the lower concentration of PFOS. By using omics technology, we observed that the altered behavioral pattern in exposed zebrafish larvae may be controlled directly by mechanisms affecting muscle function rather than via mechanisms connected to neurotoxicity.

Perfluoroalkyl substances (PFASs) in white whales (Delphinapterus leucas) from Svalbard - A comparison of concentrations in plasma sampled 15 years apart

The objective of the present study was to investigate recent concentrations of perfluoroalkyl substances (PFASs) in white whales (Delphinapterus leucas) from Svalbard and compare them to concentrations found in white whales sampled from that same area 15 years ago. Plasma collected from live-captured white whales from two time periods (2013-2014, n = 9, and 1996-2001, n = 11) were analysed for 19 different PFASs. The 11 PFASs detected included seven C₈-C₁₄ perfluoroalkyl carboxylates (PFCAs) and three C₆-C₈ perfluoroalkyl sulfonates (PFSAs) as well as perfluorooctane sulfonamide (FOSA). Recent plasma concentrations (2013-2014) of the dominant PFAS in white whales, perfluorooctane sulfonate (PFOS; geometric mean = 22.8 ng/mL), was close to an order of magnitude lower than reported in polar bears (Ursus maritimus) from Svalbard. PFOS concentrations in white whales were about half the concentrations in harbour (Phoca vitulina) and ringed (Pusa hispida) seals, similar to hooded seals (Cystophora cristata) and higher than in walruses (Odobenus rosmarus) from that same area. From 1996 to 2001 to 2013-2014, plasma concentrations of PFOS decreased by 44%, whereas four C_9-12 PFCAs and total PFCAs increased by 35-141%. These results follow a similar trend to what has been reported in other studies of Arctic marine mammals from Svalbard. The most dramatic change has been the decline of PFOS concentrations since 2000, corresponding to the production phase-out of PFOS and related compounds in many countries around the year 2000 and a global restriction on these substances in 2009. Still, the continued dominance of PFOS in white whales, and increasing concentration trends for several PFCAs, even though exposure is relatively low, calls for continued monitoring of concentrations of both PFCAs and PFSAs and investigation of biological effects.

Per- and Polyfluoroalkyl Substances (PFAS) Neurotoxicity in Sentinel and Non-Traditional Laboratory Model Systems: Potential Utility in Predicting Adverse Outcomes in Human Health

Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals that were widely used in manufacturing and are now present in the environment throughout the world. It is known that various PFAS are quantifiable in human in blood, but potential adverse health outcomes remain unclear. Sentinel and non-traditional model species are useful to study potential toxicity of PFAS in order to understand the relationship between environmental and human health. Here, we present a critical review of studies on the neurotoxicity of PFAS in sentinel and non-traditional laboratory model systems, including Caenorhabditis elegans (nematode), Dugesia japonica (planarian), Rana pipiens (frogs), Danio rerio and Oryzias melastigma (fish), and Ursus maritimus (polar bears). PFAS have been implicated in developmental neurotoxicity in non-traditional and traditional model systems as well as sentinel species, including effects on neurotransmitter levels, especially acetylcholine and its metabolism. However, further research on the mechanisms of toxicity needs to be conducted to determine if these chemicals are affecting organisms in a similar manner. Overall, findings tend to be similar among the various species, but bioaccumulation may vary, which needs to be taken into account in future studies by quantifying target organ concentrations of PFAS to better compare different species. Furthermore, data on the majority of PFAS is lacking in neurotoxicity testing, and additional studies are needed to corroborate findings thus far.

Temporal Trends in Per- and Polyfluoroalkyl Substances in Bottlenose Dolphins (Tursiops truncatus) of Indian River Lagoon, Florida and Charleston, South Carolina

Temporal trends in plasma concentrations of per- and polyfluoroalkyl substances (PFAS) in free-ranging bottlenose dolphins (Tursiops truncatus) inhabiting two geographic areas: Indian River Lagoon, Florida over the years 2003-2015 and the waters surrounding Charleston, South Carolina over 2003-2013, were examined. Nine PFAS met the inclusion criteria for analysis based on percent of values below level of detection and sampling years. Proportionate percentiles parametric quantile regression assuming lognormal distributions was used to estimate the average ratio of PFAS concentrations per year for each chemical. Plasma concentrations decreased over time for perfluorodecanoate (PFDA), perfluorohexane sulfonate (PFHxS), perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and perfluoroundecanoate (PFUnDA) in both locations. Perfluorononanoate (PFNA) decreased with time in Indian River Lagoon dolphins. Perfluorododecanoate (PFDoDA) concentrations significantly increased over time among female Indian River Lagoon dolphins. Regulation and phaseout of specific PFAS groups may have led to the decreasing levels of those PFAS and increasing levels of other replacement PFAS.

Snow buntings (Plectrophenax nivealis) as bio-indicators for exposure differences to legacy and emerging persistent organic pollutants from the Arctic terrestrial environment on Svalbard

Eggs of snow buntings (Plectrophenax nivealis) were applied as a bio-indicator to examine differences in exposure to legacy persistent organic pollutants (POPs) and perflouroalkyl subtances (PFAS) from the terrestrial environment surrounding the settlements of Longyearbyen, Barentsburg and Pyramiden on Svalbard, Norway. Significantly higher concentrations of summed polychlorinated biphenyls (sumPCB7) in eggs collected from Barentsburg (2980 ng/g lipid weight (lw)) and Pyramiden (3860 ng/g lw) compared to Longyearbyen (96 ng/g lw) are attributed to local sources of PCBs within these settlements. Similar findings were observed for p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) where higher median concentrations observed in Pyramiden (173 ng/g lw) and Barentsburg (75 ng/g lw) compared to Longyearbyen (48 ng/g lw) may be influenced by guano inputs from breeding seabird populations, although other point sources cannot be ruled out. Concentrations of perfluorooctane sulphonate (PFOS) and several perfluorinated carboxylic acids (PFCAs) in snow bunting eggs were found to be statistically higher in the populated settlements of Longyearbyen and Barentsburg compared to the abandoned Pyramiden. Narrow foraging ranges of snow buntings during breeding season was useful in assessing point sources of exposure for PCBs and PFAS at particular sites with extreme differences observed between nest locations. SumPCB7 concentrations ranged from 2 μg/g ww to below detection limits between nest sites located less than a kilometer from each other in Pyramiden. Similar findings were observed in Longyearbyen, where several PFCAs ranged from 2 to 55 times higher between nest sites with similar spatial distances. These findings indicate that snow buntings can be a useful bio-indicator offering high spatial resolution for contaminant source apportionment in terrestrial environments on Svalbard.

State of knowledge on current exposure, fate and potential health effects of contaminants in polar bears from the circumpolar Arctic

The polar bear (Ursus maritimus) is among the Arctic species exposed to the highest concentrations of long-range transported bioaccumulative contaminants, such as halogenated organic compounds and mercury. Contaminant exposure is considered to be one of the largest threats to polar bears after the loss of their Arctic sea ice habitat due to climate change. The aim of this review is to provide a comprehensive summary of current exposure, fate, and potential health effects of contaminants in polar bears from the circumpolar Arctic required by the Circumpolar Action Plan for polar bear conservation. Overall results suggest that legacy persistent organic pollutants (POPs) including polychlorinated biphenyls, chlordanes and perfluorooctane sulfonic acid (PFOS), followed by other perfluoroalkyl compounds (e.g. carboxylic acids, PFCAs) and brominated flame retardants, are still the main compounds in polar bears. Concentrations of several legacy POPs that have been banned for decades in most parts of the world have generally declined in polar bears. Current spatial trends of contaminants vary widely between compounds and recent studies suggest increased concentrations of both POPs and PFCAs in certain subpopulations. Correlative field studies, supported by in vitro studies, suggest that contaminant exposure disrupts circulating levels of thyroid hormones and lipid metabolism, and alters neurochemistry in polar bears. Additionally, field and in vitro studies and risk assessments indicate the potential for adverse impacts to polar bear immune functions from exposure to certain contaminants.

Temporal Trends of Persistent Organic Pollutants in Barents Sea Polar Bears ( Ursus maritimus) in Relation to Changes in Feeding Habits and Body Condition

Temporal trends of persistent organic pollutants (POPs: PCBs, OH-PCBs, p, p'-DDE, HCB, β-HCH, oxychlordane, BDE-47, and 153) in relation to changes in feeding habits and body condition in adult female polar bears ( Ursus maritimus) from the Barents Sea subpopulation were examined over 20 years (1997-2017). All 306 samples were collected in the spring (April). Both stable isotope values of nitrogen (δ¹⁵N) and carbon (δ¹³C) from red blood cells declined over time, with a steeper trend for δ¹³C between 2012 and 2017, indicating a decreasing intake of marine and high trophic level prey items. Body condition, based on morphometric measurements, had a nonsignificant decreasing tendency between 1997 and 2005, and increased significantly between 2005 and 2017. Plasma concentrations of BDE-153 and β-HCH did not significantly change over time, whereas concentrations of Σ₄PCB, Σ₅OH-PCB, BDE-47, and oxychlordane declined linearly. Concentrations of p, p'-DDE and HCB, however, declined until 2012 and 2009, respectively, and increased thereafter. Changes in feeding habits and body condition did not significantly affect POP trends. The study indicates that changes in diet and body condition were not the primary driver of POPs in polar bears, but were controlled in large part by primary and/or secondary emissions of POPs.

Legacy and Emerging Persistent Organic Pollutants (POPs) in Terrestrial Compartments in the High Arctic: Sorption and Secondary Sources

Legacy persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and emerging perfluoroalkyl substances (PFASs) were measured in vegetation and soil samples collected at remote lakes in the Canadian High Arctic. Field studies were carried out in 2015 and 2016 to assess concentrations of POPs, study the relevant sorbing phases, and determine whether Arctic soils were sinks or sources of legacy POPs to the atmosphere and to neighboring lakes. The patterns of legacy POPs in vegetation and soils were dominated by low molecular weight PCB congeners along with OCPs, confirming the importance of long-range atmospheric transport. Lipid and non-lipid organic matter was a key determinant of legacy POPs in Arctic vegetation. Soil organic matter was the main descriptor of hydrophobic PCBs and OCPs in soils, while soil inorganic carbon content, was an important driver of the sorption of PFASs in soils. While contaminant concentrations were low in soil and vegetation, higher PCBs and PFOS organic and inorganic carbon-normalized concentrations were found at Resolute Lake indicating the presence of local sources of contamination. Comparison of fugacities of PCBs in soil and air from Resolute Lake indicated soils as net sources of PCBs to the atmosphere.

Effects of biometrics, location and persistent organic pollutants on blood clinical-chemical parameters in polar bears (Ursus maritimus) from Svalbard, Norway

In the present study, blood clinical-chemical parameters (BCCPs) were analysed in 20 female and 18 male Svalbard polar bears (Ursus maritimus) captured in spring 2007. The aim was to study how age, body condition (BC), biometrics, plasma lipid content and geographical location may confound the relationship between persistent organic pollutants (POPs) including PCBs, HCB, chlordanes, DDTs, HCHs, mirex and OH-PCBs and the concentrations of 12 specific BCCPs (hematocrit [HCT], hemoglobin [HB], aspartate aminotransferase [ASAT], alanine aminotransferase [ALAT], γ-glutamyltransferase [GGT], creatine kinase [CK], triglycerides [TG], cholesterol [CHOL], high-density lipoprotein [HDL], creatinine (CREA], urea, potassium (K]), and to investigate if any of these BCCPs may be applied as potential biomarkers for POP exposure in polar bears. Initial PCA and O-PLS modelling showed that age, lipids, BC and geographical location (longitude and latitude) were important parameters explaining BCCPs in females. Following subsequent partial correlation analyses correcting for age and lipids, multiple POPs in females were still significantly correlated with HCT and HDL (all p < 0.05). In males, age, BM, BC and longitude were important parameters explaining BCCPs. Following partial correlation analyses correcting for age, biometrics, lipids and longitude in males, multiple POPs were significantly correlated with HCT, ASAT, GGT and CHOL (all p < 0.05). In conclusion, several confounding parameters has to be taken into account when studying the relations between BCCPs and POPs in polar bears. When correcting for these, in particular HCT may be used as a simple cost-efficient biomarker of POP exposure in polar bears. Furthermore, decreasing HDL concentrations and increasing CHOL concentration with increasing POP concentrations may indicate responses related to increased risk of cardiovascular disease. We therefore suggest to further study POP exposure and lipidome response to increase knowledge of the risk of cardiometabolic syndrome in polar bears.

Choose Your Poison-Space-Use Strategy Influences Pollutant Exposure in Barents Sea Polar Bears

Variation in space-use is common within mammal populations. In polar bears, Ursus maritimus, some individuals follow the sea ice (offshore bears) whereas others remain nearshore yearlong (coastal bears). We studied pollutant exposure in relation to space-use patterns (offshore vs coastal) in adult female polar bears from the Barents Sea equipped with satellite collars (2000-2014, n = 152). First, we examined the differences in home range (HR) size and position, body condition, and diet proxies (nitrogen and carbon stable isotopes, n = 116) between offshore and coastal space-use. Second, we investigated how HR, space-use, body condition, and diet were related to plasma concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) ( n = 113), perfluoroalkyl substances (PFASs; n = 92), and hydroxylated-PCBs ( n = 109). Offshore females were in better condition and had a more specialized diet than did coastal females. PCBs, OCPs, and hydroxylated-PCB concentrations were not related to space-use strategy, yet PCB concentrations increased with increasing latitude, and hydroxylated-PCB concentrations were positively related to HR size. PFAS concentrations were 30-35% higher in offshore bears compared to coastal bears and also increased eastward. On the basis of the results we conclude that space-use of Barents Sea female polar bears influences their pollutant exposure, in particular plasma concentrations of PFAS.

A rationally designed perfluorinated host for the extraction of PFOA from water utilising non-covalent interactions

Three hosts for the encapsulation of perfluorooctanoic acid have been synthesized. The host:guest complexes have been characterized by multinuclear NMR spectroscopy in solution and the solid state.

Relationships between POPs, biometrics and circulating steroids in male polar bears (Ursus maritimus) from Svalbard

The aim of this study was to determine the effects of persistent organic pollutants (POPs) and biometric variables on circulating levels of steroid hormones (androgens, estrogens and progestagens) in male polar bears (Ursus maritimus) from Svalbard, Norway (n = 23). Levels of pregnenolone (PRE), progesterone (PRO), androstenedione (AN), dehydroepiandrosterone (DHEA), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2) and 17β-estradiol (βE2) were quantified in polar bear serum by gas chromatography tandem mass spectrometry (GC-MS/MS), while POPs were measured in plasma. Subsequently, associations between hormone concentrations (9 steroids), POPs (21 polychlorinated biphenyls (PCBs), 8 OH-PCBs, 8 organochlorine pesticides (OCPs) and OCP metabolites, and 2 polybrominated diphenyl ethers (PBDEs)) and biological variables (age, head length, body mass, girth, body condition index), capture date, location (latitude and longitude), lipid content and cholesterol levels were examined using principal component analysis (PCA) and orthogonal projections to latent structures (OPLS) modelling. Average concentrations of androgens, estrogens and progestagens were in the range of 0.57-83.7 (0.57-12.4 for subadults, 1.02-83.7 for adults), 0.09-2.69 and 0.57-2.44 nmol/L, respectively. The steroid profiles suggest that sex steroids were mainly synthesized through the Δ-4 pathway in male polar bears. The ratio between androgens and estrogens significantly depended on sexual maturity with androgen/estrogen ratios being approximately 60 times higher in adult males than in subadult males. PCA plots and OPLS models indicated that TS was positively related to biometrics, such as body condition index in male polar bears. A negative relationship was also observed between POPs and DHT. Consequently, POPs and body condition may potentially affect the endocrinological function of steroids, including development of reproductive tissues and sex organs and the general condition of male polar bears.

Emission Changes Dwarf the Influence of Feeding Habits on Temporal Trends of Per- and Polyfluoroalkyl Substances in Two Arctic Top Predators

We monitored concentrations of per- and polyfluoroalkyl substances (PFASs) in relation to climate-associated changes in feeding habits and food availability in polar bears (Ursus maritimus) and arctic foxes (Vulpes lagopus) (192 plasma and 113 liver samples, respectively) sampled from Svalbard, Norway, during 1997-2014. PFASs concentrations became greater with increasing dietary trophic level, as bears and foxes consumed more marine as opposed to terrestrial food, and as the availability of sea ice habitat increased. Long-chained perfluoroalkyl carboxylates (PFCAs) in arctic foxes decreased with availability of reindeer carcasses. The ∼9-14% yearly decline of C_6-8 perfluoroalkyl sulfonates (PFSAs) following the cease in C_6-8 PFSA precursor production in 2001 indicates that the peak exposure was mainly a result of atmospheric transport of the volatile precursors. However, the stable PFSA concentrations since 2009-2010 suggest that Svalbard biota is still exposed to ocean-transported PFSAs. Long-chain ocean-transported PFCAs increased 2-4% per year and the increase in C_12-14 PFCAs in polar bears tended to level off since ∼2009. Emerging short-chain PFASs showed no temporal changes. Climate-related changes in feeding habits and food availability moderately affected PFAS trends. Our results indicate that PFAS concentrations in polar bears and arctic foxes are mainly affected by emissions.

Diet and metabolic state are the main factors determining concentrations of perfluoroalkyl substances in female polar bears from Svalbard

Perfluoroalkyl substances (PFASs) have been detected in organisms worldwide, including Polar Regions. The polar bear (Ursus maritimus), the top predator of Arctic marine ecosystems, accumulates high concentrations of PFASs, which may be harmful to their health. The aim of this study was to investigate which factors (habitat quality, season, year, diet, metabolic state [i.e. feeding/fasting], breeding status and age) predict PFAS concentrations in female polar bears captured on Svalbard (Norway). We analysed two perfluoroalkyl sulfonates (PFSAs: PFHxS and PFOS) and C₈-C₁₃ perfluoroalkyl carboxylates (PFCAs) in 112 plasma samples obtained in April and September 2012-2013. Nitrogen and carbon stable isotope ratios (δ¹⁵N, δ¹³C) in red blood cells and plasma, and fatty acid profiles in adipose tissue were used as proxies for diet. We determined habitat quality based on movement patterns, capture position and resource selection functions, which are models that predict the probability of use of a resource unit. Plasma urea to creatinine ratios were used as proxies for metabolic state (i.e. feeding or fasting state). Results were obtained from a conditional model averaging of 42 general linear mixed models. Diet was the most important predictor of PFAS concentrations. PFAS concentrations were positively related to trophic level and marine diet input. High PFAS concentrations in females feeding on the eastern part of Svalbard, where the habitat quality was higher than on the western coast, were likely related to diet and possibly to abiotic factors. Concentrations of PFSAs and C₈-C₁₀ PFCAs were higher in fasting than in feeding polar bears and PFOS was higher in females with cubs of the year than in solitary females. Our findings suggest that female polar bears that are exposed to the highest levels of PFAS are those 1) feeding on high trophic level sea ice-associated prey, 2) fasting and 3) with small cubs.

The design of an environmentally relevant mixture of persistent organic pollutants for use in in vivo and in vitro studies

Amongst the substances listed as persistent organic pollutants (POP) under the Stockholm Convention on Persistent Organic Pollutants (SCPOP) are chlorinated, brominated, and fluorinated compounds. Most experimental studies investigating effects of POP employ single compounds. Studies focusing on effects of POP mixtures are limited, and often conducted using extracts from collected specimens. Confounding effects of unmeasured substances in such extracts may bias the estimates of presumed causal relationships being examined. The aim of this investigation was to design a model of an environmentally relevant mixture of POP for use in experimental studies, containing 29 different chlorinated, brominated, and perfluorinated compounds. POP listed under the SCPOP and reported to occur at the highest levels in Scandinavian food, blood, or breast milk prior to 2012 were selected, and two different mixtures representing varying exposure scenarios constructed. The in vivo mixture contained POP concentrations based upon human estimated daily intakes (EDIs), whereas the in vitro mixture was based upon levels in human blood. In addition to total in vitro mixture, 6 submixtures containing the same concentration of chlorinated + brominated, chlorinated + perfluorinated, brominated + perfluorinated, or chlorinated, brominated or perfluorinated compounds only were constructed. Using submixtures enables investigating the effect of adding or removing one or more chemical groups. Concentrations of compounds included in feed and in vitro mixtures were verified by chemical analysis. It is suggested that this method may be utilized to construct realistic mixtures of environmental contaminants for toxicity studies based upon the relative levels of POP to which individuals are exposed.

Closing the Mass Balance on Fluorine on Papers and Textiles

Papers and textiles that are treated with per- and polyfluoroalkyl substances (PFASs) are sources of human and environmental exposure. Data for individual PFASs, such as perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA), are not placed into the context of total fluorine for papers and textiles. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to quantify volatile and ionic PFASs, respectively, and the total oxidizable precursor (TOP) assay was used to quantify precursors that form perfluoroalkyl carboxylates. Molar sums of PFASs obtained by GC-MS, LC-MS/MS, and precursors were compared to total fluorine (nmol F/cm²) determined by particle-induced gamma ray emission (PIGE) spectroscopy, measured before and after extraction. Volatile and ionic PFASs and unknown precursors accounted for 0-2.2%, 0-0.41%, and 0.021-14%, respectively, of the total nmol F/cm² determined by PIGE. After extraction, papers and textiles retained 64 ± 28% to 110 ± 30% of the original nmol F/cm² as determined by PIGE, indicating that the majority of fluorine remains associated with the papers and textiles. The sum of PFASs in the volatile, ionic, and precursor fraction, and total fluorine after extraction indicate that mass balance was achieved (within analytical error) of the initial total fluorine measured by PIGE.

Maternal exposure to a mixture of persistent organic pollutants (POPs) affects testis histology, epididymal sperm count and induces sperm DNA fragmentation in mice

Persistent organic pollutants (POPs) are widespread throughout the environment and some are suspected to induce reproductive toxicity. As animals and humans are exposed to complex mixtures of POPs, it is reasonable to assess how such mixtures could interact with the reproductive system. Our aim is to investigate how maternal exposure to a mixture of 29 different persistent organic pollutants, formulated to mimic the relative POP levels in the food basket of the Scandinavian population, could alter reproductive endpoints. Female mice were exposed via feed from weaning, during pregnancy and lactation in 3 exposure groups (control (C), low (L) and high (H)). Testicular morphometric endpoints, epididymal sperm concentration and sperm DNA integrity were assessed in adult male offspring. We found that the number of tubules, proportion of tubule compartments and epididymal sperm concentration significantly decreased in both POP exposed groups. Epididymal sperm from both POP exposed groups showed increased DNA fragmentation. It is concluded that maternal exposure to a defined POP mixture relevant to human exposure can affect testicular development, sperm production and sperm chromatin integrity.

Chlorinated Polyfluoroalkyl Ether Sulfonic Acids in Matched Maternal, Cord, and Placenta Samples: A Study of Transplacental Transfer

Currently, information regarding concentrations of chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs) in human placenta does not exist. The main objective of this study was to assess the occurrence and distribution of two Cl-PFESAs, 6:2 Cl-PFESA and 8:2 Cl-PFESA, in maternal serum, umbilical cord serum, and placenta to better assess the transport pathways related to human prenatal exposure. The widely studied perfluorooctanesulfonate (PFOS) was studied for comparison. This study was a hospital-based survey involving quantitative determination of Cl-PFESA and PFOS concentrations in maternal serum (n = 32), cord serum (n = 32), and placenta (n = 32) samples from women in Wuhan, China. The results indicate that Cl-PFESAs can efficiently be transported across placenta, with median exposure levels of 0.60 and 0.01 ng/mL for 6:2 Cl-PFESA and 8:2 Cl-PFESA in the cord sera, respectively. Concentrations of the target compounds in maternal sera, cord sera, and placentas decreased in the following order: PFOS > 6:2 Cl-PFESA > 8:2 Cl-PFESA. Similar patterns were observed in maternal sera, cord sera, and placentas for Cl-PFESAs, with concentrations decreasing in the following order: maternal sera > cord sera > placentas. Significant correlations were observed among 6:2 Cl-PFESA, 8:2 Cl-PFESA, and PFOS concentrations in the maternal serum, cord serum, and placenta samples (r > 0.7; p < 0.001). The median value of R_CM (ratio of cord serum to maternal serum concentration) of 6:2 Cl-PFESA was 0.403, indicating a relatively high (∼40%) placental transfer efficiency. 8:2 Cl-PFESA was transported across placenta to a greater extent than 6:2 Cl-PFESA was, likely because of its higher hydrophobicity and lower plasma protein binding affinity. To the best of our knowledge, this is the first study to report the occurrence and distribution of 6:2 Cl-PFESA and 8:2 Cl-PFESA in human placenta. The findings improve our understanding of the mechanisms of transplacental transfer and neonatal exposure to these important PFOS alternatives.

Maternal transfer of perfluoroalkyl substances in hooded seals

The role of milk in the transfer of perfluoroalkyl substances (PFASs) to offspring is not well known in wildlife. Eight PFASs were quantified in plasma and milk in mother-pup pairs of hooded seals (Cystophora cristata) during the nursing period, and the role of milk in the transfer process was analyzed. Hooded seal was chosen because of its short lactation period (3-4 d), during which the pup feeds only on milk. Placental or lactation transfer would thus be the only source of PFAS in the pup. Of the 8 PFASs analyzed (Σ₈ PFAS), 7 were found in all samples; therefore, milk is a source to PFASs in pups. Perfluorooctane sulfonate was the dominant PFAS in all samples. Mean Σ₈ PFAS concentrations were 6.0 ng/g protein (36 ng/g wet wt) in maternal plasma, 0.77 ng/g protein (3.2 ng/g wet wt) in milk, and 12 ng/g protein (66 ng/g wet wt) in pup plasma. Measured concentrations in plasma were within ranges previously reported from other seal species, below known toxicity thresholds for experimental rodents. Individual PFASs differed in transfer efficiency from mother to pup, depending on carbon chain lengths, with the lowest relative transfer for the intermediate-chained PFASs (C₉ -C₁₀ ). The results show maternal transfer of PFASs via both milk and the placenta, of which placental transfer is the dominant pathway. Environ Toxicol Chem 2017;36:763-770. © 2016 SETAC.

A Mixture of Persistent Organic Pollutants and Perfluorooctanesulfonic Acid Induces Similar Behavioural Responses, but Different Gene Expression Profiles in Zebrafish Larvae

Persistent organic pollutants (POPs) are widespread in the environment and some may be neurotoxic. As we are exposed to complex mixtures of POPs, we aimed to investigate how a POP mixture based on Scandinavian human blood data affects behaviour and neurodevelopment during early life in zebrafish. Embryos/larvae were exposed to a series of sub-lethal doses and behaviour was examined at 96 h post fertilization (hpf). In order to determine the sensitivity window to the POP mixture, exposure models of 6 to 48 and 48 to 96 hpf were used. The expression of genes related to neurological development was also assessed. Results indicate that the POP mixture increases the swimming speed of larval zebrafish following exposure between 48 to 96 hpf. This behavioural effect was associated with the perfluorinated compounds, and more specifically with perfluorooctanesulfonic acid (PFOS). The expression of genes related to the stress response, GABAergic, dopaminergic, histaminergic, serotoninergic, cholinergic systems and neuronal maintenance, were altered. However, there was little overlap in those genes that were significantly altered by the POP mixture and PFOS. Our findings show that the POP mixture and PFOS can have a similar effect on behaviour, yet alter the expression of genes relevant to neurological development differently.

Sea ice-associated decline in body condition leads to increased concentrations of lipophilic pollutants in polar bears (Ursus maritimus) from Svalbard, Norway

Global climate changes are magnified in the Arctic and are having an especially dramatic effect on the spatial and temporal distribution and the thickness traits of sea ice. Decline of Arctic sea ice may lead to qualitative and/or quantitative changes in diet and reduced body condition (i.e. adipose tissue stores) of ice-associated apex predators such as polar bears (Ursus maritimus). This may further affect their tissue concentrations of lipophilic pollutants. We determined how variations in adipose tissue stores associated to both breeding status and spatial changes in sea ice conditions and diet influence concentrations and biotransformation of lipophilic persistent organic pollutants (POPs). We collected 112 blood and fat samples from female polar bears (Ursus maritimus) of different breeding status (alone, with cubs of the year, or with yearlings) during two seasons (April and September) in 2012 and 2013 at three locations of Svalbard, Norway, with contrasted sea ice conditions. We inferred diet from nitrogen and carbon stable isotope ratios in red blood cells and fatty acid composition in adipose tissue. Relative to diet, body condition, which was negatively related to sea ice extent at both temporal and spatial scales, was the most important predictor for concentrations of POPs in plasma and fat, whereas diet showed a minor influence. Additionally, fatter females were more efficient at biotransforming PCBs than were leaner ones. Breeding status influenced the concentrations of less lipophilic compounds such as β-hexachlorocyclohexane, which were lower in females with yearlings, probably due to excretion into milk and subsequent offloading to young. In conclusion, our results indicate that declining sea ice indirectly leads to increased concentrations of lipophilic pollutants in polar bears mediated through reduced feeding opportunities and declining body condition rather than changes in diet composition.

Association between DNA methylation profiles in leukocytes and serum levels of persistent organic pollutants in Dutch men

Consumption of polluted fish may lead to high levels of persistent organic pollutants (POPs) in humans, potentially causing adverse health effects. Altered DNA methylation has been suggested as a possible contributor to a variety of adverse health effects. The aim of this study was to evaluate the relationship between serum POP levels (dioxins, polychlorobiphenyls, and perfluoroctane sulphonate) and DNA methylation. We recruited a total of 80 Dutch men who regularly consumed eel from either low- or high-polluted areas, and subsequently had normal or elevated POP levels. Clinical parameters related to e.g. hormone levels and liver enzymes were measured as biomarkers for adverse health effects. The Infinium 450K BeadChip was used to assess DNA methylation in a representative subset of 34 men. We identified multiple genes with differentially methylated regions (DMRs; false discovery rate <0.05) related to POP levels. Several of these genes are involved in carcinogenesis (e.g. BRCA1, MAGEE2, HOXA5), the immune system (e.g. RNF39, HLA-DQB1), retinol homeostasis (DHRS4L2), or in metabolism (CYP1A1). The DMRs in these genes show mean methylation differences up to 7.4% when comparing low- and high-exposed men, with a mean difference up to 14.4% for single positions within a DMR. Clinical parameters were not significantly associated with serum POP levels. This is the first explorative study investigating extensive DNA methylation in relation to serum POP levels among men. We observed that elevated POP levels are associated with aberrant DNA methylation profiles in adult men who consumed high-polluted eel. These preliminary findings warrant further confirmation in other populations.

Accumulation of persistent organic pollutants in consumers of eel from polluted rivers compared to marketable eel

Globally, many river sediments are seriously contaminated with persistent organic pollutants (POPs) known to accumulate in aquatic food. In the Netherlands, toxicological risks of human exposure to dioxins and dioxin-like compounds led to a ban on eel fishing in the Rhine-Meuse delta. The aim of this study is to investigate differences in serum POP levels in consumers of eel from high-polluted areas and consumers of eel from low-polluted areas or aquaculture. In total 80 Dutch men were included, aged 40-70 years, with a habitual eel consumption of at least one portion (150 g) per month. Total levels of dioxins and dioxin-like compounds were measured in serum of all participants with the DR CALUX bioassay, validated with GC-MS. For a subgroup of 38 participants extensive POP measurements were performed. We revealed that consumption of eel from polluted rivers resulted in 2.5 and up to 10 times increased levels of dioxins and polychlorinated biphenyls (PCBs) respectively compared to controls. The highest PCB levels were detected for PCB 153, with a median level of 896 ng/g lipid and a maximum level of 5000 ng/g lipid in the high-exposed group. Furthermore, hydroxylated PCB metabolites (OH-PCBs: sum of 4-OH-CB107, 4-OH-CB146, 4'-OH-CB172, and 4-OH-CB187) were 8 times higher in men who consumed eel from polluted areas, and detected at levels (median 4.5 ng/g ww) reported to cause adverse health effects. Also, the majority of the perfluoroalkyl substances (PFASs) were significantly higher in consumers of eel from pullulated areas. In conclusion, this study is the first to reveal that (past) consumption of eel from polluted rivers resulted in high body burdens of dioxins, PCBs, OH-PCBs and PFASs. We confirmed the predictions made in a former risk assessment, and the high levels of dioxins and dioxin-like compounds as well as the OH-PCBs are of health concern.

Perfluoroalkylphosphinic Acids in Northern Pike (Esox lucius), Double-Crested Cormorants (Phalacrocorax auritus), and Bottlenose Dolphins (Tursiops truncatus) in Relation to Other Perfluoroalkyl Acids

Perfluoroalkyl phosphinic acids (PFPIAs) are perfluoroalkyl acids (PFAAs) that are used for their surfactant properties in a variety of applications, resulting in their presence in environmental waters; however, they have not been widely studied in biota. A survey of PFPIAs was conducted in fish, dolphins, and birds from various locations in North America. Northern pike (Esox lucius) were collected at two locations in 2011 near Montréal Island in the St. Lawrence River, Canada, double-crested cormorants (Phalacrocorax auritus) were collected from bird colonies in the Great Lakes in 2010-2012, and bottlenose dolphins (Tursiops truncatus) from Sarasota Bay, FL and Charleston Harbor, SC were sampled in 2004-2009. PFPIAs had a detection frequency of 100% in all animals. This is the first report of PFPIAs in fish, dolphin, and bird plasma. Total PFPIA levels (mean ± standard deviation, 1.87 ± 2.17 ng/g wet weight (ww), range of 0.112-15.3 ng/g ww) were 1-2 orders of magnitude lower than those of perfluoroalkyl carboxylates (PFCA) and perfluoroalkanesulfonates (PFSA) in the same samples. The predominant congeners were 6:8 PFPIA (cormorants and pike) and 6:6 PFPIA (dolphins). Total PFPIAs in cormorants from Hamilton Harbour (5.02 ± 2.80 ng/g ww) were statistically higher than in other areas and taxonomic groups. The ubiquity of PFPIAs warrants further research on sources and effects of these unique compounds.

Spatial and temporal trends in perfluoroalkyl substances (PFASs) in ringed seals (Pusa hispida) from Svalbard

This study investigates concentrations of perfluoroalkyl carboxylates (PFCAs), perfluoroalkyl sulfonates (PFSAs) and perfluoroalkane sulfonamides (FASA) in plasma from ringed seals sampled in the period 1990-2010 (n = 71) in Svalbard, Norway. Perfluorooctane sulfonate was dominant among the perfluoroalkyl substances. PFCAs were dominated by perfluoroundecanoate followed by perfluorononanoate. C4C8 PFCAs and perfluorooctane sulfonamide (FOSA) were detected in ≤42% of the samples. PFSA and PFCA concentrations were higher in seals sampled from Kongsfjorden, a fjord influenced by strong inflows of Atlantic Water compared to seals from fjords dominated by Arctic Water (e.g. Billefjorden). Sex, age and body condition of the seals did not influence PFAS concentrations. Due to the confounding effect of year and sampling area, temporal trends were assessed only in seals sampled from Kongsfjorden (5 years, n = 51). PFHxS and PFOS concentrations did not show significant linear trends during the whole study period, but a decrease was observed since 2004. Concentrations of all of the detected PFCAs (C9C13 PFCAs) increased until 2004 after which they have declined or stabilized.

Hair Mercury Concentrations in Western Hudson Bay Polar Bear Family Groups

Methylmercury is one of the more toxic forms of mercury (Hg), the biomagnification of which is prevalent in the Arctic where apex predators such as polar bears (Ursus maritimus) can carry high loads. The maternal transfer of contaminants to offspring is a concern, as offspring may be particularly sensitive to the effects of environmental pollutants during early development. However, few studies of polar bears report on Hg in dependent young. We examined hair total Hg (THg) concentrations in 24 polar bear family groups in western Hudson Bay: mother, cub-of-the-year (COY), yearling, and 2 year old. THg concentrations increased with bear age, with COYs having lower concentrations than other offspring groups (p ≤ 0.008). Using AICc-based regression models, we found maternal THg to be positively related to body condition and litter size, while overall offspring THg was positively related to maternal body condition in addition to being dependent on the sex and age of the offspring. COY THg concentrations were positively related to maternal THg while also depending on the sex of the offspring. Considering our results, future studies in polar bear ecotoxicology are encouraged to include offspring of different ages and sexes.

Properties, performance and associated hazards of state-of-the-art durable water repellent (DWR) chemistry for textile finishing

Following the phase-out of long-chain per- and polyfluoroalkyl substances (PFASs), the textile industry had to find alternatives for side-chain fluorinated polymer based durable water repellent (DWR) chemistries that incorporated long perfluoroalkyl side chains. This phase-out and subsequent substitution with alternatives has resulted in a market where both fluorinated and non-fluorinated DWRs are available. These DWR alternatives can be divided into four broad groups that reflect their basic chemistry: side-chain fluorinated polymers, silicones, hydrocarbons and other chemistries (includes dendrimer and inorganic nanoparticle chemistries). In this critical review, the alternative DWRs are assessed with regards to their structural properties and connected performance, loss and degradation processes resulting in diffuse environmental emissions, and hazard profiles for selected emitted substances. Our review shows that there are large differences in performance between the alternative DWRs, most importantly the lack of oil repellence of non-fluorinated alternatives. It also shows that for all alternatives, impurities and/or degradation products of the DWR chemistries are diffusively emitted to the environment. Our hazard ranking suggests that hydrocarbon based DWR is the most environmentally benign, followed by silicone and side-chain fluorinated polymer-based DWR chemistries. Industrial commitments to reduce the levels of impurities in silicone based and side-chain fluorinated polymer based DWR formulations will lower the actual risks. There is a lack of information on the hazards associated with DWRs, in particular for the dendrimer and inorganic nanoparticle chemistries, and these data gaps must be filled. Until environmentally safe alternatives, which provide the required performance, are available our recommendation is to choose DWR chemistry on a case-by-case basis, always weighing the benefits connected to increased performance against the risks to the environment and human health.

Chlorinated, brominated and fluorinated organic pollutants in African Penguin eggs: 30 years since the previous assessment

The African Penguin population has drastically declined over the last 100 years. Changes in food availability due to over-fishing and other oceanographic changes seem to be major causes. However, it has also been 30 years since organic pollutants as a potential factor have been assessed. We analysed penguin eggs collected in 2011 and 2012 from two breeding colonies 640 km apart: Robben Island near Cape Town on the Atlantic Ocean coast, and Bird Island near Port Elizabeth on the Indian Ocean coast of South Africa. We quantified organochlorine pesticides, brominated flame retardants, and perfluorinated compounds (PFCs). Compared to 30 years ago, concentrations of ΣDDT have remained about the same or slightly lower, while ΣPCBs declined almost four-fold. The use of DDT in malaria control is unlikely to have contributed. PFCs were detected in all eggs. Indications (non-significant) of eggshell thinning associated with ΣDDT and ΣPCB was found. It seems therefore that the concentrations of measured organic pollutants the African Penguin eggs are not contributing directly to its current demise, but concerns remain about thinner shells and desiccation. Effects of combinations of compounds and newer compounds cannot be excluded, as well as more subtle effects on reproduction, development, and behaviour.

Hydroxylated polychlorinated biphenyls decrease circulating steroids in female polar bears (Ursus maritimus)

As a top predator in the Arctic food chain, polar bears (Ursus maritimus) are exposed to high levels of persistent organic pollutants (POPs). Because several of these compounds have been reported to alter endocrine pathways, such as the steroidogenesis, potential disruption of the sex steroid synthesis by POPs may cause implications for reproduction by interfering with ovulation, implantation and fertility. Blood samples were collected from 15 female polar bears in Svalbard (Norway) in April 2008. The concentrations of nine circulating steroid hormones; dehydroepiandrosterone (DHEA), androstenedione (AN), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2), 17β-estradiol (βE2), pregnenolone (PRE) and progesterone (PRO) were determined. The aim of the study was to investigate associations among circulating levels of specific POP compounds and POP-metabolites (hydroxylated PCBs [OH-PCBs] and hydroxylated PBDEs [OH-PBDEs]), steroid hormones, biological and capture variables in female polar bears. Inverse correlations were found between circulating levels of PRE and AN, and circulating levels of OH-PCBs. There were no significant relationships between the steroid concentrations and other analyzed POPs or the variables capture date and capture location (latitude and longitude), lipid content, condition and body mass. Although statistical associations do not necessarily represent direct cause-effect relationships, the present study indicate that OH-PCBs may affect the circulating levels of AN and PRE in female polar bears and that OH-PCBs thus may interfere with the steroid homeostasis. Increase in PRO and a decrease in AN concentrations suggest that the enzyme CYP17 may be a potential target for OH-PCBs. In combination with natural stressors, ongoing climate change and contaminant exposure, it is possible that OH-PCBs may disturb the reproductive potential of polar bears.

Contaminant levels in the world's northernmost harbor seals (Phoca vitulina)

The world's northernmost harbor seal (Phoca vitulina) population, which inhabits Svalbard, Norway, constitutes a genetically distinct population. The present study reports concentrations of 14 PCBs, 5 chlordanes, p,p'-DDT, p,p'-DDE, hexachlorobenzene (HCB), mirex, and, α-, β-and γ-hexachlorocyclohexane (HCH) in blubber, and pentachlorophenol, 4-OH-heptachlorostyrene, 10 OH-PCBs and 14 perfluoroalkyl substances in plasma of live-captured harbor seals from this population (4 males, 4 females, 4 juveniles), sampled in 2009-2010. Concentrations of PCB 153, p,p'-DDE, oxychlordane, α-HCH and mirex and perfluoroalkyl sulfonates in Svalbard harbor seals were considerably lower than harbor seal from more southerly populations, while concentrations of HCB, OH-PCBs and perfluoroalkyl carboxylates were similar for harbor seals from Svalbard and southern areas. Concentrations of PCBs and pesticides in the Svalbard harbor seals were 60-90% lower than levels determined a decade ago in this same population. Current concentrations of legacy POPs are not considered a health risk to the harbor seals from Svalbard.

Effect of body condition on tissue distribution of perfluoroalkyl substances (PFASs) in Arctic fox (Vulpes lagopus)

Arctic animals undergo large seasonal fluctuations in body weight. The effect of body condition on the distribution and composition of 16 perfluoroalkyl substances (PFASs) was investigated in liver, blood, kidney, adipose tissue, and muscle of Arctic foxes (Vulpes lagopus) from Svalbard (n = 18, age 1-3 years). PFAS concentrations were generally highest in liver, followed by blood and kidney, while lowest concentrations were found in adipose tissue and muscle. Concentrations of summed perfluorocarboxylic acids and perfluoroalkyl sulfonates were five and seven times higher, respectively, in adipose tissue of lean compared to fat foxes. In addition, perfluorodecanoate (PFDA) and perfluoroheptanesulfonate (PFHpS) concentrations in liver, kidney, and blood, and, perfluorononanoate (PFNA) in liver and blood, were twice as high in the lean compared to the fat foxes. The ratio between perfluorooctane sulfonamide (FOSA) and its metabolite perfluorooctanesulfonate (PFOS) was lowest in liver, muscle, and kidney, while significantly higher proportions of FOSA were found in adipose tissue and blood. The results of the present study suggest that toxic potential of exposure to PFAS among other pollutants in Arctic mammals may increase during seasonal emaciation. The results also suggest that body condition should be taken into account when assessing temporal trends of PFASs.

Current concepts in neuroendocrine disruption

In the last few years, it has become clear that a wide variety of environmental contaminants have specific effects on neuroendocrine systems in fish, amphibians, birds and mammals. While it is beyond the scope of this review to provide a comprehensive examination of all of these neuroendocrine disruptors, we will focus on select representative examples. Organochlorine pesticides bioaccumulate in neuroendocrine areas of the brain that directly regulate GnRH neurons, thereby altering the expression of genes downstream of GnRH signaling. Organochlorine pesticides can also agonize or antagonize hormone receptors, adversely affecting crosstalk between neurotransmitter systems. The impacts of polychlorinated biphenyls are varied and in many cases subtle. This is particularly true for neuroedocrine and behavioral effects of exposure. These effects impact sexual differentiation of the hypothalamic-pituitary-gonadal axis, and other neuroendocrine systems regulating the thyroid, metabolic, and stress axes and their physiological responses. Weakly estrogenic and anti-androgenic pollutants such as bisphenol A, phthalates, phytochemicals, and the fungicide vinclozolin can lead to severe and widespread neuroendocrine disruptions in discrete brain regions, including the hippocampus, amygdala, and hypothalamus, resulting in behavioral changes in a wide range of species. Behavioral features that have been shown to be affected by one or more these chemicals include cognitive deficits, heightened anxiety or anxiety-like, sociosexual, locomotor, and appetitive behaviors. Neuroactive pharmaceuticals are now widely detected in aquatic environments and water supplies through the release of wastewater treatment plant effluents. The antidepressant fluoxetine is one such pharmaceutical neuroendocrine disruptor. Fluoxetine is a selective serotonin reuptake inhibitor that can affect multiple neuroendocrine pathways and behavioral circuits, including disruptive effects on reproduction and feeding in fish. There is growing evidence for the association between environmental contaminant exposures and diseases with strong neuroendocrine components, for example decreased fecundity, neurodegeneration, and cardiac disease. It is critical to consider the timing of exposures of neuroendocrine disruptors because embryonic stages of central nervous system development are exquisitely sensitive to adverse effects. There is also evidence for epigenetic and transgenerational neuroendocrine disrupting effects of some pollutants. We must now consider the impacts of neuroendocrine disruptors on reproduction, development, growth and behaviors, and the population consequences for evolutionary change in an increasingly contaminated world. This review examines the evidence to date that various so-called neuroendocrine disruptors can induce such effects often at environmentally-relevant concentrations.

Perfluoroalkyl acids in subarctic wild male mink (Neovison vison) in relation to age, season and geographical area

This study investigates the influence of biological and environmental factors on the concentrations of perfluoroalkyl acids (PFAAs) in a top predator; the American mink. Perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS) and perfluoroalkyl carboxylates (PFCAs) with C8-C13 perfluorinated carbon chains were analyzed in livers from wild male mink liver (n=101) from four areas in Sweden representing two inland environments (rural and highly anthropogenic, respectively) and two different coastal environments. Mean PFOS concentrations were 1250ng/g wet weight and some mink from the urban inland area had among the highest PFOS concentrations ever recorded in mink (up to 21 800ng/g wet weight). PFBS was detected in 89% of the samples, but in low concentrations (mean 0.6ng/g ww). There were significant differences in PFAA concentrations between the geographical areas (p<0.001-0.01). Age, body condition and body weight did not influence the concentrations significantly, but there was a seasonal influence on the concentrations of perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnDA) (p<0.01 and p<0.05, respectively), with lower concentrations in autumn samples than in samples taken in the winter and spring. It is thus recommended to take possible seasonal differences into account when using mink exposure data. The overall results suggest that the mink is a suitable sentinel species for assessing and monitoring environmental levels of PFAAs.

Effects of complex organohalogen contaminant mixtures on thyroid homeostasis in hooded seal (Cystophora cristata) mother-pup pairs

Many lipid-soluble and phenolic compounds present in the complex mixture of orgaohalogen contaminants (OHCs) that arctic wildlife is exposed to have the ability to interfere with the thyroid hormone (TH) system. The aim of this study was to identify compounds that might interfere with thyroid homeostasis in 14 nursing hooded seal (Cystophora cristata) mothers and their pups (1-4d old) sampled in the West Ice in March 2008. Multivariate modelling was used to assess the potential effects of measured plasma levels of OHCs on circulating TH levels of the measured free (F) and total (T) levels of triidothyrine (T3) and thyroxine (T4). Biological factors were important in all models (e.g. age and sex). In both mothers and pups, TT3:FT3 ratios were associated with α- and β-hexachlorocyclohexane (HCH), ortho-PCBs, chlordanes and DDTs. The similarities between the modelled TT3:FT3 responses to OHC levels in hooded seal mothers and pups most probably reflects similar exposure patterns, but could also indicate interconnected TH responses. There were some differences in the modelled TH responses of mothers and pups. Most importantly, the negative relationships between many OH-PCBs (particularly 3'-OH-CB138) and TT3:FT3 ratio and the positive relationships between TT4:FT4 ratios and polybrominated diphenyl ether [PBDE]-99, -100 and 4-OH-CB107 in pups, which was not found in mothers. Although statistical associations are not evidence per se of biological cause-effect relationships, the results suggest that thyroid homeostasis is affected in hooded seals, and that the inclusion of the fullest possible OHC mixture is important when assessing TH related effects in wildlife.