Brominated flame retardants in polar bears (Ursus maritimus) from Alaska, the Canadian Arctic, East Greenland, and Svalbard

Distribution and biomagnification of Hexabromocyclododecanes (HBCDs) in edible marine fish in the Beibu Gulf, China: Implication for seafood dietary risk

Hexabromocyclododecanes (HBCDs) are legacy additive brominated flame retardant. In present study, the distribution, biomagnification and potential human health risk associated with HBCDs were investigated in six edible marine fish species collected from three bays in the Beibu Gulf, China, between March and October 2021. The concentration of HBCDs ranged from 0.05 to 200 ng/g lipid weight (lw), with Scoliodon laticaudus and Trichiurus nanhaiensis having the highest and lowest concentration, respectively. The α-HBCD was dominant in most studied fish, expect for Scoliodon laticaudus. Dietary source was the primary factor for the diastereomeric profiles of HBCDs in fish. Only γ-HBCD demonstrated trophic magnification in the studied fish species. Finally, the estimated daily intake (EDI) was 0.18 ng/kg/day for adults, 0.17 ng/kg/day for teenager and children, and all corresponding margin of exposure (MOE) values were lager than 8 indicating relatively low human exposure risks from fish consumption.

Effects of temperature and relative humidity on soil-air partition coefficients of organophosphate flame retardants and polybrominated diphenyl ethers

The soil-air partition coefficients (K_SA) of polybrominated diphenyl ethers (PBDEs) and organophosphate flame retardants (OPFRs) is important for determining their fate in soil and air media. However, K_SA values of OPFRs and PBDEs are not available from the current literature, and the effects of environmental factors such as temperature and relative humidity (RH) on K_SA values are not clear. In this study, a solid-phase fugacity meter was used to measure the K_SA values of PBDEs and OPFRs at different temperatures (25, 30, 35, 40, and 45 °C) and relative humidity (RH) conditions (<3 and 100% RH), the relationships between K_SA and octanol-air partition coefficients (K_OA) for OPFRs and PBDEs were analyzed. The results showed that an increase in temperature and RH resulted in a decrease of all K_SA values for PBDEs and OPFRs. Furthermore, the effects of RH on the soil-air partitioning behavior of PBDEs were larger than that of OPFRs. In addition, a significant correlation (p < 0.0001) was observed between log K_SA and log K_OA. The experimental K_SA values of OPFRs and PBDEs were quite different from the predicted K_SA, when calculated with their K_OA values. Overall, this study provides a better understanding for predicting the behavior and fate of OPFRs and PBDEs in soil-air systems.

Update of the risk assessment of hexabromocyclododecanes (HBCDDs) in food

The European Commission asked EFSA to update its 2011 risk assessment on hexabromocyclododecanes (HBCDDs) in food. HBCDDs, predominantly mixtures of the stereoisomers α-, β- and γ-HBCDD, were widely used additive flame retardants. Concern has been raised because of the occurrence of HBCDDs in the environment, food and in humans. Main targets for toxicity are neurodevelopment, the liver, thyroid hormone homeostasis and the reproductive and immune systems. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour in mice can be considered the critical effects. Based on effects on spontaneous behaviour in mice, the Panel identified a lowest observed adverse effect level (LOAEL) of 0.9 mg/kg body weight (bw) as the Reference Point, corresponding to a body burden of 0.75 mg/kg bw. The chronic intake that would lead to the same body burden in humans was calculated to be 2.35 μg/kg bw per day. The derivation of a health-based guidance value (HBGV) was not considered appropriate. Instead, the margin of exposure (MOE) approach was applied to assess possible health concerns. Over 6,000 analytical results for HBCDDs in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary LB exposure to HBCDDs were fish meat, eggs, livestock meat and poultry. The CONTAM Panel concluded that the resulting MOE values support the conclusion that current dietary exposure to HBCDDs across European countries does not raise a health concern. An exception is breastfed infants with high milk consumption, for which the lowest MOE values may raise a health concern.

Distributions and biomagnification of polybrominated diphenyl ethers in a grassland ecosystem food chain

The concentrations, distributions, and biomagnification of polybrominated diphenyl ethers (PBDEs) in environmental and biological media in a terrestrial grass ecosystem were studied, The total PBDE concentrations in grasses were 4.00 × 10^-2 to 4.28 ng·g^-1. The total PBDE concentration in weasel muscle (23.2 ng·g^-1 l.w.) was the highest concentrations of all animal tissue samples, and the total PBDE concentration in hair from local herdsmen (22.2 ng·g^-1 l.w.) was second highest. Less-brominated PBDEs were found to be more strongly biomagnified than more-brominated PBDEs in the grassland food web. PBDEs were found to be much more strongly biomagnified in the food chains of homothermic animals than heterothermic animals. More-brominated PBDEs were not markedly biomagnified in the grassland food web. For example, BDE-153 was not biomagnified in the grassland wildlife food chain but was clearly biomagnified through the sheep, cattle, or horse hair to human hair route. The biomagnification factors and log K_ows negatively correlated for the toad-snake, lizard-snake, and mouse-weasel food chains. The ability of PBDE congeners to become enriched generally decreased as the log K_ow increased, and this decrease occurred 100-1000 times more strongly for homothermic animals than heterothermic animals.

Adipose Tissue Transcriptome Is Related to Pollutant Exposure in Polar Bear Mother-Cub Pairs from Svalbard, Norway

Being at the food chain apex, polar bears (Ursus maritimus) are highly contaminated with persistent organic pollutants (POPs). Females transfer POPs to their offspring through gestation and lactation; therefore, young cubs present higher POPs concentrations than their mothers. Recent studies suggest that POPs affect the lipid metabolism in female polar bears; however, the mechanisms and impact on their offspring remain unknown. Here, we hypothesized that exposure to POPs differentially alters genome-wide gene transcription in the adipose tissue from mother polar bears and their cubs, highlighting molecular differences in response between adults and young. Adipose tissue biopsies were collected from 13 adult female polar bears and their twin cubs in Svalbard, Norway, in April 2011, 2012, and 2013. Total RNA extracted from biopsies was subjected to next-generation RNA sequencing. Plasma concentrations of summed polychlorinated biphenyls, organochlorine pesticides, and polybrominated diphenyl ethers in mothers ranged from 897 to 13620 ng/g wet weight and were associated with altered adipose tissue gene expression in both mothers and cubs. In mothers, 2502 and 2586 genes in total were positively and negatively, respectively, correlated to POP exposure, whereas in cubs, 2585 positively and 1690 negatively genes. Between mothers and cubs, 743 positively and negatively genes overlapped between mothers and cubs suggesting partially shared molecular responses to ΣPOPs. ΣPOP-associated genes were involved in numerous metabolic pathways in mothers and cubs, indicating that POP exposure alters the energy metabolism, which, in turn, may be linked to metabolic dysfunction.

Interspecies comparison of the residue levels and profiles of persistent organic pollutants in terrestrial top predators

Serum samples from three species of living terrestrial top predators were analysed for six groups of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane compounds (CHLs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and polybrominated diphenyl ethers (PBDEs). The study included three carnivore species: lion (Panthera leo), hyena (Hyena brunnea) and cheetah (Acinonyx jubatus). All samples were collected from healthy living animals between 2004 and 2005. Most of the samples (wild lions (n = 50) and hyenas (n = 11)) were collected from various locations within the Kruger National Park and Addo National Park (South Africa), while captive lions (n = 6) and cheetahs (n = 3) were collected from the Antwerp Zoo (Belgium). In general, relatively low levels of POPs were found in the studied species, varying widely within species and locations. Median concentrations of POPs were higher in captive lions (PCBs: 505 pg/mL; DDTs: 270 pg/mL; HCHs: 72 pg/mL; HCB: 34 pg/mL; CHLs: 24 pg/mL; PBDEs: 8 pg/mL) compared to wild lions (DDTs: 274 pg/mL; HCHs: 44 pg/mL; CHLs: 7.9 pg/mL; PCBs: 2.1 pg/mL; HCB: < LOQ; PBDEs: < LOQ). In the wild animals, POPs accumulated in the following order: DDTs > HCHs > CHLs > HCB > PCBs > PBDEs, while in the captive animals, the order was: PCBs > DDTs > CHLs > HCHs > HCB > PBDEs, suggesting differences in the diet of these animals. Furthermore, wild hyena contained significantly higher (p < 0.05) median levels of POPs compared to wild lions, possibly reflecting differences in metabolic capacity and/or feeding habits, together with an uneven distribution of POPs in the area where the animals lived. No previous data are available to compare for similar terrestrial top predators, such as lion, hyena and cheetah. To our knowledge, this is first study on POPs in these three species. The low POP levels found in this study were several orders of magnitude lower than those for other carnivore species, such as polar bears, grizzly bears, brown bears and wolves worldwide. The present study has revealed the need for expanding research and monitoring on occurrence, levels and disposition of POPs in the top predators of the terrestrial environment.

Bioaccumulation and biomagnification of PBDEs in a terrestrial food chain at an urban landfill

Biota samples from the Vancouver municipal landfill located in Delta, BC, Canada, have some of the highest polybrominated diphenyl ether (PBDE) levels reported from North America. We followed a population of European starlings (Sturnus vulgaris) breeding in a remediated area in the landfill to identify exposure routes and bioaccumulation of PBDEs in a simple terrestrial food chain. This population was compared to a reference farm site located 40 km east in Glen Valley. We analyzed samples of European starling eggs and nestling livers as well as invertebrate prey species consumed by starlings for PBDE concentrations. We also collected soil samples from starling foraging areas. All samples from the Delta landfill had higher PBDE congener concentrations compared to the Glen Valley reference site and were dominated by BDE-99 and BDE-47. Stable nitrogen (δ N¹⁵) and carbon (δ C¹³) isotope analysis of starling blood samples and provisioned invertebrates revealed that stable δ_C¹³ signatures differed between the sites indicating that the diet of starlings in the Delta landfill included a component of human refuse. Biota-soil accumulation factors (BSAFs) > 1 demonstrated that PBDEs were bioaccumulating in soil invertebrates, particularly earthworms, which were readily accessible to foraging starlings in the landfill. Biomagnification factors (BMFs) calculated from foraged food items and starling egg and liver samples were >1, indicating that a diet of soil invertebrates and refuse contributed substantially to the PBDE exposure of local starlings.

Environmental contaminants in coastal populations: Comparisons with the National Health and Nutrition Examination Survey (NHANES) and resident dolphins

BACKGROUND

People living in coastal communities are at risk for exposure to environmental hazards, including legacy chemicals. We can use databases such as NHANES to assess whether contaminants in coastal communities are present in higher levels than in the United States overall. We can use information from studies of local animal populations to assess which of these contaminants could have been transferred to people from their shared environment.

OBJECTIVE

Our objectives were to examine the POP profiles in human populations in areas where there are published POP profiles in resident dolphins and to compare our results with data from NHANES and the dolphin studies.

METHODS

We identified three areas where POPs have been analyzed in local resident dolphin populations (total N =73). We identified human communities in the same areas, and asked 27 eligible adults to read and sign a consent form, complete a questionnaire about demographics and seafood consumption, provide nine 10-mL blood samples, and provide one sample of seafood (N = 33). Blood and seafood were analyzed for a suite of POPs similar to those analyzed in published dolphin population studies. We compared the results from human blood analyses with NHANES and with data from the published reports of dolphin studies.

RESULTS

Levels and proportions of specific POPs found in people and animals reflect POPs found in the local environment. Compared with the nationally representative data reported in NHANES, the levels of many POPs found in high levels in dolphins were also higher in the corresponding human communities.

CONCLUSIONS

Contaminants measured in marine animals, such as dolphins, can be used to identify the types and relative levels of environmental contaminants expected to occur in people sharing the same environment. Likewise, contaminants measured in coastal human populations can provide insight into which contaminants may be found in nearby animal populations.

Trends of persistent organic pollutants in ringed seals (Phoca hispida) from the Canadian Arctic

Ringed seals (Phoca hispida) have been used as bioindicator species of environmental contamination in Canada since the 1970s. In the present study, seals were harvested during subsistence hunts in four regions of the Canadian Arctic: Beaufort Sea, Arctic Archipelago, Hudson Bay, and coastal Labrador. An extensive suite of persistent organic pollutants (POPs) was determined in seal blubber collected for multiple years between 1972 and 2016. Results from this long-term study indicate geographical differences in the contaminant concentrations in seals and the significant general decrease of most POPs, including polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and related compounds, chlordanes (CHL), and hexachlorocyclohexanes (HCH) over time in ringed seals. The highest decrease rates (up to -9.1%/year for α-HCH) were found in seals from the Hudson Bay region where all chemicals investigated have significantly decreased since 1986. Significant increases in concentrations of hexachlorobenzene (HCB) in seals from Labrador and β-HCH in Sachs Harbour, NT and Arctic Archipelago were observed. Site-specific and contaminant-specific associations between climate pattern (i.e., Arctic Oscillation, North Atlantic Oscillation, and Pacific/North American pattern) and mean ice-coverage (total, first-year ice, and old-ice) were found at sites with the longest time trend data (i.e., Arviat, Sachs Harbour/Ulukhaktok and Resolute Bay). Overall, results suggest that North American and international regulations have led to the long-term reduction of most POPs in Canadian Arctic ringed seals by reducing emissions from primary sources. However, other sources of legacy compounds (e.g., environmental reservoirs) as well changes in food web composition and structure in relation to climate changes could also be influencing the very slow rates of decline, or stable levels, of contaminants found in seals at some sites. Further work is warranted to discern between co-variation of climate changes and contaminant concentrations and cause-and-effect relationships.

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.

Climatic Influence on Temporal Trends of Polychlorinated Biphenyls and Organochlorine Pesticides in Landlocked Char from Lakes in the Canadian High Arctic

Temporal trends and climate related parameters affecting the fate of legacy persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were examined in landlocked Arctic char from four lakes in the Canadian Arctic. Among biological parameters, lipid content was a key factor explaining the concentration of most POPs in Arctic char. Legacy PCBs and OCPs generally showed declining trends of concentrations in Arctic char, consistent with past restriction on uses and emissions of POPs. However, increases in lake primary productivity (measured as chlorophyll a) exerted a dilution effect on POPs concentrations in Arctic char. Concentrations of POPs in char from the last two decades were positively correlated with interannual variations of the North Atlantic Oscillation (NAO). Higher concentrations of POPs in Arctic char were observed in 3 of the 4 lakes during positive NAO phases. This, together with increasing local Arctic temperatures, could lead to increases on POPs concentrations in char from remote Arctic Lakes in future decades. Also, if there are nearby secondary sources as may be the case for Resolute Lake, located near an airport where increasing levels were found for hexachlorobenzene and toxaphene, probably due to the mobilization from secondary sources in soils.

Exposure to polybrominated diphenyl ethers (PBDEs) and child behavior: Current findings and future directions

Polybrominated diphenyl ethers (PBDEs) are recognized neurotoxicants, but the extent to which PBDEs influence various domains of behavior in children is not fully understood. As such, we reviewed epidemiologic studies published to date to provide an overview of the current state of knowledge on PBDEs' potential role in behavioral development. We identified 19 epidemiologic studies reporting on associations of prenatal and childhood concentrations of PBDEs with behaviors assessed in children from 1 to 12years, including executive function, attention, externalizing and internalizing behaviors, adaptive skills, and social behaviors/Autism Spectrum Disorder (ASD). While the mechanisms of PBDE neurotoxicity in humans are still not clearly elucidated, findings from this review indicate that PBDE exposure during fetal development is associated with impairments in executive function and poorer attentional control in children. Results from large prospective cohorts demonstrate that prenatal and postnatal PBDE exposure adversely impacts externalizing behavior (e.g., hyperactivity and conduct problems). Additional studies are needed to determine whether PBDEs are associated with internalizing problems, adaptive skills, and social behaviors/ASD in children. Future studies will help better understand the potential neurotoxic effects of PBDE exposures during adolescence, possible sex-dependent effects, and the impact of exposure to BDE-209 and alternative flame retardants. Future studies should also examine chemical mixtures to capture real-world exposures when examining PBDEs and their impact on various behavioral domains in the context of multiple chemical exposures.

Legacy and new halogenated persistent organic pollutants in polar bears from a contamination hotspot in the Arctic, Hudson Bay Canada

A large and complex suite of 295 legacy and new halogenated persistent organic pollutants (POPs) were investigated in fat or liver tissue samples of polar bears collected in 2013-2014 from Southern (SHB) and Western (WHB) subpopulations of the Canadian Arctic contaminants hotspot of Hudson Bay. A total of 210 POPs were detected and/or quantifiable with some frequency in all fat or liver samples. POP profile and concentration differences were investigated both within (e.g. age and sex) and between the two subpopulations. Two time-point comparisons were made relative to POPs reported for Hudson Bay polar bears harvested in 2007-2008. ΣPolychlorinated biphenyl (PCB) concentrations at both time points were the most concentrated of the POP groups, and were spatially uniform with no detectable influence of sex or age, as were concentrations of the dominant congener CB153. ΣChlordanes (ΣCHLs, 74-79% oxychlordane) and the Σperfluoroalkyl substances (ΣPFASs, ≈60% perfluorooctane sulfonate (PFOS)) had the second greatest POP group concentrations in SHB and WHB respectively, with ΣPFASs and ΣCHLs being significantly influenced by age and/or sex. ΣCHLs were spatially uniform but ΣPFASs were greater in the SHB bears, as were e.g. some flame retardants, due to e.g. local contamination and/or changes in bear behavior and diet. Endosulfans and hexabromocyclododecane were detectable in samples from 2007-2008 but not from 2013-2014, which is consistent with their global POP regulations. ΣPolychlorinated naphthalenes (ΣPCNs) were consistently detected at relatively high concentrations compared to other arctic wildlife, however these concentrations were low relative to legacy POPs. ΣShort-chain chlorinated paraffins (ΣSCCPs) were major contributors to the overall POPs burden with concentrations comparable to other legacy POPs, though there was no significant difference between or within subpopulations for PCNs or SCCPs. Except for octachlorostyrene, POPs concentrations were generally lower in female and male bears from SHB in 2013-2014 relative to 2007-2008, however those of WHB males were greater over the same timeframe for almost all POPs.

A veterinary perspective on One Health in the Arctic

Exposure to long-range transported industrial chemicals, climate change and diseases is posing a risk to the overall health and populations of Arctic wildlife. Since local communities are relying on the same marine food web as marine mammals in the Arctic, it requires a One Health approach to understand the holistic ecosystem health including that of humans. Here we collect and identify gaps in the current knowledge of health in the Arctic and present the veterinary perspective of One Health and ecosystem dynamics. The review shows that exposure to persistent organic pollutants (POPs) is having multiple organ-system effects across taxa, including impacts on neuroendocrine disruption, immune suppression and decreased bone density among others. Furthermore, the warming Arctic climate is suspected to influence abiotic and biotic long-range transport and exposure pathways of contaminants to the Arctic resulting in increases in POP exposure of both wildlife and human populations. Exposure to vector-borne diseases and zoonoses may increase as well through range expansion and introduction of invasive species. It will be important in the future to investigate the effects of these multiple stressors on wildlife and local people to better predict the individual-level health risks. It is within this framework that One Health approaches offer promising opportunities to survey and pinpoint environmental changes that have effects on wildlife and human health.

Multiple-stressor effects in an apex predator: combined influence of pollutants and sea ice decline on lipid metabolism in polar bears

There is growing evidence from experimental and human epidemiological studies that many pollutants can disrupt lipid metabolism. In Arctic wildlife, the occurrence of such compounds could have serious consequences for seasonal feeders. We set out to study whether organohalogenated compounds (OHCs) could cause disruption of energy metabolism in female polar bears (Ursus maritimus) from Svalbard, Norway (n = 112). We analyzed biomarkers of energy metabolism including the abundance profiles of nine lipid-related genes, fatty acid (FA) synthesis and elongation indices in adipose tissue, and concentrations of lipid-related variables in plasma (cholesterol, high-density lipoprotein, triglycerides). Furthermore, the plasma metabolome and lipidome were characterized by low molecular weight metabolites and lipid fingerprinting, respectively. Polychlorinated biphenyls, chlordanes, brominated diphenyl ethers and perfluoroalkyl substances were significantly related to biomarkers involved in lipid accumulation, FA metabolism, insulin utilization, and cholesterol homeostasis. Moreover, the effects of pollutants were measurable at the metabolome and lipidome levels. Our results indicate that several OHCs affect lipid biosynthesis and catabolism in female polar bears. Furthermore, these effects were more pronounced when combined with reduced sea ice extent and thickness, suggesting that climate-driven sea ice decline and OHCs have synergistic negative effects on polar bears.

Potentiation of ecological factors on the disruption of thyroid hormones by organo-halogenated contaminants in female polar bears (Ursus maritimus) from the Barents Sea

As apex predators, polar bears (Ursus maritimus) are among the most heavily polluted organisms in the Arctic. In addition to this anthropogenic stressor, climate warming has been shown to negatively affect their body condition, reproductive output and survival. Among potential underlying physiological mechanisms, thyroid hormones (THs), which control thermoregulation, metabolism and reproduction, can be affected by a variety of both natural and anthropogenic factors. While THs have been extensively used as proxies for pollution exposure in mammals, including polar bears, there is a lack of knowledge of their natural variations. In this context, we examined seasonal variations in body condition and circulating TH concentrations in free-ranging female polar bears. Females with variable reproductive status (i.e., solitary, with cubs of the year or with yearlings) were sampled from locations with contrasted sea ice conditions. Furthermore, we studied THs in relation to levels of organo-halogenated contaminants. As predicted, solitary females were in better condition than females caring for offspring, especially in spring. In addition, TH levels were lower in autumn compared to spring, although this seasonal effect was mainly observed in solitary females. Finally, the negative relationships between organochlorine and perfluoroalkyl substances and some THs suggest a possible alteration of homeostasis of THs. Since the latter relationships were only observed during spring, we emphasize the importance of considering the ecological factors when using THs as proxies for pollution exposure. Yet, the combined effects of natural and anthropogenic stressors on THs might impair the ability of polar bears to adapt to ongoing climate changes.

Spatial and temporal trends of alternative flame retardants and polybrominated diphenyl ethers in ringed seals (Phoca hispida) across the Canadian Arctic

Concentrations of alternative flame retardants and polybrominated diphenyl ethers (PBDEs) were analyzed in ringed seal (Phoca hispida) blubber collected across the Canadian Arctic during subsistence hunts between 1998 and 2013. More than 80% of sampled animals were females and juvenile males. The highest mean ΣPBDE concentrations (sum of 13 congeners) were found in seals from Nain (Nunatsiavut) as well as Inukjuaq and Arviat (Hudson Bay) and the lowest mean levels were found in seals from Lancaster Sound. BDE-47 and -99 were the predominant PBDE congeners quantified in ringed seals. The most frequently detected non-PBDE flame retardants were polybrominated biphenyl 101 (BB-101, 57% of samples analyzed for this chemical), hexabromocyclododecane (HBCDD; 38%), hexabromobenzene (HBB, 30%), and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTeBB, 23%). The relative trophic position of seals, estimated using stable isotopes, did not vary over time and did not influence flame retardant blubber concentrations. The relative carbon source increased over time at Arviat and Resolute Bay and weak relationships were observed with ΣPBDEs in blubber of seals. ΣPBDEs increased significantly from 1998 to 2008 in ringed seals from East Baffin and subsequently decreased in recent years. PBDE levels at other sites fluctuated slightly over time. HBCDD concentrations increased at several sites over the past decade. The presence of flame retardants in ringed seals suggests their persistence and their continuous inputs in the Canadian Arctic environment. Monitoring and research on the effects of these contaminants in seals are warranted given the importance of this species in Arctic marine food webs and for local communities.

Circumpolar contaminant concentrations in polar bears (Ursus maritimus) and potential population-level effects

Polar bears (Ursus maritimus) currently receive much attention in the context of global climate change. However, there are other stressors that might threaten the viability of polar bear populations as well, such as exposure to anthropogenic pollutants. Lipophilic organic compounds bio-accumulate and bio-magnify in the food chain, leading to high concentrations at the level of top-predators. In Arctic wildlife, including the polar bear, various adverse health effects have been related to internal concentrations of commercially used anthropogenic chemicals like PCB and DDT. The extent to which these individual health effects are associated to population-level effects is, however, unknown. In this study we assembled data on adipose tissue concentrations of ∑PCB, ∑DDT, dieldrin and ∑PBDE in individual polar bears from peer-reviewed scientific literature. Data were available for 14 out of the 19 subpopulations. We found that internal concentrations of these contaminants exceed threshold values for adverse individual health effects in several subpopulations. In an exploratory regression analysis we identified a clear negative correlation between polar bear population density and sub-population specific contaminant concentrations in adipose tissue. The results suggest that adverse health effects of contaminants in individual polar bears may scale up to population-level consequences. Our study highlights the need to consider contaminant exposure along with other threats in polar bear population viability analyses.

Persistent organic pollutants in the Antarctic coastal environment and their bioaccumulation in penguins

Persistent organic pollutants (POPs), including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), polybrominated biphenyls (PBBs), and polybrominated diphenyl ethers (PBDEs), have been identified in penguins, lichens, soils, and ornithogenic soils in the Antarctic coastal environment in this study. To the best of our knowledge, no previous study has reported PBDD/F and PBB data from Antarctica. The POP mass contents in penguins were in the following order: PCBs >> PBDEs >> PCDD/Fs; PCBs were the dominant pollutants (6310-144,000 pg/g-lipid), with World Health Organization toxic equivalency values being 2-14 times higher than those of PCDD/Fs. Long-range atmospheric transport is the most primary route by which POPs travel to Antarctica; however, local sources, such as research activities and penguin colonies, also influence POP distribution in the local Antarctic environment. In penguins, the biomagnification factor (BMF) of PCBs was 61.3-3760, considerably higher than that for other POPs. According to BMF data in Adélie penguins, hydrophobic PBDE congeners were more biomagnified at log Kow > 6, and levels decreased at log Kow > 7.5 because larger molecular sizes inhibited transfer across cell membranes.

Year-Round Monitoring of Contaminants in Neal and Rogers Creeks, Hood River Basin, Oregon, 2011-12, and Assessment of Risks to Salmonids

Pesticide presence in streams is a potential threat to Endangered Species Act listed salmonids in the Hood River basin, Oregon, a primarily forested and agricultural basin. Two types of passive samplers, polar organic chemical integrative samplers (POCIS) and semipermeable membrane devices (SPMDs), were simultaneously deployed at four sites in the basin during Mar. 2011-Mar. 2012 to measure the presence of pesticides, polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs). The year-round use of passive samplers is a novel approach and offers several new insights. Currently used pesticides and legacy contaminants, including many chlorinated pesticides and PBDEs, were present throughout the year in the basin's streams. PCBs were not detected. Time-weighted average water concentrations for the 2-month deployment periods were estimated from concentrations of chemicals measured in the passive samplers. Currently used pesticide concentrations peaked during spring and were detected beyond their seasons of expected use. Summed concentrations of legacy contaminants in Neal Creek were highest during July-Sept., the period with the lowest streamflows. Endosulfan was the only pesticide detected in passive samplers at concentrations exceeding Oregon or U.S. Environmental Protection Agency water-quality thresholds. A Sensitive Pesticide Toxicity Index (SPTI) was used to estimate the relative acute potential toxicity among sample mixtures. The acute potential toxicity of the detected mixtures was likely greater for invertebrates than for fish and for all samples in Neal Creek compared to Rogers Creek, but the indices appear to be low overall (<0.1). Endosulfans and pyrethroid insecticides were the largest contributors to the SPTIs for both sites. SPTIs of some discrete (grab) samples from the basin that were used for comparison exceeded 0.1 when some insecticides (azinphos methyl, chlorpyrifos, malathion) were detected at concentrations near or exceeding acute water-quality thresholds. Early life stages and adults of several sensitive fish species, including salmonids, are present in surface waters of the basin throughout the year, including during periods of peak estimated potential toxicity. Based on these data, direct toxicity to salmonids from in-stream pesticide exposure is unlikely, but indirect impacts (reduced fitness due to cumulative exposures or negative impacts to invertebrate prey populations) are unknown.

Climate Change in the North American Arctic: A One Health Perspective

Climate change is expected to increase the prevalence of acute and chronic diseases among human and animal populations within the Arctic and subarctic latitudes of North America. Warmer temperatures are expected to increase disease risks from food-borne pathogens, water-borne diseases, and vector-borne zoonoses in human and animal populations of Arctic landscapes. Existing high levels of mercury and persistent organic pollutant chemicals circulating within terrestrial and aquatic ecosystems in Arctic latitudes are a major concern for the reproductive health of humans and other mammals, and climate warming will accelerate the mobilization and biological amplification of toxic environmental contaminants. The adverse health impacts of Arctic warming will be especially important for wildlife populations and indigenous peoples dependent upon subsistence food resources from wild plants and animals. Additional research is needed to identify and monitor changes in the prevalence of zoonotic pathogens in humans, domestic dogs, and wildlife species of critical subsistence, cultural, and economic importance to Arctic peoples. The long-term effects of climate warming in the Arctic cannot be adequately predicted or mitigated without a comprehensive understanding of the interactive and synergistic effects between environmental contaminants and pathogens in the health of wildlife and human communities in Arctic ecosystems. The complexity and magnitude of the documented impacts of climate change on Arctic ecosystems, and the intimacy of connections between their human and wildlife communities, makes this region an appropriate area for development of One Health approaches to identify and mitigate the effects of climate warming at the community, ecosystem, and landscape scales.

Polyhalogenated compounds (PCBs, chlordanes, HCB and BFRs) in four polar bears (Ursus maritimus) that swam malnourished from East Greenland to Iceland

Levels of organohalogen compounds (PCBs, chlordane, PBB 153, PBDEs, HCB) were determined in adipose tissue, liver, kidney and muscle of four polar bears which swam and/or drifted to Iceland in extremely malnourished condition. Since the colonization in the 9th century polar bears have been repeatedly observed in Iceland. However, in recent years three of the animals have clearly left their natural habitat in poor condition in May or June, i.e. at the end of the major feeding season. The fourth bear is believed to have drifted with melting ice to North-Eastern Iceland in mid-winter. The concentrations of the POPs were within the range or higher than the typical concentrations measured in polar bears from the East Greenland population. In addition to the targeted compounds, we tentatively detected Dechlorane 602 and its potential hydrodechlorinated Cl11-metabolite in all samples. Moreover, a polychlorinated compound which partly co-eluted with PCB 209 was detected in all liver samples but not in adipose tissue, kidney or muscle. The mass spectrum of the potential metabolite did not allow determining its structure. Polar bears are good swimmers and can reach Iceland from the ice edge of East Greenland within a few days. Potential reasons for the swims are briefly discussed.

Physiologically-based pharmacokinetic modelling of immune, reproductive and carcinogenic effects from contaminant exposure in polar bears (Ursus maritimus) across the Arctic

Polar bears (Ursus maritimus) consume large quantities of seal blubber and other high trophic marine mammals and consequently have some of the highest tissue concentrations of organohalogen contaminants (OHCs) among Arctic biota. In the present paper we carried out a risk quotient (RQ) evaluation on OHC-exposed polar bears harvested from 1999 to 2008 and from 11 circumpolar subpopulations spanning from Alaska to Svalbard in order to evaluate the risk of OHC-mediated reproductive effects (embryotoxicity, teratogenicity), immunotoxicity and carcinogenicity (genotoxicity). This RQ evaluation was based on the Critical Body Residue (CBR) concept and a Physiologically-Based Pharmacokinetic Modelling (PBPK) approach using OHC concentrations measured in polar bear adipose or liver tissue. The range of OHC concentrations within polar bear populations were as follows for adipose, sum polychlorinated biphenyls ∑PCBs (1797-10,537 ng/g lw), sum methylsulphone-PCB ∑MeSO2-PCBs (110-672 ng/g lw), sum chlordanes ∑CHLs (765-3477 ng/g lw), α-hexachlorocyclohexane α-HCH (8.5-91.3 ng/g lw), β-hexachlorocyclohexane β-HCH (65.5-542 ng/g lw), sum chlorbenzenes ∑ClBzs (145-304 ng/g lw), dichlorodiphenyltrichloroethane ∑DDTs (31.5-206 ng/g lw), dieldrin (69-249 ng/g lw), polybrominated diphenyl ethers ∑PBDEs (4.6-78.4 ng/g lw). For liver, the perfluorooctanesulfonic acid (PFOS) concentrations ranged from 231-2792 ng/g ww. The total additive RQ from all OHCs ranged from 4.3 in Alaska to 28.6 in East Greenland bears for effects on reproduction, immune health and carcinogenicity, highlighting the important result that the toxic effect threshold (i.e. RQ>1) was exceeded for all polar bear populations assessed. PCBs were the main contributors for all three effect categories, contributing from 70.6% to 94.3% of the total risk and a RQ between 3.8-22.5. ∑MeSO2-PCBs were the second highest effect contributor for reproductive and immunological effects (0.17<RQ<1.4), whereas PFOS was the second highest effect contributor for carcinogenic (genotoxic) effects (0.35<RQ<2.5). The results from this study corroborate and lend further support to previous assessments of the possible adverse health effects of exposure to known and measured OHCs in polar bears. We therefore suggest that Critical Daily Doses (CDD) should be investigated in "ex vivo" dose-response studies on polar bears to replace laboratory studies on rats (Rattus rattus) to reveal whether high RQs are maintained.

Levels and temporal trends of persistent organic pollutants (POPs) in arctic foxes (Vulpes lagopus) from Svalbard in relation to dietary habits and food availability

Temporal trends of persistent organic pollutants (POPs) in arctic foxes (Vulpes lagopus) from Svalbard, Norway, were investigated in relation to feeding habits and seasonal food availability. Arctic foxes from Svalbard forage in both marine and terrestrial ecosystems and the availability of their food items are impacted by climatic variability. Concentrations of polychlorinated biphenyls (PCBs), organochlorinated pesticides (OCPs) and brominated flame retardants (polybrominated diphenyl ethers [PBDEs] and hexabromocyclododecane [HBCDD]) were analyzed in the liver of 141 arctic foxes collected between 1997 and 2013. Stable carbon isotope values (δ13C) were used as a proxy for feeding on marine versus terrestrial prey. The annual number of recovered reindeer carcasses and sea ice cover were used as proxies for climate influenced food availability (reindeers, seals). Linear models revealed that concentrations of PCBs, chlordanes, p,p'-DDE, mirex and PBDEs decreased 4-11% per year, while no trends were observed for hexachlorobenzene (HCB) or β-hexachlorocyclohexane (β-HCH). Positive relationships between POP concentrations and δ13C indicate that concentrations of all compounds increase with increasing marine dietary input. Increasing reindeer mortality was related to lower HCB concentrations in the foxes based on the linear models. This suggests that concentrations of HCB in arctic foxes may be influenced by high mortality levels of Svalbard reindeer. Further, β-HCH concentrations showed a positive association with sea ice cover. These results in addition to the strong effect of δ13C on all POP concentrations suggest that climate-related changes in arctic fox diet are likely to influence contaminant concentrations in arctic foxes from Svalbard.

Changes of polybrominated diphenyl ether concentrations in ducks with background exposure level and time

To reveal what degree bioaccumulation of polybrominated diphenyl ethers (PBDEs) depends on exposure time and other factors, we conducted a semi-field experiment for a year (June 2008-June 2009) in a village in an e-waste recycling site in Taizhou, China. Approximately one hundred of juvenile ducks (Anas domestica Linnaeus) were entrusted to a villager. The ducks lived and forged in a PBDE-polluted pond from the late March to the end of November. Fish and mudsnails that were heavily polluted by PBDEs were main food. In cold days (from December to the middle March), the ducks lived in the villager' house, and mainly fed on paddy, which contained lower concentrations of PBDEs than fish and mudsnails. The female ducks were sampled for PBDE analysis every three months. We found that the ∑PBDE concentrations in duck liver, muscle, lung and brain fluctuated greatly with the changes of exposure levels that were determined by the environment and diets, but the ∑PBDE concentrations in fat tissue increased successively with time. Congener analysis demonstrated that the successive increase in the ∑PBDE concentrations with time in fat tissue was due to the successive increase in BDE-209, -183 and -153 concentrations, with large fluctuations of low brominated congeners. The results show that PBDE concentrations in liver, muscle, lung and brain tissues heavily depends on exposure levels rather than exposure time. In fat tissue, by contrast, PBDE concentrations (mainly high brominated congeners) slightly depends on exposure levels but heavily depend on time relative to other tissues, implying that high brominated congeners seem to have longer half-lives than low brominated congeners in fat tissue.

The distribution and biomagnification of higher brominated BDEs in terrestrial organisms affected by a typical e-waste burning site in South China

Soil, vegetation, and several terrestrial species including turtledove, chicken, goose, grasshopper, dragonfly, butterfly and ant, were collected from an area surrounding a typical e-waste burning site in South China. The samples were examined to investigate the levels, congener profiles, and biomagnification extent of polybrominated diphenyl ethers (PBDEs) that may be present in the environment as a result of the e-waste, which was processed in a crude recycling style. Elevated levels of Σ(21)PBDEs were found in the biota (101–4725 ng g(−1) lipid weight (lw)), vegetation leaf (82.9–319 ng g(−1) dry weight (dw)) and soil samples (5.2–22 110 ng g(−1) dw), indicating that PBDE contamination in the samples collected from the e-waste burning site may pose risks to the local terrestrial ecosystem and local populations. Higher BDE congeners, especially deca-BDE (BDE-209) were the dominant homologs in organisms and nonbiological matrices, followed by nona-BDE and octa-BDE. Biomagnification factors (BMFs) were calculated as the ratio of the lipid-normalized concentration in the predator to that in the prey. The highest BMF (3.4) was determined for BDE-153 in the grasshopper/turtledove food chain. Other higher brominated congeners, such as BDE-202, -203, -154, -183 and -209, were also biomagnified in the terrestrial food chain with BMFs of 1.7–3.3. BDE-47, -100, and -99 were not biomagnified in the examined food chains (BMFs < 1), which suggests that bioaccumulation and biotransformation of PBDEs in terrestrial ecosystems could be distinguished from those in aquatic ecosystems.

Organotropism of persistent organic pollutants and heavy metals in the Greenland shark Somniosus microcephalus in NE Greenland

The Greenland shark Somniosus microcephalus is an opportunistic feeder, a top predator, and a very long-lived species. The brain, liver, red and white muscle, gonads, fat, skin, pancreas, and spleen of Greenland sharks from NE Greenland fjords were analysed for PCBs, PCDDs/DFs, PBDEs; DDT isomers; HCH isomers; dieldrin; endrin; HCB; Cd, Hg, Pb, and Se. PCBs (2.01-103 ng/g wet wt) and PBDEs (7.9-3050 pg/g wet wt) were detected in most of the samples. PCDDs/DFs showed high values when detected. DDTs, HCB and HCHs were only detected in some tissues. The ΣTEQ was 5.76 pg/g in muscle. Cadmium mainly accumulated in the pancreas and liver (19.6 and 10.7 mg/kg dry wt, respectively); mercury in red muscle (4.10-6.91 mg/kg dry wt); selenium in the pancreas (3.57 mg/kg dry wt) and spleen (1.95 mg/kg dry wt); lead in the skin (0.358 mg/kgd ry wt). The selenium-mercury ratio in the liver was also evaluated.

Bioaccumulation of persistent organic pollutants in stranded cetaceans from Taiwan coastal waters

This study focuses on analyzing PBDEs in the liver, muscle, and blubber tissues of stranded dolphins (Stenella attenuate) on the Taiwan coast to determine and compare the PBDE levels and distributions among tissue types. Total concentrations of 19 PBDEs (ΣPBDE) in male dolphins (9.97 to 436ng/g fat) were significantly higher than in female animals (2.73 to 89.5ng/g fat), implying gender variation in bioaccumulation and the possibility of generation transfer from mother to fetus during pregnancy. The levels of contamination varied among tissue type; contamination was higher in blubber than that in muscle or liver, suggesting a possible transformation and redistribution of these compounds in body burden. Aside from gender and tissue type, ΣPBDE concentrations also significantly correlated with body length, an indicator of dolphin age. PCA analysis results showed no significant difference in PBDE congener pattern distributions in blubber tissues, indicating that blubber may be the final storage of contaminants in cetaceans, and that bioaccumulation of PBDEs may be dependent on chemical properties. BDE-154 and BDE-47 were the predominant PBDE congeners in stranded dolphins, and their correlation with body length suggests the significant metabolic depletion of BDE-154 in this species and possible exposure to both penta-BDE and octa-BDE mixtures.

Altered vitamin D status in liver tissue and blood plasma from Greenland sledge dogs (Canis familiaris) dietary exposed to organohalogen contaminated minke whale (Balaenoptera acuterostrata) blubber

This study compared vitamin D3 (vitD3) and 25-OH vitamin D3 (25OHD3) status in Greenland sledge dogs (Canis familiaris) given either minke whale (Balaenoptera acuterostrata) blubber high in organohalogen contaminants (OHCs) or clean porcine (Suis scrofa) fat for up to 636 days. A group of six exposed and six control sister bitches (maternal generation) and their three exposed and four control pups, respectively, were daily fed 112g whale blubber (193µg ∑PCB/day) or porcine fat (0.17µg ∑PCB/day). Mean level of ∑PCB in adipose tissue of exposed bitches and their pups was 3106 and 2670ng/g lw, respectively, which was significantly higher than the mean concentration of 53ng/g lw for all controls (p<0.001). The vitamin analyses showed that 25OHD3 in liver of maternal exposed bitches were significantly lower than in controls (p=0.004) while vitD3 was significantly highest in liver of exposed pups (p<0.003). Regarding blood plasma concentrations, exposed F generation pups had significantly higher concentrations of 25OHD3 than controls (p=0.009). Correlation analyses showed that blood 25OHD3 decreased significantly with increased adipose tissue concentrations of ∑PCB in exposed dogs (R(2)=0.64, p=0.005) and a similar trend was found for liver 25OHD3 (R(2)=0.32, p=0.08). The results indicate that the homeostasis and metabolism of vitamin D compounds may respond differently to the dietary composition of fatty acids and OHC exposure. It is unknown if the lower level of 25OHD3 in the liver of exposed dogs would have any negative effects on immunity and reproduction and more focus should be conducted on this compound in Arctic wildlife.

Partitioning of polybrominated diphenyl ethers to dissolved organic matter isolated from Arctic surface waters

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardant that is distally transported to the Arctic. Little is known about the fate of PBDEs in Arctic surface waters, especially in the presence of dissolved organic matter (DOM). DOM has been shown to interact with hydrophobic organic contaminants and can alter their mobility, bioavailability, and degradation in the environment. In this study, the partitioning of six PBDE congeners between Arctic DOM (isolated via solid phase extraction) and water was measured using the aqueous solubility enhancement method. Measured dissolved organic carbon (DOC)-water partition coefficient (KDOC) values were nearly an order of magnitude lower than previously reported values for the same PBDE congeners in soil or commercial organic matter, ranging from 10(3.97) to 10(5.16) L kg(-1) of organic carbon. Measured results compared favorably with values calculated using polyparameter linear free energy models for Suwannee River fulvic acid. Log KDOC values increased with increasing PBDE hydrophobicity. Slightly lower than expected values were observed for the highest brominated congeners, which we attribute to steric hindrance. This study is the first to comprehensively measure KDOC values for a range of PBDE congeners with DOM isolated from Arctic surface waters.

In vitro exposure of DE-71, a penta-PBDE mixture, on immune endpoints in bottlenose dolphins (Tursiops truncatus) and B6C3F1 mice

Polybrominated diphenyl ethers (PBDEs) are an emerging contaminant of concern with low level exposures demonstrating toxicity in laboratory animals and wildlife, although immunotoxicity studies have been limited. Bottlenose dolphin peripheral blood leukocytes (PBLs) and mouse splenocytes were exposed to environmentally relevant DE-71 (a penta-PBDE mixture) concentrations (0-50 µg ml(-1) ) in vitro. Natural killer (NK) cell activity and lymphocyte (B and T cell) proliferation were evaluated using the parallelogram approach for risk assessment. This study aimed to substantiate results from field studies with dolphins, assess the sensitivities between the mouse model and dolphins, and to evaluate risk using the parallelogram approach. In mouse cells, NK cell activity increased at in vitro doses 0.05, 0.5 and 25 µg DE-71 ml(-1) , whereas proliferation was not modulated. In dolphin cells, NK cell activity and lymphocyte proliferation was not altered after in vitro exposure. In vitro exposure of dolphin PBLs to DE-71 showed similar results to correlative field studies; NK cell activity in mice was more sensitive to in vitro exposure than dolphins, and the parallelogram approach showed correlation with all three endpoints to predict risk in bottlenose dolphins.

A review of what is an emerging contaminant

A review is presented of how one defines emerging contaminants and what can be included in that group of contaminants which is preferably termed “contaminants of emerging concern”. An historical perspective is given on the evolution of the issues surrounding emerging contaminants and how environmental scientists have tackled this issue. This begins with global lead contamination from the Romans two millennia ago, moves on to arsenic-based and DDT issues and more recently to pharmaceuticals, cyanotoxins, personal care products, nanoparticles, flame retardants, etc. Contaminants of emerging concern will remain a moving target as new chemical compounds are continuously being produced and science continuously improves its understanding of current and past contaminants.

PCBs are associated with altered gene transcript profiles in arctic Beluga Whales (Delphinapterus leucas)

High trophic level arctic beluga whales (Delphinapterus leucas) are exposed to persistent organic pollutants (POP) originating primarily from southern latitudes. We collected samples from 43 male beluga harvested by Inuvialuit hunters (2008-2010) in the Beaufort Sea to evaluate the effects of POPs on the levels of 13 health-related gene transcripts using quantitative real-time polymerase chain reaction. Consistent with their role in detoxification, the aryl hydrocarbon receptor (Ahr) (r(2) = 0.18, p = 0.045 for 2008 and 2009) and cytochrome P450 1A1 (Cyp1a1) (r(2) = 0.20, p < 0.001 for 2008 and 2009; r(2) = 0.43, p = 0.049 for 2010) transcripts were positively correlated with polychlorinated biphenyls (PCBs), the dominant POP in beluga. Principal Components Analysis distinguished between these two toxicology genes and 11 other genes primarily involved in growth, metabolism, and development. Factor 1 explained 56% of gene profiles, with these latter 11 gene transcripts displaying greater abundance in years coinciding with periods of low sea ice extent (2008 and 2010). δ(13)C results suggested a shift in feeding ecology and/or change in condition of these ice edge-associated beluga whales during these two years. While this provides insight into the legacy of PCBs in a remote environment, the possible impacts of a changing ice climate on the health of beluga underscores the need for long-term studies.

Hexabromocyclododecanes in crucian carp and sediment from the major rivers in Korea

The concentration of hexabromocyclododecanes (HBCDs) was measured in crucian carp muscles and eggs and in surrounding sediments collected from the 3 major rivers in Korea. HBCDs were detected in all carp and sediment samples, indicating widespread contamination of this area by HBCD flame retardants. The ∑HBCD (sum of α-, β-, and γ-HBCDs) concentrations ranged from 0.19 to 13 ng g(-1)dry wt in sediments, 1.7 to 7.2 ng g(-1)lipid wt in carp eggs, and 4.8 to 6.6 ng g(-1)lipid wt in the muscle of carp. The α-diastereomer predominated in the crucian carp and γ-diastereomer predominated in sediments, accounting for 76% and 77% to the ∑HBCD, respectively. The ∑HBCD concentrations in carp and sediment samples collected along the rivers were higher than those in samples collected from an isolated pond, suggesting that the rivers are likely contaminated by HBCDs from the upstream or the environment surrounding the rivers. The diastereomer ratios in carp were different from those in commercial mixtures due to the enrichment of α-diastereomer in carp. The origin of this transition, however, is yet not known, since various transformation processes can lead to a change from the diastereomer ratio in commercial mixtures to that observed in the environment.

Polybrominated diphenyl ethers (PBDEs) in breast milk of Korea in 2011: current contamination, time course variation, influencing factors and health risks

Breast milk is a valuable biological specimen to assess maternal and infant exposure to polybrominated diphenyl ethers (PBDEs). In this study, 208 breast milk samples were collected from 89 participants during lactation period, at <7, 15, 30, and 90 days postpartum, in four cities in Korea, and were determined for 19 PBDE congeners. The total PBDE concentrations (ΣPBDE) ranged from 0.23 to 68.4 (mean: 2.73) ng/g lipid weight, and were within the ranges reported for European and Asian countries. Within a month of lactation after delivery, no significant changes were found in the PBDE concentrations. The predominance of BDE 153 rather than BDE 47 was found in the most samples that BDE 153 was detected, and was likely to be associated with stepwise debromination of BDE 209. No associations were found between PBDE concentrations in breast milk and demographic parameters, except for ΣPBDE with maternal age and delivery mode. Certain types of diet such as corn, seafood and nut correlated significantly with PBDE levels in breast milk. The estimated daily intakes of ΣPBDE for breast-feeding infants were lower than the guidelines proposed by the US EPA, indicating limited health risk from PBDEs through breast feeding.

Three decades (1983-2010) of contaminant trends in East Greenland polar bears (Ursus maritimus). Part 2: brominated flame retardants

Brominated flame retardants were determined in adipose tissues from 294 polar bears (Ursus maritimus) sampled in East Greenland in 23 of the 28years between 1983 and 2010. Significant linear increases were found for sum polybrominated diphenyl ether (ΣPBDE), BDE100, BDE153, and hexabromocyclododecane (HBCD). Average increases of 5.0% per year (range: 2.9-7.6%/year) were found for the subadult polar bears. BDE47 and BDE99 concentrations did not show a significant linear trend over time, but rather a significant non-linear trend peaking between 2000 and 2004. The average ΣPBDE concentrations increased 2.3 fold from 25.0ng/g lw (95% C.I.: 15.3-34.7ng/g lw) in 1983-1986 to 58.5ng/g lw (95% C.I.: 43.6-73.4ng/g lw) in 2006-2010. Similar but fewer statistically significant trends were found for adult females and adult males likely due to smaller sample size and years. Analyses of δ(15)N and δ(13)C stable isotopes in hair revealed no clear linear temporal trends in trophic level or carbon source, respectively, and non-linear trends differed among sex and age groups. These increasing concentrations of organobromine contaminants contribute to complex organohalogen mixture, already causing health effects to the East Greenland polar bears.

OH-initiated oxidation mechanisms and kinetics of 2,4,4'-Tribrominated diphenyl ether

2,4,4'-Tribromodiphenyl ether (BDE-28) was selected as a typical congener of polybrominated diphenyl ethers (PBDEs) to examine its fate both in the atmosphere and in water solution. All the calculations were obtained at the ground state. The mechanism result shows that the oxidations between BDE-28 and OH radicals are highly feasible especially at the less-brominated phenyl ring. Hydroxylated dibrominated diphenyl ethers (OH-PBDEs) are formed through direct bromine-substitution reactions (P1∼P3) or secondary reactions of OH-adducts (P4∼P8). Polybrominated dibenzo-p-dioxins (PBDDs) resulting from o-OH-PBDEs are favored products compared with polybrominated dibenzofurans (PBDFs) generated by bromophenols and their radicals. The complete degradation of OH adducts in the presence of O2/NO, which generates unsaturated ketones and aldehydes, is less feasible compared with the H-abstraction pathways by O2. Aqueous solution reduces the feasibility between BDE-28 and the OH radical. The rate constant of BDE-28 and the OH radical is determined to be 1.79 × 10(-12) cm(3) molecule(-1) s(-1) with an atmospheric lifetime of 6.7 days.

Accumulation of polybrominated diphenyl ethers (PBDEs) in mudsnails (Cipangopaludina cahayensis) did not increase with age

In this study, we examined concentrations of polybrominated diphenyl ethers (PBDEs) in mudsnails (Cipangopaludina cahayensis) and sediment samples from an electronic waste recycling area to investigate the correlation between PBDE accumulation and age. The results showed that PBDE accumulation did not increase with age, suggesting a dynamic balance between the uptake, depuration and biotransformation of PBDEs relative to growth dilution in mudsnails. We infer that this phenomenon is associated with low absorption efficiencies, rapid depuration rates and high biotransformation rates of PBDEs. BDE-209 contributed only up to about 5 %, whereas BDE-209 was the dominant congener and contributed up to 90 % of the total PBDEs in surface sediments. The difference in PBDE congener pattern between mudsnails and sediments showed a low bioaccumulation potential for these compounds in mudsnails.

Plant consumption by grizzly bears reduces biomagnification of salmon-derived polychlorinated biphenyls, polybrominated diphenyl ethers, and organochlorine pesticides

The present study characterizes the uptake and loss of persistent organic pollutants (POPs) in grizzly bears (Ursus arctos horribilis) by sampling and analyzing their terrestrial and marine foods and fecal material from a remote coastal watershed in British Columbia, Canada. The authors estimate that grizzly bears consume 341 to 1,120 µg of polychlorinated biphenyls (PCBs) and 3.9 to 33 µg of polybrominated diphenyl ethers daily in the fall when they have access to an abundant supply of returning salmon. The authors also estimate that POP elimination by grizzly bears through defecation is very low following salmon consumption (typically <2% of intake) but surprisingly high following plant consumption (>100% for PCBs and organochlorine pesticides). Excretion of individual POPs is largely driven by a combination of fugacity (differences between bear and food concentrations) and the digestibility of the food. The results of the present study are substantiated by a principal components analysis, which also demonstrates a strong role for log KOW in governing the excretion of different POPs in grizzly bears. Collectively, the present study's results reveal that grizzly bears experience a vegetation-associated drawdown of POPs previously acquired through the consumption of salmon, to such an extent that net biomagnification is reduced.

Bioaccumulation of polybrominated diphenyl ethers and several alternative halogenated flame retardants in a small herbivorous food chain

Little is known about the bioaccumulation behavior of polybrominated diphenyl ethers (PBDEs) and other halogenated flame retardants (HFRs) in plants and in herbivores. In the present study, PBDEs and several alternative HFRs (AHFRs) were examined in a small herbivorous food chain (paddy soils-rice plant-apple snails) from an electronic waste recycling site in South China. Mean concentrations of total PBDEs were 40.5, 1.81, and 5.54 ng/g dry weight in the soils, rice plant, and apple snails, respectively. Levels of total AHFRs in the samples were comparable to or even higher than those of PBDEs. The calculated plant to soil concentration ratios for most AHFRs (0.05-3.40) were higher than those for PBDEs (0.02-0.23), indicating the greater bioavailability of the AHFRs in the rice plant. All PBDE congeners and Dechlorane Plus (DP) isomers were biomagnified from the rice plant to apple snails, with mean biomagnification factors (BMFs) of 1.1-5.0.

Influence of age, season, body condition and geographical area on concentrations of chlorinated and brominated contaminants in wild mink (Neovison vison) in Sweden

The wild mink has gained acceptance as a sentinel species in environmental monitoring. However, only limited data are available in the literature on factors driving variability in concentrations of organic pollutants in this species. This study characterizes the differences in contaminant concentrations in subcutaneous fat of male mink from four different areas in Sweden and demonstrates how age, season and body condition influence concentrations of polychlorinated biphenyl (PCB) congeners, polybrominated diphenyl ether (PBDE) congeners (including methoxylated forms, MeO-PBDEs), as well as the pesticides dichlorodiphenyldichloroethylene (DDE), chlordane and hexachlorobenzene (HCB). The data were statistically treated using multiple regression and principal component analysis. The ∑PCB concentration and concentrations of PCB congeners 138, 156, 157, 180, 170/190, 189, 194, 206, 209 as well as PBDE 153/154 varied with age. Season had an influence on ∑PCB, PBDE 47 and PBDE 153/154 concentrations, as well as concentrations of most PCB congeners, with the exception of PCB 101, 110, 141 and 182/187. Lean mink had higher concentrations of most PCBs and PBDEs than mink with larger fat depots. The analyzed pesticides (DDE, oxychlordane, HCB) showed no systematic variation with season, age or body condition. The concentrations of MeO-PBDEs were generally low and 6MeO-PBDE 47 was the most commonly detected MeO-PBDE in mink from marine, brackish and freshwater areas. The results indicate that age, season and body condition are factors that may influence the concentrations of PCBs and PBDEs, and it is thus recommended to take these factors into account when analyzing mink exposure data.

Polybrominated diphenyl ether metabolism in field collected fish from the Gila River, Arizona, USA--levels, possible sources, and patterns

Polybrominated diphenyl ethers (PBDEs) were determined in fish collected from the Gila River, Arizona, a tributary of the Colorado River in the lower part of the Colorado River Basin. Fish samples were collected at sites on the Gila River downstream from Hayden, Phoenix, and Arlington, Arizona in late summer 2003. The Gila River is ephemeral upstream of the Phoenix urban area due to dams and irrigation projects and has limited perennial flow downstream of Phoenix due to wastewater and irrigation return flows. Fifty PBDE congeners were analyzed by high resolution gas chromatography/high resolution mass spectrometry using labeled surrogate standards in composite samples of male and female common carp (Cyrpinus carpio), largemouth bass (Micropterus salmoides) and channel catfish (Ictalurus punctatus). The predominant PBDE congeners detected and quantified were 47, 100, 153, 49, 28, and 17. Concentrations of total PBDEs in these fish ranged from 1.4 to 12700 ng g(-1) wet weight, which are some of the highest concentrations reported in fish from the United States. Differences in metabolism of several PBDE congeners by carp is clear at the Phoenix site; congeners with at least one ring of 2,4,5-substitution are preferentially metabolized as are congeners with 2,3,4-substitution.

Temporal monitoring of liver and kidney lesions in contaminated East Greenland polar bears (Ursus maritimus) during 1999-2010

Organohalogen contaminants bioaccumulate to high concentrations in tissues of polar bears (Ursus maritimus). The exposure levels are in the order to be toxic to inner organs like liver and kidney. We therefore investigated the temporal development of lesions in liver (n=115) and kidney (n=122) samples from East Greenland polar bears taken over the 12 year period from 1999 to 2010. Seven liver and seven kidney lesions were observed of which six were age-related. Controlling for this, the analyses showed that hepatic steatosis and renal cell infiltrations, glomerular sclerosis and tubular hyperplasia decreased over the investigated time period (all p<0.05). Similarly, hypertrophy of hepatic Ito cells, renal glomerular capillary wall thickening and interstitial fibrosis increased over the study period (all p<0.05). Regarding contaminant, concentrations of polybrominated diphenyl ethers in adipose tissue were negatively associated with hepatic mononuclear cell infiltrations (p=0.05) and a similar trend was found for Hg (p=0.09). Hexachlorobenzene was positively associated with portal cell infiltrations and hepatic lipid granulomas, while polychlorinated biphenyls were negatively associated with the prevalence of steatosis (both p<0.05) and a similar trend was found for hexachlorocyclohexanes (p=0.08). Mercury was positively correlated with the frequencies of hypertrophic Ito cells (p=0.002) and a similar trend was found for perfluorooctanesulfonic acid (p=0.07). In renal tissue, hexachlorocyclohexanes were positively associated with medullar hyaline casts (p=0.03) and a similar trend was found for cell infiltrations (p=0.08). There was a trend of trans-nonachlor being positively associated with glomerular sclerosis (p=0.06) while dichlorodiphenyltrichloroethanes were negatively associated with tubular hyperplasia (p=0.02). These results suggest that specific liver and renal lesions have decreased or increased over time and that long-range transported organohalogen contaminants and mercury may be among the co-factors responsible for these observations. These relationships are important to take into account when biomonitoring health and pollution in wildlife species such as polar bears.