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The Arctic Monitoring and Assessment Programme (AMAP) is a working group under the Arctic Council with the aim to monitor and assess temporal trends of contaminants in Arctic ecosystems. The Greenland AMAP Core programme was established to contribute to this effort. The Core programme includes three main components; routine monitoring, retrospective studies and new POP screening studies. The programme is based on an adaptive approach, which has led to changes throughout the years. An overview of the temporal trends during the last two to three decades is presently given together with selected examples of different characteristic trends of POPs. The results show how tissue banked samples and retrospective studies has helped in establishing time-series of compounds of emerging concern. Lastly, the statistical power of the Greenlandic time-series is discussed. The lesson learned is that trend monitoring improves with samples over time, and only pays off after decades of data are generated. [ABSTRACT FROM AUTHOR]

Abstract: We investigated polychlorinated biphenyls (PCBs), organochlorine pesticides (e.g. dichlorodiphenyltrichloroethane (DDT)), polybrominated diphenyl ethers (PBDEs) and methoxylated PBDEs (MeO-PBDEs), in six matrices (muscle, liver, kidney, adipose, blood, preen oil) of 17 white-tailed eagles from West Greenland sampled between 1997 and 2009. High inter-individual variation in contamination was found (PCBs: 0.49–1500 μg/g lipid weight (lw), DDTs: 0.23–910 μg/g lw, PBDEs: 0.01–24 μg/g lw, MeO-PBDEs: 0.001–0.59 μg/g lw), mostly due to age-related differences and not to temporal trends. One adult female (age > 5 years) displayed PCB levels up to 1500 μg/g lw in liver, which is the highest concentration ever reported in Arctic wildlife. Muscle generally contained the highest median levels, while adipose tissue displayed the lowest median levels on a lipid basis. No significant differences were found among tissues for MeO-PBDEs. Remarkably, we found distinct correlations (0.62 ≤ r ≤ 0.98; <0.0001 ≤ p ≤ 0.17) between levels of MeO-PBDEs and PBDEs, suggesting similar bioaccumulation pathways of PBDEs and MeO-PBDEs in white-tailed eagles. [Copyright &y& Elsevier]

The article presents a study which focuses on the abundance and rate of increase of Megaptera novaeangliae (humpback whales) in West Greenland.It mentions that an aerial line transect surveys of the density of humpback whales which were conducted between 1984 to 2007 were used for the estimation of the rate of increase on the summer feeding ground. It says that a theoretical growth rate of a humpback whale population ranging from one percent to 11% is revealed by the matrix model. Moreover, the development of a correction for availability was based on time-depth-recorder information.

Serum samples from 419 polar bears (Ursus maritimus) from Svalbard and the Barents Sea (collected 1990-2000) and 108 polar bears from East Greenland (collected 1999-2004) were assayed for antibodies against Toxoplasma gondii using the modified agglutination test. Antibody prevalences were 3.6% among cubs dependent on their mothers and 21.4% among subadults and adults. Among subadults and adults there was an interaction between population and sex, with similar prevalences among females (Svalbard = 19.5%, Greenland = 18.0%), but a high frequency among Svalbard males (28.7%) as compared to Greenland males (5.8%). The pattern was also significant after correcting for differences in age distribution. The sex-population interaction term is believed to be connected to area- and sex-specific feeding ecology. The prevalences of antibodies against T. gondii in Svalbard and Greenland were high compared to previously reported findings in polar bears from Russian and Alaskan areas. [ABSTRACT FROM AUTHOR]

Abstract: Toxaphene contamination of minke whales (Balaenoptera acutorostrata) from North Atlantic waters was examined for the first time. Total toxaphene and ΣCHB (sum of 11 chlorobornanes) concentrations in blubber samples ranged from 170±110 and 41±39ng/g lipid weight (l.w.) for female minke whales from southeastern Greenland to 5800±4100 and 1100±780ng/g l.w. for males from the North Sea, respectively. Very large variations in toxaphene concentrations among sampling areas were observed suggesting a spatial segregation of minke whales. However, much of the apparent geographical discrimination was explained by the seasonal fluctuation of animal fat mass. Patterns of CHBs in males revealed that recalcitrant CHBs were in higher proportions in animals from the more easterly areas than in animals from the more westerly areas. This trend may be influenced by the predominance of the US, over the European, input of toxaphene to North Atlantic waters. [Copyright &y& Elsevier]

A well-defined subsample of 128 subadult (3-5 years) polar bears (Ursus maritimus) from 19 sampling years within the period 1984-2006 was investigated for perfluoroalkyl contaminants (PFCs). Linear regression analysis of logarithmic-transformed median concentrations showed significant annual increases for PFOS (4.7%), PFNA (6.1%), PFUnA (5.9%), PFDA (4.3%), PFTrA (8.5%), PFOA (2.3%), and PFDoA (5.2%). For four of the PECs, a LOESS smoother model provided significantly better descriptions, revealing steeper linear annual increases for PFOSA of 9.2% after 1990 and between 18.6 and 27.4% for PFOS, PFDA, and PFTrA after 2000. Concentrations of ΣPFCs, by 2006, exceeded the concentrations of all conventional OHCs (organohalogen compounds), of which several have been documented to correlate with a number of negative health effects, If the PFC concentrations in polar bears continue to increase with the steepest observed trends, then the lowest no-adverse-effect level (NOAEL) and lowest-adverse-effect level (LOAEL) detected for rats and monkeys will be exceeded in 2014-2024. In addition, the rapidly increasing concentrations of PFCs are likely to cause cumulative and combined effects on the polar bear, compounding the already detected threats from OHCs. [ABSTRACT FROM AUTHOR]

Exposure levels of persistent organic pollutants, such as polychlorinated biphenyls and DDTs, are high in Arctic apex predators and Inuit peoples and are suspected to have negative impacts on their immune systems. We conducted a controlled generational study on liver tissue and ethylenediaminetetraacetic acid blood cytokine and acute-phase protein (APP) mRNA expressions using reverse transcriptionase–polymerase chain reaction in West Greenland sledge dogs ( Canis familiaris); contaminated minke whale ( Balaenoptera acutorostrata) blubber serves as dietary pollutant source. Two of seven blood cytokine expressions (IL-6 and IL-12) and three of five APP expressions (haptoglobin [HP], heat shock protein, and fatty acid–binding protein [FABP]) were lowest in the exposed group, whereas the remaining five blood cytokine expressions (IL-2, IL-10, IFN-γ, TNF-α, and TGF-β) and two APP expressions (MT1 and MT2) were highest in the exposed group. In liver tissue, three cytokine expressions (IL-10, IFN-γ, and TNF-α) and two APP expressions (MT1 and MT2) were highest in the exposed group, and the remaining cytokine and APP expressions were lowest in the exposed group. Of these, the liver tissue expression of HP and FABP was significantly lowest in the exposed group (both p < 0.05). As a consequence of our findings, we suggest that a daily intake of 50 to 200 g polluted whale blubber is associated with a genotoxic decrease in HP and FABP gene expression in the liver of sledge dog and possibly of other top mammalian marine predators and consumers in the Arctic, indicating a restricted acute-phase reaction and insufficient immune response. Finally, HP and FABP liver expression appear to be new and sensitive biomarkers of organohalogen compound exposure. [ABSTRACT FROM AUTHOR]

Mercury concentrations in hair from 397 Greenland polar bears (Ursus maritimus) sampled between 1892 and 2001 were analyzed for temporal trends. In East Greenland the concentrations showed a significant (p < 0.0001, n = 27) increase of 3.1%/year in the period 1892–1973. In Northwest Greenland, a similar (p < 0.0001, n = 69) increase of 2.1%/year was found, which continued until 1991, when the most recent samples were obtained. In East Greenland, a significant (p = 0.009, n = 322) decrease of 0.8%/year was observed after 1973. Two Northwest Greenland samples from 1300 A.D. had a mean value of 0.52 mg/kg of dry weight, which can be considered as a baseline level. The Hg concentration during 1985–1991 from Northwest Greenland (mean value of 7.45 mg/kg of dry weight) was more than 14-fold higher than the assumed baseline level from 1300 A.D. from the same region (i.e., about 93% anthropogenic). Although a decrease was found in East Greenland after 1973, the concentration is still ca. 11-fold higher than the baseline level (i.e., about 90% anthropogenic). [ABSTRACT FROM AUTHOR]

Persistent organochlorine (OC) contaminants (PCBs, DDTs, chlordanes (CHLs), dieldrin, hexachlorocyclohexanes (HCHs), chlorobenzenes (CBzs)) were determined in adipose tissue of 92 polar bears (Ursus maritimus) sampled between 1999 and 2001 in central East Greenland (69°00′N to 74°00′N). OC data were presented from subadults (S: females: ×5 years and males: ×6 years), adult females (F: ×5 years) and adult males (M: ×6 years). Summed chlorobiphenyl (ΣCBs) concentrations (41 congeners including co-eluters), ΣCHLs and ΣDDTs were the dominant classes of OCs. ΣCBs concentrations were found to be 6470, 8240 and 9100 ng/g lipid weight (lw) i subadults, adult females and adult males, respectively. The corresponding figures were: 2010 (S), 2220 (F) and 1710 (M) ng/g lw for ΣCHLs and 462 (S), 462 (F) and 559 (M) ng/g lw for ΣDDTs. The dominant CB congeners were CB153 (32.3%), CB180 (21.4%), CB170 (12.2%) and CB138 (11.0%). The metabolite p,p′-DDE (88.2%) dominated the ΣDDTs, while oxychlordane was the dominant (57.1%) CHL-related compound. Concentrations of ΣCBs, ΣCBzs, ΣDDTs, mirex and dieldrin were highest in adult males, whereas concentrations of ΣHCHs were lower than in adult females but not than those in subadults. Adult females had the lowest concentrations of ΣCBzs, mirex and dieldrin. Concentrations of ΣCHLs were lowest in adult males, intermediate in subadults and highest in adult females. ΣCB, ΣHCH and ΣCHL concentrations showed high seasonal variability in adult females but remained relatively constant in adult males and subadults. In general, the OC levels in females appeared to be highest in March and lowest in January or September. Concentrations of ΣCBzs and dieldrin showed seasonal variability in all three groups, with a maximum in March in adult females. ΣCBz concentrations in adult males and subadults of both sexes peaked in April–July, and dieldrin concentrations peaked in April–July in subadults, but not until August in adult males. ΣDDT concentrations increased from January to a maximum in April–July for subadults and in August for adults. Temporal trends within the last decade were examined by comparing the present data to the concentrations reported in samples from 1990 from the same region. ΣCB, p,p′-DDE and ΣHCH concentrations in 1999–2001 were 22.1%, 66.3% and 39.3% lower than the 1990 concentrations, respectively. in contrast, ΣCHL and dieldrin concentrations showed differences amongst sex and age groups in the temporal trends, where present concentrations are between 24.4% to 69.3% and 27.0% to 69.0% lower, respectively, relative to the 1990 levels. However, power analysis suggested that firm conclusions could not be drawn regarding the general time trend based on these two sampling periods. The range of half-lives of the various OC classes were estimated to lie between 4.5 and 20.6 years depending on the age and sex groups considered. [Copyright &y& Elsevier]

Samples of 150 narwhals obtained in different years from two West Greenland areas, Avanersuaq and Uummannaq, were compared for concentrations of and regional differences in heavy metals and organochlorines and stable-carbon and nitrogen isotopes. Cadmium, Hg, and Se concentrations increased in the first 3–4 years of the animal''s life, after which no dependence on age was observed. Females had significantly higher concentrations of Cd in all tissues and of Hg and Se in liver than males. No consistent difference in metal levels between narwhals from Avanersuaq and Uummannaq was found. Year-to-year variation in metal levels at one location was larger than the geographical variation. Metal levels were within the range of previous published results for narwhals from Arctic Canada. Organochlorine (OC) concentrations in blubber of narwhals were dependent on age and sex. Females showed decreasing OC concentration in the first 8–10 years, while for males increases were detected in the first few years of life, after which the concentrations became stable. Few statistical differences in mean OC concentrations among individuals were observed. However, narwhals from Avanersuaq in 1993 had the lowest levels, indicating a temporal decrease of ∑PCBs. ∑PCBs, DDTs, HCHs and toxaphenes seem to be at similar levels in West Greenland and Arctic Canada, which can be explained by the close winter distributions of populations as well as large ranges in concentrations, time span, number of analyses and the size/age composition of the data. PCB and DDT concentrations in West Greenland narwhals were half those found in East Greenland and Svalbard. Stable-carbon isotope ratios in muscle of 150 narwhals showed a decreasing trend in the first year when they gradually reduced their dependency on mother''s milk, after which they became relatively stable. δ15 N values were significantly higher in samples from Uummannaq in 1993 compared to samples from Avanersuaq in 1984 and 1985 indicating that the diet of the narwhals in Uummannaq was at a higher trophic level. However, only a few significant correlations were found between stable isotope ratios and metal and OC concentrations. [Copyright &y& Elsevier]

Knowledge of contaminant levels in Greenland biota has increased substantially in recent years, particularly for persistent organic pollutants. This paper reviews and updates knowledge of spatial and temporal trends of Cd, Hg and organochlorines (PCBs, DDTs, HCHs, HCB and chlordane-related compounds) in Greenland terrestrial, freshwater and marine biota. The most comprehensive studies of spatial trends of Cd and Hg in the terrestrial ecosystem concern lichens, with relatively complete coverage, and caribou (Rangifer tarandus), with coverage mainly in different regions of central West Greenland and Southwest Greenland. The Arctic char (Salvelinus alpinus) is the only freshwater organism for which studies of spatial trends of Hg levels have been completed. Information on spatial trends of Cd and Hg in the marine environment is available from studies of fish, seabirds, ringed seals (Phoca hispida) and polar bears (Ursus maritimus). Geographical patterns of Cd and Hg in Greenland biota were not always consistent among different species or different studies. In landlocked Arctic char the concentrations of Hg decreased from south to north. In marine animals levels of Hg tended to be higher in East Greenland than in West Greenland and Cd levels were highest in biota from Disko Island in central West Greenland. The observed regional differences are difficult to explain but in most cases the causes appear to be natural rather than anthropogenic. Only a few time series covering the last 20 years exist for Cd and Hg. The one time series indicating a temporal change is for ringed seals in Northwest Greenland, which shows an increasing trend of Hg and a decreasing trend of Cd since 1984. Whether the changes reflect anthropogenic inputs, seal behaviour or other environmental factors is unknown. The most significant new insights have concerned organochlorines. In general, levels of these compounds were very low in terrestrial biota compared to marine species. Concentrations in landlocked Arctic char were highest in Southeast Greenland and lowest in Northwest and Northeast Greenland. Marine species from East Greenland had consistently higher levels of ΣPCB, ΣDDT and ΣHCH than marine species from West Greenland. Very few data exist to evaluate temporal changes of organochlorine levels in Greenland biota, and this is the most significant knowledge gap at present. The most pronounced change observed was a decrease of 78% in ΣPCB levels in polar bears from East Greenland from 1990 to 2000. Levels of ΣHCH in shorthorn sculpins (Myoxocephalus scorpius) and seals from both central West Greenland and central East Greenland appear to have decreased since 1994. Increasing trends of ΣDDT from 1994 until now were found in both sexes of seals as well as in male sculpins from central West Greenland. [Copyright &y& Elsevier]

Movements and behavior of top marine predators are often closely linked with productive oceanic fronts or regional prey aggregations. Consequently, it is of interest to quantify habitat needs and preferences, which can facilitate predictions of conditions favoring persistence and success. Multivariate habitat models of movements and dive behavior of narwhals (Monodon monoceros, Linnaeus) in the eastern Canadian high Arctic and West Greenland were developed using data collected from satellite telemetry studies on three separate sub-populations. Twenty-six narwhals were captured between 1993 and 2000 and fitted with satellite-linked time-depth recorders. Geographic positions of whales at 24-h time steps were linked to dive behavior variables compressed on a daily scale, including numbers of dives to different target depths or durations, time near the surface, daily dive rate, and travel speed. Whale movements and behavior were linked to biophysical variables in a raster format using a GIS (bathymetry, bottom topography, bottom temperature, and distance from the coastline) and analyzed using linear and generalized linear mixed models, accounting for temporal autocorrelation and random variation among individuals. Models suggested that several physical variables described narwhal behavior, predominantly bathymetry and distance from the coastline (particularly deep or long dives). Other descriptor variables, such as size category and sex, also explained portions of the model variability, particularly for shallow dives, surface time, and dive rates. Bottom temperature (°C) was the strongest predictor of all dive behaviors when narwhal location data were restricted to periods with available temperatures. The bottom temperature range and gradient selected by narwhals on their wintering grounds often coincided with areas of concurrent high density of Greenland halibut (Reinhardtius hippoglossoides, Walbaum) and predictable open water in winter pack ice in Baffin Bay. These quantitative habitat models made it possible to reconcile the behavioral traits of narwhals with dynamic environmental factors. [ABSTRACT FROM AUTHOR]

The Greenland marine food chains contain high levels of cadmium, mercury and selenium. Concentrations of cadmium in the kidney of ringed seals (Phoca hispida) from the municipalities of Qaanaaq and Upernavik (Northwest Greenland) are among the highest recorded in the Arctic. The purpose of the study was to determine whether cadmium-induced damage in the kidneys and the skeletal system could be detected among 100 ringed seals from Northwest Greenland. The cadmium concentrations in the kidney cortex ranged from 0 to 248 μg/g wet weight (mean=44.5, N=100) in the 99 kidneys examined. Experience from cadmium-poisoned humans and laboratory mammals indicates that concentrations above 50–200 μg/g wet wt. may induce histopathological changes. Overall, 31 of the ringed seals had cadmium concentrations in the kidney cortex above 50 μg/g wet wt., 11 had concentrations above 100 and one had a concentration above 200 μg/g wet wt. Obvious histopathological changes (categorised mainly as glomerulonephritis) were found in 10 of the seals; however, none of these changes could be attributed to cadmium-induced renal damage (mainly tubulopathy) as described for other species. Damage to the proximal kidney tubules is known to induce demineralisation of the skeletal system (Fanconi''s syndrome). Therefore, the three lowest lumbar vertebrae were scanned in 91 seals to measure the content of calcium. The 10 cases of nephropathy could neither be linked to the degree of mineralisation of the skeleton nor to the cadmium concentrations. Furthermore, the degree of mineralisation of the skeleton was not correlated with the cadmium concentration, age or sex. It can therefore be concluded that despite high levels of cadmium, none of the ringed seals showed any signs of cadmium-induced nephropathy or osteodystrophy. This might be explained by the composition of the ringed seals diet, which contains high levels of vitamin D, calcium, phosphorus, zinc, selenium and protein. These elements are all likely to counteract cadmium-induced damage. It is speculated that ringed seal are not particularly vulnerable to osteodystrophy, due to their continuous growth (bone mineralisation) throughout life and the oestrogen hormonal activity of females throughout life. [Copyright &y& Elsevier]

We quantified blubber concentrations of vitamins A (retinol) and E (α-tocopherol) and evaluated associations with persistent organic pollutants (ΣPOPs) in 14 highly-contaminated killer whales (Orcinus orca) sampled in Greenland from 2012 to 2014. We considered the influence of blubber depth, sex/age class and diet (based on biomass % of major fatty acids) in these relationships. Blubber concentrations of vitamin A averaged 34.1 ± 4.7 μg g−1 wet weight (ww) and vitamin E averaged 35.6 ± 4.4 μg g−1 ww. Although overall vitamin A concentrations did not vary between inner (closer to the muscle) and outer (closer to the skin) blubber layer or between sub-adults and adult females, concentrations in the outer layer of sub-adults were lower compared to the outer layer of adult females (p = 0.03). Outer layer may therefore reflect age accumulation of vitamin A, while in the more active inner layer, age effects might be masked by metabolic needs such as lactation. Neither diet nor ΣPOPs affected vitamin A variation, suggesting this vitamin is highly regulated in the body. Given the high exposures in these killer whales, vitamin A might not be a sensitive biomarker for POPs adverse effects. Vitamin E concentrations were significantly higher in inner compared to outer layer (p < 0.001), likely associated with blubber composition, suggesting that biopsies may not fully represent vitamin E concentrations in blubber. Age-accumulation of vitamin E also occurred with higher concentrations in adult females compared to sub-adults, independent of blubber depth (p < 0.01). Diet, ΣPOPs, and an interaction between these two variables significantly affected vitamin E variation in inner blubber, explaining 91% of this variation. The negative relationship between ΣPOPs (especially Σdichlorodiphenyltrichloroethane (DDT) and Σchlordanes in outer layers) and vitamin E was observed only in killer whales with a diet poorer in polyunsaturated fatty acids, suggested that killer whales feeding more consistently on marine mammals in Arctic environments over a fish-based diet, may be at higher risk of POP-induced disruption in vitamin E homeostasis. Considering diet is therefore important to understand the potential effects of elevated contaminant exposures on levels of certain essential nutrients, i.e., vitamin E, in killer whales. Image 1 • Killer whale vitamin A levels were not related to blubber depth, diet or ΣPOP. • Vitamin A showed age deposition in outer, but not inner blubber layers. • Higher vitamin E levels in adult females than sub-adults indicated age-deposition. • Decreasing vitamin E from inner to outer blubber related to fatty acid composition. • Negative ΣPOP-vitamin E association for animals with diets richer in marine mammals. [ABSTRACT FROM AUTHOR]

Abstract: To demonstrate the ability to assess long-term hypothalamic–pituitary–adrenocortical (HPA) axis activity in polar bears (Ursus maritimus), a pilot study was conducted in which cortisol concentrations was analyzed in hair from 7 female (3–19years) and 10 male (6–19years) East Greenland polar bears sampled in 1994–2006. The hair was chosen as matrix as it is non-invasive, seasonally harmonized, and has been validated as an index of long-term changes in cortisol levels. The samples were categorized according to contamination: eight were clean (2 females, 6 males), 5 had been contaminated with bear blood (2 F, 3 M), and 4 with bear fat (3 F, 1 M). There was no significant difference in cortisol concentration between the three categories after external contamination was removed. However, contaminated hair samples should be cleaned before cortisol determination. Average hair cortisol concentration was 8.90pg/mg (range: 5.5 to 16.4pg/mg). There was no significant correlation between cortisol concentration and age (p=0.81) or sampling year (p=0.11). However, females had higher mean cortisol concentration than males (females mean: 11.0pg/mg, males: 7.3pg/mg; p=0.01). The study showed that polar bear hair contains measurable amounts of cortisol and that cortisol in hair may be used in studies of long-term stress in polar bears. [ABSTRACT FROM AUTHOR]

Abstract: Fluctuating asymmetry (FA) was studied in skulls of 283 polar bears (Ursus maritimus) sampled in East Greenland from 1892 to 2002. Fourteen metric bilateral traits in skull and lower jaw were measured and compared between polar bears born until 1960 (n=94) and from 1961 (n=189). The period 1892–1960 was chosen to represent a period prior to appearance of organohalogens (polychlorinatedbiphenyls [PCBs], dichlorodiphenyltrichloroethanes [DDTs], hexacyclohexanes [HCHs], chlordanes [CHLs], hexachlorobenzene [HCB], polybrominateddiphenylethers [PBDEs] and dieldrin) originating from long-range transport to East Greenland from southern latitudes. The period 1961–2002 represents the period when polar bears have been exposed to organohalogens. During this latter period, the level of organochlorines is believed to have increased from 1960 to the late 1980s followed by a likely decrease from 1990 to 2002. Within this later period, other compounds such as, e.g., polybrominated flame retardants are believed to have increased throughout the period. Two different analysis showed, that the degree of fluctuating asymmetry did not differ statistically between the two periods in ten of thirteen traits (one trait excluded due to high measurement error). In fact, when significant differences were found in four of the traits, the fluctuating asymmetry was lower in skulls sampled after 1960. The degree of fluctuating asymmetry was higher in adults than in subadults for 6 of the 14 traits, whereas a higher degree of fluctuating asymmetry was found for only one trait in one of the analyses for subadults relative to adults. Females had a higher degree of fluctuating asymmetry than males in one trait. A time trend analysis did find fluctuations over time for five traits but the relationship was weak as the trend appeared to occur by chance due to the high number of regressions analysed (n=42). A correlation analysis of FA versus the sum concentrations of various classes of organohalogens in adipose tissue from a subsample of 94 recently collected polar bears (1999–2002) did not show a trend either. Hence, the present study could not document a relationship between skull asymmetry in polar bears and periods with different exposure to organohalogens. These findings are possibly influenced by nutritional status, genetic factors, a subeffect exposure of organohalogens or confounded by other environmental factors (e.g. temperature) within the two investigated periods. [Copyright &y& Elsevier]

The monitoring of legacy contaminants in sentinel northern marine mammals has revealed some of the highest concentrations globally. However, investigations into the presence of chemicals of emerging Arctic concern (CEACs) and other lesser-known chemicals are rarely conducted, if at all. Here, we used a nontarget/suspect approach to screen for thousands of different chemicals, including many CEACs and plastic-related compounds (PRCs) in blubber/adipose from killer whales (Orcinus orca), narwhals (Monodon monoceros), long-finned pilot whales (Globicephala melas), and polar bears (Ursus maritimus) in East Greenland. 138 compounds were tentatively identified mostly as PRCs, and four were confirmed using authentic standards: di(2-ethylhexyl) phthalate (DEHP), diethyl phthalate (DEP), di(2-propylheptyl) phthalate (DPHP), and one antioxidant (Irganox 1010). Three other PRCs, a nonylphenol isomer, 2,6-di-tert-butylphenol, and dioctyl sebacate, exhibited fragmentation patterns matching those in library databases. While phthalates were only above detection limits in some polar bear and narwhal, Irganox 1010, nonylphenol, and 2,6-di-tert-butylphenol were detected in >50% of all samples. This study represents the first application of a nontarget/suspect screening approach in Arctic cetaceans, leading to the identification of multiple PRCs in their blubber. Further nontarget analyses are warranted to comprehensively characterize the extent of CEAC and PRC contamination within Arctic marine food webs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Persistent organic pollutants (POP) are environmental contaminants transported over long distances to the Arctic where they biomagnify in marine mammals subsistence hunted by Inuit and may therefore affect human health. Marine mammals in east Greenland are known to have the highest POP concentrations in the circumpolar Arctic area. Due to high intake of marine mammals, east Greenlandic Inuit likewise have the highest POP body burdens across the Arctic. This cross-sectional study aims to investigate the levels of POP and metals in Inuit with a high intake of top predatory species including killer whales and polar bears. Study participants include 37 men and 21 women from Kulusuk, Tasiilaq and Ittoqqortoormiit during year 2013-2015. Lipophilic POP (11 organochlorine-pesticides, 14 polychlorinated-biphenyls (PCB), 10 polybrominated diphenyl ethers), polyunsaturated fatty acids (PFUA) and cotinine were determined in plasma. Fifteen perfluoroalkylated substances (PFAS) were measured in serum and urine and the renal clearance was estimated. Finally the concentration of 10 metals were measured in whole blood. The median age was 38 years, Ittoqqortoormiit Inuit being the oldest. The smoking rate was around 70%, and Kulusuk participants had the lowest PFUA concentrations. Significant municipality differences were observed for lipophilic POP, serum PFAS, mercury, arsenic and selenium with highest concentrations in Ittoqqortoormiit Inuit. Males had higher blood concentrations of PFAS and lead. The estimated PFAS renal clearance and ratio of urine to serum were significantly higher for females, suggesting a sex difference in excretion via the kidney, maybe partly because men had higher serum PFAS concentrations. We observed that Inuit with intake of >200 g polar bear per week had significantly higher levels of PCB, PFAS, arsenic and selenium. In summary, the level of blood POP and heavy metals seems to relate to sex and the frequency intake of meat from marine mammals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The Earth's polar regions are low rates of inter- and intraspecific diversification. An extreme mammalian example is the Arctic ringed seal (Pusa hispida hispida), which is assumed to be panmictic across its circumpolar Arctic range. Yet, local Inuit communities in Greenland and Canada recognize several regional variants; a finding supported by scientific studies of body size variation. It is however unclear whether this phenotypic variation reflects plasticity, morphs or distinct ecotypes. Here, we combine genomic, biologging and survey data, to document the existence of a unique ringed seal ecotype in the Ilulissat Icefjord (locally 'Kangia'), Greenland; a UNESCO World Heritage site, which is home to the most productive marine-terminating glacier in the Arctic. Genomic analyses reveal a divergence of Kangia ringed seals from other Arctic ringed seals about 240 kya, followed by secondary contact since the Last Glacial Maximum. Despite ongoing gene flow, multiple genomic regions appear under strong selection in Kangia ringed seals, including candidate genes associated with pelage coloration, growth and osmoregulation, potentially explaining the Kangia seal's phenotypic and behavioural uniqueness. The description of 'hidden' diversity and adaptations in yet another Arctic species merits a reassessment of the evolutionary processes that have shaped Arctic diversity and the traditional view of this region as an evolutionary freezer. Our study highlights the value of indigenous knowledge in guiding science and calls for efforts to identify distinct populations or ecotypes to understand how these might respond differently to environmental change., (© 2023 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.)

Background: Perfluoroalkyl substances (PFASs) are ubiquitous global contaminants that do not readily biodegrade and are therefore routinely found worldwide in wildlife, humans, and the environment. There is a paucity of global assessments to understand regional and continental differences in exposure to PFASs and the associated health risks, including those for Indigenous Arctic communities who consume high trophic marine diets. We aimed to estimate the long-term exposure of dietary PFASs from consumption of polar bear and ringed seal meat and establish its association with blood serum concentrations of PFASs in Inuit in Ittoqoortoormiit (Scoresby Sound), East Greenland. We also aimed to assess the risk of immune suppression on the basis of European Food Safety Authority (EFSA) thresholds for weekly intake and blood serum concentrations of PFASs. Last, we conducted a worldwide risk assessment based on blood concentrations of PFASs emphasising Arctic exposure in a global context., Methods: In this mixed-methods study, we conducted interviews to compare dietary exposure of PFASs in anonymous, non-pregnant, Inuit adults (aged ≥18 years) from full-time or part-time hunter families in Ittoqoortoormiit, East Greenland with ESFA toxic threshold values for tolerable weekly intake of the four most immunotoxic PFASs (∑ 4 PFAS; perfluorooctanoic acid, perfluorononanoic acid, perfluorohexanesulfonic acid, and perfluorooctane sulfonate). Independent hospital staff from the local hospital randomly selected participants using simple randomisation using a telephone directory. Blood serum concentrations were then compared with EFSA risk categories: low (0·7-9·5 ng/mL), moderate (>9·5-17·5 ng/mL), high (>17·5-31·9 ng/mL), and severe (>31·9 ng/mL). We also reviewed the available scientific literature of ∑ 4 PFAS concentrations in human blood to place the Inuit dataset in a broader global context., Findings: Between Sept 21, and Oct 2, 2015, 22 participants were enrolled in the study, of which 12 were male and ten were female. Sex data were obtained from personal social security numbers and options were male or female. As a result of a subsistence diet high in marine mammal muscle, 322 (92%) of 350 people in the Ittoqoortoormiit cohort exceeded the established immunotoxic thresholds of ∑ 4 PFASs set by EFSA's tolerable weekly intake of 4·4 ng/kg, and 301 (86%) were in the most severe risk category (>31·9 ng/mL) based on blood serum concentrations. This Inuit cohort had the highest non-occupational long-term exposure to PFASs worldwide despite their remote location relative to industrial sources. Using country-wide average values across global studies, we found that blood serum concentrations of PFASs in populations from European countries, North America, the Arctic, and Australia were generally higher than those in South America, Africa, and mainland Asia, with the highest concentrations found in people from USA, Canada, Greenland, Faroe Islands, Denmark, Iceland, Norway, Sweden, the UK, Spain, Poland, and Australia. These high exposure countries all fall within the EFSA moderate-risk and high-risk categories., Interpretation: PFAS contamination of the environment and human populations occurs worldwide. This pollution not only poses substantial risks for immune system adverse events but also cardiovascular, cancerous, and reproductive endpoints. Data on such PFAS exposure is scarce in numerous countries. Therefore, it is important to also map out the exposure in these countries to enable a thorough global assessment of exposure and risks., Funding: Danish Cooperation for Environment in the Arctic., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Arctic Indigenous Peoples are among the most exposed humans when it comes to foodborne mercury (Hg). In response, Hg monitoring and research have been on-going in the circumpolar Arctic since about 1991; this work has been mainly possible through the involvement of Arctic Indigenous Peoples. The present overview was initially conducted in the context of a broader assessment of Hg research organized by the Arctic Monitoring and Assessment Programme. This article provides examples of Indigenous Peoples' contributions to Hg monitoring and research in the Arctic, and discusses approaches that could be used, and improved upon, when carrying out future activities. Over 40 mercury projects conducted with/by Indigenous Peoples are identified for different circumpolar regions including the U.S., Canada, Greenland, Sweden, Finland, and Russia as well as instances where Indigenous Knowledge contributed to the understanding of Hg contamination in the Arctic. Perspectives and visions of future Hg research as well as recommendations are presented. The establishment of collaborative processes and partnership/co-production approaches with scientists and Indigenous Peoples, using good communication practices and transparency in research activities, are key to the success of research and monitoring activities in the Arctic. Sustainable funding for community-driven monitoring and research programs in Arctic countries would be beneficial and assist in developing more research/monitoring capacity and would promote a more holistic approach to understanding Hg in the Arctic. These activities should be well connected to circumpolar/international initiatives to ensure broader availability of the information and uptake in policy development., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2022. Published by Elsevier B.V. All rights reserved.)

Mercury has become a ubiquitous hazardous element even ending up in pristine areas such as the Arctic, where it biomagnifies and leaves especially top predators vulnerable to potential health effects. Here we investigate total mercury (THg) concentrations and dietary proxies for trophic position and habitat foraging (δ 15 N and δ 13 C, respectively) in fur of 30 Arctic wolves collected during 1869-1998 in the Canadian High Arctic and Greenland. Fur THg concentrations (mean ± SD) of 1.46 ± 1.39 μg g -1 dry weight are within the range of earlier reported values for other Arctic terrestrial species. Based on putative thresholds for Hg-mediated toxic health effects, the studied Arctic wolves have most likely not been at compromised health. Dietary proxies show high dietary plasticity among Arctic wolves deriving nutrition from both marine and terrestrial food sources at various trophic positions. Variability in THg concentrations seem to be related to the wolves' trophic position rather than to different carbon sources or regional differences (East Greenland, the Foxe Basin and Baffin Bay area, respectively). Although the present study remains limited due to the scarce, yet unique historic study material and small sample size, it provides novel information on temporal and spatial variation in Hg pollution of remote Arctic species., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Polar bears are susceptible to climate warming because of their dependence on sea ice, which is declining rapidly. We present the first evidence for a genetically distinct and functionally isolated group of polar bears in Southeast Greenland. These bears occupy sea-ice conditions resembling those projected for the High Arctic in the late 21st century, with an annual ice-free period that is >100 days longer than the estimated fasting threshold for the species. Whereas polar bears in most of the Arctic depend on annual sea ice to catch seals, Southeast Greenland bears have a year-round hunting platform in the form of freshwater glacial mélange. This suggests that marine-terminating glaciers, although of limited availability, may serve as previously unrecognized climate refugia. Conservation of Southeast Greenland polar bears, which meet criteria for recognition as the world's 20th polar bear subpopulation, is necessary to preserve the genetic diversity and evolutionary potential of the species.

Polonium-210 ( 210 Po) is a radionuclide sentinel as it bioaccumulates in marine organisms, thereby being the main contributor to committed dietary doses in seafood consumers. Although seafood and marine mammals are an important part of the traditional Inuit diet, there is a general lack of information on the 210 Po concentrations in the Greenlandic marine food chain leading to the human consumer. Here, we determine background 210 Po concentrations in edible parts of different marine organisms from Greenland and provide a dose assessment. Blue mussels (Mytilus edulis), organs of ringed seal (Pusa hispida) and polar bear (Ursus maritimus) displayed significantly elevated 210 Po concentrations in respect to all other studied organisms (p < 0.001). 210 Po concentrations ranged from 0.02 Bq kg -1 , w.w. in Greenland halibut (Reinhardtius hippoglossoides) muscle to 78 Bq kg -1 , w.w. and 202 Bq kg -1 , w.w. in ringed seal muscle and kidneys, respectively. 210 Po concentration ratio for edible parts increases in the order bladderwrack (Fucus Vesiculosus), northern shrimp (Pandalus borealis), blue mussels, and from fish species to ringed seal and polar bear. 210 Po distribution in fish, ringed seal, and polar bear follows a general pattern, the lowest concentrations were in muscle, and the highest concentrations were in the organs involved in metabolism. The derived 210 Po annual absorbed dose in edible parts of studied marine organisms are several orders of magnitude lower than the recommended dose rate screening value of 10 μGy h -1 . Effective doses from intake of 210 Po to Greenland average children (1.4 mSv y -1 ), and high seafood and marine mammal consumers (2 mSv y -1 for adults and 3.6 mSv y -1 for children) are higher than the world average annual effective dose due to ingestion of naturally occurring radionuclides., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Environmental exposure to bisphenols and benzophenone UV filters has received considerable attention due to the ubiquitous occurrence of these contaminants in the environment and their potential adverse health effects. The occurrence of bisphenols and benzophenone UV filters is well established in human populations, but data is scarce for wildlife, and especially for raptors (birds of prey, falcons and owls). In this study, concentrations of eight bisphenols and five benzophenone UV filters were determined in six raptor tissues, including muscle, kidney, liver, brain, preen gland (uropygial gland) and adipose. The tissue samples (n = 44) were taken from dead raptor species (1997-2011), including Eurasian sparrowhawks (Accipiter nisus, n = 2) and long-eared owls (Asio otus, n = 2), both from France, and white-tailed eagles (Haliaeetus albicilla, n = 16) from Greenland. Overall, six bisphenols and four benzophenone UV filters were found in the samples. Bisphenol A (BPA), bisphenol F (BPF), benzophenone-8 (BzP-8) and 4-hydroxybenzophenone (4-OH-BzP) were the most abundant contaminants, accounting for median concentrations of 67.5, 3.01, 27.1 and 9.70 ng/g wet weight (w.w.), respectively. The potential role of the preen gland as a major excretory organ for bisphenols and benzophenone UV filters was suggested since the median sum concentration of the two contaminant classes in the white-tailed eagle tissues showed higher bioaccumulation potential in the preen gland (5.86 ng/g w.w.) than the liver (2.92) and kidney (0.71). The concentrations of these contaminants in the tissues of the three raptor species indicated a pattern of increasing detection rates and median concentrations with an increase of the species size and their expected trophic position. To the best of our knowledge, this is the first peer-reviewed study to document multiresidues of both contaminant classes in raptor tissues., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Bone is remodelled constantly through a balance of bone formation and resorption. This process can be affected by various factors such as hormones, vitamins, nutrients and environmental factors, which can create an imbalance resulting in systemic or local bone alteration. The aim of the present study was to analyse the changes in bone mineral density (BMD) over time in skulls of ringed seals (Pusa hispida) from the Baltic and Greenland using museum samples. Overall, 303 skulls (102 Male, 89 Female, 112 unknown) were used for bone investigations and were divided into three periods according to collection year: before 1958 (n = 167), between 1958 and 1989 (n = 40) and after 1994 up to 2019 (n = 96). All skulls were examined by dual-energy X-ray absorptiometry to obtain the BMD. Skull BMD of the Baltic seals was positively correlated with the historical polychlorinated biphenyls (PCB) contamination having potential effects on the constitution of bones. BMD fluctuated between the three study periods (LM: p-value < 0.001, F-value = 47.5) with the lowest BMD found between 1897 and 1957, in the Gulf of Bothnia, where the highest peak of contaminant concentration was in the second period. BMD levels increased with increasing PCB concentration (LM: p < 0.001). The Greenland population showed significant lower BMD levels in the pollution and post-pollution period than the Baltic population (LM: p < 0.001). It also revealed a higher BMD in males than in females (LM: p = 0.03). In conclusion, the variations between 1829 and 2019 in the Baltic Sea and Greenland may to a certain extent reflect normal fluctuations; however, this study revealed several factors affecting BMD, including sex and PCB levels., (Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Although sled dogs are one of the most specialized groups of dogs, their origin and evolution has received much less attention than many other dog groups. We applied a genomic approach to investigate their spatiotemporal emergence by sequencing the genomes of 10 modern Greenland sled dogs, an ~9500-year-old Siberian dog associated with archaeological evidence for sled technology, and an ~33,000-year-old Siberian wolf. We found noteworthy genetic similarity between the ancient dog and modern sled dogs. We detected gene flow from Pleistocene Siberian wolves, but not modern American wolves, to present-day sled dogs. The results indicate that the major ancestry of modern sled dogs traces back to Siberia, where sled dog-specific haplotypes of genes that potentially relate to Arctic adaptation were established by 9500 years ago., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Understanding the spatiotemporal patterns of legacy organochlorines (OCs) is often difficult because monitoring practices differ among studies, fragmented study periods, and unaccounted confounding by ecological variables. We therefore reconstructed long-term (1939-2015) and large-scale (West Greenland, Norway, and central Sweden) trends of major legacy OCs using white-tailed eagle (Haliaeetus albicilla) body feathers, to understand the exposure dynamics in regions with different contamination sources and concentrations, as well as the effectiveness of legislations. We included dietary proxies (δ 13 C and δ 15 N) in temporal trend models to control for potential dietary plasticity. Consistent with the hypothesised high local pollution sources, levels of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) in the Swedish subpopulation exceeded those in the other subpopulations. In contrast, chlordanes (CHLs) and hexachlorobenzene (HCB) showed higher concentrations in Greenland, suggesting the importance of long-range transport. The models showed significantly decreasing trends for all OCs in Sweden in 1968-2011 except for CHLs, which only decreased since the 1980s. Nevertheless, median concentrations of DDTs and PCBs remained elevated in the Swedish subpopulation throughout the 1970s, suggesting that the decreases only commenced after the implementation of regulations during the 1970s. We observed significant trends of increasing concentrations of PCBs, CHLs and HCB in Norway from the 1930s to the 1970s/1980s and decreasing concentrations thereafter. All OC concentrations, except those of PCBs were generally significantly decreasing in the Greenland subpopulation in 1985-2013. All three subpopulations showed generally increasing proportions of the more persistent compounds (CB 153, p.p'-DDE and β-HCH) and decreasing proportions of the less persistent ones (CB 52, p.p'-DDT, α- and γ-HCH). Declining trends of OC concentrations may imply the decreasing influence of legacy OCs in these subpopulations. Finally, our results demonstrate the usefulness of archived museum feathers in retrospective monitoring of spatiotemporal trends of legacy OCs using birds of prey as sentinels., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

There is increasing evidence that the ∼20 routinely monitored perfluoroalkyl and polyfluoroalkyl substances (PFASs) account for only a fraction of extractable organofluorine (EOF) occurring in the environment. To assess whether PFAS exposure is being underestimated in marine mammals from the Northern Hemisphere, we performed a fluorine mass balance on liver tissues from 11 different species using a combination of targeted PFAS analysis, EOF and total fluorine determination, and suspect screening. Samples were obtained from the east coast United States (US), west and east coast of Greenland, Iceland, and Sweden from 2000 to 2017. Of the 36 target PFASs, perfluorooctane sulfonate (PFOS) dominated in all but one Icelandic and three US samples, where the 7:3 fluorotelomer carboxylic acid (7:3 FTCA) was prevalent. This is the first report of 7:3 FTCA in polar bears (∼1000 ng/g, ww) and cetaceans (<6-190 ng/g, ww). In 18 out of 25 samples, EOF was not significantly greater than fluorine concentrations derived from sum target PFASs. For the remaining 7 samples (mostly from the US east coast), 30-75% of the EOF was unidentified. Suspect screening revealed an additional 37 PFASs (not included in the targeted analysis) bringing the total to 63 detected PFASs from 12 different classes. Overall, these results highlight the importance of a multiplatform approach for accurately characterizing PFAS exposure in marine mammals.

Domestic dogs have been central to life in the North American Arctic for millennia. The ancestors of the Inuit were the first to introduce the widespread usage of dog sledge transportation technology to the Americas, but whether the Inuit adopted local Palaeo-Inuit dogs or introduced a new dog population to the region remains unknown. To test these hypotheses, we generated mitochondrial DNA and geometric morphometric data of skull and dental elements from a total of 922 North American Arctic dogs and wolves spanning over 4500 years. Our analyses revealed that dogs from Inuit sites dating from 2000 BP possess morphological and genetic signatures that distinguish them from earlier Palaeo-Inuit dogs, and identified a novel mitochondrial clade in eastern Siberia and Alaska. The genetic legacy of these Inuit dogs survives today in modern Arctic sledge dogs despite phenotypic differences between archaeological and modern Arctic dogs. Together, our data reveal that Inuit dogs derive from a secondary pre-contact migration of dogs distinct from Palaeo-Inuit dogs, and probably aided the Inuit expansion across the North American Arctic beginning around 1000 BP.

We reconstructed the first long-term (1968-2015) spatiotemporal trends of perfluoroalkyl substances (PFAS) using archived body feathers of white-tailed eagles ( Haliaeetus albicilla ) from the West Greenland ( n = 31), Norwegian ( n = 66), and Central Swedish Baltic coasts ( n = 50). We observed significant temporal trends of perfluorooctane sulfonamide (FOSA), perfluorooctane sulfonate (PFOS), and perfluoroalkyl carboxylates (∑PFCAs) in all three subpopulations. Concentrations of FOSA and PFOS had started decreasing significantly since the mid-1990s to 2000 in the Greenland and Norwegian subpopulations, consistent with the 3M phase-out, though in sharp contrast to overall increasing trends observed in the Swedish subpopulation. Moreover, ∑PFCA concentrations significantly increased in all three subpopulations throughout the study periods. These temporal trends suggest on-going input of PFOS in the Baltic and of ∑PFCAs in all three regions. Considerable spatial variation in PFAS concentrations and profiles was observed: PFOS concentrations were significantly higher in Sweden, whereas FOSA and ∑PFCA concentrations were similar among the subpopulations. PFOS dominated the PFAS profiles in the Swedish and Norwegian subpopulations, in contrast to the domination of FOSA and ∑PFCAs in the Greenland one. Our spatiotemporal observations underline the usefulness of archived bird of prey feathers in monitoring spatiotemporal PFAS trends and urge for continued monitoring efforts in each of the studied subpopulations.

The spatiotemporal trends of mercury (Hg) are crucial for the understanding of this ubiquitous and toxic contaminant. However, uncertainties often arise from comparison among studies using different species, analytical and statistical methods. The long-term temporal trends of Hg exposure were reconstructed for a key sentinel species, the white-tailed eagle (Haliaeetus albicilla). Body feathers were sampled from museum collections covering 150 years in time (from 1866 to 2015) from West Greenland (n = 124), Norway (n = 102), and Sweden (n = 87). A significant non-linear trend was observed in the Norwegian subpopulation, with a 60% increase in exposure occurring from 1866 to 1957 followed by a 40% decline until 2015. In the Swedish subpopulation, studied at a later period, the Hg exposure showed a drastic decline of 70% from 1967 to 2011. In contrast, no significant trend could be observed in the Greenland subpopulation. The additional analysis of dietary proxies (δ 13 C and δ 15 N) in general increased performance of the temporal trend models, but this was dependent on the subpopulation and study period. The downward trend of Hg coincided with the decreasing δ 13 C and δ 15 N in the Norwegian subpopulation, suggesting a potential dietary mitigation of Hg contamination. Hg exposure in both the Greenland and Norwegian subpopulations was consistently below the suggested threshold for adverse health effects (40.0 μg g -1 ), while the maximum exposure in the Swedish subpopulation was distinctively elevated (median: 46.0 μg g -1 ) and still remains well above natural background concentrations (maximum 5.0 μg g -1 )., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The bioaccumulation and biomagnification of 22 major perfluoroalkyl substances (PFAS) were investigated in tissues of polar bears (Ursus maritimus) and their major prey species, the ringed seal (Pusa hispida), from the Scoresby Sound region of East Greenland. In polar bear liver the mean Σ 4 PFSA (perfluoroalkyl sulfonic acid) concentration (C 4 , C 6 , C 8 and C 10 ) was 2611 ± 202 ng/g wet weight (ww; 99% perfluorooctane sulfonate (PFOS)) and two orders of magnitude higher than the 20 ± 3 ng/g ww (89% PFOS) concentration in fat. The mean Σ 4 PFSAs in seal liver was 111 ± 5 ng/g ww (98% PFOS) and three orders of magnitude higher relative to the 0.05 ± 0.01 ng/g ww concentration in blubber (100% perfluorohexane sulfonate). Perfluoro-1-octane sulfonamide (FOSA) was quantifiable in bear (mean 10 ± 1.4 ng/g ww) and seal (mean 0.6 ± 0.1 ng/g ww) liver but not in fat or blubber. The mean Σ 13 PFCAs (C 4 -C 18 ; perfluoroalkyl carboxylic acids) in bear liver (924 ± 71 ng/g ww) was much greater than in seal liver (74 ± 6 ng/g ww). In bear fat and seal blubber, the mean Σ 13 PFCAs were 15 ± 1.9 and 0.9 ± 0.1 ng/g ww, respectively. Longer chain C 11 to C 14 PFCAs dominated in bear fat and seal blubber (60-80% of Σ 13 PFCA), whereas shorter-chain C 9 to C 11 PFCAs dominated in the liver (85-90% of Σ 13 PFCA). Biomagnification factors (BMFs) were orders of magnitude greater for PFHxS and C 9 to C 13 PFCAs when based on bear liver to seal blubber rather than bear liver to seal liver, and PFCA (C 9 to C 13 ) BMFs decreased with increasing chain length. Seal blubber to bear liver BMFs better reflects the dietary exposure relationship of PFAS between bears and seals., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Persistent organic pollutants (POPs) are found in high concentrations in the Artic. Polar bears (Ursus maritimus) are one of the most exposed mammals in the Arctic and are thereby vulnerable to reproductive disruption. The aim of this study was to investigate male polar bear reproduction based on a detailed evaluation of testis histology and to assess possible effects of environmental chemicals on male polar bear reproduction. Reproductive groups that were identified based on histology were as follows: actively reproductive (REP), non-reproductive either with degenerated testes (DEG), undeveloped seminiferous tubules (UND), or morphology in-transition (INT). Categorization into these groups was supported by significant differences in testis and baculum measurements among REP, DEG, and UND, as well as differences in the area and diameter of seminiferous tubules among REP, DEG, and UND. These results show that it is possible to identify the reproductive stage in polar bears even if capture date and or age is lacking. Based on testis morphology we suggest that adult male polar bears from East Greenland have active spermatogenesis in February to June, and inactive degenerated testes in August to January. January to February was the main period of reproductive transition, characterised by a shift between inactive and active spermatogenesis. Baculum and testis size measurements decreased significantly with increasing concentrations of the chlordane metabolite oxychlordane, suggesting a potential impact on male reproductive success. Half of the investigated polar bears in REP group displayed signs of disorganization of the spermatogenesis which might be a sign of disrupted reproduction. However, no correlations with levels of the investigated POPs were detected. Reproductive organ measurements in polar bears differed significantly between REP and DEG groups, which cannot be explained by age, and therefore should be considered when investigating the effect of POPs on male reproduction., (Copyright © 2019. Published by Elsevier Inc.)

We investigated skull size (condylobasal length; CBL) and bone mineral density (BMD) in polar bears (Ursus maritimus) from East Greenland (n = 307) and Svalbard (n = 173) sampled during the period 1892-2015 in East Greenland and 1964-2004 at Svalbard. Adult males from East Greenland showed a continuous decrease in BMD from 1892 to 2015 (linear regression: p < 0.01) indicating that adult male skulls collected in the early pre-pollution period had the highest BMD. A similar decrease in BMD over time was not found for the East Greenland adult females. However, there was a non-significant trend that the skull size of adult East Greenland females was negatively correlated with collection year 1892-2015 (linear regression: p = 0.06). No temporal change was found for BMD or skull size in Svalbard polar bears (ANOVA: all p > 0.05) nor was there any significant difference in BMD between Svalbard and East Greenland subpopulations. Skull size was larger in polar bears from Svalbard than from East Greenland (two-way ANOVA: p = 0.003). T-scores reflecting risk of osteoporosis showed that adult males from both East Greenland and Svalbard are at risk of developing osteopenia. Finally, when correcting for age and sex, BMD in East Greenland polar bears increased with increasing concentrations of persistent organic pollutants (POPs) i.e. ΣPCB (polychlorinated biphenyls), ΣHCH (hexachlorohexane), HCB (hexachlorobenzene) and ΣPBDE (polybrominated diphenyl ethers) while skull size increased with ΣHCH concentrations all in the period 1999-2014 (multiple linear regression: all p < 0.05, n = 175). The results suggest that environmental changes over time, including exposure to POPs, may affect bone density and size of polar bears., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Narwhals (Monodon monoceros) are at the top of the Arctic food web and therefore might biomagnify high total mercury (Hg) concentrations in organs and tissues. The aim of this study was to determine histopathology and Hg concentrations in liver and kidneys from 15 North East Greenland narwhals (3 subadult females, 8 adult females, 3 subadult males, and 1 adult male) and compare data with previous observations of 12 North West Greenland specimens (1 subadult female, 4 adult females, 1 subadult male, and 6 adult males). The zoological length was significantly larger and hepatic and renal concentrations significantly higher in adults compared to subadults. When comparing tissues, the Hg levels were significantly the highest in liver, while a correlation between metal levels in liver and kidneys was positive and significant. Histological examination of renal tissues presented four types of glomerular lesions (capillary dilatation [0-100%], membrane thickening [0-100%], dilatation of space [0-80%], and sclerosis [0-70%]) and two tubular lesions (atrophy/hyalinization [0-40%] and casts [0-60%]). Hepatic tissues exhibited three portal lesions (fibrosis [0-33%], cell infiltrates [0-40%], and bile duct proliferation [0-40%]) and two parenchymal lesions (steatosis [83-100%] and lipid-filled Ito cells [0-33%]). All 12 lesions were found in adult whales from North West Greenland while eight were present in adult whales from North East Greenland. Six lesions were detected in subadults from North East Greenland and four in subadults from North West Greenland. A significantly higher frequency of dilatation and hyalinization of Bowman's space and capsule and glomerular capillary dilatation was found in adult narwhals from West Greenland. There was no marked difference in Hg concentrations in whales with and without histological lesions. In conclusion, the prevalence of histological changes and Hg levels were the highest in adults and therefore both age and metal are important factors to include when evaluating liver and kidney lesions in narwhals.

We used PBPK (physiologically-based pharmacokinetic) modelling to investigate distribution, bioaccumulation and excretion of the seven POPs (persistent organic pollutants) CB-99, CB-153, HCB, oxychlordane, p,p'-DDE, BDE-47 and BDE-99 in 4 adult captive Greenland sledge dog (Canis familiaris) bitches fed minke whale (Balaenoptera acuterostrata) blubber for 500-635 days. The PBPK modelled POP concentrations in adipose tissue, liver, kidney and plasma were mostly within a factor 2 of actual measured tissue levels even for those at the lower concentration end. The excretion route for oxychlordane and CB-153 was modelled to be via faeces while lung alveolar excretion dominated for BDE-47, BDE-99, HCB, p,p'-DDE and CB-99. Furthermore the model suggested the retained mass of POPs after 500 and 635 days of exposure, respectively, to be relatively low despite these POPs being highly recalcitrant. The retention increased in the following order (% of total intake); p,p'-DDE (1%)

Perfluoroalkyl substances (PFASs) is a growing class of contaminants in the Arctic environment, and include the established perfluorinated sulfonates (PFSAs; especially perfluorooctane sulfonate (PFOS)) and carboxylic acids (PFCAs). PFSAs and PFCAs of varying chain length have been reported to bioaccumulate in lipid rich tissues of the brain among other tissues such as liver, and can reach high concentrations in top predators including the polar bear. PFCA and PFSA bioaccummulation in the brain has the potential to pose neurotoxic effects and therefore we conducted a study to investigate if variations in neurochemical transmitter systems i.e. the cholinergic, glutaminergic, dopaminergic and GABAergic, could be related to brain-specific bioaccumulation of PFASs in East Greenland polar bears. Nine brain regions from nine polar bears were analyzed for enzyme activity (monoamine oxidase (MAO), acetylcholinesterase (AChE) and glutamine synthetase (GS)) and receptor density (dopamine-2 (D2), muscarinic cholinergic (mAChR) and gamma-butyric acid type A (GABA-A)) along with PFSA and PFCA concentrations. Average brain ∑PFSA concentration was 25ng/g ww where PFOS accounted for 91%. Average ∑PFCA concentration was 88ng/g ww where PFUnDA, PFDoDA and PFTrDA combined accounted for 79%. The highest concentrations of PFASs were measured in brain stem, cerebellum and hippocampus. Correlative analyses were performed both across and within brain regions. Significant positive correlations were found between PFASs and MAO activity in occipital lobe (e.g. ∑PFCA; rp=0.83, p=0.041, n=6) and across brain regions (e.g. ∑PFCA; rp=0.47, p=0.001, ∑PFSA; rp=0.44, p>0.001; n=50). GABA-A receptor density was positively correlated with two PFASs across brain regions (PFOS; rp=0.33, p=0.02 and PFDoDA; rp=0.34, p=0.014; n=52). Significant negative correlations were found between mAChR density and PFASs in cerebellum (e.g. ∑PFCA; rp=-0.95, p=0.013, n=5) and across brain regions (e.g. ∑PFCA; rp=-0.40, p=0.003, ∑PFSA; rp=-0.37, p=0.007; n=52). AChE activity and D2 density were negatively correlated with single PFCAs in several brain regions, whereas GS activity was positively correlated with PFASs primarily in occipital lobe. Results from the present study support the hypothesis that PFAS concentrations in polar bears from East Greenland have exceeded the threshold limits for neurochemical alterations. It is not known whether the observed alterations in neurochemical signaling are currently having negative effects on neurochemistry in East Greenland polar bears. However given the importance of these systems in cognitive processes and motor function, the present results indicate an urgent need for a better understanding of neurochemical effects of PFAS exposure to wildlife., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Industrially produced chemicals have been a major environmental concern across our entire Globe since the onset of rapid industrial development around the early 1900. Many of the substances being used are known to be endocrine disrupting chemicals (EDCs) and are also known to be long-range dispersed and to biomagnify to very high concentrations in the tissues of Arctic apex predators such as polar bears (Ursus maritimus). A major concern relating to EDCs is their effects on vital organ-tissues such as bone and it is possible that EDCs represent a more serious challenge to the species' survival than the more conventionally proposed prey reductions linked to climate change. We therefore analyzed penile bone mineral density (BMD) as a key phenotype for reproductive success in 279 polar bear samples born 1990-2000 representing eight polar bear subpopulations. Since EDC concentrations were not available from the same specimens, we compared BMD with published literature information on EDC concentrations. Latitudinal and longitudinal BMD and EDC gradients were clearly observed, with Western Hudson bears having the highest BMD and lowest EDCs, and North East Greenland polar bears carrying the lowest BMD and highest EDCs. A BMD vs. polychlorinated biphenyls (PCB) regression analysis showed that BMD decreased as a function of the eight subpopulations' PCB concentrations and this relationship was close to being significant (p=0.10, R(2)=0.39). Risk quotient (RQ) estimation demonstrated that PCBs could be in a range that may lead to disruption of normal reproduction and development. It is therefore likely that EDCs directly affect development and bone density in polar bears. Canadian bears had in general the best health and the North East Greenland subpopulation being at the highest risk of having negative health effects. While reductions in BMD is in general unhealthy, reductions in penile BMD could lead to increased risk of species extinction because of mating and subsequent fertilization failure as a result of weak penile bones and risk of fractures. Based on this, future studies should assess how polar bear subpopulations respond upon EDC exposure since information and understanding about their circumpolar reproductive health is vital for future conservation., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Previous studies have shown relationships between organohalogen contaminants (OHCs) and circulating levels of thyroid hormones (THs) in arctic wildlife. However, there is a lack of knowledge concerning the possible functional effects of OHCs on TH status in target tissues for TH-dependent activity. The relationships between circulating (plasma) levels of OHCs and various TH variables in plasma as well as in liver, muscle and kidney tissues from East Greenland sub-adult polar bears (Ursus maritimus) sampled in 2011 (n=7) were therefore investigated. The TH variables included 3.3',5.5'-tetraiodothyronine or thyroxine (T4), 3.3',5-triiodothyronine (T3) and type 1 (D1) and type 2 (D2) deiodinase activities. Principal component analysis (PCA) combined with correlation analyses demonstrated negative relationships between individual polychlorinated biphenyls (PCBs) and their hydroxylated (OH-) metabolites and T4 in both plasma and muscle. There were both positive and negative relationships between individual OHCs and D1 and D2 activities in muscle, liver and kidney tissues. In general, PCBs, OH-PCBs and polybrominated dipehenyl ethers (PBDEs) were positively correlated to D1 and D2 activities, whereas organochlorine pesticides and byproducts (OCPs) were negatively associated with D1 and D2 activities. These results support the hypothesis that OHCs can affect TH status and action in the target tissues of polar bears. TH levels and deiodinase activities in target tissues can be sensitive endpoints for exposure of TH-disrupting compounds in arctic wildlife, and thus, tissue-specific responses in target organs should be further considered when assessing TH disruption in wildlife studies., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Climate change will increasingly affect the natural habitat and diet of polar bears (Ursus maritimus). Understanding the energetic needs of polar bears is therefore important. We developed a theoretical method for estimating polar bear food consumption based on using the highly recalcitrant polychlorinated biphenyl (PCB) congener, 2,2',4,4',55-hexaCB (CB153) in bear adipose tissue as an indicator of food intake. By comparing the CB153 tissue concentrations in wild polar bears with estimates from a purposely designed individual-based model, we identified the possible combinations of field metabolic rates (FMR) and CB153 deposition efficiencies in East Greenland polar bears. Our simulations indicate that if 30% of the CB153 consumed by polar bear individuals were deposited into their adipose tissue, the corresponding FMR would be only two times the basal metabolic rate. In contrast, if the modelled CB153 deposition efficiency were 10%, adult polar bears would require six times more energy than that needed to cover basal metabolism. This is considerably higher than what has been assumed for polar bears in previous studies though it is similar to FMRs found in other marine mammals. An implication of this result is that even relatively small reductions in future feeding opportunities could impact the survival of East Greenland polar bears.

This paper studied the levels and organ distribution of the toxic heavy metal cadmium in scallops from unpolluted Greenlandic waters. The scallops had an average cadmium concentration of 2.93 ± 0.94 μg/g wet weight in the total soft tissues and no concentration dependent effect was found for gender or size (both p>0.05). The kidney was the primary organ for cadmium accumulation with a mean of 226.2 ± 111.7 μg/g wet weight, and despite the small weight of the kidney, it appeared as the principal contributor of cadmium with 92% of the total cadmium body burden. The cadmium concentrations in the total soft tissues far exceeded the EU-limit of 1 μg/g wet weight for cadmium in bivalves. Based on this, selective evisceration of the cadmium-rich kidney and digestive gland during processing can be regarded as a reliable measure to be taken in order to reduce the cadmium content of scallops used for human consumption., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The former Black Angel lead-zinc mine in Maarmorilik, West Greenland, is a historic example of how mining activity may result in a significant impact on the surrounding fjord system in terms of elevated concentrations of especially lead (Pb) and zinc (Zn) in seawater, sediments and surrounding biota. In order to shed light on the present contamination and possible effects in the fjord we initiated a range of studies including a pilot study on gill and liver morphology of common sculpins (Myoxocephalus scorpius) around Maarmorilik. Sculpins were caught and sampled at five different stations known to represent a gradient of Pb concentrations. Fish livers from all specimens were analyzed for relevant elements in the area: Fe, Zn, As, Cu, Se, Cd, Pb, Ag, Hg, Co and Ni. Lead, As and Hg showed significant differences among the five stations. For 20% of the sculpins, Hg concentrations were in the range of lowest observed effect dose (LOED) of 0.1-0.5 μg/g ww for toxic threshold on reproduction and subclinical endpoints. Likewise LOEDs for tissue lesions, LOEDs for biochemistry, growth, survival and reproduction were exceeded for Cd (0.42-1.8 μg/g ww) and for As (11.6 μg/g ww) in 28% and 85% of the sculpins, respectively. Similar to this, the no observed effect dose (NOED) for biochemistry was exceeded for Pb (0.32 μg/g ww) and for growth, mortality and reproduction for Zn (60-68 μg/g ww) in 33% and 24% of the sculpins, respectively. For all sculpins, females were significantly larger than males and for five of the elements (Fe, Co, Ni, Cu, Se) females had higher concentrations. The chronic lesions observed in liver (mononuclear cell infiltrates, necrosis, vacuolar hepatocytes, portal fibrosis, bile duct hyperplasia, active melanomacrophage centers) and gills (fusion and edema of secondary lamellae, laminar telangiectasis, mononuclear cell infiltrates, blebs) were similar to those in the literature studies for both wild and laboratory exposed sculpins and other fish species carrying similar or higher Hg concentrations. Ignoring sex and size, specimens with hepatic cell infiltrates had the highest concentrations of most elements, a relation that was also found for gill telangiectasis and Hg (all p < 0.05). When controlling for sex and size, the prevalence of vacuolar hepatocytes and endoparasites was significantly highest at the three most contaminated stations and similar differences were found for liver necrosis. We suggest that beside exposure to mining-related elements, other environmental factors, such as parasites, might be co-factors in the development of the observed liver and gill lesions. Therefore, sculpin liver and gill pathology are likely to be suitable health indicators when biomonitoring gradients of mining and other element related activity effects; while a larger study is required to fully evaluate the relationships., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Time-series of perfluorinated alkylated substances (PFASs) in East Greenland polar bears and East and West Greenland ringed seals were updated in order to deduce whether a response to the major reduction in perfluoroalkyl production in the early 2000s had occurred. Previous studies had documented an exponential increase of perfluorooctane sulphonate (PFOS) in liver tissue from both species. In the present study, PFOS was still the far most dominant compound constituting 92% (West Greenland ringed seals), 88% (East Greenland ringed seals) and 85% (East Greenland polar bears). The PFOS concentrations increased up to 2006 with doubling times of approximately 6 years for the ringed seal populations and 14 years in case of polar bears. Since then a rapid decrease has occurred with clearing half-lives of approximately 1, 2 and 4 years, respectively. In polar bears perfluorohexane sulphonate (PFHxS) and perfluorooctane sulphonamide (PFOSA) also showed decreasing trends in recent years as do perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnA). For the West Greenland ringed seal population perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), PFDA and PFUnA peaked in the mid 2000s, whereas PFNA, PFDA and PFUnA in the East Greenland population have been stable or increasing in recent years. The peak of PFASs in Greenland ringed seals and polar bears occurred at a later time than in Canadian seals and polar bears and considerably later than observed in seal species from more southern latitudes. We suggest that this could be explained by the distance to emission hot-spots and differences in long-range transport to the Arctic., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Traditionally it has been difficult or impossible to collect and preserve bacterial samples of especially fastidious bacteria in mixed primary cultures, unless the samples could be transported to a laboratory within approximately 24 h. Therefore, a simple novel method for preserving swab samples until bacterial isolation can be completed in the laboratory was developed and evaluated. Pasteurellaceae bacteria were used as a representative for fastidious bacteria. A 7.5% glucose serum medium was used as freeze medium. Swab samples were soaked in the medium a maximum of 2 h after collection and stored at -20°C. As a control study, 15 samples were collected from the oral cavity of a captive brown bear. One was immediately plated, while the remaining 12 swabs were stored at -20°C for 7 days and multiples of 30 days up to 330 days prior to plating. Two samples were stored without the medium for 7 and 30 days prior to plating. From a field setting in Greenland, eight polar bear samples were collected and subsequently stored for 240 to 259 days at -20°C before incubation. Pasteurellaceae bacteria were isolated and genotyped from all samples stored in the freeze medium, indicating that the medium enabled the bacteria to survive for at least 330 days at -20°C. The 100% recovery of target organisms in the polar bear samples even following lengthy storage and transport demonstrates that the method is very useful under remote field conditions., (© 2013 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.)

Intraspecific differences in movement behaviour reflect different tactics used by individuals or sexes to favour strategies that maximize fitness. We report movement data collected from n = 23 adult male polar bears with novel ear-attached transmitters in two separate pack ice subpopulations over five breeding seasons. We compared movements with n = 26 concurrently tagged adult females, and analysed velocities, movement tortuosity, range sizes and habitat selection with respect to sex, reproductive status and body mass. There were no differences in 4-day displacements or sea ice habitat selection for sex or population. By contrast, adult females in all years and both populations had significantly more linear movements and significantly larger breeding range sizes than males. We hypothesized that differences were related to encounter rates, and used observed movement metrics to parametrize a simulation model of male-male and male-female encounter. The simulation showed that the more tortuous movement of males leads to significantly longer times to male-male encounter, while having little impact on male-female encounter. By contrast, linear movements of females are consistent with a prioritized search for sparsely distributed prey. These results suggest a possible mechanism for explaining the smaller breeding range sizes of some solitary male carnivores compared to females.

Temporal trends of mercury in livers of ringed seals collected from the early 1980s to 2010 from central West, Northwest and central East Greenland were studied. In this period the climate of Greenland warmed and the influences of climate indices such as ice coverage, water temperature and the Atlantic Oscillation Index on mercury concentration were evaluated using multiple regressions and Akaike's Information Criteria (AIC) to determine the most parsimonious models. Biological co-variables such as age, sex and trophic position (as determined by stable isotope analysis) of seals were also evaluated. Increasing levels of mercury in seals were found in Ittoqqortoormiit, central East Greenland, and Avanersuaq, Northwest Greenland, with an annual increase of +10.3 and +2%, respectively. Age was an important co-variable for all three regions and trophic position for two regions. The Atlantic Oscillation Index was also an important explanatory variable for all three regions and was positively associated with mercury concentrations in seals indicating the importance of global climatic processes on ringed seal populations in Greenland.

Several perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs) of varying chain length are bioaccumulative in biota. However, wildlife reports have focused on liver and with very little examination of other tissues, and thus there is a limited understanding of their distribution and potential effects in the mammalian body. In the present study, the comparative accumulation of C(6) to C(15) PFCAs, C(4), C(6), C(8) and C(10) PFSAs, and select precursors were examined in the liver, blood, muscle, adipose, and brain of 20 polar bears (Ursus maritimus) from Scoresby Sound, Central East Greenland. Overall, PFSA and PFCA concentrations were highest in liver followed by blood > brain > muscle ≈ adipose. Liver and blood samples contained proportionally more of the shorter/medium chain length (C(6) to C(11)) PFCAs, whereas adipose and brain samples were dominated by longer chain (C(13) to C(15)) PFCAs. PFCAs with lower lipophilicities accumulated more in the liver, whereas the brain accumulated PFCAs with higher lipophilicities. The concentration ratios (±SE) between perfluorooctane sulfonate and its precursor perfluorooctane sulfonamide varied among tissues from 9 (±1):1 (muscle) to 36 (±7):1 (liver). PFCA and PFSA patterns in polar bears indicate that the pharmacokinetics of these compounds are to some extent tissue-specific, and are the result of several factors that may include differing protein interactions throughout the body.

Spatial trends and comparative changes in time of selected trace elements were studied in liver tissue from polar bears from ten different subpopulation locations in Alaska, Canadian Arctic and East Greenland. For nine of the trace elements (As, Cd, Cu, Hg, Mn, Pb, Rb, Se and Zn) spatial trends were investigated in 136 specimens sampled during 2005-2008 from bears from these ten subpopulations. Concentrations of Hg, Se and As were highest in the (northern and southern) Beaufort Sea area and lowest in (western and southern) Hudson Bay area and Chukchi/Bering Sea. In contrast, concentrations of Cd showed an increasing trend from east to west. Minor or no spatial trends were observed for Cu, Mn, Rb and Zn. Spatial trends were in agreement with previous studies, possibly explained by natural phenomena. To assess temporal changes of Cd, Hg, Se and Zn concentrations during the last decades, we compared our results to previously published data. These time comparisons suggested recent Hg increase in East Greenland polar bears. This may be related to Hg emissions and/or climate-induced changes in Hg cycles or changes in the polar bear food web related to global warming. Also, Hg:Se molar ratio has increased in East Greenland polar bears, which suggests there may be an increased risk for Hg(2+)-mediated toxicity. Since the underlying reasons for spatial trends or changes in time of trace elements in the Arctic are still largely unknown, future studies should focus on the role of changing climate and trace metal emissions on geographical and temporal trends of trace elements.

We investigated the multivariate relationships between adipose tissue residue levels of 48 individual organohalogen contaminants (OHCs) and circulating thyroid hormone (TH) levels in polar bears (Ursus maritimus) from East Greenland (1999-2001, n=62), using projection to latent structure (PLS) regression for four groupings of polar bears; subadults (SubA), adult females with cubs (AdF&#95;N), adult females without cubs (AdF&#95;S) and adult males (AdM). In the resulting significant PLS models for SubA, AdF&#95;N and AdF&#95;S, some OHCs were especially important in explaining variations in circulating TH levels: polybrominated diphenylether (PBDE)-99, PBDE-100, PBDE-153, polychlorinated biphenyl (PCB)-52, PCB-118, cis-nonachlor, trans-nonachlor, trichlorobenzene (TCB) and pentachlorobenzene (QCB), and both negative and positive relationships with THs were found. In addition, the models revealed that DDTs had a positive influence on total 3,5,3'-triiodothyronine (TT3) in AdF&#95;S, and that a group of 17 higher chlorinated ortho-PCBs had a positive influence on total 3,5,3',5'-tetraiodothyronine (thyroxine, TT4) in AdF&#95;N. TH levels in AdM seemed less influenced by OHCs because of non-significant PLS models. TH levels were also influenced by biological factors such as age, sex, body size, lipid content of adipose tissue and sampling date. When controlling for biological variables, the major relationships from the PLS models for SubA, AdF&#95;N and AdF&#95;S were found significant in partial correlations. The most important OHCs that influenced TH levels in the significant PLS models may potentially act through similar mechanisms on the hypothalamic-pituitary-thyroid (HPT) axis, suggesting that both combined effects by dose and response addition and perhaps synergistic potentiation may be a possibility in these polar bears. Statistical associations are not evidence per se of biological cause-effect relationships. Still, the results of the present study indicate that OHCs may affect circulating TH levels in East Greenland polar bears, adding to the "weight of evidence" suggesting that OHCs might interfere with thyroid homeostasis in polar bears., (Copyright © 2011 Elsevier Ltd. All rights reserved.)