Genomic diversity and differentiation between island and mainland populations of white-tailed eagles (Haliaeetus albicilla).

Divergence in the face of high dispersal capabilities is a documented but poorly understood phenomenon. The white-tailed eagle (Haliaeetus albicilla) has a large geographic dispersal capability and should theoretically be able to maintain genetic homogeneity across its dispersal range. However, following analysis of the genomic variation of white-tailed eagles, from both historical and contemporary samples, clear signatures of ancient biogeographic substructure across Europe and the North-East Atlantic is observed. The greatest genomic differentiation was observed between island (Greenland and Iceland) and mainland (Denmark, Norway and Estonia) populations. The two island populations share a common ancestry from a single mainland population, distinct from the other sampled mainland populations, and despite the potential for high connectivity between Iceland and Greenland they are well separated from each other and are characterized by inbreeding and little variation. Temporal differences also highlight a pattern of regional populations persisting despite the potential for admixture. All sampled populations generally showed a decline in effective population size over time, which may have been shaped by four historical events: (1) Isolation of refugia during the last glacial period 110-115,000 years ago, (2) population divergence following the colonization of the deglaciated areas ~10,000 years ago, (3) human population expansion, which led to the settlement in Iceland ~1100 years ago, and (4) human persecution and exposure to toxic pollutants during the last two centuries.

A retrospective investigation of feather corticosterone in a highly contaminated white-tailed eagle (Haliaeetus albicilla) population.

Exposure to persistent organic pollutants (POPs), such as organochlorines (OCs) and polybrominated diphenyl ethers (PBDEs), is associated with adverse health effects in wildlife. Many POPs have been banned and consequently their environmental concentrations have declined. To assess both temporal trends of POPs and their detrimental impacts, raptors are extensively used as biomonitors due to their high food web position and high contaminant levels. White-tailed eagles (WTEs; Haliaeetus albicilla) in the Baltic ecosystem represent a sentinel species of environmental pollution, as they have suffered population declines due to reproductive failure caused by severe exposure to dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCB) during the 1960s through 1980s. However, there is a lack of long-term studies that cover a wide range of environmental contaminants and their effects at the individual level. In this study, we used 135 pooled samples of shed body feathers collected in 1968-2012 from breeding WTE pairs in Sweden. Feathers constitute a temporal archive for substances incorporated into the feather during growth, including corticosterone, which is the primary avian glucocorticoid and a stress-associated hormone. Here, we analysed the WTE feather pools to investigate annual variations in feather corticosterone (fCORT), POPs (OCs and PBDEs), and stable carbon and nitrogen isotopes (SIs; dietary proxies). We examined whether the expected fluctuations in POPs affected fCORT (8-94 pg. mm-1) in the WTE pairs. Despite clear temporal declining trends in POP concentrations (p < 0.01), we found no significant associations between fCORT and POPs or SIs (p > 0.05 in all cases). Our results do not support fCORT as a relevant biomarker of contaminant-mediated effects in WTEs despite studying a highly contaminated population. However, although not detecting a relationship between fCORT, POP contamination and diet, fCORT represents a non-destructive and retrospective assessment of long-term stress physiology in wild raptors otherwise not readily available.

Mercury Exposure in Birds of Prey from Norway: Relation to Stable Carbon and Nitrogen Isotope Signatures in Body Feathers.

Mercury (Hg) and stable carbon and nitrogen isotope ratios were analysed in body feathers from nestlings of white-tailed eagles (Haliaeetus albicilla) (WTE; n = 13) and Northern goshawks (Accipiter gentilis) (NG; n = 8) and in red blood cells (RBC) from NG (n = 11) from Norway. According to linear mixed model, species factor was significant in explaining the Hg concentration in feathers (LMM; p < 0.001, estimate (WTE) = 2.51, 95% CI = 1.26, 3.76), with concentrations higher in WTE (3.01 ± 1.34 µg g-1 dry weight) than in NG (0.51 ± 0.34 µg g-1 dry weight). This difference and the isotopic patterns for each species, likely reflect their diet, as WTE predominantly feed on a marine and higher trophic-chain diet compared to the terrestrial NG. In addition, Hg concentrations in RBCs of NG nestlings were positively correlated with feather Hg concentrations (Rho = 0.77, p = 0.03), supporting the potential usefulness of nestling body feathers to biomonitor and estimate Hg exposure. Hg levels in both species were generally below the commonly applied toxicity threshold of 5 µg g-1 in feathers, although exceeded in two WTE (6.08 and 5.19 µg g-1 dry weight).

Trophic Dynamics of Mercury in the Baltic Archipelago Sea Food Web: The Impact of Ecological and Ecophysiological Traits.

We investigated trophic dynamics of Hg in the polluted Baltic Archipelago Sea using established trophic magnification (TMFs) and biomagnification factors (BMFs) on a comprehensive set of bird, fish, and invertebrate species. As different ecological and ecophysiological species traits may affect trophic dynamics, we explored the effect of food chain (benthic, pelagic, benthopelagic) and thermoregulatory strategy on trophic total Hg (THg) dynamics, using different approaches to accommodate benthopelagic species and normalize for trophic position (TP). We observed TMFs and most BMFs greater than 1, indicating overall THg biomagnification. We found significantly higher pelagic TMFs (3.58-4.02) compared to benthic ones (2.11-2.34) when the homeotherm bird species were excluded from models, but not when included. This difference between the benthic and pelagic TMFs remained regardless of how the TP of benthopelagic species was modeled, or whether TMFs were normalized for TP or not. TP-corrected BMFs showed a larger range (0.44-508) compared to BMFs representing predator-prey concentration ratios (0.05-82.2). Overall, the present study shows the importance of including and evaluating the effect of ecological and ecophysiological traits when investigating trophic contaminant dynamics.

Ecosystem specific accumulation of organohalogenated compounds: A comparison between adjacent freshwater and terrestrial avian predators.

Insight into processes determining the exposure of organohalogenated contaminants (OHCs) in wildlife might be gained from comparing predators in different ecosystems. This study compared two avian predator species with similar food chain lengths: the goldeneye duck (Bucephala clangula) and the tawny owl (Strix aluco) breeding in adjacent freshwater- and terrestrial ecosystems in central Norway. We measured lipophilic organochlorines (OCs) and protein-bound perfluorinated substances (PFASs) in eggs of the two species over 21 years (1999-2019). Across years, the proportional distribution of OCs (∼90% of the ΣOHC load) relative to PFASs (∼10%) was similar in the two species. Moreover, ΣOC concentrations were similar between the species, but PFAS compounds were 2-12 times higher in the goldeneyes than in tawny owls. OC-pesticides dominated in tawny owls (∼60% of ΣOC), whereas persistent polychlorinated biphenyl (PCBs) congeners were the main OC components in goldeneyes (∼70% of ΣOC). The lipid-normalized concentrations of most OC-pesticides and the less persistent PCB101 declined significantly in both species. Hexachlorobenzene (HCB), p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), and more persistent PCBs decreased in tawny owls, while they tended to increase in goldeneyes. The increase in HCB was particulary robust. Among the PFASs, contrasted temporal trends were found across the species for four out of 11 compounds: PFOS declined while most perfluorocarboxylic acids (PFCAs) increased in tawny owls. In contrast, most PFASs were stable in goldeneyes. Moreover, there was no annual covariance between the OHC exposure in the two species: i.e., high concentrations in one species in a given year did not translate into high concentrations in the other. Hence, the two avian predators in adjacent ecosystems seem to be subject to different processes determining the OHC exposure, probably related to variation in diet and climate, long-range transport of different contaminants, and emissions of pollution locally.

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

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

Legacy and emerging organohalogenated compounds in feathers of Eurasian eagle-owls (Bubo bubo) in Norway: Spatiotemporal variations and associations with dietary proxies (δ13C and δ15N).

The occurrence of organohalogenated compounds (OHCs) in wildlife has received considerable attention over the last decades. Among the matrices used for OHCs biomonitoring, feathers are particularly useful as they can be collected in a minimally or non-invasive manner. In this study, concentrations of various legacy OHCs -polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs)-, as well as emerging OHCs -per- and polyfluoroalkyl substances (PFAS) and organophosphate ester flame retardants (OPEs)- were determined in feathers of 72 Eurasian eagle-owls (Bubo bubo) from Norway, with the goal of studying spatiotemporal variation using a non-invasive approach. Molted feathers were collected at nest sites from northern, central and southern Norway across four summers (2013-2016). Additionally, two museum-archived feathers from 1979 to 1989 were included. Stable carbon (δ13C) and nitrogen isotopes (δ15N) were used as dietary proxies. In total, 11 PFAS (sum range 8.25-215.90 ng g-1), 15 PCBs (4.19-430.01 ng g-1), 6 OCPs (1.48-220.94 ng g-1), 5 PBDEs (0.21-5.32 ng g-1) and 3 OPEs (4.49-222.21 ng g-1) were quantified. While we observed large variation in the values of both stable isotopes, suggesting a diverse diet of the eagle-owls, only δ13C seemed to explain variation in PFAS concentrations. Geographic area and year were influential factors for δ15N and δ13C. Considerable spatial variation was observed in PFAS levels, with the southern area showing higher levels compared to northern and central Norway. For the rest of OHCs, we observed between-year variations; sum concentrations of PCBs, OCPs, PBDEs and OPEs reached a maximum in 2015 and 2016. Concentrations from 1979 to 1989 were within the ranges observed between 2013 and 2016. Overall, our data indicate high levels of legacy and emerging OHCs in a top predator in Norway, further highlighting the risk posed by OHCs to wildlife.

Spatiotemporal Analysis of Perfluoroalkyl Substances in White-Tailed Eagle (Haliaeetus albicilla) Nestlings from Northern Norway-A Ten-Year Study.

The white-tailed eagle (Haliaeetus albicilla) in Scandinavia has suffered from impaired reproduction due to high exposure to industrial pollution between the 1960s and 1980s. While population numbers are rising again, new contaminants, such as per- and polyfluoroalkyl substances (PFAS), are increasingly found in high trophic avifauna and are of concern to potentially impact once again on population health. In the present study, we examined PFAS levels in plasma of white-tailed eagle nestlings from northern Norway over the last decade (2008-2017). While PFOA and PFNA exposure did not follow a significant time trend, PFOS and PFHxS concentrations decreased over time, and ≥C11 perfluorinated carboxylic acids only seem to level off during the last four years. This may in fact be the first evidence for a change in the trend for some of these compounds. Furthermore, since several PFAS are expected to be highly present in aqueous film-forming foams used at airports, we also investigate the potential of the two main airports in the region to act as hotspots for PFAS. Our results indeed show decreasing exposure to PFOA with distance to the airports. Altogether, our results seem to show that legislation actions are effective, and continued concern for PFAS exposure of high trophic wildlife is still warranted, even in the northern environment.

Two Decades of Mercury Concentrations in Barents Sea Polar Bears (Ursus maritimus) in Relation to Dietary Carbon, Sulfur, and Nitrogen.

Temporal trends of total mercury (THg) were examined in female polar bear (Ursus maritimus) hair (n = 199) from the Barents Sea in 1995-2016. In addition, hair values of stable isotopes (n = 190-197) of carbon (δ13C), sulfur (δ34S), and nitrogen (δ15N) and information on breeding status, body condition, and age were obtained. Stable isotope values of carbon and sulfur reflect dietary source (e.g., marine vs terrestrial) and the nitrogen trophic level. Values for δ13C and δ34S declined by -1.62 and -1.18‰ over the time of the study period, respectively, while values for δ15N showed no trend. Total Hg concentrations were positively related to both δ13C and δ34S. Yearly median THg concentrations ranged from 1.61 to 2.75 µg/g and increased nonlinearly by 0.86 µg/g in total over the study. Correcting THg concentrations for stable isotope values of carbon and sulfur and additionally breeding status and age slightly accelerated the increase in THg concentrations; however, confidence intervals of the raw THg trend and the corrected THg trend had substantial overlap. The rise in THg concentrations in the polar bear food web was possibly related to climate-related re-emissions of previously stored Hg from thawing sea-ice, glaciers, and permafrost.

Accumulation of Short-, Medium-, and Long-Chain Chlorinated Paraffins in Marine and Terrestrial Animals from Scandinavia.

Short-, medium-, and long-chain chlorinated paraffins (SCCPs, MCCPs, and LCCPs) have a wide range of physical-chemical properties, indicating their varying bioaccumulation tendencies in marine and terrestrial ecosystems. However, there are few empirical data to reveal such bioaccumulation tendencies. In this study, we analyzed SCCPs, MCCPs, and LCCPs in samples from 18 species at both low and high trophic levels of marine and terrestrial ecosystems from the Scandinavian region collected during the past decade. These included fish, seabirds, marine mammals, and terrestrial birds and mammals. SCCPs, MCCPs, and LCCPs were present in all the species, with concentrations ranging from 26-1500, 30-1600, 6.0-1200 ng/g lipid, respectively. Although MCCPs and SCCPs predominated in most species, many terrestrial species had generally higher concentrations of LCCPs than marine species. Terrestrial raptors in particular accumulated higher concentrations of LCCPs, including C24/25-which are predominant among very-long-chain components. LCCP concentrations were highest and predominated (55% of total CPs) in peregrine falcons in this study, which is the first report where concentrations of LCCPs surpass those of SCCPs and MCCPs in wildlife. The results also indicate biomagnification of SCCPs, MCCPs, and LCCPs in both marine and terrestrial food chains, but in-depth studies of specific food webs are needed.

White-Tailed Eagle (Haliaeetus albicilla) Body Feathers Document Spatiotemporal Trends of Perfluoroalkyl Substances in the Northern Environment.

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.

Human exposure to PFOS and mercury through meat from baltic harbour seals (Phoca vitulina).

The overall aim of the present study was to assess human exposure to environmental contaminants from consumption of harbour seal (Phoca vitulina) meat in the southwestern Baltic Sea. For this purpose, muscle tissue from harbour seals (n = 27) was sampled from Danish locations in the period 2005-2015 and analysed for concentrations of total mercury (Hg), organochlorine contaminants such as polychlorinated biphenyls (PCBs) and organochlorine pesticides as well as perfluoroalkyl substances (PFAS) with particular focus on perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). Hg, ∑PCB, PFOS and PFOA concentrations in the muscle tissue ranged between 0.27 and 4.76 µg g-1 wet weight (ww; mean: 1.38 µg g-1 ww, n = 27), 12.2-137 ng g-1 ww (mean: 47.5 ng g-1 ww, n = 10), 6.95-33.6 ng g-1 ww (mean: 15.8 ng g-1 ww, n = 10) and 0.16-0.55 ng g-1 ww (mean: 0.28 ng g-1 ww, n = 10), respectively. We compared the concentrations with literature-derived human tolerable weekly intake (TWI) values for mercury (1.3 µg kg-1 week-1), ∑PCB (2.1 µg kg-1 week-1), PFOS (0.013 µg kg-1 week-1) and PFOA (0.006 µg kg-1 week-1). The comparisons showed that the weekly consumption of harbour seal meat by children (weighing 30 kg), women (weighing 60 kg) and men (weighing 80 kg) should not exceed 28, 57 and 76 g (for Hg), 1.3, 2.7 and 3.5 kg (for ∑PCB), 25, 50 and 67 g (for PFOS) and 640, 1290 and 1720 g (for PFOA). In conclusion, Hg and PFOS are the contaminants of most importance in seal meat from this area with respect to existing tolerable intake rates and risks of adverse human health effects.

Effects of Polar Bear and Killer Whale Derived Contaminant Cocktails on Marine Mammal Immunity.

Most controlled toxicity studies use single chemical exposures that do not represent the real world situation of complex mixtures of known and unknown natural and anthropogenic substances. In the present study, complex contaminant cocktails derived from the blubber of polar bears (PB; Ursus maritimus) and killer whales (KW; Orcinus orca) were used for in vitro concentration-response experiments with PB, cetacean and seal spp. immune cells to evaluate the effect of realistic contaminant mixtures on various immune functions. Cytotoxic effects of the PB cocktail occurred at lower concentrations than the KW cocktail (1 vs 16 µg/mL), likely due to differences in contaminant profiles in the mixtures derived from the adipose of each species. Similarly, significant reduction of lymphocyte proliferation occurred at much lower exposures in the PB cocktail (EC50: 0.94 vs 6.06 µg/mL; P < 0.01), whereas the KW cocktail caused a much faster decline in proliferation (slope: 2.9 vs 1.7; P = 0.04). Only the KW cocktail modulated natural killer (NK) cell activity and neutrophil and monocyte phagocytosis in a concentration- and species-dependent manner. No clear sensitivity differences emerged when comparing cetaceans, seals and PB. Our results showing lower effect levels for complex mixtures relative to single compounds suggest that previous risk assessments underestimate the effects of real world contaminant exposure on immunity. Our results using blubber-derived contaminant cocktails add realism to in vitro exposure experiments and confirm the immunotoxic risk marine mammals face from exposure to complex mixtures of environmental contaminants.

Japanese quail (Coturnix japonica) liver and thyroid gland histopathology as a result of in ovo exposure to the flame retardants tris(1,3-dichloro-2-propyl) phosphate and Dechlorane Plus.

Japanese quails (Coturnix japonica) were exposed in ovo to tris(1,3-dichloro-2-propyl) phosphate (TDCIPP; 500 ng/µl), Dechlorane Plus (DP; 500 ng/µl), or a 1:1 mixture of these two to investigate the effects on liver and thyroid gland morphology. Histological examination of 14-day-old quails showed that exposure to TDCIPP or the mixture induced hepatic sinusoidal dilatation. No marked effects were seen for DP alone. In addition, the mixture produced divergence of thyroid gland follicles and proliferation of follicular cells. Our study is the first demonstrating histopathological alterations as a result of exposure during early development to the flame retardants TDCIPP or a TDCIPP-DP mixture suggesting the need for further research efforts to investigate potential adverse health effects associated with exposure to these environmental chemicals in wild birds.

Trace element concentrations in feathers and blood of Northern goshawk (Accipiter gentilis) nestlings from Norway and Spain.

Information on trace element pollution in the terrestrial environment and its biota is limited compared to the marine environment. In the present study, we collected body feathers and blood of 37 Northern goshawk (Accipiter gentilis) nestlings from Tromsø (northern Norway), Trondheim (central Norway), and Murcia (southeastern Spain) to study regional exposure, hypothesizing the potential health risks of metals and other trace elements. Blood and body feathers were analyzed by a high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS) for aluminum (Al), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg) and lead (Pb). The influence of regional differences, urbanization and agricultural land usage in proximity to the nesting Northern goshawks was investigated using particular spatial analysis techniques. Most trace elements were detected below literature blood toxicity thresholds, except for elevated concentrations (mean ± SD µgml-1 ww) found for Zn (5.4 ± 1.5), Cd (0.00023 ± 0.0002), and Hg (0.021 ± 0.01). Corresponding mean concentrations in feathers (mean ± SD µgg-1 dw) were 82.0 ± 12.4, 0.0018 ± 0.002, and 0.26 ± 0.2 for Zn, Cd and Hg respectively. Multiple linear regressions indicated region was a significant factor influencing Al, Zn, Se and Hg feather concentrations. Blood Cd and Hg concentrations were significantly influenced by agricultural land cover. Urbanization did not have a significant impact on trace element concentrations in either blood or feathers. Overall metal and trace element levels do not indicate a high risk for toxic effects in the nestlings. Levels of Cd in Tromsø and Hg in Trondheim were however above sub-lethal toxic threshold levels. For holistic risk assessment purposes it is important that the concentrations found in the nestlings of this study indicate that terrestrial raptors are exposed to various trace elements.

Immunomodulatory effects of exposure to polychlorinated biphenyls and perfluoroalkyl acids in East Greenland ringed seals (Pusa hispida).

To better elucidate the potential immune-related health effects of exposure to environmentally persistent organic pollutants (POP), such as polychlorinated biphenyls (PCBs) and perfluoroalkyl substances (PFASs), in ringed seals (Pusa hispida), a sentinel Arctic species, we assessed 1) associations between mitogen-induced lymphocyte proliferation and in vivo tissue contaminant burdens, and 2) the concentration-response effects of in vitro exposure to PFASs and PCB congeners on mitogen-induced lymphocyte proliferation. Upon in vitro contaminant exposure, the non-coplanar PCB congeners CB 138, 153, and 180, but not the coplanar CB 169, significantly reduced lymphocyte proliferation between 10 and 20µgg-1 ww. The respective in vitro EC50 values for these congeners were 13.3, 20.7, 20.8, and 54.6µgg-1 ww. No modulation of lymphocyte proliferation was observed upon in vitro exposure to two individual PFASs, perfluorooctane sulphonic acid (PFOS) and perfluorooctanoic acid (PFOA), at concentrations up to 1000ngg-1. In addition, no significant correlations were found between lymphocyte proliferation and any blood or blubber contaminant measured. Taken together, these data suggest this population of ringed seals is not currently at high risk of altered lymphocyte proliferation from exposure to the POPs or PFASs in this study.

Organophosphorus flame retardants in the European eel in Flanders, Belgium: Occurrence, fate and human health risk.

The present study investigated the levels, profiles and human health risk of organophosphorus flame retardants and plasticizers (PFRs) in wild European eels (Anguilla anguilla) from freshwater bodies in the highly populated and industrial Flanders region (Belgium). Yellow eels (n=170) were collected at 26 locations between 2000 and 2009 and for each site, muscle samples of 3-10 eels were pooled and analyzed (n=26). Muscle lipid percentages varied widely between 2.4% and 21%, with a median value of 10%. PFRs were detected in all pooled samples in the order of tris-2-chloroisopropyl phosphate (TCIPP)>triphenyl phosphate (TPHP)>2-ethylhexyl diphenyl phosphate (EHDPHP)>tris-2-butoxyethyl phosphate (TBOEP)>tris-2-chloroethyl phosphate (TCEP)>tris-1,3-dichloro-2-propyl phosphate (TDCIPP). The median sum PFR concentration for all 26 sites was 44 ng/g lw (8.4 ng/g ww), and levels ranged between 7.0 and 330 ng/g lw (3.5 and 45 ng/g ww). Levels and profiles of PFRs in eels showed that sampling locations and river basin catchments are possible drivers of spatial variation in the aquatic environment. Median PFR concentrations were lower than those of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs). No correlation was observed between the PFR concentrations and lipid contents, suggesting that the accumulation of PFRs is not primarily associated with lipids. Human exposure to PFRs, due to consumption of wild eels, seems to be of minor importance compared to other potential sources, such as inhalation and ingestion of indoor dust. Nevertheless, considering the very limited data available on PFRs in human dietary items and their expected increasing use after the phase out of PBDEs and HBCDs, further investigations on PFRs in biota and human food items are warranted.

Exploring avian exposure to parent polycyclic aromatic hydrocarbons (PAHs): Using the common eider Somateria mollissima in a global context.

Compared to other organic contaminants, birds are rarely studied for their exposure to polycyclic aromatic hydrocarbons (PAHs), mainly due to their effective metabolization of parent PAHs. However, as some studies suggest, exposure to PAHs may result in adverse health effects including decreased survival, especially following oil spills. In the present study, we analyzed samples from a sea duck, the common eider Somateria mollissima including feathers, preen oil, blood, liver and bile, to evaluate whether non- lethally collected samples could be reliably used for avian biomonitoring strategies. Phenanthrene was the only individual PAH detected across sample types, with the highest concentration found in preen gland and the lowest in blood. Significant differences in concentrations were observed between bile vs preen gland and liver vs preen gland, while for most compounds neither blood nor feathers showed detectable levels of parent PAHs. Therefore, the utility of those sample types for PAH exposure assessment may be limited and should be interpreted with caution, moreover as several physiological factors may affect them. Additionally, we also provide a comparison with the available literature to review current avian PAH exposure assessment and outline future research focused needs.

Advancing exposure assessment approaches to improve wildlife risk assessment.

The exposure assessment component of a Wildlife Ecological Risk Assessment aims to estimate the magnitude, frequency, and duration of exposure to a chemical or environmental contaminant, along with characteristics of the exposed population. This can be challenging in wildlife as there is often high uncertainty and error caused by broad-based, interspecific extrapolation and assumptions often because of a lack of data. Both the US Environmental Protection Agency (USEPA) and European Food Safety Authority (EFSA) have broadly directed exposure assessments to include estimates of the quantity (dose or concentration), frequency, and duration of exposure to a contaminant of interest while considering "all relevant factors." This ambiguity in the inclusion or exclusion of specific factors (e.g., individual and species-specific biology, diet, or proportion time in treated or contaminated area) can significantly influence the overall risk characterization. In this review, we identify four discrete categories of complexity that should be considered in an exposure assessment-chemical, environmental, organismal, and ecological. These may require more data, but a degree of inclusion at all stages of the risk assessment is critical to moving beyond screening-level methods that have a high degree of uncertainty and suffer from conservatism and a lack of realism. We demonstrate that there are many existing and emerging scientific tools and cross-cutting solutions for tackling exposure complexity. To foster greater application of these methods in wildlife exposure assessments, we present a new framework for risk assessors to construct an "exposure matrix." Using three case studies, we illustrate how the matrix can better inform, integrate, and more transparently communicate the important elements of complexity and realism in exposure assessments for wildlife. Modernizing wildlife exposure assessments is long overdue and will require improved collaboration, data sharing, application of standardized exposure scenarios, better communication of assumptions and uncertainty, and postregulatory tracking. Integr Environ Assess Manag 2024;20:674-698. © 2023 SETAC.

Long-term monitoring of exposure to toxic and essential metals and metalloids in the tawny owl (Strix aluco): Temporal trends and influence of spatial patterns.

As a result of regulatory decisions, atmospheric deposition of most toxic metals and metalloids (MEs) has decreased in Europe over the past few decades. However, little is known about how this reduction translates into exposure at higher trophic levels in the terrestrial environment where temporal trends may be spatially heterogeneous due to local current or legacy sources of emissions (e.g., industry) or long-range transport of elements (e.g., marine transport). The aim of this study was to characterize temporal and spatial trends of exposure to MEs in terrestrial food webs using a predatory bird, the tawny owl Strix aluco, as a biomonitor. Toxic (Al, As, Cd, Hg, Pb) and essential/beneficial (B, Co, Cu, Mn, Se) elemental concentrations were measured in feathers of nest-captured females from 1986 to 2016, extending a previous study published over the time-series 1986-2005 (n = 1051), in a breeding population in Norway. A drastic decline over time was shown for the toxic MEs (-97 % for Pb, -89 % for Cd, -48 % for Al, and -43 % for As) except Hg. The beneficial elements B, Mn, and Se showed oscillations but an overall decline (-86 %, -34 %, and -12 %, respectively) whereas the essentials Co and Cu did not exhibit significant trends. The distance to potential sources of contamination influenced both the spatial patterns of concentrations in owl feathers and their temporal trends. The accumulation of As, Cd, Co, Mn and Pb was overall higher in the vicinity of sites recorded as polluted, and a greater temporal decrease of As, B, and Cd concentrations was found in the areas of further distance to polluted sites. The decrease of Pb concentrations was sharper further from the coast during the 1980s than in coastal areas, while the opposite was observed for Mn. The levels of Hg and Se were higher in coastal areas, and Hg temporal trends differed according to the distance to the coast. This study highlights the valuable insights provided by long-term survey of wildlife exposure to pollutants and landscape indicators to reveal regional or local patterns and detect unexpected events, data that are crucial for regulation and conservation of ecosystem health.