Spatiotemporal patterns and relationships among the diet, biochemistry, and exposure to flame retardants in an apex avian predator, the peregrine falcon

Exposure of Peregrine Falcons to Halogenated Flame Retardants: A 30 Year Retrospective Biomonitoring Study across North America

Compared to aquatic ecosystem, terrestrial systems have been subjected to fewer investigations on the exposure to halogenated flame retardants (HFRs). Our study utilized peregrine falcon eggs collected from multiple habitats across North America to retrospectively explore both spatial distribution and temporal changes in legacy (e.g., polybrominated diphenyl ethers) and alternative HFRs over a 30 year period (1984-2016). The results reveal intensive HFR exposure in terrestrial ecosystems and chemical-specific spatiotemporal distribution patterns. The correlations between egg levels of the selected HFRs and human population density clearly illustrated a significant urban influence on the exposure of this wildlife species to these HFRs and subsequent maternal transfer to their eggs. Temporal analyses suggest that, unlike aquatic systems, terrestrial ecosystems may undergo continual exposure to consistently high levels of legacy HFRs for a long period of time. Our findings collectively highlight the effectiveness of using peregrine eggs to monitor terrestrial exposure to HFRs and other bioaccumulative chemicals and the need for continuous monitoring of HFRs in terrestrial ecosystems.

Interspecies Mobility of Organohalide Respiration Gene Clusters Enables Genetic Bioaugmentation

Anthropogenic organohalide pollutants pose a severe threat to public health and ecosystems. In situ bioremediation using organohalide respiring bacteria (OHRB) offers an environmentally friendly and cost-efficient strategy for decontaminating organohalide-polluted sites. The genomic structures of many OHRB suggest that dehalogenation traits can be horizontally transferred among microbial populations, but their occurrence among anaerobic OHRB has not yet been demonstrated experimentally. This study isolates and characterizes a novel tetrachloroethene (PCE)-dechlorinating Sulfurospirillum sp. strain SP, distinguishing itself among anaerobic OHRB by showcasing a mechanism essential for horizontal dissemination of reductive dehalogenation capabilities within microbial populations. Its genetic characterization identifies a unique plasmid (pSULSP), harboring reductive dehalogenase and de novo corrinoid biosynthesis operons, functions critical to organohalide respiration, flanked by mobile elements. The active mobility of these elements was demonstrated through genetic analyses of spontaneously emerging nondehalogenating variants of strain SP. More importantly, bioaugmentation of nondehalogenating microcosms with pSULSP DNA triggered anaerobic PCE dechlorination in taxonomically diverse bacterial populations. Our results directly support the hypothesis that exposure to anthropogenic organohalide pollutants can drive the emergence of dehalogenating microbial populations via horizontal gene transfer and demonstrate a mechanism by which genetic bioaugmentation for remediation of organohalide pollutants could be achieved in anaerobic environments.

The influence of environmental and ecological factors on the accumulation and distribution of short- and long-chain perfluoroalkyl acids in a mid-trophic avian insectivore

Perfluoroalkyl acids (PFAAs) include perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), and perfluorodecane sulfonic acid (PFDS), as well as increasingly used alternative short-chain perfluorosulfonic acids (PFSAs) and short- and long-chain (≥C₉) perfluorocarboxylic acids (PFCAs). In the present study, tissues of tree swallows (Tachycineta bicolor) from two sites in southern Ontario, Canada, were analyzed for 17 individual PFAAs and showed egg and nestling tissue (liver, carcass) profiles dominated by PFOS (57-66%). The remaining PFAAs contributed ≤7% each, although collectively the long-chain PFCAs comprised 21-29% of the PFAAs. The short-chain PFSAs and PFCAs were among the lowest concentrations, suggesting that despite increased production and use of these alternative PFAAs, they are not accumulated to the same extent as the long-chain PFSAs and PFCAs. PFOS, PFDS, and some long-chain PFCAs were significantly higher in eggs than in livers and carcasses, whereas PFOA and the two short-chain PFCAs were significantly higher in nestling tissues than in eggs. For the two short-chain PFSAs, concentrations were similar among tissues. Tree swallow tissues at the site near a wastewater treatment plant (WWTP) outfall showed higher concentrations of PFOS, PFDS, PFHxS, and some long-chain PFCAs than tree swallows sampled at the nearby reference site; however, the influence of the WWTP was more equivocal for PFOA, other long-chain PFCAs, and short-chain PFSAs and PFCAs. Carbon stable isotopes (δ¹³C) and fatty acid signatures indicated that the diets of the WWTP swallows were more terrestrial than the reference swallows. Nonetheless, models considering environmental and ecological variables indicated that site was often the primary driver of PFAA variation among the swallows, with less or no influence of dietary patterns, or sex or body condition, revealing that of WWTP effluent can be an important environmental source of the major PFAAs in tree swallows.

Past and future: Urbanization and the avian endocrine system

Urban environments are evolutionarily novel and differ from natural environments in many respects including food and/or water availability, predation, noise, light, air quality, pathogens, biodiversity, and temperature. The success of organisms in urban environments requires physiological plasticity and adjustments that have been described extensively, including in birds residing in geographically and climatically diverse regions. These studies have revealed a few relatively consistent differences between urban and non-urban conspecifics. For example, seasonally breeding urban birds often develop their reproductive system earlier than non-urban birds, perhaps in response to more abundant trophic resources. In most instances, however, analyses of existing data indicate no general pattern distinguishing urban and non-urban birds. It is, for instance, often hypothesized that urban environments are stressful, yet the activity of the hypothalamus-pituitary-adrenal axis does not differ consistently between urban and non-urban birds. A similar conclusion is reached by comparing blood indices of metabolism. The origin of these disparities remains poorly understood, partly because many studies are correlative rather than aiming at establishing causality, which effectively limits our ability to formulate specific hypotheses regarding the impacts of urbanization on wildlife. We suggest that future research will benefit from prioritizing mechanistic approaches to identify environmental factors that shape the phenotypic responses of organisms to urbanization and the neuroendocrine and metabolic bases of these responses. Further, it will be critical to elucidate whether factors affect these responses (a) cumulatively or synergistically; and (b) differentially as a function of age, sex, reproductive status, season, and mobility within the urban environment. Research to date has used various taxa that differ greatly not only phylogenetically, but also with regard to ecological requirements, social systems, propensity to consume anthropogenic food, and behavioral responses to human presence. Researchers may instead benefit from standardizing approaches to examine a small number of representative models with wide geographic distribution and that occupy diverse urban ecosystems.

Hepatic Gene Expression Profiling of American Kestrels (Falco sparverius) Exposed In Ovo to Three Alternative Brominated Flame Retardants

Simple Summary

Brominated flame retardants are added to many consumer products to reduce flammability. While some of these compounds have been or are being phased out due to toxicity concerns, many other substitute or alternative flame retardant chemicals are still in use and being detected in the environment. There is growing evidence that these alternatives exhibit properties and environmental fates similar to those they replaced. However, little information is available on their potential toxic effects in wildlife. Here, the effects of several flame retardants on American kestrel hatchlings at concentrations observed in wild birds, were investigated by examining gene expression changes in the liver. Effects on the immune, thyroid, and other biological pathways were observed, suggesting that birds exposed as developing embryos in the egg can still exhibit effects upon hatching.

Abstract

A number of brominated flame retardants (BFRs) have been reported to interfere with the thyroid signaling pathway and cause oxidative stress in birds, yet the underlying shifts in gene expression associated with these effects remain poorly understood. In this study, we measured hepatic transcriptional responses of 31 genes in American kestrel (Falco sparverius) hatchlings following in ovo exposure to one of three high-volume alternative BFRs: 1,2-bis(2,4,6-tribromophenoxy) ethane (BTPBE), bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (TBPH), or 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB). Hatchling kestrels exhibited shifts in the expression of genes related to oxidative stress (CYP, GSTA, SOD, and GPX1), thyroid hormone metabolism and transport (DIO1, DIO2, and TTR), lipid and protein metabolism (PPAR, HMGCR, FAB1, and LPL), and cytokine-mediated inflammation (TLR3, IL18, IRF7, STAT3, RACK1, and CEBPB). Male and female hatchlings differed in which genes were differentially expressed, as well as the direction of the effect (up- vs. downregulation). These results build upon our previous findings of increased oxidative stress and disrupted thyroid signaling pathway in the same hatchlings. Furthermore, our results indicate that inflammatory responses appear to occur in female hatchlings exposed to BTBPE and EHTBB in ovo. Gene expression analysis revealed multiple affected pathways, adding to the growing evidence that sublethal physiological effects are complex and are a concern for birds exposed to BTBPE, EHTBB, or TBPH in ovo.

Flame retardants and their associations with thyroid hormone-related variables in northern fulmars from the Faroe Islands

Flame retardants (FRs) are widely reported in tissues of seabirds including birds sampled from remote areas. There is evidence that FRs can disrupt the hypothalamic-pituitary-thyroid (HPT) axis in seabirds, although information is limited on thyroid-related mechanisms and effects. This study investigated the associations between concentrations of polybrominated diphenyl ethers (PBDEs) and other FRs, and changes in the HPT axis in northern fulmars (Fulmarus glacialis) from the Faroe Islands (North Atlantic). Plasma concentrations of thyroid hormones (THs), hepatic deiodinase type 1 (D1) activity, and transcription of selected TH-related genes in liver were used as markers of HPT axis changes. Liver concentrations of a certain PBDE congeners and other FRs including pentabromoethylbenzene (PBEB), dechlorane 602 (Dec-602), and dechlorane plus (DP) were associated with changes in thyroid status. Specifically, liver PBDE, PBEB and Dec-602 concentrations were associated with plasma TH levels (free thyroxine [FT₄] and total triiodothyronine [TT₃]). Liver DP concentrations were positively correlated with the TT₄:FT₄ ratios and mRNA levels of UDP-glucuronyltransferase-1, while those of PBEB were negatively associated with TT₄:TT₃ ratios and D1 activity. D1 activity was also positively associated with the tri-, tetra- and hexa-BDE congeners. Moreover, transcription of ABCC2, a hepatic TH transporter, was associated with certain liver PBDE concentrations. Although PBDEs and other FRs may be potential inhibitors of D1 activity, only a few of the targeted FRs had modest associations with hepatic D1 activity. Regardless, the relationships reported herein indicated that exposure to moderate levels of FRs can be associated with thyroid axis perturbation at the molecular/biochemical levels in this North Atlantic seabird species.

Thyroid disruption and oxidative stress in American kestrels following embryonic exposure to the alternative flame retardants, EHTBB and TBPH

Brominated flame retardant chemicals, such as 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB) (CAS #: 183658-27-7) and bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (TBPH) (CAS #: 26040-51-7), have been detected in avian tissues and eggs from remote regions. Exposure to EHTBB and TBPH has been shown to cause oxidative stress and altered thyroid function in rodents and fish, yet no controlled studies have examined potential adverse effects of exposure in birds. Because flame retardants have been detected in wild raptors, we used American kestrels (Falco sparverius) as a model raptor to determine whether in ovo exposure to EHTBB or TBPH affected growth, hatching success, oxidative stress, or thyroid function. We exposed kestrel embryos to nominal concentrations (10, 50, or 100 ng g^-1 egg weight) of EHTBB and TBPH via egg-injection on embryonic day 5. Embryonic exposure (~23 d) to EHTBB increased thyroid gland mass, reduced glandular colloid and total thyroxine (T4) in hatchling males and females, whereas deiodinase enzyme activity increased in males but decreased in females. Hatchlings exposed to TBPH in ovo exhibited reduced colloid and increased oxidative stress. Although exposure to EHTBB and TBPH caused several physiological effects (e.g., heart and brain mass), only exposure to 50 ng g^-1 EHTBB appeared to reduce hatching success. Our results suggest these flame retardants may be hazardous for predatory birds. Future research should evaluate long-term survival and fitness consequences in birds exposed to these chemicals.

Interdependence of Thyroid and Corticosteroid Signaling in Vertebrate Developmental Transitions

Post-embryonic acute developmental processes mainly allow the transition from one life stage in a specific ecological niche to the next life stage in a different ecological niche. Metamorphosis, an emblematic type of these post-embryonic developmental processes, has occurred repeatedly and independently in various phylogenetic groups throughout metazoan evolution, such as in cnidarian, insects, molluscs, tunicates, or vertebrates. This review will focus on metamorphoses and developmental transitions in vertebrates, including typical larval metamorphosis in anuran amphibians, larval and secondary metamorphoses in teleost fishes, egg hatching in sauropsids and birth in mammals. Two neuroendocrine axes, the hypothalamic-pituitary-thyroid and the hypothalamic-pituitary-adrenal/interrenal axes, are central players in the regulation of these life transitions. The review will address the molecular and functional evolution of these axes and their interactions. Mechanisms of integration of internal and environmental cues, and activation of these neuroendocrine axes represent key questions in an “eco-evo-devo” perspective of metamorphosis. The roles played by developmental transitions in the innovation, adaptation, and plasticity of life cycles throughout vertebrates will be discussed. In the current context of global climate change and habitat destruction, the review will also address the impact of environmental factors, such as global warming and endocrine disruptors on hypothalamic-pituitary-thyroid and hypothalamic-pituitary-adrenal/interrenal axes, and regulation of developmental transitions.

Patterns and Trends of Polybrominated Diphenyl Ethers in Bald Eagle Nestlings in Minnesota and Wisconsin, USA

We measured concentrations of up to 17 polybrominated diphenyl ethers (PBDEs) in plasma of 492 bald eagle (Haliaeetus leucocephalus) nestlings between 1995 and 2017 from 12 study areas in Wisconsin and Minnesota, USA. Geometric mean concentrations of the sum of 9 PBDE congeners (∑PBDE) measured across all years ranged from 2.88 to 10.8 µg/L, and nestlings in urban areas had higher concentrations than those in remote locations. Region-wide from 2006 through 2017, we found that ∑PBDEs declined by 3.8% annually and congeners BDE-47, -99, and -100 declined by 5.6 to 6.5%, whereas BDE-153 and -154 had no significant declines. When categorized by waterbody type, nestlings from Great Lakes and river study areas had higher concentrations of ∑PBDEs than those at inland lakes, but river study areas spanned the extremes. From 2006 to 2017, ∑PBDEs declined by 7.3% annually in Great Lakes nestlings and by 3.2% in nestlings along rivers, and increased by 32.7% at inland lakes. Using a longer dataset (1995-2015), we found that ∑PBDEs declined in Lake Superior nestlings by 3.3% annually. Our results show that PBDEs declined in bald eagle nestling plasma in most study areas since PBDE production was reduced, but that concentrations remain high near urban centers and that trends differ by congener, study area, and waterbody type. Environ Toxicol Chem 2021;40:1606-1618. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Influence of perfluoroalkyl acids and other parameters on circulating thyroid hormones and immune-related microRNA expression in free-ranging nestling peregrine falcons

Exposure to certain perfluoroalkyl acids (PFAAs) can have considerable effects on the endocrine and immune systems, although such effects remain largely uncharacterized in wildlife. Using an apex avian predator, we investigated possible relationships of thyroid hormones (THs), specifically free (F) and total (T) thyroxine (FT4; TT4) and triiodothyronine (FT3; TT3), and the expression of an immune-related microRNA biomarker (i.e., miR-155), with the concentrations of 11 PFAAs in nestling peregrine falcons (Falco peregrinus). Nestling peregrines (n = 56; usually two chicks of each sex per nest) were blood sampled when 23 ± 4 days old in urban and rural regions of the Laurentian Great Lakes Basin (Ontario, Canada) in 2016 and 2018. The circulating concentrations of several PFAAs were significantly associated with THs and estimated thyroid gland activity (TT3:TT4; FT3:FT4), including PFHxS (FT3; FT3:FT4), PFDS (TT3; TT3:TT4), PFOA (TT4; FT3:FT4), PFTeDA (TT4; FT3:FT4), PFHxDA (TT4; TT3:TT4) and ΣPFCAs (TT4). Our novel evaluation of miR-155 in peregrine nestlings identified significantly negative relationships of plasma miR-155 counts with PFHxS and PFOA concentrations, indicating potential down-regulation of miR-155 expression and impaired immunity. Several PFAA homologues significantly predicted the variation in THs and miR-155 in conjunction with year (e.g., inter-annual differences in weather, ambient temperature, rainfall), region (urban/rural), nestling age, and/or diet (trophic position; δ¹⁵N), which suggests that multiple environmental and biological stressors, including PFAA exposure, influenced thyroid activity and immune function in these nestlings. Further research is warranted to identify the mechanisms and additional impacts of PFAA-related thyroid and immune disruption on the growth, development, and health risks in developing birds.

A review of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane in the environment and assessment of its persistence, bioaccumulation and toxicity

Following the ban of many historically-used flame retardants (FRs), numerous replacement chemicals have been produced and used in products, with some being identified as environmental contaminants. One of these replacement flame retardants is 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (DBE-DBCH; formerly abbreviated as TBECH), which to date has not been identified for risk assessment and potential regulation. DBE-DBCH technical mixtures consist largely of α- and β-diastereomers with trace amounts of γ- and δ-DBE-DBCH. The α- and β-isomers are known contaminants in various environmental media. While current global use and production volumes of DBE-DBCH are unknown, recent studies identified that DBE-DBCH concentrations were among the highest of the measured bromine-based FRs in indoor and urban air in Europe. Yet our mass balance fugacity model and modeling of the physical-chemical properties of DBE-DBCH estimated only 1% partitioning to air with a half-life of 2.2 d atmospherically. In contrast, our modeling characterized DBE-DBCH adsorbing strongly to suspended particulates in the water column (~12%), settling onto sediment (2.5%) with minimal volatilization, but with most partitioning and adsorbing strongly to soil (~85%) with negligible volatilization and slow biodegradation. Our modeling further predicted that organisms would be exposed to DBE-DBCH through partitioning from the dissolved aquatic phase, soil, and by diet, and given its estimated logKow (5.24) and a half-life of 1.7 d in fish, DBE-DBCH is expected to bioaccumulate into lipophilic tissues. Low concentrations of DBE-DBCH are commonly measured in biota and humans, possibly because evidence suggests rapid metabolism. Yet toxicological effects are evident at low exposure concentrations: DBE-DBCH is a proven endocrine disruptor of sex and thyroid hormone pathways, with in vivo toxic effects on reproductive, metabolic, and other endpoints. The objectives of this review are to identify the current state of knowledge concerning DBE-DBCH through an evaluation of its persistence, potential for bioaccumulation, and characterization of its toxicity, while identifying areas for future research.

4,5,6,7-Tetrabromo-2,3-dihydro-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenyl)-1H-indene (OBTMPI): Levels in humans and in silico toxicological profiles

Limited human exposure and toxicity data are currently available for 4,5,6,7-Tetrabromo-2,3-dihydro-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenyl)-1H-indene (OBTMPI), a flame retardant often used for high temperature application of various polymer materials. Levels of OBTMPI in a cohort population that includes children and their co-residing parents (n = 217) in Canada were determined. Detection frequency of OBTMPI in the samples was 22.6%. OBTMPI levels were in general at sub-to low ng/g lipid weight level with a 95th percentile at 15.6 ng/g lipid weight. Compared to an earlier study conducted in 2008-2009 in the same region, results from this study show an increase in both detection frequency and concentration of OBTMPI. In silico toxicity predictions using Multicase CaseUltra and Leadscope Model Applier suggested that OBTMPI, and its possible metabolites in humans, while unlikely to be carcinogenic or mutagenic, exhibit some estrogen antagonist, androgen antagonist and estrogen binding capability reflective of possible endocrine disrupting properties.

Perfluoroalkyl acids and sulfonamides and dietary, biological and ecological associations in peregrine falcons from the Laurentian Great Lakes Basin, Canada

Perfluoroalkyl substances (PFAS) are a large, diverse group of chemicals and several perfluoroalkyl acids (PFAAs) are known environmental contaminants. Wildlife exposure to PFAAs and precursors has been shown, but less is known regarding replacements such as shorter-chain PFAS. In the present study, exposure to a suite of PFAAs and associations with dietary, biological and ecological factors were investigated in populations of a sentinel apex species - the peregrine falcon (Falco peregrinus). Nestling blood (n = 57) and sibling eggs (n = 9) were sampled in 2016 and 2018 from nests in rural and urban regions across the Laurentian Great Lakes Basin, Canada. PFSAs (perfluorinated sulfonic acids) including PFHxS, PFOS, and PFDS were detected in most egg and plasma samples, whereas 11 PFCAs (perfluorinated carboxylic acids; C₅-C₁₄, C₁₆) compared to eight PFCAs (C₈-C₁₄, C₁₆) were detected in most eggs and plasma, respectively. Shorter-chain C₈-C₁₀ PFCAs were more dominant in plasma and longer-chain C₁₂-C₁₄ PFCAs in eggs, but profiles were similar for PFOS, PFDS, PFUdA and PFHxDA. The exposure to PFAAs in peregrine falcons is likely mediated by dietary factors such as foraging location (δ¹³C and δ³⁴S) and trophic position (δ¹⁵N) given the associations observed in eggs and nestling plasma, respectively. Moreover, significant relationships were observed for circulating ΣPFCAs and region (rural/urban), and nestling body condition after adjusting for sampling year and dietary tracers, suggesting that compared to rural nestlings, urban nestlings may be more exposed to ΣPFCAs and prone to their potential physiological impacts. Our findings highlight the importance of integrating dietary, biological and ecological factors when studying PFAS exposure in birds.

Integrated exposure assessment of northern goshawk (Accipiter gentilis) nestlings to legacy and emerging organic pollutants using non-destructive samples

In the present study, concentrations of legacy and emerging contaminants were determined in three non-destructive matrices (plasma, preen oil and body feathers) of northern goshawk (Accipiter gentilis) nestlings. Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs), together with emerging pollutants, including per- and polyfluorinated alkyl substances (PFASs), novel brominated flame retardants (NBFRs), phosphorus flame retardants (PFRs) and Dechlorane Plus isomers (DPs) were targeted. Plasma, preen oil and feather samples were collected from 61 goshawk nestlings in Norway (Trøndelag and Troms) in 2015 and 2016, and pollutant concentrations were compared between the three matrices. In plasma, PFASs were detected in the highest concentrations, ranging between 1.37 and 36.0 ng/mL, which suggests that the nestlings were recently and continuously exposed to these emerging contaminants, likely through dietary input. In preen oil, OCPs (169-3560 ng/g) showed the highest concentrations among the investigated compounds, consistent with their high lipophilicity. PFRs (2.60-314 ng/g) were the dominant compounds in feathers and are thought to originate mainly from external deposition, as they were not detected in the other two matrices. NBFRs and DPs were generally not detected in the nestlings, suggesting low presence of these emerging contaminants in their environment and/or low absorption. Strong and significant correlations between matrices were found for all POPs (r_s = 0.46-0.95, p < 0.001), except for hexachlorobenzene (HCB, r_s = 0.20, p = 0.13). Correlations for PFASs were less conclusive: linear perfluorooctane sulfonate (PFOS), perfluoroundecanoate (PFUnA), perfluorododecanoate (PFDoA) and perfluorotetradecanoate (PFTeA) showed strong and significant correlations between plasma and feathers (r_s = 0.42-0.72, p < 0.02), however no correlation was found for perfluorohexane sulfonate (PFHxS), perfluorononanoate (PFNA) and perfluorotridecanoate (PFTriA) (r_s = 0.05-0.33, p = 0.09-0.85). A lack of consistency between the PFAS compounds (contrary to POPs), and between studies, prevents concluding on the suitability of the investigated matrices for PFAS biomonitoring.

The influence of natural variation and organohalogenated contaminants on physiological parameters in white-tailed eagle (Haliaeetus albicilla) nestlings from Norway

Environmental exposure to organohalogenated contaminants (OHCs), even at low concentrations, may cause detrimental effects on the development and health of wild birds. The present study investigated if environmental exposure to OHCs may influence the variation of multiple physiological parameters in Norwegian white-tailed eagle (Haliaeetus albicilla) nestlings. Plasma and feather samples were obtained from 70 nestlings at two archipelagos in Norway in 2015 and 2016. The selected physiological parameters were plasma concentrations of thyroid hormones (thyroxine, T4 and triiodothyronine, T3), plasma proteins (prealbumin, albumin, α₁-, α₂-, β- and γ-globulins) and selected blood clinical chemical parameters (BCCPs) associated with liver and kidney functioning. Feather concentrations of corticosterone (CORT_f) were also included to investigate the overall stress level of the nestlings. Concentrations of all studied physiological parameters were within the ranges of those found in other species of free-living birds of prey nestlings and indicated that the white-tailed eagle nestlings were in good health. Our statistical models indicated that perfluoroalkyl substances (PFASs) and legacy OHCs, such as polychlorinated biphenyls, organochlorinated pesticides and polybrominated diphenyl ethers, influenced only a minor fraction of the variation of plasma thyroid hormones, prealbumin and CORT_f (5-15%), and partly explained the selected BCCPs (<26%). Most of the variation in each studied physiological parameter was explained by variation between nests, which is most likely due to natural physiological variation of nestlings in these nests. This indicates the importance of accounting for between nest variation in future studies. In the present nestlings, OHC concentrations were relatively low and seem to have played a secondary role compared to natural variation concerning the variation of physiological parameters. However, our study also indicates a potential for OHC-induced effects on thyroid hormones, CORT_f, prealbumin and BCCPs, which could be of concern in birds exposed to higher OHC concentrations than the present white-tailed eagle nestlings.

Early life exposure to triphenyl phosphate: Effects on thyroid function, growth, and resting metabolic rate of Japanese quail (Coturnix japonica) chicks

Triphenyl phosphate (TPHP; CAS # 115-86-6), a commonly used plasticizer and flame retardant, has been reported in wild birds and identified as a potential high-risk chemical. We exposed Japanese quail (Coturnix japonica) by in ovo injection, and once hatched, orally each day for 5 days to safflower oil (controls) or TPHP dissolved in vehicle at low (5 ng TPHP/g), mid (50 ng TPHP/g), or high (100 ng TPHP/g) nominal TPHP doses. The low TPHP dose reflected concentrations in wild bird eggs, with mid and high doses 10x and 20x greater to reflect potential increases in environmental TPHP concentrations in the future. Despite no effects on mRNA expression in thyroid-related genes, TPHP exposure enhanced thyroid gland structure in high TPHP males, but in females, suppressed thyroid gland structure and activity (all TPHP females), and circulating free triiodothyronine (high TPHP females only). Consistent with thyroidal changes, and compared to controls, mid and high TPHP chicks experienced significantly reduced resting metabolic rate (≤13%) and growth (≤53%); mid TPHP males and high TPHP females were significantly smaller. The observed thyroidal effects and suppressed growth and metabolic rate of the quail chicks suggest that TPHP may adversely affect the health of wild birds.

In ovo exposure to brominated flame retardants Part II: Assessment of effects of TBBPA-BDBPE and BTBPE on hatching success, morphometric and physiological endpoints in American kestrels

Tetrabromobisphenol A bis(2,3-dibromopropyl ether) (TBBPA-BDBPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTPBE) are both brominated flame retardants (BFRs) that have been detected in birds; however, their potential biological effects are largely unknown. We assessed the effects of embryonic exposure to TBBPA-BDBPE and BTBPE in a model avian predator, the American kestrel (Falco sparverius). Fertile eggs from a captive population of kestrels were injected on embryonic day 5 (ED5) with a vehicle control or one of three doses within the range of concentrations that have been detected in biota (nominal concentrations of 0, 10, 50 or 100 ng/g egg; measured concentrations 0, 3.0, 13.7 or 33.5 ng TBBPA-BDBPE/g egg and 0, 5.3, 26.8 or 58.1 ng BTBPE/g egg). Eggs were artificially incubated until hatching (ED28), at which point blood and tissues were collected to measure morphological and physiological endpoints, including organ somatic indices, circulating and glandular thyroid hormone concentrations, thyroid gland histology, hepatic deiodinase activity, and markers of oxidative stress. Neither compound had any effects on embryo survival through 90% of the incubation period or on hatching success, body mass, organ size, or oxidative stress of hatchlings. There was evidence of sex-specific effects in the thyroid system responses to the BTBPE exposures, with type 2 deiodinase (D2) activity decreasing at higher doses in female, but not in male hatchlings, suggesting that females may be more sensitive to BTBPE. However, there were no effects of TBBPA-BDBPE on the thyroid system in kestrels. For the BTPBE study, a subset of high-dose eggs was collected throughout the incubation period to measure changes in BTBPE concentrations. There was no decrease in BTBPE over the incubation period, suggesting that BTBPE is slowly metabolized by kestrel embryos throughout their ∼28-d development. These two compounds, therefore, do not appear to be particularly toxic to embryos of the American kestrel.

Accumulation of pollutants in nestlings of an endangered avian scavenger related to territory urbanization and physiological biomarkers

We monitor pollutant accumulation and investigate associated changes at the physiological level within the population of an obligate avian scavenger, the Egyptian Vulture (Neophron percnopterus), from Catalonia (NE Spain). This population is expanding its range, presumably because of the use of human waste disposal sites as food resource. We hypothesized that habitat urbanization, presumably associated with feeding from human wastes, could influence the accumulation of persistent organic pollutants and metals. The aim of this study was to explore the relationship between accumulated pollutants and biochemical parameters in nestling blood. We used the proportion of urban surface within an 8 km radius of each nest as a proxy to study the relationship between anthropic influence and pollutant accumulation. Observed blood levels of metals, organochlorine pesticides, polychlorinated biphenyls (PCBs), per- and polyfluoroalkylated substances (PFAS) and polybrominated diphenyl ethers (PBDEs) were relatively low, as expected for nestling individuals due to short-term exposures. CB-180 and PBDEs were associated with variations in blood biochemistry parameters; hexa-BDEs appeared positively associated with activities of the enzymes aspartate aminotransferase and lactate dehydrogenase, whereas CB-180 accumulation was associated with an increased activity of creatine phosphokinase and elevated glutathione levels. Increased CB-180 levels were also related to decreased blood concentrations of calcium, cholesterol, α-tocopherol and lutein. A proportion of urban surfaces as low as 6.56% within a radius of 8 km around the nest appears related to the accumulation of CB-180, the majority of analysed PFAS and of PBDE congeners 99 and 209, and increased urbanization was also associated with decreased plasma levels of α-tocopherol and carotenoids. These associations suggest that changes in blood profiles of vitamins, carotenoids or other analytes, despite related to increased plasma levels of CB-180, would be consequence of exploitation of artificial food sources rather than of a direct effect of the pollutants.

Bioaccumulation of Selected Halogenated Organic Flame Retardants in Lake Ontario

The trophic magnification of polybrominated diphenyl ethers (PBDEs) and selected nonlegacy halogenated organic compounds (HOCs) was determined in the food web of Lake Ontario (ON, Canada). In all, 28 Br₃ -Br₈ -PBDEs and 24 HOCs (10 of which had not been targeted previously) were analyzed. Average concentrations of Σ₂₈ PBDEs in fish ranged between 79.7 ± 54.2 ng/g lipid weight in alewife (Alosa pseudoharengus) and 815 ± 695 ng/g lipid weight in lake trout (Salvelinus namaycush). For invertebrates, concentrations were between 13.4 ng/g lipid weight (net plankton; >110 μm) and 41.9 ng/g lipid weight in Diaporeia (Diaporeia hoyi). Detection frequency (DF) for HOCs was highest for anti-Dechlorane Plus (anti-DDC-CO), 1,3-diiodobenzene (1,3-DiiB), tribromo-methoxy-methylbenzene (ME-TBP), allyl 2,4,6-tribromophenyl ether (TBP-AE), pentabromocyclododecene (PBCYD), α+β-tetrabromocylcooctane (TBCO), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE), and pentabromotoluene (PBT; DF for all = 100% in lake trout). Tetrabromoxylene (TBX), dibromopropyl 2,4,6-tribromophenyl ether (TBP-DBPE), and syn-DDC-CO were also frequently detected in trout (DF = 70-78%), whereas 2,3,4,5,6-pentabromoethyl benzene (PBEB) was detected only in plankton. Several HOCs were reported in aquatic biota in the Great Lakes (USA/Canada) for the first time in the present study, including PBCYD, 1,3DiiB, BATE, TBP-DBPE, PBT, α + β-TBCO, and ME-TBP. The Br_4-6 -BDEs (-47, -85, -99, -100, -153, and -154) all had prey-weighted biomagnification factors (BMF_PW ) values >6, whereas BMF_PW values for Br_7-8 -BDEs were <1. The highest BMF_PW values of non-PBDEs were for TBP-DBPE (10.6 ± 1.34) and ME-TBP (4.88 ± 0.60), whereas TBP-AE had a BMF_PW value of <1. Significant (p ≤ 0.05) trophic magnification factors (TMFs), both positive and negative, were found for Br_4-8- BDEs (BDE 196 = 0.4; BDE 154 = 9.5) and for bis(2,4,6-tribromophenoxy)ethane (BTBPE; 0.53), PBCYD (1.8), 1,3-DiiB (0.33), and pentabromobenzene (PBB; 0.25). Food chain length was found to have a significant influence on the TMF values. Environ Toxicol Chem 2019;38:1198-1210. © 2019 SETAC.

Flame retardant concentrations and profiles in wild birds associated with landfill: A critical review

Given factors such as their persistence and toxicity, legacy brominated flame retardants (BFRs) like polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD), are designated as persistent organic pollutants (POPs) and are subject to regulation. Waste streams likely represent a substantial reservoir of legacy BFRs given that they were once widely applied to goods which are increasingly likely to be obsolete. Waste streams are also increasingly likely to be a source of emerging flame retardants, in particular, novel BFRs (NBFRs), the halogenated norbornene flame retardant Dechlorane Plus (DDC-CO) and the brominated, chlorinated or non-halogenated organophosphate triester flame retardants (PFRs). Many bird populations rely on landfill and its surrounding land-use for inter alia the opportunities it provides for activities such as foraging and resting. However, studies on captive and wild (free-living) birds have demonstrated deleterious effects of several FRs. Globally, approximately 250 bird species, including many of conservation concern, are reported to use landfill and surrounding habitat (including wastewater treatment operations), thus putting birds potentially at risk of exposure to such chemicals. We synthesise and critically evaluate a total of 18 studies covering eight avian species published between 2008 and 2018 (inclusive) across four continents that report flame retardant (FR) burdens in birds utilising landfill. Several such studies found FRs at among the highest concentrations detected in wild biota to date. We recommend that ongoing research be focused on landfill-associated birds, given that landfill is an important source of FRs and other anthropogenic chemicals, and particularly at sites where species are of conservation concern. We suggest ways in which the comparative power of studies could be enhanced in the future, the reporting of a minimum common suite of key chemicals, and where feasible, standardisation of the tissue compartments (i.e., eggs) to be studied. We conclude by identifying future research directions.

Changes in thyroid function of nestling tree swallows (Tachycineta bicolor) in relation to polycyclic aromatic compounds and other environmental stressors in the Athabasca Oil Sands Region

In the Canadian Athabasca Oil Sands Region (AOSR), nestling tree swallows (Tachycineta bicolor) raised near mining-related activities accumulated greater concentrations of polycyclic aromatic compounds (PACs) that contributed to their poorer condition, growth, and reproductive success. Here, we report changes in thyroid function of the same 14 day old (do) nestlings (N ≤ 68) at these mining-related sites (OS1, OS2) compared to reference nestlings (REF1), and in relation to multiple environmental stressors that influence avian thyroid function. Thyroid function was compromised for OS1 nestlings but generally comparable between OS2 and REF1 chicks. In 2012, circulating total triiodothyronine (TT3) and thyroxine (TT4) were similar among all nestlings. The OS1 chicks had more active thyroid glands based on histological endpoints. Hepatic T4 outer-ring deiodinase (T4-ORD) activity was suppressed in OS1 and OS2 chicks. Despite inter-annual differences, OS1 chicks continued experiencing compromised thyroid function with significantly higher circulating TT4 and more active thyroid glands in 2013. The OS2 chicks had less active thyroid glands, which conceivably contributed to their suppressed growth (previously reported) relative to the heavier OS1 nestlings with more active thyroid glands. Thyroid gland activity was more influenced by the chicks' accumulation of (muscle), than exposure (feces) to naphthalene, C2-naphthalenes, and C1-fluorenes. Of four major volatile organic contaminants, sulfur dioxide (SO₂) primarily influenced thyroid gland activity and structure, supporting previous findings with captive birds. When collectively considering environmental-thyroidal stressors, chicks had a greater thyroidal response when they experienced colder temperatures, accumulated more C2-naphthalenes, and consumed aquatic-emerging insects with higher PAC burdens than terrestrial insects (carbon (δ¹³C)). We hypothesize that the more active thyroid glands and higher circulating TT4 of the OS1 chicks supported their growth and survival despite having the highest PAC burdens, whereas the lack of thyroid response in the OS2 chicks combined with high PAC burdens, contributed to their smaller size, poorer condition and poorer survival.

Is the urban-adapted ring-billed gull a biovector for flame retardants?

Birds may act as biovectors of nutrients and contaminants at the regional scale and potentially increase the exposure to such substances in ecosystems frequented by these birds. However, no study has estimated biotransport of contaminants by individual birds through their feces (guano). Elevated concentrations of halogenated flame retardants (HFRs) have been reported in ring-billed gulls (Larus delawarensis) breeding near Montreal (QC, Canada)- a known hotspot for HFRs. The objective of the present study was to investigate the concentrations of polybrominated diphenyl ethers (PBDEs) and selected emerging HFRs (e.g., Dechlorane-related compounds) in guano of individual ring-billed gulls, and to assess the relative accumulation of these HFRs by comparing concentrations in plasma (absorbed) versus guano (excreted). A second objective was to determine the importance of one of the largest ring-billed gull colony (Deslauriers Island) in North America located near Montreal as a vector of HFR biotransport at the regional scale. Elevated concentrations of PBDEs and Dechlorane plus were determined in guano and plasma of ring-billed gulls, although in general no difference was found between males and females. However, plasma to guano concentration ratios were significantly greater in females for the highly hydrophobic BDE-209 and Dechlorane plus compared to males. Overall, for both sexes combined, the total amount of HFRs (sum of the 16 major PBDEs and five emerging HFRs) deposited by this entire colony (64,980 gulls) in the Montreal area through guano during the 28-days incubation period was estimated to 1 g. This study showed that urban-adapted ring-billed gulls from this large colony represent an underestimated biovector of HFRs, which may contribute to augment exposure to these toxic compounds in nearby ecosystems.

Sex-specific responses in neuroanatomy of hatchling American kestrels in response to embryonic exposure to the flame retardants bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate

Bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (BEH-TEBP) and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), flame retardant components of FireMaster 550® and 600® have been detected in tissues of wild birds. To address the paucity of information regarding potential impacts of flame retardants on the brain, brain volume regions of hatchling American kestrels (Falco sparverius) were evaluated following in ovo injection at embryonic day 5 with safflower oil or to 1 of 3 doses of either BEH-TEBP (12, 60, or 107 ng/g egg) or EH-TBB (11, 55, or 137 ng/g egg). The doses for both chemicals reflected concentrations reported in wild birds. The volumes of the hippocampus and telencephalon and volumetric differences between left and right hemispheres were measured in hatchlings (embryonic day 28). A sex-specific effect of BEH-TEBP on relative hippocampus volume was evident: the hippocampus was significantly enlarged in high-dose females compared to control females but smaller in low-dose females than the other females. There was no significant effect of EH-TBB on hippocampus volume in female kestrel hatchlings or of either chemical in male hatchlings and no effects of these concentrations of EH-TBB or BEH-TEBP on telencephalon volume or the level of symmetry between the hemispheres of the brain. In sum, embryonic exposure of female kestrels to these BEH-TEBP concentrations altered hippocampus volume, having the potential to affect spatial memory relating to ecologically relevant behavior such as prey capture, predator avoidance, and migration. Environ Toxicol Chem 2018;37:3032-3040. © 2018 SETAC.

Reproductive and developmental changes in tree swallows (Tachycineta bicolor) are influenced by multiple stressors, including polycyclic aromatic compounds, in the Athabasca Oil Sands

Mining in the Athabasca Oil Sands Region (AOSR) has contributed extensively to increased exposure of wildlife to naturally occurring polycyclic aromatic compounds (PACs), yet little is known about the toxicity of PACs to wildlife in this region. We identified reproductive and developmental changes in tree swallows (Tachycineta bicolor) breeding in close proximity to mining-related activities in the AOSR, and determined these changes in relation to the birds' exposure and accumulation of 41 PACs (parent-, alkylated-PAHs), dibenzothiophenes (DBTs; previously published), diet (carbon (δ¹³C), nitrogen (δ¹⁵N)), volatile organic compounds, and weather variables. Tree swallow pairs (N = 43) were compared among mining-related (OS1, OS2) and reference (REF1, REF2) sites. At OS2, clutch initiation was slightly advanced (2012) but reproductive success (65%) was much lower than at the other sites (≥ 79%). Fledgling production by each pair was influenced by the timing of clutch initiation (years combined); in a highly inclement brood rearing period (2013), additional influences included the nestlings' exposure to ΣDBTs, accumulation of C1-naphthalene, the trophic position of the prey in their diet (δ¹⁵N), and record-breaking rainfall. Nestlings at OS2 were significantly lighter at day (d) 9 and d14, and in poorer body condition (d9). Nestling body mass was influenced by multiple stressors that varied by site: mass of younger nestlings (d9) was related to dietary source (δ¹³C; e.g., wetlands, terrestrial fields), exposure and/or accumulation of C1-phenanthrenes, C2-fluorenes, Σalkyl-PAHs and ΣDBTs, while for older nestlings (d14), body mass was related to sex, hatch date and/or rainfall during brood rearing. The swallows' exposure and accumulation of parent-PACs, alkyl-PACs and DBTs, the timing of hatching, their diet and exposure to highly inclement rains, contributed to their reproductive and developmental changes.

Elevated exposure, uptake and accumulation of polycyclic aromatic hydrocarbons by nestling tree swallows (Tachycineta bicolor) through multiple exposure routes in active mining-related areas of the Athabasca oil sands region

In the Athabasca Oil Sands (OS) Region, the exposure (by air, water, diet), uptake and deposition of polycyclic aromatic compounds (PACs), including parent and alkylated hydrocarbons (PAHs) and dibenzothiophenes (DBTs), was assessed in nestling tree swallows (Tachycineta bicolor) at mining-related (OS1, OS2) and reference (REF) sites. The OS sites did not receive oil-sands processed waters (OSPW) and were ≥60km from the reference sites. Most of the 42 PACs (≤98%) were detected in all matrices. Swallows at the OS sites were exposed to higher air and water concentrations of individual PAC congeners, ΣPACs, Σparent-PAHs, Σalkyl-PAHs and ΣDBTs. Compared to reference nestlings (ΣPACs: 13-27ng/g wet weight (ww)), PACs were significantly higher in OS nestlings (31-106ng/gww) that also accumulated higher concentrations of major PAHs (i.e., naphthalene, C1-naphthalene, C2-naphthalene, C1-fluorenes, C2-fluorenes, C1-phenanthrenes) measured in 60% of nestlings. Uptake and deposition of PAHs in the birds' muscle was related to diet (δ¹⁵N: C1-naphthalenes, C2-naphthalenes, C1-fluorenes), water (C1-phenanthrenes), and air through inhalation and feather preening (C1-fluorenes), but fecal concentrations were not well explained by diet or environmental concentrations. While PAH concentrations were much higher in muscle than feces, they were highly correlated (p≤0.001 for all). Thus feces may represent a non-lethal method for characterizing PAH exposure of birds, with muscle characterizing accumulation and sources of PAH exposure. Tree swallows in the Athabasca OS Region are exposed to many PACs, accumulating higher concentrations when developing in close proximity to mining activity through diet, aerial deposition and mining-impacted freshwater sources (e.g., wetlands).

Organophosphate esters in East Greenland polar bears and ringed seals: Adipose tissue concentrations and in vitro depletion and metabolite formation

East Greenland is a contamination "hot spot" for long-range transported anthropogenic chemicals, including organophosphate esters (OPEs). High concentrations of OPEs have been reported in arctic air while very little is known for wildlife where OPE tissue residues levels appear to be strongly influenced by biotransformation. In the present study, the hepatic in vitro metabolism of six environmentally relevant organophosphate (OP) triesters and corresponding OP diester formation were investigated in East Greenland polar bears (PBs) and ringed seals (RSs). The in vitro metabolism assay results were compared to adipose levels in field samples from the same individuals. In vitro OP triester metabolism was generally rapid and structure-dependent, where PBs metabolized OPEs more rapidly than RSs. Exceptions were the lack of triethyl phosphate (TEP) metabolism and slow metabolism of tris(2-ethylhexyl) phosphate (TEHP) in both species. OP diester metabolites were also formed with the exception of TEP which was not metabolized at all. Tris(1,3-dichloro-2-propyl) phosphate was completely converted to its corresponding diester. However, the mass balances showed that OP diester formation corresponding to TEHP, tri(n-butyl) phosphate, and tris(2-butyoxyethyl) phosphate did not account for 100% of the OP triester depletion, which indicated alternate pathways of OP triester metabolism had occurred. Triphenyl phosphate was completely converted to its OP diester metabolite in PBs but not in RSs suggesting species-specific differences. The results demonstrated that OP triester bioaccumulation and fate in PBs versus their RS prey is substantially influenced by biotransformation.

Waste-water treatment plants are implicated as an important source of flame retardants in insectivorous tree swallows (Tachicyneta bicolor)

Wastewater treatment plants (WWTPs) are an important source of anthropogenic chemicals, including organic flame retardants (FRs). Limited studies indicate birds can be exposed to FRs by feeding from waters receiving WWTP effluent or in fields receiving biosolids. Expanding on our earlier study, 47 legacy and 18 new FR contaminants were characterized in the eggs of insectivorous tree swallows (Tachycineta bicolor) feeding in water bodies receiving effluent from two WWTPs and compared to those from a reference site 19 km downstream of the nearest WWTP. Of the FRs measured, polybrominated diphenyl ethers (PBDEs) dominated the FR profile, specifically BDE-47, -99, -100, -153, -154, with considerably lower concentrations of hexabromocyclododecane (HBCDD), BDE-183 and BDE-209; each detected in 96-100% of the eggs overall except HBCDD (83%). FR concentrations were usually significantly greater in eggs from the secondary WWTP versus the tertiary WWTP and/or reference site. Despite low detection rates, concentrations of new FRs, specifically pentabromobenzyl acrylate (PBBA), 1,2,-bis-(2,4,6-tribromophenoxy)ethane (BTBPE), bis(2-ethylhexyl)-tetrabromophthalate (BEHTBP), tetrabromo-o-chlorotoluene (TBCT), hexabromobenzene (HBB), α- and β-1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (DBE-DBCH), were greater than HBCDD or BDE-209. Additional evidence that WWTPs are an important source of exposure to new FR contaminants for birds utilizing associated water bodies is that only the WTTP eggs, not the reference eggs, had measureable concentrations of PBBA, TBCT, BEHTBP, HBB, α-DBE-DBCH, 2,2',4,5,5'-pentabromobiphenyl (BB-101), pentabromoethyl benzene (PBEB), 2,4,6-tribromophenyl allyl ether (TBPAE), and tetrabromo-p-xylene (pTBX). Our study suggests that WWTPs are an important source of legacy and new FR contaminants for birds consuming prey that are associated with WWTP out-flows.

Regulated and Unregulated Halogenated Flame Retardants in Peregrine Falcon Eggs from Greenland

Median levels of regulated flame retardants, i.e., polybrominated diphenyl ethers (PBDEs), brominated biphenyl (BB)-153, and hexabromocyclododecane (HBCD), in 33-48 eggs of peregrine falcons (Falco peregrinus) from Greenland were 1909, 359, and 5.98 ng/g lipid weight (lw), respectively, and generally intermediate to levels in North America and Europe. Unregulated flame retardants had lower median concentrations of 1.06 (2-ethylhexyl-2,3,4,5-tetrabromobenzoate, EH-TBB), 2.42 (1,2-bis(2,4,6-tribromophenoxy)-ethane, BTBPE), 0.52 (2,4,6-tribromophenyl 2,3-dibromopropyl ether, DPTE), and 4.78 (dechlorane plus) ng/g lw. Although these compounds are often described as recent replacements for PBDEs, they were also present in eggs from the 1980s. BDE-209 was the only compound with a significant increase (+7.2% annual change) between 1986 and 2014, while BB-153 and DPTE decreased significantly (-8.0% and -2.8% annual change, respectively). Dechlorane plus showed a nonsignificant increase. Individual birds, equipped with light-logging geolocators, confirmed the contaminant exposure over a large geographical area as the birds spent nearly equal time periods in their breeding and wintering grounds in Greenland and Central/South America, respectively, interrupted by 5-6 weeks of migration through North America.