Dietary exposure of American kestrels (Falco sparverius) to decabromodiphenyl ether (BDE-209) flame retardant: uptake, distribution, debromination and cytochrome P450 enzyme induction

Dynamics and effects of plastic contaminants' assimilation in gulls

Polybrominated diphenyl ethers are persistent disrupters assimilated by organisms, yet little is known about their link to plastic ingestion and health effects. In an experiment, two groups of yellow-legged/lesser black-backed gulls (Larus michahellis/Larus fuscus) were fed plastics with BDE99 to assess leaching into brain, preen oil, liver and fat tissues and evaluate effects on health and stress parameters. Although most plastic was regurgitated, we observed a clear relation between plastic ingestion and chemical leaching. BDE99 exhibited higher levels in brain tissue of gulls from the plastic groups. Also, only values of cholinesterases measured in plasma were significantly reduced in the 'plastic' groups. Cholinesterase activity in the brain also tended to decrease, suggesting a negative effect in gulls' neurofunction. Results indicate that chemical leaching occurs, even when plastics stay in the stomach for a short period of time and showed that this can affect gulls' health.

Trophic Transfer of Halogenated Organic Pollutants in a Wetland Food Web: Insights from Compound-Specific Nitrogen Isotope of Amino Acids and Food Source Analysis

A trophic position (TP) model (TPmix model) that simultaneously considered trophic discrimination factor and βGlu/Phe variations was developed in this study and was first applied to investigate the trophic transfer of halogenated organic pollutants (HOPs) in wetland food webs. The TPmix model characterized the structure of the wetland food web more accurately and significantly improved the reliability of TMF compared to the TPbulk, TPAAs, and TPsimmr models, which were calculated based on the methods of stable nitrogen isotope analysis of bulk, traditional AAs-N-CSIA, and weighted βGlu/Phe, respectively. Food source analysis revealed three interlocking food webs (kingfisher, crab, and frogs) in this wetland. The highest HOP biomagnification capacities (TMFmix) were found in the kingfisher food web (0.24-82.0), followed by the frog (0.08-34.0) and crab (0.56-11.7) food webs. The parabolic trends of TMFmix across combinations of log KOW in the frog food web were distinct from those of aquatic food webs (kingfisher and crab), which may be related to differences in food web composition and HOP bioaccumulation behaviors between aquatic and terrestrial organisms. This study provides a new tool to accurately study the trophic transfer of contaminants in wetlands and terrestrial food webs with diverse species and complex feeding relationships.

Novel and legacy brominated flame retardants in snakes and frogs: Tissue distribution, biomagnification, and maternal transfer

Although many studies have examined polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs) in biota, information on the bioaccumulation characteristics of NBFRs from field works is limited. This study investigated the tissue-specific exposure to PBDEs and NBFRs in two reptilian (short-tailed mamushi and red-backed rat snake) and one amphibian species (black-spotted frog) prevalent in the Yangtze River Delta, China. The levels of ΣPBDEs and ΣNBFRs ranged from 4.4-250 and 2.9-22 ng/g lipid weight for snakes respectively and 2.9-120 and 7.1-97 ng/g lipid weight for frogs respectively. BDE-209, BDE-154, and BDE-47 were three major PBDE congeners while decabromodiphenylethane (DBDPE) dominated in NBFRs. Tissue burdens indicated that snake adipose was the major storage site of PBDEs and NBFRs. The biomagnification factors (BMFs) estimated from black-spotted frog to red-backed rat snake indicated the biomagnification of penta- to nona-BDE congeners (BMFs 1.1-4.0) but the lack of biomagnification of other BDE and all NBFR congeners (BMFs 0.16-0.78). Mother to egg transfer of PBDEs and NBFRs evaluated in frogs showed that maternal transfer efficiency was positively related to chemical lipophilicity. This is the first field study on the tissue distribution of NBFRs in reptiles and amphibians and the maternal transfer behavior of 5 major NBFRs. The results underline the bioaccumulation potential of alternative NBFRs.

Legacy and novel brominated flame retardants in a lab-constructed freshwater ecosystem: Distribution, bioaccumulation, and trophic transfer

The extensive utilization of both legacy and novel brominated flame retardants (BFRs) leads to high environmental concentrations, which would be bioaccumulated by organisms and further transferred through the food webs, causing potential risks to humans. In this study, five BFRs, that showed high detection frequencies and concentrations in sediments from an e-waste dismantling site in Southern China, namely 2,3,4,5,6-pentabromotoluene (PBT), hexabromobenzene (HBB), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), decabromodiphenyl ethane (DBDPE), and decabromodiphenyl ether (BDE209), were selected as target pollutants in the lab-constructed aquatic food web as part of a micro-ecosystem, to investigate their distribution, bioaccumulation, and trophic transfer patterns. The significant correlations between different samples in the food web indicated that the dietary uptake appeared to influence the levels of BFRs in organisms. Significant negative correlations were observed between the trophic level of organisms and the lipid-normalized concentrations of BTBPE and DBDPE, indicating the occurrence of trophic dilution after 5-month exposure. However, the average values of bioaccumulation factors (BAFs) were from 2.49 to 5.17 L/kg, underscoring the importance of continued concern for environmental risks of BFRs. The organisms occupying higher trophic levels with greater bioaccumulation capacities may play a pivotal role in determining the trophic magnification potentials of BFRs. This research provides a helpful reference for studying the impacts of feeding habits on bioaccumulation and biomagnification, as well as for identifying the fate of BFRs in aquatic environment.

N-acetylcysteine rescues meiotic arrest during spermatogenesis in mice exposed to BDE-209

Deca-bromodiphenyl ethers (BDE-209) has been widely used in electronic devices and textiles as additives to flame retardants. Growing evidence showed that BDE-209 exposure leads to poorer sperm quality and male reproductive dysfunction. However, the underlying mechanisms of BDE-209 exposure caused a decline in sperm quality remains unclear. This study aimed to evaluate the protective effects of N-acetylcysteine (NAC) on meiotic arrest in spermatocytes and decreased sperm quality in BDE-209-exposed mice. In the study, mice were treated with NAC (150 mg/kg BW) 2 h before administrated with BDE-209 (80 mg/kg BW) for 2 weeks. For the in vitro studies, spermatocyte cell line GC-2spd cells were pretreated with NAC (5 mM) 2 h before treated with BDE-209 (50 μM) for 24 h. We found that pretreatment with NAC attenuated the oxidative stress status induced by BDE-209 in vivo and in vitro. Moreover, pretreatment with NAC rescued the testicular histology impairment and decreased the testicular organ coefficient in BDE-209-exposed mice. In addition, NAC supplement partially promoted meiotic prophase and improved sperm quality in BDE-209-exposed mice. Furthermore, NAC pretreatment effectively improved DNA damage repair by recovering DMC1, RAD51, and MLH1. In conclusion, BDE-209 caused spermatogenesis dysfunction related to the meiotic arrest medicated by oxidative stress, decreasing sperm quality.

Aerobic Degradation Characteristics and Mechanism of Decabromodiphenyl Ether (BDE-209) Using Complex Bacteria Communities

Complex bacteria communities that comprised Brevibacillus sp. (M1) and Achromobacter sp. (M2) with effective abilities of degrading decabromodiphenyl ether (BDE-209) were investigated for their degradation characteristics and mechanisms under aerobic conditions. The experimental results indicated that 88.4% of 10 mg L^-1 BDE-209 could be degraded after incubation for 120 h under the optimum conditions of pH 7.0, 30 °C and 15% of the inoculation volume, and the addition ratio of two bacterial suspensions was 1:1. Based on the identification of BDE-209 degradation products via liquid chromatography-mass spectrometry (LC-MS) analysis, the biodegradation pathway of BDE-209 was proposed. The debromination, hydroxylation, deprotonation, breakage of ether bonds and ring-opening processes were included in the degradation process. Furthermore, intracellular enzymes had the greatest contribution to BDE-209 biodegradation, and the inhibition of piperyl butoxide (PB) for BDE-209 degradation revealed that the cytochrome P450 (CYP) enzyme was likely the key enzyme during BDE-209 degradation by bacteria M (1+2). Our study provided alternative ideas for the microbial degradation of BDE-209 by aerobic complex bacteria communities in a water system.

Toxicokinetics and edible tissues-specific bioaccumulation of decabrominated diphenyl ethers (BDE-209) after exposure to the broilers

Decabromodiphenyl ether (BDE-209), the primary constituent of a widely used flame retardant formulation, is often present in high levels in avian derived products and could be transferred to humans through consumption. The purpose of this study was to investigate the toxicokinetics and bioaccumulation patterns of BDE-209 in different tissues of broilers, which would benefit the evaluation of chicken product safety. Male broilers received a single oral administration of BDE-209 at 25 mg/kg.BW and then BDE-209 concentrations in the plasma, liver, leg muscle, breast muscle, and other tissues were measured using gas chromatography-electron capture detection (GC-ECD). The changes of BDE-209 concentrations in the plasma were fitted to a non-compartmental model for kinetic analysis. Peak values were observed at 24 h (t_1/2 =168.28 h), and trace levels remained for four weeks. Additionally, C_max in the liver was much higher than that in leg and breast muscles, and T_max from the liver and muscle were 12 and 24 h, respectively. Residual BDE-209 was detected in all broiler tissues after 2 weeks, and concentrations were ranked as follows: fat > liver > thymus gland > heart > testis > thigh muscle > skin > lung > kidney > breast muscles > spleen (wet weight (ww)). Our results suggested that BDE-209 was widely distributed in different tissues after intestinal absorption, and preferentially accumulated in adipose and liver tissues. Observations of bioaccumulation and slow elimination in the liver and muscles provide critical insight into the toxicity of BDE-209 and risk assessment of edible tissues from broilers.

Biotransformation of Dec-604 and potential effect on thyroid deiodinase activity in highly flame retardant-exposed gulls

Several halogenated flame retardants (HFRs) have been identified as thyroid disruptors in birds including the polybrominated diphenyl ether (PBDE) mixtures, which have been replaced with other HFRs such as Dechlorane-604 (Dec-604). Dec-604 Component B (Dec-604 CB), a putative debrominated product of Dec-604, has been frequently reported in urban-adapted ring-billed gulls (Larus delawarensis) breeding in the Montreal area (QC, Canada). The metabolic pathways of Dec-604 are yet to be characterized, although the occurrence of Dec-604 CB in gulls may suggest that enzyme-mediated dehalogenation may occur, potentially involving the thyroid deiodinases. The objective of this study was to investigate the effect of Dec-604 on type 1 deiodinase (DIO1) in the presence of thyroxine (T₄) in an in vitro DIO1 assay using liver microsomes of ring-billed gulls that are highly exposed to HFRs in the Montreal area, and to determine whether DIO1 is involved in the in vitro debromination of Dec-604. We tested the in vitro activity of DIO1 in gull liver microsomes in the presence of five concentrations of Dec-604 ranging from 0.86 to 86.21 nM. HFR concentrations (Σ₄₀HFR) were also determined in liver samples of gulls. Results showed that total DIO1 activity in gull liver microsomes was increased by three of the five concentrations of Dec-604. No relationship between liver Σ₄₀HFR concentrations and DIO1 activity was observed, except for T₂ formation rates that significantly decreased with increasing liver HFR concentrations. Moreover, greater Dec-604 CB to Dec-604 concentration ratios in activated gull microsomes (with the DIO1 cofactor dithiothreitol) were found at the intermediate Dec-604 concentration compared to controls. These results suggested that liver microsome DIO1 activity may be perturbed in ring-billed gulls exposed to Dec-604, and be involved at least in part, in the debromination of Dec-604 leading to the formation of Dec-604 CB.

A Pilot Study on the Concentration, Distribution and Bioaccumulation of Polybrominated Diphenyl Ethers (PBDEs) in Tissues and Organs of Grassland Sheep

Polybrominated diphenyl ether (PBDE) concentrations in various tissues and organs of grassland sheep from Inner Mongolia, China, were determined. The abilities of PBDEs binding to ovine serum albumin (OSA) and Cytochrome P450 enzyme (CYP3A24) were assessed by fluorescence spectroscopy and molecular docking simulations. The PBDE concentrations in the sheep tissue and organ samples were 33.4-167 pg/g dw. The distribution of PBDEs in sheep organs and tissues is affected not only by the function of organs and tissues, but also by the characteristics of PBDEs. Adipose tissue tends to bioaccumulate more-brominated BDEs (BDE-154, -153, and -183), but muscle tissues and visceral organs mainly bioaccumulate less-brominated BDEs. The distribution of PBDEs in visceral organs is mainly affected by the transport of ovine serum albumin (OSA) and the metabolism of CYP3A24 enzyme. The distribution of PBDEs in adipose tissue and brain is mainly affected by their logK_OW.

Metabolic transformation of environmentally-relevant brominated flame retardants in Fauna: A review

Over the past few decades, production trends of the flame retardant (FR) industry, and specifically for brominated FRs (BFRs), is for the replacement of banned and regulated compounds with more highly brominated, higher molecular weight compounds including oligomeric and polymeric compounds. Chemical, biological, and environmental stability of BFRs has received some attention over the years but knowledge is currently lacking in the transformation potential and metabolism of replacement emerging or novel BFRs (E/NBFRs). For articles published since 2015, a systematic search strategy reviewed the existing literature on the direct (e.g., in vitro or in vivo) non-human BFR metabolism in fauna (animals). Of the 51 papers reviewed, and of the 75 known environmental BFRs, PBDEs were by far the most widely studied, followed by HBCDDs and TBBPA. Experimental protocols between studies showed large disparities in exposure or incubation times, age, sex, depuration periods, and of the absence of active controls used in in vitro experiments. Species selection emphasized non-standard test animals and/or field-collected animals making comparisons difficult. For in vitro studies, confounding variables were generally not taken into consideration (e.g., season and time of day of collection, pollution point-sources or human settlements). As of 2021 there remains essentially no information on the fate and metabolic pathways or kinetics for 30 of the 75 environmentally relevant E/BFRs. Regardless, there are clear species-specific and BFR-specific differences in metabolism and metabolite formation (e.g. BDE congeners and HBCDD isomers). Future in vitro and in vivo metabolism/biotransformation research on E/NBFRs is required to better understand their bioaccumulation and fate in exposed organisms. Also, studies should be conducted on well characterized lab (e.g., laboratory rodents, zebrafish) and commonly collected wildlife species used as captive models (crucian carp, Japanese quail, zebra finches and polar bears).

Species-specific debromination of BDE99 in teleost fish: The relationship between debromination ability and bioaccumulation patterns of PBDEs

Polybrominated diphenyl ethers (PBDEs) are known to be broken down by debromination reactions in the natural environment, such as by photolysis, microbial and metabolic processes. Although species-specific debromination of PBDEs by fish has also been reported, it has only rarely been studied from the phylogenetic perspective. The objective of this study is to reveal the factors affecting species-specific debromination through validation between the bioaccumulation of PBDEs in muscle tissue and the ability to debrominate BDE99. As environmental observations, PBDE concentrations in muscle tissues were analyzed in 25 wild fish (Cyprinidae, Gobiidae and others). As in vitro experiments, debromination experiments were conducted using the hepatic microsomes of 21 fish species. Significant amounts of BDE99 were detected in almost none of the Cyprinidae. A relatively higher debromination ability was confirmed in the Cyprinidae in in vitro experiments. The Cyprinidae thus appears to be a family with high debromination ability. BDE99 has been detected in some goby species but not others. This pattern was also seen in in vitro experiments, suggesting that debromination ability is not consistent within the Gobiidae. In further quantitative comparisons, kinetic parameters such as K_m and v_max were determined for selected fish species. The common carp (Cyprinus carpio) and the Japanese crucian carp (Carassius cuvieri), both Cyprinidae, showed higher v_max values, whereas v_max values among three Gobiidae diverged widely. A comparison of field observations and in vitro experiments, revealed the bioaccumulation ratio of BDE99 to be affected by the BDE99 debromination ability of each fish species. This is the first report on classification of BDE99 accumulation ratio by debromination ability and a phylogenetic species comparison based on kinetic parameters for debromination reactions of PBDEs by fish.

Release, transformation, and risk factors of polybrominated diphenyl ethers from landfills to the surrounding environments: A review

Polybrominated diphenyl ethers (PBDEs) serve as brominated flame retardants when added to various products. When these products reach their end of life, a large amount of domestic waste containing PBDEs enters the landfills. Given their weak chemical bonds, they are easily affected by physical, chemical, and biological processes. These processes result in their release and the subsequent contamination of the surrounding soil, groundwater, and atmosphere, causing harm to humans and ecosystems. However, despite the progress made in the research of PBDEs over the years, understanding of the environmental behavior and fate of pollutants is still limited. With the development of cities, the release of PBDEs in old landfills will gradually increase the risk to the surrounding environment. Here we review the biological and nonbiological transformation of PBDEs and their derivatives in landfills and surrounding areas, as well as their distribution in soil, groundwater, and atmosphere. Specifically, this review aims to provide insights into the following aspects: 1) the biological (plant, animal, and microbial) and nonbiological (metal catalysis and photodegradation) conversion of PBDEs and their derivatives in landfills and surrounding areas; 2) the distribution of landfill-sourced PBDEs in the soil, groundwater, atmosphere and cross-media migration; and 3) suggestions and future research directions for the management and control of PBDEs in landfills.

Bioaccumulation, elimination and metabolism in earthworms and microbial indices responses after exposure to decabromodiphenyl ethane in a soil-earthworm-microbe system

As a novel brominated flame retardant (NBFR), decabromodiphenyl ethane (DBDPE) has been poorly understood for the environmental fate and toxicity in terrestrial invertebrates. For the first time, the bioaccumulation, elimination, metabolism and detoxification of DBDPE in earthworms as well as its potential impacts on soil microbes were investigated. The results showed much higher DBDPE concentrations in casts than in earthworms. The bioaccumulation factor (BAF) and elimination rate constant (k_e) values were 0.028-0.213 (gdw, worm/gdw, soil) and 0.323-0.452 (day^-1), respectively. The detoxifying enzymes (CYP450 and GST) could be induced by DBDPE within the range of exposure dosage, and the activities were significantly increased at 21 d (p < 0.05). The results were identified by GC-ECNI-MS, and it showed that at least eleven unknown peaks were separately observed in the earthworms, which were the biotransformation products of DBDPE in earthworms. Additionally, the damages, including skin shrinkage, setae impairment, and intercellular vacuolization, were clearly observed by SEM/TEM. Based on these data, DBDPE could accumulate in earthworms, yet, with low bioaccumulation ability. Moreover, DBDPE exposure resulted in minimal harmful impacts on microbial activities including microbial biomass C (MBC), Microbial basal respiration (MBR), Urease (US) activity and fluorescein diacetate hydrolase (FDA) activity (p < 0.05). Our findings would provide some essential information for interpreting the ecological risks of DBDPE in soil.

Ingested plastics in northern fulmars (Fulmarus glacialis): A pathway for polybrominated diphenyl ether (PBDE) exposure?

Although it has been suggested that plastic may act as a vector for pollutants into the tissue of seabirds, the bioaccumulation of harmful contaminants, such as polybrominated diphenyl ethers (PBDEs), released from ingested plastics is poorly understood. Plastic ingestion by the procellariiform species northern fulmar (Fulmarus glacialis) is well documented. In this study, we measured PBDEs levels in liver tissue of northern fulmars without and with (0.13-0.43 g per individual) stomach plastics. PBDE concentrations in the plastic sampled from the same birds were also quantified. Birds were either found dead on beaches in southern Norway or incidentally caught in longline fisheries in northern Norway. PBDEs were detected in all birds but high concentrations were only found in liver samples from beached birds, peaking at 2900 ng/g lipid weight. We found that body condition was a significant factor explaining the elevated concentration levels in livers of beached birds. BDE209 was found in ingested plastic particles and liver tissue of birds with ingested plastics but was absent in the livers of birds without ingested plastics. This strongly suggests a plastic-derived transfer and accumulation of BDE209 to the tissue of fulmars, levels of which might prove useful as a general indicator of plastic ingestion in seabirds.

Bioaccumulation characteristics of PBDEs and alternative brominated flame retardants in a wild frog-eating snake

While a large body of studies have examined polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants (ABFRs) in wildlife, information on the bioaccumulation of these contaminants in reptiles in general, and snakes in particular, are scarce. We investigated the bioaccumulation characteristics of PBDEs and several ABFRs including decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB) and pentabromotoluene (PBT) in a frog-eating snake, the striped keelback snake (Amphiesma stolata), from an e-waste recycling site in South China. The concentrations of ∑PBDEs and ∑ABFRs in the snakes ranged 53-5200 and 3.1-87 ng/g lipid weight, respectively; with higher levels in males than females. Additionally, the concentrations of BDE-28, -47, and -66 were positively correlated with snake size (snout-vent length and body mass), while negative correlations were found for most of the higher brominated PBDE congeners and HBB, PBT and BTBPE. The biomagnification factors (BMFs) estimated in the snake/frog relationship indicated a mild to moderate biomagnification of BDE-28, -47, -66, -100, -153 and -154 (with mean BMFs of 1.1-5.3), while a lack of magnification for the other PBDE congeners and all the ABFRs. This is the first report on the sex- and size-related accumulation and biomagnification potentials of PBDEs and ABFRs in snakes.

Spatial distribution and hazard of halogenated flame retardants and polychlorinated biphenyls to common kingfisher (Alcedo atthis) from a region of South China affected by electronic waste recycling

Numerous studies have reported bioaccumulation of halogenated flame retardants (HFRs) and polychlorinated biphenyls (PCBs) in wildlife from electronic waste (e-waste) recycling sites. However, the concentrations and hazards of HFRs and PCBs in wildlife from non-e-waste sites which were not involved in any known e-waste recycling activities in the e-waste-impacted region are still unclear. Polybrominated diphenyl ethers (PBDEs), alternative HFRs (AHFRs; including dechlorane plus, decabromodiphenyl ethane, and 1,2-bis(2,4,6-tribromophenoxy) ethane), and PCBs were quantified in common kingfishers (Alcedo atthis) from a region affected by e-waste recycling in South China, and potential adverse effects were evaluated. Concentrations of ∑PBDEs and ∑PCBs in kingfishers ranged from 2.1 × 10³-1.3 × 10⁵ ng/g lipid mass (lm) and 2.1 × 10³-1.5 × 10⁶ ng/g lm, respectively. At e-waste recycling sites, these concentrations were 100- to 1000-fold greater than those in kingfishers from non-e-waste areas, where concentrations of ∑PBDEs and ∑PCBs were 16-1.2 × 10³ and 39-3.0 × 10³ ng/g lm, respectively. Concentrations of ∑AHFRs in kingfishers from e-waste sites and non-e-waste sites ranged from 8.5 to 3.6 × 10² and 0.8-2.9 × 10² ng/g lm, respectively. The greatest concentrations of PCBs in kingfishers were measured from the e-waste sites. Additionally, kingfishers from four non-e-waste sites in the vicinity of e-waste sites had greater PCB concentrations compared to the other six non-e-waste sites. Concentrations of AHFRs were negatively and significantly correlated with distance from an e-waste site, which indicated that AHFRs from non-e-waste sites might be influenced by point sources. Further, a significant (r² = 0.53, p = 0.02) positive correlation between human population density and concentrations of ∑PBDEs in kingfishers from non-e-waste sites was observed. Concentrations of either PBDEs or PCBs from e-waste sites might pose severe, adverse reproductive effects to kingfishers, while the potential for adverse effects of PBDEs and PCBs to kingfishers from most non-e-waste sites seemed minimal.

Mass balance study of brominated flame retardants in female captive peregrine falcons

Little is known about brominated flame retardant (BFR) dynamics in birds, especially large molecules such as decabromodiphenyl ether (BDE-209). In particular, bioaccumulation from food and transfer dynamics to eggs are poorly understood. Therefore, an input-output mass balance study of tri-decaBDEs, DBDPE and HBCDD was performed in three female peregrine falcons from a captive breeding program by analyzing their naturally contaminated food (quail, chicken (cockerels)), plasma, feces and eggs. Predominant BFRs in cockerels and quail were BDE-209 and DBDPE, as well as HBCDD in quail. The predominant BFRs found in falcon plasma were BDE-209, -153 and -183, in eggs, HBCDD, BDE-209 and -153 and in feces, BDE-209. Mean absorption efficiencies (AE) for the tetra-octabrominated BDEs ranged from 84-100% and 70% for HBCDD. The AEs for BDE-206, -207, -208 and -209 varied due to the large variability seen for feces fluxes. All egg/plasma ratios for BDEs were similar and greater than one (range 1.1-2.7), including for BDE-209, indicating efficient transfer from females to the eggs. Excretion via egg-laying was approximately 6.0-29% of the initial, pre-breeding body burden of individual penta-decaBDE congeners, (15-45% for BDE-206). HBCDD was not detected in plasma but was found in eggs, also indicating efficient transfer and excretion via eggs. Input fluxes from food exceeded the output fluxes (feces, eggs) indicating considerable metabolism for tetra-octaBDEs, possibly also for the nona-decaBDEs and HBCDD. Bioaccumulation factors calculated from lipid weight concentrations in plasma and food (BAFp) were highest for BDE-208 (31), -153 (23), -209 (19) and -207 (16) and from eggs and food (BAFe), were highest for HBCDD (140), BDE-153 (41), -208 (42), BDE-207 (24) and BDE-209 (21). BAFe and BAFp values were below 10 for BDE-47, -99 and -100. For one falcon, egg results were available from three different years and estimated half-lives were 65 d (BDE-99), 624 d (BDE-153), 31 d (BDE-154), 349 d (BDE-183), 77 d (BDE-196) and 89 d (BDE-197).

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.

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.

Distribution of polybrominated diphenyl ethers (PBDEs) in feather and muscle of the birds of prey from Beijing, China

Polybrominated diphenyl ethers (PBDEs) in the feather and muscle of common kestrels (Falco tinnunculus), eagle owls (Bubo bubo) and little owls (Athene noctua) collected from Beijing, China were investigated. The concentrations of ∑₂₃PBDEs in the muscle and feather of all the birds of prey ranged from 46 to 7.77 × 10⁴ ng/g lipid weight (lw; median 241 ng/g lw) and 1.50-191 ng/g dry weight (dw; median 21.1 ng/g dw), respectively. Higher brominated congeners, e.g., BDE-209, -153, -207 and -196 were the dominant congeners in both feather and muscle. However, the concentrations of lower brominated congeners in feather were significantly correlated with those in muscle (p < 0.05), which suggested that feather could efficiently reflect lower brominated BDEs in the internal tissue of birds of prey. The calculated hazard quotients (HQs) > 10 in common kestrel and little owl suggested that the high levels of PBDEs posed potentially high risk to some birds of prey living in Beijing area.

Unusually high Deca-BDE concentrations and new flame retardants in a Canadian Arctic top predator, the glaucous gull

Despite a sustained effort in surveying flame retardants (FRs) in wildlife from industrialized regions, their occurrence in birds or any other wildlife species spanning the Arctic regions, particularly in North America, has received limited attention. This study investigated in the top predator glaucous gull (Larus hyperboreus) breeding in the Eastern Canadian Arctic (Cape Dorset, Nunavut) a comprehensive suite of FRs including unstudied halogenated and non-halogenated FRs of potential health concern, along with legacy organochlorines and mercury. The influence of diet acquired locally and in wintering areas on the tissue contaminant profiles was also investigated using δ¹⁵N and δ¹³C signatures in liver and feathers. The principal constituent in the Deca-brominated diphenyl ether (BDE) mixture, BDE-209, was remarkably the most concentrated PBDE congener determined in liver samples of Eastern Canadian Arctic glaucous gulls. This suggests dietary exposure from the local marine food web and perhaps also from nearby community landfills. Moreover, this study revealed for the first time the presence of 16 emerging halogenated and non-halogenated FRs in glaucous gulls from this Arctic region including HBB, DDC-CO (anti and syn isomers), PBEB, EHTBB, BEHTBP as well as a series of organophosphate esters (OPEs) (TCEP, TCIPP, TPP, TDCIPP, TDBPP, TBNP, TBOEP, TBEP, TCrP, EHDPP, and TEHP). With the exception of BDE-209, concentrations of other halogenated FRs and organochlorines were found to be in the lower range in liver of Eastern Canadian Arctic glaucous gulls compared to individuals from other circumpolar populations (Svalbard and Greenland). Mercury and methylmercury concentrations, however, were greater than reported elsewhere for glaucous gull populations.

Interaction between deca-BDE and hepatic deiodinase in a highly PBDE-exposed bird

Studies have shown that debromination of the major component in the deca-brominated diphenyl ether mixture (deca-BDE), BDE-209, occurs in vivo in birds. Recent work from our laboratory on breeding ring-billed gulls (Larus delawarensis) exposed to elevated PBDE concentrations in the densely-populated metropolis of Montreal (Canada) further suggests that BDE-209 debromination is potentially catalyzed by deiodinases in liver microsomes. The first objective of this study was to determine if type 1 deiodinase (D1) was involved in the in vitro debromination of BDE-209 in liver microsomes of ring-billed gulls. The second objective was to determine if there was an interaction between D1 and BDE-209 using an in vitro D1 activity assay. No depletion of BDE-209 was observed in gull liver microsomes. A significant 42% increase in total D1 activity was found in gull liver microsomes at the medium BDE-209 concentration (1.0 nM), although not at the low (0.5 nM) or high (2.5 nM) concentrations, suggesting potential non-dose related interaction with D1. Moreover, no correlation was found between total D1 activity in liver microsomes and plasma thyroid hormone levels, although there was a negative relationship between plasma BDE-209 concentrations and FT₃ levels. Results from this study suggest that debromination of BDE-209 did not occur using present in vitro assay conditions, although indicated potential interaction with D1 that may have implication on circulating thyroid hormone status.

Bioaccumulation of Polybrominated Diphenyl Ethers and Alternative Halogenated Flame Retardants in a Vegetation-Caribou-Wolf Food Chain of the Canadian Arctic

The trophodynamics of halogenated flame retardants (HFRs) including polybrominated diphenyl ethers (PBDEs) and alternative HFRs were investigated in the terrestrial, vegetation-caribou-wolf food chain in the Bathurst Region of northern Canada. The greatest concentrations in vegetation (geometric mean of lichens, moss, grasses, willow, and mushrooms) were of the order 2,4,6-tribromophenyl allyl ether (TBP-AE) (10 ng g^-1 lw) > BDE47 (5.5 ng g^-1 lw) > BDE99 (3.9 ng g^-1 lw) > BDE100 (0.82 ng g^-1 lw) > 1,2,3,4,5-pentabromobenzene (PBBz) (0.72 ng g^-1 lw). Bioconcentration among types of vegetation was consistent, though it was typically greatest in rootless vegetation (lichens, moss). Biomagnification was limited in mammals; only BDE197, BDE206-208 and ∑PBDE biomagnified to caribou from vegetation [biomagnification factors (BMFs) = 2.0-5.1]. Wolves biomagnified BDE28/33, BDE153, BDE154, BDE206, BDE207, and ∑PBDE significantly from caribou (BMFs = 2.9-17) but neither mammal biomagnified any alternative HFRs. Only concentrations of BDE28/33, BDE198, nonaBDEs, and ∑PBDE increased with trophic level, though the magnitude of biomagnification was low relative to legacy, recalcitrant organochlorine contaminants [trophic magnification factors (TMFs) = 1.3-1.8]. Despite bioaccumulation in vegetation and mammals, the contaminants investigated here exhibited limited biomagnification potential and remained at low parts per billion concentrations in wolves.

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.

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

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

Biomagnification of persistent organic pollutants in a deep-sea, temperate food web

Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) were measured in a temperate, deep-sea ecosystem, the Avilés submarine Canyon (AC; Cantabrian Sea, Southern Bay of Biscay). There was an increase of contaminant concentration with the trophic level of the organisms, as calculated from stable nitrogen isotope data (δ¹⁵N). Such biomagnification was only significant for the pelagic food web and its magnitude was highly dependent on the type of top predators included in the analysis. The trophic magnification factor (TMF) for PCB-153 in the pelagic food web (spanning four trophic levels) was 6.2 or 2.2, depending on whether homeotherm top predators (cetaceans and seabirds) were included or not in the analysis, respectively. Since body size is significantly correlated with δ¹⁵N, it can be used as a proxy to estimate trophic magnification, what can potentially lead to a simple and convenient method to calculate the TMF. In spite of their lower biomagnification, deep-sea fishes showed higher concentrations than their shallower counterparts, although those differences were not significant. In summary, the AC fauna exhibits contaminant levels comparable or lower than those reported in other systems.

Absorption, tissue distribution, metabolism, and elimination of decabrominated diphenyl ether (BDE-209) in rats after multi-dose oral exposure

Human and ecological risks of BDE-209 have drawn much attention, particularly with growing e-waste recycling activities in developing countries. To further address the issue of BDE-209 biotransformation, a laboratory-controlled study was conducted. Female Sprague-Dawley rats were dosed orally by gavage at a daily dose of 1 mg kg^-1 body weight for 7 d and a depuration period of 22 d, to characterize absorption, distribution, metabolism, and elimination dynamics of BDE-209 during multi-dose exposures simulating short-term oral exposure of e-waste workers. The concentrations of BDE-209 in all tissues increased exponentially during the 7-d exposure period, indicating that multi-dose exposure could lead to increased accumulation of BDE-209 in rats. The liver accumulated the greatest amount of BDE-209 on a wet-weight basis, while adipose tissue had the highest concentration by the end of the 22-d depuration period. Half-lives of BDE-209, 207, and 197 during depuration were 1.1 ± 0.1, 2.7 ± 0.3, and 10.5 ± 3.1 d in serum and 0.9 ± 0.1, 2.2 ± 0.2, and 11.8 ± 2.3 d in liver, i.e., the half-life increased with decreasing level of bromination from deca- to octa-BDEs and was similar in both serum and liver. By contrast, the half-life of the debromination metabolite BDE-207 (21.7 ± 7.7 d) was longer in small intestine than in serum and liver, suggesting slower depletion of BDE-209 metabolites in small intestine. The metabolism of BDE-209 was not responsible for the occurrence of low brominated BDE congeners and OH and MeO-PBDEs in human tissues.

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

Flame retardants (FR) are industrial chemicals and some are proven environmental contaminants that accumulate in predatory birds. Few studies have examined the influence of diet on FR profiles in nestling raptors and the possible physiological implications of such FR exposure. The objectives of this research were (1) to determine spatial patterns of ≤ 48 polybrominated diphenyl ether (PBDE) congeners and ≤ 26 non-PBDE FRs, including organophosphate esters (OPEs), in nestling peregrine falcons (Falco peregrinus) across the Canadian Great Lakes-St. Lawrence River Basin (GL-SLR; 2010) and in the eastern Canadian Arctic (2007); (2) to identify temporal changes in FR concentrations from the mid-2000s to 2010 in GL-SLR peregrine nestlings; (3) to investigate the role of diet using stable isotopes on exposure patterns of quantifiable FRs; and (4) to assess possible associations between circulating FRs and total (T) thyroxine (TT₄) and triiodothyronine (TT₃), tocopherol, retinol and oxidative status (isoprostanes). The summed concentrations of the top 5 PBDEs (Σ₅) (BDE-47, -99, -100, -154, -153) were significantly higher in rural nestlings than urban nestlings in the GL-SLR, followed by the eastern Arctic nestlings. The PBDE congener profile of rural nestlings was dominated by BDE-99 (34‰), whereas BDE-209 (31‰) became dominant in the 2010 urban PBDE profile marking a shift since the mid-2000s. Low (ppb) concentrations of 25 novel non-PBDE FRs (e.g., 1,2-bis-(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenylethane (DBDPE)) were measured in the nestlings in at least one region, with the first report in peregrines of 15 novel non-PBDE FRs (e.g., 2-ethyl-1-hyxyl 2,3,4,5-tetrabromobenzoate (EHTBB), pentabromo allyl ether (PBPAE), tetrabromoethylcyclohexane (α-, β-DBE-DBCH)) as well as of tris (2-butoxyethyl) phosphate (TBOEP) (0-7.5ng/g ww) > tris(2-chloroisopropyl) phosphate (TCIPP) (0.1-5.5ng/g ww) > tris(2-chloroethyl) phosphate (TCEP) (0.02-2.0ng/g ww) > tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) (0-1.0ng/g ww). Within the GL-SLR, the urban nestlings' diet had significantly more terrestrial sources (greater δ¹³C values) than the broader, more aquatic-based diet of rural peregrines. Dietary source (δ¹³C) was significantly associated with concentrations of Σ₅PBDE, BDE-209, EHTBB, and 2,2-4,4',5,5'-hexabromobiphenyl (BB-153), with trophic level (δ¹⁵N) also positively associated with BDE-209 levels. Compared to urban nestlings, the rural nestlings had significantly lower circulating concentrations of thyroxine (TT₄), triiodothyronine (TT₃), a greater proportion of TT₃ relative to TT₄ (TT₃:TT₄), tocopherol and oxidative status (isoprostanes), but higher retinol levels; the most recalcitrant PBDE congener, BDE-153, in combination with low concentrations of some novel FRs, particularly octabromotrimethylphenyllindane (OBIND), may influence circulating thyroid hormones, especially TT₄, and retinol levels of peregrine falcon nestlings. These associations of FR-endocrine-biochemical measures suggest possible exposure-related changes in these birds and further study is warranted.

Emerging and legacy flame retardants in UK human milk and food suggest slow response to restrictions on use of PBDEs and HBCDD

The legacy flame retardants (LFRs) polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD), together with six emerging flame retardants (EFRs) were measured in United Kingdom (UK) human milk collected in 2010 (n=25) and 2014-15 (n=10). These data are the first report of the presence of EFRs in UK human milk. The most abundant EFR was β-tetrabromoethylcyclohexane (DBE-DBCH) (average=2.5ng/g lw; geometric mean=1.5ng/g lw), which is comparable to the concentrations of the most abundant LFRs i.e. BDE 47 and α-HBCDD at 2.8 and 2.1ng/g lw, respectively (geometric mean=2.1 and 1.7). The estimated median dietary intake of ΣEFRs by UK nursing infants was 18ng/kg bw/day. EFRs were also measured in UK foodstuffs with β-DBE-DBCH again the predominant compound detected, accounting - on average - for 64.5±23.4% of ΣEFRs. Average estimated dietary intakes of ∑EFRs in the UK were 89 and 26ng/day (1.3 and 2.6ng/body weight/day) for adults and toddlers, respectively. Concentrations of Σtri-hexa BDEs in our UK food samples exceeded those reported in UK samples from the same food categories collected in 2003-04 and 2006. Despite this and our recent report elsewhere of significant temporal declines in concentrations of BDE 209 in UK indoor dust (p<0.05) and HBCDDs in UK indoor dust and air (p<0.001), no significant temporal differences (p>0.05) were observed between concentrations of Σtri-hexa BDEs, BDE 209 and HBCDDs in human milk sampled in 2010 and those obtained in 2014-15. UK adult body burdens for EFRs were predicted via inhalation, diet and dust ingestion using a simple pharmacokinetic model. The predicted EFR body burdens compared well with observed concentrations in human milk.

Polybrominated diphenyl ethers (PBDEs) in US meat and poultry: 2012-13 levels, trends and estimated consumer exposures

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants whose use has contaminated foods and caused subsequent human exposures. To address the issue of possible human exposure, samples from a 2012-13 US meat and poultry (beef, pork, chicken, turkey) study were analysed for seven PBDEs. The mean summed concentrations of the seven BDE congeners (ΣPBDE) from beef, pork, chicken and turkey were 0.40, 0.36, 0.19, and 0.76 ng g^-1 lipid weight (lw). The range of ΣPBDEs for all meat classes was 0.01-15.78 ng g^-1 lw. A comparison of this study with a 2007-08 study revealed a decline in the median ΣPBDEs for all four meat classes, a reduction of 25.9% to 70.0%, with pork, chicken and turkey PBDE residues being statistically lower relative to the 2007-08 study. BDEs 47 and 99 contributed the most to the ΣPBDE concentrations, indicating likely animal exposures to the penta-BDE formulation. Based on the reported data an estimate of US consumer daily intake of PBDEs from meat and poultry was 6.42 ng day^-1.

PBDEs and Dechloranes in Raccoons in the Midwestern United States

Raccoons (Procyon lotor) are one of the most widespread and abundant mammals in North America. To evaluate the suitability of using raccoons as bioindicator species, we analyzed liver tissues (n = 32) collected from 2013 to 2015 for the presence of polybrominated diphenyl ethers (PBDEs) and Dechloranes. ∑PBDE concentrations ranged from 19.1 to 2125 ng/g lw (median = 98.0 ng/g lw) and did not differ between gender or age of raccoon. Dechloranes were detected in 38% of raccoons and ranged from 0.15 to 50.4 ng/g lw (median = 2.32 ng/g lw). The comparatively high PBDE concentrations, and presence of Dechloranes in the raccoons in our study suggest that biota in terrestrial habitats are still widely exposed to and susceptible to the bioaccumulation of current and emerging flame retardants.

Bioaccumulation and bound-residue formation of 14C-decabromodiphenyl ether in an earthworm-soil system

Decabromodiphenyl ether (DecaBDE) is one of the most frequently detected flame retardants in terrestrial environments. However, the fate of DecaBDE and its transport in an earthworm-soil system with and without a DecaBDE-degrading strain have rarely been evaluated. In this study, ¹⁴C-DecaBDE was self-synthesized, and a DBDE-degrading strain, Rhodococcus erythropolis, was used in an earthworm-soil system. DecaBDE showed limited degradation and mineralization after 35days of all treatments. The bound-residue (BR) formation in soil was <2.5% in the system containing earthworms, which was significantly higher (p<0.05) than that observed in the absence of earthworms (<0.45%). DecaBDE could be adsorbed by the earthworms with a BSAF of ≤0.31. The distribution of ¹⁴C-DecaBDE concentrations in the earthworm roughly followed the pattern of crop gizzard>digestive system>head>tail>body wall, suggesting that DecaBDE was mainly uptaken through ingestion. Up to 31% of the ¹⁴C-DecaBDE in the earthworms was not extractable, revealing that the total concentration of accumulated ¹⁴C-DecaBDE was underestimated. The results also showed that the presence of DecaBDE-degrading bacteria did not significantly affect the fate of DecaBDE and its accumulation in earthworms. The study indicates that the conventional assessment of the bioaccumulation and ecological effects of DecaBDE, which is based only on extractable concentrations, may underestimate the risks.

Relationships between polybrominated diphenyl ethers and transcription and activity of type 1 deiodinase in a gull highly exposed to flame retardants

Deca-brominated diphenyl ether (deca-BDE), composed mainly of BDE-209, is subject to usage restrictions in North America and Europe, although global action on its continued use has yet to be undertaken. Relatively large concentrations of polybrominated diphenyl ethers (PBDEs), especially BDE-209 and its higher brominated degradation products, have been reported in tissues of ring-billed gulls (Larus delawarensis) breeding near the densely populated city of Montreal (QC, Canada). There is limited knowledge of BDE-209 biotransformation and toxicokinetics in birds. Deiodinases, a class of enzymes catalyzing thyroid hormone conversion, have been suggested to be involved in BDE-209 debromination in birds. The objective of the present study was to investigate the relationships between PBDE concentrations and type 1 deiodinase (D1) transcription and in vitro activity (microsomes) in livers of Montreal-breeding ring-billed gulls. The ring-billed gulls exhibiting the highest D1 activity in liver microsomes accumulated the greatest liver concentrations of hepta-BDEs and octa-BDEs. Activity of D1 was inversely related to concentration ratios of BDE-209 to octa-BDEs and ∑hepta-BDE. An even stronger inverse relation was found between D1 activity and BDE-209 to ∑nona + octa + hepta-BDE concentration ratios. The messenger ribonucleic acid (mRNA) levels of D1 in gull livers were inversely associated with liver concentrations of ∑octa-BDE. The present study's findings suggest that D1 is potentially involved in BDE-209 biotransformation and accumulation of higher brominated PBDEs in livers of ring-billed gulls. Environ Toxicol Chem 2016;35:2215-2222. © 2016 SETAC.

In Vitro Metabolism of Photolytic Breakdown Products of Tetradecabromo-1,4-diphenoxybenzene Flame Retardant in Herring Gull and Rat Liver Microsomal Assays

Tetradecabromo-1,4-diphenoxybenzene (TeDB-DiPhOBz) is used as a flame retardant chemical and has been hypothesized to be the precursor of methoxylated polybrominated diphenoxybenzene (MeO-PB-DiPhOBz) contaminants reported in herring gulls from sites across the Laurentian Great Lakes. Here, by irradiating the parent TeDB-DiPhOBz (solution 1) with natural sunlight or UV, we prepared three solutions where solution 2 was dominated by the Br8-11-PB-DiPhOBzs, along with Br5-8-PB-DiPhOBzs (solution 3) and Br4-6-PB-DiPhOBzs (solution 4). The in vitro metabolism of TeDB-DiPhOBz and PB-DiPhOBzs was investigated using harvested wild herring gull (Larus argentatus) and adult male Wister-Han rat liver microsomal assays. After a 90 min incubation period of solution 1 in gull or rat microsomal assays, there was no significant (p > 0.05) depletion of TeDB-DiPhOBz. OH-PB-DiPhOBz metabolites were detectable after gull and rat microsomal assay incubation with solutions 3 or 4, and showed clear species-specific differences. Also detected were two polybrominated hydroxylated metabolites having polybenzofuran structures. Overall, this study suggested that TeDB-DiPhOBz is slowly metabolized in vitro, and also indicated that if wild herring gulls are exposed (e.g., via the diet) to photolytic products of TeDB-DiPhOBz, OH-PB-DiPhOBz and other metabolites could be formed. OH-PH-DiPhOBz are likely precursors to MeO-PB-DiPhOBz contaminants that we reported previously in eggs of wild Great Lakes herring gulls.

Hepatic ethoxyresorufin-O-deethylase induction in the common kingfisher from an electronic waste recycling site

The health effects of exposure to electronic waste (e-waste)-derived pollutants are an important issue. The authors explored the association between the hepatic levels of e-waste-derived halogenated contaminants (including polychlorinated biphenyls [PCBs], polybrominated diphenyl ethers [PBDEs], and polybrominated biphenyls [PBBs]) and hepatic ethoxyresorufin-O-deethylase (EROD) activity of the common kingfisher (Alcedo atthis) from an e-waste site and 2 reference sites in South China. The summed concentrations of PCBs, PBDEs, and PBBs ranged from 620 ng/g to 15 000 ng/g, 25 ng/g to 900 ng/g, and 14 ng/g to 49 ng/g wet weight, respectively, in the kingfishers from the e-waste site, and these values were significantly greater (2-3 orders of magnitude) than those obtained at the 2 reference sites. Correspondingly, significant hepatic EROD induction was observed in the kingfishers from the e-waste site compared with the reference sites. The EROD activity was significantly correlated to the levels of most of the PCB and PBDE congeners examined as well as PBB 153, suggesting that EROD induction may be evoked by these e-waste-derived pollutants. Environ Toxicol Chem 2016;35:1594-1599. © 2015 SETAC.

Influence of trophic ecology on the accumulation of dioxins and furans (PCDD/Fs), non-ortho polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in Mediterranean gulls (Larus michahellis and L. audouinii): A three-isotope approach

The impact of pollution caused by severe anthropogenic pressure in the Mediterranean Sea, an important biodiversity hotspot, requires continuous research efforts. Sources of highly toxic chemicals such as Persistent Organic Pollutants (POPs) are misunderstood in representative Mediterranean species, which limits our capability to establish proper conservation strategies. In the present study, eggs of Audouin's and yellow-legged gulls (Larus audouinii and L. michahellis) were used to investigate the trophic sources, as measured by δ(13)C, δ(15)N, and δ(34)S, of legacy POPs, in particular, polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and non-ortho polychlorinated biphenyls (no-PCBs), as well as recently-regulated POPs, e.g., polybrominated diphenyl ethers (PBDEs). Special attention was paid to the usefulness of rarely-explored δ(34)S ratios in explaining POP exposure in wildlife, and δ(34)S was the isotopic ratio that best explained POP variations among gulls in most cases, thus demonstrating its usefulness for understanding POP exposure in wildlife. Significant relationships between stable isotope signatures and POP concentrations revealed increasing levels of no-PCBs and low halogenated PCDD/Fs and PBDEs in Mediterranean gulls as the consumption of marine resources increases. In contrast, highly chlorinated and brominated congeners appeared to preferentially accumulate in gulls feeding primarily on refuse from dump sites and terrestrial food webs. The use of suitable dietary tracers in the study of POPs in yellow-legged gulls revealed the importance of dump sites as a source of POPs in Mediterranean seabirds, which has not previously been reported. In contrast, the preferential accumulation through marine food webs of low chlorinated PCCD/Fs and no-PCBs, which show the highest toxic equivalents factors (TEFs), led to a significantly greater toxicological concern in Audouin's as compared to yellow-legged gulls. Audouin's gull exposure to POPs appears primarily related to the pelagic food webs commonly exploited by fisheries, highlighting the need for further research given the potential impact on human consumption.

Facilitated Leaching of Additive-Derived PBDEs from Plastic by Seabirds' Stomach Oil and Accumulation in Tissues

Our previous study suggested the transfer of polybrominated diphenyl ether (PBDE) flame retardants from ingested plastics to seabirds' tissues. To understand how the PBDEs are transferred, we studied leaching from plastics into digestive fluids. We hypothesized that stomach oil, which is present in the digestive tract of birds in the order Procellariiformes, acts as an organic solvent, facilitating the leaching of hydrophobic chemicals. Pieces of plastic compounded with deca-BDE were soaked in several leaching solutions. Trace amounts were leached into distilled water, seawater, and acidic pepsin solution. In contrast, over 20 times as much material was leached into stomach oil, and over 50 times as much into fish oil (a major component of stomach oil). Analysis of abdominal adipose, liver tissue, and ingested plastics from 18 wild seabirds collected from the North Pacific Ocean showed the occurrence of deca-BDE or hexa-BDEs in both the tissues and the ingested plastics in three of the birds, suggesting transfer from the plastic to the tissues. In birds with BDE209 in their tissues, the dominance of BDE207 over other nona-BDE isomers suggested biological debromination at the meta position. Model calculation of PBDE exposure to birds based on the results of the leaching experiments combined with field observations suggested the dominance of plastic-mediated internal exposure to BDE209 over exposure via prey.

Spatial and temporal comparisons of legacy and emerging flame retardants in herring gull eggs from colonies spanning the Laurentian Great Lakes of Canada and United States

In the Laurentian Great Lakes basin of North America, an increasing number of chemicals of emerging concern (CECs) are being investigated, including legacy and replacement flame retardants (FRs). In the present study, 14 polybrominated diphenyl ethers (PBDEs), 23 non-PBDEs halogenated FRs (NPHFRs) and 16 organophosphate ester FRs (OPE-FRs) were analyzed in 100 individual eggs collected in 2012 and 2013 and in 15 egg pools of herring gulls collected in 2012 from 20 colonies across the entire Laurentian Great Lakes basin. For CEC-FRs in eggs from all colonies, 14 PBDEs, 12 NPHFRs and 9 OPE-FRs were quantifiable in at least one of the 115 analyzed samples. The mean sum PBDE (Σ14PBDE) concentrations ranged from 244 to 657 ng/g wet weight (ww), and on average were 1-2 orders of magnitude greater than the Σ12NPHFR concentrations (13.8-35.6 ng/g ww), and 2-3 orders of magnitude greater than Σ9OPE-FR concentrations (0.31-2.14 ng/g ww). Mean Σ14PBDE and sum of syn- and anti-Dechlorane Plus isomer (Σ2DDC-CO) concentrations in eggs from colonies within Laurentian Great Lakes Areas of Concern (AOCs) were in most cases greater than in eggs from nearby colonies outside of AOCs. Comparing CEC-FR concentrations in eggs collected in 2012-2013 to those previously measured in eggs collected approximately 7 years earlier (2006 and 2008) showed that Σ7PBDE (BDE-28, -47, -100, -99, -154,-153 and -183) mean concentrations in eggs from 6 colonies were approximately 30% less than they were in eggs from the same colonies from the earlier time period, whereas 3 current-use FR (BDE-209, HBCDD and Σ2DDC-CO) concentrations were significantly greater (p<0.05) than previously measured. Between 2006 and 2013 there were significant changes in individual PBDE patterns for BDE-71, -138, -153, -203, -206 and -207. Among all of the examined CEC-FRs, concentrations of Σ4PBDE (BDE-47, -99, -100 and -153) and HBCDD in gull eggs from all colonies were greater than or comparable to their lowest observed effect concentrations (LOECs) based on in ovo egg injection studies. Overall, the current profiles of a broad suite of FRs in Laurentian Great Lakes herring gull eggs highlights the need to better understand e.g., exposure-effect implications and metabolism of FRs, i.e. OPE-FRs, and emphasizes the importance of continued monitoring of CEC-FRs whose concentrations appear to be increasing, including BDE-209, HBCDD and DDC-COs.

Trends of polybrominated diphenyl ethers and hexabromocyclododecane in eggs of Canadian Arctic seabirds reflect changing use patterns

Due to the substantial use and release of polybrominated diphenyl ether (PBDE) flame retardants in North America, PBDE concentrations in North American marine biota are among the highest in the world. In this study, we compared PBDE concentrations and congener patterns in eggs of five seabird species (thick-billed murres, northern fulmars, black guillemots, glaucous gulls, black-legged kittiwakes) breeding at a colony in the Canadian Arctic in 1993, 2008 and 2013. Temporal trends of PBDEs (1975-2014) and another flame retardant, hexabromocyclododecane (HBCD) (2003-2014), were also examined in eggs of two seabird species, the thick-billed murre and northern fulmar. BDE-47 generally dominated the BDE congener profiles in eggs of all five species. Glaucous gulls had the highest concentrations of both ΣPBDE and BDE-47, and northern fulmars, the lowest. ΣPBDE concentrations increased exponentially in eggs of both thick-billed murres and northern fulmars from 1975 to 2003 with doubling times of 9.1 years in the murres and 7.2 years in the fulmars. From 2003 to 2008/09, ΣPBDE decreased rapidly in the murres and fulmars to concentrations not significantly different from those recorded in 1975 and 1987 for each species. After 2008/09, ΣPBDE concentrations plateaued. BDE-47 followed a similar temporal trend to that of ΣPBDE concentrations. These concentration trends were consistent with the phase-out of the penta- and octa-BDE products from the North American market in the mid-2000s. There was an overall decline in concentrations of HBCD in murre eggs from 2003 to 2014, whereas concentrations in the fulmar eggs increased from 2003 to 2006 followed by a decline to 2014. The ratio of HBCD to BDE-47 suggests that northern fulmars showed more of a European contaminant signature, and thick-billed murres, more of a North American signature.

Contaminants of legacy and emerging concern in terrestrial passerines from a nature reserve in South China: Residue levels and inter-species differences in the accumulation

Knowledge is limited about the bioaccumulation of persistent halogenated compounds (PHCs) in terrestrial wildlife. Several PHCs, including dichlorodiphenyltrichloroethane (DDT) and its metabolites (designated as DDTs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenylethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and stable isotopes (δ(15)N and δ(13)C) were analyzed in the muscle of four terrestrial passerines, Parus major, Copsychus saularis, Pycnonotus sinensis and Pycnonotus jocosus, from a nature reserve in South China. P. major had the highest PHC concentrations, with median values of 1060, 401, 92, 25 and 0.3 ng/g lipid weight for DDTs, PCBs, PBDEs, DBDPE and BTBPE, respectively. Fractions of DDT in P. jocosus and PCBs 153, 118 and 180 in C. saularis were higher compared with the other species. The inter-species differences in PHC concentrations and profiles could be attributed to the differences in trophic level, diet, living habits and metabolic capacity among the birds.

Investigating endocrine and physiological parameters of captive American kestrels exposed by diet to selected organophosphate flame retardants

Organophosphate triesters are high production volume additive flame retardants (OPFRs) and plasticizers. Shown to accumulate in abiotic and biotic environmental compartments, little is known about the risks they pose. Captive adult male American kestrels (Falco sparverius) were fed the same dose (22 ng OPFR/g kestrel/d) daily (21 d) of tris(2-butoxyethyl) phosphate (TBOEP), tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), or tris(1,2-dichloro-2-propyl) phosphate (TDCIPP). Concentrations were undetected in tissues (renal, hepatic), suggesting rapid metabolism. There were no changes in glutathione status, indicators of hepatic oxidative status, or the cholinergic system (i.e., cerebrum, plasma cholinesterases; cerebrum muscarinic, nicotinic receptors). Modest changes occurred in hepatocyte integrity and function (clinical chemistry). Significant effects on plasma free triiodothyronine (FT3) concentrations occurred with exposure to TBOEP, TCEP, TCIPP, and TDCIPP; TBOEP and TCEP had additional overall effects on free thyroxine (FT4), whereas TDCIPP also influenced total thyroxine (TT4). Relative increases (32%-96%) in circulating FT3, TT3, FT4, and/or TT4 were variable with each OPFR at 7 d exposure, but limited thereafter, which was likely maintained through decreased thyroid gland activity and increased hepatic deiodinase activity. The observed physiological and endocrine effects occurred at environmentally relevant concentrations and suggest parent OPFRs or metabolites may have been present despite rapid degradation.

Uptake, distribution, depletion, and in ovo transfer of isomers of hexabromocyclododecane flame retardant in diet-exposed American kestrels (Falco sparverius)

Hexabromocyclododecane (HBCDD) is a flame retardant and a global contaminant, yet the toxicokinetics of HBCDD diastereoisomers remains unknown in wildlife species. The present study examined in captive American kestrels (Falco sparverius) (diastereo) isomer-specific HBCDD uptake, depletion, tissue distribution, and transfer to eggs in a dietary dosing study with an HBCDD technical mixture (HBCDD-TM). Adult tissue and plasma collections were from separate cohorts of unpaired individual males (n = 10) and females (n = 10) exposed for 21 d to 800 ng/g wet weight of HBCDD-TM (in safflower oil and injected into their cockerel [brain] diet), followed by a 25-d depuration period. A separate cohort of 12 males only was used for control adult tissue and plasma collections. For egg collections, separate cohorts of 11 control pairs (n = 22 birds) and 20 HBCDD-exposed pairs (n = 40 birds) were allowed to breed, and their eggs were collected (n = 19 exposed eggs and n = 10 control eggs). The sum (Σ) HBCDD concentrations were near or below detection (<0.01-0.1 ng/g wet wt) in all control samples but quantifiable in all samples from exposed birds (no differences [p > 0.05] between males and females). Arithmetic mean ΣHBCDD concentrations were highest in fat >> eggs > liver > plasma. The mean ΣHBCDD depletion rate in plasma between the uptake and depuration periods was estimated to be 0.22 ng/g/d with a half-life of approximately 15 d. The γ-HBCDD diastereoisomer was >60% of the ΣHBCDD in plasma after the uptake period and similar to the HBCDD-TM (∼80%). After the depuration period, α-HBCDD was >70% of the HBCDD in plasma, fat, liver, and eggs; and this α-HBCDD domination indicated isomer-specific accumulation as a result of selective metabolism, uptake, protein binding, and/or in ovo transport.

Methodology and determination of tetradecabromo-1, 4-diphenoxybenzene flame retardant and breakdown by-products in sediments from the Laurentian Great Lakes

Tetradecabromo-1,4-diphenoxybenzene (TeDB-DiPhOBz) is a brominated polyphenyl ether flame retardant (FR) that is known to photolytically degrade to produce lower brominated polybrominated-diphenoxybenzenes (PB-DiPhOBzs), which may be precursors to MeO-PB-DiPhOBzs recently reported in the Great Lakes herring gulls eggs. To our knowledge, there are no reports on TeDB-DiPhOBz or other PB-DiPhOBz by-products in any environmental sample. The present study analyzed for the presence of PB-DiPhOBzs (including TeDB-DiPhOBz) and MeO-PB-DiPhOBzs in surficial sediment from sites in Saginaw Bay in western Lake Huron (n = 7), and in comparison to southern Lake Huron (open water) (n = 5) and Lake Erie (n = 3) sediment collected in the summers of 2012 or 2013. To analyze for possible PB-DiPhOBzs (Br14–Br0), the first known analytical method was developed for extraction and cleanup of sediment samples, and analysis by HPLC–atmospheric pressure photoionization (−)-quadrupole time-of-flight-mass spectrometry. The overall recovery efficiency was optimized to on average 33–104% progressing from Br14- to Br10-PB-DiPhOBzs. Br10- to Br14-PB-DiPhOBz detection and quantification limits ranged from 0.05 to 0.15 ng g(−1) dw and 0.17 to 0.49 ng g(−1) dw, respectively. Although this is the first report, PB-DiPhOBzs (Br14–Br10) and MeO-PB-DiPhOBzs were not detectable in any sediment sample. This included a site near the mouth of the highly FR-contaminated Saginaw River, near the confined disposal facility (CDF) located in Saginaw Bay at Channel-Shelter Island, which receives dredged sediment from the Saginaw River. Our findings suggest sediments from the presently studied sites in the Great Lakes ecosystem are not a sink for TeDB-DiPhOBz and PB-DiPhOBz by-product contaminants.

Photolytic degradation products of two highly brominated flame retardants cause cytotoxicity and mRNA expression alterations in chicken embryonic hepatocytes

Tetradecabromo-1,4-diphenoxybenzene (TeDB-DiPhOBz) and 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether (BDE-209) are photolytically unstable flame retarding chemicals. Here, photocatalyzed byproducts of TeDB-DiPhOBz and BDE-209 (i.e Br(8)- to Br(11)-PB-DiPhOBz congeners from TeDB-DiPhOBz, and Br(6)- to Br(8)-BDE congeners from BDE-209), formed after 21 days of natural sunlight irradiation (SI), were assessed for exposure effects on cytotoxicity and mRNA expression levels of selected genes in chicken embryonic hepatocytes (CEH). CEHs were exposed for 36 h to concentrations of SI- and nonirradiated (NI)-TeDB-DiPhOBz and BDE-209. Cytotoxic effects were observed only in CEH exposed to 50 μM SI-BDE-209. Results from a custom-designed Avian ToxChip polymerase chain reaction array showed that NI-TeDB-DiPhOBz and NI-BDE-209, up to maximum concentrations of 1.9 and 9 μM, respectively, caused limited changes in mRNA levels of 27 genes from toxicologically relevant pathways, including phase I/II metabolism, the thyroid hormone pathway, lipid/cholesterol metabolism, oxidative stress, immune response, and cell death. In contrast, 12 and 14 of the 27 genes were altered after exposure to 25 μM SI-TeDB-DiPhOBz or 10 μM SI-BDE-209, respectively. Aryl hydrocarbon receptor (AhR)-related CYP1A4 mRNA levels were the most altered on the PCR array with an induction of 560- and 5200-fold after exposure to 1 or 25 μM SI-TeDB-DiPhOBz, respectively, and 2500- and 2300-fold after exposure to 1 or 10 μM SI-BDE-209, respectively. A dioxin-responsive luciferase reporter gene assay confirmed that the CYP1A4 inductions were independent of the dissolution solvents used (tetrahydrofuran/n-hexane, n-hexane, or methanol) during photolysis. Overall, degradation of TeDB-DiPhOBz and BDE-209 by natural sunlight generates byproducts that affect in vitro expression of genes, especially the AhR-mediated CYP1A4.

Assessment of concentrations and effects of organohalogen contaminants in a terrestrial passerine, the European starling

European starlings (Sturnus vulgaris) are a valuable model species for the assessment of concentrations and effects of environmental contaminants in terrestrial birds. Polybrominated diphenyl ethers (PBDEs) are found in birds throughout the world, but relatively little is known of their concentrations or effects in free-living terrestrial passerines. We used a nest box population of European starlings to 1) measure the variation in egg concentrations of persistent organohalogen contaminants at an agricultural site, and 2) assess whether individual variation in PBDE concentrations in eggs was related to reproductive parameters, as well as maternal or nestling characteristics including body condition, thyroid hormones, oxidative stress, and hematocrit. As PBDEs were the main contaminant class of interest, we only assessed a subset of eggs for other organohalogen contaminants to establish background concentrations. Exposure to organohalogen contaminants was extremely variable over this relatively small study area. Geometric mean wet weight concentrations (range in brackets) of the major contaminants were 36.5 (12-174) ng/g ΣDDT (n=6 eggs) and 10.9 (2-307) ng/g ΣPBDEs (n=14). ΣPCBs at 3.58 (1.5-6.4) ng/g (n=6) were lower and less variable. There were low levels of other organochlorine (OC) pesticides such as dieldrin (2.02 ng/g), chlordanes (1.11 ng/g) and chlorobenzenes (0.23 ng/g). The only form of DDT detected was p,p'-DDE. The congener profiles of PBDEs and PCBs reflect those of industrial mixtures (i.e. DE-71, Aroclors 1254, 1260 and 1262). For all of the contaminant classes, concentrations detected in eggs at our study site were below levels previously reported to cause effects. Due to small sample sizes, we did not assess the relationship between ΣPCBs or ΣOCs and adult or chick condition. We observed no correlative relationships between individual variation in PBDE concentrations in starling eggs and reproductive success, maternal condition, or nestling condition in the corresponding nests.