Triclosan is the Predominant Antibacterial Compound in Ontario Sewage Sludge.

Sewage treatment plants (STPs) accumulate both antibiotic and nonantibiotic antimicrobial compounds that can select for antibiotic resistant bacteria. Herein, we aimed to identify the predominant antibacterial compounds impacting E. coli from Ontario sewage sludge consisting of thousands of unknown compounds. Among the 10 extracted sludge samples, 6 extracts exerted significant growth inhibition effects in E. coli. A total of 103 compounds were tentatively detected across the 10 sludge samples by suspect screening, among which the bacterial enoyl-ACP reductase (FabI) inhibitor triclocarban was detected at the highest abundance. A hypomorphic FabI knockdown E. coli strain was highly susceptible to the sludge extracts, confirming FabI inhibitors as the primary antibacterial compounds in the sludge. Protein affinity pulldown identified triclosan as the major ligand binding to a His-tagged FabI protein from the sludge, despite the higher abundance of triclocarban in the same samples. Effect-directed analysis was used to determine the contributions of triclosan to the observed antibacterial potencies. Antibacterial effects were only detected in F17 and F18 across 20 fractions, which was consistent with the elution of triclosan and triclocarban in the same two fractions. Further, potency mass balance analysis confirmed that triclosan explained the majority (58-113%) of inhibition effects from sludge extracts. This study highlighted triclosan as the predominant antibacterial compound in sewage sludge impacting E. coli despite the co-occurrence of numerous other antibiotics and nonantibiotics.

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.

Disruption by stealth - Interference of endocrine disrupting chemicals on hormonal crosstalk with thyroid axis function in humans and other animals.

Thyroid hormones (THs) are important regulators of growth, development, and homeostasis of all vertebrates. There are many environmental contaminants that are known to disrupt TH action, yet their mechanisms are only partially understood. While the effects of Endocrine Disrupting Chemicals (EDCs) are mostly studied as "hormone system silos", the present critical review highlights the complexity of EDCs interfering with TH function through their interactions with other hormonal axes involved in reproduction, stress, and energy metabolism. The impact of EDCs on components that are shared between hormone signaling pathways or intersect between pathways can thus extend beyond the molecular ramifications to cellular, physiological, behavioral, and whole-body consequences for exposed organisms. The comparatively more extensive studies conducted in mammalian models provides encouraging support for expanded investigation and highlight the paucity of data generated in other non-mammalian vertebrate classes. As greater genomics-based resources become available across vertebrate classes, better identification and delineation of EDC effects, modes of action, and identification of effective biomarkers suitable for HPT disruption is possible. EDC-derived effects are likely to cascade into a plurality of physiological effects far more complex than the few variables tested within any research studies. The field should move towards understanding a system of hormonal systems' interactions rather than maintaining hormone system silos.

Suspect and Nontarget Screening Revealed Class-Specific Temporal Trends (2000-2017) of Poly- and Perfluoroalkyl Substances in St. Lawrence Beluga Whales.

The global use of >3000 per- and polyfluoroalkyl substances (PFASs) has given rise to chemical regulatory action. However, limited information exists regarding current and historical emissions for the majority of PFASs under currently implemented regulations. This study employed suspect and nontarget screening to examine the temporal trends of legacy and unregulated PFASs in liver of the endangered beluga whale (Delphinapterus leucas) population from the St. Lawrence Estuary in Canada collected from 2000 to 2017. A suite of 54 PFASs were tentatively identified, and were grouped into nine structurally distinct classes. Single-hydrogenated perfluoro carboxylic acids (H-PFCAs), single-hydrogenated sulfonamides (H-Sulfonamides), as well as other select sulfonamides were detected for the first time in wildlife. Greater concentrations of the majority of PFASs were determined in newborns and juveniles than in adults, suggesting effective placental and lactational transfer of PFASs. Legacy per- and polyfluoroalkyl acids and perfluorooctane sulfonamide in beluga whale liver were found to significantly decrease in concentration between 2000 and 2017, while unregulated short-chain PFAS alternatives, H-PFCAs, and odd-chain FTCAs were found to increase over time. The implementation of suspect and nontarget screening revealed class-specific temporal trends of PFASs in SLE beluga whales, and supported continuous emissions of unregulated PFASs into the environment.

Lipid metabolites as indicators of body condition in highly contaminant-exposed belugas from the endangered St. Lawrence Estuary population (Canada).

The endangered St. Lawrence Estuary (SLE) beluga population is declining and has shown no sign of recovery over the past decades despite several protective measures. Changes in the availability of food resources and exposure to organohalogen contaminants have been suggested as potential factors limiting the recovery of this population. Studies on SLE belugas have suggested that contaminant exposure may perturb energy metabolism, however, whether this translates into changes in energy reserves (lipid composition) and body condition is unknown. The objective of this study was to investigate the relationships between body condition and concentrations of organohalogens (polychlorinated biphenyls, organochlorine pesticides, and flame retardants) and a range of lipid metabolites (fatty acids, acylcarnitines, lysophosphatidylcholines, phosphatidylcholines, and sphingomyelins) in blubber samples collected from 51 SLE beluga carcasses recovered between 1998 and 2016 for which the cause of mortality was documented. Blubber Σ9fatty acid concentrations in SLE belugas significantly decreased between 1998 and 2016, suggesting a decline in energy reserves over the past two decades. Concentrations of several phosphatidylcholine analogues were greater in blubber of beluga males and/or females that were in poor body condition compared to those in good body condition. Moreover, concentrations of phosphatidylcholine acyl-alkyl C32:2 were greater in females that died from primary starvation (poor body condition). Greater concentrations of Σ12emerging flame retardants were also found in blubber of SLE beluga females that were in poorer body condition. This study suggests that the use of membrane lipids including phosphatidylcholine concentrations may be a good indicator of body condition and energy reserve status in blubber of marine mammals.

Time-dependent biological responses of juvenile yellow perch (Perca flavescens) exposed in situ to a major urban effluent.

Municipal wastewater treatment plant (WWTP) effluents are significant sources of organic and inorganic pollutants to aquatic ecosystems. Several studies have shown that the health of aquatic organisms can be adversely impacted following exposure to these complex chemical mixtures. The objective of this study was to examine the effects of in situ exposure in the St. Lawrence River (QC, Canada) of juvenile yellow perch (Perca flavescens) to a major WWTP effluent. Perch were caged at a reference site in the St. Lawrence River and downstream of a WWTP effluent-influenced site for one, three, and six weeks. Fish kept in controlled laboratory setting were also examined at the beginning of the experiment to evaluate the potential effect of caging on fish. Liver metabolites and gill oxidative stress biomarkers as well as body condition of perch were investigated at four time points (zero, one, three, and six weeks). Nitrogen (δ15N) and carbon (δ13C) stable isotopes as well as tissue concentrations of halogenated flame retardants and trace metals were also analyzed. Results indicated that body condition of perch caged in the effluent increased after three and six weeks of exposure compared to that of reference fish. Perch caged at the WWTP effluent-influenced site also had higher muscle δ13C and slightly depleted muscle δ15N after three and six weeks of exposure, suggesting differences in sewage-derived nutrient assimilation between sites. Concentrations of Σ34 polybrominated diphenyl ether (PBDE) were 2-fold greater in perch exposed downstream of the WWTP compared to those caged at the reference site. Metal concentrations in kidney of perch after three weeks of exposure were significantly lower at the effluent-influenced site. Kidney concentrations of Cd, Cu, Se, As, Zn and Fe were, however, higher after six weeks of exposure, supporting that metal accumulation is time- and element-specific. The metabolomes of perch from the effluent-influenced and reference sites were similar, but were distinct from the laboratory control fish, suggesting a caging effect on fish. Seven liver metabolites (glucose, malate, fumarate, glutamate, creatinine, histamine, and oxypurinol) were significantly more abundant in perch from cages than in the laboratory control perch. The combination of metabolomics and physiological variables provides a powerful tool to improve our understanding of the mechanisms of action of complex environmental pollutant mixtures in wild fish.

Habitat use strategy influences the tissue signature of trace elements including rare earth elements in an urban-adapted omnivorous bird.

Concentrations of trace elements vary naturally between geological environments and as a result of emissions from anthropogenic activities. Habitat use strategy is an important determinant of trace element concentrations in tissues and eggs of wild birds. However, a scarcity of studies have documented the relationships between individual bird movements related to foraging activities and exposure to contaminants including trace elements. The objective of the present study was to investigate the influence of habitat use strategy, determined using GPS-based telemetry, on the liver concentrations of selected trace elements including rare earth elements (REEs) as well as lead (Pb) isotope ratios in an urban-adapted omnivorous bird, the ring-billed gull (Larus delawarensis). Male (n = 20) and female (n = 18) ring-billed gulls breeding near Montreal (QC, Canada) in one of the largest colony in North America were tracked using miniature GPS devices to characterize their movements over a 10-days period. The time spent foraging by both male and female gulls in landfills and wastewater basins positively correlated with liver Pb concentrations. A positive correlation was also found between the time spent foraging in agricultural fields and liver concentrations of yttrium (Y) in male and female ring-billed gulls. Heavy REE concentrations were significantly greater in female gull liver relative to those of males, although this was not associated with the time spent in any foraging habitats. Pb isotope ratios (208Pb/206Pb and 206Pb/207Pb) in the liver of male ring-billed gulls tended to be lower in individuals that foraged in landfills, thus indicating that they may have been exposed to different Pb sources relative to birds that visited other sites. This study provided valuable information on the potential sources of trace elements at the landscape level in free-ranging birds spanning urbanized environments.

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.

Temporal trends of PBDEs and emerging flame retardants in belugas from the St. Lawrence Estuary (Canada) and comparisons with minke whales and Canadian Arctic belugas.

An exponential level increase of the ubiquitous halogenated flame retardant (HFR) class polybrominated diphenyl ether (PBDE) has been documented during the 1990s in endangered belugas (Delphinapterus leucas) from the St. Lawrence Estuary (SLE), Eastern Canada. The recent worldwide bans and regulations of PBDE mixtures led to their replacement by alternative HFRs (so-called emerging HFRs) that are increasingly being reported in various environmental compartments. There are, however, limited knowledge on the spatial and temporal trends of PBDEs and emerging HFRs in cetaceans, especially after restrictions on PBDE usage. The first objective of this study was to investigate the occurrence of HFRs (35 PBDE congeners and 13 emerging compounds) in the blubber of belugas and minke whales (Balænoptera acutorostrata) found dead in the Estuary or Gulf of St. Lawrence as well as belugas from Nunavik (Canadian Arctic) collected as part of the Inuit subsistence hunt. A second objective was to investigate the trends of HFR concentrations in SLE beluga males between 1997 and 2013. PBDEs were the most abundant HFRs in all three whale populations, while hexabromobenzene (HBB), Chlordene Plus (CPlus), Dechlorane Plus (DP), and Dechlorane 604 Component B (Dec-604 CB) were quantified in the majority of blubber samples. Overall, concentrations of emerging HFRs were notably greater in SLE belugas compared to the two other whale populations, with the exception of DP and Dec-604 CB that were found in greater concentrations in Canadian Arctic belugas. No significant trend in blubber PBDE concentrations was found in SLE belugas during this 17-year period. This suggests that global PBDE regulations are too recent to observe changes in PBDE concentrations in belugas from this highly HFR-exposed environment. In contrast, concentrations of HBB and CPlus in SLE belugas decreased slightly from 1997 to 2013, while DP increased up until 2000 and decreased slightly thereafter. The occurrence and temporal variations of PBDEs and their replacement products in these cetaceans warrant continuous monitoring.

Feather corticosterone during non-breeding correlates with multiple measures of physiology during subsequent breeding in a migratory seabird.

Carry-over effects in migratory birds are likely mediated by physiological processes that are activated in response to environmental variation. Such processes affect body condition and/or reproductive success, and can include corticosterone (CORT) because this hormone responds to environmental stressors and influences energy balance. Few studies have considered how CORT levels during non-breeding relate to a broader physiological profile during subsequent breeding, and fewer still have considered measures other than body condition. To explore CORT's potential role in carry-over effects, we investigated the relationship between CORT and foraging ecology of northern gannets (Morus bassanus) during the non-breeding period, and tested for associations between these factors and variation in a suite of physiological and biochemical metrics during subsequent breeding. Northern gannets are the largest seabird top predator in the North Atlantic and were among the hardest hit by the Deepwater Horizon oil blowout in the Gulf of Mexico in 2010. We used light-level geolocators to confirm winter origins of individuals in our study. No interrelationships were found among levels of CORT from feathers grown during non-breeding (CORTf) and variation in foraging ecology, measured by stable isotopes of carbon (δ13C) and nitrogen (δ15N) from the same feathers. CORTf was correlated negatively with hematocrit and positively with triglyceride measured during subsequent incubation, and explained more variation in these variables than did body mass during incubation. These findings provide support for the hypothesis that energy management, measured using CORTf, during non-breeding carries over to influence physiological measures other than body condition. Gannets that previously wintered within the Gulf of Mexico in the years following the Deepwater Horizon oil blowout had higher levels of CORTf compared to birds that wintered along the Atlantic coast, suggesting an increased energetic cost associated with visiting the Gulf of Mexico. Our results indicate that CORT during non-breeding is associated with a broader physiological profile during subsequent breeding than previously reported in birds.

Short-term fasts increase levels of halogenated flame retardants in tissues of a wild incubating bird.

Many species are adapted for fasting during parts of their life cycle. For species undergoing extreme fasts, lipid stores are mobilized and accumulated contaminants can be released to exert toxicological effects. However, it is unknown if short-term fasting events may have a similar effect. The objective of this study was to determine if short successive fasts are related to contaminant levels in liver and plasma of birds. In ring-billed gulls (Larus delawarensis), both members of the pair alternate between incubating the nest for several hours (during which they fast) and foraging, making them a useful model for examining this question. Birds were equipped with miniature data loggers recording time and GPS position for two days to determine the proportion and duration of time birds spent in these two activities. Liver and plasma samples were collected, and halogenated flame retardants (HFRs) (PBDEs and dechlorane plus) and organochlorines (OCs) (PCBs, DDTs, and chlordane-related compounds) were determined. Most birds (79%) exhibited plasma lipid content below 1%, indicating a likely fasted state, and plasma lipid percent declined with the number of hours spent at the nest site. The more time birds spent at their nest site, the higher were their plasma and liver concentrations of HFRs. However, body condition indices were unrelated to either the amount of time birds fasted at the nest site or contaminant levels, suggesting that lipid mobilization might not have been severe enough to affect overall body condition of birds and to explain the relationship between fasting and HFR concentrations. A similar relationship between fasting and OC levels was not observed, suggesting that different factors are affecting short-term temporal variations in concentrations of these two classes of contaminants. This study demonstrates that short fasts can be related to increased internal contaminant exposure in birds and that this may be a confounding factor in research and monitoring involving tissue concentrations of HFRs in wild birds.

Tracking the sources of polybrominated diphenyl ethers in birds: foraging in waste management facilities results in higher DecaBDE exposure in males.

Differences in feeding ecology are now recognized as major determinants of inter-individual variations in contaminant profiles of free-ranging animals, but exceedingly little attention has been devoted to the role of habitat use. Marked inter-individual variations and high levels of polybrominated diphenyl ethers (PBDEs) (e.g., DecaBDE) have previously been documented in ring-billed gulls (Larus delawarensis) breeding in a colony near Montreal (QC, Canada). However, the environmental sources of these compounds, and thus the reasons causing these large inter-individual variations remain unidentified. In the present study, we used GPS-based telemetry (±5 to 10m precision) to track ring-billed gulls from this colony to reconstruct their movements at the landscape level. We related habitat use of individual gulls (n=76) to plasma concentrations (ng/g ww) and relative contributions (percentages) to Σ38PBDEs of major congeners in the internationally restricted PentaBDE and current-use DecaBDE mixtures. Male gulls that visited waste management facilities (WMFs; i.e., landfills, wastewater treatment plants and related facilities; 25% of all GPS-tracked males) exhibited greater DecaBDE (concentrations and percentages) and lower PentaBDE (percentages) relative to those that did not. In contrast, no such relationships were found in females. Moreover, in males, DecaBDE (concentrations and percentages) increased with percentages of time spent in WMFs (i.e., ~5% of total foraging time), while PentaBDE (percentages) decreased. No relationships between percentages of time spent in other habitats (i.e., urban areas, agriculture fields, and St. Lawrence River) were found in either sex. These findings suggest that animals breeding in the vicinity of WMFs as well as mobile species that only use these sites for short stopovers to forage, could be at risk of enhanced DecaBDE exposure.

Nutritional stress in Northern gannets during an unprecedented low reproductive success year: can extreme sea surface temperature event and dietary change be the cause?

Reproductive success of seabirds is tightly associated with availability of their prey for which the spatiotemporal distribution may be influenced by sea surface temperature (SST) fluctuations. The objective of this study was to investigate whether Northern gannets (Morus bassanus) from the largest colony in North America (Bonaventure Island, Quebec, Canada) were in negative nutritional state during the unprecedented low reproductive success year of 2012, and whether this was associated with changes in SST anomalies and diet. The incubation period of gannets in 2012 was characterized by a significant decline, from early to late incubation, in plasma triglyceride levels that was associated with an increase in plasma corticosterone levels. However, no changes in plasma glycerol and ß-hydroxybutyrate levels were noted. SST anomalies recorded in this area (south of the Gulf of St. Lawrence) during the breeding period were consistently higher in 2012 compared to the previous year (a better reproductive success year). Based on signatures of stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes in gannet red blood cells and in whole fish homogenates of three major preys (mackerel, herring, and capelin), a minor dietary shift was noted between those years and incubation periods. In light of these findings, it is suggested that the extreme warm-water perturbation event that prevailed in the Gulf of St. Lawrence during summer 2012 was associated with a rapid deterioration of nutritional condition of Bonaventure Island gannets during the incubation. These suboptimal physiological changes likely contributed to the dramatic decline in reproductive success reported in this colony.

Variations in thyroid hormone levels in endangered St. Lawrence Estuary belugas: Potential linkage with stress and organohalogen contaminant exposure.

The St. Lawrence Estuary (SLE) beluga (Delphinapterus leucas) population is highly exposed to an array of contaminants that were identified as one of the causes to the non-recovery of this endangered and declining population. In the last decade, an increasing number of parturition-associated complications and calf mortality has been reported in this population. It was suggested that elevated exposure to organohalogens (e.g., the halogenated flame retardants polybrominated diphenyl ethers [PBDEs]) and stress could play a role in this phenomenon by perturbing thyroid hormones. The objective of this study was to investigate the impact of concentrations of organohalogen contaminants and stress (cortisol levels) on thyroid hormone variations in adult male and female SLE belugas. Because plasma could not be collected in SLE belugas for ethical reasons, skin biopsy (n = 40) was used as a less-invasive alternative matrix to determine organohalogens (PBDEs and other halogenated flame retardants, polychlorinated biphenyls, and organochlorine pesticides), cortisol, and thyroid hormones (triiodothyronine [T3] and thyroxine [T4]), and their metabolites reverse T3 and 3,5-diiodothyronine [3,5-T2]). Cortisol and thyroid hormones were analyzed by ultra-performance liquid chromatography-multiple reactions monitoring mass spectrometry (UPLC-MRM/MS). This method was compared using skin and plasma samples obtained from Arctic belugas. Comparisons of linear models showed that cortisol was a weak predictor for T4, rT3 and 3,5-T2. Specifically, there was a weak significant negative association between T4 and cortisol levels. Moreover, in male SLE belugas, a weak significant positive association was found between T3 and Σ34PBDE concentrations in skin. Our findings suggest that stress (i.e., elevated skin cortisol levels) along with organohalogen exposure (mainly PBDEs) may be associated with thyroid hormone level perturbations in skin of cetaceans.

Emerging investigator series: nontargeted screening of aryl hydrocarbon receptor agonists in endangered beluga whales from the St. Lawrence Estuary: beyond legacy contaminants.

The elevated concentrations of organohalogen contaminants in the endangered St. Lawrence Estuary (SLE) belugas have prompted the hypothesis that aryl hydrocarbon receptor (AhR) activity may be a contributor towards their potential adverse effects. While indirect associations between AhR and contaminant levels have been reported in SLE beluga tissues, AhR activity was never directly measured. Using bioassays and nontargeted analysis, this study contrasted AhR activity and agonist profiles between pooled tissue extracts of endangered SLE and non-threatened Arctic belugas. Tissue extracts of SLE belugas exhibited significantly higher overall AhR activity than that of Arctic belugas, with a 2000s SLE beluga liver extract exerting significantly higher activity than blubber extracts of SLE and Arctic belugas from the same time period. Contrary to our expectations, well-known AhR agonists detected by nontargeted analysis, including polychlorinated biphenyls (PCBs), were only minor contributors to the observed AhR activity. Instead, Tox21 suspect screening identified more polar chemicals, such as dyes and natural indoles, as potential contributors. Notably, the natural product bromoindole was selectively detected in SLE beluga liver at high abundance and was further confirmed as an AhR agonist. These findings highlighted the significance of the AhR-mediated toxicity pathway in belugas and underscored the importance of novel AhR agonists, particularly polar compounds, in its induction.

Halogenated flame retardant exposure pathways in urban-adapted gulls: Are atmospheric routes underestimated?

Urban-adapted gulls can be exposed to flame retardants while foraging in landfills where elevated concentrations of polybrominated diphenyl ethers (PBDEs) and other halogenated flame retardants (HFRs) have frequently been measured in air. However, the contribution of atmospheric exposure has largely been overlooked compared to dietary exposure in birds and other wildlife. The overall objective of this study was to investigate the contribution of atmospheric exposure pathways relative to diet for PBDEs and other HFRs in ring-billed gulls (Larus delawarensis) nesting in the densely populated Montreal area (QC, Canada). Miniature passive air samplers (PASs) were deployed on the back of wild-caught ring-billed gulls for ten days. Concentrations of PBDEs and other HFRs were determined in PASs carried by ring-billed gulls as well as their lungs, stomach content, liver, preen oil, and onto the surface of their feathers. We evaluated the atmospheric and dietary exposure routes for the most abundant HFRs in samples using a structural equation model implemented in a Bayesian framework. Results indicated that lung concentrations of BDE-28 increased with its levels in air determined using bird-borne PASs. No association was found between BDE-28 concentrations in lungs and liver, whereas BDE-209 concentrations in liver increased with those in lungs. Moreover, BDE-28 and -47 concentrations in liver increased with those on feather surface, while liver BDE-47 concentrations were also positively related with those in stomach content. These findings suggested that, in addition to dietary exposure, atmospheric exposure pathways through inhalation and co-ingestion during feather maintenance (preening) significantly contribute to the accumulation of PBDEs in liver of ring-billed gulls. Atmospheric exposure to HFRs should therefore be considered in future landfill-foraging wildlife species as a potential exposure route compared to the traditional dietary exposure pathway.

Impact of landfill characteristics on the atmospheric exposure to halogenated flame retardants in gulls.

Large amounts of consumer products containing halogenated flame retardants (HFRs) are disposed of annually in landfills, which may lead to significant releases of these semi-volatile contaminants into the environment. During their foraging activities in landfills, gulls can be exposed to elevated levels of HFRs in air. Ring-billed gulls (Larus delawarensis) breeding in the densely populated Montreal area (QC, Canada) are significantly exposed to air levels of polybrominated diphenyl ethers (PBDEs) in or in the vicinity of landfills. However, no information is currently available on the specific characteristics of these landfills that can modulate the atmospheric exposure of ring-billed gulls to HFRs. The objective of this study was to investigate how atmospheric exposure in ring-billed gulls to PBDEs and other HFRs is influenced by selected landfill characteristics (i.e., daily cover materials, waste types and tonnage). Miniature passive air samplers (PASs) combined with GPS dataloggers were deployed for ten days during six years on the back of wild-caught ring-billed gulls breeding in the Montreal area. Atmospheric levels of several PBDEs and other HFRs determined in PASs were found to increase with the presence probability of gulls in the two largest landfills using automotive shredder residues as daily cover material. Weather variables including relative humidity and wind speed had a weak influence on atmospheric levels of HFRs in the bird-borne PASs. Our results suggest that automotive shredder residues represent a significant emission source of HFRs into the air of landfills, thus influencing atmospheric exposure of gulls and other birds foraging in these sites.

Novel flame retardants in urban-feeding ring-billed gulls from the St. Lawrence River, Canada.

This study investigated the occurrence of a comprehensive suite of polybrominated diphenyl ethers (PBDEs) and current-use flame retardants (FRs) in ring-billed gulls breeding in a highly industrialized section of the St. Lawrence River, downstream from Montreal (QC, Canada). Despite major point-sources and diffuse contamination by FRs, nearly no FR data have been reported in birds from this area. Bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (BEHTBP) was detected in 89% of ring-billed gull livers (mean: 2.16 ng/g ww; max: 17.6 ng/g ww). To our knowledge, this is the highest detection frequency and highest concentrations reported thus far in any avian species or populations. Dechlorane Plus (DP) isomers were also particularly abundant (anti-DP detected in 100% and syn-DP in 93% of livers). Other detected FR compounds (3-14% detection) included 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB), hexachlorocyclopentenyl-dibromocyclooctane (HCDBCO) and ß-1,2-dibromo-4-(1.2-dibromoethyl)-cyclohexane (ß-TBECH). Mean BDE-209 (57.2 ± 12.2 ng/g ww) in ring-billed gull livers was unexpectedly high for this midtrophic gull species, exceeding levels reported in several apex raptors such as peregrine falcons. BDE-209's relative contribution to ∑PBDEs was on average 25% (exceeding BDE-47 and BDE-99) and contrasted with profiles typically reported for fish-eating gull species. The present study highlighted preoccupying gaps in upcoming FR regulations and stressed the need for further investigation of the sources of FR exposure in highly urbanized areas.

Occurrence and temporal trends of industrial antioxidants and UV absorbents in the endangered St. Lawrence Estuary beluga whale (Delphinapterus leucas).

Elevated contaminant exposure has been identified as a stressor that has negative impacts on the health and recovery of the endangered St. Lawrence Estuary (SLE) beluga (Delphinapterus leucas) population. However, the accumulation of many groups of contaminants of emerging concern is still unknown in the SLE beluga. The objective of this study was to investigate the occurrence and temporal trends (2000-2017) of synthetic phenolic antioxidants (SPAs), secondary aromatic amines (Ar-SAs), benzotriazole UV stabilizers (BZT-UVs), and organic UV filters (UVFs) in the blubber (n = 69) and liver (n = 80) of SLE beluga carcasses recovered in the SLE. The SPA 2,6-di-tert-butyl-1,4-benzoquinone (BHTQ) was the most prevalent contaminant in the blubber (detection frequency: 86 %; median: 71.1 ng/g wet weight (ww)) and liver (50 %; 12.2 ng/g ww) of SLE belugas. In the blubber, 2-hydroxy-4-methoxybenzophenone (BP3) (36 %; 3.15 ng/g ww) and 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethyl butyl)phenol (UV329) (49 %; 6.84 ng/g ww) were the most frequently detected UVFs and BZT-UVs, respectively. Ar-SAs were not detected in most of the blubber and liver samples. Blubber accumulated higher levels of BHTQ and UV329 than liver, whereas the levels of BP3 were greater in the liver. Male SLE beluga accumulated greater concentrations of UV329 in blubber compared to females. These results indicated that the accumulation of BHTQ, UV329 and BP3 in SLE belugas is tissue- and sex-specific. BHTQ showed a decreasing trend in the blubber (2000-2017) of male SLE beluga, whereas no significant trend of this contaminant was found in females. UV329 showed no discernible temporal trend. This study established a baseline for the future monitoring of SPAs, Ar-SAs, BZT-UVs and UVFs in belugas and other marine mammals.

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.