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Abstract The current-use brominated flame retardant, 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (DBE-DBCH), is capable of perturbing sex steroid and thyroid hormone pathways in vitro and in vivo. Chemicals with this capability may also disrupt metabolic processes and are candidate obesogens, but this potential has not yet been determined for DBE-DBCH. Our objective was to examine gross biomarkers of metabolic disruption in captive American kestrels. Birds were exposed by diet to the β isomer at the environmentally relevant dose of 0.239 ng β-DBE-DBCH/g kestrel/day, from 30 days (d) prior to pairing through until chicks hatched (82 d) (n = 30 breeding pairs) or for 28 d (n = 16 pre-breeding pairs), and were compared with vehicle-only exposed controls. Body mass was assessed throughout the breeding season at biologically relevant time points, flight and feeding behavior was measured in 5-min samples daily, and plasma triglycerides and cholesterol were assessed at d10 of brood rearing. Treated males were heavier than controls at pairing (p = 0.051), the final week of courtship (p = 0.061), and at d10 (p = 0.012) and d20 of brood rearing (p = 0.051); β-DBE-DBCH-exposed breeding females were similar in weight to control females. Treated birds tended to have higher plasma triglycerides (p = 0.078), which for females, was positively associated with body mass (p = 0.019). Heavier breeding males had higher plasma concentrations of testosterone and total thyroxine (p ≤ 0.046). Overall, both sexes exposed to β-DBE-DBCH demonstrated reduced flight behavior and increased feeding behavior during courtship. In the pre-breeding pairs, treated male and female kestrels had a higher percentage of body fat than respective controls (p = 0.045). These results demonstrate that β-DBE-DBCH elicited inappropriate fat and weight gain in adult American kestrels, consistent with their increased feeding, reduced flight activity and endocrine changes, and suggests that DBE-DBCH may be an obesogen warranting further research to test this hypothesis. Highlights • Captive birds gained more body fat (proportionally) when fed β-DBE-DBCH for 4 weeks. • Male American kestrels exposed to β-DBE-DBCH gained extra weight during breeding. • Plasma triglycerides marginally increased in female kestrels exposed to β-DBE-DBCH. • Relative to thyroid and sex hormones, treatment kestrels were heavier or flew less. • Results suggest more research needed to confirm DBE-DBCH as a possible obesogen. [ABSTRACT FROM AUTHOR]

Feathers are useful for monitoring contaminants in wild birds and are increasingly used to determine persistent organic pollutants. However, few studies have been conducted on birds with known exposure levels. We aimed to determine how well nestling feather concentrations reflect in ovo exposure to hexabromocyclododecane (α-, β- and γ-HBCDD), and to determine if feather concentrations are related to physiological biomarkers. Captive kestrels (n = 11) were exposed in ovo to maternally transferred HBCDD-isomers at concentrations of 127, 12 and 2 ng/g wet weight of α-, β- and γ-HBCDD (measured in sibling eggs), respectively, and compared to controls (n = 6). Nestling growth was monitored at 5 d intervals and circulating thyroid hormone concentrations assessed at d 20. Tail feathers were collected prior to the first molt and analyzed for HBCDD isomers. The mean ΣHBCDD concentration in feathers was 2405 pg/g dry weight (in exposed birds) and α-, β- and γ-HBCDD made up 32%, 13%, and 55%, respectively of the ΣHBCDD concentrations. This isomer distribution deviated from the typical dominance of α-HBCDD reported in vertebrate samples. Exposed chicks had significantly higher feather concentrations of β- and γ-HBCDD compared with controls ( p = 0.007 and p = 0.001 respectively), while α-HBCDD concentrations did not differ between the two groups. Feather concentrations of α-HBCDD were best explained by egg concentrations of β- or γ-HBCDD concentrations ( w i = 0.50, 0.30 respectively), while feather concentrations of β- and γ-HBCDD were influenced by growth parameters (rectrix length: w i = 0.61; tibiotarsus length: w i = 0.28). These results suggest that feather α-HBCDD concentrations may reflect internal body burdens, whereas β- and γ-HBCDD may be subject to selective uptake. The α-HBCDD concentrations in the feathers were negatively associated with the ratio of plasma free triiodothyronine to free thyroxine (T 3 :T 4 ; p = 0.020), demonstrating for the first time that feather concentrations may be used to model the effect of body burdens on physiological endpoints. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Accumulation and evidence of debromination of the flame retardant 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209) have been reported for biota, including raptorial birds, based on PBDE congener residues in tissues and eggs. However, in vivo studies with BDE-209-exposed birds are rare and unknown for a raptorial species. In the present study, males (n=22) of raptorial American kestrels (Falco sparverius) were exposed to 116,000ng of BDE-209 (high purity, >98%; in safflower oil) per day for 21days (~2,436,000ng total BDE-209 exposure over this uptake period), followed by a 25-day depuration period. Control males (n=11) received the safflower vehicle only. In the exposed birds, BDE-209 was quantifiable in all plasma (end of uptake and depuration period) as well as liver and fat (end of depuration only) samples. The mean (±SE) BDE-209 level in plasma was 1474±1145ng/g wet weight (ww) at the end of the uptake period, and was significantly (p<0.001) lower (88%) at 174±148ng/g ww after the 25day depuration period. This equates to a mean reduction rate of 52ng/g ww per day and a rough estimation of the BDE-209 half-life in plasma of approximately 14days. The mean (±SE) BDE-209 levels were 4668±6192ng/g ww in the fat, and 338±311ng/g ww in the liver, of exposed individuals, which were significantly (p≤0.001) greater than mean concentrations (25±20 in fat and 2.6±0.9ng/g ww in liver) in the control birds. In addition to BDE-209, lower brominated PBDE congeners, and mainly meta- and para-debromination products of BDE-209 were also quantified in plasma, liver and/or fat. We estimated based on the dose that at least 80% of the non-BDE-209 concentration in the kestrel tissues and plasma must be derived from BDE-209 debromination by the kestrels. Where quantifiable, lower brominated PBDE concentrations were significantly (0.023>p>0.001) higher in the exposed relative to the control bird samples (except for BDE-154 and -153 in fat). Additional PBDE congeners found in plasma included nona-BDEs (208, 207 and 206), followed by octa-BDEs (197, 196, 201 and 203), and in liver and/or fat, the hepta-BDEs 180 and 183 and BDE-153. Higher hepatic EROD activity (cytochrome P450 1A1 monooxygenase-mediation) in the exposed birds compared to control birds was strongly suggested to be PBDE-induced, and was consistent with BDE-209 and congener metabolism in the exposed kestrels. The mean EROD activity rate was 36.1pmol/min/mg protein relative to the (n=4) control birds whose activity was just above the detection limit (10.3pmol/min/mg protein). Overall, the results demonstrated that following diet exposure of kestrels to high purity BDE-209, uptake occurred as well as BDE-209 degradation via debromination to lower brominated PBDE congeners. [ABSTRACT FROM AUTHOR]

Recently, the ban of hexabromocyclododecane (HBCD), a high-production-volume flame retardant, was announced in Europe and North America. However, the effects of HCBD remain understudied in birds. The objectives of the present comparative effects study were to determine whether exposure to an HBCD technical mixture (HBCD-TM) altered avian reproductive measures at an environmentally relevant concentration. American kestrels were exposed daily by food to HBCD-TM, i.e., 0.51 µg HBCD/g kestrel/d; exposed kestrels laid eggs that had α-HBCD concentrations (163.5 ± 75.1 ng/g wet wt) tenfold greater than β- and γ-HBCD isomers, an isomer profile and concentrations similar to those of eggs of wild peregrine falcons ( Falco peregrinus). Concentrations of HBCD were not detected in the control kestrel eggs. In comparison with controls, the kestrels exposed to HBCD began to lay their eggs 6 d earlier and laid larger clutches of smaller eggs. The size of the eggs was inversely correlated with the in ovo α-HBCD concentrations. The smaller eggs of the HBCD exposed kestrels also lost more weight by midincubation, suggesting increased eggshell porosity since eggshell thickness was comparable. Generally birds that lay more eggs and lay earlier in the breeding season gain the advantage of better hatching and fledging success, yet the kestrels exposed to HBCD failed to have better reproductive success than the control birds. These reproductive changes were a function of HBCD exposure, likely through changes in food consumption, with possible impacts on, for example, reproductive behavior and/or alterations in thyroid hormones. Environ. Toxicol. Chem. 2011;30:2570-2575. © 2011 SETAC [ABSTRACT FROM AUTHOR]

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

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 (TT 4 ) and triiodothyronine (TT 3 ), tocopherol, retinol and oxidative status (isoprostanes). The summed concentrations of the top 5 PBDEs (Σ 5 ) (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) (0–7.5 ng/g ww) > tris(2-chloroisopropyl) phosphate (TCIPP) (0.1–5.5 ng/g ww) > tris(2-chloroethyl) phosphate (TCEP) (0.02–2.0 ng/g ww) > tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) (0–1.0 ng/g ww). Within the GL-SLR, the urban nestlings’ diet had significantly more terrestrial sources (greater δ 13 C values) than the broader, more aquatic-based diet of rural peregrines. Dietary source (δ 13 C) was significantly associated with concentrations of Σ 5 PBDE, BDE-209, EHTBB, and 2,2–4,4′,5,5′-hexabromobiphenyl (BB-153), with trophic level (δ 15 N) also positively associated with BDE-209 levels. Compared to urban nestlings, the rural nestlings had significantly lower circulating concentrations of thyroxine (TT 4 ), triiodothyronine (TT 3 ), a greater proportion of TT 3 relative to TT 4 (TT 3 :TT 4 ), 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 TT 4 , 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. [ABSTRACT FROM AUTHOR]