Prioritization of Pesticides for Assessment of Risk to Aquatic Ecosystems in Canada and Identification of Knowledge Gaps.

Pesticides can enter aquatic environments via direct application, via overspray or drift during application, or by runoff or leaching from fields during rain events, where they can have unintended effects on non-target aquatic biota. As such, Fisheries and Oceans Canada identified a need to prioritize current-use pesticides based on potential risks towards fish, their prey species, and habitats in Canada. A literature review was conducted to: (1) Identify current-use pesticides of concern for Canadian marine and freshwater environments based on use and environmental presence in Canada, (2) Outline current knowledge on the biological effects of the pesticides of concern, and (3) Identify general data gaps specific to biological effects of pesticides on aquatic species. Prioritization was based upon recent sales data, measured concentrations in Canadian aquatic environments between 2000 and 2020, and inherent toxicity as represented by aquatic guideline values. Prioritization identified 55 pesticides for further research nationally. Based on rank, a sub-group of seven were chosen as the top-priority pesticides, including three herbicides (atrazine, diquat, and S-metolachlor), three insecticides (chlorpyrifos, clothianidin, and permethrin), and one fungicide (chlorothalonil). A number of knowledge gaps became apparent through this process, including gaps in our understanding of sub-lethal toxicity, environmental fate, species sensitivity distributions, and/or surface water concentrations for each of the active ingredients reviewed. More generally, we identified a need for more baseline fish and fish habitat data, ongoing environmental monitoring, development of marine and sediment-toxicity benchmarks, improved study design including sufficiently low method detection limits, and collaboration around accessible data reporting and management.

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

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

Changes in plasma biochemistry in breeding ring-billed gulls: Effects of anthropogenic habitat use and contaminant exposure.

Gulls (Larids) have become successful at exploiting anthropogenic areas for foraging. However, little is known on the health implications of using anthropogenic habitats and on the associated exposure to environmental contaminants, particularly with respect to plasma biochemistry that is routinely used to diagnose physiological disorders and diseases. The objective of the present study was to investigate the effects of anthropogenic habitat use and exposure to ubiquitous halogenated flame retardants (HFRs) on plasma biochemistry of urban-breeding ring-billed gulls (Larus delawarensis) from one of the largest colonies in North America. Miniature GPS dataloggers were used to characterize foraging habitat use of individual gulls (n = 39) at the regional scale (urban, waste management facilities, agricultural fields, and St. Lawrence River) in the Montreal area (QC, Canada), and plasma was analyzed for a suite of biochemical measures (waste products, lipids, glucose, ions, proteins, and enzymes) and HFRs. Several confounding biological and environmental variables were also assessed including sex, body condition, time spent fasting while incubating, plasma thyroid hormone levels, time of day, capture date, and ambient temperature. As ring-billed gulls (males and females combined) spent more time foraging in urban areas, their plasma concentrations of cholesterol, albumin and activity of alkaline phosphatase increased significantly. Moreover, as the gulls spent more time foraging in agricultural fields, their plasma concentrations of phosphorous and activity of aspartate aminotransferase increased significantly. Only the activity of aspartate aminotransferase was significantly positively related to plasma HFR concentrations (PBDEs and dechlorane-related compounds). Time spent fasting while incubating, plasma thyroid hormone levels, body condition, time of day, and capture date were significantly related to certain plasma biochemical measures. The present results suggest that both the use of anthropogenic habitats for foraging and exposure to HFRs may affect the plasma biochemistry of ring-billed gulls breeding in the densely-populated Montreal area, suggesting potential adverse health effects for avian wildlife living in highly urbanized environments.

Is the current-use flame retardant, DBE-DBCH, a potential obesogen? Effects on body mass, fat content and associated behaviors in American kestrels.

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 ß isomer at the environmentally relevant dose of 0.239 ng ß-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); ß-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 ß-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 ß-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.

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

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

Multiple stressors including contaminant exposure and parasite infection predict spleen mass and energy expenditure in breeding ring-billed gulls.

Daily energy expenditure (DEE) in animals is influenced by many factors although the impact of stressors remains largely unknown. The objective of this study was to determine how multiple physiological stressors (parasite infection and contaminant exposure) and natural challenges (energy-demanding activities and weather conditions) may affect DEE in nesting ring-billed gulls (Larus delawarensis) exposed to high concentrations of persistent organic contaminants (POPs). Physical activity, temperature, gastrointestinal parasitic worm abundance, relative spleen mass, plasma thyroid hormone levels and liver concentrations of POPs were determined; field metabolic rate (FMR) was used as a measure of DEE. For females, FMR was best explained by the percent of time spent in nest-site attendance and exposure to temperatures below their lower critical limit (65% of variation); 32% was also explained by relative spleen mass. In males, FMR was best explained by the number of hours spent in nest site attendance and either relative spleen mass or liver concentrations of tetra-brominated diphenyl ethers (tetra-BDEs) (55% of variation). Relative spleen mass, as an important factor relating to FMR, was best explained by models with a combination of parasite abundance (Diplostomum for females and Eucoleus for males) in a negative relationship, and liver POP concentrations (p,p'-DDE for females and tetra-BDEs for males) in a positive relationship (34%, 55% of variation for females and males, respectively). This study demonstrates that immune activity may be an important factor affecting energy expenditure in ring-billed gulls, and that contaminants and parasite abundance may have both a direct and/or indirect influence on FMR.

Disruption of thyroxine and sex hormones by 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (DBE-DBCH) in American kestrels (Falco sparverius) and associations with reproductive and behavioral changes.

1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (DBE-DBCH - formerly TBECH) is an emerging brominated flame retardant (BFR) pollutant with androgen potentiating ability and other endocrine disrupting effects in birds and fish. The objectives of this study were to determine the effects of exposure to environmentally-relevant levels of DBE-DBCH on circulating levels of thyroid and sex steroid hormones in American kestrels, and if hormonal concentrations were related to previously reported changes in reproductive success and courtship behaviors. Sixteen kestrel pairs were exposed to 0.239ng ß-DBE-DBCH/g kestrel/day by diet, based on concentrations in wild bird eggs, from 4 weeks before pairing until the chicks hatched (mean 82 d), and were compared with vehicle-only-exposed control pairs (n=15). As previously reported, DBE-DBCH concentrations were not detected in tissue or eggs of these birds, nor were any potential metabolites, despite the low method limits of detection (≤0.4ng/g wet weight), suggesting it may be rapidly metabolized and/or eliminated by the kestrels. Nevertheless, exposed kestrels demonstrated changes in reproduction and behavior, indicating an effect from exposure. During early breeding, males were sampled at multiple time points at pairing and during courtship and incubation; females were blood sampled at pairing only; both sexes were sampled at the end of the season. All comparisons are made to control males or control females, and the relative differences in hormone concentrations between treatment and control birds, calculated separately for each sex, are presented for each time point. Males exposed to ß-DBE-DBCH demonstrated significantly (p=0.05) lower concentrations of total thyroxine (TT4) overall, that were 11-28% lower than those of control males at the individual sampling points, yet significantly higher (p=0.03) concentrations of free thyroxine (FT4), that were 5-13% higher than those of control males at the individual sampling points; females had similar concentrations of TT4 and FT4 at the time of pairing, and T4 was similar in both sexes at the end of the breeding season. Testosterone (T) concentrations in the treatment males were significantly higher during early (85%) and mid-courtship (30%) (time*treatment p=0.001), whereas females demonstrated a reduction in T at the time of pairing (17%, p=0.05). In the treatment females, concentrations of 17ß-estradiol (E2) showed a non-significant decrease (20%) and were positively correlated with T concentrations (p=0.03); E2 concentrations were below quantification limits in males. For males, some variation in T was also significantly associated with their sexual behavior (p<0.001) and FT4 concentrations (p=0.01). For females, there was no relationship between hormones measured at pairing and subsequent sexual behaviors or reproductive measures. This study demonstrates that exposure to ß-DBE-DBCH at levels that are likely below those experienced by wild birds, affects the thyroid and sex steroid axes in birds and thus may be a contaminant of concern for wildlife warranting further research.

Transfer of hexabromocyclododecane flame retardant isomers from captive American kestrel eggs to feathers and their association with thyroid hormones and growth.

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-, ß- 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-, ß- 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-, ß- 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 ß- 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 ß- or γ-HBCDD concentrations (wi = 0.50, 0.30 respectively), while feather concentrations of ß- and γ-HBCDD were influenced by growth parameters (rectrix length: wi = 0.61; tibiotarsus length: wi = 0.28). These results suggest that feather α-HBCDD concentrations may reflect internal body burdens, whereas ß- 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 (T3:T4; p = 0.020), demonstrating for the first time that feather concentrations may be used to model the effect of body burdens on physiological endpoints.

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.

Sex-specific changes in thyroid gland function and circulating thyroid hormones in nestling American kestrels (Falco sparverius) following embryonic exposure to polybrominated diphenyl ethers by maternal transfer.

High concentrations of polybrominated diphenyl ethers (PBDEs) accumulate in predatory birds. Several PBDE congeners are considered thyroid disruptors; however, avian studies are limited. The authors examined circulating thyroid hormones and thyroid gland function of nestling American kestrels (Falco sparverius) at 17 d to 20 d of age, following embryonic exposure by maternal transfer only to environmentally relevant levels of PBDEs (DE-71 technical mixture). Nestlings were exposed to in ovo sum (Σ) PBDE concentrations of 11 301 ± 95 ng/g wet weight (high exposure), 289 ± 33 ng/g wet weight (low exposure), or 3.0 ± 0.5 ng/g wet weight (controls, background exposure). Statistical comparisons are made to controls of the respective sexes and account for the relatedness of siblings within broods. Circulating concentrations of plasma total thyroxine (TT4 ) and total triiodothyronine (TT3 ) in female nestlings were significantly influenced overall by the exposure to DE-71. Following intramuscular administration of thyroid-stimulating hormone, the temporal response of the thyroid gland in producing and/or releasing TT4 was also significantly affected by the females' exposure to DE-71. The altered availability of T4 for conversion to T3 outside of the gland and/or changes in thyroid-related enzymatic activity may explain the lower TT3 concentrations (baseline, overall) and moderately altered temporal TT3 patterns (p = 0.06) of the treatment females. Controlling for the significant effect on TT3 levels of the delayed hatching of treatment females, baseline TT3 levels were significantly and positively correlated with body mass (10 d, 15 d, 20 d), with PBDE-exposed females generally being smaller and having lower TT3 concentrations. Given that exposure concentrations were environmentally relevant, similar thyroidal changes and associated thyroid-mediated processes relating to growth may also occur in wild female nestlings. Environ Toxicol Chem 2016;35:2084-2091. © 2016 SETAC.

Exposure to the androgenic brominated flame retardant 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane alters reproductive and aggressive behaviors in birds.

Detected in environmental samples, 1,2-dibromo-4-(1,2-dibromoethyl) cyclohexane (DBE-DBCH) is a bioaccumulative isomer of a current-use brominated flame retardant. All 4 structural isomers are androgen agonists; however, little toxicological information exists for this compound. The objective of the present study was to determine if ß-DBE-DBCH, the isomer found most prominently in animal tissue, affects androgen-dependent behavior of breeding American kestrels (Falco sparverius). The authors hypothesized that if ß-DBE-DBCH acts as an androgen agonist in kestrels, androgen-dependent behaviors (i.e., copulation, courtship, aggression) would increase and behaviors inhibited by androgens (i.e., parental care behaviors) would decrease. Sixteen captive experimental kestrel pairs were exposed to 0.239 ng ß-DBE-DBCH/g kestrel/d by diet from 4 wk prior to pairing until their nestlings hatched (mean 82 d) and compared with vehicle only-exposed control pairs (n = 15). Androgen-dependent behaviors were significantly increased in ß-DBE-DBCH-exposed birds, consistent with the authors' hypothesis. These behavioral changes included copulation and other sexual behaviors in males and females and aggression in males, suggesting that ß-DBE-DBCH may have acted like an androgen agonist in these birds. Parental behaviors were not reduced in exposed birds as predicted, although dietary exposure had ceased before chicks hatched. Further assessment of ß-DBE-DBCH is recommended given these behavioral changes and the previously reported reproductive changes in the same birds.

Field Metabolic Rate Is Dependent on Time-Activity Budget in Ring-Billed Gulls (Larus delawarensis) Breeding in an Anthropogenic Environment.

Environmental and behavioral factors have long been assumed to affect variation in avian field metabolic rate (FMR). However, due to the difficulties in measuring continuous behavior of birds over prolonged periods of time, complete time-activity budgets have rarely been examined in relation to FMR. Our objective was to determine the effect of activity (measured by detailed time-activity budgets) and a series of extrinsic and intrinsic factors on FMR of the omnivorous ring-billed gull (Larus delawarensis). The experiment was conducted during the incubation period when both members of the pair alternate between attending the nest-site and leaving the colony to forage in aquatic and anthropogenic environments (city, agricultural). FMR was determined using the doubly labeled water method. Time-activity budgets were extrapolated from spatio-temporal data (2-5 days) obtained from bird-borne GPS data loggers. Gulls had low FMRs compared to those predicted by allometric equations based on recorded FMRs from several seabird species. Gulls proportioned their time mainly to nest-site attendance (71% of total tracking time), which reduced FMR/g body mass, and was the best variable explaining energy expenditure. The next best variable was the duration of foraging trips, which increased FMR/g; FMR/g was also elevated by the proportion of time spent foraging or flying (17% and 8% of tracking time respectively). Most environmental variables measured did not impact FMR/g, however, the percent of time birds were subjected to temperatures below their lower critical temperature increased FMR. Time-activity budgets varied between the sexes, and with temperature and capture date suggesting that these variables indirectly affected FMR/g. The gulls foraged preferentially in anthropogenic-related habitats, which may have contributed to their low FMR/g due to the high availability of protein- and lipid-rich foods. This study demonstrates that activities were the best predictors of FMR/g in ring-billed gulls, thus providing strong support for this long-standing theory in bioenergetics.

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.

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

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.

Changes in the incubation by American kestrels (Falco sparverius) during exposure to the polybrominated diphenyl ether (PBDE) mixture DE-71.

Polybrominated diphenyl ethers (PBDE) are persistent environmental pollutants that have been detected in wildlife globally. American kestrels exposed to the commercial PBDE mixture DE-71 have previously demonstrated reduced reproductive success and behaviors during courtship and brood rearing; however, it remains unknown whether DE-71 affects incubation. During breeding, captive kestrels were exposed to the DE-71 mixture dissolved in safflower oil at two environmentally relevant concentrations (low: 283.5 ± 48.2, high: 1104.8 ± 124.5 ng/g wet weight [ww]) via diet for an average of 75 d. Unexpected low in ovo concentrations of hexabromocyclododecane (HBCD) were also detected (low: 3 ± 1 ng/g ww, high: 16 ± 3 ng/g ww). All comparisons are made to control pairs. Kestrel pairs in the low- and high-exposure groups experienced longer incubation periods with increasing exposure to ΣPBDE and some individual congeners. As incubation progressed, pairs exposed to DE-71 had significantly lower nest temperatures, which were on average 19% lower in low-exposure nests and 35% lower in high-exposure nests during late incubation. The DE-71 exposed pairs (low and high) also demonstrated significantly reduced incubation constancy (defined as percent of temperature readings above the maximum daily ambient temperature) during early incubation compared to controls. Nest temperatures (all pairs) and incubation constancy (high pairs) during early incubation (d 1-3) were significantly and positively associated with the proportion of eggs that hatched per pair. Higher incubation constancy and incubating nest temperatures in the low-exposure group were associated with markedly less egg weight loss by mid-incubation. These findings demonstrate that exposure to PBDE significantly affected kestrels during incubation, a critical period for embryonic development.

The flame retardant ß-1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane: fate, fertility, and reproductive success in American kestrels (Falco sparverius).

Captive American kestrels (Falco sparverius) were exposed via diet during reproduction to an environmentally relevant concentration of ß-1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (ß-TBECH). The ß-TBECH isomer was injected into the food source at a daily dosing concentration of 0.239 ng/g kestrel/day (22 pairs); control birds were exposed via diet to the safflower oil vehicle only (24 pairs). Eight pairs in each group were exposed for four weeks and sacrificed for tissue analysis; the remaining pairs completed their breeding cycle, with exposure ceasing at the end of incubation (82 days). α- and ß-TBECH appeared to be rapidly metabolized and/or eliminated from fat, liver, and plasma; both isomers and potential hydroxylated metabolites of ß-TBECH (plasma) were undetected. Notwithstanding, compared to controls, pairs exposed to ß-TBECH laid fewer eggs (p = 0.019) and laid lighter eggs (successful eggs: p = 0.009). Exposed pairs also demonstrated poorer egg fertility (p = 0.035) although testis mass and histology were similar among males. Reductions in egg production and fertility resulted in decreased hatchling success (p = 0.023). The ß-TBECH-exposed pairs also produced fewer males overall (p = 0.009), which occurred concurrently with increased estradiols maternally deposited in eggs (p = 0.039). These findings demonstrate that ß-TBECH may be detrimental for breeding in wild birds receiving similar exposure levels.

Dietary exposure to technical hexabromocyclododecane (HBCD) alters courtship, incubation and parental behaviors in American kestrels (Falco sparverius).

Hexabromocyclododecane (HBCD) is a high production volume brominated flame retardant that has been detected in the environment and wildlife at increasing concentrations. This study was designed to determine potential effects of dietary exposure to environmentally relevant levels of HBCD on behavior during reproduction in captive American kestrels. Twenty kestrel pairs were exposed to 0.51 µg technical HBCD g(-1) kestrel d(-1) from 4 weeks prior to pairing until chicks hatched (~75 d). Ten pairs of controls received the safflower oil vehicle only and were used for comparison. During the courtship period the chitter-calls were reduced in both sexes (p=0.038) and females performed fewer bonding displays (p=0.053). Both sexes showed a propensity to be less active than controls during courtship. The reduction in male courtship behavior was correlated with reduced courtship behaviors of females (p=0.008) as well as reduced egg mass (p=0.019). During incubation, nest temperatures of treatment pairs were lower at mid-incubation (p=0.038). HBCD-exposed males performed fewer key parental behaviors when rearing nestlings, including entering the nest-box, pair-bonding displays and food-retrievals. HBCD-exposed females appeared to compensate for the reduced parental behavior of their mates by performing these same behaviors more frequently than controls (p=0.004, p=0.027, p=0.025, respectively). This study demonstrates that HBCD affects breeding behavior in American kestrels throughout the reproductive season and behavioral alterations were linked to reproductive changes (egg size). This is the first study to report HBCD effects on reproductive behavior in any animal model.

Diet exposure to technical hexabromocyclododecane (HBCD) affects testes and circulating testosterone and thyroxine levels in American kestrels (Falco sparverius).

Hexabromocyclododecane (HBCD) is a high-production-volume, brominated flame-retardant that is used in items such as polystyrene foams. HBCD has been detected in the environment, wildlife tissues and in humans globally with some of the highest recorded levels in predatory birds. This study examined the effects of exposure to environmentally relevant levels of HBCD on the reproductive physiology of captive male American kestrels (Falco sparverius), a predatory bird. Two sets of males were used: one group not housed with females (unpaired: nc=12, nHBCD=10) and the second group housed with females (breeding: nc=10, nHBCD=20). All treatment birds were exposed to 0.51 µg HBCD/g kestrel/day technical HBCD, and controls to safflower oil only, injected into their food during seasonal testicular development. Unpaired males were exposed for 3 weeks and euthanized for testicular analysis. Breeding males were exposed for 3 weeks prior to pairing and throughout the courtship period. The HBCD-exposed unpaired males had heavier testes (p≤0.017) and a trend towards more seminiferous tubules containing elongated spermatids (p=0.052). There was also a moderate increase in plasma testosterone concentrations (p=0.056) compared to controls. In breeding males, testosterone levels increased during courtship to culminate in higher levels than controls by the time the first egg was laid (p=0.010) and circulating free and total T4 was reduced throughout. The number of sperm cells reaching the perivitelline layer of the first egg for breeding males did not differ between the two groups. This study is the first report that HBCD exposure at environmentally relevant levels alters reproductive physiology in male birds and suggests that birds may be more sensitive to HBCD than mammals.

Reproductive changes in American kestrels (Falco sparverius) in relation to exposure to technical hexabromocyclododecane flame retardant.

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 ß- 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.