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.

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

Following the ban of many historically-used flame retardants (FRs), numerous replacement chemicals have been produced and used in products, with some being identified as environmental contaminants. One of these replacement flame retardants is 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (DBE-DBCH; formerly abbreviated as TBECH), which to date has not been identified for risk assessment and potential regulation. DBE-DBCH technical mixtures consist largely of α- and β-diastereomers with trace amounts of γ- and δ-DBE-DBCH.

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.

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.

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.

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.

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.

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-, β- and γ-HBCDD), and to determine if feather concentrations are related to physiological biomarkers.

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).

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.

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).

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 β-DBE-DBCH, the isomer found most prominently in animal tissue, affects androgen-dependent behavior of breeding American kestrels (Falco sparverius).

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.

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.

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.

The flame retardant β-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 β-1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (β-TBECH). The β-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).

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.

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.

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.

Embryonic exposure to the polybrominated diphenyl ether mixture, DE-71, affects testes and circulating testosterone concentrations in adult American kestrels (Falco sparverius).

Polybrominated diphenyl ethers (PBDEs) are additive flame retardants that are environmentally persistent and bioaccumulative. The developmental effects of in ovo exposure to environmentally relevant levels of the PBDE technical mixture, DE-71, on male reproductive physiology in captive American kestrels (Falco sparverius) was determined. Males were exposed in ovo by direct maternal transfer to DE-71 at three mean concentrations of 289 ng/g ww (low exposure), 1131 ng/g ww (high-exposure), or background levels of 3 ng/g ww (control).

Multi-generational effects of polybrominated diphenylethers exposure: embryonic exposure of male American kestrels (Falco sparverius) to DE-71 alters reproductive success and behaviors.

Polybrominated diphenylethers (PBDEs) are additive flame-retardants that are environmentally persistent and bioaccumulative compounds of particular concern to species at high trophic levels, including predatory birds. The developmental effects of in ovo exposure to male birds at environmentally relevant levels of the PBDE technical mixture, DE-71, on reproductive success and behaviors using captive American kestrels (Falco sparverius) were determined. Males were exposed in ovo by direct maternal transfer to DE-71 and unintentionally to low concentrations of hexabromocyclododecane (HBCD) at three mean +/- standard error DE-71 concentrations of 288.