Factors influencing lead, mercury and other trace element exposure in birds from metal mining areas.

Non-ferrous metal mining is considered one of the largest sources of toxic metal released to the environment and may threaten ecosystems, notably biota. We explored how birds that inhabit non-ferrous metal mining sites are exposed to mercury, lead, and other trace elements by analyzing their feathers and verifying which factors may influence element concentrations in feathers. We sampled a total of 168 birds, representing 26 species, with different feeding habits and migration patterns in a non-polluted reference site and two historical metal mining areas: Almadén, which is considered one of the most heavily mercury-contaminated sites worldwide, and the Sierra Madrona mountains where lead has been mined since ancient times. The quantification of aluminum (Al), arsenic (As), barium (Ba), beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), selenium (Se), thorium (Th), thallium (Tl), uranium (U), vanadium (V) and zinc (Zn) was performed by inductively coupled plasma mass spectrometry (ICP-MS). Feather analysis revealed contamination by Hg and Pb, in Almadén and Sierra Madrona, respectively. We found that granivorous birds had the lowest feather Hg levels compared to those found in omnivorous, insectivorous, and piscivorous species, whereas feather Pb was about twice as high in granivores and omnivores, than in insectivorous and piscivorous birds. We also found differences among study sites in 13 elements and confirmed the influence of feather age, migratory patterns of the birds, and external deposition of elements, on metal concentrations in the feathers. Our results highlight that despite the cessation of metal mining in the study areas, local avifauna are being exposed to Hg and Pb from abandoned mines and old tailings sites, indicating that appropriate measures are needed to protect biota from overexposure to these toxic metals.

Metal Changes in Pre- and Post-metamorphic Wood Frog (Lithobates sylvaticus) Tadpoles: Implications for Ecotoxicological Studies.

The development of anuran larvae from hatchling through metamorphosis is a particularly sensitive life stage that often is studied to assess adverse effects of water pollution, such as metal contamination. As an integral part of the food chain, high metal exposure and accumulation in developing anuran larvae may not only affect their survival but also pose a threat to secondary consumers. The presented work examines metal accumulation in wood frog tadpoles (Lithobates sylvaticus) before and after reaching metamorphic climax at emergence of the forelimbs. Metal levels were determined in whole tadpoles pre- and post-metamorphic climax in tadpole tissue excluding the stomach and intestines, as well as in water, via inductively coupled plasma-mass spectrometry. Wood frog tadpoles concentrated metals in their gut coil, with a rapid decline coincident with metamorphic climax. Tadpoles raised in a diluted bitumen-contaminated environment had higher levels of vanadium, molybdenum and cadmium, but not at levels expected to negatively impact development. In conclusion, metal accumulation in wood frog tadpoles varies greatly depending on developmental stage surrounding metamorphic climax. Metabolic changes and intestinal remodelling must be considered when studying pollutants in developing anuran larvae.

Enclosure design for flock-level, chronic exposure of birds to air contaminant mixtures.

The objective of this study was to design an enclosure suitable for studying the ecotoxicological effects of vehicle emissions on groups of wild birds without compromising welfare. Two, adjacent enclosures sheltered from sunlight, wind and rain, were bird-proofed and wrapped with thick polyethylene sheeting. Emissions were directed into the treatment enclosure from the exhaust of a light-duty gasoline truck, using flexible, heat-proof pipe, with joins sealed to prevent leakage. During active exposure, the engine was idled for 5 h/day, 6 days/week for 4 weeks. Fans maintained positive pressure (controls) and negative pressure (treatment), preventing cross-contamination of enclosures and protecting investigators. Four sets of passive, badge-type samplers were distributed across each enclosure, measuring nitrogen dioxide, sulfur dioxide and volatile organic compounds (NO2, SO2 and VOCs, respectively), and were complemented by active monitors measuring VOCs and particulate matter (2.5 µm diameter, PM2.5). We found that the concentrations of NO2, SO2 and PM2.5 were not different between treatment and control enclosures. Volatile organic compounds (e.g. benzene, toluene, ethylbenzene and xylenes) were approximately six times higher in the treatment enclosure than control (13.23 and 2.13 µg m-1, respectively). In conclusion, this represents a successful, practical design for studying the effects of sub-chronic to chronic exposure to realistic mixtures of vehicle exhaust contaminants, in groups of birds. Recommended modifications for future research include a chassis dynamometer (vehicle treadmill), to better replicate driving conditions including acceleration and deceleration.

Biomarker Sensitivity to Vehicle Exhaust in Experimentally Exposed European Starlings.

The effects of vehicle-related emissions on health has been a long-standing question in human health sciences; however, the toxicology of chronic exposure to environmentally relevant concentrations of these complex mixtures has not been characterized in wild birds. Adult European starlings (Sturnus vulgaris) were exposed to vehicle emissions, with combined benzene, toluene, ethylbenzene, and xylenes (BTEX) concentrations totaling 13.3 µg/m3 over 20 days of exposure for 5 h per day. Exposed birds had significantly lower cell-mediated immunity (measured using phytohaemagglutinin skin test, p < 0.0001), thyroxine (T4, p = 0.042), and glutathione (GSH, p = 0.034) concentrations than control birds. There was no difference in body condition, antibody response to vaccination, triiodothyronine (T3), hepatic biotransformation (7-ethoxyresorufin-O-deethylase activity), or oxidative stress (thiobarbituric acid-reactive substances and ratios of reduced to oxidized GSH) or organ masses between exposed and control birds. This study supports findings of previous studies examining wild birds exposed to these air contaminants and raises concern that environmentally relevant concentrations of common urban volatile pollutants may have measurable effects on health.

European Starlings (Sturnus vulgaris) As Sentinels of Urban Air Pollution: A Comprehensive Approach from Noninvasive to Post Mortem Investigation.

Urban, traffic-related air pollution remains a concern to health-care and environmental professionals, with mounting evidence connecting diverse disease conditions with exposure. Wildlife species such as European starlings (Sturnus vulgaris) cohabit urban neighborhoods and may serve as sentinels for these contaminants. In this novel approach, we use passive, personal-type air samplers to provide site-specific measurements of nitrogen dioxide (NO2), sulfur dioxide (SO2) and volatile organic compounds (VOCs, such as benzene, toluene, ethylbenzene, and xylenes, or BTEX), and account for the effects of confounding environmental factors when teasing out the responses to exposure. This study examines biomarkers of exposure to predominately traffic-related, urban air contaminants in European starlings, including morphometric measurements, immunotoxicology, oxidative stress and hepatic detoxification, and analyses responses in the context of multilayered factors including year, hatch date, weather and location, confirming that this experimental approach and the selected health indicators can be used for comparing locations with different levels of contaminants.

Inhaling Benzene, Toluene, Nitrogen Dioxide, and Sulfur Dioxide, Disrupts Thyroid Function in Captive American Kestrels (Falco sparverius).

Research investigating the effects of air contaminants on biota has been limited to date. Captive adult female American kestrels (Falco sparverius) were exposed to a mixture of benzene (0.6 ppm), toluene (1 ppm), nitrogen dioxide (NO2; 2 ppm) and sulfur dioxide (SO2; 5.6 ppm), in a whole-body inhalation chamber. Thyroid axis responses to meet metabolic demands were examined through thyroid histology, plasma thyroxine (T4), and triiodothyronine (T3), and hepatic outer ring deiodination (T4-ORD). Plasma free (F) T3 and T4 were measured at baseline, and at 9 days and 18 days of exposure, whereas total (T) T3 and TT4, thyroid histology and hepatic T4-ORD were determined at the final 18 day exposure. Inhalation of these contaminants significantly suppressed plasma FT4 and TT4, and depleted follicular colloid and increased epithelial cell height at 18 days, and significantly altered the temporal pattern of plasma FT4. Significant histological changes in the follicular colloid:epithelial cell height ratio indicated sustained T4 production and release by the thyroid glands. There was no effect on plasma FT3, TT3, or hepatic T4-ORD. We hypothesize that contaminant-related activation of the hypothalamus-pituitary-thyroid axis in the kestrels increased elimination of plasma T4 through Phase II enzymes. Further research is required to test this hypothesis in wild birds.

Small mammals as sentinels of oil sands related contaminants and health effects in northeastern Alberta, Canada.

The extraction of bitumen in areas of northeastern Alberta (Canada) has been associated with the release of complex mixtures of metals, metalloids, and polycyclic aromatic compounds (PACs) to the environment. To mitigate effects on ecosystems, Canadian legislation mandates that disturbed areas be reclaimed to an ecologically sustainable state after active operations. However, as part of reclamation activities, exposure to, and effects on wildlife living in these areas is not generally assessed. To support successful reclamation, the development of efficient methods to assess exposure and health effects in potentially exposed wildlife is required. In the present study, we investigated the usefulness of two native mammalian species (deer mouse Peromyscus maniculatus, and meadow vole Microtus pennsylvanicus) as sentinels of oil sands related contaminants by examining biomarkers of exposure and indicators of biological costs. Tissue residues of 31 metals and metalloids in kidneys and muscle, activity of the hepatic detoxification enzyme EROD (as a biomarker of exposure to organic contaminants), body condition, and the relative mass of liver, kidney, spleen, and testes were compared in animals from one reclaimed area and a reference site. Deer mice from the reclaimed site had higher renal levels of Co, Se and Tl compared to animals from the reference site, which was associated with reduced body condition. Lower testis mass was another feature that distinguished mice from the reclaimed site in comparison to those from the reference site. One mouse and one vole from the reclaimed site also showed increased hepatic EROD activity. In marked contrast, no changes were evident for these variables in meadow voles. Our results show that deer mouse is a sensitive sentinel species and that the biomarkers and indicators used here are efficient means to detect local contamination and associated biological effects in native mammals inhabiting reclaimed areas on active oil sands mine sites. These field-derived findings can be used by risk assessors to fill possible data gaps for mammalian wildlife in science-based environmental risk assessments for oil and gas projects.

Stress response, biotransformation effort, and immunotoxicity in captive birds exposed to inhaled benzene, toluene, nitrogen dioxide, and sulfur dioxide.

In the oil sands of Alberta, Canada, toxicology research has largely neglected the effects of air contaminants on biota. Captive Japanese quail (Coturnix c. japonica) and American kestrels (Falco sparverius) were exposed to mixtures of volatile organic compounds and oxidizing agents (benzene, toluene, NO2 and SO2) in a whole-body inhalation chamber, to test for toxicological responses. Hepatic biotransformation measured through 7-ethoxyresorufin-O-dealkylase (EROD) tended to be increased in exposed kestrels (p=0.06) but not in quail (p=0.15). Plasma corticosterone was increased in the low dose group for quail on the final day of exposure (p=0.0001), and midway through the exposure period in exposed kestrels (p=0.04). For both species, there was no alteration of T and B-cell responses, immune organ mass, or histology of immune organs (p>0.05). This study provides baseline information valuable to complement toxicology studies and provides a better understanding of potential health effects on wild avifauna.

Health of domestic mallards (Anas platyrhynchos domestica) following exposure to oil sands process-affected water.

Bitumen extraction from the oil sands of northern Alberta produces large volumes of process-affected water that contains substances toxic to wildlife. Recent monitoring has shown that tens of thousands of birds land on ponds containing this water annually, creating an urgent need to understand its effects on bird health. We emulated the repeated, short-term exposures that migrating water birds are thought to experience by exposing pekin ducks (Anas platyrhynchos domestica) to recycled oil sands process-affected water (OSPW). As indicators of health, we measured a series of physiological (electrolytes, metabolites, enzymes, hormones, and blood cells) and toxicological (metals and minerals) variables. Relative to controls, juvenile birds exposed to OSPW had higher potassium following the final exposure, and males had a higher thyroid hormone ratio (T3/T4). In adults, exposed birds had higher vanadium, and, following the final exposure, higher bicarbonate. Exposed females had higher bile acid, globulin, and molybdenum levels, and males, higher corticosterone. However, with the exception of the metals, none of these measures varied from available reference ranges for ducks, suggesting OSPW is not toxic to juvenile or adult birds after three and six weekly, 1 h exposures, but more studies are needed to know the generality of this result.

Seasonal and biogeographical patterns of gastrointestinal parasites in large carnivores: wolves in a coastal archipelago.

Parasites are increasingly recognized for their profound influences on individual, population and ecosystem health. We provide the first report of gastrointestinal parasites in gray wolves from the central and north coasts of British Columbia, Canada. Across 60 000 km(2), wolf feces were collected from 34 packs in 2005-2008. At a smaller spatial scale (3300 km(2)), 8 packs were sampled in spring and autumn. Parasite eggs, larvae, and cysts were identified using standard flotation techniques and morphology. A subset of samples was analysed by PCR and sequencing to identify tapeworm eggs (n=9) and Giardia cysts (n=14). We detected ≥14 parasite taxa in 1558 fecal samples. Sarcocystis sporocysts occurred most frequently in feces (43·7%), followed by taeniid eggs (23·9%), Diphyllobothrium eggs (9·1%), Giardia cysts (6·8%), Toxocara canis eggs (2·1%), and Cryptosporidium oocysts (1·7%). Other parasites occurred in ≤1% of feces. Genetic analyses revealed Echinococcus canadensis strains G8 and G10, Taenia ovis krabbei, Diphyllobothrium nehonkaiense, and Giardia duodenalis assemblages A and B. Parasite prevalence differed between seasons and island/mainland sites. Patterns in parasite prevalence reflect seasonal and spatial resource use by wolves and wolf-salmon associations. These data provide a unique, extensive and solid baseline for monitoring parasite community structure in relation to environmental change.

Pathological, immunological and biochemical markers of subchronic arsenic toxicity in rats.

Subchronic exposure to arsenic in rats was investigated to identify sensitive indicators of subclinical toxicity in rats. Immunological, pathological, and biochemical bioindicators were examined in rats exposed to arsenic in their drinking water. Juvenile male Wistar rats were allocated to four treatment groups receiving 0, 0.4, 4, and 40 ppm of arsenite in drinking water for 18 wks. Besides daily monitoring for clinical signs of adverse health effects, clinical biochemistry, B-cell-mediated and innate immune responses, plus gross, and histopathology were examined. In vitro tests of oxidative damage to basic cellular constituents, lipids, proteins, and nucleic acids, were measured using thiobarbituric acid reacting substances (TBARS) assays, protein carbonyl formation, and 8-hydroxydeoxyguanosine (8-OHdG), respectively. Clinical changes in the rats were limited to decreased feed and water intake in the high- (40 ppm) dose group (P < 0.05), however, growth rate was not affected. Serum biochemical changes occurred in blood urea nitrogen, K(+) , Cl(-) , and alanine aminotransferase (ALT) from arsenic exposure. Immunotoxicity was evident through a dose-dependent suppression of the secondary antibody-mediated response to a T-cell-dependent antigen, keyhole limpet hemocyanin (KLH). Histopathology of the liver revealed marked fatty infiltration and vacuolization particularly evident in periacinar hepatocytes. This pattern of toxicopathology in the high-exposure group may be related to the significantly higher (P < 0.05) oxidative stress, demonstrated through lipid peroxidation (TBARS assay) in the rats exposed to 40 ppm arsenite. The present study revealed that young, growing rats exposed to arsenic for 18 wks tolerated exposures up to 4 ppm. At higher doses, there was evidence of hepatotoxicity, humoral immunity was compromised, and an adverse effect on hepatic organelle and cell membranes was evident through a dose dependent increased in oxidative stress.

The effect of a high-selenium lentil diet on cardiovascular risk markers in an arsenic-exposed population.

Chronic arsenic exposure is associated with a number of systemic diseases, including cardiovascular disease. Selenium has been shown to promote arsenic excretion from the body. We investigated if a high-selenium lentil diet has an effect on blood pressure and plasma lipid levels in an arsenic-exposed population by conducting a 6-month randomized controlled dietary intervention trial with 405 participants.

Cross-continental comparison of parasite communities in a wide-ranging carnivore suggests associations with prey diversity and host density.

Parasites are integral to ecosystem functioning yet often overlooked. Improved understanding of host-parasite associations is important, particularly for wide-ranging species for which host range shifts and climate change could alter host-parasite interactions and their effects on ecosystem function.Among the most widely distributed mammals with diverse diets, gray wolves (Canis lupus) host parasites that are transmitted among canids and via prey species. Wolf-parasite associations may therefore influence the population dynamics and ecological functions of both wolves and their prey. Our goal was to identify large-scale processes that shape host-parasite interactions across populations, with the wolf as a model organism.By compiling data from various studies, we examined the fecal prevalence of gastrointestinal parasites in six wolf populations from two continents in relation to wolf density, diet diversity, and other ecological conditions.As expected, we found that the fecal prevalence of parasites transmitted directly to wolves via contact with other canids or their excreta was positively associated with wolf density. Contrary to our expectations, the fecal prevalence of parasites transmitted via prey was negatively associated with prey diversity. We also found that parasite communities reflected landscape characteristics and specific prey items available to wolves.Several parasite taxa identified in this study, including hookworms and coccidian protozoans, can cause morbidity and mortality in canids, especially in pups, or in combination with other stressors. The density-prevalence relationship for parasites with simple life cycles may reflect a regulatory role of gastrointestinal parasites on wolf populations. Our result that fecal prevalence of parasites was lower in wolves with more diverse diets could provide insight into the mechanisms by which biodiversity may regulate disease. A diverse suite of predator-prey interactions could regulate the effects of parasitism on prey populations and mitigate the transmission of infectious agents, including zoonoses, spread via trophic interactions.

Toxicity and immune system effects of dietary deltamethrin exposure in tiger salamanders (Ambystoma tigrinum).

One theory proposed to explain the global declines in amphibian populations involves contaminant-induced immune alteration and subsequent increased susceptibility to infectious disease. The goal of this study was twofold, to (1) study acute oral toxicity of deltamethrin (cyclopropanecarboxylic acid, 3-(2,2-dibromoethenyl)-2,2-dimethyl cyano(3-phenoxyphenyl)methyl ester) in tiger salamanders (Ambystoma tigrinum), and (2) evaluate whether the insecticide deltamethrin produces immunosuppression in these animals. In the acute toxicity study, tiger salamanders receiving single doses of deltamethrin ranging from 1 to 35 mg/kg displayed intention tremors, hypersalivation, ataxia, choreoathetosis (writhing), severe depression (immobility with minimal response to stimuli), and death. For acute effects, based on clinical signs, the median lethal dose (LD(50)) and lowest observed adverse effect level (LOAEL) were estimated to be 5 to 10 mg/kg and 1 mg/kg, respectively. The LOAEL in animals dosed 3 times per week for 4 wk was 400 microg/kg/d. The endpoints for the immunotoxicity study included lymphoid organ mass and histopathology, hematological variables, and functional assays of phagocytosis, oxidative burst, and lymphoblastic transformation. Tiger salamanders in 4 treatment groups (0, 4, 40, or 400 microg/kg/d) were dosed with deltamethrin via the diet 3 times per week for 4 wk. Deltamethrin exposure resulted in increased liver mass, packed cell volume, and total plasma protein concentration, but these effects were not dose dependent. The relative mass of kidney and spleen, plasma albumin and globulin concentrations, and circulating leukocyte numbers were not affected by deltamethrin exposure, nor were phagocytosis, oxidative burst, and lymphoblastic transformation. This study shows that at moderate levels of exposure, deltamethrin may be neurotoxic to tiger salamanders. However, based on the immune assays considered in this study there was no evidence of immunosuppression from dietary exposure to environmentally relevant concentrations of deltamethrin. In light of these findings, it is unlikely that exposure to environmental concentrations of deltamethrin has produced immunosuppression and contributed to the emergence of iridovirus outbreaks in tiger salamander populations.

Response of a Small Mammal Population Postremediation for an In Situ Oil Pipeline Blowout on the Athabasca Oil Sands.

Two releases from steam assisted gravity drainage (SAGD) wellheads occurred 3 yr apart. To track recovery of the affected areas, red-backed voles were studied 1 and 4 yr later, using population estimates, hepatic detoxification effort, body condition, and tissue metal levels as bioindicators of site recovery. From years 1 to 4, higher ethoxyresorufin-O-deethylase induction was no longer evident, capture rate was lower, and body lead residues were no longer (inversely) correlated with body condition. Environ Toxicol Chem 2019;38:1542-1548. © 2019 SETAC.

Effects of inhalation exposure to a binary mixture of benzene and toluene on vitamin a status and humoral and cell-mediated immunity in wild and captive American kestrels.

Benzene and toluene are representative volatile organic compounds (VOC) released during production, storage, and transportation associated with the oil and gas industry and are chemicals of concern, as they are released in greater and possibly more biologically significant concentrations than other compounds. Most studies of air pollution in high oil and gas activity areas have neglected to consider risks to birds, including top-level predators. Birds can be used as highly sensitive monitors of air quality and since the avian respiratory tract is physiologically different from a rodent respiratory tract, effects of gases cannot be safely extrapolated from rodent studies. Wild and captive male American kestrels were exposed for approximately 1 h daily for 28 d to high (rodent lowest-observed-adverse-effect level [LOAEL] of 10 ppm and 80 ppm, respectively) or environmentally relevant (0.1 ppm and 0.8 ppm, respectively) levels of benzene and toluene. Altered immune responses characteristic of those seen in mammalian exposures were evident in kestrels. A decreased cell-mediated immunity, measured by delayed-type hypersensitivity testing, was evident in all exposed birds. There was no effect on humoral immunity. Plasma retinol levels as measured by high-performance liquid chromatography (HPLC) analysis were decreased in wild and captive kestrels exposed to the rodent LOAEL for combined benzene and toluene. This study indicates that American kestrels are sensitive to combined benzene and toluene. The study also illustrates the need for reference concentrations for airborne pollutants to be calculated, including sensitive endpoints specific to birds. Based on these findings, future studies need to include immune endpoints to determine the possible increased susceptibility of birds to inhaled toxicants.

The design, construction, and operation of a whole-body inhalation chamber for use in avian toxicity studies.

Environmental risk assessments are broadening to include evaluations of avian species exposed to gaseous and particulate materials (Mineau, 2002b; Irvine, 2004; Carmalt, 2005). Since the avian respiratory tract is fundamentally different from the respiratory tract of rodents, the effects of gaseous materials on birds cannot validly be extrapolated from data derived from rodent exposure studies (Briant & Driver, 1992; Brown et al., 1997). To address the lack of avian-specific lowest observable effect levels used to calculate reference concentrations for airborne pollutants, a system was designed to facilitate research on inhalation toxicology in small birds. Birds have long been used as early indicators of poor air quality (Brown et al., 1997), and various chambers have been designed for head only exposures of larger birds (Briant & Driver, 1992). Smaller birds with short tracheal lengths and hooked beaks however require less restrictive exposure apparatus, thus warranting the proposed design. The chamber described in this article was designed to accommodate a small falcon, the American kestrel, a species frequently used in toxicological risk assessments (Wiemeyer & Lincer, 1987a; Smits & Bortolotti, 2001; Bortolotti et al., 2003; Fisher et al., 2006). To accomplish this, a 41-L closed inhalation system capable of exposing 12 adult American kestrels was constructed primarily of galvanized steel, polyvinyl chloride, and copper tubing. Humidified air was passed over the birds and subsequently decontaminated by an activated carbon filter and released to a HEPA filtration system. The proposed inhalation chamber was successfully used in 2005 and 2006 to expose a total of 55 male American kestrels to benzene and toluene. Measurements of various biochemical endpoints associated with benzene and toluene toxicity allowed us to study the effects of airborne pollutants on small nondomesticated birds in a controlled laboratory setting.

Immunological development in nestling American kestrels Falco sparverius: post-hatching ontogeny of the antibody response.

Avian research involving examination of immune function or testing of immunocompetence in wild birds has been based upon information on Galliforms, (chicken and quail) even though they are precocial, whereas most wild species with which ecologists, biologists and toxicologists work are altricial; blind, naked and completely dependent at hatching. Here we begin to address this gap in knowledge, offering insight into the early, post-hatching, humoral immune response in an altricial bird, the American kestrel (Falco sparverius). Over two breeding seasons, nestling kestrels were immunized with a non-pathogenic antigen, dinitrophenol keyhole limpet hemocyanin (DNP-KLH), between 3 and 9 days post-hatching and boostered 6 days later. Background levels, primary and secondary immune responses were measured using an enzyme linked immunosorbent assay. The specificity of our laboratory produced rabbit, anti-kestrel antibody was determined using a double immunodiffusion assay. Results showed the rabbit antiserum to have specific anti-kestrel IgG activity. Birds as young as three days old could successfully mount an antibody response, the magnitude of which increased with age at first vaccination. Early immunization did not compromise growth rate, nor did it affect the maximum secondary response. Comparatively, adult kestrels immunized during the same season and following the same protocol, had antibody levels four times higher than those of the nestlings.

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).

Effects of exposure to naphthenic acids in tree swallows (Tachycineta bicolor) on the Athabasca oil sands, Alberta, Canada.

Naphthenic acids (NAs) are a group of carboxylic acids that are of particular concern to the steadily growing oil sands mining industry of Alberta, Canada, because they become highly concentrated in the water used for oil sands extraction and are toxic to aquatic biota and mammals. Upon mine closure, vast amounts of process-affected water will need to be reclaimed and proven safe for wildlife colonizing reclaimed areas. The effects of exposure to NAs have not been investigated in avian species. To address this void, tree swallow (Tachycineta bicolor) nestlings were dosed with NAs while being reared normally by their free-ranging parents on a site in the vicinity of the oil sands. Nestlings received 1.5 mg NAs/day (approximately 0.075 g/kg body mass) from d 7 to d 13 of age, which represented a 10-fold "worst exposure" scenario. Nestling growth, hematocrit, blood biochemistry, organ weights, and ethoxyresorufin O-deethylase (EROD) activity were unaffected by NAs. The only change detected on histopathological evaluation of major organs was an increase in extramedullary erythropoiesis in the liver. These findings indicate that nestling tree swallows can successfully tolerate short-term exposures to environmentally realistic concentrations of NAs. However, this study did not investigate the chronic or reproductive toxicity of NAs. More research needs to be conducted to complete this initial assessment, to determine environmental risks on reclaimed areas where birds will be breeding and where their exposure to NAs could extend for several weeks.