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At least 217 records · Page 12Linked to original sources
USGS2011

Oxidative stress response of Forster's terns (Sterna forsteri) and Caspian terns (Hydroprogne caspia) to mercury and selenium bioaccumulation in liver, kidney, and brain

Bioindicators of oxidative stress were examined in prebreeding and breeding adult and chick Forster's terns ( Sterna forsteri ) and in prebreeding adult Caspian terns ( Hydroprogne caspia ) in San Francisco Bay, California. Highest total mercury (THg) concentrations (mean±standard error;μg/g dry wt) in liver (17.7±1.7), kidney (20.5±1.9), and brain (3.0±0.3) occurred in breeding adult Forster's terns. The THg concentrations in liver were significantly correlated with hepatic depletion of reduced glutathione (GSH), increased oxidized glutathione (GSSG):GSH ratio, and decreased hepatic gamma-glutamyl transferase (GGT) activity in adults of both tern species. Prefledging Forster's tern chicks with one-fourth the hepatic THg concentration of breeding adults exhibited effects similar to adults. Total mercury-related renal GSSG increased in adults and chicks. In brains of prebreeding adults, THg was correlated with a small increase in glucose-6-phosphate dehydrogenase (G-6-PDH) activity, suggestive of a compensatory response. Brain THg concentrations were highest in breeding adult Forster's terns and brain tissue exhibited increased lipid peroxidation as thiobarbituric acid-reactive substances, loss of protein bound thiols (PBSH), and decreased activity of antioxidant enzymes, GSSG reductase (GSSGrd), and G-6-PDH. In brains of Forster's tern chicks there was a decrease in total reduced thiols and PBSH. Multiple indicator responses also pointed to greater oxidative stress in breeding Forster's terns relative to prebreeding terns, attributable to the physiological stress of reproduction. Some biondicators also were related to age and species, including thiol concentrations. Enzymes GGT, G-6-PDH, and GSSGred activities were related to species. Our results indicate that THg concentrations induced oxidative stress in terns, and suggest that histopathological, immunological, and behavioral effects may occur in terns as reported in other species.

California↗
USGS2019

Influence of dissolved organic carbon on the acute toxicity of copper and zinc to White Sturgeon (Acipenser transmontanus) and a Cladoceran (Ceriodaphnia dubia)

We conducted acute lethality tests with white sturgeon (Acipenser transmontanus) and Ceriodaphnia dubia exposed to copper and zinc at dissolved organic carbon concentrations ranging from 0.5 to 5.5 mg/L. Dissolved organic carbon had minimal effects on zinc toxicity but did have a protective effect on acute copper toxicity, which was equal to that predicted by the copper biotic ligand model (BLM). The BLM‐adjusted copper median effect concentrations for A. transmontanus ranged from 2.4 to 8.2 mg/L.

Environmental Toxicology and Chemistry↗
USGS2019

Brodifacoum toxicity in American Kestrels (Falco sparverius) with evidence of increased hazard upon subsequent anticoagulant rodenticide exposure

A seminal question in ecotoxicology is the extent to which contaminant exposure evokes prolonged effects on physiological function and fitness. A series of studies were undertaken with American kestrels ingesting environmentally realistic concentrations of the second-generation anticoagulant rodenticide (SGAR) brodifacoum (BROD). Kestrels fed BROD at 0.3, 1.0 or 3.0 µg/g diet wet wt for 7 d exhibited dose-dependent hemorrhage, histopathological lesions and coagulopathy (prolonged prothrombin and Russell’s viper venom times). Following termination of a 7 d exposure to 0.5 µg BROD/g diet, prolonged blood clotting time returned to baseline values within a week, but BROD residues in liver and kidney (terminal half-life estimates >50 d) persisted during the 28 d recovery period. In order to examine the hazard of sequential AR exposure, kestrels were exposed to either the firstgeneration AR chlorophacinone (CPN; 1.5 µg/g diet) or the SGAR BROD (0.5 µg/g diet) for 7 d, and following a recovery period, were challenged with a low dose of CPN (0.75 µg/g diet) for 7 d. In BROD-exposed kestrels, the challenge exposure clearly prolonged prothrombin time compared to naïve controls and kestrels previously exposed to CPN. These data provide evidence that the SGAR BROD may have prolonged effects that increase toxicity of subsequent AR exposure. As free-ranging predatory and scavenging wildlife are often repeatedly exposed to ARs, such protracted toxicological effects need to be considered in hazard and risk assessments.

Environmental Toxicology and Chemistry↗
USGS2020

Bioaccumulation and toxicity of cadmium, copper, nickel, and zinc and their mixtures to aquatic insect communities

We describe 2 artificial stream experiments that exposed aquatic insect communities to zinc (Zn), copper (Cu), and cadmium (year 2014) and to Zn, Cu, and nickel (year 2015). The testing strategy was to concurrently expose insect communities to single metals and mixtures. Single-metal tests were repeated to evaluate the reproducibility of the methods and year-to-year variability. Metals were strongly accumulated in sediments, periphyton, and insect (caddisfly) tissues, with the highest concentrations occurring in periphyton. Sensitive mayflies declined in metal treatments, and effect concentrations could be predicted effectively from metal concentrations in either periphyton or water. Most responses were similar in the replicated tests, but median effect concentration values for the mayfly Rhithrogena sp. varied 20-fold between the tests, emphasizing the difficulty comparing sensitivities across studies and the value of repeated testing. Relative to the single-metal responses, the toxicity of the mixtures was either approximately additive or less than additive when calculated as the product of individual responses (response addition). However, even less-than-additive relative responses were sometimes greater than responses to similar concentrations tested singly. The ternary mixtures resulted in mayfly declines at concentrations that caused no declines in the concurrent single-metal tests. When updating species-sensitivity distributions (SSDs) with these results, the mayfly responses were among the most sensitive 10th percentile of available data for all 4 metals, refuting older literature placing mayflies in the insensitive portion of metal SSDs. Testing translocated aquatic insect communities in 30-d artificial streams is an efficient approach to generate multiple species effect values under quasi-natural conditions that are relevant to natural streams.

Environmental Toxicology and Chemistry↗
USGS2011

Toxicity of silicon carbide nanowires to sediment-dwelling invertebrates in water or sediment exposures

Silicon carbide nanowires (SiCNW) are insoluble in water. When released into an aquatic environment, SiCNW would likely accumulate in sediment. The objective of this study was to assess the toxicity of SiCNW to four freshwater sediment-dwelling organisms: amphipods ( Hyalella azteca ), midges ( Chironomus dilutus ), oligochaetes ( Lumbriculus variegatus ), and mussels ( Lampsilis siliquoidea ). Amphipods were exposed to either sonicated or nonsonicated SiCNW in water (1.0 g/L) for 48 h. Midges, mussels, and oligochaetes were exposed only to sonicated SiCNW in water for 96 h. In addition, amphipods were exposed to sonicated SiCNW in whole sediment for 10 d (44% SiCNW on dry wt basis). Mean 48-h survival of amphipods exposed to nonsonicated SiCNW in water was not significantly different from the control, whereas mean survival of amphipods exposed to sonicated SiCNW in two 48-h exposures (0 or 15% survival) was significantly different from the control (90 or 98% survival). In contrast, no effect of sonicated SiCNW was observed on survival of midges, mussels, or oligochaetes. Survival of amphipods was not significantly reduced in 10-d exposures to sonicated SiCNW either mixed in the sediment or layered on the sediment surface. However, significant reduction in amphipod biomass was observed with the SiCNW either mixed in sediment or layered on the sediment surface, and the reduction was more pronounced for SiCNW layered on the sediment. These results indicated that, under the experimental conditions, nonsonicated SiCNW in water were not acutely toxic to amphipods, sonicated SiCNW in water were acutely toxic to the amphipods, but not to other organisms tested, and sonicated SiCNW in sediment affected the growth but not the survival of amphipods.

Environmental Toxicology and Chemistry↗
USGS2020

Feeding ecology drives lead exposure of facultative and obligate avian scavengers in the eastern United States

Lead poisoning of scavenging birds is a global issue. However, the drivers of lead exposure of avian scavengers have been understood from the perspective of individual species, not cross‐taxa assemblages. We analyzed blood ( n = 285) and liver ( n = 226) lead concentrations of 5 facultative (American crows [ Corvus brachyrhynchos ], bald eagles [ Haliaeetus leucocephalus ], golden eagles [ Aquila chrysaetos ], red‐shouldered hawks [ Buteo lineatus ], and red‐tailed hawks [ Buteo jamaicensis ]) and 2 obligate (black vultures [ Coragyps atratus ] and turkey vultures [ Cathartes aura ] avian scavenger species to identify lead exposure patterns. Species and age were significant ( α < 0.05) predictors of blood lead exposure of facultative scavengers; species, but not age, was a significant predictor of their liver lead exposure. We detected temporal variations in lead concentrations of facultative scavengers (blood: median = 4.41 µg/dL in spring and summer vs 13.08 µg/dL in autumn and winter; p = <0.001; liver: 0.32 ppm in spring and summer vs median = 4.25 ppm in autumn and winter; p = <0.001). At the species level, we detected between‐period differences in blood lead concentrations of bald eagles ( p = 0.01) and red‐shouldered hawks during the winter ( p = 0.001). During summer, obligate scavengers had higher liver lead concentrations than did facultative scavengers (median = 1.76 ppm vs 0.22 ppm; p = <0.001). These data suggest that the feeding ecology of avian scavengers is a determinant of the degree to which they are lead exposed, and they highlight the importance of dietary and behavioral variation in determining lead exposure.

Alabama, Georgia, Maryland, New Jersey, New York, ↗
USGS2020

Acute and chronic toxicity of nickel and zinc to a laboratory cultured mayfly (Neocloeon triangulifer) in aqueous but fed exposures

Aquatic insects are poorly represented in water quality criteria, and previous studies have suggested a lack of sensitivity in acute toxicity tests despite observational studies demonstrating the contrary. Our objectives were to determine the toxicity of nickel (Ni) and zinc (Zn) to the mayfly Neocloeon triangulifer in fed acute (96-h) and chronic exposures to estimate aqueous effect concentrations while acknowledging the importance of dietary exposure for these insects. For the chronic tests, we conducted preliminary full–life cycle (~25–30 d) and subchronic (14 d) exposures to compare the relative sensitivity of the 2 test durations under similar conditions (i.e., feeding rates). Observing similar sensitivity, we settled on 14 d as the definitive test duration. Furthermore, we conducted experiments to determine how much food could be added to a given volume of water while minimally impacting dissolved metal recovery; a ratio of food dry mass to water volume (<0.005) achieved this. In the 14-d tests, we obtained a median lethal concentration and most sensitive chronic endpoint of 147 and 23 µg/L dissolved Ni (acute to chronic ratio [ACR] = 6.4), respectively, and 81 (mean value) and 10 µg/L dissolved Zn (ACR = 8.1), respectively. The acute values are orders of magnitude lower than previously published values for mayflies, probably most importantly due to the presence of dietary exposure but also potentially with some influence of organism age and test temperature.

Environmental Toxicology and Chemistry↗
USGS2020

Acute and chronic toxicity of sodium nitrate and sodium sulfate to several freshwater organisms in water-only exposures

Elevated nitrate (NO3) and sulfate (SO4) in surface water are of global concern, and studies are needed to generate toxicity data to develop environmental guideline values for NO3 and SO4. The present study was designed to fill existing gaps in toxicity databases by determining the acute and/or chronic toxicity of NO3 (tested as NaNO3) to a unionid mussel (Lampsilis siliquoidea), a midge (Chironomus dilutus), a fish (rainbow trout, Oncorhynchus mykiss), and 2 amphibians (Hyla versicolor and Lithobates sylvaticus), and to determine the acute and/or chronic toxicity of SO4 (tested as Na2SO4) to 2 unionid mussels (L. siliquoidea and Villosa iris), an amphipod (Hyalella azteca), and 2 fish species (fathead minnow, Pimephales promelas and O. mykiss). Among the different test species, acute NO3 median effect concentrations (EC50s) ranged from 189 to >883 mg NO3‐N/L, and chronic NO3 20% effect concentrations (EC20s) based on the most sensitive endpoint ranged from 9.6 to 47 mg NO3‐N/L. The midge was the most sensitive species, and the trout was the least sensitive species in both acute and chronic NO3 exposures. Acute SO4 EC50s for the 2 mussel species (2071 and 2064 mg SO4/L) were similar to the EC50 for the amphipod (2689 mg SO4/L), whereas chronic EC20s for the 2 mussels (438 and 384 mg SO4/L) were >2‐fold lower than the EC20 of the amphipod (1111 mg SO4/L), indicating the high sensitivity of mussels in chronic SO4 exposures. However, the fathead minnow, with an EC20 of 374 mg SO4/L, was the most sensitive species in chronic SO4 exposures whereas the rainbow trout was the least sensitive species (EC20 > 3240 mg SO4/L). The high sensitivity of fathead minnow was consistent with the finding in a previous chronic Na2SO4 study. However, the EC20 values from the present study conducted in test water containing a higher potassium concentration (3 mg K/L) were >2‐fold greater than those in the previous study at a lower potassium concentration (1 mg K/L), which confirmed the influence of potassium on chronic Na2SO4 toxicity to the minnow.

Environmental Toxicology and Chemistry↗
USGS2020

Emerging and historical contaminants detected in desert rodents collected near a low‐level radioactive waste site

In an effort to determine contaminant presence, concentrations, and movement from a low‐level radioactive waste (LLRW) burial disposal site to ecosystems in the surrounding area, a study was developed to assess concentrations of per‐ and polyfluoroalkyl substances (PFAS), polychlorinated biphenyls (PCBs), and tritium. To complete this assessment small mammals, vegetation, soil, and insect samples were collected from areas within and adjacent to the Beatty, Nevada, LLRW site and from a reference area located approximately 3 km south of the LLRW site. Samples underwent analysis via liquid chromatography tandem mass spectrometry, gas chromatography mass spectrometry, or scintillation spectroscopy depending on the analyte of interest. Small mammal tissues showed maximum concentrations of over 1700 ng/g for PFAS, 1600 ng/g for PCBs, and 10 000 Bq/kg for tritium. The primary contaminants found in soil samples were PCBs, with maximum concentrations exceeding 25 ng/g. Trace amounts of PFAS were also detected in soils and insects. Only qualitative data were obtained from vegetation samples because of the complex matrix of the dominant plant species (creosote bush; Larrea tridentata [Sessé & Moc. ex DC.] Coville). Overall, these data indicate the presence of various anthropogenic contaminants in the ecosystem surrounding the LLRW area, but additional analyses are necessary to confirm the sources and migration pathways of PFAS and PCBs in this hyperarid environment. Environ Toxicol Chem 2020;00:1–8. © 2020 SETAC

Nevada↗
USGS2020

Primary sources of polycyclic aromatic hydrocarbons to streambed sediment in Great Lakes tributaries using multiple lines of evidence

Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread and potentially toxic contaminants in Great Lakes (USA/Canada) tributaries. The sources of PAHs are numerous and diverse, and identifying the primary source(s) can be difficult. The present study used multiple lines of evidence to determine the likely sources of PAHs to surficial streambed sediments at 71 locations across 26 Great Lakes Basin watersheds. Profile correlations, principal component analysis, positive matrix factorization source‐receptor modeling, and mass fractions analysis were used to identify potential PAH sources, and land‐use analysis was used to relate streambed sediment PAH concentrations to different land uses. Based on the common conclusion of these analyses, coal‐tar–sealed pavement was the most likely source of PAHs to the majority of the locations sampled. The potential PAH‐related toxicity of streambed sediments to aquatic organisms was assessed by comparison of concentrations with sediment quality guidelines. The sum concentration of 16 US Environmental Protection Agency priority pollutant PAHs was 7.4–196 000 µg/kg, and the median was 2600 µg/kg. The threshold effect concentration was exceeded at 62% of sampling locations, and the probable effect concentration or the equilibrium partitioning sediment benchmark was exceeded at 41% of sampling locations. These results have important implications for watershed managers tasked with protecting and remediating aquatic habitats in the Great Lakes Basin.

Indiana, Michigan, Minnesota, New York, Ohio, Wisc↗
USGS2020

Factors affecting sampling strategies for design of an effects‐directed analysis for endocrine‐active chemicals

Effects‐directed analysis (EDA) is an important tool for identifying unknown bioactive components in a complex mixture. Such an analysis of endocrine‐active chemicals (EACs) from water sources has promising regulatory implications but also unique logistical challenges. We propose a conceptual EDA (framework) based on a critical review of EDA literature and concentrations of common EACs in waste and surface waters. Required water volumes for identification of EACs under this EDA framework were estimated based on bioassay performance (in vitro and in vivo bioassays), limits of quantification by mass spectrometry (MS), and EAC water concentrations. Sample volumes for EDA across the EACs showed high variation in the bioassay detectors, with genistein, bisphenol A, and androstenedione requiring very high sample volumes and ethinylestradiol and 17β‐trenbolone requiring low sample volumes. Sample volume based on the MS detector was far less variable across the EACs. The EDA framework equation was rearranged to calculate detector “thresholds,” and these thresholds were compared with the literature EAC water concentrations to evaluate the feasibility of the EDA framework. In the majority of instances, feasibility of the EDA was limited by the bioassay, not MS detection. Mixed model analysis showed that the volumes required for a successful EDA were affected by the potentially responsible EAC, detection methods, and the water source type, with detection method having the greatest effect on the EDA of estrogens and androgens. The EDA framework, equation, and model we present provide a valuable tool for designing a successful EDA.

Environmental Toxicology and Chemistry↗
USGS2020

Temperature‐related responses of an invasive mussel and 2 unionid mussels to elevated carbon dioxide

Zebra mussels (Dreissena polymorpha) have exacerbated the decline of native freshwater mussels (Order Unionida) in North America since their arrival in the 1980s. Options for controlling invasive mussels, particularly in unionid mussel habitats, are limited. Previously, carbon dioxide (CO2) showed selective toxicity for zebra mussels, relative to unionids, when applied in cool water (12 °C). We first determined 96 h lethal concentrations of CO2 at 5 and 20 °C to zebra mussels and responses of juvenile plain pocketbook (Lampsilis cardium). Next, we compared the time to lethality for zebra mussels at 5, 12, and 20 °C during exposure to partial pressure of CO2 (PCO2) 110¬–120 atmospheres (atm; 1 atm = 101.325 kPa) and responses of juvenile plain pocketbook and fragile papershell (Leptodea fragilis). We found efficacious CO2 treatment regimens at each temperature that were minimally lethal to unionids. At 5 °C, plain pocketbook survived 96 h exposure to the highest PCO2 treatment (139 atm). At 20 °C, the 96 h LC10 (lethal concentration to 10% of animals) for plain pocketbook [173 atm PCO2, 95% confidence interval (CL) 147–198 atm] was higher than the LC99 for zebra mussels (118 atm PCO2, CL 109–127 atm). Lethal time to 99% mortality (LT99) of zebra mussels in 110 to 120 atm PCO2 ranged from 100 h at 20 °C to 300 h at 5 °C. Mean survival of juvenile unionids exceeded 85% in LT99 CO2 treatments at all temperatures. Short-term infusion of 100 to 200 atm PCO2 at a range of water temperatures could reduce biofouling by zebra mussels with limited adverse effects on unionid mussels.

Environmental Toxicology and Chemistry↗
USGS2020

Investigation on endocrine disruption of the larval lampricide 3-trifluoromethyl-4-nitrophenol: Short-term reproduction assay with fathead minnow (Pimephales promelas) under flow-through conditions

3‐Trifluoromethyl‐4‐nitrophenol (TFM) has been used for more than 60 yr to control the invasive parasitic sea lamprey ( Petromyzon marinus ) in the Great Lakes Basin (USA/Canada). In the early 1990s, researchers reported that TFM induced vitellogenin in fish and that TFM was an agonist for the rainbow trout estrogen receptor. To support continued registration of TFM for sea lamprey control, regulatory agencies required further testing to evaluate potential endocrine disruption effects. Fathead minnow ( Pimephales promelas ) were exposed to TFM at measured concentrations of 0.0659, 0.181, 0.594, 1.79, and 5.11 mg active ingredient (a.i.)/L for 21 d. No‐observable‐ and lowest‐observable‐effect concentrations (NOEC and LOEC, respectively) were determined to be 1.79 mg/L or greater for each endpoint. Male survival in the highest treatment group was reduced relative to the controls. Percentage of egg fertility was reduced in the highest treatment group, resulting in an estimated NOEC of 1.79 mg/L. Whereas no effect on the gonadosomatic index (GSI) was observed for males, female GSI was increased in the 5.11‐mg/L treatment. Vitellogenin production was not altered relative to the controls for all TFM treatment groups. However, female testosterone was elevated in the 5.11‐mg/L treatment. The results suggest that prolonged exposure to TFM at concentrations exceeding 1.79 mg/L has the potential to disrupt endocrine function. Biologically relevant effects were found at the highest exposure concentration following a 21‐d exposure. However, the duration of exposure in our study is not consistent with typical treatment durations (12 h) for sea lamprey control. Environ Toxicol Chem 2020;39:1599–1607. © 2020 SETAC

Environmental Toxicology and Chemistry↗
USGS2020

Legacy and contaminants of emerging concern (CECs) in tree swallows along an agricultural to industrial gradient: Maumee River, OH

Exposure to multiple classes of contaminants, both legacy and contaminants of emerging concern (CECs), were assessed in tree swallow ( Tachycineta bicolor ) tissue and diet samples from 6 sites along the Maumee River, Ohio, USA, to understand both exposure and possible effects of exposure to those CECs for which there are little avian data. The 6 sites represented a gradient from intensive agriculture upstream to highly urbanized and industrial landscapes downstream; 1 or 2 remote Wisconsin lakes were assessed for comparative purposes. Cytochrome P450 induction, DNA damage, and thyroid function were also assessed relative to contaminant exposure. Bioaccumulative CECs, such as polybrominated diphenyl ethers (PBDEs) and perfluorinated substances, did not follow any upstream to downstream gradient; but both had significantly greater concentrations along the Maumee River than at the remote lake sites. Greater exposure to PBDEs was apparent in swallows at or near wastewater‐treatment facilities than at other sites. Total polychlorinated biphenyl and total polycyclic aromatic hydrocarbon concentrations were greater in swallows at downstream locations compared to upstream sites and were associated with higher ethoxyresorufin‐ O ‐dealkylase activity. Few herbicides or nonorganochlorine insecticides were detected in swallow tissues or their food, except for atrazine and its metabolite desethylatrazine. Few pharmaceuticals and personal care products were detected except for DEET and iopamidol. Both were detected in most liver samples but not in eggs, as well as detected at the remote lake sites. This is one of the most comprehensive assessments to date of exposure and effects of a wide variety of CECs in birds.

Ohio↗
USGS2020

Evaluation of acute and chronic toxicity of nickel and zinc to 2 sensitive freshwater benthic invertebrates using refined testing methods

The US Environmental Protection Agency (USEPA) is reviewing the protectiveness of the national ambient water quality criteria (WQC) for nickel (Ni) and zinc (Zn) and compiling toxicity databases to update the WQC. An amphipod ( Hyalella azteca ) and a unionid mussel ( Lampsilis siliquoidea ) have shown high sensitivity to Ni and Zn in previous studies. However, there remained uncertainties regarding the influence of test duration (48 vs 96 h) and the presence and absence of food in acute exposures with the amphipod, and there were also concerns about poor control of amphipod growth and reproduction and mussel growth in chronic exposures. We conducted acute 48‐ and 96‐h water‐only toxicity tests to evaluate the influence of feeding and test durations on the toxicity of dissolved Ni and Zn to the amphipod; we also used recently refined test methods to conduct chronic Ni and Zn toxicity tests to evaluate the sensitivity of the amphipod (6‐wk exposure) and the mussel (4‐ and 12‐wk exposures). The 96‐h 50% effect concentrations (EC50s) of 916 µg Ni/L and 99 µg Zn/L from acute amphipod tests without feeding decreased from the 48‐h EC50s by 62 and 33%, respectively, whereas the 96‐h EC50s of 2732 µg Ni/L and 194 µg Zn/L from the tests with feeding decreased from the 48‐h EC50s by 10 and 26%, indicating that the presence or absence of food had apparent implications for the 96‐h EC50. Our chronic 6‐wk EC20s for the amphipod (4.5 µg Ni/L and 35 µg Zn/L) were 50 to 67% lower than the 6‐wk EC20s from previous amphipod tests, and our chronic 4‐wk EC20s for the mussel (41 µg Ni/L and 66 µg Zn/L) were similar to or up to 42% lower than the 4‐wk EC20s from previous mussel tests. The lower EC20s from the present study likely reflect more accurate estimates of inherent sensitivity to Ni and Zn due to the refined test conditions. Finally, increasing the chronic test duration from 4 to 12 wk substantially increased the toxicity of Zn to the mussel, whereas the 4‐ and 12‐wk Ni effect needs to be re‐evaluated to understand the large degree of variation in organism responses observed in the present study.

Environmental Toxicology and Chemistry↗
USGS2020

Toxicity of carbon dioxide to freshwater fishes: Implications for aquatic invasive species management

Carbon dioxide (CO 2 ) has been approved by the US Environmental Protection Agency as a new aquatic pesticide to control invasive Asian carps and other aquatic nuisance species in the United States. However, limited CO 2 toxicity data could make it challenging for resource managers to characterize the potential risk to nontarget species during CO 2 applications. The present study quantified the toxicity of CO 2 to 2 native riverine fishes, bluegill ( Lepomis macrochirus ) and fathead minnow ( Pimephales promelas ), using 12‐h continuous flow‐through CO 2 exposure at 5, 15, and 25 °C water temperatures. Resulting survival indicated that bluegill (median lethal concentration [LC50] range 91–140 mg/L CO 2 ) were more sensitive to CO 2 than fathead minnow (LC50 range 235–306 mg/L CO 2 ) across all water temperatures. Bluegill were also more sensitive to CO 2 at 5 °C (LC50 91 mg/L CO 2 , 95% CI 85–96 mg/L CO 2 ) than at 25 °C (LC50 140 mg/L CO 2 , 95% CI 135–146 mg/L CO 2 ). Fathead minnow showed an opposite response and were less sensitive at 5 °C (LC50 306 mg/L CO 2 , 95% CI 286–327 mg/L CO 2 ) relative to 25 °C (LC50 235 mg/L CO 2 , 95% CI 224–246 mg/L CO 2 ). Our results show that CO 2 toxicity can differ by species and water temperature. Data from the present study may inform decisions related to the use of CO 2 as a control tool. Environ Toxicol Chem 2020;39:2247–2255. Published 2020. This article is a U.S. government work and is in the public domain in the USA.

Environmental Toxicology and Chemistry (ET&C)↗
USGS2011

Acute toxicity, histopathology, and coagulopathy in American kestrels (Falco sparverius) following administration of the rodenticie diphacinone

The acute oral toxicity of the anticoagulant rodenticide diphacinone was found to be over 20 times greater in American kestrels (Falco sparverius; median lethal dose 96.8 mg/kg body weight) compared with Northern bobwhite (Colinus virginianus) and mallards (Anas platyrhynchos). Modest evidence of internal bleeding was observed at necropsy, although histological examination of heart, liver, kidney, lung, intestine, and skeletal muscle revealed hemorrhage over a wide range of doses (35.1-675 mg/kg). Residue analysis suggests that the half-life of diphacinone in the liver of kestrels that survived was relatively short, with the majority of the dose cleared within 7 d of exposure. Several precise and sensitive clotting assays (prothrombin time, Russell's viper venom time, thrombin clotting time) were adapted for use in this species, and oral administration of diphacinone at 50 mg/kg increased prothrombin time and Russell?s viper venom time at 48 and 96 h postdose compared with controls. Prolongation of in vitro clotting time reflects impaired coagulation complex activity, and generally corresponded with the onset of overt signs of toxicity and lethality. In view of the toxicity and risk evaluation data derived from American kestrels, the involvement of diphacinone in some raptor mortality events, and the paucity of threshold effects data following short-term dietary exposure for birds of prey, additional feeding trials with captive raptors are warranted to characterize more fully the risk of secondary poisoning.

Environmental Toxicology and Chemistry↗
USGS2020

High frequency of lead exposure in the population of an endangered Australian top predator, the Tasmanian wedge-tailed eagle (Aquila audax fleayi)

Lead poisoning, mainly through incidental ingestion of lead ammunition in carcasses, is a threat to scavenging and predatory bird species worldwide. In Australia, shooting for animal control is widespread, and a range of native scavenging species are susceptible to lead exposure. However, the prevalence of lead exposure in Australia's scavenging and predatory birds is largely unknown. We evaluated the degree to which the Tasmanian wedge‐tailed eagle ( Aquila audax fleayi ), an endangered Australian raptor and facultative scavenger, showed evidence of lead exposure. We detected lead in 100% of femur and liver tissues of 109 eagle carcasses opportunistically collected throughout Tasmania between 1996 and 2018. Concentrations were elevated in 10% of 106 liver (> 6 mg/kg dw) and 4% of 108 femur (> 10 mg/kg dw) samples. We also detected lead in 96% of blood samples taken from 24 live nestlings, with 8% at elevated concentrations (> 10 μg/dL). Of the liver samples with elevated lead, 73% had lead 207/206 isotope ratios within the published range of lead‐based bullets available in Tasmania. These first comprehensive data on lead exposure of an Australian raptor are comparable to those for raptor studies elsewhere that identify lead‐based ammunition exposure as a conservation threat. Our findings highlight the importance of further research and efforts to address lead contamination throughout the Tasmanian ecosystem and in other Australian regions.

Environmental Toxicology and Chemistry↗