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At least 1,423 records · Page 79Linked to original sources
USGS2025

Tree swallows as indicators of per- and polyfluoroalkyl substance exposure and effects at select Department of Defense sites along the East Coast and at sites with different sources in the Upper Midwest, United States

Questions remain about the distribution of per- and polyfluoroalkyl substances (PFAS) in the environment, the sources and movement within and between ecosystems, and whether there are effects from such exposure. Information from the Upper Midwest and the mid-Atlantic regions of the United States, which have different PFAS sources, were investigated. Concentrations of Total 40 (sum of 40 PFAS), perfluorooctane sulfonate, perfluorohexane sulfonate, and Total 13 (sum of 13 PFAS) were consistently higher, by as much as a factor of 40, in tree swallow ( Tachycineta bicolor ) tissue samples (eggs, nestlings, and diet) at sites along the East Coast, where aqueous film-forming foams (AFFF) were extensively used when compared with East Coast reference sites. Sites in the Upper Midwest, with other PFAS sources, had qualitatively lower concentrations of PFAS than AFFF source sites. Perfluorooctane sulfonate was the only PFAS detected in all samples. Concentrations of most other PFAS, such as the carboxylates and fluorotelomers, did not differ between AFFF and reference sites. Perfluorohexane sulfonate, the second-most common constituent of some legacy AFFF formulations, was <1% of Total 40 at the reference sites in eggs and nestlings, but perfluorohexane sulfonate represented up to 9.7% (eggs) and 9.0% (nestlings) at AFFF-influenced sites. Despite differences in PFAS exposure, the daily probability of egg and nestling survival, as well as haptoglobin-like activity (PIT54) and total immunoglobulin Y, was similar across all sites. There were also no significant associations between these end points and concentrations of Total 40 or individual PFAS in eggs or nestlings.

East Coast, Upper Midwest↗
USGS2025

Effects of dietary selenium on the amphipod Hyalella azteca and the midge Chironomus dilutus

Chronic selenium (Se) water quality criteria are based primarily on dietary organoselenium exposure and subsequent reproductive effects in fish. Available chronic Se toxicity data suggests that invertebrates are less sensitive than fish, but chronic invertebrate studies are limited. We evaluated yeast-based diets for chronic toxicity studies with Hyalella azteca and Chironomus dilutus. Growth and survival were similar among C. dilutus fed a yeast-only diet, a mixture of yeast and fish flake food, and a mixture of yeast and diatoms. Survival and growth of H. azteca were best in the yeast + diatom diet, so this diet was used for subsequent tests. In rangefinder tests, H. azteca 28-day survival, growth, and biomass, and C. dilutus 11-day survival were all significantly reduced at a dietary Se concentration of 49 µg/g dry weight, whereas C. dilutus growth and biomass were only affected at 200 µg/g dry weight Se. H. azteca had similar sensitivity to dietary Se in a 28–42-day chronic test—survival, growth, and biomass were significantly reduced at 44.5 µg/g dry weight Se. Dietary selenium reduced H. azteca reproduction by 75%–100% relative to Controls, but differences were not significant. Tissue Se EC10s were lower for H. azteca (9.0–23 µg/g dry weight) than for C. dilutus (11–56 µg/g dry weight). However, model evaluations suggest that the C. dilutus 11-day survival and H. azteca 42-day EC10s were less reliable than other endpoints. When tissue EC10s were converted to equivalent Se concentrations in fish tissue with a food web model, H. azteca (18 µg/g dry weight) and C . dilutus (68 µg/g dry weight) ranked 6th and 12th of 13 freshwater genera, respectively. Overall, these results suggest that the current U.S. Environmental Protection Agency tissue-based Se water quality criteria would be protective for fish and invertebrates and could be used for management of fishless waters.

Environmental Toxicology and Chemistry↗
USGS2025

Predictors of mercury and pesticide fluxes by emerging adult aquatic insects from prairie pothole wetlands

Aquatic and terrestrial food webs are linked by movements of aquatic insects during their development from larvae to adults. Contaminants can affect these linkages by reducing insect survival and increasing tissue contaminant concentrations through adult metamorphosis, thus changing contaminant flux from water to land. Most anthropogenically influenced freshwater ecosystems are exposed to multiple contaminants. To better understand the combined effects of contaminants on aquatic–terrestrial linkages, we investigated how adult aquatic insect emergence and tissue contaminant concentrations affect insect-mediated contaminant flux of mercury and pesticides from wetlands. In a field survey of 15 wetlands in the Prairie Pothole Region, an important agricultural region of North America, we found that insect-mediated mercury flux was 3.5 times more strongly predicted by emergence biomass than tissue mercury concentration. Thus, factors that were previously found to influence aquatic insect emergence biomass in this system—including insecticide tissue concentrations in adult insects, open water surface area, and agricultural land use—were the most likely to drive insect-mediated mercury flux. Pesticide flux, however, was 3.3 times more strongly predicted by the tissue pesticide concentration than by emergence. Thus, factors that influence pesticide exposure and, to a smaller extent, emergence biomass were the most likely to drive pesticide flux. Our results show how factors driving contaminant fluxes by adult aquatic insects differ by contaminant class, and they suggest one mechanism by which toxic effects of one contaminant (pesticides) could influence the flux of another (mercury). Predicting contaminant fluxes in areas where different mixtures of contaminants are present can aid in identifying risk to insectivores.

Prairie Pothole Region↗
USGS2026

Accumulation of per- and polyfluoroalkyl substances (PFAS) and their association with immune parameters in nestling ospreys (Pandion haliaetus) from Chesapeake and Delaware Bays, USA

Per- and polyfluoroalkyl substances (PFAS) are a class of widespread, environmentally persistent compounds that pose a potential threat to wildlife and human health. Despite recent efforts to reduce the use of long-chain PFAS in industrial practices and commercial/consumer products, the persistence and solubility of PFAS have led to their detection in wildlife on a global scale. Osprey ( Pandion haliaetus ) have long been used as a sentinel species with an extensive history of serving as an effective bioindicator of contamination. Here we report on a large-scale evaluation of PFAS and potential health effects in osprey from the Chesapeake and Delaware Bays, USA. In 2011 and 2015, we collected plasma samples from osprey nestlings throughout the Chesapeake and Delaware Bay watersheds. We quantified 40 PFAS congeners in osprey plasma via liquid chromatography-mass spectrometry and analyzed plasma for indicators of immune and thyroid function, and plasma biochemistry. In all birds, perfluorooctanesulfonic acid (PFOS) was the most commonly detected PFAS, followed by perfluoroundecanoic acid, (PFUnA) and perfluorodecanoic acid (PFDA). In nestling plasma from Chesapeake Bay, PFOS tended to be a higher average contributor to PFAS profiles compared to samples from Delaware Bay. In contrast, long-chain perfluoroalkyl carboxylic acids (PFCAs) such as PFUnA and PFDA comprised larger percentages of total PFAS in osprey plasma from Delaware Bay relative to Chesapeake Bay. While some PFAS concentrations were associated with plasma health indicators, the proportion of variation explained was low. Overall, our study provides a more thorough understanding of PFAS presence in the Chesapeake and Delaware Bays and is one of the first to examine whether PFAS exposure is associated with adverse health effects in wildlife.

Chesapeake and Delaware Bays↗
USGS2026

Using organic compounds and salt mixtures to investigate potential mechanisms of major ion toxicity to the mayfly Neocloeon triangulifer

Field assessments and laboratory studies have demonstrated that mayflies (Ephemeroptera) are relatively sensitive to increased concentrations of major geochemical ions (Na + , Ca 2+ , Mg 2+ , K + , Cl − , SO 4 2− , HCO 3 − /CO 3 2- ), but much remains to be learned about potential mechanisms of toxicity. In the present study, we sought to determine whether solution osmolarity is sufficient to predict the toxic effects of major ions to a mayfly, Neocloeon triangulifer . We further investigated whether binary mixtures of major ion salts with common cations or common anions provide evidence of concentration addition or independent action, potentially illuminating toxicity drivers for this species. Finally, we sought to determine if there are mechanisms for major ion toxicity to mayflies that are comparable to those for other species. The toxicity of single salts showed a Ca-dependent correlation with the total component concentration (the sum of individual ion concentrations, a close correlate of osmolarity), but the effect concentrations were well below those causing toxicity from mannitol (presumed to have only an osmotic effect), suggesting that a general osmotic effect is not responsible for major ion toxicity in this species. The mixture experiments consistently indicated additive toxicity and consistency with the relationship to total component concentration, which supports a single toxic mechanism and thus no evidence for ion-specific mechanisms, as reported for other species. Given the lack of evidence of ion-specific toxicity, the total component metric is likely useful for a broad range of ionic compositions.

Environmental Toxicology and Chemistry↗
USGS1994

A toxic equivalency factor scale for polychlorinated dibenzofurans

The ethoxyresorufin O -deethylase (EROD) induction of 20 polychiorinated dibenzofurans (PCDFs) was examined in the H4IIE rat hepatoma cell bioassay. The selection of the compounds tested was based on a multivariate chemical characterization laying the groundwork for covering the whole chemical series of PCDFs. The EROD induction potency was found to vary in ED50 values from 25 to 100,000,000 pg/mg, i.e., nearly seven orders of magnitude. The response of the bioassay was calibrated against the 2,3,7,8-tetrachlorodibenzo- p -dioxin, enabling the corresponding toxic equivalency factors (TEFs) to be calculated. In order to establish a quantitative structure-activity relationship (QSAR) for the TEF values, 37 physicochemical descriptor variables were used to chemically characterize the 87 tetra- to octachlorinated PCDFs. Using partial least-squares modeling on a training set of 10 congeners, a QSAR model with sound predictive power was obtained. The QSAR model was validated with a validation set of additional 10 congeners. The predicted TEFs indicate that a large number of congeners are potent EROD inducers.

Toxicological Sciences↗
USGS2005

Exposure to polybrominated diphenyl ethers (PBDEs): Changes in thyroid, vitamin A, glutathione homeostasis, and oxidative stress in American kestrels (Falco sparverius)

Polybrominated diphenyl ethers (PBDEs), a class of additive flame retardants, are temporally increasing in wildlife tissues and capable of disrupting normal endocrine function. We determined whether in ovo and post-hatch exposure of captive American kestrels ( Falco sparverius ) to environmentally relevant PBDEs alter thyroid, retinol, and oxidative stress measures. Control eggs were injected with safflower oil and subsequent nestlings fed the same vehicle; dosed eggs received PBDE congeners (BDE-47, -99, -100, -153), which mainly comprise the Penta-BDE commercial mixture, dissolved in safflower oil at concentrations (1500 ng/g total [Σ] PBDEs) approximating those in Great Lakes gull eggs. Nestlings hatching from dosed eggs were orally exposed for 29 days to variable ΣPBDE concentrations that are similar to levels reported in tissues of Great Lakes trout (100 ng/g). Treatment kestrels had lower plasma thyroxine (T 4 ), plasma retinol, and hepatic retinol and retinyl palmitate concentrations, but unaltered triiodothyronine (T 3 ) concentrations and thyroid glandular structure. BDE-47, -100, and -99 were negatively associated with plasma T 4 , plasma retinol (BDE-100, -99) and hepatic retinol (BDE-47). Despite an antioxidant-rich diet, PBDE exposure induced hepatic oxidative stress, particularly in females, with an increased hepatic GSSG:GSH ratio, a marginal increase in lipid peroxidation, and increased oxidized glutathione. Positive associations were found between concentrations of BDE-183 and thiols and, in males, between BDE-99 and reduced GSH, but a negative association occurred between BDE-99 and TBARS. Subsequently, concentrations of PBDE congeners in wild birds may alter thyroid hormone and vitamin A concentrations, glutathione metabolism and oxidative stress.

Toxicological Sciences↗
USGS2006

Fasting augments PCB impact on liver metabolism in anadromous Arctic Char

Anadromous arctic char (Salvelinus alpinus) undertake short feeding migrations to seawater every summer and accumulate lipids, while the rest of the year is spent in fresh water where the accumulated lipid reserves are mobilized. We tested the hypothesis that winter fasting and the associated polychlorinated biphenyls' (PCBs) redistribution from lipid depots to critical tissues impair the liver metabolic capacity in these animals. Char were administered Aroclor 1254 (0, 1, 10, and 100 mg/ kg body mass) orally and maintained for 4 months without feeding to mimic seasonal winter fasting, while fed groups (0 and 100 mg Aroclor 1254/kg) were maintained for comparison. A clear dose-related increase in PCB accumulation and cytochrome P4501A (CYP1A) protein content was observed in the livers of fasted fish. This PCB concentration and CYP1A response with the high dose of Aroclor were 1.5-fold and 3-fold greater in the fasted than in the fed fish, respectively. In fed fish, PCB exposure lowered liver glycogen content, whereas none of the other metabolic indicators were significantly affected. In fasted fish, PCB exposure depressed liver glycogen content and activities of glucose-6-phosphate dehydrogenase, alanine aminotransferase, lactate dehydrogenase, and phosphoenolpyruvate carboxykinase and elevated 3-hydroxyacylcoA dehydrogenase activity and glucocorticoid receptor protein expression. There were no significant impacts of PCB on heat shock protein 70 (hsp70) and hsp90 contents in either fed or fasted fish. Collectively, our study demonstrates that winter emaciation associated with the anadromous lifestyle predisposes arctic char to PCB impact on hepatic metabolism including disruption of the adaptive metabolic responses to extended fasting. ?? 2006 Oxford University Press.

Toxicological Sciences↗
USGS2006

The colloidal thyroxine (T4) ring as a novel biomarker of perchlorate exposure in the African clawed frog Xenopus laevis

The purpose of this study was to determine if changes in colloidal thyroxine (T4) immunoreactivity can be used as a biomarker of perchlorate exposure in amphibian thyroid tissue. Larval African clawed frogs (Xenopus laevis) were exposed to 0, 1, 8, 93, and 1131 ??g perchlorate/l for 38 and 69 days to cover the normal period of larval development and metamorphosis. The results of this study confirmed the presence of an immunoreactive colloidal T4 ring in thyroid follicles of X. laevis and demonstrated that the intensity of this ring is reduced in a concentration-dependent manner by perchlorate exposure. The smallest effective concentration of perchlorate capable of significantly reducing colloidal T4 ring intensity was 8 ??g perchlorate/l. The intensity of the immunoreactive colloidal T4 ring is a more sensitive biomarker of perchlorate exposure than changes in hind limb length, forelimb emergence, tail resorption, thyrocyte hypertrophy, or colloid depletion. We conclude that the colloidal T4 ring can be used as a sensitive biomarker of perchlorate-induced thyroid disruption in amphibians. ?? Copyright 2006 Oxford University Press.

Toxicological Sciences↗
USGS2008

Exposure of xenopus laevis tadpoles to cadmium reveals concentration-dependent bimodal effects on growth and monotonic effects on development and thyroid gland activity

Xenopus laevis were exposed to 0-855 ??g cadmium (Cd)/l (measured concentrations) in FETAX medium from fertilization to 47 days postfertilization. Measurements included embryonic survival and, at 47 days, tadpole survival, snout-vent length, tail length, total length, hindlimb length, weight, Nieuwkoop-Faber (NF) stage of development, initiation of metamorphic climax (??? NF 58), and thyroid follicle cell height. Embryonic and larval survival were unaffected by Cd. Relative to control tadpoles, reduced tail and total length were observed at 0.1- 8 and at 855 ??g Cd/l; and reduced snout-vent length, hindlimb length, and weight were observed at 0.1-1 and at 855 ??g Cd/l. Mean stage of development and rate of initiation of climax were unaffected by Cd at 0-84 ??g/l; however, none of the tadpoles exposed to 855 ??g Cd/l progressed beyond mid-premetamorphosis (NF 51). Thyroid glands with fully formed follicles were observed in all tadpoles ??? NF 49 examined. Follicle cell height was unaffected by Cd at 0-84 ??g/l but it was reduced at 855 ??g/l; in the latter, cell height was reduced even when compared with NF 49-51 tadpoles pooled from the 0 to 84 ??g Cd/l groups. In conclusion, (1) Cd affected tadpole growth in a bimodal pattern with the first and second inhibitory modes at concentrations below and above 84 ??g Cd/l, respectively; (2) exposure to high Cd concentrations (855 ??g/l) reduced thyroid activity and arrested tadpole development at mid-premetamorphosis; and (3) unlike its effect on growth, Cd inhibited tadpole development and thyroid function in a seemingly monotonic pattern.

Toxicological Sciences↗
USGS2017

Effects on circulating steroid hormones and gene expression along the hypothalamus–pituitary–gonadal axis in adult Japanese quail exposed to 17β-trenbolone across multiple generations

We investigated the effects of the androgenic growth promoter 17β-trenbolone (17βTB) on adult Japanese quail ( Coturnix japonica ) exposed across three generations. The F0 generation was exposed after sexual maturity to 0, 1, 5, 10, 20, and 40 ppm through feed. The F1 generation was exposed in ovo by maternal transfer and through feed at the same doses as their parents. The F2 generation was exposed in ovo only. Levels of plasma sex steroids, gonadal Cytochrome P450 aromatase (CYP19A1) mRNA and select brain neuroendocrine peptide mRNAs were measured. In males, testosterone levels did not differ in any generation from those in controls. Estradiol was significantly elevated in 17βTB treated F0 and F1 males. In F0 and F1 females, testosterone was suppressed by 17βTB, whereas estradiol was significantly higher at 40 ppm in F0 and at 10 ppm in F1 females. CYP19A1 expression in F1 males and females increased suggesting a compensatory response to the androgenic effects of 17βTB. Few significant effects were observed in the F2 birds indicating that in ovo exposure had limited effects on the monitored endpoints. Overall, our results confirmed endocrine disrupting effects of dietary 17βTB in Japanese quail but the response was dependent on sex, developmental stage at initiation of exposure, and dose.

Toxicological Sciences↗
USGS2012

Safety of florfenicol administered in feed to tilapia (Oreochromis sp.)

The safety of Aquaflor&reg; (50% w/w florfenicol [FFC]) incorporated in feed then administered to tilapia for 20 days (2x the recommended duration) at 0, 15, 45, or 75 mg/kg body weight/day (0, 1, 3, or 5x the recommended dose of 15 mg FFC/kg BW/d) was investigated. Mortality, behavioral change, feed consumption, body size, and gross and microscopic lesions were determined. Estimated delivered doses were >96.9% of target. Three unscheduled mortalities occurred but were considered incidental since FFC-related findings were not identified. Feed consumption was only affected during the last 10 dosing days when the 45 and 75 mg/kg groups consumed only 62.5% and 55.3% of the feed offered, respectively. There were significant, dose-dependent reductions in body size in the FFC-dose groups relative to the controls. Treatment-related histopathological findings included increased severity of lamellar epithelial hyperplasia, increased incidence of lamellar adhesions, decreased incidence of lamellar telangiectasis in the gills, increased glycogen-type and lipid-type hepatocellular vacuolation in the liver, decreased lymphocytes, increased blast cells, and increased individual cell necrosis in the anterior kidney, and tubular epithelial degeneration and mineralization in the posterior kidney. These changes are likely to be of minimal clinical relevance, given the lack of mortality or morbidity observed. This study has shown that FFC, when administered in feed to tilapia at the recommended dose (15 mg FFC/kg BW/day) for 10 days would be well tolerated.

Toxicologic Pathology↗
USGS2014

Nonlesions, misdiagnoses, missed diagnoses, and other interpretive challenges in fish histopathology studies: a guide for investigators, authors, reviewers, and readers

Differentiating salient histopathologic changes from normal anatomic features or tissue artifacts can be decidedly challenging, especially for the novice fish pathologist. As a consequence, findings of questionable accuracy may be reported inadvertently, and the potential negative impacts of publishing inaccurate histopathologic interpretations are not always fully appreciated. The objectives of this article are to illustrate a number of specific morphologic findings in commonly examined fish tissues (e.g., gills, liver, kidney, and gonads) that are frequently either misdiagnosed or underdiagnosed, and to address related issues involving the interpretation of histopathologic data. To enhance the utility of this article as a guide, photomicrographs of normal and abnormal specimens are presented. General recommendations for generating and publishing results from histopathology studies are additionally provided. It is hoped that the furnished information will be a useful resource for manuscript generation, by helping authors, reviewers, and readers to critically assess fish histopathologic data.

Toxicologic Pathology↗
USGS1999

Factors influencing estimation of pesticide-related wildlife mortality

Free-ranging wildlife is regularly exposed to pesticides and can serve as a sentinel for human and environmental health. Therefore a comprehensive pesticide hazard assessment must incorporate the effects of actual applications on free-ranging wildlife. Mortality is the most readily reported wildlife effect, and the significance of these data can be realized only when placed in context with the factors that affect the gathering of this type of information. This paper reviews the variables that affect the collection of wildlife mortality data. Data show that most effects on wildlife are not observed, and much of observed mortality is not reported. Delays in reporting or in the response to a report and exposure to multiple stressors distort the exposure-effect relationship and can result in uncertainty in determining the cause of death. The synthesis of information strongly indicates that the actual number of affected animals exceeds the number recovered.

Toxicology and Industrial Health↗
USGS2016

Combined exposure of diesel exhaust particles and respirable Soufrière Hills volcanic ash causes a (pro-)inflammatory response in an in vitro multicellular epithelial tissue barrier model

Background There are justifiable health concerns regarding the potential adverse effects associated with human exposure to volcanic ash (VA) particles, especially when considering communities living in urban areas already exposed to heightened air pollution. The aim of this study was, therefore, to gain an imperative, first understanding of the biological impacts of respirable VA when exposed concomitantly with diesel particles. Methods A sophisticated in vitro 3D triple cell co-culture model of the human alveolar epithelial tissue barrier was exposed to either a single or repeated dose of dry respirable VA (deposited dose of 0.26 ± 0.09 or 0.89 ± 0.29 μg/cm 2 , respectively) from Soufrière Hills volcano, Montserrat for a period of 24 h at the air-liquid interface (ALI). Subsequently, co-cultures were exposed to co-exposures of single or repeated VA and diesel exhaust particles (DEP; NIST SRM 2975; 0.02 mg/mL), a model urban pollutant, at the pseudo-ALI. The biological impact of each individual particle type was also analysed under these precise scenarios. The cytotoxic (LDH release), oxidative stress (depletion of intracellular GSH) and (pro-)inflammatory (TNF-α, IL-8 and IL-1β) responses were assessed after the particulate exposures. The impact of VA exposure upon cell morphology, as well as its interaction with the multicellular model, was visualised via confocal laser scanning microscopy (LSM) and scanning electron microscopy (SEM), respectively. Results The combination of respirable VA and DEP, in all scenarios, incited an heightened release of TNF-α and IL-8 as well as significant increases in IL-1β, when applied at sub-lethal doses to the co-culture compared to VA exposure alone. Notably, the augmented (pro-)inflammatory responses observed were not mediated by oxidative stress. LSM supported the quantitative assessment of cytotoxicity, with no changes in cell morphology within the barrier model evident. A direct interaction of the VA with all three cell types of the multicellular system was observed by SEM. Conclusions Combined exposure of respirable Soufrière Hills VA with DEP causes a (pro-)inflammatory effect in an advanced in vitro multicellular model of the epithelial airway barrier. This finding suggests that the combined exposure to volcanic and urban particulate matter should be further investigated in order to deduce the potential human health hazard, especially how it may influence the respiratory function of susceptible individuals (i.e. with pre-existing lung diseases) in the population.

Particle and Fibre Toxicology↗
USGS1996

Use of behavioral avoidance testing in natural resource damage assessment

Natural Resource Damage Assessment (NRDA) provisions established under federal and state statutes enable natural resource trustees to recover compensation from responsible parties to restore injured natural resources. Behavioral avoidance testing with fish has been used in NRDAs to determine injuries to natural resources and to establish restoration thresholds. In this manuscript we evaluate the use of avoidance testing to NRDA. Specifically, we discuss potential “acceptance criteria” to evaluate the applicability and relevance of avoidance testing. These acceptance criteria include: (1) regulatory relevance, (2) reproducibility of testing, (3) ecological significance, (4) quality assurance/quality control, and (5) relevance to restoration. We discuss each of these criteria with respect to avoidance testing. Overall, we conclude that avoidance testing can be an appropriate, defensible, and desirable aspect of an NRDA.

ASTM Symposium on Environmental Toxicology and Ris↗