bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response of larval Xenopus laevis to atrazine: Assessment of growth, metamorphosis, and gonadal and laryngeal morphology
Authors: Carr James A. , Gentles Angie , Smith Ernest E. , Goleman Wanda L. , Urquidi Lina J. , Thuett Kerry , Kendall Ronald J. , Giesy John P. , Gross Tim S. , Solomon Keith R. , Van Der Kraak Glen 
Published: March 2010

Abstract
Larval Xenopus laevis were exposed to one of four concentrations of atrazine (0, 1, 10, or 25 μg/L, 11 replicate tanks per treatment, 60–65 larvae per replicate) dissolved in an artificial pond water (frog embryo teratogenesis assay-Xenopus [FETAX]) medium beginning 48 h after hatching until the completion of metamorphosis. Separate groups of larvae (six replicate tanks per treatment, 60–65 larvae per replicate) were exposed to estradiol (100 μg/L), dihydrotestosterone (100 μg/L), or ethanol vehicle control dissolved in FETAX medium. None of the treatments affected posthatch mortality, larval growth, or metamorphosis. There were no treatment effects on sex ratios except for estradiol, which produced a greater percentage of female offspring. Exposure to either estradiol or 25 μg atrazine/L increased the incidence of intersex animals based on assessment of gonadal morphology. Atrazine did not reduce the size of the laryngeal dilator muscle, a sexually dimorphic muscle in this species. We conclude that environmentally relevant concentrations of atrazine do not influence metamorphosis or sex ratios and do not inhibit sexually dimorphic larynx growth in X. laevis. The incidence of atrazine-induced intersex animals was small (&lt;5%) and occurred only at the greatest concentration of atrazine tested, a concentration that is rarely observed in surface waters in the United States.
Occurrence of several arsenic compounds in the liver of birds, cetaceans, pinnipeds, and sea turtles
Authors: Kubota Reiji , Kunito Takashi , Tanabe Shinsuke 
Published: March 2010

Abstract
Concentrations of total arsenic and individual arsenic compounds were determined in livers of birds, cetaceans, pinnipeds, and sea turtles by using hydride generation-atomic absorption spectrometry and high-performance liquid chromatography/inductively coupled plasma-mass spectrometry. Hepatic arsenic concentrations in loggerhead turtles (11.2 ± 3.0 μg/g dry wt) and black-footed albatrosses (12.2 ± 10.8 μg/g dry wt) were extremely high among the species examined, and the values were comparable with those of lower trophic marine animals such as fishes, cephalopods, crustaceans, and shellfishes. In all the species, arsenobetaine was the predominant arsenic compound in the livers. Especially, for black-footed albatrosses and black-tailed gull, the mean percentage of arsenobetaine was as high as 97.1 and 87.5, respectively, of extractable arsenic. The present study is among the first on arsenic speciation in avian species. Total arsenic concentration was strongly correlated with the concentration of arsenobetaine, while no significant relationship was observed between total arsenic concentration and other arsenic compounds in these animals. Because arsenobetaine is known to be rapidly excreted into the urine in humans and experimental animals, the observed results suggest that higher trophic marine animals might have a unique metabolism of arsenobetaine and that arsenobetaine plays an important role in the accumulation of arsenic in these animals.
Testosterone metabolism in the estuarine mysid Neomysis integer (Crustacea; Mysidacea) following tributyltin exposure
Authors: Verslycke Tim , Poelmans Sofie , De Wasch Katia , Vercauteren Jordy , Devos Christophe , Moens Luc , Sandra Patrick , De Brabander Hubert F. , Janssen Colin R. 
Published: March 2010

Abstract
Current evidence suggests that the biocide tributyltin (TBT) causes the development of imposex, a state of pseudoher-maphrodism in which females exhibit functional secondary male characteristics, by altering the biotransformation or elimination of testosterone. Imposex in gastropods following TBT exposure is the most complete example of the effects of an endocrine disrupter on marine invertebrates. Previous studies have demonstrated that the estuarine mysid Neomysis integer converts testosterone into multiple polar and nonpolar metabolites resulting from both phase I and phase II biotransformations. In this study, the effects of TBT chloride (TBTCl) on the phase I and II testosterone metabolism of N. integer were evaluated. The TBTCl was highly toxic to N. integer (96-h median lethal concentration [LC50] of 164 ng/L). To assess the effects on testosterone metabolism, mysids were exposed for 96 h to different concentrations of TBTCl (control, 10, 100, and 1,000 ng/L), and testosterone elimination as polar hydroxylated, nonpolar oxido-reduced, and glucose- and sulfate-conjugated metabolites was examined. The TBTCl differentially affected testosterone metabolism. The effect of TBTCl on phase I metabolism was unclear and has been shown to vary among species, likely depending on the inducibility or presence of certain P450 isozyme families. Reductase activity and metabolic androgenization were induced in the 10-ng/L treatment, whereas higher concentrations resulted in a reduction of sulfate conjugation. The exact mechanisms underlying TBT-induced imposex and alterations in the steroid metabolism need to be further elucidated.
Differential effects of copper and cadmium exposure on toxicity endpoints and gene expression in Chlamydomonas reinhardtii
Authors: Stoiber Tasha L. , Shafer Martin M. , Armstrong David E. 
Published: March 2010

Abstract
The toxicity of cadmium to aquatic organisms is well known, but the mechanisms of toxicity are not as clearly understood. In the present study, Cd bioassay experiments incorporating both traditional endpoints and novel thiol-based endpoints were conducted with Chlamydomonas reinhardtii. The results were compared with results from previous bioassay experiments to probe the apparent contrasting biochemical mechanisms of toxicity of copper and cadmium as expressed in cellular glutathione and the glutathione cycle. Total glutathione and reduced to oxidized glutathione ratio (GSH/GSSG) measurements were remarkably different in Cd- compared with Cu-exposed cells. Whereas total glutathione in cells decreased with increasing Cu concentration, Cd caused dramatic increases. Total glutathione increased by 4.5-fold with 80 nM Cd treatment over concentrations in Cd-free controls. Glutathione reductase (GR) enzyme activity was positively correlated (r2Cu = 0.96, r2Cd = 0.85) with glutathione concentrations for both metals. Measurements of mRNA for GR were increased 2-fold in response to Cd exposure (80 nM) and correlated well with GR enzyme activity. Glutathione concentrations and GR enzyme activity are useful endpoints for both Cu and Cd toxicity in algae, even though the metals elicit opposing responses. We conclude that Cu decreases glutathione concentrations by inhibiting GR enzyme activity. In contrast, Cd stimulates GR enzyme activity and increases glutathione concentrations as cells respond to Cd-induced stress by producing increased antioxidant capacity. The present study demonstrates that determining the glutathione response in cells is important for understanding the metal-specific mechanisms of toxicity and that these associated novel endpoints may be useful metrics for accurately predicting toxicity. Environ. Toxicol. Chem. 2010;29:191–200. © 2009 SETAC
Selenium distribution in a lake system receiving effluent from a metal mining and milling operation in Northern Saskatchewan, Canada
Authors: Wiramanaden Cheryl I. E. , Forster Erin K. , Liber Karsten 
Published: March 2010

AbstractThe release of selenium (Se) at relatively low concentrations into aquatic ecosystems over time can result in the accumulation and, if thresholds are exceeded, subsequent adverse effects in sensitive species, including higher trophic levels (such as fish). A milling operation in Northern Saskatchewan, Canada, releases treated effluent into a small stream system, and Se has accumulated in sediments and aquatic biota over time. The present study evaluated four small lakes downstream of the effluent discharge point, and one lake upstream, in order to describe and understand the distribution of Se in abiotic environmental compartments and the transfer of Se into benthic macroinvertebrates. The concentrations of Se in sampled sediments were highly variable but exceeded proposed thresholds for the protection of fish and aquatic birds in all study lakes downstream of the effluent discharge point. Selenium concentrations in surface water, whole-sediment, and sediment pore water revealed that whole-body Se concentrations in benthic invertebrates (chironomids) are best correlated with Se in pore water. It is proposed that Se accumulates in sediments through an association with the total organic carbon content of sediment and that Se is fixed from the surface water by micro-organisms and primary producers. The relationship between Se in pore water and Se in whole sediments appears to be influenced by the organic carbon content of each medium, and Se bioavailability in sediment and transfer to higher trophic levels via benthic macroinvertebrates is likely speciation dependent. Environ. Toxicol. Chem. 2010;29:606–616. © 2009 SETAC
Enhanced reproduction in mallards fed a low level of methylmercury: An apparent case of hormesis
Authors: Heinz Gary H. , Hoffman David J. , Klimstra Jon D. , Stebbins Katherine R. 
Published: March 2010

Abstract
Breeding pairs of mallards (Anas platyrhynchos) were fed a control diet or a diet containing 0.5 µg/g mercury (Hg) in the form of methylmercury chloride. There were no effects of Hg on adult weights and no overt signs of Hg poisoning in adults. The Hg-containing diet had no effect on fertility of eggs, but hatching success of eggs was significantly higher for females fed 0.5 µg/g Hg (71.8%) than for controls (57.5%). Survival of ducklings through 6 d of age was the same (97.8%) for controls and mallards fed 0.5 µg/g mercury. However, the mean number of ducklings produced per female was significantly higher for the pairs fed 0.5 µg/g Hg (21.4) than for controls (16.8). Although mercury in the parents' diet had no effect on mean duckling weights at hatching, ducklings from parents fed 0.5 µg/g Hg weighed significantly more (mean = 87.2 g) at 6 d of age than did control ducklings (81.0 g). The mean concentration of Hg in eggs laid by parents fed 0.5 µg/g mercury was 0.81 µg/g on a wet-weight basis. At this time, one cannot rule out the possibility that low concentrations of Hg in eggs may be beneficial, and this possibility should be considered when setting regulatory thresholds for methylmercury. Environ. Toxicol. Chem. 2010;29:650–653. © 2009 SETAC
Triclocarban, triclosan, polybrominated diphenyl ethers, and 4-nonylphenol in biosolids and in soil receiving 33-year biosolids application
Authors: Xia Kang , Hundal Lakhwinder S. , Kumar Kuldip , Armbrust Kevin , Cox Albert E. , Granato Thomas C. 
Published: March 2010

Abstract
Land application of biosolids is a common practice throughout the world. However, concerns continue to be raised about the safety of this practice, because biosolids may contain trace levels of organic contaminants. The present study evaluated the levels of triclocarban (TCC), triclosan (TCS), 4-nonylphenol (4-NP), and polybrominated diphenyl ethers (PBDEs) in biosolids from 16 wastewater treatment plants and in soils from field plots receiving annual applications of biosolids for 33 years. All of the four contaminants evaluated were detected in most of the biosolids at concentrations ranging from hundreds of µg/kg to over 1,000 mg/kg (dry wt basis). They were detected at µg/kg levels in the biosolids-amended soil, but their concentrations decreased sharply with increasing soil depth for 4-NP, PBDEs, and TCC, indicating limited soil leaching of those compounds. However, potential leaching of TCS in the biosolids-amended soils was observed. The levels of all four compounds in the surface soil increased with increasing biosolids application rate. Compared with the estimated 33-year cumulative input to the soil during the 33-year consecutive biosolids application, most of the PBDEs and a small percentage of 4-NP, TCC, and TCS remained in the top 120-cm soil layer. These observations suggest slow degradation of PBDEs but rapid transformation of 4-NP, TCC, and TCS in the biosolids-amended soils. Environ. Toxicol. Chem. 2010;29:597–605. © 2009 SETAC
Physiological and potential genetic toxicity of chlortetracycline as an emerging pollutant in wheat (Triticum aestivum L.)
Authors: Xie Xiujie , Zhou Qixing , He Zhangchun , Bao Yanyu 
Published: March 2010

Abstract
Increasing attention is now being paid to antibiotic contamination as a serious environmental issue. Chlortetracycline has been widely used for decades as a human and veterinary medicine, which has resulted in environmental residues and damage to living organisms. In the present study, the physiological and potential genetic toxicity of chlortetracycline was investigated using a wheat (Triticum aestivum L.) bioassay at a concentration range of 0.0625 to 300 mg/L and an exposure time of 24, 48, and 72 h. The results indicated that chlortetracycline at the lower concentrations stimulated germination and cell mitotic division and growth, whereas higher concentrations significantly inhibited processes such as bud length (50–300 mg/L), percentage germination (25–300 mg/L), root length (25–300 mg/L), and mitotic index (MI) (25–300 mg/L). The lowest concentration of chlortetracycline slightly augmented the frequency of micronucleus (MN), chomosomal aberration (CA), and sister chomatid exchange (SCE) in the root tips; however, significant (p &lt; 0.05 and 0.01) levels of augmentation were observed at higher concentrations in a concentration-dependent manner, including the frequencies of MN (25–200 mg/L), CA (10–200 mg/L), and SCE (5–200 mg/L), respectively. The inducement of MN, CA, and SCE decreased at 250 and 300 mg/L as a result of acute cell toxicity. In addition, all endpoints showed a time-dependent increase at 0.0625 to 200 mg/L. These results imply that chlortetracycline (≥5 mg/L) may be genotoxic to plant cells, and exposure to chlortetracycline may pose a potential genotoxic risk to living organisms. Comparatively, SCE was the most sensitive, followed by CA, and MN was the least sensitive to chlortetracycline genotoxicity in wheat. The results also suggest that the wheat bioassay is efficient, simple, and reproducible for monitoring the genotoxicity of chlortetracycline in the environment. Environ. Toxicol. Chem. 2010;29:922–928. © 2009 SETAC
Kinetic bacterial bioluminescence assay for contact sediment toxicity testing: Relationships with the matrix composition and contamination
Authors: Bláha Ludek , Hilscherová Klara , Čáp Tomáš , Klánová Jana , Machát Jiří , Zeman Josef , Holoubek Ivan 
Published: March 2010

Abstract
The present study represents the first broader evaluation of the rapid 30-s kinetic bioluminescence assay with Vibrio fisheri (microplate format modification) for contact toxicity testing of whole sediments. The present study focused on river sediments from the Morava River basin, Czech Republic, repeatedly sampled during 2005 to 2006 and analyzed for geological and geochemical parameters, content of toxic metals, major organic pollutants, and toxicity. High natural variation in toxicity (50% inhibitory concentration [IC50] values ranging from 0.8 to &gt;80 mg sediment dry wt/ml) was found (among different sampling periods and years, among sites), and this could be related to the sediment dynamics affected by spring high flows and summer droughts. From the 46 sediment descriptors, exchangeable protons (H+) was the only parameter that consistently correlated with toxicity. Three other descriptors (i.e., content of organic carbon plus two parameters from the detailed silicate analysis of sediments: percentage of SO3 representing total sulfur content, structural water H2O+) also significantly correlated with toxicity. There were only minor and variable correlations with contamination. We propose sediment safety guideline categories for the V. fisheri kinetic test with severe toxicity threshold of IC50 &lt; 1 mg dry wt/ml. Although sediments are considered a rather stable matrix in comparison with river water, we confirmed high variability and dynamics that should be reflected in monitoring plans and field studies. Environ. Toxicol. Chem. 2010;29:507–514. © 2009 SETAC
Seasonally and regionally determined indication potential of bioassays in contaminated river sediments
Authors: Hilscherová Klára , Dušek Ladislav , Šídlová Tereza , Jálová Veronika , Čupr Pavel , Giesy John P. , Nehyba Slavomír , Jarkovský Jiří , Klánová Jana , Holoubek Ivan 
Published: March 2010

Abstract
River sediments are a dynamic system, especially in areas where floods occur frequently. In the present study, an integrative approach is used to investigate the seasonal and spatial dynamics of contamination of sediments from a regularly flooded industrial area in the Czech Republic, which presents a suitable model ecosystem for pollutant distribution research at a regional level. Surface sediments were sampled repeatedly to represent two different hydrological situations: spring (after the peak of high flow) and autumn (after longer period of low flow). Samples were characterized for abiotic parameters and concentrations of priority organic pollutants. Toxicity was assessed by Microtox test; genotoxicity by SOS-chromotest and green fluorescent protein (GFP)-yeast test; and the presence of compounds with specific mode of action by in vitro bioassays for dioxin-like activity, anti-/androgenicity, and anti-/estrogenicity. Distribution of organic contaminants varied among regions and seasonally. Although the results of Microtox and genotoxicity tests were relatively inconclusive, all other specific bioassays led to statistically significant regional and seasonal differences in profiles and allowed clear separation of upstream and downstream regions. The outcomes of these bioassays indicated an association with concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) as master variables. There were significant interrelations among dioxin-like activity, antiandrogenicity and content of organic carbon, clay, and concentration of PAHs and PCBs, which documents the significance of abiotic factors in accumulation of pollutants. The study demonstrates the strength of the specific bioassays in indicating the changes in contamination and emphasizes the crucial role of a well-designed sampling plan, in which both spatial and temporal dynamics should be taken into account, for the correct interpretations of information in risk assessments. Environ. Toxicol. Chem. 2010;29:522–534. © 2009 SETAC
Assessment of contamination of the Svitava and Svratka rivers in the Czech Republic using selected biochemical markers
Authors: Blahová Jana , Havelková Marcela , Kružíková Kamila , Hilscherová Klára , Halouzka Roman , Modrá Helena , Grabic Roman , Halířová Jarmila , Jurčíková Jana , Ocelka Tomáš , Haruštiaková Danka , Svobodová Zdeňka 
Published: March 2010

Abstract
The aim of the present study is to assess aquatic ecosystem contamination using selected biochemical markers: cytochrome P450, ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), tripeptide glutathione, vitellogenin, and 11-ketotestosterone in chub (Leuciscus cephalus L.). Seven locations on the Svitava and Svratka rivers (in the Brno conurbation, Czech Republic) were assessed. The results were compared with the levels of the most important inductors of these biomarkers: organic pollutants hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), DDT and its metabolites, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons in bottom sediment, fish muscle, and semipermeable membrane devices (SPMDs) and metals in sediment. The highest levels of pollutants were observed at sites situated downstream from Brno, especially at Modřice and Rajhradice. Significant positive correlations (p &lt; 0.05) were found between EROD activity and HCH concentration in SPMDs, and also between GST and EROD activity with HCB concentration in muscle, after adjusting for age. Environ. Toxicol. Chem. 2010;29:541–549. © 2009 SETAC
Enhanced migration of polychlorodibenzo-p-dioxins and furans in the presence of pentachlorophenol-treated oil in soil around utility poles: Screening model validation
Authors: Bulle Cécile , Samson Réjean , Deschênes Louise 
Published: March 2010

Abstract
Field samples were collected around six pentachlorophenol (PCP)-treated wooden poles (in clay, organic soil, and sand) to evaluate the vertical migration of polychlorodibenzo-p-dioxins and furans (PCDD/Fs). Soils were characterized, PCDD/Fs, C10-C50, and PCP were analyzed for seven composite samples located at a depth from 0 to 100 cm and at a distance from 0 to 50 cm from each pole. Concentrations of PCDD/Fs measured in organic soils were the highest (maximum 1.2E + 05 pg toxic equivalent TEQ/g soil), followed by clay (maximum 3.8E + 04 pg TEQ/g soil) and sand (maximum 1.8E + 04 pg TEQ/g soil). Model predictions, including the influence of wood treatment oil, were validated using measured concentration values in soils around poles. The model predicts a migration of PCDD/Fs due to the migration of oil, which differs depending on the type of soil: in clay, 90% of PCDD/Fs are predicted to remain in the first 29 cm, whereas in sand, 80 to 90% of the emitted PCDD/Fs are predicted to migrate deeper than 185 cm. For the organic soil, the predicted migration depth varies from 90 to 155 cm. This screening model allows evaluating the danger of microcontaminated sites around PCP-treated wooden poles: from a risk assessment perspective, in the case of organic soil and clay, no PCDD/F contamination is to be expected below the pole, but high levels of PCDD/Fs can be found in the first 2 m below the surface. For sand, however, significantly lower levels of PCDD/Fs were predicted in the surface soil, while the migration depth remains elevated, posing an inherent danger of aquifer contamination under the pole. Environ. Toxicol. Chem. 2010;29:582–590. © 2009 SETAC