bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mercury contamination of the fish community of a semi-arid and arid river system: Spatial variation and the influence of environmental gradients
Authors: Smith Alexandra , Abuzeineh Alisa A. , Chumchal Matthew M. , Bonner Timothy H. , Nowlin Weston H. 
Published: April 2010

Abstract
Mercury (Hg) contamination of aquatic ecosystems is a global environmental problem. Data are abundant on Hg contamination and factors that affect its bioaccumulation in lake communities, but comparatively little information on riverine ecosystems exists. The present study examines fish Hg concentrations of the Lower Rio Grande/Rio Bravo del Norte drainage, Texas, USA and several of its major tributaries in order to assess whether spatial variation occurs in fish Hg concentrations in the drainage and if patterns of Hg contamination of fish are related to gradients in environmental factors thought to affect Hg concentrations in fish communities. Fish, invertebrates, sediments, and water quality parameters were sampled at 12 sites along the lower Rio Grande/Rio Bravo del Norte drainage multiple times over a one-year period. Spatial variation was significant in fish Hg concentrations when fish were grouped by literature-defined trophic guilds or as stable isotope-defined trophic levels, with highest concentrations found in the Big Bend region of the drainage. Mercury in fish in most trophic guilds and trophic levels were positively related to environmental factors thought to affect Hg in fish, including water column dissolved organic carbon (DOC) and sediment Hg concentrations. It is likely that fish Hg concentrations in the Big Bend region are relatively high because this section of the river has abundant geologic Hg sources and environmental conditions which may make it sensitive to Hg inputs (i.e., high DOC, variable water levels). Results from the present study indicate that Hg contamination of the Rio Grande/Rio Bravo del Norte has substantial implications for management and protection of native small-bodied obligate riverine fish, many of which are imperiled. Environ. Toxicol. Chem. 2010; 29:1762–1772. © 2010 SETAC
Influence of selected antibiotics on the response of black fly (Simulium vittatum) larvae to insecticidal proteins produced by Bacillus thuringiensis subsp. israelensis
Authors: Iburg Joseph P. , Gray Elmer W. , Wyatt Roger D. , Noblet Raymond 
Published: April 2010

Abstract
A controlled current toxicity test (CCTT) was developed to evaluate the response of black fly (Simulium vittatum) larvae to insecticidal proteins following exposure to various antibiotics. The bacterium, Bacillus thuringiensis subsp. israelensis (Bti), produces proteins that are toxic to Nemotoceran Diptera, such as black flies and mosquitoes, when ingested. These insecticidal crystalline proteins (ICPs) are highly efficacious in controlling black flies; however, speculation has arisen regarding the potential for antibiotic contamination of waterways to mitigate the toxicity of these proteins. A series of experiments was conducted with the CCTT in which black fly larvae were exposed to enrofloxacin, tylosin, sulfamethoxazole, and trimethoprim followed by exposure to Bti ICPs. These antibiotics were selected based on their use in agricultural and documented anthropogenic contamination of rivers. Anthropogenic concentrations of a mixture of these four antibiotics did not affect the response of the larvae to Bti ICPs. Subsequent experiments were conducted with antibiotic concentrations 10,000 to 80,000 times higher than those found in contaminated rivers. Exposure of black fly larvae to high levels of enrofloxacin (0.5 mg/L) had no effect upon the susceptibility to Bti ICPs; however, exposure to high levels of tylosin (8 mg/L) resulted in a significant increase in the susceptibility of the larvae to Bti ICPs at 72 h of exposure, but not at 48 h. Exposure of black fly larvae to high concentrations of a mixture of sulfamethoxazole and trimethoprim resulted in a significant increase in the efficacy of the larvicide after 48 and 72 h of exposure. These results suggest that impairment of the efficacy of Bti ICPs to black fly larvae is not due to antibiotic contamination of the larval environment. Environ. Toxicol. Chem. 2010; 29:1849–1853. © 2010 SETAC
Effects of suspended solids and dissolved organic carbon on nickel toxicity
Authors: Cloran Christina E. , Burton G. Allen , Hammerschmidt Chad R. , Taulbee W. Keith , Custer Kevin W. , Bowman Katlin L. 
Published: April 2010

Abstract
Nickel (Ni) is a common and potentially toxic heavy metal in many fluvial ecosystems. We examined the potentially competitive and complementary roles of suspended sediment and a dissolved organic ligand, humate, in affecting the partitioning and toxicity of Ni to a model organism, Daphnia magna, in both batch and stream-recirculating flume (SRF) tests. Sediments included a fine-grained deposit, montmorillonite, and kaolinite. Survival of D. magna was unaffected by the range of suspended solids used in the present study (8–249 mg/L). However, exposure to suspended solids that were amended with Ni had a deleterious effect on test organism survival, which is attributed to partitioning of Ni into the aqueous phase. At comparable levels of dissolved Ni, survival of D. magna was reduced in tests with Ni-amended suspended solids compared to Ni-only aqueous exposures, suggesting potentiation between these two aquatic contaminants. Addition of humate attenuated toxicity to D. magna in both Ni-only and Ni-amended suspended sediment exposures. These results indicate that organic ligands and suspended solids have important functions in affecting the bioavailability and toxicity of Ni to aquatic organisms and should be incorporated into predictive models to protect ecosystem quality. Environ. Toxicol. Chem. 2010; 29:1781–1787. © 2010 SETAC
Telemetry-based field studies for assessment of acute and short-term risk to birds from spray applications of chlorpyrifos
Authors: Wolf Christian , Riffel Michael , Weyman Gabe , Douglas Mark , Norman Steve 
Published: April 2010

Abstract
In a program of avian field studies, radiotelemetry was combined with observations, carcass searches, residue analysis, and determination of brain acetylcholinesterase (AChE) activity to assess the acute and short-term risk posed by chlorpyrifos to birds. Studies were conducted in field crops (brassicas, Poland) and orchards (pome, Italy; citrus, Spain). In total, 25 individual applications of chlorpyrifos were studied on 13 sites. Before each application, birds were fitted with radio transmitters (with minimum stress to birds). Radiotagged birds were monitored and the avifauna observed before, during and for 7 d following each application. A total of 201 birds representing 19 species were radiotagged. In 80% of individual telemetric monitoring periods, birds remained at the study sites. No radiotagged birds showed any sign of intoxication. These included individuals who spent a major proportion of time within treated areas (some individuals located within treated area on &gt;90% of occasions). A total of 7,238 bird sightings were recorded during constant observation during and immediately after application. An additional 4,017 sightings were recorded in 104 individual surveys during 7 d after each application. Two untagged birds (out of 11,255 bird sightings) exhibited atypical behavior for &lt;1 min and 2 to 3 min, respectively, before flying away. This observation (for 0.02% of bird sightings) may or may not have been treatment related. Ten carcasses were recovered (none radiotagged). Residue analysis and brain AChE activity indicated that none was likely to have died from chlorpyrifos exposure. Radiotracking, supported by more traditional assessment methods, was effective for assessing impacts in the field. This extensive field program supports a conclusion that spray applications of chlorpyrifos present a low risk to birds. Environ. Toxicol. Chem. 2010; 29:1795–1803. © 2010 SETAC
Potential role of sea spray generation in the atmospheric transport of perfluorocarboxylic acids
Authors: Webster Eva , Ellis David A. 
Published: April 2010

Abstract
The observed environmental concentrations of perfluorooctanoic acid (PFOA) and its conjugate base (PFO) in remote regions such as the Arctic have been primarily ascribed to the atmospheric transport and degradation of fluorotelomer alcohols (FTOHs) and to direct PFO transport in ocean currents. These mechanisms are each capable of only partially explaining observations. Transport within marine aerosols has been proposed and may explain transport over short distances but will contribute little over longer distances. However, PFO(A) has been shown to have a very short half-life in aqueous aerosols and thus sea spray was proposed as a mechanism for the generation of PFOA in the gas phase from PFO in a water body. Using the observed PFO concentrations in oceans of the Northern Hemisphere and estimated spray generation rates, this mechanism is shown to have the potential for contributing large amounts of PFOA to the atmosphere and may therefore contribute significantly to the concentrations observed in remote locations. Specifically, the rate of PFOA release into the gas phase from oceans in the Northern Hemisphere is calculated to be potentially comparable to global stack emissions to the atmosphere. The subsequent potential for atmospheric degradation of PFOA and its global warming potential are considered. Observed isomeric ratios and predicted atmospheric concentrations due to FTOH degradation are used to elucidate the likely relative importance of transport pathways. It is concluded that gas phase PFOA released from oceans may help to explain observed concentrations in remote regions. The model calculations performed in the present study strongly suggest that oceanic aerosol and gas phase field monitoring is of vital importance to obtain a complete understanding of the global dissemination of PFCAs. Environ. Toxicol. Chem. 2010; 29:1703–1708. © 2010 SETAC
Subcellular distribution of zinc inDaphnia magnaand implication for toxicity
Authors: Wang Wen-Xiong , Guan Rui 
Published: April 2010

AbstractWe examined the subcellular partitioning of zinc (Zn) in Daphnia magna both under acute and chronic exposures. In the acute Zn toxicity tests, the daphnids were exposed to different Zn concentrations for 48 h or to one lethal concentration (1,000 µg/L) for different durations (time to death for up to 47 h). Significant mortality of daphnids was observed when the newly accumulated Zn concentration reached a threshold level of approximately 40 µg/g wet weight (or 320 µg/g dry wt), approximately 3.5 times higher than the background tissue concentration (92 µg/g dry wt). Chronic exposure (14 d) to Zn resulted in nonobservable effect on survivorship and growth at newly accumulated tissue concentration of over 40 µg/g wet weight. With increasing Zn acute exposure, more Zn was partitioned into the cellular debris fraction, indicating that this fraction was presumably the first targeted site of binding for Zn upon entering the animals. The importance of other subcellular fractions either decreased accordingly or remained comparable. We found that the metal-sensitive fraction (Zn distribution in the organelles and heat-denatured proteins) did not predict the acute Zn toxicity in Daphnia. During chronic exposure, however, no major change of the subcellular partitioning of Zn with increasing Zn exposure was documented. Zinc was mainly found in the organelles and heat-stable protein fractions during chronic exposure, suggesting that any subcellular repartitioning occurred primarily during acute exposure. Metallothioneins were induced upon chronic Zn exposure, but its induction evidently lagged behind the Zn accumulation. Our present study showed that the subcellular fractionation approach could not be readily used to predict the acute and chronic toxicities of Zn in Daphnia. A tissue-based Zn accumulation approach with a threshold Zn tissue concentration was better in predicting acute Zn toxicity. Environ. Toxicol. Chem. 2010; 29:1841–1848. © 2010 SETAC
Preexposure to ultraviolet B radiation and 4-tert-octylphenol affects the response ofRana pipienstadpoles to 3,5,3′-triiodothyronine
Authors: Croteau Maxine C. , Duarte-Guterman Paula , Lean David R.S. , Trudeau Vance L. 
Published: April 2010

AbstractExposure to multiple environmental stressors is negatively impacting the health of amphibians worldwide. Increased exposure to ultraviolet B radiation (UVBR) and chemical pollutants may affect amphibian populations by disrupting metamorphosis; however, the actual mechanisms by which these stressors affect development remain unknown. Because amphibian metamorphosis is controlled by thyroid hormones (TH), changes in developmental rates by environmental stress suggest a disruption of the thyroid system. Tadpoles were chronically exposed to environmental levels of UVBR (average of 0.15 W/m2) and 4-tert-octylphenol (OP; 10 nM), alone and combined, prior to being challenged to exogenous TH triiodothyronine (T3; 5 or 50 nM). This experimental approach was taken to determine whether exposure to these stressors affects the ability of T3 to elicit specific molecular and morphological responses. Exposure to OP increased mRNA levels of thyroid receptors (TRs) alpha and beta, deiodinase type 2 (D2), and corticotropin releasing hormone in the brain and of D2 in the tail of tadpoles. 4-tert-octylphenol also enhanced T3-induced expression of D2 in the brain. The combination of UVBR and OP affected the expression of TR alpha in the brain and the responses of TR alpha and beta genes to T3 in the tail, demonstrating the importance of considering the effects of multiple stressors on amphibians. Tadpoles exposed to UVBR were developmentally delayed and exhibited slowed tail resorption and accelerated hindlimb development following exposure to T3. Together, these findings indicate that UVBR alters the rate of development and TH-dependent morphological changes at metamorphosis, and that exposure to UVBR and/or OP disrupts the expression of genes important for development and the biological action of T3 in peripheral tissues. Our group is the first to demonstrate that environmental levels of UVBR and/or OP can affect the thyroid system of amphibians. Environ. Toxicol. Chem. 2010; 29:1804–1815. © 2010 SETAC
Improving emissions estimates of home and personal care products ingredients for use in EU risk assessments
Authors: Price Oliver R , Hughes Gregory O , Roche Nicola L , Mason Paul J 
Published: April 2010

Abstract
REACh introduces environmental release categories (ERCs) used to describe chemical emissions to the environment. These ERCs contain a number of default values that are combined with product usage data to estimate environmental exposure concentrations for use in risk assessment. The methodology presented in the present work constitutes a novel approach that allows for the coupling of population density and country-specific usage statistics for a range of home and personal care products. Spatially explicit usage estimates are presented for European Union (EU) hypothetical regions (200 × 200-km grid), as described in EU risk assessment frameworks. Recent sales and population density data are combined to assess the relevance of current default assumptions; that 10% of a product will be used in an EU hypothetical region that is inhabited by 20 million people. It is demonstrated that these assumptions are conservative and their relevance geographically limited. The highest usage estimates for hypothetical regions are located in southern England and a transboundary area in Europe consisting of Belgium, the Netherlands, and Germany. The maximum identified usage of 9 home and personal care product types, in an EU hypothetical region, ranges from 4.3% to 11.4%. The 99.5th percentile values, representative of an EU hypothetical region with a population of 20 million, range from 3.6% to 9.0%, which suggests that the current default parameterization of the ERCs may be overly protective for ingredients used in a number of home and personal care product types. Accordingly, it may be justified to use such an analysis to refine the default values in order to provide more realistic exposure estimates for use in REACh assessments. Integr Environ Assess Manag 2010;6:677–684. © 2010 SETAC
Environmental effect assessment for sexual endocrine-disrupting chemicals: Fish testing strategy
Authors: Knacker Thomas , Boettcher Melanie , Frische Tobias , Rufli Hans , Stolzenberg Hans-Christian , Teigeler Matthias , Zok Sabine , Braunbeck Thomas , Schäfers Christoph 
Published: April 2010

Abstract
Current standard testing and assessment tools are not designed to identify specific and biologically highly sensitive modes of action of chemicals, such as endocrine disruption. This information, however, can be important to define the relevant endpoints for an assessment and to characterize thresholds of their sublethal, population-relevant effects. Starting a decade ago, compound-specific risk assessment procedures were amended by specifically addressing endocrine-disrupting properties of substances. In 2002, the Conceptual Framework, agreed upon by OECD's Task Force on Endocrine Disrupters Testing and Assessment, did not propose specific testing strategies, and appropriate testing methods had not yet been developed and approved. In the meantime, the OECD Test Guidelines Programme has undertaken important steps to revise established and to develop new test methods, which can be used to identify and quantify effects of endocrine-disrupting chemicals on mammals, birds, amphibians, fish, and invertebrates. For fish testing of endocrine-disrupting chemicals, the first Test Guidelines have recently been adopted by the OECD and validation of further test systems is under progress. Based on these test systems and the experience gained during their validation procedures, we propose a 3-step fish testing strategy: 1) Weight-of-evidence approach for identifying potential sexual endocrine-disrupting chemicals; even after advanced specification of systematic criteria, this step of establishing initial suspicion will still require expert judgment; 2) in vivo evaluation of sexual endocrine-disrupting activity in fish by applying in vivo fish screening assays; sufficient data are available to diagnose the aromatase-inhibition and estrogen-receptor agonist mechanisms of action by indicative endpoints (biomarkers), whereas the ability of the respective biomarkers in the screening assay to identify the estrogen-receptor antagonists and androgen-receptor agonists and antagonists requires further validation; 3) characterization of sexual endocrine-mediated adverse effects including threshold concentrations; in cases when the most sensitive population-relevant endpoints and the most sensitive time window for exposure are known for the mechanisms of action, the fish full life-cycle or 2-generation test, which are the normal definitive tests, might be abbreviated to, e.g., the fish sexual development test. In the European Union, the measurement of indicative endpoints in the definitive test might be crucial for the authorization procedure under REACH and plant-protection products. The results of the definitive tests can be used in existing schemes of compound-specific environmental risk assessments. Integr Environ Assess Manag 2010;6:653–662. © 2010 SETAC
Environmental risk assessment of ivermectin: A case study
Authors: Liebig Markus , Fernandez Álvaro Alonso , Blübaum-Gronau Elke , Boxall Alistair , Brinke Marvin , Carbonell Gregoria , Egeler Philipp , Fenner Kathrin , Fernandez Carlos , Fink Guido , Garric Jeanne , Halling-Sørensen Bent , Knacker Thomas , Krogh Kristine A , Küster Anette , Löffler Dirk , Cots Miguel Ángel Porcel , Pope Louise , Prasse Carsten , Römbke Jörg , Rönnefahrt Ines , Schneider Manuel K. , Schweitzer Natascha , Tarazona José V , Ternes Thomas A , Traunspurger Walter , Wehrhan Anne , Duis Karen 
Published: April 2010

AbstractThe veterinary parasiticide ivermectin was selected as a case study compound within the project ERAPharm (Environmental Risk Assessment of Pharmaceuticals). Based on experimental data generated within ERAPharm and additional literature data, an environmental risk assessment (ERA) was performed mainly according to international and European guidelines. For the environmental compartments surface water, sediment, and dung, a risk was indicated at all levels of the tiered assessment approach. Only for soil was no risk indicated after the lower tier assessment. However, the use of effects data from additional 2-species and multispecies studies resulted in a risk indication for collembolans. Although previously performed ERAs for ivermectin revealed no concern for the aquatic compartment, and transient effects on dung-insect populations were not considered as relevant, the present ERA clearly demonstrates unacceptable risks for all investigated environmental compartments and hence suggests the necessity of reassessing ivermectin-containing products. Based on this case study, several gaps in the existing guidelines for ERA of pharmaceuticals were shown and improvements have been suggested. The action limit at the start of the ERA, for example, is not protective for substances such as ivermectin when used on intensively reared animals. Furthermore, initial predicted environmental concentrations (PECs) of ivermectin in soil were estimated to be lower than refined PECs, indicating that the currently used tiered approach for exposure assessment is not appropriate for substances with potential for accumulation in soil. In addition, guidance is lacking for the assessment of effects at higher tiers of the ERA, e.g., for field studies or a tiered effects assessment in the dung compartment. Integr Environ Assess Manag 2010;6:567–587. © 2009 SETAC
Effects of asenapine on prefrontalN‐methyl‐D‐aspartate receptor‐mediated transmission: Involvement of dopamine D1 receptors
Authors: Jardemark Kent , Marcus Monica M. , Shahid Mohammed , Svensson Torgny H. 
Published: April 2010

AbstractAsenapine is a novel psychopharmacologic agent being developed for schizophrenia and bipolar disorder. Like clozapine, asenapine facilitates cortical dopaminergic andN‐methyl‐D‐aspartate (NMDA) receptor‐mediated transmission in rats. The facilitation of NMDA‐induced currents in cortical pyramidal cells by clozapine is dependent on dopamine and D1receptor activation. Moreover, previous results show that clozapine prevents and reverses the blockade of NMDA‐induced currents and firing activity in the pyramidal cells by the noncompetitive NMDA receptor antagonist phencyclidine (PCP). Here, we investigated the effects of asenapine in these regards using intracellular electrophysiological recording in vitro. Asenapine (5 nM) significantly facilitated NMDA‐induced currents (162 ± 15% of control) in pyramidal cells of the medial prefrontal cortex (mPFC). The asenapine‐induced facilitation was blocked by the D1receptor antagonist SCH23390 (1 μM). Furthermore, the PCP‐induced blockade of cortical NMDA‐induced currents was effectively reversed by 5 nM asenapine. Our results demonstrate a clozapine‐like facilitation of cortical NMDA‐induced currents by asenapine that involves prefrontal dopamine and activation of D1receptors. Asenapine and clozapine also share the ability to reverse functional PCP‐induced hypoactivity of cortical NMDA receptors. The ability of asenapine to increase both cortical dopaminergic and NMDA receptor‐mediated glutamatergic transmission suggests that this drug may have an advantageous effect not only on positive symptoms in patients with schizophrenia, but also on negative and cognitive symptoms. Synapse 64:870–874, 2010. © 2010 Wiley‐Liss, Inc.