bluuebunny/crossref_metadata_2025_split huggingface dataset:
A critical surface area concept for acute hazard classification of relatively insoluble metal-containing powders in aquatic environments
Authors: Skeaff Jim , Delbeke Katrien , Van Assche Frank , Conard Bruce 
Published: March 2010

Abstract
A method is proposed for determining the hazard identification, based on acute aquatic toxicity, and subsequent classification if necessary, of metals and sparingly soluble inorganic metal compounds. The method is based on establishing a relationship between the measured reaction kinetics of the substance with an aqueous medium and the measured surface area of the substance loaded to the medium. The total dissolved metal concentration at a given time expressed as a function of measured surface area is then compared with an appropriate acute toxicity value, the median lethal effective concentration (L(E)C50), as measured in standard toxicity tests with the corresponding soluble metal salt to yield a critical surface area independent of particle size that will deliver the L(E)C50 to the medium. The critical surface area can then be converted to the conventional 100, 10, and 1 mg/L cutoff points to calculate a hazard identification line that can be used straightforwardly thereafter to establish the hazard classification of any form of the substance once its specific surface area is measured. Further transformation testing of the forms that the substance may be produced in is not required. The application of the critical surface area method to determine the hazard classification according to specific surface area is illustrated by worked examples for nickel metal and zinc metal. Selection of appropriate L(E)C50 values is critical, because different values can substantially change the final classification.
Oral bioavailability and toxicokinetics of 3,3′,4,4′,5-pentachlorobiphenyl in northern leopard frogs,Rana pipiens
Authors: Huang Yue-wern , Karasov William H 
Published: March 2010

AbstractThis study is the first report on oral bioavailability, whole-body elimination, and distribution of a specific polychlorinated biphenyl (PCB) congener on an amphibian species, northern leopard frogs. Each frog was orally dosed once with either 0.35 or 5.0 mg/kg PCB 126 (based on frog wet wt), including tracer 14C-PCB 126 (3′,4′,5′-phenyl-ring-14C) by force feeding it a cricket injected with the PCB. We found no statistical difference (t = 0.917, df = 5, p = 0.401) in the average 48-h oral bioavailabilities of 0.35- and 5.0-mg/kg dosage groups, which were 84.6 ± 5.8% (mean ± SE, n = 4) and 90.9 ± 1.5% (n = 3), respectively. Statistical analysis indicated that time was the only independent variable affecting the retention of whole-body 14C content. Kinetics were apparently first order because elimination rate was independent of dose. Assuming a single pool and one elimination rate, the t1/2 value for whole-body elimination of PCB-derived 14C was 763 d. Liver, fat bodies (corpora adiposa), carcass (head, bone, cartilage materials, and residues of other tissues), skin, and muscle were the major organs for PCB 126 retention in both dosage groups. The concentrations of 14C residue in fat bodies were relatively constant throughout the experiment. However, total residues in fat bodies declined throughout the experiment in both dosage groups in correlation with declining masses of fat bodies. Gonad, kidney, stomach, intestine, and a tissue pool including esophagus, lung, spleen, heart, and cloacal materials each accumulated &lt;1% of the initial total 14C residue. The egg follicles in 19 females contained 1 to 23% of the initial total 14C residue, with an average of 10.0 ± 9.2% (mean ± SE, n = 19).
Evaluation of sensitivity and specificity of two crustacean biochemical biomarkers
Authors: McLoughlin Nathan , Yin Daqiang , Maltby Lorraine , Wood Robert M , Yu Hongxia 
Published: March 2010

AbstractBiochemical biomarkers are increasingly used for environmental assessment. Although the emphasis has been on vertebrate biomarkers, invertebrates biomarkers have been developed as well. This study evaluated the usefulness of biomarker responses of freshwater invertebrates by comparing the sensitivity and specificity of endpoints at three levels of biological organization: biochemical, physiological, and individual. The study focused on the epibenthic amphipod Gammarus pulex L., and the end points were cholinesterase (ChE) and glutathione-S-transferase (GST) activity, feeding inhibition, and mortality. Chemicals representing five major classes of toxic chemicals were assessed, including zinc, linear alkylbenzene sulphonate (LAS; surfactant), lindane (organochlorine), pirimiphos-methyl (organophosphorus), and permethrin (pyrethroid). Lethality was the least sensitive endpoint, with 96-h LC50 values ranging from 2.78 μg/L for permethrin to 6.31 mg/L for LAS. Comparison of the biochemical biomarkers and the sublethal feeding rate assay indicated that whereas ChE inhibition was a specific indicator of organophosphate exposure, the biochemical assay was more than 13-fold less sensitive than the feeding rate assay. The GST biomarker performed with greater sensitivity but with lower specificity compared with the ChE biomarker. However, only on exposure to lindane did the GST biomarker marginally outperform the feeding rate assay in terms of sensitivity. Feeding inhibition is both a general and a sensitive (LC50, &lt;3%) indicator for exposure to a range of chemicals. The Gammarus sp. ChE biomarker may have utility in providing a diagnostic and rapid indicator of organophosphate exposure, but evidence from this and other studies questions the sensitivity of this biomarker in predicting sublethal, higher-order effects. The GST biomarker may provide a rapid and sensitive indicator for toxicant exposure, but it has limited use as a diagnostic tool and provides only limited improvement in sensitivity over more ecologically relevant sublethal end points (e.g., feeding rate, growth rate).
Constants of mercury methylation and demethylation rates in sediments and comparison of tracer and ambient mercury availability
Authors: Hintelmann Holger , Keppel-Jones Katherine , Evans R Douglas 
Published: March 2010

Abstract
A method was developed to measure mercury methylation and demethylation rate constants simultaneously in aquatic samples. Solutions containing stable isotope tracers of 199Hg2+ and CH3202Hg+ were spiked into lake sediments at subambient concentrations. The formation of CH3199Hg+ and the decrease in CH3202Hg+ were measured simultaneously in time series experiments using gas chromatographic separation and isotope-specific detection by inductively coupled plasma mass spectrometry. Specific rate constants for the two processes were calculated and compared to rate constants obtained by monitoring changes in concentration of the ambient methylmercury in the same sample. The inorganic mercury tracer 199Hg2+ was methylated at a faster rate compared with the ambient inorganic Hg2+, which indicates that the added tracer Hg2+ is more available for transformation reaction than the ambient Hg2+. The degradation of tracer and ambient methylmercury proceeded at a similar rate, showing no significant differences between added tracer and ambient methylmercury. The calculated half-life for methylmercury in sediments was 1.7 d, suggesting a rapid turnover and low persistence of methylmercury in lake sediments. Different Hg species were investigated regarding their availability for methylation reactions. Compared to Hg(NO3)2, Hg-fulvate showed reduced availability and freshly precipitated HgS was hardly available.
Comparison of pesticides in eight U.S. urban streams
Authors: Hoffman Ryan S , Capel Paul D , Larson Steven J 
Published: March 2010

Abstract
Little is known of the occurrence of pesticides in urban streams compared to streams draining agricultural areas. Water samples from eight urban streams from across the United States were analyzed for 75 pesticides and seven transformation products. For six of the eight urban streams, paired agricultural streams were used for comparisons. The herbicides detected most frequently in the urban streams were prometon, simazine, atrazine, tebuthiuron, and metolachlor, and the insecticides detected most frequently were diazinon, carbaryl, chlorpyrifos, and malathion. In contrast to similar-sized agricultural streams, total insecticide concentrations commonly exceeded total herbicide concentrations in these urban streams. In general, the temporal concentration patterns in the urban streams were consistent with the characteristics of the local growing season. The insecticides carbaryl and diazinon exceeded criteria for the protection of aquatic life in many of the urban streams in the spring and summer. When the country as a whole is considered, the estimated mass of herbicides contributed by urban areas to streams is dwarfed by the estimated contribution from agricultural areas, but for insecticides, contributions from urban and agricultural areas may be similar. The results of this study suggest that urban areas should not be overlooked when assessing sources and monitoring the occurrence of pesticides in surface waters.
Fixed-effect-level toxicity equivalents—a suitable parameter for assessing ethoxyresorufin-O-deethylase induction potency in complex environmental samples
Authors: Brack Werner , Segner Helmut , Möder Monika , Schüürmann Gerrit 
Published: March 2010

Abstract
Within the scope of bioassay-directed identification of dioxin-like toxicants in complex environmental samples, EC50-based and fixed-effect-level-based 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity equivalents (TEQs) were compared to assess 7-ethoxyresorufin-O-deethylase (EROD) inducing potency of sediment fractions using the rainbow trout liver cell line RTL-W1 as bioassay system. Toxicity equivalents on the basis of fixed effect levels are suggested in order to minimize interpretation problems due to the superposition of enzyme-inducing and enzyme-inhibiting effects. Bioassay-directed fractionation of a contaminated sediment extract in the industrial region of Bitterfeld (Germany) based on fixed-effect-level TEQs indicated high dioxin-like activity in the lipophilic sediment fractions containing the prototypic arylhydrocarbon receptor (AhR) agonists polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). However, only a small part of the EROD induction could be attributed to the PCBs and PAHs that were analyzed. Significant EROD induction occurred also with some of the more polar fractions.
Oocytic accumulation and tissue distribution of 2,3,7,8-tetrachlorodibenzo-p-dioxin and benzo[a]pyrene in gravid Fundulus heteroclitus
Authors: Monteverdi George H , DiGiulio Richard T 
Published: March 2010

Abstract
These studies investigated the maternal transfer of xenobiotic ligands in the estuarine mummichog (Fundulus hetero-clitus). The common environmental contaminants 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and benzo[a]pyrene (B[a]P) were shown to accumulate in maturing oocytes of gravid F. heteroclitus. In vivo, time-course experiments with gravid female fish demonstrated time- and dose-dependent changes in oocytic accumulation of 3H-TCDD and 14C-B[a]P. In studies with 14C-B[a] P, both total radiochemical content and the composition of 14C-B[a]P metabolites in these extracts presented an accumulation profile that mirrored the profiles observed in sera from dosed fish reported previously. Furthermore, the accumulation of both 3H-TCDD and 14C-B[a]P was related to oocyte maturational state (i.e., size) and, correspondingly, to vitellogenin (VTG) uptake. Although VTG uptake is critical for proper oocyte growth and early-life-stage development, analysis of these data suggests an additional role for VTG as a vector of maternal transfer for both 3H-TCDD and 14C-B[a]P. This conclusion is also supported by an accompanying paper, presented in this volume, that examined the association of VTG with TCDD and B[a] P.
Effects of white phosphorus on mallard reproduction
Authors: Vann Stephanie L , Parling Donald W S , Ottinger Mary Ann 
Published: March 2010

Abstract
Extensive waterfowl mortality involving thousands of ducks, geese, and swans has occurred annually at Eagle River Flats, Alaska, USA, since at least 1982. The primary agent for this mortality has been identified as white phosphorus. Although acute and subacute lethality have been described, sublethal effects are less well known. This study reports on the effects of white phosphorus on reproductive function in the mallard (Anas platyrhynchos) in captivity. Fertility, hatching success, teratogenicity, and egg laying frequency were examined in 70 adult female mallards who received up to seven daily doses of 0, 0.5, 1.0, and 2.0 mg/kg of white phosphorus. Measurements of fertility and hatchability were reduced by the white phosphorus. Teratogenic effects were observed in embryos from hens dosed at all treatment levels. Egg laying frequency was reduced even at the lowest treatment level; treated hens required a greater number of days to lay a clutch of 12 eggs than control hens. After two doses at 2.0 mg/kg, all females stopped laying completely for a minimum of 10 d, and laying frequency was depressed for at least 45 d. Fertility of 10 adult male mallards dosed with 1.0 mg/kg of white phosphorus did not differ from 10 controls, but plasma testosterone levels were significantly (p &lt; 0.05) reduced in the treated males 1 d after dosing ended. These results provide evidence that productivity of free-ranging mallards may be impaired if they are exposed to white phosphorus at typical field levels.
Effects of the sulfonylurea herbicide metsulfuron methyl on growth and reproduction of five wetland and terrestrial plant species
Authors: Boutin Céline , Lee Hing-Biu , Peart E Thomas , Batchelor P Suzanne , Maguire R James 
Published: March 2010

Abstract
Two wetland plant species (Mimulus ringens L. [monkey-flower] and Bidens cernua L. [bur-marigold]), two terrestrial species (Sinapis arvensis L. [wild mustard] and Phaseolus vulgaris L. [beans-variety, Kentucky blue]), and one species found in both wet and dry habitats (Echinochloa crusgalli [L.] Beauv. [barnyardgrass]) were exposed to 1% (0.045 g a.i./ha) and 10% (0.45 g a.i./ha) of recommended label rate of metsulfuron methyl, a sulfonylurea herbicide used in western Canada. The objective of the study was to investigate the effect of metsulfuron methyl on these plant species and to determine the most sensitive phenological stage. Chemical analyses of herbicide residues showed that there was good correspondence between the quantity measured in the tank mix compared with that detected on glass fiber papers, the latter representing the dose reaching the test plants during the spray event. All species exhibited marked effects on the vegetative growth and reproductive performance when sprayed at 10% label rate. Less pronounced but significant effects were shown at 1% label rate. Seed weight was reduced for B. cernua and S. arvensis. The seedling stage was the most sensitive period for all species tested, although surviving plants sprayed at later stages showed considerable effects on the reproductive parts. All species tested would be at risk from small doses of metsulfuron methyl drifting away from the sprayed areas. This study highlights the shortcomings of the current testing schemes required prior to pesticide registration.
Effects of copper on reproduction of two collembolan species exposed through soil, food, and water
Authors: Pedersen Marianne Bruus , van Gestel Cornelis AM , Elmegaard Niels 
Published: March 2010

Abstract
Extrapolation of laboratory toxicity data to the field is hampered by differences in bioavailability, among other factors. Often, chemical availability of substances in the soil pore water is considered equivalent to bioavailability. However, for collembolans, which are not closely connected with the water phase of the soil, the situation may be different since other routes of exposure may also be of importance. In the present study, two species of Collembola, Folsomia candida Willem and Folsomia fimetaria L., were exposed to copper sulfate in different ways, for example, in aqueous solutions, in spiked soil, in soil from a copper-contaminated field site, and via the food supply (yeast). Reproduction of the collembolans was inhibited at elevated soil or yeast copper concentrations. The 10% effective concentration (EC10) values for freshly spiked soil were 50 [0.03–13,095] and 141 [20–1,001] mg/kg for F. candida and F. fimetaria, and the corresponding values for yeast exposure were 2,900 [613–13,877] and 361 [0.1–972,864] mg/kg (95% confidence limits in square brackets). Soil from the contaminated field site had no effects on reproduction at copper concentrations up to 2,500 mg/kg. Internal copper concentrations were constant up to a soil copper concentration between 400 and 800 mg/kg in newly spiked soil and up to between 1,400 and 2,500 mg/kg in field soil. Copper accumulation in the animals from freshly spiked soil was higher than from yeast, and accumulation from both routes appeared to be additive. Spiked soil resulted in higher accumulation than soil from a contaminated field site. Addition of clean yeast to spiked soil resulted in a decrease in copper accumulation. The two collembolan species accumulated comparable concentrations from soil, whereas F. candida accumulated more copper from contaminated yeast placed on top of unpolluted soil than F. fimetaria. Male F. fimetaria accumulated more copper from contaminated soil than females. When exposed through yeast, the two sexes accumulated similar concentrations. A link between internal copper concentrations and effects on reproduction was difficult to establish because of large variations in both parameters and because effects seemed to begin at soil and yeast copper concentrations where internal concentrations were still regulated. Consequently, the establishment of a fixed internal threshold was uncertain.
Multivariate test designs to assess the influence of zinc and cadmium bioavailability in soils on the toxicity to Enchytraeus albidus
Authors: Lock Koen , Janssen Colin R , De Coen Wim M 
Published: March 2010

Abstract
Multivariate test designs were used to identify and quantify the soil parameters important for determining the ecotoxicological effects of zinc and cadmium to the potworm Enchytraeus albidus. The application of a fractional factorial design (FFD) revealed that the acute toxicity of zinc and cadmium to E. albidus can vary over more than two orders of magnitude, depending on the composition of the (artificial) soils. The differences in metal ecotoxicity were determined mainly by pH and organic matter content or cation exchange capacity (CEC). Using a central composite design, models were developed describing the ecotoxicity of zinc and cadmium to E. albidus as a function of these parameters. To validate the developed surface response models, two field soils and the standard artificial soil prescribed by the Organization for Economic Cooperation and Development (OECD) were spiked with zinc and cadmium, and the acute toxicity to E. albidus was assessed. These validation experiments confirmed that the toxicity of zinc and cadmium could be predicted by the pH and the CEC of a soil with toxicity decreasing with increasing pH and CEC.
Anthracene photoinduced toxicity to plhc-1 cell line (Poeciliopsis lucida) and the role of lipid peroxidation in toxicity
Authors: Choi Jonghoon , Oris James T 
Published: March 2010

Abstract
Many polycyclic aromatic hydrocarbons (PAHs) are acutely toxic to fish and other aquatic organisms in the presence of solar ultraviolet radiation (SUVR) of environmentally realistic intensities. In the present study, the photoinduced toxicity of a PAH (anthracene; ANT) to topminnow hepatoma cell line (PLHC-1) was assessed. After the toxicity was characterized, the role of lipid peroxidation in PAH photoinduced toxicity was examined by measuring lipid peroxidation products and by assessing the effect of lipid peroxidation antagonist (Trolox) treatment. In cytotoxicity tests using two assays (MTT, neutral red), the SUVR/ANT treatment elicited toxicity to PLHC-1 cells in a concentration- and SUVR (exposure duration and intensity)-dependent pattern. As found in previous organism-level studies, no significant cytotoxicity was observed in the cells exposed either to fluorescent light/ANT or to SUVR only. The SUVR/ANT treatment elicited the lipid peroxidation process and Trolox pretreatment significantly reduced SUVR/ANT-induced cell mortality. Microscopic observation showed that Trolox pretreatment relieved the SUVR/ANT-inflicted damage, such as cell shrinkage and membrane disruption. Together with a recent finding in our lab that increased production of superoxide anion and a lipid peroxidation product (malondialdehyde) was found in SUVR/ANT-treated fish microsomes, the present study suggests that reactive oxygen radical-induced lipid peroxidation is an important factor in PAH photoinduced toxicity to fish.
Effects of polycyclic aromatic hydrocarbons on expression of cyp1a in salmon (Salmo salar) following experimental exposure and after the Braer oil spill
Authors: Stagg Ronald M , Rusin Jan , McPhail Mary E , McIntosh Alistair D , Moffat Colin F , Craft John A 
Published: March 2010

Abstract
The induction of hepatic CYP1A by selected polycyclic aromatic hydrocarbons (PAHs) was followed in Atlantic salmon (Salmo salar) by measurement of CYP1A messenger RNA (mRNA), CYP1A protein levels, and catalytically by the measurement of 7-ethoxyresorufin-O-deethylase activity. There was clear correspondence between all three methods of measurement both in terms of the specificity of response to five- and some four-ring PAHs and in terms of the dose-response relationship to methyl-cholanthrene. The level of induction was compared with that measured in salmon confined in sea pens around Shetland and exposed to crude oil spilled from the Braer in January 1993. This oil was rapidly dispersed by the extreme weather (turbulence) at the time of the spill. The time course of the hepatic CYP1A induction was followed and related to the levels of oil measured in water and the concentration of PAHs determined in the flesh of the fish. Again there was a good correspondence between the different methods of measuring CYP1A expression, and the results show a rapid induction response in fish at the most contaminated sites and small, insignificant changes occurring at the reference stations. There was a clear concentration response between CYP1A and catalytic activity and between the exposure observed.