bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproductive toxicity and disposition of 2,3,7,8-tetrachlorodibenzo-p-dioxin in adult brook trout (Salvelinus fontinalis) following a dietary exposure
Authors: Tietge Joseph E , Johnson Rodney D , Jensen Kathleen M , Cook Philip M , Elonen Gregory E , Fernandez Joseph D , Holcombe Gary W , Lothenbach Douglas B , Nichols John W 
Published: March 2010

AbstractAult brook trout (Salvelinus fontinalis) were exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with a contaminated trout pellet diet to determine the effects of TCDD on reproduction, to document tissue-specific TCDD distribution, and to establish the maternally derived dose of TCDD to the F1 generation. Five treatment groups and a control were exposed to achieve targeted whole body TCDD concentrations of 0, 75, 150, 300, 600, and 1,200 pg TCDD per gram fish. Net dietary assimilation of TCDD was estimated to be 89% of the applied dose, and the distribution of TCDD generally followed the distribution of lipids in liver, gonad, fat, blood, and muscle. Depuration could not be measured over 81 d, but a hypothetical depuration rate was estimated to be 0.002 d−1 assuming 100% dietary assimilation. The concentration of TCDD in ovaries and spawned eggs was estimated to be 61 and 39% of the whole body TCDD concentrations, respectively. Survival, growth, gonadal development, and egg production were not affected in any treatment. The onset of spawning was delayed by 13 d in the highest treatment group, suggesting that TCDD might have affected ovulation. Otherwise, the adult life stage was not as sensitive to TCDD as the early life stage.
Historical impacts of environmental regulation of silver
Authors: Purcell Thomas W , Peters Jennifer J 
Published: March 2010

Abstract
Exposure to silver, and hence its possible environmental effects, has been regulated since the 1960s. Rules were first developed in the United States to protect against potential negative effects to humans due to ingestion of drinking water containing silver. As regulations for other environmental media were developed, silver was generally included because of its designation as a drinking water chemical of concern. Ambient water quality criteria were developed based on the toxic action of ionic silver. In the early 1990s the U.S. Environmental Protection Agency's Office of Drinking Water downgraded silver from a primary to a secondary maximum contaminant level because the effects of exposure to silver were judged to be cosmetic. Regulations pertaining to solid waste, surface waters, and occupational exposure have not been changed, but may be changed in the near future as the fate and toxic mechanisms of silver become better understood.
Effects of altering freshwater chemistry on physiological responses of rainbow trout to silver exposure
Authors: Bury Nicolas R , McGeer James C , Wood Chris M 
Published: March 2010

Abstract
The influence of different water Cl− (50–600 μM), Ca2+ (50–1, 500 μM), Na+ (50–1, 500 μM), or dissolved organic carbon (DOC, 0.31–5 mg/L) levels on silver-induced physiological and biochemical perturbations of rainbow trout were investigated. Fish were acclimated to soft water (50 μM; Cl−, Ca2+, and Na+), then exposed to 3.7 μg/L Ag (as AgNO3) for 6 h, which resulted in a reduction in Na+ influx from the water, an inhibition of gill sodium- and potassium-activated adenosine triphosphatase (Na+/K+-ATPase) activity, and an accumulation of silver on the gills. Increasing the water Cl− or DOC levels ameliorated the silver toxicity. However, increasing water Ca2+ or Na+ concentration did not reduce the silver-induced physiological and biochemical perturbations. The free silver ion (Ag+) concentrations (calculated from MINEQL+, a geochemical speciation computer program) showed a negative correlation with the Na+ influx rates and gill Na+/K+-ATPase activity. However, gill silver levels did not correlate to Ag+ concentrations and no correlation was found between gill silver levels and either Na+ influx rates or gill Na+/K+-ATPase activity. These results support the notion that the [Ag+] concentration is of major importance when assessing silver toxicity in fish, and that this should be taken into account in regulatory strategies for silver in the natural environment.
Physiology and modeling of mechanisms of silver uptake and toxicity in fish
Authors: Wood Chris M , Playle Richard C , Hogstrand Christer 
Published: March 2010

Abstract
In this review, we outline the physiological and toxicological effects of silver (Ag) in freshwater and marine fish. For freshwater fish, the acute toxicity of Ag appears to be caused solely by ionic Ag+ interacting at the gills, inhibiting basolateral Na+, K+-ATPase activity. Disruption of this enzyme inhibits active Na+ and Cl− uptake and therefore osmoregulation by the fish. Silver is much less toxic to marine fish, mainly because ionic Ag+ is complexed by Cl−, but the mechanisms of acute toxicity and the toxic species of Ag are poorly understood. Osmoregulatory failure occurs in marine fish exposed to high concentrations of Ag, and the intestine appears to be a primary toxic site of action, perhaps along with a gill component. Modeling approaches to calculate Ag interactions at biological surfaces are used to illustrate the effects of water chemistry on Ag speciation and therefore toxicity to freshwater and marine fish. In these models, the most important components affecting Ag speciation are the complexing agents Cl− and dissolved organic matter followed by the competing agents Na+ and Ca2+, although a particulate component may be important to incorporate into the models in future. More precise knowledge of the actual toxic sites of Ag is necessary if we are to fully understand the effects of waterborne Ag in the environment.
Use of Ulva Lactuca to distinguish pH-dependent toxicants in marine waters and sediments
Authors: Ho Kay T , Kuhn Anne , Pelletier Marguerite C , Burgess Robert M , Helmstetter Andrea 
Published: March 2010

Abstract
Ulva lactuca (sea lettuce) is a cosmopolitan marine attached green seaweed capable of sequestering high environmental levels of ammonia. Ammonia can be acutely toxic to marine organisms and is often found in dredged sediments from highly industrial areas or from areas with high carbon inputs. For the purposes of dredged sediment disposal as well as in determining causes of toxicity in complex mixtures, it is important to distinguish ammonia toxicity from the toxicity of other compounds. The use of U. lactuca to selectively remove ammonia from waters and sediments as part of a toxicity identification and evaluation (TIE) procedure was evaluated. Ulva lactuca lowered concentrations of total ammonia from 75 to 17 mg/L in &lt;8 h in water-only exposures. This treatment also reduced 48-h amphipod mortality from 75 to 20%. In whole sediments, U. lactuca lowered interstitial water concentrations of ammonia from 60 to 20 mg/L, while keeping overlying water concentrations below detectable limits (&lt;1 mg/L). To determine the limitations of the U. lactuca method to selectively remove ammonia from solution, metal and organic accumulation experiments were performed. Ulva lactuca generally took up &lt;15% of metals present, with most of the exposures resulting in less than a 10% uptake. In contrast, U. lactuca removed 77% of lindane and 95% of fluoranthene. Results of a TIE conducted on sediments from an industrial marine harbor indicated U. lactuca was useful, in conjunction with other procedures, in categorizing ammonia as a sediment toxicant.
Bioconcentration, biotransformation, and chronic toxicity of sodium laurate to zebrafish (Danio rerio)
Authors: van Egmond Roger , Hambling Susan , Marshall Stuart 
Published: March 2010

Abstract
The chronic toxicity of sodium laurate (dodecanoic acid, sodium salt; CAS 629-25-4) to zebrafish (Danio rerio) was determined in a 28-d growth rate study. The laurate did cause lethal effects, but a reduction in growth was not observed at sublethal exposure concentrations. The 15-d median lethal concentration was 7.6 mg/L, which is similar to the theoretical and measured solubility limit of laurate under the test conditions. The 28-d no-observed-effect concentration (lethality) was 2 mg/L, whereas growth was not impaired at 6.4 mg/L in survivors after 28 d. Laurate was extensively biotransformed to metabolites, including less polar compounds, possibly triacylglycerols. At the end of the exposure period, which was considered long enough for steady state to be achieved, the bioconcentration factor of laurate was estimated to be 255 L/kg. Body burdens of nonmetabolized laurate for surviving fish were up to 10-fold higher (2.7–8.7 mmol/kg) than the chronic critical (sublethal) body residues (0.2–0.8 mmol/ kg) proposed for nonpolar or polar narcotics.
New testing apparatus for assessing interactive effects of suspended solids and chemical stressors on plankton invertebrates
Authors: Herbrandson Carl , Bradbury Steven P , Swackhamer Deborah L 
Published: March 2010

Abstract
To better predict and interpret the responses of aquatic organisms to environmentally relevant chemical exposures, it is necessary to investigate the combined effects of physical (e.g., suspended solids) and chemical stressors. One of the limitations in investigating suspended solids-chemical interactions has been the lack of an appropriate testing system. The specific objective of the current study was to develop and assess a suspended solids testing apparatus (SSTA) for studies on the combined effects of suspended solids and chemicals on aquatic invertebrates. The SSTA was designed to permit the assessment of varying suspended solids concentrations on Daphnia magna at a constant freely dissolved concentration of a compound. The system was also designed to facilitate the control of exposure variables without the need for large numbers of replicates and chemical analyses. The experiments reported here demonstrate that the SSTA is effective for assessing the combined or interactive effects of suspended solids and a chemical stressor on aquatic organisms.
Feeding the mummichog (Fundulus heteroclitus) a diet spiked with non-ortho- and mono-ortho-substituted Polychlorinated biphenyls: Accumulation and effects
Authors: Gutjahr-Gobell Ruth E , Black Dianne E , Mills Lesley J , Pruell Richard J , Taplin Bryan K , Jayaraman Saroja 
Published: March 2010

Abstract
A laboratory model was developed to predict exposure effects in the field. Accumulation of non-ortho- and mono-ortho-substituted PCBs in liver tissue and their effects on mummichogs (Fundulus heteroclitus) were investigated. An artificial diet spiked with a mixture of eight PCB congeners was fed to mummichogs in the laboratory. Ratios of the congeners were similar to those measured in livers of mummichogs indigenous to the PCB Superfund site, New Bedford Harbor, Massachusetts, USA. Nominal dietary concentrations were high (54.3 μg/g wet body weight), medium (10.9 μg/g), low (2.2 μg/g), and a control. Accumulation of PCBs was consistent with exposure; however, lower levels of congener 77 were detected in liver tissue (0.2–0.8% of total PCBs) than in the spiked diets (3.3–4.6%). Significant (p ≤ 0.05) mortality occurred in mummichogs fed high and medium doses relative to the control. Mortality was higher and growth was lower with increasing toxic equivalent concentration of dietary PCB concentration and accumulation of PCBs in liver tissue. Mummichogs exhibited an exposure response in congener accumulation and biological effects with increasing dietary PCB concentration. Unlike fish from New Bedford Harbor, clean fish exposed to PCBs appear to have either slower uptake or higher metabolism of congener 77, indicating possible adaptation of mummichogs inhabiting polluted environments.
Bird response to grit and pesticide granule characteristics: Implications for risk assessment and risk reduction
Authors: Stafford Tamara R , Best Louis B 
Published: March 2010

Abstract
Granular pesticides (insecticides and nematicides) pose a hazard for birds because of the potential for birds to ingest the granules. Avian risk from granular pesticides is currently assessed by using a U.S. Environmental Protection Agency risk index based on the acute toxicity of the pesticide, the pesticide concentration on the granules, and the number of granules available on the soil surface after application (LD50/ft2). Recent evaluations have demonstrated that avian response to pesticide granules as a source of grit also can influence exposure to pesticide granules; such information should be included in the risk assessment process. Herein we review the limitations of the current risk assessment process and summarize the extant information regarding bird response to grit and granule characteristics (i.e., granule carrier type, color, size, shape, and surface texture) and pesticide load per granule. Suggestions are made for assessing and reducing avian risk from granular pesticides by testing granular formulations against standards for various granule characteristics and by using frequency distributions of avian responses to granules. Granule characteristics selected as standards should be similar to grit used by free-ranging birds (e.g., silica particles, earth-tone hues). Comparisons of granular formulations against the standards would demonstrate the potential for birds to consume pesticide granules as grit, relative to naturally occurring particles. Frequency distributions constructed for grit sizes used by birds and gizzard grit counts can be used to estimate the effect of granule size and pesticide load per granule, respectively, on avian risk. Because bird response to pesticide granules is highly variable, we recommend using probabilistic approaches when assessing avian risk from pesticide granules to account for the ranges of response.
Mercury contamination in free-ranging great egret nestlings (Ardea albus) from Southern Florida, USA
Authors: Sepúlveda María S , Frederick Peter C , Spalding Marilyn G , Williams Gary E 
Published: March 2010

Abstract
Between March and June of 1994 and 1995, mercury (Hg) concentrations were determined from 393 blood and 164 growing scapular feathers from 252 great egret nestlings (Ardea albus). Nestlings came from eight colonies located in Water Conservation Area 3 in the Everglades region in southern Florida. The ages of these birds ranged from 1 to 44 d (bill length 1.1 to 10.2 cm). Mercury concentrations in blood and feathers of first-hatched great egret nestlings sampled during 1994 averaged 1.2 μg/g (range = 0.07–3.9) wet weight and 16 μg/g (4.5–40) dry weight, respectively. During 1995, first-hatched chicks had blood and feather Hg concentrations that averaged 0.8 μg/g (0.2–1.7) and 9.7 μg/g (2.3–26), respectively. In both years, Hg concentrations in blood and feathers were significantly correlated, and a significant correlation also was found between Hg in blood and age of the chicks. Blood and feather Hg concentrations differed significantly between years, with higher concentrations during 1994. Birds from JW1 and L67 colonies had the highest concentrations of Hg in blood and feathers. Mercury concentrations did not differ between chicks of different hatch order. Mercury in feathers of great egret nestlings from southern Florida are approximately six times higher when compared to feather Hg concentrations of nestling wading birds sampled elsewhere.
Effects of resin acids on hepatocyte pH in rainbow trout (Oncorhynchus mykiss)
Authors: Nikinmaa Mikko , Wickström Charlotta , Lilius Henrik , Isomaa Boris , Råbergh Christina 
Published: March 2010

Abstract
We investigated the effects of two resin acids, isopimaric acid and dehydroabietic acid, which are both important components of wood industry effluents, on the intracellular pH of rainbow trout (Oncorhynchus mykiss) hepatocytes. In HEPES-buffered medium, at an extracellular pH of 7.7, the intracellular pH of untreated hepatocytes was 7.84 ± 0.043 (mean ± SEM, n = 40). The major pathway for pH regulation was calcium-activated sodium/proton exchange, as indicated by the facts that the pH decreased when sodium was removed from the medium, when the cells were incubated in the medium containing 5-(N,N-methyl isobutyl)-amiloride (MIA, a potent inhibitor of the sodium/proton exchange), and when the cells were treated with a membranepermeant calcium ion chelator but not when the cells were treated with an inhibitor of the sodium-dependent anion exchanger. Exposure of hepatocytes to sublytic concentrations of isopimaric and dehydroabietic acid caused a pronounced decrease in intracellular pH, by 0.8 units during exposure to 50 μM isopimaric acid and by 0.5 pH units during exposure to 50 μM dehydroabietic acid. Resin acids decreased the intracellular pH mainly by acting as proton carriers across the cell membrane, because the decrease in pH also occurred in situations in which the activity of the sodium/proton exchange was inhibited either by removing calcium from the medium or by carrying out the experiments in sodium-free medium or in medium containing MIA.
Dechlorination of chloromethanes on iron and palladium-iron bimetallic surface in aqueous systems
Authors: Wan Chuhua , Chen Yong Hong , Wei Robert 
Published: March 2010

Abstract
Iron granules (&lt; 10 μ) (Fe°-H2O) and palladium-treated iron granules (Pd/Fe°-H2O) in contact with water have been tested as a potential means to dechlorinate chloromethanes (CCl4, CHCl3, and CH2Cl2) that are commonly generated in teaching chemistry laboratories. Palladium treatment enhanced the rate of dechlorination of CCl4 by a factor of about seven compared to the untreated Fe°-H2O, but the potential toxic effect of palladium remains a concern. Oxygen in the aqueous solution reduced the dechlorination rates of CCl4 with both Fe°-H2O and Pd/Fe°-H2O by at least a factor of three. Nevertheless, from the consideration of remediating solvent wastes, both systems appear suitable for treating CCl4 and possibly CHCl3 wastes, even in the presence of oxygen. The reactivities of the three chloromethanes toward the Fe°-H2O were vastly different. The dechlorination rate of CCl4 was by far the highest, followed by that of CHCl3, and CH2Cl2 was virtually unreactive toward the Fe°-H2O system. Dechlorination reactions of CCl4 and CHCl3 were systematically examined on both Fe°-H2O and Pd/Fe°-H2O. On the basis of the data, it appears that CCl4 is successively dechlorinated to form CH4 via the formation of partially dechlorinated intermediates. Proton transfer to various intermediates produces the chloromethanes: CHCl3, CH2Cl2, and CH3Cl. Furthermore, CH4 formation, independent of the proton-transferring reactions, appears to be selectively stimulated by palladium (Pd/Fe°-H2O).
Development of small outdoor microcosms for studying contaminant transformation rates and mechanisms under various water column conditions
Authors: Graham David W , Miles David , deNoyelles Frank , Smith Val H 
Published: March 2010

Abstract
Three outdoor microcosm treatments were developed to simulate aerobic (aerobic), thermally stratified (stratified), and anaerobic (anaerobic) water columns for assessing contaminant transformation rates under controlled, quasi-natural conditions. Twelve 3.2-m-diameter by 1.4-m-deep fiberglass tanks (11.3 m3 water volume) were used in the study, four for each treatment. The tanks were variably manipulated both physically (with internal frames and plastic layers) and chemically (with sediment trays and grass supplements) to facilitate the three environments. The manipulations successfully created three different and reproducible (both between tanks with common treatments and over time) aquatic systems for further study. The aerobic treatment produced a good simulation of a P-limited, mesotrophic water column. Alternately, both the stratified and anaerobic treatments developed eutrophic to hypereutrophic water conditions and had nutritionally balanced total nitrogen (TN) and total phosphorus (TP) levels (approximately 14:1 mg N/mg P). Mild thermal stratification was achieved in the stratified units and low-oxygen conditions were established in the anaerobic units. A trial study, using the herbicide alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], was performed to test the utility of the three microcosm designs for assessing comparative in situ contaminant transformation rates. This experiment was initiated by adding alachlor to all tanks to a final concentration of 50 μg/L. Alachlor levels and other chemical parameters were then monitored for 36 d. The estimated first-order alachlor decay coefficients and half-lives for the aerobic, stratified, and anaerobic treatments were 0.011/d (63 d), 0.024/d (29 d), and 0.020/d (35 d), respectively. Subsequent analyses showed that the highest rates of alachlor decay occurred in units with grass supplements, low DO and pH levels, and comparatively high TP levels. These results suggest that lower nutrient (i.e., low TP levels), photosynthesis-dominated aquatic systems produce lower alachlor decay rates, whereas higher nutrient, decomposition-dominated systems produce higher decay rates. This project shows that diverse physical and chemical environments can be created in small outdoor microcosms and that these systems can be used successfully to assess contaminant decay rates in natural systems.
Molt-independent growth inhibition of Daphnia magna by a vertebrate antiandrogen
Authors: Leblanc Gerald A , Mclachlan James B 
Published: March 2010

Abstract
The objective of this study was to identify specific physiologic parameters in crustaceans that are targeted by chemicals known to be antiandrogenic in vertebrates. We hypothesized that chemicals capable of binding to the vertebrate androgen receptor would also elicit toxicity to crustaceans by binding to specific steroid hormone receptors in an antagonistic manner. This hypothesis was tested by evaluating the effects of the antiandrogen cyproterone acetate on growth, molting, sexual differentiation, and reproduction of Daphnia magna. Exposure of daphnids to concentrations of cyproterone acetate appreciably below those that elicited mortality reduced growth but had no effect on molting. These concentrations of cyproterone acetate had no effect on various developmental and maturation parameters. Cyproterone acetate also reduced the number of offspring produced by parthenogenetically reproducing daphnids, but this effect appeared to be a consequence of the reduced size of the daphnids and their inability to accommodate a brood of more than approximately 10 eggs. These results indicate that the antiandrogen cyproterone acetate specifically targets a process critical to growth of daphnids that is independent of molting. Additional studies are warranted to established whether this is an endocrine-related toxicity to crustaceans that is associated with environmental antiandrogens such as some pesticide metabolites.
The effect of temperature on the potency of carbaryl for survival of tadpoles of the green frog (Rana clamitans)
Authors: Boone Michelle D , Bridges Christine M 
Published: March 2010

Abstract
This study assessed the effect of temperature on the potency of carbaryl using tadpoles of Rana clamitans. Temperature, chemical concentration, and the interaction of temperature and chemical significantly affected survival. Generally, increased temperature resulted in lower survival. This study suggests a range of temperatures realistic for a species should be used in toxicity tests.