bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterizing aquatic ecological risks from pesticides using a diquat dibromide case study. II. Approaches using quotients and distributions
Authors: Campbell Kym Rouse , Bartell Steven M , Shaw Jennifer L
Published: March 2010

Realistic and reliable methods are needed for the accurate characterization of the potential ecological risks posed by pesticides. This study presents a sequence of risk assessment methods that are based on the comparison of exposure concentrations to laboratory-derived toxicity data for representative species of aquatic organisms exposed to pesticides. The sequence of methods progresses from single-value quotient calculations to comparison of cumulative distributions of exposure and toxicity data and culminates with the use of Monte Carlo methods to estimate distributions of quotients. To illustrate the sequence of increasingly quantitative methods, we used a case study of the ecological risks posed by diquat dibromide in U.S. regional lakes and farm ponds. Diquat dibromide is a well-studied aquatic herbicide and is one of only a few pesticides registered for direct use in aquatic systems. The exposure concentration for the farm pond scenario used in the U.S. Environmental Protection Agency reregistration eligibility decision for diquat dibromide was used. In addition, exposure concentrations were developed for several regional lake and farm pond scenarios using the Exposure Analysis Modeling System (EXAMSII) methodology with separate, region-specific parameter values and simulated diquat dibromide application rates. Except for the results obtained in the conservative quotient method, the calculations for diquat dibromide were consistent with its demonstrated high safety. This suggests that a minimal ecological impact to benthic invertebrates and fish exists. Aquatic plants in the vicinity of application to surface waters appear to be at risk, and this is expected, as diquat dibromide kills aquatic plants. Comparisons of cumulative distributions of exposure and toxicity data provided the most quantitative approach to characterizing risks. The probabilistic quotient approach does not specifically estimate ecological risk. However, the implicit correlation between increasing values of quotients and increased potential risk does suggest the utility of these methods for identifying pesticides as acceptable for registration and use (i.e., minimal risk compared to benefits) or unacceptable.
Metal toxicity inferred from algal population density, heterotrophic substrate use, and fatty acid profile in a small stream
Authors: Genter Robert B , Lehman R Michael
Published: March 2010

The purpose of this study was to examine relations between metal concentrations in periphyton and the abundance of algal species, heterotrophic use of 95 carbon sources, and phospholipid fatty acids (PLFA) of the periphyton in a small stream spanning a mine in Lemhi County, Idaho, USA. Two upstream, two mine, and two downstream sites were examined. Elevated concentrations of As and Cu at the mine sites were associated with communities that were depleted of diatoms and filamentous blue-green algae and characterized by a low-diversity community dominated by a single blue-green alga and patchy populations of the diatom Achnanthidium minutissimum and a filamentous green alga. Carbon source use and PLFA profiles provided a rapid assessment of stream conditions that were consistent with algal taxonomy and with our hypotheses constructed from previous reports on periphyton responses to metal stress.
Laboratory to field validation in an integrative assessment of an acid mine drainage–impacted watershed
Authors: Soucek David J , Cherry Donald S , Currie Rebecca J , Latimer Henry A , Trent G Claire
Published: March 2010

An integrative assessment was conducted in the Puckett's Creek watershed of southwestern Virginia, USA, to investigate the environmental impacts of acid mine drainage (AMD) inputs. Twenty-one sampling stations were categorized into groups based on five degrees of AMD input: (1) none, (2) intermittent acidic/circum-neutral AMD, (3) continuous acidic AMD, (4) continuous circum-neutral AMD, and (5) receiving system stations with at least two levels of dilution. Bioassessment techniques included water/sediment chemistry, benthic macroinvertebrate sampling, laboratory acute water column toxicity testing, laboratory chronic sediment toxicity testing, and in situ toxicity testing with Asian clams (Corbicula fluminea [Müller]). Group 3 stations had significantly altered water chemistry (low pH, high conductivity, and high water column metals) relative to the other groups and significantly higher sediment iron concentrations. Both group 3 and group 4 stations had significantly decreased ephemeroptera-plecoptera-trichoptera richness and percent ephemeroptera abundance relative to unimpacted stations. Group 3 stations also had decreased total taxon richness. Water column toxicity testing was sensitive to AMD impacts, with samples from group 3 stations being significantly more toxic than those from groups 2 and 4, which in turn were more toxic than those from groups 1 and 5. Similar results were observed for in situ toxicity testing. No differences in sediment toxicity test survival and impairment results were observed among the station groups. Stepwise multiple linear regression and simple bivariate correlation analyses were used to select parameters for use in an ecotoxicologic rating system, which was successful in differentiating between two levels of environmental impact relative to stations receiving no AMD input.
Bottom-up and top-down approaches to assess multiple stressors over large geographic areas
Authors: Dyer Scott D , White-Hull Charlotte , Carr Gregory J , Smith Eric P , Wang Xinhao
Published: March 2010

The relationship of multiple factors, such as instream habitat, drainage area, gradient, cumulative effluent, conventional pollutants, and chemical mixtures, to fish communities was explored at the subbasin, basin, and state level within the state of Ohio, USA. Two approaches were used: bottom-up, which focused on subbasin- and basin-level relationships within the Great Miami River, Ohio, and top-down, focusing on relationships across the entire state. Data were provided by the Ohio Environmental Protection Agency and the U.S. Environmental Protection Agency. These data were integrated via a geographical information system. Multiple linear regression was used to determine the strength of stressor–response relationships. The greatest amount of variation of the index of biotic integrity (IBI) and selected metrics was addressed at the subbasin level, followed by the basin and state level, respectively. Overall, habitat factors were the best predictors and positively related to the IBI and number of fish species. Chemical factors, such as cumulative effluent, metals, ammonia, and biochemical oxygen demand, were consistently observed as negative, moderating factors for IBI and fish taxa richness and were the best predictors of the percent of fish observed with deformities, fin erosions, lesions, and tumors.
Estrogen receptor- and aryl hydrocarbon receptor-mediated activities of a coal-tar creosote
Authors: Fielden Mark R , Wu Zhi-Fen , Sinal Christopher J , Jury Heather Hodgert , Bend John R , Hammond Geoffrey L , Zacharewski Tim R.
Published: March 2010

A coal-tar creosote was examined for estrogen receptor (ER)–and aryl hydrocarbon receptor (AhR)–mediated activity using a battery of mechanistically based assays. In vitro, creosote was found to bind to the mouse ER, bind to the human sex hormone–binding globulin, and elicit partial agonist activity in reporter gene assays in transiently transfected MCF-7 cells. Based on competitive binding to the mouse ER, creosote contains approximately 165 mg/L of estradiol-equivalents. Creosote effectively transformed the AhR in vitro and induced a Cyp1a1-regulated luciferase reporter gene in transiently transfected Hepa 1c1c7 cells. Based on dose–response curves, creosote contains approximately 730 mg/L of dioxin-equivalents. Creosote did not exhibit any AhR-mediated antiestrogenic activity in vitro. In vivo, creosote significantly induced liver pentoxyresorufin O-depentylation and ethoxyresorufin-O-deethylation (EROD) in a dose-dependent manner in ovariectomized (OVX) ICR mice, but did not increase uterine weight wet or vaginal cornification, due possibly to AhR-mediated antiestrogenic activity. In OVX DBA/2 mice, a strain less responsive to AhR ligands, creosote induced liver EROD to a lesser extent, but still did not show an increase in uterine wet weight or vaginal cornification. These results demonstrate that coal-tar creosote exhibits AhR- and ER-mediated activity in vitro, but its dioxinlike activity may suppress estrogenic responses in vivo.
Effects of 4-nonylphenol on fecundity and biomarkers of estrogenicity in fathead minnows (Pimephales promelas)
Authors: Giesy John P. , Pierens Susan L , Snyder Erin M , Miles-Richardson Stephanie , Kramer Vincent J , Snyder Shane A , Nichols Krista M , Villeneuve Daniel A
Published: March 2010

Aultfathead minnows (Pimophales promelas) were exposed to waterborne concentrations of 4-nonylphenol (NP) ranging from 0.05 to 3.4 μg NP/L for 42 d. Results were similar, but slightly different, for two experiments conducted during July and August, near the beginning of the breeding season, and a second experiment conducted during September and October, at the end of the breeding season, during which the adults were maintained continuously in breeding condition. Inverted U–type dose-response relationships were observed for egg production and for concentrations of vitellogenin (Vtg) and 17β-estradiol (E2) in blood plasma. Concentrations of plasma Vtg were significantly different between males and females, with plasma concentrations in females ranging from 20 to 110 μg Vtg/ml. Both experiments had no statistically significant, dose-dependent effect of NP on plasma Vtg in males but significant effects of NP on Vtg concentrations in females. In the first experiment, Vtg concentration generally increased with NP concentration, whereas the second experiment showed a negative correlation. Plasma E2 concentrations in both males and females were significantly affected by NP. The concentration of total estrogen equivalents in the plasma increased 900% because of exposure to NP. Most of this increase resulted from increased plasma E2 concentrations, with only a 4% increase resulting from the estrogen agonist activity of NP. The effects of NP on adult fathead minnows seem not to result from a direct-acting estrogen agonist mechanism but rather from changes in the endogenous concentrations of E2 through an indirect activation mechanism of action.
Some bioaccumulation factors and biota-sediment accumulation factors for polycyclic aromatic hydrocarbons in lake trout
Authors: Burkhard Lawrence P , Lukasewycz Marta T
Published: March 2010

Bioaccumulation factors (BAFs) and biota-sediment accumulation factors (BSAFs) for phenanthrene, fluoranthene, pyrene, benz[a]anthracene, and chrysene/triphenylene were calculated using the tissue data of Zabik et al. for Salvelinus namaycush siscowet with a 20.5% lipid content, the water data of Baker and Eisenreich, and the sediment data of Baker and Eisenreich for the Lake Superior ecosystem. Log BAFs, both lipid normalized and based on the freely dissolved concentration of the chemical in the water, of 1.95, 3.22, 4.72, 4.73, and 3.61 were calculated for phenanthrene, fluoranthene, pyrene, benz[a]anthracene, and chrysene/triphenylene, respectively. The BSAFs for phenanthrene, fluoranthene, pyrene, benz[a]anthracene, and chrysene/triphen-ylene were 0.00011, 0.00016, 0.0071, 0.0054, and 0.00033, respectively.
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

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

This 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 <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

Biochemical 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, <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

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

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

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

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

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 < 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

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

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

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

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

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.
Effects of atrazine and nitrate on northern leopard frog (Rana pipiens) larvae exposed in the laboratory from posthatch through metamorphosis
Authors: Allran John Wesley , Karasov William H
Published: March 2010

A ecent ecological rsk assessment of the herbicideatrazinefound that theecosystemsat greatest risk within North America are the streams, rivers, and reservoirs of the midwestern corn-growing regions. Habitats adjacent to application areas could be exposed to high levels of atrazine during periods of amphibian activity such as breeding and migration. Because fertilizer application coincides both spatially and temporally with atrazine application in agricultural areas, we tested the effects of atrazine and nitrate on northern leopard frog (Rana pipiens) larvae in the laboratory. Larvae were exposed to atrazine (0, 20, and 200 μg/L) and nitrate (0, 5, and 30 mg NO3-N/L) from first-feeding stage through metamorphosis in a factorial design. Atrazine concentrations in metamorphosed juveniles were approximately six times the concentration in the water, indicating bioconcentration of atrazine by larvae. Atrazine, nitrate, and their interaction had no significant effect on development rate, percent metamorphosis, time to metamorphosis, percent survival, mass at metamorphosis, or hematocrit. However, nitrate slowed growth of larvae. Though this growth inhibition is statistically significant, it is probably not biologically important when compared with natural variation in the environment. Thus, concentrations of atrazine and nitrate commonly found in the environment do not appear to pose a significant threat to R. pipiens larvae through direct toxicity.
Concentration dependency of biota-sediment accumulation factors for chlorinated dibenzo-p-dioxins and dibenzofurans in dungeness crab (Cancer magister) at marine pulp mill sites in British Columbia, Canada
Authors: Cretney Walter J , Yunker Mark B
Published: March 2010

Biota-sediment accumulation factors (BSAFs) for some chlorinated dibenzo- p -dioxin and dibenzofuran congeners (PCDD/Fs) in Dungeness crab (Cancer magister) hepatopancreas and associated sediments are concentration independent as required by equilibrium partition models. In particular 2, 3, 7, 8-tetrachlorodibenzo-p -dioxin (2, 3, 7, 8-TCDD), 2, 3, 7, 8-tetrachlorodibenzofuran, the 2, 3, 7, 8-substituted pentachlorodibenzofurans, and the non-2, 3, 7, 8-hexachlorodibenzofurans (HxCDFs) seem to fall into this group. The BSAFs for other isomers exhibit significant, nonlinear variations with sediment or crab PCDD/F concentrations. For some of these other isomers (e.g., the non-2, 3, 7, 8 TCDDs and possibility the 2, 3, 7, 8-substituted HxCDFs), association of a variable fraction of the total present with soot carbon may provide a satisfactory explanation for the concentration behavior. For the HxCDDs we propose that the nonlinear concentration behavior may arise from the thermodynamic properties of fluids confined in hydrophobic voids within particulate and colloidal material produced by the pulp mills. The nonlinear relationship between BSAFs and PCDD/F concentrations greatly complicates prediction of the potential for dioxin and furan bioaccumulation in crabs and the formulation of sediment quality criteria. We provide a nonlinear equation relating toxic equivalency and sediment concentrations.
Simulation study of characteristics of statistical estimators of inhibition concentration
Authors: Bailer A John , Elmore Ryan T , Shumate B Joseph , Oris James T
Published: March 2010

Statistical estimators of the concentrations associated with specified levels of reproductive toxicity in the aquatic organism Ceriodaphnia dubia are presented and compared. The first estimator, the ICp or inhibition concentration approach, was based on a nonparametric estimation routine that assumed responses monotonically declined with increasing concentrations. This estimator also assumed that linear interpolation between mean responses associated with consecutive concentration groups was reasonable. The second estimator, the RIp or reproductive inhibition concentration approach, was based on a parametric concentration-response model. This model assumed that the number of young is a Poisson or negative, binomially distributed, random variable, and that the mean number of young could be modeled using an exponential term involving a polynomial in the test concentrations. Confidence intervals for both these estimators were obtained using variants of a bootstrap resampling procedure. The properties of these estimators, namely bias, mean squared error, and coverage probabilities, were compared in a Monte Carlo simulation study. The results from this study suggested that over a broad range of realistic conditions, the confidence intervals associated with the ICp estimator failed to maintain nominal coverage probabilities, whereas the confidence intervals associated with the RIp estimator performed as nominally stated under most conditions. Finally, correct specification of the model concentration-response pattern was observed to be important for estimating inhibition concentrations with small bias and variability.
Innovative techniques for harmful algal toxin analysis
Authors: Pierce Richard H , Kirkpatrick Gary J
Published: March 2010

The global increase in frequency and intensity of harmful algal blooms (HABs) has led to more frequent incidence of seafood-borne illnesses and adverse impacts on natural resources. In response, public health agencies worldwide have mobilized to initiate HAB monitoring programs. To meet this demand, innovative analytical techniques are being developed that provide rapid and reliable detection of the causative organisms and the toxins produced. Modifications to conventional chromatography and mass spectrometry have greatly improved sensitivity and selectivity of these methods toward naturally occurring phycotoxins. Bioassay techniques using live organisms are giving way to molecular and cellular methods that measure the toxicologically significant activity of the toxin molecules. Molecular probes are being applied to distinguish species-specific RNA and DNA sequences for rapid identification of HAB-causing organisms. The direction of this new technology is to develop rapid and reliable screening methods for phycotoxins and the causative organisms to provide protection for public health, aquaculture, and natural resources. New methods also are being developed for detecting minute amounts of toxin molecules in microenvironments, leading to understanding the toxicokinetics and toxicological functions of the toxins.
Immunohistochemical localization of cytochrome P4501A induced by 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126) in multiple organs of northern leopard frogs,Rana pipiens
Authors: Huang Yue-Wern , Stegeman John J , Woodin Bruce R , Karasov William H
Published: March 2010

Monoclonal antibody 1 12–3(MA1 12–3)recognizesanepitopeexclusivetocytochromeP450sinsubfamily1A (CYP1A) from all vertebrates tested so far, including one amphibian species. In this study, we first tested the utility of MAb 1–12-3 for detection of presumed CYP1A proteins in hepatic microsomes of northern leopard frogs treated without or with 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126). Statistical analysis showed that ethoxyresorufin-O-deethylase (EROD) activities and CYP1A equivalents in treated groups were significantly increased at doses >2.3 mg/kg compared with the control groups (p < 0.05), and the increases were maintained for at least four weeks. This result confirmed that MAb 1–12-3 can be used for detection of CYP1A in northern leopard frogs and indicated that CYP1A is the primary catalyst for EROD in this species. In a subsequent experiment, sections of organs of PCB 126-treated frogs were immunohistochemically stained with MAb 1–12-3 to identify localization of the CYP1A in different cell types. The CYP1A staining was seen prominently in hepatocytes and epithelium of nephronic duct, while capillaries close to gastric epithelium and submucosal vascular epithelium in both stomach and intestine exhibited moderate to strong staining. The CYP1A was immunodetected in coronary endothelium and the vascular endothelium of lung and gonad. In skin, mild staining was seen in epithelial cells of mucous glands and serous glands and in vascular endothelium, demonstrating induction of CYP1A in the dermal layer.
Biological response to variation of acid-volatile sulfides and metals in field-exposed spiked sediments
Authors: Boothman Warren S , Hansen David J , Berry Walter J , Robson Deborah L , Helmstetter Andrea , Corbin Jeffrey M , Pratt Sheldon D
Published: March 2010

Vertical and temporal variations of acid-volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediment can control biological impacts of metals. To assess the significance of these variations in field sediments, sediments spiked with cadmium, copper, lead, nickel, and zinc were deployed in Narragansett Bay for four months and recolonization by benthic organisms investigated. In surface sediments, concentrations of AVS decreased with time whenever AVS exceeded SEM but remained unchanged when AVS was less than SEM; in subsurface sediments, concentrations increased slightly. Concentrations of total SEM decreased with time only in surface sediments in which SEM exceeded AVS. Metals were not detected in interstitial waters of sediments where AVS exceeded SEM but were significant when SEM exceeded AVS and followed the order of solubilities of their sulfides. Concentrations in interstitial waters decreased with time, but exceeded U.S. Environmental Protection Agency chronic water quality criteria for 56 to 119 d. After 119 d, faunal assemblages in all treatments were similar to controls. Lack of biological response was related to vertical distributions of AVS and SEM. Biological exposure took place in near-surface sediments, where AVS exceeded SEM in even the highest treatments. Therefore, concentrations of metals in interstitial waters were low and consequently biological impacts were undetectable.
Uptake of polycyclic aromatic hydrocarbon compounds by the gills of the bivalve mollusk Elliptio complanata
Authors: Birdsall Karen , Kukor Jerome J , Cheney Marcos A
Published: March 2010

Polycyclic aromatic hydrocarbons (PAHs) and herbicides are important contaminants of world water systems with effects on aquatic organisms. The uptake of naphthalene, anthracene, and chrysene by gills of the bivalve mollusk Elliptio complanata was determined. Additionally, the effects of paraquat, atrazine, alachlor, 2,4-dichlorophenoxyacetic acid (2,4-D), and 2,4-dinitrophenol on the uptake of these compounds were also determined. The results indicate (1) the uptake of anthracene is approximately equivalent to that of chrysene and the uptake of either of these compounds is higher than that of naphthalene; (2) comparisons of uptakes with that of inulin, which occupies only extracellular space, show that all compounds studied are taken up; (3) the uptakes of naphthalene, anthracene, and chrysene are initially altered by the presence of herbicides such as paraquat, alachlor, 2,4-D, atrazine, and 2,4-dinitrophenol.
Characterization of the acute toxicity of photoactivated fluoranthene to glochidia of the freshwater mussel,Utterbackia imbecillis
Authors: Weinstein John E
Published: March 2010

The acute photoactivated toxicity of fluoranthene to the glochidial larvae of the paper pondshell, Utterbackia imbecillis, was characterized in the laboratory using three sets of experiments. Toxicokinetic studies revealed that glochidia rapidly bioaccumulated fluoranthene, reaching an apparent steady state in 4 h. Based on a two-compartment model, uptake (Ku) and depuration (Kd) rate constants were 1394 ml/g/h and 0.769/h, respectively. However, experimental data suggested the presence of a fast and slow depuration compartment with a Kd of 0.290 and 0.031/h, respectively. Replicate 24-h acute toxicity tests designed to determine the overall sensitivity of glochidia to photoactivated fluoranthene were conducted under simulated sunlight (ultraviolet [UV]-A = 69.0 ±1.0 μW/cm2) (mean ± standard deviation [SD]). Mean median lethal concentrations (LC50) of fluoranthene at 8, 16, and 24 h were 5.59 ± 0.59, 4.09 ± 0.57, and 2.45 ± 0.45 μg/L, respectively. Mean median lethal doses (LD50) at the same time periods were 14.76 ± 2.17, 11.66 ± 2.82, and 6.98 ± 1.31 μg/g dry weight, respectively. Acute toxicity tests designed to elucidate the relationship between the rate of mortality and UV intensity were conducted under one of four different UV intensities (UV-A = 15, 31, 50, and 68 μW/cm2). Regression analysis revealed that the time-dependent mortality of glochidia was inversely related to the product of initial tissue residue of fluoranthene and UV intensity. These findings suggest that glochidia of freshwater mussels are among the most sensitive organisms tested to date to photoactivated fluoranthene and the time-dependent mortality of glochidia can accurately be predicted through evaluation of the product of fluoranthene tissue residue and the light intensity to which the glochidia is exposed.
Enhanced mineralization of benzo[a]pyrene in the presence of nonaqueous phase liquids
Authors: Kanaly Robert A. , Bartha Richard , Watanabe Kazuya , Harayama Shigeaki
Published: March 2010

Bacterial mineralization of [7- 14C]benzo[a]pyrene (BaP) to 14CO2 was enhanced by the presence of nonaqueous phase liquids (NAPLs). Mineralization of BaP was affected differently by different NAPLs, and the mode of enhancement of mineralization by a NAPL most likely occurred by a combination of cometabolic and physical effects. Mineralization was enhanced to the greatest extent when BaP was dissolved in a high-boiling distillation product of diesel fuel.