bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of 17β-Estradiol on the gonopodial development and sexual activity of Gambusia holbrooki
Authors: Doyle Christopher J. , Lim Richard P.
Published: March 2010

Many chemicals have recently been demonstrated to possess estrogenic activity and may potentially interfere with normal sexual development. In the present study, we quantified the effects of waterborne exposure to 17β-estradiol on the gonopodial development and sexual activity of male eastern mosquitofish (Gambusia holbrooki). Juvenile males were exposed during the period of sexual maturation to nominal concentrations of 20, 100, and 500 ng/L of 17β-estradiol and a solvent control (0.00003% w/v ethanol) for 84 d under continuous-flow conditions. Following exposure, significant differences were found among the test treatments with respect to gonopodial length and degree of gonopodial elongation of the fish. Sexual activity, measured as the number of approaches and copulatory attempts made by the exposed males to nonexposed females, also significantly decreased with increasing concentrations of 17β-estradiol. Because the degree of gonopodial maturation and frequency of sexual activity are important characteristics for the reproductive success of male mosquitofish, it is suggested that these traits provide sensitive and ecologically relevant endpoints for assessing estrogenic activity under both laboratoryand field-exposure conditions.
Gene expression in Xenopus embryos after methylmercury exposure: A search for molecular biomarkers
Authors: Monetti Claudio , Vigetti Davide , Prati Mariangela , Sabbioni Enrico , Bernardini Giovanni , Gornati Rosalba
Published: March 2010

Mercury is a major issue in environmental health, as it can be biotransformed to methylmercury, accumulate into aquatic organisms, and enter the food chain. Therefore, we searched for molecular markers for methylmercury exposure comparing, by differential display, exposed Xenopus embryos to controls. We found two genes whose expression is completely inhibited by CH3HgCl, and we propose them as biomarkers of exposure. The first transcript appears to be a novel gene, with a short region similar to the human iron-sulfur subunit of succinate dehydrogenase. The second gene presents a high similarity with the human homeodomain-interacting protein kinase 3 (HIPK3), a protein that is known to be involved in the apoptotic signaling pathway. These molecular biomarkers could be used to detect very early effects of the metal; furthermore, they could be useful in understanding the molecular mechanisms of mercury toxicity.
Ecological effects of an anionic C12–15 AE-3S alkylethoxysulfate surfactant in outdoor stream mesocosms
Authors: Lizotte Richard E. , Dorn Philip B. , Steinriede R. Wade , Wong Diana C. L. , Odgers John H.
Published: March 2010

The ecological assessment of a C12–15 AE-3S linear alkylethoxysulfate (AES) anionic surfactant to invertebrates, fish, periphyton, and an aquatic macrophyte was conducted in a 30-d outdoor stream mesocosm study with five replicated concentrations and controls. Alkylethoxysulfate structural integrity and exposure concentrations were maintained during the 30-d treatment period, with average measured concentrations of 0.7, 1.27, 2.2, 4.31, and 10.18 mg/L. No effects were observed on the aquatic macrophyte Myriophyllum aquaticum at the highest concentration tested. A sevenfold increase in periphyton biomass at 10.18 mg/L was observed relative to controls primarily because of increases in density of the filamentous alga Mougeotia sp. Densities of the invertebrates Annelida (Stylaria), Amphipoda, Copepoda, Trichoptera (Hydropsychidae), Cladocera, and Diptera (Chironomidae) significantly decreased in streams treated with AES at 10.18 mg/L. Densities of drifting invertebrates were not observed to be affected at any concentration tested. Reproduction of Pimephales promelas significantly decreased at 1.27 mg/L and growth of juvenile Lepomis macrochirus was significantly affected at 4.31 mg/L. Multivariate cluster analysis and nonmetric multidimensional scaling ordination showed distinct structural effects on the invertebrate communities in the streams treated with AES at 10.18 mg/ L compared to the control and streams treated at <10.18 mg/L through the 30-d treatment. Convergence of the communities treated at 10.18 mg/L toward control communities in the ordination suggests recovery in these communities after termination of surfactant treatment. The results from this study support an ecosystem value of >2.0 mg/L, and indicate that the conservative Dutch risk assessment for AESs has at least a fivefold margin of safety.
Analysis of arsenic bioavailability in contaminated soils
Authors: Turpeinen Riina , Virta Marko , Häggblom Max M.
Published: March 2010

The bioavailable arsenic (As) content of contaminated soils was determined by joint analyses of acid-soluble, total water-soluble, and biovailable As by using a luminescent bacterial sensor, Escherichia coli MC1061(pTOO31). According to the results of this study, a significant positive correlation was found between the concentration of total water-soluble As and the bioavailability of As. However, the bioavailability of As in soil varied between sampling sites and was not equal when compared to the concentration of total water-soluble As; bioavailable As was 3 to 77% of total water-soluble As in soil. Our experiments also showed that aging and sequestration of As occurs in contaminated soils and As compounds thus become progressively less bioavailable with time. As a consequence, the bioavailability and toxicity of As should be considered when evaluating the ecological risks of contaminated soils.
Development and application of a generalized physiologically based pharmacokinetic model for multiple environmental contaminants
Authors: Cahill Thomas M. , Cousins Ian , Mackay Donald
Published: March 2010

The pharmacological disposition of four environmental contaminants resulting from acute and chronic exposure regimes is simulated using a general physiologically based pharmacological (PBPK) model. The model, which is detailed in supporting materials, is mechanistic in structure and relies on available physical-chemical partitioning and reactivity data, but experimental partitioning and absorption efficiency data can be used to refine the parameters. It is designed to complement environmental fate models, thus linking chemical emission rates with environmental and physiological behavior as part of the larger environmental risk assessment process. The model is illustratively applied to inhaled styrene and trichloroethene as well as ingested dibutyl phthalate and di(2-ethylhexyl) phthalate. The phthalate simulations include the corresponding monoester and conjugated monoester as metabolites. Tissue concentrations for each of the chemicals and metabolites are simulated for acute, occupational, and environmental exposure regimes. The same model is used for all chemicals and exposure regimes with only the physical-chemical properties, reaction rates, and exposure estimates being changed.
Effects of linear alkylbenzene sulfonates on functional diversity of microbial communities in soil
Authors: Vinther Finn P. , Mortensen Gerda K. , Elsgaard Lars
Published: March 2010

Linear alkylbenzene sulfonates (LAS) often occur in sewage sludge that is applied to agricultural soil. Here LAS may affect the microbial activity, which is an important basis for nutrient cycling. Previous studies have shown that single bacterial species and specific soil processes can be very sensitive to LAS. Here we report that two levels of LAS, 22 and 174 mg/kg dry weight soil, had little or no significant influence of the functional diversity of bacteria in a sandy soil, as tested by community-level physiological profiles. Briefly, these profiles are a characterization of the microbial communities based on the pattern of substrate utilization in 96-well microtiter plates (Biolog EcoPlates). Sandy agricultural soil was incubated in duplicate 1-L mesocosms with or without LAS, and bacteria were extracted after one, two, and four weeks. During incubation, more than 98 and 93% of LAS added to 22 and 174 mg/kg dry weight soil was degraded, respectively. The presence of LAS at 174 mg/kg dry weight caused a higher number of bacteria in the soil extracts, maximally corresponding to 2.5 times the numbers in LAS-free soil (1.8 × 107 cells/g dry wt soil) after four weeks of incubation. No inhibitory effect of LAS was observed when the substrate utilization data were analyzed for substrate richness and diversity (Shannon-Weaver indices). Principal component analysis, however, showed that the pattern of substrate utilization in soil with the highest LAS content (174 mg/kg dry wt) could be distinguished from control soil and soil with 22 mg LAS/kg dry weight. Yet the overall conclusion was that the functional diversity of the aerobic, heterotrophic bacterial community was rather insensitive to LAS.
Determination of polycyclic aromatic hydrocarbons in dungeness crabs (Cancer magister) near an aluminum smelter in Kitimat Arm, British Columbia, Canada
Authors: Eickhoff Curtis V. , He Shao-Xiong , Gobas Frank A. P. C. , Law Francis CP.
Published: March 2010

An aluminum smelter situated at the head of Kitimat Arm (BC, Canada) has discharged polycyclic aromatic hydrocarbons (PAHs) into the receiving waters since 1954. The purpose of the present study was to examine the distribution of PAHs contaminants in dungeness crabs (Cancer magister) collected in Kitimat Arm and Douglas Channel (BC, Canada) by determining the concentrations of PAHs in the hepatopancreas and muscle tissues of crabs by using gas chromatography-mass spectrometry. Crabs were collected at specific sites down the Arm from the smelter on four separate occasions over a three-year period. Hepatopancreas and muscle tissues of the crabs were analyzed for 10 of the 16 PAH priority pollutants recommended by the U.S. Environmental Protection Agency. Results of the studies showed that the crabs had detectable levels of PAHs in hepatopancreas and muscle tissues. The highest concentrations of PAHs in the tissues were found at a site near the aluminum smelter, the alleged point source of PAH discharge. The concentrations of PAH analytes were high in crabs collected close to the smelter and at lower levels in crabs collected throughout Douglas Channel. These results show that PAHs discharged by the smelter were bioavailable to the crabs. The concentration of each PAH analyte in the hepatopancreas was found to be strongly related to its water solubility. However, the PAH analyte concentrations in the hepatopancreas and muscle did not appear to correlate highly with each other.
Screening pyrene metabolites in the hemolymph of dungeness crabs (Cancer magister) with synchronous fluorescence spectrometry: Method development and application
Authors: Eickhoff Curtis V. , Gobas Frank A. P. C. , Law Francis C. P.
Published: March 2010

The present study examined the metabolic pathways of pyrene in dungeness crabs (Cancer magister) in the laboratory and the potential of using synchronous fluorescence spectrometry (SFS) to determine pyrene metabolite concentrations in the hemolymph of crabs exposed to polycyclic aromatic hydrocarbons (PAHs) in the field. Pyrene was metabolized by crabs mainly to 1-hydroxypyrene and pyrene-1-glucoside. Both pyrene metabolites could be detected by SFS in the hemolymph of crabs. A nondestructive hemolymph collection procedure was developed and used in conjunction with the SFS assay to assess the exposure of crabs to PAHs in Kitimat Arm (British Columbia, Canada). Our results showed that crabs obtained near the source of PAH contamination had the highest level of pyrene-related fluorescence in the hemolymph, whereas concentrations were lower at other sites downstream from the pollution source. In a separate study, the hepatopancreases of crabs were analyzed for parent PAHs by using gas chromatography-mass spectrometry. Pyrene-associated fluorescent responses of the hemolymph were found to correlate positively with the concentration of total PAHs in the hepatopancreas (r = 0.39, p < 0.05).
Immunosuppression in the northern leopard frog (Rana pipiens) induced by pesticide exposure
Authors: Gilbertson Mary-Kate , Haffner G. Douglas , Drouillard Ken G. , Albert Anathea , Dixon Brian
Published: March 2010

An injection study and a field study were used to investigate the hypothesis that environmental xenobiotics have the potential to alter the immune function of northern leopard frogs (Rana pipiens). Three assays, IgM-specific antibody response to keyhole limpet hemocyanin linked to dinitrophenyl (KLH-DNP), zymozan induced chemiluminescence (CL) of whole blood and the delayed-type hypersensitivity (DTH), were used to assay humoral, innate and cell-mediated immune endpoints. Sublethal doses of DDT (923 ng/g wet wt), malathion (990 ng/g wet wt), and dieldrin (50 ng/g wet wt) were used in the injection study. In all pesticide-injected groups, antibody response was dramatically suppressed, DTH reactions were enhanced, and respiratory burst was lower. When the order of administration of pesticides and antigens was reversed, no differences in immune function between the control and dosed groups were apparent, indicating that frogs exposed to pathogens prior to pesticide exposure can still respond. A field study found significant differences in immune function between frog populations in pesticide-exposed and pesticide-free locations. The antibody response and CL were suppressed and the DTH enhanced in frogs from Essex County (ON, Canada). Overall, the results suggest that exposure to these pesticides can cause both stimulatory and suppressive immune changes in adult frogs and is doing so in wild populations.
Plasma cholinesterase levels of mountain plovers (Charadrius montanus) wintering in central California, USA
Authors: Iko William M. , Archuleta Andrew S. , Knopf Fritz L.
Published: March 2010

Declines of over 60% in mountain plover (Charadrius montanus) populations over the past 30 years have made it a species of concern throughout its current range and a proposed species for listing under the U.S. Endangered Species Act. Wintering mountain plovers spend considerable time on freshly plowed agricultural fields where they may potentially be exposed to anticholinesterase pesticides. Because of the population status and wintering ecology of plovers, the objectives of our study were to use nondestructive methods to report baseline plasma cholinesterase (ChE) levels in free-ranging mountain plovers wintering in California, USA, and to assess whether sampled birds showed signs of ChE inhibition related to anticholinesterase chemical exposure. We compared plasma ChE activity for mountain plovers sampled from the Carrizo Plain (an area relatively free of anticholinesterase pesticide use) with similar measures for plovers from the Central Valley (where anticholinesterase pesticides are widely used). Analyses for ChE inhibition indicated that none of the plovers had been recently exposed to these chemicals. However, mean ChE levels of plovers from the Central Valley were significantly higher (32%) than levels reported for plovers from the Carrizo Plain. This result differs from our original assumption of higher exposure risk to mountain plovers in the Central Valley but does suggest that some effect is occurring in the ChE activity of mountain plovers wintering in California.
Bioavailability of desorption-resistant phenanthrene to the oligochaeteIlyodrilus templetoni
Authors: Lu Xiaoxia , Reible Danny D. , Fleeger John W. , Chai Yunzhou
Published: March 2010

We investigated bioavailability, as measured by the biota-sediment accumulation factor (BSAF), of reversibly sorbed and desorption-resistant phenanthrene to the deposit-feeding freshwater tubificid oligochaete Ilyodrilus templetoni. Desorption-resistant, phenanthrene-contaminated sediments were prepared by a sequential batch desorption method by washing with an iso-propanol solution. The BSAFs averaged 1.20 ± 0.32 and 0.59 ± 0.13 for reversibly sorbed phenanthrene and desorption-resistant phenanthrene, respectively, indicating a significantly reduced bioavailability of desorption-resistant phenanthrene. A generalized model assuming a linear relationship between pore-water concentration and normalized bioaccumulation described 91% of the variance for both measured and selected literature data of the BSAF. The reduced bioavailibility of desorption-resistant phenanthrene was thus well described by physical and chemical measures of partitioning between pore water and sediment.
Icon® rice seed treatment toxicity to crayfish (Procambarus clarkii) in experimental rice paddies
Authors: Biever Ronald C. , Hoberg James R. , Jacobson Brian , Dionne Emily , Sulaiman Mohammed , McCahon Peter
Published: March 2010

Outdoor pools (2.3 × 2.3 m) were used to simulate typical rice agricultural practices in Louisiana, USA, to evaluate the toxicity of ICON® (active ingredient [a.i.] fipronil) and its degradates to crayfish (Procambarus clarkii). Six paddies were planted with seed treated with ICON 6.2 FS at an exaggerated application rate of 0.05 kg a.i./ha (recommended rate, 0.042 kg a.i./ha), simulating three rice-planting scenarios. Two reference paddies were planted with untreated seed. Crayfish were exposed to tail water within 24 to 48 h after seeding, simulating standard Louisiana agricultural and water management practices. At 50 d after planting, a separate group of crayfish was caged in situ for 14 d to evaluate toxicity. An additional 50 crayfish were added to two paddies approximately 100 d after rice planting and held for 29 weeks to evaluate bioaccumulation. Residues of fipronil and its degradates in water and soil were similar to residue concentrations measured from rice fields in Louisiana. Tail water from the treated paddies was not toxic to crayfish. The fipronil 96-h median lethal concentration (LC50) for adult crayfish was 180 μg/L, which would provide at least a sixfold safety factor between the maximum fipronil concentration in tail water and the crayfish LC50. In situ exposures of crayfish also were not toxic. Concentrations of fipronil and its degradates after 29 weeks of exposure were less than 5 μg/kg in crayfish tail muscle tissue. These results demonstrate that label instructions adequately protect crayfish in a rice-crayfish cropping scenario when ICON is applied at maximum application rates as a seed treatment.
Bioconcentration and tissue distribution of perfluorinated acids in rainbow trout (Oncorhynchus mykiss)
Authors: Martin Jonathan W. , Mabury Scott A. , Solomon Keith R. , Muir Derek C. G.
Published: March 2010

Rainbow trout (Oncorhynchus mykiss) were exposed simultaneously to a homologous series of perfluoroalkyl carboxylates and sulfonates in a flow-through system to determine compound-specific tissue distribution and bioconcentration parameters for perfluorinated acids (PFAs). In general, PFAs accumulated to the greatest extent in blood > kidney > liver > gall bladder. Carboxylates and sulfonates with perfluoroalkyl chain lengths shorter than seven and six carbons, respectively, could not be detected in most tissues and were considered to have insignificant bioconcentration factors (BCFs). For detectable PFAs, carcass BCFs increased with increasing length of the perfluoroalkyl chain, ranging from 4.0 to 23,000, based on wet weight concentrations. Carboxylate carcass BCFs increased by a factor of eight for each additional carbon in the perfluoroalkyl chain between 8 and 12 carbons, but this relationship deviated from linearity for the longest PFA tested, possibly because of decreased gill permeability. In general, half-lives (3.9–28 d) and uptake rates (0.053–1,700 L/kg/d) also increased with increasing length of the perfluoroalkyl chain in all tissues. Sulfonates had greater BCFs, half-lives, and rates of uptake than the corresponding carboxylate of equal perfluoroalkyl chain length, indicating that hydrophobicity, as predicted by the critical micelle concentration, is not the only determinant of PFA bioaccumulation potential and that the acid function must be considered.
Effects of pulp and paper mill effluents on reproductive success of largemouth bass
Authors: Sepúlveda Maria S. , Quinn Brian P. , Denslow Nancy D. , Holm Stewart E. , Gross Timothy S.
Published: March 2010

This study evaluated the effects of bleached and unbleached kraft mill effluent on reproductive success of largemouth bass (Micropterus salmoides). Bass were exposed to effluent concentrations (0, 10, 20, 40, or 80%) for 28 and 56 d. Parameters measured included hepatosomatic index (HSI) and gonadosomatic index (GSI) and plasma concentrations of 17β-estradiol (E2), 11-ketotestosterone (11-KT), and vitellogenin (VTG). At the end of the 56-d period, bass were moved to hatchery ponds to evaluate spawning success. Spawning mats with eggs either were brought indoors for evaluation of fecundities, hatchabilities, and egg and fry size (measured at age 3 d), or were left in ponds and fry number and size recorded (average age of 14 d). Effluent exposure was verified by measuring resin acids (isopimaric, abietic, and dehydroabietic acids) in bile. Compared to controls, exposed bass had greater concentrations of resin acids in bile. In general, exposed females had lower concentrations of E2 and VTG (≥20% effluent), whereas males had lower concentrations of 11-KT (≥20% effluent) and increased E2 (≥20% effluent). The HSI values increased in females (≥10% effluent), and GSI values decreased in both sexes (≥40% effluent). Fecundity, egg size, and hatchability did not differ across treatments, but an increase in the frequency of fry abnormalities and a decrease in fry weights was observed at effluent exposures of 40% and higher. However, results from the pond study, revealed a significant reduction in fry growth and survival (≥10%). This decline may have been caused by an increased frequency of deformities, in conjunction with alterations of growth. These changes could have resulted from alterations in egg quality because of failure of parental reproductive systems, from acute embryo toxicity after translocation of contaminants from the mother to the developing embryo, or from both.
Pyrene biotransformation products as biomarkers of polycyclic aromatic hydrocarbon exposure in terrestrial isopoda: Concentration-response relationship, and field study in a contaminated forest
Authors: Stroomberg Gerard J. , Ariese Freek , van Gestel Cornelis A. M. , van Hattum Bert , Velthorst Nel H. , van Straalen Nico M.
Published: March 2010

In this study, biotransformation products of pyrene were measured in the hepatopancreas of terrestrial isopods as biomarkers of polycyclic aromatic hydrocarbon (PAH) exposure. These products—pyrene-1-glucoside, pyrene-1-sulfate, an unknown pyrene conjugate, and 1-hydroxypyrene—were quantitated using high-performance liquid chromatography (HPLC) with fluorescence detection. In a controlled exposure experiment, a linear relationship was established between pyrene exposure and pyrene metabolite concentrations in the hepatopancreas of Porcellio scaber Latr. To this end, isopods of the species P. scaber were exposed to a range of pyrene concentrations spiked to their food. A linear response was found for all pyrene conjugates in the range 0.67 to 67 μg/g of pyrene (dry wt). Hepatopancreatic pyrene metabolite concentrations were also measured in isopods (P. scaber and Oniscus asellus L.) from PAH-contaminated field sites. The sites and the inhabiting isopods were located in a gradient of atmospheric PAH deposition caused by a nearby blast furnace plant. The highest levels of conjugated 1-hydroxypyrene in the hepatopancreas were 3.8 pmol/g fresh weight (pyrene-1-glucoside) and 2.8 pmol/g fresh weight (pyrene-1-sulfate) (expressed on whole-body basis). The levels of the pyrene metabolites correlate with reported pyrene concentrations in spite of these sites. As pyrene is one of the most predominant PAHs, analysis of its metabolites provides a good tool for environmental risk assessment of ecosystems with regard to PAH exposure, bioavailability, and biotransformation.
Specific responses of bacterial cells to dioxins
Authors: Min Jiho , Pham Chi Hoa , Gu Man Bock
Published: March 2010

Five different recombinant bioluminescent strains of Escherichia coli that contain the recA (responsive to DNA damage related stress), fabA (membrane damage), katG (oxidative damage), grpE (protein damage), and lac (constitutive expression, general toxicity) promoters fused to the bacterial lux operon from either Vibrio fischeri or Photorhabdus luminescens were used to describe the different mechanisms of toxicity that several dibenzo-p-dioxins and dibenzofurans have on bacteria, as well as to determine whether bacteria can sensitively detect the presence of these compounds. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) was found to cause only DNA-related damage to bacterial cells. However, the four stress-responsive strains showed positive responses after addition of l,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD), whereas 2,3,7,8-tetrachlorodibenzo-p-furan (2,3,7,8-TCDF) caused only DNA, oxidative, and protein damage. However, 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD) was not found to induce any stresses tested for in this study, that is, DNA, membrane, oxidative, and protein damage, indicating that each congener might differentially interact with the cell, stimulating differential stress responses within them. By using the constitutive strain, we found that the level of cellular toxicity experienced due to the addition of these four dioxins decreased in the order of 2,3,7,8-TCDD (the most toxic), 1,2,3,4-TCDD, 2,8-DCDD, and 2,3,7,8-TCDF. The 20% effective concentration (EC20), defined in this study the concentration of chemical that causes a 20% decrease in the bioluminescence 60 min after induction, was only 0.1 μg/L for 2,3,7,8-TCDD, a value that is lower than that of the other congeners and demonstrates that 2,3,7,8-TCDD was the most toxic compound tested in this study.
Toxicity of lead in aqueous medium to Desulfovibrio desulfuricans G20
Authors: Sani Rajesh K. , Peyton Brent M. , Jandhyala Malathi
Published: March 2010

The toxicity of Pb(II) to sulfate-reducing bacteria (SRB) was studied using Desulfovibrio desulfuricans G20 in a medium specifically designed to assess metal toxicity. The effects of Pb(II) toxicity were observed in terms of longer lag times, lower specific growth rates, and in some cases no measurable growth. With an increase in medium pH from 6 to 8, Pb(II) toxicity decreased. At all pH values, in the presence of Pb(II) concentrations ranging from 3 to 15 μM, specific growth rates decreased and lag times increased. The minimum inhibiting concentration (MIC) of Pb(II) causing a complete inhibition in growth at pH 6 was 10 μM, as compared to 15 μM at pH 7.2 and 8. These MIC values are 40 times lower than previously reported for SRB. Results also show that with increases in initial cell protein concentration (inoculum size), soluble Pb(II) removal rates increased and the degree to which Pb(II) caused increased lag times was reduced. In the presence of Pb(II), in all cases in which D. desulfuricans grew (even after a 312-h lag time), the final cell protein concentration was equivalent to that of the Pb-free control. Live/dead staining, based on membrane integrity, indicated that while Pb(II) inhibited growth, Pb(II) did not cause a loss of D. desulfuricans membrane integrity.
Abiotic transformation of chlorpyrifos to chlorpyrifos oxon in chlorinated water
Authors: Wu Jigang , Laird David A.
Published: March 2010

In vivo transformation of chlorpyrifos to chlorpyrifos oxon is believed to be a prerequisite for this insecticide to display acute toxicity to organisms. We discovered that active chlorine dispersed in water causes the rapid abiotic transformation of chlorpyrifos to chlorpyrifos oxon. The proposed mechanism for the transformation is an electrophilic attack by hypochlorous acid (HOCl) on the thion (P=S) double bond of chlorpyrifos followed by desulfuration of chlorpyrifos to its oxon analog. The pH of a Cl-aqueous solution controls the speciation of HOCl and hypochlorite (OCl−) in water and thereby influences the transformation process. Chlorpyrifos oxon is a potent anticholinesterase that is about 1,000 times more toxic than chlorpyrifos. Because chlorination is commonly used for treatment of domestic water supplies, the findings raise a new concern about the safety of domestic use of chlorpyrifos products.
Quantitative structure-biodegradation relationship study for biodegradation rates of substituted benzenes by river bacteria
Authors: Lu Guang H. , Wang Chao , Bao Guo Z.
Published: March 2010

The biodegradation rate constant (K) of 21 substituted phenols, anilines, and benzoic acids was determined by using bacteria from the Songhua River (Jilin Province, China) as an inoculum. All of the compounds studied are readily biodegradable chemicals, as shown by their high K values. The quantitative structure-biodegradation relationship results showed that the biodegradation rate of the studied compounds is related mainly to the heat of formation (Hf) and the negative logarithm of the ionization constant (pKa), whereas no simple relationship exists with the n-octanol-water partition coefficients. The equation K = −1.127 × 10−3Hf -0.0388pKa + 0.859 was found to fit well (r2(adj) = 0.805), and the correlation coefficient between the predicted and the experimental K values was up to 0.908.
Evaluating reptile exposure to cholinesterase-inhibiting agrochemicals by serum butyrylcholinesterase activity
Authors: Sanchez-Hernandez Juan C.
Published: March 2010

Blood samples from lizards (Gallotia galloti) collected from two agricultural areas (Las Galletas and Punta del Hidalgo) and two reference areas on the Island of Tenerife (Canary Islands, Spain) were analyzed for butyrylcholinesterase (BChE) activity. Serum BChE activity was characterized first by in vitro experiments using selective substrates and inhibitors. Of the total cholinesterase (ChE) activity, 74% could be attributed to BChE activity. This portion of the total ChE activity was inhibited dose dependently by tetraisopropyl pyrophosphoramide and hydrolyzed the substrate butyrylthiocholine iodide. No enzyme inhibition was observed at high substrate concentration. Twenty-one lizards collected from agricultural sampling sites showed significant inhibition (p < 0.001) of BChE activity (mean ± standard deviation [SD] of 4.66 ± 2.63 μmol/min/ml for lizards from Las Galletas and 5.13 ± 1.48 for lizards from Punta del Hidalgo) compared with BChE activity for lizards from the reference sites (6.35 ± 1.75 μmol/min/ml). Las Galletas had the highest number of lizards (22%) with significantly inhibited BChE activity. In vitro assays showed that 10−4 M pyridine-2-aldoxime methochloride (2-PAM) reactivated dichlorvos- or paraoxon-inhibited BChE activity within a 60-min incubation period. Almost all serum samples with depressed BChE activity that were collected from lizards from agricultural areas responded to 2-PAM reactivation of enzyme activity (8–60% increase in enzyme activity). Reactivation by treatment with 2-PAM confirmed that the depression of BChE activity was attributable to organophosphorus (OP) compounds. Evaluation of BChE activity levels and the chemical reactivation of serum BChE activity in G. galloti using 2-PAM was found to be a sensitive indicator of G. galloti exposure to OP compounds.
Responses to selection for cadmium resistance in the least killifish, Heterandria formosa
Authors: Xie Lingtian , Klerks Paul L.
Published: March 2010

An artificial selection experiment was conducted for six generations to investigate the responses to selection for cadmium resistance in the least killifish, Heterandria formosa. There was a rapid response to selection. After only one generation of selection, two of the three selection lines had an increased resistance to cadmium, while all three selection lines had an elevated resistance by the next generation. After six generations of selection, fish from the selection lines survived about three times as long as control line fish when exposed to cadmium. Realized heritability for cadmium resistance was estimated to be 0.50. Cross-resistance to copper was studied in the F2, F3, and F6 generations; fish from the cadmium-resistant lines had a longer survival time than those from the control lines. Resistance to heat was investigated in the F2, F3, and F5 generations; the cadmium-resistant lines had a significantly shorter survival time than the control lines. Our results showed that evolution of resistance to cadmium was rapid, that cross-resistance to copper occurred, and that the evolution of resistance to cadmium was accompanied by a trade-off (fitness costs) as evidenced by the reduced heat tolerance.
Factors influencing the design of bioaccumulation factor and biota-sediment accumulation factor field studies
Authors: Burkhard Lawrence P.
Published: March 2010

A series of modeling simulations was performed to evaluate the underlying factors and principles that drive the uncertainty in measured bioaccumulation factors (BAFs) and biota-sediment accumulation factors (BSAFs) for fish, and to determine which sampling designs minimize those uncertainties. Temporal variability of chemical concentrations in the water column, and the metabolism rate and n-octanol-water partition coefficient (Kow) for the chemical were determined to be the dominant factors that influenced the field-sampling design. Spatial variability of the chemical concentrations, food web structure, and the sediment-water column concentration quotient had a lesser importance upon the overall design. The simulations also demonstrated that collection of composite water samples in comparison to grab water samples resulted in reductions in the uncertainties associated with measured BAFs. Some illustrative sampling design structures for BAF and BSAF measurements based upon the temporal variability of chemical concentrations in the water column and the metabolism rate and Kow for the chemical were developed. These illustrative designs provided a sense of how sampling design structures, that is, the number and spacing over time of sampling events, might be influenced by differences in temporal variabilities, metabolism rates, and Kow. Although the importance of spatial variability was discounted as a major factor in the design process, sampling of water and sediment across the immediate home range of the sampled organism is required for successful measurements because poor spatial coordination of organism, water, or sediment samples will yield BAFs and BSAFs with large and unknown biases.
The effects of chronic cadmium exposure on American toad (Bufo americanus) tadpoles
Authors: James Stacy M. , Little Edward E.
Published: March 2010

American toad (Bufo americanus) tadpoles were exposed to cadmium from shortly after hatching through metamorphosis. Cadmium at 540 μg/L decreased percentage survival and metamorphosis; 5 and 54 μg/L increased growth relative to controls. Amphibians exposed to cadmium as tadpoles may be less tolerant of natural stressors in the terrestrial environment.
Dietary oral exposure to 1,3,5-trinitro-1,3,5-triazine in the northern bobwhite (Colinus virginianus)
Authors: Gogal Robert M. , Johnson Mark S. , Larsen Calvert T. , Prater Mary R. , Duncan Robert B. , Ward Daniel L. , Lee Robyn B. , Salice Christopher J. , Jortner Bernard , Holladay Steven D.
Published: March 2010

The potential risk to wildlife from exposure to explosives, including 1,3,5-trinitro-1,3,5-triazine (RDX), has been an issue at numerous U.S. military installations where these substances are found in soil and water. Presently, no data describing the effects of RDX exposure in avian species exist. Therefore, an acute lethal dose (ALD) and 14- and 90-d subchronic dietary exposures to RDX were evaluated in a species potentially present at many contaminated sites, i.e., the northern bobwhite (Colinus virginianus). The ALDs for females and males were 187 and 280 mg/kg, respectively. Data from the 14-d dietary trial suggested that RDX exposure inhibited food consumption, weight gain, and egg production. Dietary RDX exposure for 90-d produced a dose-dependant decreasing trend in total feed consumption, total egg production, and hen-housed production parameters. These collective data suggest that quail may respond differently to oral RDX exposure compared with mammals.
Comparison of metal accumulation in mussels at different local and global scales
Authors: Blackmore Graham , Wang Wen-Xiong
Published: March 2010

Cadmium and zinc uptake from the dissolved phase, assimilation efficiency (AE) from the dietary phase, and body burden as well as clearance rate were measured in green mussels, Perna viridis, and blue mussels Mytilus edulis, M. galloprovincialis and Mytilus trossulus. Perna viridis was collected from four sites differentially enriched with trace metals in Hong Kong and blue mussels were collected from different climatic zones, i.e., subarctic and temperate, to allow comparisons with the more tropical green mussels. Despite similar shell length, the dry weight of mussels varied significantly between sites and species and this had a large effect on Cd and Zn accumulation, clearance rate, and metal body burden. All data were, therefore, weight adjusted to allow comparison without this confounding factor. Trace-metal body concentrations were significantly different between sites, and P. viridis collected from Tsing Yi, Hong Kong, had the highest levels of all measured metals when compared with other Hong Kong sites. There was, however, no relationship between the degree of metal enrichment and the Cd and Zn uptake (both from dissolved and particulate sources) and clearance rates. Furthermore, Cd and Zn uptake (dissolved and particulate) and clearance rate varied little between species or climatic zones of collection. Thus, over the range of body trace-metal concentrations measured and between mussel species over large geographical distances and climatic zones, the uptake rates, AEs, and clearance rates are similar when measured under the same laboratory conditions after body-size correction. When other factors such as salinity are also corrected, biomonitoring data from different areas and even utilizing different mussel species may be directly comparable. This study therefore provides important evidence in support of Mussel Watch Programs.
Disturbances to metal partitioning during toxicity testing of iron(II)-rich estuarine pore waters and whole sediments
Authors: Simpson Stuart L. , Batley Graeme E.
Published: March 2010

Metal partitioning is altered when suboxic estuarine sediments containing Fe(II)-rich pore waters are disturbed during collection, preparation, and toxicity testing. Experiments with model Fe(II)-rich pore waters demonstrated the rates at which adsorptive losses of Cd, Cu, Ni, Mn, Pb, and Zn occur upon exposure to air. Experiments with Zn-contaminated estuarine sediments demonstrated large and often unpredictable changes to metal partitioning during sediment storage, removal of organisms, and homogenization before testing. Small modifications to conditions, such as aeration of overlying waters, caused large changes to the metal partitioning. Disturbances caused by sediment collection required many weeks for reestablishment of equilibrium. Bioturbation by benthic organisms led to oxidation of pore-water Fe(II) and lower Zn fluxes because of the formation of Fe hydroxide precipitates that adsorb pore-water Zn. For five weeks after the addition of organisms to sediments, Zn fluxes increased slowly as the organisms established themselves in the sediments, indicating that the establishment of equilibrium was not rapid. The results are discussed in terms of the dynamic nature of suboxic, Fe(II)-rich estuarine sediments, how organisms perturb their environment, and the importance of understanding chemistry in toxicity testing with whole sediments or pore water. Recommendations are provided for the handling of sediments for toxicity testing.
Sublethal energetic responses byPisidium amnicum(Bivalvia) exposed to pentachlorophenol at two temperatures
Authors: Heinonen Jari , Penttinen Olli-Pekka , Holopainen Ismo J. , Kukkonen Jussi V. K.
Published: March 2010

Sublethal effects of pentachlorophenol (PCP) were studied in the freshwater clam Pisidium amnicum by examining the cause-effect relationship between PCP body burden and the rate of the whole animal heat output. In addition, the modifying effects of temperature (7 and 15°C) and trematode parasites as natural stress factors were assessed. Results showed that even a low PCP body burden was sufficient to increase the heat output during the periods of aerobic metabolism and the magnitude of responses increased linearly with increasing body burden. During a valve-closure period, however, PCP had no effect on anaerobic heat output. The rise of the maximum heat output in response to PCP was more pronounced at the higher temperature. The response in heat output was similar in both infected and uninfected clams, but the general level of heat output was lower in infected clams. The increasing PCP body burden also increased the duration of valve-closure time. The results of this study suggested that microcal-orimetry could be a useful tool in assessing sublethal responses by the clam, which offers several calorimetrically measurable parameters such as aerobic and anaerobic heat output and behavior.
Adsorption, complexation, and phytoavailability of copper as influenced by organic manure
Authors: Bolan Nanthi , Adriano Domy , Mani Senniappan , Khan Afiqur
Published: March 2010

Copper (Cu) is bound strongly to clay minerals and organic matter in soils, and forms both insoluble and soluble organic complexes with organic carbon. In this experiment, the effect of five manure composts (biosolid, farmyard manure, spent mushroom, pig manure, and poultry manure) on the adsorption and complexation of Cu in a mineral soil (Manawatu sandy soil, Palmerston North, New Zealand) low in organic matter content was examined. The effect of biosolid on the uptake of Cu from the soil, treated with various levels of Cu (0–400 mg/kg soil), was examined by using mustard (Brassica juncea L.) plants. The redistribution of the added Cu in soil was evaluated by a chemical fractionation scheme. Addition of manure compost increased the adsorption and complexation of Cu by the soil. At the same level of total organic carbon addition, a significant difference was found in the extent of Cu adsorption among the manure-amended soils. However, less difference was found in the amount of Cu complexed among the manure-amended soils. A significant inverse relationship was found between the extent of Cu adsorption and the dissolved organic carbon (DOC) in the manure-amended samples, indicating that DOC formed soluble complexes with Cu. Increasing addition of Cu increased Cu concentration in plants, resulting in decreased plant growth at high levels of Cu (i.e., phytotoxicity). Addition of biosolid was found to be effective in reducing the phytotoxicity of Cu at high levels of Cu addition. Significant relationships were found between dry matter yield and total Cu or free Cu2+ concentration in soil solution. Addition of biosolid decreased the concentration of the soluble and exchangeable Cu fraction but increased the concentration of the organic-bound Cu fraction in soil.
General fugacity-based model to predict the environmental fate of multiple chemical species
Authors: Cahill Thomas M. , Cousins Ian , Mackay Donald
Published: March 2010

A general multimedia environmental fate model is presented that is capable of simulating the fate of up to four interconverting chemical species. It is an extension of the existing equilibrium criterion (EQC) fugacity model, which is limited to single-species assessments. It is suggested that multispecies chemical assessments are warranted when a degradation product of a released chemical is either more toxic or more persistent than the parent chemical or where there is cycling between species, as occurs with association, disassociation, or ionization. The model is illustratively applied to three chemicals, namely chlorpyrifos, pentachlorophenol, and perfluorooctane sulfonate, for which multispecies assessments are advisable. The model results compare favorably with field data for chlorpyrifos and pentachlorophenol, while the perfluorooctane sulfonate simulation is more speculative due to uncertainty in input parameters and the paucity of field data to validate the predictions. The model thus provides a tool for assessing the environmental fate and behavior of a group of chemicals that hitherto have not been addressed by evaluative models such as EQC.
Identification of phototransformation products of prednisone by sunlight: Toxicity of the drug and its derivatives on aquatic organisms
Authors: DellaGreca Marina , Fiorentino Antonio , Iesce Maria Rosaria , Isidori Marina , Nardelli Angela , Previtera Lucio , Temussi Fabio
Published: March 2010

Solar simulator irradiation of an aqueous suspension of prednisone, a widely prescribed drug, produces seven photochemical derivatives. The compounds have been identified on the basis of their physical features. All the chemicals have been tested to evaluate their toxic effects on freshwater organisms from different trophic levels. The rotifer Brachionus calyciflorus and two crustaceans, the cladoceran Daphnia magna and the anostracan Thamnocephalus platyurus, were used to perform acute toxicity tests. Chronic toxicity tests have been performed on the alga Pseudokirchneriella subcapitata (formerly known as Selenastrum capricornutum) and the crustacean Ceriodaphnia dubia. The results showed low acute and chronic toxicity of prednisone. Some of the photoproducts had high toxic effects on C. dubia.
Copper bioaccumulation by the freshwater snail Lymnaea peregra: A toxicological marker of environmental and human health?
Authors: Pyatt F. Brian , Metcalfe Matthew R. , Pyatt Andrea J.
Published: March 2010

Snails (Lymnaea peregra) were exposed to both low and high concentrations of copper (as copper nitrate) under controlled conditions and then were sacrificed and dissected; various tissues/organs were removed and subsequently analyzed by atomic absorption spectrophotometry to determine both the copper concentration and the nature of localization. At low concentrations, bioaccumulation was evident in various tissues/organs; a dose response occurred in tissues derived from both the head and foot. At high concentrations, the copper concentrations of the liver-like body and kidney became massively enhanced. There was some variability in the ranking of tissues/organs with regard to copper bioaccumulation—this was predominantly linked to the copper concentration to which the snails were exposed. Mechanisms of copper bioaccumulation are reviewed and comparisons with other organisms made.
Predicting sediment toxicity using logistic regression: A concentration-addition approach
Authors: Smith Eric P. , Robinson Tim , Field L. Jay , Norton Susan B.
Published: March 2010

The question posed in this article is how useful the chemical concentration measurements for predicting the outcome of sediment toxicity tests are. Using matched data on sediment toxicity and sediment chemical concentrations from a number of studies, we investigated several approaches for predicting toxicity based on multiple logistic regression with concentration-addition models. Three models were found to meet criteria for acceptability. The first model uses individual chemicals selected using stepwise selection. The second uses derived variables to reflect combined metal contamination, polycyclic aromatic hydrocarbon (PAH) contamination, and the interaction between metals and PAHs. The third and final model is a separate species model with derived variables. Overall, these models suggest that toxicity may be correctly predicted approximately 77% of the time, although prediction is better for samples identified as nontoxic than for those known to be toxic.