bluuebunny/crossref_metadata_2025 huggingface dataset:
Methylsulfone polycglorinated biphenyl and 2,2-bis(chlorophenyl)-1,1-dichloroethylene metabolites in beluga whale (Delphinapterus leucas) from the St. Lawrence river estuary and western Hudson bay, Canada
Authors: Letcher Robert J. , Norstrom Ross J , Muir Derek CG , Sandau Courtney D , Koczanski Krystyna , Michaud Robert , De Guise Sylvian , Béland Pierre
Published: March 2010

Kowledge is limited regarding methylsulfone (MeSO2)-polychlorinated biphenyl (PCB), and especially MeSO2–2,2-bis(chlorophenyl)-1,1-dichloroethylene (DDE), metabolites in cetacean species. We hypothesized that the ability of beluga whale (Delphinapterus leucas) to biotransform PCB and DDE compounds, and to form and degrade their MeSO2 PCB and -DDE metabolites, is related to the capacity for xenobiotic metabolism. Adipose biopsies were collected from male and female beluga whale from distinct populations in the St. Lawrence River estuary (STL) and western Hudson Bay (WHB), Canada, which are contrasted by the exposure to different levels of cytochrome P450 enzyme-inducing, chlorinated hydrocarbon contaminants. The PCBs, DDTs, DDEs, 28 MeSO2 metabolites of 14 meta-para chlorine-unsubstituted PCBs, and four MeSO2 metabolites of 4,4′- and 2,4′-DDE were determined. The mean concentrations of total (Σ-) MeSO2-PCB in male STL beluga (230 ng/g), and ratios of Σ-MeSO2-PCB to Σ-PCB (0.05) and Σ-precursor-PCB (0.17) were approximately twofold higher, whereas the Σ-precursor-PCB to Σ-PCB ratio was approximately twofold lower, than in male WHB beluga. Both populations had a low formation capacity for MeSO2-PCBs with ≥six chlorines (<4% of Σ-MeSO2-PCBs). The congener patterns were dominated by trichloro- and tetrachloro-MeSO2-PCBs, and tetrachloro- and pentachloro-MeSO2-PCBs in WHB and STL animals, respectively. In addition to 2- and 3-MeSO2-4,4′-DDE, two unknown MeSO2-2,4′-DDEs were detected. The mean 3-MeSO2-4,4′-DDE concentration in STL beluga (1.2 ng/g) was much greater than in WHB (<0.01 ng/g) animals. The concentrations of 4,4′-DDE, and not 3-MeSO2-4,4′-DDE, increased with age in male STL animals. We demonstrated that sulfone formation and clearance is related to metabolic capacity, and thus PCB, DDE, and MeSO2-PCB and -DDE toxicokinetics differ for STL and WHB beluga. In the past, the capacity of odontocetes for PCB and DDE biotransformation leading to persistent sulfone metabolites has been underestimated. More information is needed for other cetacean species and marine mammals. The results of this study indicate that MeSO2-PCBs and -DDEs need to be included in the toxicologic risk assessment of PCB and DDT exposure in odontocetes, and perhaps for cetaceans in general.
Transformation of 2,4,6-trinitrotoluene in soil in the presence of the earthworm Eisenia andrei
Authors: Renoux Agnès Y. , Sarrazin Manon , Hawari Jalal , Sunahara Geoffrey I
Published: March 2010

The ability of the earthworm Eisenia andrei to metabolize 2,4,6-trinitrotoluene (TNT) was studied in experiments with TNT-spiked soils, dermal contact tests, and with an in vitro assay. Lethality of TNT in a forest sandy soil was first determined (14-d LC50 = 143 mg/kg). Then TNT at lethal and sublethal concentrations was applied to the same soil and was monitored along with its metabolites in extracts of soil and earthworm tissue for up to 14 d postapplication. High performance liquid chromatography-ultra violet analyses indicated that TNT was transformed in the presence of E. andrei by a reductive pathway to 2-amino-4,6-dinitrotoluene (2-ADNT), 4-amino-2,6-dinitrotoluene (4-ADNT), 2,4-diamino-6-nitrotoluene (2,4-DANT), and traces of 2,6-di-amino-4-nitrotoluene (2,6-DANT) in earthworm tissues. This transformation could be explained by either a metabolic mechanism within the earthworm or by the enhancement of an earthworm-associated microbial activity or both. The TNT concentrations decreased from the spiked soils. However, the monoamino-dinitrotoluene (2-ADNT and 4-ADNT) concentrations increased with exposure duration and were dependent on the initial TNT soil concentrations. This was also observed to a lesser extent in the TNT-spiked soils with no earthworms present. The biotransformation of TNT into 2-ADNT, 4-ADNT, and 2,4-DANT and the presence of these metabolites in E. andrei after dermal contact on TNT-spiked filter paper showed that dermal uptake can be a significant exposure route for TNT. In vitro experiments showed that earthworm homogenate could metabolize TNT and form 2-ADNT and 4-ADNT at room temperature and at 37°C. This effect was inhibited by heat inactivation prior to incubation or by incubation at 4°C, suggesting that the biotransformation of TNT in the presence of E. andrei may be enzymatic in nature.
Influence of bioturbation by the amphipod Corophium volutator on fluoranthene uptake in the marine polychaete Nereis virens
Authors: Ciarelli Silvana , Kater Belinda J , van Straalen Nico M
Published: March 2010

The uptake kinetics of fluoranthene in the polychaete worm Nereis virens were investigated in the presence and in the absence of amphipods to examine the effects of sediment bioturbation by the benthic amphipod Corophium volutator on the uptake in worms. Worms only and worms together with two different densities of amphipods were exposed to fluoranthene-spiked sediment for 12 d. Worms and overlying water samples for fluoranthene analyses were taken and total suspended solids in water column were measured after 1, 2, 5, 8, and 12 d. Results showed that in all treatments fluoranthene was rapidly accumulated by N. virens during the first two days and a steady state was reached within five days of exposure. Biota to sediment accumulation factors normalized to lipid concentration and to sediment organic carbon (BAFloc) of worms exposed with the highest number of amphipods were significantly higher (two to three times) compared to worms exposed with fewer or without amphipods after one and two days of exposure. Bioconcentration factors (BCFs), calculated as the ratio between the uptake (k1) and elimination (k2) rate constants were not significantly different among treatments. When BCFs were calculated on the basis of dissolved fluoranthene concentrations (BCFdiss), values of the treatments where worms were exposed with 100 and 300 amphipods were slightly higher than those calculated on the basis of total (dissolved + particle-bound) aqueous fluoranthene (BCFtot). However, the presence of fluoranthene bound to dissolved organic matter could have accounted for lower than expected BCFdiss values. The results suggest that bioturbation by amphipods affected the concentration of fluoranthene in the worms not by changing the worm to water partitioning (k1/k2) but by changing the worm to sediment partitioning (BAFloc). In the treatments with worms a higher mortality of amphipods was found compared to those without worms. The presence of worms might have contributed to lower BCF values than expected.
No-observed-effect concentrations in batch and continuous algal toxicity tests
Authors: Chao Mu-Rong , Chen Chung-Yuan
Published: March 2010

In this study, we compare the no-observed-effect concentrations (NOECs) based on different response parameters, using batch and continuous algal toxicity tests. For both batch and continuous tests, parameters based on total cell volume (TCV) were found to be less sensitive than those related to cell densities. The above observation mainly occurred because, under the stresses from metal toxicants evaluated in this and a previous study, the mean cell volume (MCV) of algae increased considerably. The increase of MCV compensates for the effects brought about by the reduction in cell density and eventually results in less variation in TCVs. This study shows that parameters based on cell density are quite sensitive and ideal for the estimation of NOECs. In addition, comparison of the NOEC values derived from different culture techniques shows that the continuous method generally yields lower NOEC values than that obtained by the batch tests. The results of this study also indicate that the NOEC provides more protection to the test organism than the effective concentration at 10% growth reduction (EC10). For toxicity test methods that produce small variations among replicates, the NOEC is still a good indicator of low toxic effect. Furthermore, for the continuous algal toxicity test, a relatively simple approach is proposed to determine the NOEC values based on the algal culture's control charts. The proposed method produced identical results as those based on conventional hypothesis-testing methods.
Dietary assimilation of a polychlorinated biphenyl in adult sea urchins (Lytechinus pictus) and maternal transfer to their offspring
Authors: Schweitzer Linda E , Bay Steven M , Suffet I H.(Mel)
Published: March 2010

The dietary assimilation of a polychlorinated biphenyl (PCB) in adult sea urchins and the effects of maternal transfer of the PCB on sea urchin offspring were investigated and compared to an earlier study where this PCB produced toxicity to developing sea urchin embryos exposed directly through the water route. Adult sea urchins were allowed to graze on sediment spiked with radiolabeled PCB, 2,2′,4,4′-tetrachlorobiphenyl, for 35 days. The sea urchin L. pictus was found to have a high pollutant extraction efficiency; approx. 62% of the bulk PCB sediment concentration is removed while passing through the gut. Maternal transfer of PCB 2,2′,4,4′-tetrachlorobiphenyl did not prove to be a more sensitive exposure route to developing embryos than the direct water route. Both adult sea urchins and their offspring were found to be resilient to the effects of this PCB at environmentally relevant sediment concentrations and at levels expected on the basis of the critical body residue theory or the model of narcosis. Low toxicity of PCBs to sea urchins at different life stages allows for significant bioaccumulation in sea urchins.
Effects of water quality on development of Xenopus laevis: A frog embryo teratogenesis assay—Xenopus assessment of surface water associated with malformations in native anurans
Authors: Tietge Joseph E , Ankley Gerald T , DeFoe David L , Holcombe Gary W , Jensen Kathleen M
Published: March 2010

The purpose of this work was to determine if surface water from a site in Minnesota, USA, with malformed anurans was able to elicit adverse developmental effects in the frog embryo teratogenesis assay: Xenopus (FETAX) and to isolate and identify the factors responsible for the effects. In the standard FETAX test, 25 organisms are placed in a 10-ml volume of solution that is renewed daily. The organisms are assessed for abnormal development and the test is terminated at 96 h. Under these conditions, the site water adversely affected craniofacial development, gastrointestinal development, and growth. However, these effects were eliminated by each of several different treatments, including diluting the surface-water sample with the standard testing solution, adding dry salts directly to the surface water, testing the organisms in larger volumes of site water, and evaporating site water to increase the concentration of total dissolved solids. These results are consistent with the hypothesis that the low ion concentrations found in this particular site water were responsible for the developmental effects observed in FETAX. This hypothesis was strengthened further when a reconstituted water, made with deionized water and reagent-grade salts to mimic the content of the site water, affected survival, growth, and development similarly to the surface water. In addition, substantial ammonia accumulation in the FETAX tests was documented. These data suggest that the inherent variability in water quality of field-collected samples is important and could result in artifactual developmental effects when using FETAX. As such, the developmental toxicity observed in these FETAX studies is probably not relevant to malformations observed in native anuran species. To obviate this type of problem, the volumes used in the FETAX protocol should be increased for better organism performance and to reduce the possibility of ammonia toxicity.
Pesticide hydroxyl radical rate constants: Measurements and estimates of their importance in aquatic environments
Authors: Armbrust* Kevin L
Published: March 2010

Pesticide degradation by hydroxyl radicals produced in natural water is often cited as an important dissipation mechanism, yet its significance is rarely assessed with other dissipation processes occurring simultaneously in the aquatic environment. The computer model Exposure Analysis Modeling System (EXAMS) is useful for this purpose because it incorporates other dissipation processes and allows the assessment of their dynamics under different environmental conditions. Rate constants of reaction with photochemically generated hydroxyl radicals were measured for the herbicides sulfometuron, bensulfuron methyl, chlorsulfuron, triclopyr, dicamba, molinate, thiobencarb, 2,4-D, mecoprop, and oxadiazon, for the insecticides chlorpyrifos and imidacloprid, and for the fungicide chlorothalonil by competition kinetic methods and were used as the input value for second-order rate oxidation rate constant (KOX) in EXAMS. Hydroxyl radical degradation was estimated to be most significant in shallow water, where sunlight is less attenuated; however, in relatively clear water, it still could contribute to degradation at greater depths for compounds slowly degraded by other mechanisms. For carbaryl at shallow depths, degradation by hydroxyl radicals was predicted to contribute to less than 1% of the degradation profile at pH 8 to as much as 15% of the profile at pH 6. As unique degradation products may be generated by indirect photolysis mechanisms, it should be possible to use EXAMS to estimate when such products may occur for a particular chemical and environmental situation.
Site-specific marine water-quality criterion for cyanide
Authors: Brix Kevin V , Cardwell Rick D , Henderson Douglas G , Marsden Arnold R
Published: March 2010

A site-specific marine water–quality criterion for cyanide was developed for Puget Sound, Washington, USA. The U.S. Environmental Protection Agency (U.S. EPA) national cyanide water-quality criterion is driven by toxicity data for the eastern rock crab, Cancer irroratus, a species not resident to the U.S. western coast (West Coast). The reported LC50 for C. irroratus is six times lower than any other marine species tested. Cyanide acute toxicity tests were conducted using first stage zoeae of all four species of Cancer spp. resident to Puget Sound to develop a site-specific criterion for this water body. Testing with Puget Sound Cancer spp. reveals sensitivities 24 times less, on average, than C. irroratus. Recalculation of the Puget Sound water-quality criterion for cyanide, by substituting the new Cancer spp. data for the C. irroratus data, results in water-quality criterion protecting marine life against acute and chronic toxicity of 9.4 and 2.9 μg/L cyanide, compared to the U.S. EPA national value of 1.0 μg/L for both acute and chronic toxicity.
Effect of substituent size and dimensionality on potency of phenolic xenoestrogens evaluated with a recombinant yeast assay
Authors: Schultz T Wayne , Sinks Glendon D , Cronin Mark TD
Published: March 2010

Estrogenicity was assessed using the Saccharomyces cerevisiae-based Lac-Z reporter assay and was reported as the logarithm of the inverse of the 50% molar β-galactosidase activity (log[EC50−1]). Previous studies indicated that the position, size, and shape of the nonphenolic moiety of xenoestrogens affects potency. In an effort to quantify the relationship between the size and shape of the nonphenolic moiety and estrogenic potency, a series of primarily hydrocarbon, para-substituted phenols were evaluated. There is a general trend of increase in estrogenicity with increased substituent size. Attempts were made to correlate estrogenic activity with a variety of molecular parameters. These parameters included two-dimensional molecular connectivity and other topological indices, molecular orbital properties and other assorted steric properties, as well as hydrophobicity. Regression analysis revealed that hydrophobicity, because of its colinearity with size, was moderately correlated with estrogenic activity (r2adj = 0.431). Among the parameters describing the bulk and/or shape of the molecule, the second-order path molecular connectivity for the substituent (2χp(sub) was the single best parameter correlated with estrogenicity. It modeled activity by the relationship log(EC50−1) = 0.925(2χp(sub) + 3.47; n = 28, s = 0.37, r2adj = 0.868, f = 179, p > 0.0001. In this model, the active chemical domain is defined by the presence of the para-phenolic ring, while the potency is quantified by the values of the substituent connectivity index. A comparison of 3-, 5-, and 7-d estrogenicity and potency ratio, as compared with 17-β-estradiol, showed some compounds that were not active after the third day but that were active on the fifth and seventh days of exposure. Potency varied with length of exposure, but the potency ratio did not change. These results suggest that activity with this assay should be reported after 5 d of exposure.
An in situ system for exposing aquatic invertebrates to contaminated sediments
Authors: Crane Mark , Higman Mia , Olsen Tony , Simpson Peter , Callaghan Amanda , Fisher Tom , Kheir Rania
Published: March 2010

An in situ system was developed for exposing benthic invertebrates directly to contaminated sediments without exposure to natural overlying waters. This system was used to expose fourth instar Chironomus riparius Meigen larvae for 48 h at 13 uncontaminated river sites across southeast England and at sites along the contaminated River Aire in Yorkshire. Recovery of surviving C. riparius from uncontaminated sites was good (>65%) except when indigenous predatory insect larvae were trapped within test systems. Recovery of survivors from the uncontaminated upstream site in the River Aire was also good (mean survival at Gargrave = 70%), but survival at the two contaminated downstream sites was significantly lower (mean survival of 17.5% at Esholt and 10% at Calverley Bridge). This study has shown that sediments can be isolated from overlying water and effectively bioassayed in situ.
Cadmium accumulation and its effects in growing pheasants Phasianus colchicus (L.)
Authors: Świergosz Renata , Kowalska Anna
Published: March 2010

The aim of the study was to determineCdaccumulationand to assess its effects ontissue s ructure, levels of Fein the tissues, and levels of hematocrit and hemoglobin (Hb) in growing pheasants (Phasianus colchicus). During the three-week experiment, the birds were given food contaminated with 0.05, 40, or 70 μg Cd/g. The birds were weighed and sacrificed at 7-d intervals, and the liver, kidney, testes, muscles, and femur were dissected. Blood samples were taken before sacrifice. Livers were weighed at the seventh and 21st days. The Cd concentrations in all tissues and Fe levels in liver, kidney, muscles, and bone were measured at the seventh, 14th, and 21st days of exposure. Metals were determined by atomic absorption spectrometry. Kidney, liver, and testes were taken for histological analyses under a light microscope. Accumulation of Cd in the tissues was proportional to the dose and duration of exposure. The highest Cd concentration (∼142 μg Cd/g [dry wt]) was found in the kidneys of pheasants fed 70 μg Cd/g. The lowest Cd concentrations were found in muscle (0.03–1.08 μg/g [dry wt]). The mean levels of Cd in the blood of pheasants fed low and high doses of Cd were 0.048 and 0.095 μg/ml, respectively. The Cd accumulation in the tissues caused decreasing Fe and Hb levels in the tissues. The Fe decrease stimulated hematopoiesis in the liver. Despite this, Hb levels were not kept at normal values. Pathological changes from Cd exposure were found in the liver and testes, but the most severe damage was in the kidney. The growth of the pheasants was also slightly retarded. It may be concluded that accumulation of Cd at these levels, which also occurs in the tissues of wild birds from contaminated areas, may cause the same pathological changes and physiological dysfunction.
Use of freshwater rotifer Brachionus calyciflorus in screening assay for potential endocrine disruptors
Authors: Preston Benjamin L , Snell Terry W , Robertson Tish L , Dingmann Brian J
Published: March 2010

eports of the effectsofendocrinedisruptorsonaquatic invertebrates arebecoming increasingly common. However, little is known about the endocrine systems of most aquatic invertebrates, limiting the development of assays based on endocrine mechanisms. As a result, endocrine disruption is often inferred through the effects caused by the chemical of interest, making it difficult to rule out other mechanisms of toxicity. To be a good candidate for an endocrine disruptor, effects should be observed in processes known to be under endocrine control, at life stages where endocrine signals are known to be active, and at concentrations below acute and chronic toxic effects. We developed a 96-h reproductive assay using the freshwater rotifer Brachionus calyciflorus to screen for potential endocrine disruptors and examined cadmium, chlorpyrifos, naphthol, pentachlorophenol, estradiol, methoprene, precocene, nonylphenol, flutamide, and testosterone for effects on asexual and sexual reproduction. Flutamide, testosterone, and nonylphenol inhibited fertilization of sexual females at concentrations of 1, 10, and 50 μg/L, respectively. The fertilization no-observable-effect concentrations (NOECs) for these compounds were 5 to 200 times lower than previously described reproduction NOECs for B. calyciflorus. Sexual reproduction was inhibited with no effects on asexual reproduction, increasing the likelihood that these specific reproductive effects occurred through an endocrine mechanism. Rotifer reproduction assays may be a useful, rapid, and inexpensive method for screening compounds suspected to have endocrine disrupting activity in aquatic invertebrates.
Cellular and molecular basis of cadmium-induced deformities in zebrafish embryos
Authors: Cheng Shuk Han , Wai Albert Wing Kong , So Chun Hung , Wu Rudolf Shiu Sun
Published: March 2010

Cadmium is known to cause developmental defects in a varietyof vertebrate species, but relatively little is known about the underlying molecular mechanisms. In this study, we used zebrafish (Danio rerio) embryos as a model system to investigate cadmium-induced toxicities. Fertilized embryos collected at 5-h after fertilization were incubated for 18 h in culture media containing 1 to 1, 000 μM CdCl2. The median embryolethal concentration (LC50) was 168 μM, whereas the median effect concentration (EC50) for total adverse effect (mortality and developmental defects) was 138 μM. Six major types of deformities were observed: head and eye hypoplasia, hypopigmentation, cardiac edema, yolk sac abnormalities, altered axial curvature, and tail malformations. The frequency of malformations increased with cadmium concentration. Somites of embryos with altered axial curvature were investigated using the antimyosin antibody MF-20. This study demonstrated, to our knowledge for the first time, reduced myotome formation in cadmium-induced spinal deformity. Embryos with head and eye hypoplasia were studied using the anti-neural tissue antibody zns-2, and a poorly developed central nervous system was revealed. Head and eye hypoplasia were associated with lack of expression of the sonic hedgehog gene, which controls the patterning of the neural tube and somites. Genes involved in tail formations, such as evenskipped 1 and no tail, were ectopically expressed in embryos with tail malformations. Our data support the hypothesis that fish embryonic malformations induced by cadmium might be mediated through ectopic expression of developmental regulatory genes.
Toxicity of pesticides to aquatic microorganisms: A review
Authors: DeLorenzo Marie E , Scott Geoffrey I , Ross Philippe E
Published: March 2010

Microorganisms contribute significantly to primary production, nutrient cycling, and decomposition in estuarine ecosystems; therefore, detrimental effects of pesticides on microbial species may have subsequent impacts on higher trophic levels. Pesticides may affect estuarine microorganisms via spills, runoff, and drift. Both the structure and the function of microbial communities may be impaired by pesticide toxicity. Pesticides may also be metabolized or bioaccumulated by microorganisms. Mechanisms of toxicity vary, depending on the type of pesticide and the microbial species exposed. Herbicides are generally most toxic to phototrophic microorganisms, exhibiting toxicity by disrupting photosynthesis. Atrazine is the most widely used and most extensively studied herbicide. Toxic effects of organophosphate and organochlorine insecticides on microbial species have also been demonstrated, although their mechanisms of toxicity in such nontarget species remain unclear. There is a great deal of variability in the toxicity of even a single pesticide among microbial species. When attempting to predict the toxicity of pesticides in estuarine ecosystems, effects of pesticide mixtures and interactions with nutrients should be considered. The toxicity of pesticides to aquatic microorganisms, especially bacteria and protozoa, is an area of research requiring further study.
Response of zooplankton communities to liquid creosote in freshwater microcosms
Authors: Sibley Paul K , Harris Megan L , Bestari Ketut T. (Jim) , Steele Tracey A , Robinson Richard D , Gensemer Robert W , Day Kristen E , Solomon Keith R
Published: March 2010

In this study, the response of zooplankton communities to single applications of liquid creosote in model aquatic ecosystems (microcosms) was evaluated. Liquid creosote was applied to 14 microcosms at concentrations ranging from 0.06 to 109 mg/L. Two microcosms served as controls. Zooplankton samples were collected from each microcosm on days 7 and 1 before treatment and on days 2, 5, 7, 14, 21, 28, 43, 55, and 83 following treatment. Temporal changes (response-recovery) in composition of the zooplankton community were assessed using principal response curves (PRC). Creosote induced a rapid, concentrationdependent reduction in zooplankton abundance and number of taxa, with maximum response (50–100% reduction in population densities) occurring between 5 and 7 d after treatment. Taxa that dominated at the time of treatment experienced the greatest impact, as indicated by large, positive species weight values (>1) from the PRC analysis. Many of these taxa recovered to pretreatment or control levels during the posttreatment period, with the degree and duration of recovery being strongly dependent on concentration. Creosote had little effect on species composition at less than 1.1 mg/L, because changes in the types and relative proportion of species contributed from Cladocera, Rotifera, and Copepoda were comparable to those observed in control microcosms. However, a significant shift in species composition was observed at concentrations greater than 1.1 mg/L; these microcosms were generally dominated by low numbers of rotifers, some of which had not been collected before treatment. Community-level effect concentrations (EC50s) were 44.6 and 46.6 μg/L at 5 and 7 d, respectively, based on nominal creosote. Corresponding no-effect concentrations were 13.9 and 5.6 μg/L. The results of this field study indicate that creosote may pose a significant risk to zooplankton communities at environmental concentrations potentially encountered during spills and/or leaching events.
Effects of nonylphenol ethoxylate exposure on reproductive output and bioindicators of environmental estrogen exposure in fathead minnows, Pimephales promelas
Authors: Nichols Krista M , Snyder Erin M , Snyder Shane A , Pierens Susan L , Miles-Richardson Stephanie R , Giesy John P
Published: March 2010

Nonylphenol ethoxylates (NPEOs) were evaluated in the laboratory for potential effects on the reproductive physiology and fecundity of fathead minnows (Pimephales promelas). Groups of three adult male and three female fathead minnows were exposed in a continuous flow-through system to 0, 0.21, 0.65, 2.1, or 7.9 μg NPEO/L for 42 d. Rabbit anti-goldfish vitellogenin (VTG) antiserum was prepared and a competitive enzyme-linked immunosorbent assay (ELISA) was adapted for measurement of plasma VTG in fish following exposure. Plasma 17β-estradiol (E2) and testosterone (T) were also quantified by ELISA at the end of the exposure. Neither survival nor fecundity of fathead minnows exhibited a concentration-dependent response to NPEOs. No significant differences were observed in plasma VTG concentrations among treatments for males or females. Mean plasma VTG concentrations in females ranged from 291.7 to 895.1 μ VTG/ml among treatments and did not overlap with mean concentrations measured in the plasma of males, which ranged from less than the method detection limit (0.27 μg VTG/ml) to 3.2 μg VTG/ml. Plasma E2 concentrations exhibited a significant difference between males and females within all NPEO treatments, but no differences were observed among treatments. Similarly, plasma T concentrations did not exhibit a concentration-dependent response to NPEOs.
Sublethal effects of silver in zooplankton: Importance of exposure pathways and implications for toxicity testing
Authors: Hook Sharon E , Fisher Nicholas S
Published: March 2010

In aquatic environments, organisms are exposed to contaminants via direct uptake from water and bytrophic transfer. However, most toxicity tests only examine uptake via the dissolved phase. We compared the response of marine and freshwater crustacean zooplankton to silver following dissolved and food exposure. Silver, like other metals, concentrates in aquatic food chains and may exert toxicity. In standard solute exposure toxicity tests, Ag is toxic to zooplankton at concentrations of 400 nM for marine copepods and 100 nM for freshwater cladocerans, concentrations far greater than those in most waters. However, if Ag is accumulated from algal food, reproductive success decreases by >50% when algae are exposed to only 1 nM Ag in copepods and 0.5 nM Ag in cladocerans. These concentrations are within an order of magnitude of those found in contaminated estuaries. Following dietary exposure, decreased egg production and viability occur when tissue Ag concentrations increase three- to fourfold to 0.3 ppm in cladocerans and 0.5 ppm in copepods. Assimilated Ag depresses egg production by reducing yolk protein deposition and ovarian development. Our results indicate that ecologically relevant toxicity tests should consider sublethal effects of contaminants obtained from food since these effects cannot be predicted from exposures to only dissolved contaminants.
Uptake, effects, and metabolism of cyanobacterial toxins in the emergent reed plant Phragmites australis (Cav.) Trin. ex steud
Authors: Pflugmacher Stephan , Wiegand Claudia , Beattie Kenneth A , Krause Eberhard , Steinberg Christian E W , Codd Geoffrey A
Published: March 2010

The commonly occurring cyanobacterial toxin microcystin-LR (MC-LR) was rapidly taken up by the emergent reed plant Phragmites australis with clear distribution in the different cormus parts of the plant. Highest uptake was detected in the stem, followed by the rhizome. Enzyme extracts of the rhizome system, the stem, and the leaf revealed the presence of soluble glutathione S-transferases (sGST) measured with the model substrate 1-chloro-2,4-dinitrobenzene. A significant elevation of sGST activity in the rhizome and stem parts of P. australis was detected after a 24-h exposure to 0.5 μg/L MC-LR. Rhizome, stem, and leaf tissues were also able to conjugate several microcystin toxins. However, no conjugation, either chemical nor enzymatic, was detected using the related cyanobacterial toxin nodularin as substrate. Highest glutathione S-transferase activity for the toxin substrates was detected in the pkat/mg range in the stem of P. australis. For MC-LR, a complete metabolism from the formation of a glutathione conjugate to the degradation of a cysteine conjugate in all cormus parts of the plant is reported. The stepwise degradation of the MC-LR-glutathione conjugate to a γ-glutamylcysteine and a cysteine conjugate was demonstrated by comparison with chemically formed reference compounds and by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This is the first evidence for the uptake and metabolism of cyanobacterial toxins by an emergent aquatic macrophyte.
Negative correlation between plasma thyroid hormone levels and chlorinated hydrocarbon levels accumulated in seals from the coast of Hokkaido, Japan
Authors: Chiba Issei , Sakakibara Akihito , Goto Yoko , Isono Takeomi , Yamamoto Yukie , Iwata Hisato , Tanabe Shinsuke , Shimazaki Kenji , Akahori Fumiaki , Kazusaka Akio , Fujita Shoichi
Published: March 2010

Chlorinated hydrocarbon (CHC) levels in the blubber of larga seals (Phoca largha) and ribbon seals (Phoca fasciata) collected from the coastal waters of Hokkaido, Japan, were determined in order to assess the hormonal effects of CHC exposure in free-ranging pinnipeds. Plasma thyroid hormone levels, including total thyroxine (T4), free thyroxine (free T4), total triiodothyronine (T3), and free triiodothyronine (free T3), were also measured. Higher concentrations of polychlorinated biphenyl congeners (PCBs), dichlorodiphenyltrichloroethane and its metabolites, and chlordane compounds were found in the range of 380 to 2,600 ng/g, 350 to 2,600 ng/g, and 120 to 760 ng/g on a wet-weight basis, respectively. Spearman rank correlation analyses showed that in larga seals, plasma total T3 and free T3 levels negatively correlated with levels of all the CHCs analyzed, although there was no such correlation between total or free T4 levels and CHC concentrations. In ribbon seals, total T3 levels significantly decreased with an increase of di-ortho PCB (PCB170 and 180) residues. These findings indicated that the plasma T3 deficiency could be associated with some CHC exposure in larga and ribbon seals and that the responses of plasma thyroid hormones may be useful biomarkers for CHC exposure in ribbon seals.
Effect of copper on hatching and development of larvae of the estuarine crab Chasmagnathus granulata (Decapoda, Brachyura)
Authors: Zapata Valeria , Greco Laura López , Rodríguez Enrique M
Published: March 2010

Ovigerous females of the estuarine crab Chasmagnathus granulata were exposed to 0.05, 0.1, 0.5, and 3 mg/L of copper during the egg incubation period. Regarding egg loss, a higher effect was observed at higher copper concentrations: 80% of the females lost their eggs at 0.5 mg/L, whereas no hatching was seen in those exposed to 3 mg/L. A significant decrease was found in the number of hatched larvae in females exposed to 0.5 mg/L, as was a significant decrease in the duration of the incubation period. In addition, several morphological abnormalities were seen and observed. Hydropsy and atrophy of the dorsal spine, pleon, and maxillipeds occurred at the higher copper concentrations, as found in previous studies with other pollutants. Hyperpigmentation of the cephalothorax and pleon was the only abnormality observed at every concentration assayed. Hypopigmented eyes were also evident. This pathology showed that among all defects observed at 0.5 mg/L, hypopigmented eyes had the highest incidence and might be a specific response to copper.
Assessment of sediment contamination by spermiotoxicity and embryotoxicity bioassays with sea urchins (Paracentrotus lividus) and oysters (Crassostrea gigas)
Authors: Geffard Olivier , Budzinski Helene , Augagneur Sylvie , Seaman Matthias N L , His Edouard
Published: March 2010

Gametes (sperm) and fertilized eggs (embryos) of the Mediterranean sea urchin, Paracentrotus lividus, and the Japanese oyster, Crassostrea gigas, were used to investigate the toxicity of two marine sediments, one polluted by polycyclic aromatic hydrocarbons (PAH) and the other by heavy metals. The sediment samples were freeze-dried for storage, and three different treatments were used for analysis: whole sediment, unfiltered elutriate, and filtered elutriate. The two sediments were toxic to sea urchin spermatozoa but not to oyster spermatozoa, and embryotoxicity was almost always the more sensitive endpoint for toxicity assessment. As a rule, whole sediment was more toxic than the elutriates by nearly two orders of magnitude. With respect to embryotoxicity, the whole sediments and the elutriates of the PAH-contaminated sediment were more toxic to oyster embryos, whereas the elutriates of the sediment polluted by heavy metals had stronger effects on sea urchin embryos. The results confirm that bioassays with Japanese oyster embryos provide a more sensitive appraisal of toxicity in the marine environment than bioassays with other developmental stages. As a whole, Mediterranean sea urchins and Japanese oysters were similar in overall sensitivity and are therefore both equally suited as bioassay organisms, but tests with oysters are more reproducible because of the better performance of the controls.
Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 5. Probabilistic risk assessment of linear alkylbenzene sulfonates in sludge-amended soils
Authors: Jensen John , Løkke Hans , Holmstrup Martin , Krogh Paul Henning , Elsgaard Lars
Published: March 2010

Linear alkylbenzene sulfonates (LAS) can be found in high concentrations in sewage sludge and, hence, may enter the soil compartment as a result of sludge application. Here, LAS may pose a risk for soil-dwelling organisms. In the present probabilistic risk assessment, statistical extrapolation has been used to assess the risk of LAS to soil ecosystems. By use of a log-normal distribution model, the predicted no-effect concentration (PNEC) was estimated for soil fauna, plants, and a combination of these. Due to the heterogeneous endpoints for microorganisms, including functional as well as structural parameters, the use of sensitivity distributions is not considered to be applicable to this group of organisms, and a direct, expert evaluation of toxicity data was used instead. The soil concentration after sludge application was predicted for a number of scenarios and used as the predicted environmental concentration (PEC) in the risk characterization and calculation of risk quotients (RQ = PEC/PNEC). A LAS concentration of 4.6 mg/kg was used as the current best estimate of PNEC in all RQ calculations. Three levels of LAS contamination (530, 2,600, and 16,100 mg/kg), three half-lives (10, 25, and 40 d), and five different sludge loads (2, 4, 6, 8, and 10 t/ha) were included in the risk scenarios. In Denmark, the initial risk ratio would reach 1.5 in a realistic worst-case consideration. For countries not having similar sludge regulations, the estimated risk ratio may initially be considerably higher. However, even in the most extreme scenarios, the level of LAS is expected to be well beyond the estimated PNEC one year after application. The present risk assessment, therefore, concludes that LAS does not pose a significant risk to fauna, plants, and essential functions of agricultural soils as a result of normal sewage sludge amendment. However, risks have been identified in worst-case scenarios.
Resource allocation-based life histories: A conceptual basis for studies of ecological toxicology
Authors: Congdon Justin D , Dunham Arthur E , Hopkins William A , Rowe Christopher L , Hinton Thomas G
Published: March 2010

Whereas ecological assessments of contaminants are concerned with populations and higher levels of organization, most mechanistic work in toxicology is directed at effects on individuals and their parts. We propose that studies based on individuals can be useful in ecological analysis of polluted systems when based on the concepts of resource allocation-based life history analysis. At the heart of the resource allocation approach is the concept of operative environments of individuals (i.e., environmental factors influencing birth, death, or migration). Contaminants can have strong influences on operative environments, modifying resource allocation strategies that reflect changes in energy assimilation and demands. By examining contaminant-induced responses of individuals from the perspective of changing operative environments, individual-based changes and population dynamics can be addressed in an ecologically rigorous manner.
The use of carbamates, atropine, and 2-pyridine aldoxime methoiodide in the protection of Artemia salina against poisoning by carbophenothion
Authors: Sánchez-Fortún Sebastián , Barahona Victoria
Published: March 2010

The acute toxicity of carbophenothion to three age classes of Artemia salina was evaluated. An increase in toxicity of carbophenothion was found following longer development of A. salina. The effect of pretreatment with the nonselective muscarinic antagonist atropine, the two reversible acetylcholinesterase-inhibitors physostigmine and pyridostigmine, and the cholinesterase-reactivating oxime 2-pyridine aldoxime methochloride (2-PAM) on carbophenothion-induced lethality in 24-h-old A. salina was also investigated. The lethal action of carbophenothion was completely prevented by pretreatment of A. salina with 2-PAM. Atropine and pyridostigmine afforded a maximal protection of approximately 87% and 72%, respectively, compared to control values. In contrast, physostigmine was ineffective. The inhibitory effects of combinations of 10∼5 M atropine with physostigmine, pyridostigmine, or 2-PAM were greater than those elicited by either drug alone, with the maximum protection afforded being 92.58%, 100%, and 100%, respectively. In the presence of 10−7 M atropine, neither pyridostigmine nor 2-PAM provided additional inhibition of the lethality compared to that with either drug alone, whereas the protection afforded by 10∼7 M atropine plus physostigmine increased as the concentration of carbamate increased (up to 10−3 M). Pretreatment with pyridostigmine or physostigmine plus 2-PAM (10−6 M) slightly enhanced the maximal inhibition of carbophenothion lethality compared to that with either drug alone. It is suggested that the most active combined pretreatment studied here was physostigmine plus atropine.
Pollution-induced community tolerance and functional redundancy in a decomposer food web in metal-stressed soil
Authors: Salminen Janne , van Gestel Cornelis A.M. , Oksanen Jari
Published: March 2010

Pollution may lead to the development of pollution-induced community tolerance (PICT) in a stressed community. We studied the presence of PICT in soil food webs using soil microcosms. Soil microcosms containing soil invertebrates and microbes were collected from polluted and unpolluted areas and exposed to a range of soil zinc concentrations. A pine seedling was planted in each microcosm to measure the effects of the origin of the community and Zn pollution on above-ground plant production. The effects of the treatments on nutrient content in the soil were also measured. The diversity of soil microarthropods and the soil's mineral nutrient content were low at the Zn-polluted site. We did not observe an increasing Zn tolerance among the soil organisms in the polluted soil. However, low population growth rates of soil invertebrates from the polluted site may indicate the deleterious effects on fitness of long-lasting pollution. In the soil from the nonpolluted site, Zn additions caused changes in the invertebrate food web structure. These changes were explained by the good physiological condition of the animals and their insensitivity to Zn. The fact that the food web structure in soil from the polluted site did not change can be used as a rough indicator of PICT. Structural stability is presumed by the lack of Zn-sensitive species at this site and the inability of populations to acclimate by altering their growth or reproduction patterns in response to changing soil conditions. Although microbial-based soil decomposer systems may have a high functional redundancy, our results indicate that metal stress at the polluted site exceeds the tolerance limits of the system. As a consequence, ecosystem function at this site is endangered. This study also shows that the evolution of metal tolerance by soil decomposer organisms may not be a common reaction to soil pollution, although changes of population and community structure indicated severe metal stress on organisms.
Life-cycle toxicity of 4-nonylphenol to medaka (Oryzias latipes)
Authors: Yokota Hirofumi , Seki Masanori , Maeda Masanobu , Oshima Yuji , Tadokoro Hiroshi , Honjo Tsuneo , Kobayashi Kunio
Published: March 2010

We studied the chronic effects of 4-nonylphenol (4-NP) on reproductive status of medaka (Oryzias latipes) over two generations of continuous exposure. The exposure study of the parental (F0) medaka was begun on embryos within 24 h postfertilization and continued with monitoring through embryological development, hatching, posthatch survival, growth, sexual differentiation, and reproduction under flow-through exposures to mean measured 4-NP concentrations of 4.2, 8.2, 17.7, 51.5, and 183 μg/L for up to 104 d. Eggs spawned from the F0 fish at 102 and 103 d posthatch were also examined for hatchability, survival after hatching, growth, and sexual differentiation until 60 d posthatch. The 183-μg/L treatment significantly reduced the embryo survival and swim-up success of the F0 fish. The cumulative mortality after swim-up of the F0 fish exposed to 17.7 and 51.5 μg/L were significantly higher than the control mortality. No concentration-related effect of 4-NP was observed on the growth of surviving F0 fish at 60 d posthatch. However, the sex ratio estimated from the appearance of their secondary sex characteristics was skewed toward female in the 51.5μg/L treatment. Additionally, gonadal histology showed that 20% of the fish in the 17.7-μg/L treatment and 40% in the 51.5-μg/L treatment had testis–ova, indicating that 4-NP affects the gonadal development and survival of medaka at similar concentrations in juveniles. The sex ratio of the F0 fish in the 51.5-μg/L treatment was completely skewed toward female; subsequently, the effects on fecundity and fertility in this generation were monitored at mean measured concentrations of 4.2, 8.2, and 17.7 μg/L from 71 to 103 d posthatch. Fecundity was unaffected by any of the treatments examined. The mean fertility in the 17.7-μg/L treatment was reduced to 76% of that in the controls, although no statistically significant differences were determined. Overall, these results indicate that the lowest-observed-effect concentration (LOEC) and no-observed-effect concentration (NOEC) of 4-NP through the life cycle of the F0 medaka were 17.7 and 8.2 μg/L, respectively. In the F1 medaka, no significant effects were observed on hatching success, posthatch mortality, or growth, but sexual differentiation at 60 d posthatch was affected. Induction of testis–ova in the gonads of the F1 fish was observed in both the 8.2- and the 17.7-μg/L concentrations. The results indicate that 4-NP can have significant effects on reproductive potential of medaka at concentrations as low as 17.7 μg/L.