bluuebunny/crossref_metadata_2025 huggingface dataset:
Acute toxicity of heavy metals to acetate-utilizing mixed cultures of sulfate-reducing bacteria: EC100 and EC50
Authors: Utgikar Vivek P , Chen Bor-Yann , Chaudhary Navendu , Tabak Henry H , Haines John R , Govind Rakesh
Published: March 2010

Acid mine drainage from abandoned mines and acid mine pit lakes is an important environmental concern and usually contains appreciable concentrations of heavy metals. Because sulfate-reducing bacteria (SRB) are involved in the treatment of acid mine drainage, knowledge of acute metal toxicity levels for SRB is essential for the proper functioning of the treatment system for acid mine drainage. Quantification of heavy metal toxicity to mixed cultures of SRB is complicated by the confounding effects of metal hydroxide and sulfide precipitation, biosorption, and complexation with the constituents of the reaction matrix. The objective of this paper was to demonstrate that measurements of dissolved metal concentrations could be used to determine the toxicity parameters for mixed cultures of sulfate-reducing bacteria. The effective concentration, 100% (EC100), the lowest initial dissolved metal concentrations at which no sulfate reduction is observed, and the effective concentration, 50% (EC50), the initial dissolved metal concentrations resulting in a 50% decrease in sulfate reduction, for copper and zinc were determined in the present study by means of nondestructive, rapid physical and chemical analytical techniques. The reaction medium used in the experiments was designed specifically (in terms of pH and chemical composition) to provide the nutrients necessary for the sulfidogenic activity of the SRB and to preclude chemical precipitation of the metals under investigation. The toxicity-mitigating effects of biosorption of dissolved metals were also quantified. Anaerobic Hungate tubes were set up (at least in triplicate) and monitored for sulfate-reduction activity. The onset of SRB activity was detected by the blackening of the reaction mixture because of formation of insoluble ferrous sulfide. The EC100 values were found to be 12 mg/L for copper and 20 mg/L for zinc. The dissolved metal concentration measurements were effective as the indicators of the effect of the heavy metals at concentrations below EC100. The 7-d EC50 values obtained from the difference between the dissolved metal concentrations for the control tubes (tubes not containing copper or zinc) and tubes containing metals were found to be 10.5 mg/L for copper and 16.5 mg/L for zinc. Measurements of the turbidity and pH, bacterial population estimations by means of a most-probable number technique, and metal recovery in the sulfide precipitate were found to have only a limited applicability in these determinations.
Effects of bisphenol A and tetrabromobisphenol A on sex organ development in quail and chicken embryos
Authors: Berg Cecilia , Halldin Krister , Brunström Björn
Published: March 2010

The plastic monomere bisphenol A (BPA) and the flame retardant tetrabromobisphenol A (TBBPA) were examined for estrogen-like developmental effects on the reproductive organs in avian embryos. The synthetic estrogen diethylstilbestrol (DES) was used as a positive control. The test compounds were injected into the yolk of quail and chicken eggs early during incubation and the embryos were examined 2 d before anticipated hatching. At 200 μg/g egg, BPA induced Müllerian duct (embryonic oviduct) malformation in female quail embryos and feminization of the left testis (ovotestis) in male chicken embryos. The estrogenic potency of BPA compared with DES was species and endpoint specific. Müllerian duct malformation was the most sensitive endpoint in quail embryos, whereas ovotestis formation was the most sensitive response in chicken embryos. Tetrabromobisphenol A caused high embryo mortality at 45 μg/g egg in both species, but no estrogen-like effects were observed. Bisphenol A caused mortality only in chicken embryos at 67 and 200 μg/g egg. To our knowledge, this is the first report on estrogen-like or embryolethal effects of BPA and TBBPA in birds.
Using a biology-based model (DEBtox) to analyze bioassays in ecotoxicology: Opportunities and recommendations
Authors: Péry Alexandre R. R. , Flammarion Patrick , Vollat Bernard , Bedaux Jacques J. M. , Kooijman Sebastiaan A. L. M. , Garric Jeanne
Published: March 2010

The conventional analysis of bioassays does not account for biological significance. However, mathematical models do exist that are realistic from a biological point of view and describe toxicokinetics and effects on test organisms of chemical compounds. Here we studied a biology-based model (DEBtox) that provides an estimate of a no-effect concentration, and we demonstrated the ability of such a model to adapt to different situations. We showed that the basic model can be extended to deal with problems usually faced during bioassays like time-varying concentrations or unsuitable choices of initial concentrations. To reach this goal, we report experimental data from Daphnia magna exposed to zinc. These data also showed the potential benefit of the model in understanding the influence of food on toxicity. We finally make some recommendations about the choice of initial concentrations, and we propose a test with a depuration period to check the relevance and the predictive capacity of the DEBtox model. In our experiments, the model performed well and proved its usefulness as a tool in risk assessment.
Photodechlorination of 3,3′-dichlorobenzidine in water
Authors: Nyman Marianne C. , Haber Ken S. , Kenttämaa Hilkka I. , Iii Ernest R. Blatchley
Published: March 2010

Laboratory experiments have been conducted to elucidate the photochemical behavior of 3,3′-dichlorobenzidine (DCB) and its congeners in aquatic systems. Photodechlorination of DCB was observed in aqueous samples that were irradiated with monochromatic radiation from a variable-wavelength laser at several wavelengths in the range 300 nm ≤ λ ≤ 360 nm. Analytical measurements performed by high-performance liquid chromatography (HPLC) and Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry revealed that 3-chlorobenzidine (MCB) was produced as a transient intermediate in the photodechlorination process, with subsequent photodechlorination to yield benzidine as a stable photoproduct. Data obtained from these measurements also suggest the existence of other (unidentified) reaction pathways and products. The time-course measurements of chlorobenzidine congener concentrations and irradiance history were combined with a simple reaction model to develop estimates of reaction kinetics. Model predictions were consistent with results obtained for all wavelengths investigated.
Antifungal activity of some trityl-based synthetic dyes
Authors: Oros Gyula , Cserhati Tibor , Forgacs Esther
Published: March 2010

The fungicidal activity of 10 trityl dyes and six reference compounds was determined on 36 fungal strains, and the data matrix was evaluated separately by principal component analysis (PCA) and by spectral mapping technique (SPM). The dimensionality of the maps of the principle component loadings and variables and the selectivity maps were reduced to two by varimax rotation and by nonlinear mapping. Calculations proved that both the strength and selectivity of the fungicidal activity of trityl dyes considerably depended on the chemical structure of the dye and on the type of fungi. Both PCA and SPM were suitable for evaluation of the antifungal activity of dyes; however, the strength and selectivity of the fungicidal effect can be separated only by SPM. Due to its advantageous application parameters, use of SPM in future quantitative structure-activity relationship studies is highly recommended.
Biological properties of arginine-based gemini cationic surfactants
Authors: Pérez Lourdes , Garcia Maria Teresa , Ribosa Isabel , Vinardell Maria Pilar , Manresa Angeles , Infante Maria Rosa
Published: March 2010

Biological properties of novel gemini (double-chain/double-head) cationic surfactants, Nα,Nω-bis(Nα-acylarginine)α,ω-alkylendiamides, so-called bis(Args), are reported. The effect of both the alkyl (10 and 12 carbon atoms) and the spacer chain (from 2–10 methylene groups) of bis(Args) on their antimicrobial activity, acute toxicity on Daphnia magna and Photobacterium phosphoreum, and aerobic biodegradability is studied. These surfactants constitute a novel class of chemicals of low toxicity with excellent surface properties and considerable antimicrobial activity. The aquatic toxicity of these compounds is lower than that of the conventional Monoquats. As regards the biodegradation test, the molecules with a spacer chain ⩽6 methylene groups can be considered as ready biodegradable. The increase of hydrophobicity in the bis(Args) is a negative structural parameter for their environmental behavior.
Reproductive characteristics of male mosquitofish (Gambusia affinis) inhabiting a small southeastern U.S. river receiving treated domestic sewage effluent
Authors: Angus Robert A. , Weaver Season A. , Grizzle John M. , Watson R. Douglas
Published: March 2010

A population of western mosquitofish (Gambusia affinis) living below a wastewater treatment plant in the vicinity of Birmingham (AL, USA) was studied for evidence of exposure to estrogens. Mosquitofish are sexually dimorphic live-bearing fish. Males have an elongated and modified anal fin, called a gonopodium, used in mating. It has been hypothesized that exposure to estrogens and/or anti-androgens in treated wastewater might inhibit the androgen-dependent development of the gonopodium. The population in this study showed no evidence of having been exposed to endocrine-disrupting chemicals. The difference in adjusted (for overall fish size via analysis of covariance) mean gonopodium length between effluent-exposed and control populations was not significant. No detectable levels of vitellogenin were observed in the blood of any of the male mosquitofish, either from the effluent-exposed or the control population. Testes and livers were weighed and examined histologically. The fish exposed to treated wastewater effluent had significantly larger adjusted mean weights for both testis and liver, but no histological changes indicating exposure to estrogens were observed.
Better bootstrap estimation of hazardous concentration thresholds for aquatic assemblages
Authors: Grist Eric P. M. , Leung Kenneth M. Y. , Wheeler James R. , Crane Mark
Published: March 2010

The introduction of species sensitivity distribution (SSD) approaches to ecological risk assessment offers the potential for a more transparent scientific basis for the derivation of predicted no-effect concentrations. However, conventional SSD methodologies have relied on standard distributions (e.g., log logistic, log normal) that are not necessarily based on sound ecological or statistical grounds. More recently, bootstrap resampling techniques that do not rely on distributional assumptions have been applied to the problem. Here we describe how a more advanced bootstrap methodology may be applied to derive better point estimates and confidence intervals for SSD estimates of safe environmental concentrations. Motivated by the fact that the true SSD may not fit any standard model category, we go on to consider a hybrid bootstrap regression approach. This can yield a substantially different estimate for the SSD when compared with both the basic bootstrap and the more frequently used parametric curve approaches. With increasing use of SSDs in ecological risk assessment, it is now imperative that the scientific community develops agreement over appropriate methods for their derivation.
Loss of capacity to elevate plasma cortisol in rainbow trout (Oncorhynchus mykiss) treated with a single injection of o,p′-dichlorodiphenyldichloroethane
Authors: Benguira Sandrine , Leblond Vincent S. , Weber Jean-Philippe , Hontela Alice
Published: March 2010

The organochlorine o,p′- dichlorodiphenyldichloroethane (o,p′-DDD) is a metabolite of dichlorodiphenyltrichloroethane (DDT), known for its adrenolytic actions in birds and mammals. The effects of o,p′-DDD on the cortisol stress response were investigated in rainbow trout, Oncorhynchus mykiss, in a dose-response study in vivo. A dose-dependent decrease in plasma cortisol levels was observed on days 7 and 14 after a single i.p. injection of o,p′-DDD. Treatment with o,p′-DDD had no effect on weight gain, hematocrit, and gonado- or hepatosomatic index but decreased liver glycogen reserves. The results indicate that o,p′-DDD is an adrenotoxic compound in rainbow trout and that its effects can be detected even 14 d postinjection.
Sponge halogenated natural products found at parts-per-million levels in marine mammals
Authors: Vetter Walter , Stoll Elke , Garson Mary J. , Fahey Shireen J. , Gaus Caroline , Müller Jochen F.
Published: March 2010

Several unknown, abundant brominated compounds (BCs) were recently detected in the blubber of dolphins and other marine mammals from Queensland (northeast Australia). The BCs were interpreted as potential natural products due to the lack of anthropogenic sources for these compounds. This study investigated whether some of the BCs accumulated by diverse marine mammal species are identical with natural BCs previously isolated from sponges (Dysidea sp.) living in the same habitat. Isolates from sponges and mollusks (Asteronotus cespitosus) were compared with the signals detected in the mammals' tissue. Mass spectra and gas chromatography retention times on four different capillary columns of the isolates from sponges and mammals were identical in all respects. This proves that the chemical name of the compound previously labeled BC-2 is 4,6-dibromo-2-(2′,4′-dibromo)phenoxyanisole and that the chemical name of BC-11 is 3,5-dibromo-2-(3′,5′-dibromo,2′-methoxy)phenoxyanisole. Using a quantitative reference solution of BC-2, we established that the concentrations of the brominated metabolites found in the marine mammals are frequently >1 mg/kg. The highest concentration (3.8 mg/kg), found in a sample of pygmy sperm whale (Kogia breviceps), indicates that BC-2 is a bioaccumulative, natural organohalogen compound. This is supported by the concentrations of the BCs in our samples being equal to the highest concentrations of anthropogenic BCs in any environmental sample. The quantitative determination of BC-2 in blubber of marine mammals from Africa and the Antarctic suggests that BC-2 is widespread. These results are direct proof that marine biota can produce persistent organic chemicals that accumulate to substantial concentrations in higher trophic organisms.
Level and extent of mercury contamination in Oregon, USA, lotic fish
Authors: Peterson Spencer A. , Herlihy Alan T. , Hughes Robert M. , Motter Kathryn L. , Robbins James M.
Published: March 2010

We conducted a probability survey of 154 Oregon, USA, stream and river sites to assess the spatial extent of mercury (Hg) contamination in fish tissue. Samples consisted of whole-fish analyses of both small (<120 mm) and large (>120 mm) fish at each site, when both were present. Overall, Hg levels (μg/g in small fish (X = 0.031; standard deviation [SD] = 0.029), large piscivores (X = 0.284; SD = 0.175), and large invertivores (X = 0.055; SD = 0.047) were found within fairly narrow ranges; always above detection (0.0025 μg/g) and almost always below 0.4 μg/g. Given the great ecoregion diversity across Oregon, the narrow range in fish tissue Hg levels suggests that atmospheric transport is an important vehicle for Hg distribution. In small fish, Hg levels were almost always low and showed little meaningful difference among fish taxa. In large fish, Hg levels were significantly related to fish length. Piscivores (pikeminnow and bass) had significantly higher Hg levels, and the slope of their Hg level/length relationship was much steeper than for invertivores. Salmonids, the most commonly occurring fish taxon in Oregon, exceeded 0.1 μg Hg/g (deemed protective for fish-eating mammals) in an inferred 15% of stream lengths where they occurred. Pikeminnows and bass were found at fewer sites, but they exceeded 0.1 μg Hg/g in an inferred 96 and 70%, respectively, of stream lengths where they occurred.
Dichlorodiphenyltrichloroethane in the aquatic ecosystem of the Okavango Delta, Botswana, South Africa
Authors: Mbongwe Bontle , Legrand Melissa , Blais Jules M. , Kimpe Lynda E. , Ridal J. Jeffrey , Lean David R. S.
Published: March 2010

Concentrations of DDT and its metabolites were measured in water, plants, invertebrates, and fish from lagoons in the Okavango Delta, Botswana (Africa), where DDT has been used for approximately 50 years. The sampling area was sectioned to distinguish spraying for malaria and for African sleeping sickness. Average concentrations of total DDT (sum of DDT and its metabolites) in the Okavango ranged from 0.009 ng/L in water to 18.76 ng/g wet weight in fish. These levels are approximately 1% of those found in piscivorous fish from temperate North America. The dichlorodiphenyl ethylene (DDE) metabolite was the most abundant fraction of total DDT. Although total DDT concentrations were higher in areas treated for malaria than areas treated for sleeping sickness, these concentrations were likely driven by factors other than the historic application of the pesticide. Equilibration with air concentrations is the most likely explanation for these levels. Since the mean annual temperature exceeds the temperature of vaporization of DDT, this research points to the need for reliable transport models. Our results showed that total DDT concentration in fish was best explained by lipid content of the fish and trophic position inferred by δ15N, regardless of DDT application history in those areas. The reservoir above Gaborone Dam, an area downstream of the Okavango but where DDT had not been used, was sampled to compare total DDT levels to the treated areas. The two species (a herbivorous threespot talapia and the omnivorous sharptooth catfish) from Gaborone had levels higher than those found in the Okavango Delta, but these differences can again be explained using trophic position inferred by δ15N rather than by fish size or location.
Selected resin acids in effluent and receiving waters derived from a bleached and unbleached kraft pulp and paper mill
Authors: Quinn Brian P. , Booth Matthew M. , Delfino Joseph J. , Holm Stewart E. , Gross Timothy S.
Published: March 2010

Water samples were collected on three dates at 24 sites influenced by effluent from Georgia-Pacific's Palatka Pulp and Paper Mill Operation, a bleached and unbleached kraft mill near Palatka, Florida, USA. The sampling sites were located within the mill retention ponds, Rice Creek, and the St. John's River. Samples were analyzed by gas chromatography-mass spectrometry for abietic, dehydroabietic, and isopimaric acids, all of which are potentially toxic by-products of pulp production. Isopimaric acid concentrations greater than 12 mg/L were measured at the mill's effluent outfall but were less than 20 μg/L at the end of Rice Creek. This result indicates that the waters of Rice Creek provide dilution or conditions conducive for degradation or sorption of these compounds. Large differences in resin acid concentrations were observed between sampling events. In two sampling events, the maximum observed concentrations were less than 2 mg/L for each analyte. In a third sampling event, all of the compounds were detected at concentrations greater than 10 mg/L. Data from the three sample dates showed that resin acid concentrations were below 20 μg/L before the confluence of Rice Creek and the St. John's River in all cases.
Response of larval Xenopus laevis to atrazine: Assessment of growth, metamorphosis, and gonadal and laryngeal morphology
Authors: Carr James A. , Gentles Angie , Smith Ernest E. , Goleman Wanda L. , Urquidi Lina J. , Thuett Kerry , Kendall Ronald J. , Giesy John P. , Gross Tim S. , Solomon Keith R. , Van Der Kraak Glen
Published: March 2010

Larval Xenopus laevis were exposed to one of four concentrations of atrazine (0, 1, 10, or 25 μg/L, 11 replicate tanks per treatment, 60–65 larvae per replicate) dissolved in an artificial pond water (frog embryo teratogenesis assay-Xenopus [FETAX]) medium beginning 48 h after hatching until the completion of metamorphosis. Separate groups of larvae (six replicate tanks per treatment, 60–65 larvae per replicate) were exposed to estradiol (100 μg/L), dihydrotestosterone (100 μg/L), or ethanol vehicle control dissolved in FETAX medium. None of the treatments affected posthatch mortality, larval growth, or metamorphosis. There were no treatment effects on sex ratios except for estradiol, which produced a greater percentage of female offspring. Exposure to either estradiol or 25 μg atrazine/L increased the incidence of intersex animals based on assessment of gonadal morphology. Atrazine did not reduce the size of the laryngeal dilator muscle, a sexually dimorphic muscle in this species. We conclude that environmentally relevant concentrations of atrazine do not influence metamorphosis or sex ratios and do not inhibit sexually dimorphic larynx growth in X. laevis. The incidence of atrazine-induced intersex animals was small (<5%) and occurred only at the greatest concentration of atrazine tested, a concentration that is rarely observed in surface waters in the United States.
Occurrence of several arsenic compounds in the liver of birds, cetaceans, pinnipeds, and sea turtles
Authors: Kubota Reiji , Kunito Takashi , Tanabe Shinsuke
Published: March 2010

Concentrations of total arsenic and individual arsenic compounds were determined in livers of birds, cetaceans, pinnipeds, and sea turtles by using hydride generation-atomic absorption spectrometry and high-performance liquid chromatography/inductively coupled plasma-mass spectrometry. Hepatic arsenic concentrations in loggerhead turtles (11.2 ± 3.0 μg/g dry wt) and black-footed albatrosses (12.2 ± 10.8 μg/g dry wt) were extremely high among the species examined, and the values were comparable with those of lower trophic marine animals such as fishes, cephalopods, crustaceans, and shellfishes. In all the species, arsenobetaine was the predominant arsenic compound in the livers. Especially, for black-footed albatrosses and black-tailed gull, the mean percentage of arsenobetaine was as high as 97.1 and 87.5, respectively, of extractable arsenic. The present study is among the first on arsenic speciation in avian species. Total arsenic concentration was strongly correlated with the concentration of arsenobetaine, while no significant relationship was observed between total arsenic concentration and other arsenic compounds in these animals. Because arsenobetaine is known to be rapidly excreted into the urine in humans and experimental animals, the observed results suggest that higher trophic marine animals might have a unique metabolism of arsenobetaine and that arsenobetaine plays an important role in the accumulation of arsenic in these animals.
Testosterone metabolism in the estuarine mysid Neomysis integer (Crustacea; Mysidacea) following tributyltin exposure
Authors: Verslycke Tim , Poelmans Sofie , De Wasch Katia , Vercauteren Jordy , Devos Christophe , Moens Luc , Sandra Patrick , De Brabander Hubert F. , Janssen Colin R.
Published: March 2010

Current evidence suggests that the biocide tributyltin (TBT) causes the development of imposex, a state of pseudoher-maphrodism in which females exhibit functional secondary male characteristics, by altering the biotransformation or elimination of testosterone. Imposex in gastropods following TBT exposure is the most complete example of the effects of an endocrine disrupter on marine invertebrates. Previous studies have demonstrated that the estuarine mysid Neomysis integer converts testosterone into multiple polar and nonpolar metabolites resulting from both phase I and phase II biotransformations. In this study, the effects of TBT chloride (TBTCl) on the phase I and II testosterone metabolism of N. integer were evaluated. The TBTCl was highly toxic to N. integer (96-h median lethal concentration [LC50] of 164 ng/L). To assess the effects on testosterone metabolism, mysids were exposed for 96 h to different concentrations of TBTCl (control, 10, 100, and 1,000 ng/L), and testosterone elimination as polar hydroxylated, nonpolar oxido-reduced, and glucose- and sulfate-conjugated metabolites was examined. The TBTCl differentially affected testosterone metabolism. The effect of TBTCl on phase I metabolism was unclear and has been shown to vary among species, likely depending on the inducibility or presence of certain P450 isozyme families. Reductase activity and metabolic androgenization were induced in the 10-ng/L treatment, whereas higher concentrations resulted in a reduction of sulfate conjugation. The exact mechanisms underlying TBT-induced imposex and alterations in the steroid metabolism need to be further elucidated.
Differential effects of copper and cadmium exposure on toxicity endpoints and gene expression in Chlamydomonas reinhardtii
Authors: Stoiber Tasha L. , Shafer Martin M. , Armstrong David E.
Published: March 2010

The toxicity of cadmium to aquatic organisms is well known, but the mechanisms of toxicity are not as clearly understood. In the present study, Cd bioassay experiments incorporating both traditional endpoints and novel thiol-based endpoints were conducted with Chlamydomonas reinhardtii. The results were compared with results from previous bioassay experiments to probe the apparent contrasting biochemical mechanisms of toxicity of copper and cadmium as expressed in cellular glutathione and the glutathione cycle. Total glutathione and reduced to oxidized glutathione ratio (GSH/GSSG) measurements were remarkably different in Cd- compared with Cu-exposed cells. Whereas total glutathione in cells decreased with increasing Cu concentration, Cd caused dramatic increases. Total glutathione increased by 4.5-fold with 80 nM Cd treatment over concentrations in Cd-free controls. Glutathione reductase (GR) enzyme activity was positively correlated (r2Cu = 0.96, r2Cd = 0.85) with glutathione concentrations for both metals. Measurements of mRNA for GR were increased 2-fold in response to Cd exposure (80 nM) and correlated well with GR enzyme activity. Glutathione concentrations and GR enzyme activity are useful endpoints for both Cu and Cd toxicity in algae, even though the metals elicit opposing responses. We conclude that Cu decreases glutathione concentrations by inhibiting GR enzyme activity. In contrast, Cd stimulates GR enzyme activity and increases glutathione concentrations as cells respond to Cd-induced stress by producing increased antioxidant capacity. The present study demonstrates that determining the glutathione response in cells is important for understanding the metal-specific mechanisms of toxicity and that these associated novel endpoints may be useful metrics for accurately predicting toxicity. Environ. Toxicol. Chem. 2010;29:191–200. © 2009 SETAC
Selenium distribution in a lake system receiving effluent from a metal mining and milling operation in Northern Saskatchewan, Canada
Authors: Wiramanaden Cheryl I. E. , Forster Erin K. , Liber Karsten
Published: March 2010

The release of selenium (Se) at relatively low concentrations into aquatic ecosystems over time can result in the accumulation and, if thresholds are exceeded, subsequent adverse effects in sensitive species, including higher trophic levels (such as fish). A milling operation in Northern Saskatchewan, Canada, releases treated effluent into a small stream system, and Se has accumulated in sediments and aquatic biota over time. The present study evaluated four small lakes downstream of the effluent discharge point, and one lake upstream, in order to describe and understand the distribution of Se in abiotic environmental compartments and the transfer of Se into benthic macroinvertebrates. The concentrations of Se in sampled sediments were highly variable but exceeded proposed thresholds for the protection of fish and aquatic birds in all study lakes downstream of the effluent discharge point. Selenium concentrations in surface water, whole-sediment, and sediment pore water revealed that whole-body Se concentrations in benthic invertebrates (chironomids) are best correlated with Se in pore water. It is proposed that Se accumulates in sediments through an association with the total organic carbon content of sediment and that Se is fixed from the surface water by micro-organisms and primary producers. The relationship between Se in pore water and Se in whole sediments appears to be influenced by the organic carbon content of each medium, and Se bioavailability in sediment and transfer to higher trophic levels via benthic macroinvertebrates is likely speciation dependent. Environ. Toxicol. Chem. 2010;29:606–616. © 2009 SETAC
Enhanced reproduction in mallards fed a low level of methylmercury: An apparent case of hormesis
Authors: Heinz Gary H. , Hoffman David J. , Klimstra Jon D. , Stebbins Katherine R.
Published: March 2010

Breeding pairs of mallards (Anas platyrhynchos) were fed a control diet or a diet containing 0.5 µg/g mercury (Hg) in the form of methylmercury chloride. There were no effects of Hg on adult weights and no overt signs of Hg poisoning in adults. The Hg-containing diet had no effect on fertility of eggs, but hatching success of eggs was significantly higher for females fed 0.5 µg/g Hg (71.8%) than for controls (57.5%). Survival of ducklings through 6 d of age was the same (97.8%) for controls and mallards fed 0.5 µg/g mercury. However, the mean number of ducklings produced per female was significantly higher for the pairs fed 0.5 µg/g Hg (21.4) than for controls (16.8). Although mercury in the parents' diet had no effect on mean duckling weights at hatching, ducklings from parents fed 0.5 µg/g Hg weighed significantly more (mean = 87.2 g) at 6 d of age than did control ducklings (81.0 g). The mean concentration of Hg in eggs laid by parents fed 0.5 µg/g mercury was 0.81 µg/g on a wet-weight basis. At this time, one cannot rule out the possibility that low concentrations of Hg in eggs may be beneficial, and this possibility should be considered when setting regulatory thresholds for methylmercury. Environ. Toxicol. Chem. 2010;29:650–653. © 2009 SETAC
Triclocarban, triclosan, polybrominated diphenyl ethers, and 4-nonylphenol in biosolids and in soil receiving 33-year biosolids application
Authors: Xia Kang , Hundal Lakhwinder S. , Kumar Kuldip , Armbrust Kevin , Cox Albert E. , Granato Thomas C.
Published: March 2010

Land application of biosolids is a common practice throughout the world. However, concerns continue to be raised about the safety of this practice, because biosolids may contain trace levels of organic contaminants. The present study evaluated the levels of triclocarban (TCC), triclosan (TCS), 4-nonylphenol (4-NP), and polybrominated diphenyl ethers (PBDEs) in biosolids from 16 wastewater treatment plants and in soils from field plots receiving annual applications of biosolids for 33 years. All of the four contaminants evaluated were detected in most of the biosolids at concentrations ranging from hundreds of µg/kg to over 1,000 mg/kg (dry wt basis). They were detected at µg/kg levels in the biosolids-amended soil, but their concentrations decreased sharply with increasing soil depth for 4-NP, PBDEs, and TCC, indicating limited soil leaching of those compounds. However, potential leaching of TCS in the biosolids-amended soils was observed. The levels of all four compounds in the surface soil increased with increasing biosolids application rate. Compared with the estimated 33-year cumulative input to the soil during the 33-year consecutive biosolids application, most of the PBDEs and a small percentage of 4-NP, TCC, and TCS remained in the top 120-cm soil layer. These observations suggest slow degradation of PBDEs but rapid transformation of 4-NP, TCC, and TCS in the biosolids-amended soils. Environ. Toxicol. Chem. 2010;29:597–605. © 2009 SETAC
Physiological and potential genetic toxicity of chlortetracycline as an emerging pollutant in wheat (Triticum aestivum L.)
Authors: Xie Xiujie , Zhou Qixing , He Zhangchun , Bao Yanyu
Published: March 2010

Increasing attention is now being paid to antibiotic contamination as a serious environmental issue. Chlortetracycline has been widely used for decades as a human and veterinary medicine, which has resulted in environmental residues and damage to living organisms. In the present study, the physiological and potential genetic toxicity of chlortetracycline was investigated using a wheat (Triticum aestivum L.) bioassay at a concentration range of 0.0625 to 300 mg/L and an exposure time of 24, 48, and 72 h. The results indicated that chlortetracycline at the lower concentrations stimulated germination and cell mitotic division and growth, whereas higher concentrations significantly inhibited processes such as bud length (50–300 mg/L), percentage germination (25–300 mg/L), root length (25–300 mg/L), and mitotic index (MI) (25–300 mg/L). The lowest concentration of chlortetracycline slightly augmented the frequency of micronucleus (MN), chomosomal aberration (CA), and sister chomatid exchange (SCE) in the root tips; however, significant (p < 0.05 and 0.01) levels of augmentation were observed at higher concentrations in a concentration-dependent manner, including the frequencies of MN (25–200 mg/L), CA (10–200 mg/L), and SCE (5–200 mg/L), respectively. The inducement of MN, CA, and SCE decreased at 250 and 300 mg/L as a result of acute cell toxicity. In addition, all endpoints showed a time-dependent increase at 0.0625 to 200 mg/L. These results imply that chlortetracycline (≥5 mg/L) may be genotoxic to plant cells, and exposure to chlortetracycline may pose a potential genotoxic risk to living organisms. Comparatively, SCE was the most sensitive, followed by CA, and MN was the least sensitive to chlortetracycline genotoxicity in wheat. The results also suggest that the wheat bioassay is efficient, simple, and reproducible for monitoring the genotoxicity of chlortetracycline in the environment. Environ. Toxicol. Chem. 2010;29:922–928. © 2009 SETAC
Kinetic bacterial bioluminescence assay for contact sediment toxicity testing: Relationships with the matrix composition and contamination
Authors: Bláha Ludek , Hilscherová Klara , Čáp Tomáš , Klánová Jana , Machát Jiří , Zeman Josef , Holoubek Ivan
Published: March 2010

The present study represents the first broader evaluation of the rapid 30-s kinetic bioluminescence assay with Vibrio fisheri (microplate format modification) for contact toxicity testing of whole sediments. The present study focused on river sediments from the Morava River basin, Czech Republic, repeatedly sampled during 2005 to 2006 and analyzed for geological and geochemical parameters, content of toxic metals, major organic pollutants, and toxicity. High natural variation in toxicity (50% inhibitory concentration [IC50] values ranging from 0.8 to >80 mg sediment dry wt/ml) was found (among different sampling periods and years, among sites), and this could be related to the sediment dynamics affected by spring high flows and summer droughts. From the 46 sediment descriptors, exchangeable protons (H+) was the only parameter that consistently correlated with toxicity. Three other descriptors (i.e., content of organic carbon plus two parameters from the detailed silicate analysis of sediments: percentage of SO3 representing total sulfur content, structural water H2O+) also significantly correlated with toxicity. There were only minor and variable correlations with contamination. We propose sediment safety guideline categories for the V. fisheri kinetic test with severe toxicity threshold of IC50 < 1 mg dry wt/ml. Although sediments are considered a rather stable matrix in comparison with river water, we confirmed high variability and dynamics that should be reflected in monitoring plans and field studies. Environ. Toxicol. Chem. 2010;29:507–514. © 2009 SETAC
Seasonally and regionally determined indication potential of bioassays in contaminated river sediments
Authors: Hilscherová Klára , Dušek Ladislav , Šídlová Tereza , Jálová Veronika , Čupr Pavel , Giesy John P. , Nehyba Slavomír , Jarkovský Jiří , Klánová Jana , Holoubek Ivan
Published: March 2010

River sediments are a dynamic system, especially in areas where floods occur frequently. In the present study, an integrative approach is used to investigate the seasonal and spatial dynamics of contamination of sediments from a regularly flooded industrial area in the Czech Republic, which presents a suitable model ecosystem for pollutant distribution research at a regional level. Surface sediments were sampled repeatedly to represent two different hydrological situations: spring (after the peak of high flow) and autumn (after longer period of low flow). Samples were characterized for abiotic parameters and concentrations of priority organic pollutants. Toxicity was assessed by Microtox test; genotoxicity by SOS-chromotest and green fluorescent protein (GFP)-yeast test; and the presence of compounds with specific mode of action by in vitro bioassays for dioxin-like activity, anti-/androgenicity, and anti-/estrogenicity. Distribution of organic contaminants varied among regions and seasonally. Although the results of Microtox and genotoxicity tests were relatively inconclusive, all other specific bioassays led to statistically significant regional and seasonal differences in profiles and allowed clear separation of upstream and downstream regions. The outcomes of these bioassays indicated an association with concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) as master variables. There were significant interrelations among dioxin-like activity, antiandrogenicity and content of organic carbon, clay, and concentration of PAHs and PCBs, which documents the significance of abiotic factors in accumulation of pollutants. The study demonstrates the strength of the specific bioassays in indicating the changes in contamination and emphasizes the crucial role of a well-designed sampling plan, in which both spatial and temporal dynamics should be taken into account, for the correct interpretations of information in risk assessments. Environ. Toxicol. Chem. 2010;29:522–534. © 2009 SETAC
Assessment of contamination of the Svitava and Svratka rivers in the Czech Republic using selected biochemical markers
Authors: Blahová Jana , Havelková Marcela , Kružíková Kamila , Hilscherová Klára , Halouzka Roman , Modrá Helena , Grabic Roman , Halířová Jarmila , Jurčíková Jana , Ocelka Tomáš , Haruštiaková Danka , Svobodová Zdeňka
Published: March 2010

The aim of the present study is to assess aquatic ecosystem contamination using selected biochemical markers: cytochrome P450, ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), tripeptide glutathione, vitellogenin, and 11-ketotestosterone in chub (Leuciscus cephalus L.). Seven locations on the Svitava and Svratka rivers (in the Brno conurbation, Czech Republic) were assessed. The results were compared with the levels of the most important inductors of these biomarkers: organic pollutants hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), DDT and its metabolites, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons in bottom sediment, fish muscle, and semipermeable membrane devices (SPMDs) and metals in sediment. The highest levels of pollutants were observed at sites situated downstream from Brno, especially at Modřice and Rajhradice. Significant positive correlations (p < 0.05) were found between EROD activity and HCH concentration in SPMDs, and also between GST and EROD activity with HCB concentration in muscle, after adjusting for age. Environ. Toxicol. Chem. 2010;29:541–549. © 2009 SETAC
Enhanced migration of polychlorodibenzo-p-dioxins and furans in the presence of pentachlorophenol-treated oil in soil around utility poles: Screening model validation
Authors: Bulle Cécile , Samson Réjean , Deschênes Louise
Published: March 2010

Field samples were collected around six pentachlorophenol (PCP)-treated wooden poles (in clay, organic soil, and sand) to evaluate the vertical migration of polychlorodibenzo-p-dioxins and furans (PCDD/Fs). Soils were characterized, PCDD/Fs, C10-C50, and PCP were analyzed for seven composite samples located at a depth from 0 to 100 cm and at a distance from 0 to 50 cm from each pole. Concentrations of PCDD/Fs measured in organic soils were the highest (maximum 1.2E + 05 pg toxic equivalent TEQ/g soil), followed by clay (maximum 3.8E + 04 pg TEQ/g soil) and sand (maximum 1.8E + 04 pg TEQ/g soil). Model predictions, including the influence of wood treatment oil, were validated using measured concentration values in soils around poles. The model predicts a migration of PCDD/Fs due to the migration of oil, which differs depending on the type of soil: in clay, 90% of PCDD/Fs are predicted to remain in the first 29 cm, whereas in sand, 80 to 90% of the emitted PCDD/Fs are predicted to migrate deeper than 185 cm. For the organic soil, the predicted migration depth varies from 90 to 155 cm. This screening model allows evaluating the danger of microcontaminated sites around PCP-treated wooden poles: from a risk assessment perspective, in the case of organic soil and clay, no PCDD/F contamination is to be expected below the pole, but high levels of PCDD/Fs can be found in the first 2 m below the surface. For sand, however, significantly lower levels of PCDD/Fs were predicted in the surface soil, while the migration depth remains elevated, posing an inherent danger of aquifer contamination under the pole. Environ. Toxicol. Chem. 2010;29:582–590. © 2009 SETAC
Thermal tolerance of juvenile freshwater mussels (Unionidae) under the added stress of copper
Authors: Pandolfo Tamara J. , Cope W. Gregory , Arellano Consuelo
Published: March 2010

Freshwater mussels fulfill an essential role in aquatic communities, but are also one of the most sensitive and rapidly declining faunal groups in North America. Rising water temperatures, caused by global climate change or industrial discharges, can further challenge impaired unionid communities, but thermal stress is almost certainly not the only stressor affecting freshwater mussels. Metals, such as copper (Cu), are a common source of toxicant exposure in aquatic environments. The toxic effects of Cu on the early life stages of freshwater mussels have been well studied, and freshwater mussels are more sensitive to Cu than most aquatic organisms. The purpose of the present study was to determine the effect of a sublethal copper concentration on the upper thermal tolerance of three species, Lampsilis siliquoidea, Potamilus alatus, and Ligumia recta, of juvenile freshwater mussels in 48- and 96-h tests. Thermal tolerance was determined over a range of experimental temperatures (20–42°C) at three acclimation temperatures (17, 22, and 27°C). Median lethal temperatures (LT50s) were calculated in the absence and presence of Cu, and at 48 h ranged from 34.6 to 44.4°C (mean 37.7°C) without Cu, and from 33.8 to 38.9°C (mean 35.8°C) with Cu. The LT50s at 96 h ranged from 32.5 to 35.6°C (mean 34.5°C) without Cu and from 33.0 to 35.4°C (mean 34.2°C) with Cu. Potamilus alatus had a significantly lower 48 h LT50 with Cu than without Cu at the 22°C acclimation temperature; there were no other significant differences in LT50s attributed to Cu. Survival trends showed limited evidence of interactive effects between copper and temperature for all three species, suggesting the combined stress of elevated temperatures and copper exposure to freshwater mussels should be further explored. Environ. Toxicol. Chem. 2010;29:691–699. © 2009 SETAC
Genetic costs of tolerance to metals in Daphnia longispina populations historically exposed to a copper mine drainage
Authors: Agra Ana Raquel , Guilhermino Lúcia , Soares Amadeu M.V.M. , Barata Carlos
Published: March 2010

The present study was conducted to assess three microevolutionary aspects of adaptation to pollution in Daphnia longispina populations historically exposed to an acid mine drainage from an abandoned pyrite mine: pollution mediated effects in acute tolerance to copper (Cu) and zinc (Zn); pollution-mediated effects on genetic variability of tolerant and physiological traits related to fitness (feeding rates); and fitness costs of tolerance measured as genetic trade-offs between tolerance and feeding rates under none and low levels of contamination. These objectives were addressed by comparing broad sense heritabilities and genetic correlations using up to 20 distinct clonal lineages randomly obtained from two populations: one located in a water reservoir contaminated by the acid mine drainage, and the other located in a nearby clean water reservoir. Results showed that only sensitive and resistant lineages to Cu were present in the reference and contaminated site, respectively. For Zn, however, both populations had a similar distribution pattern of sensitivities. Heritability values for tolerant and feeding traits across metal exposure levels was similar in both populations being in most cases greater than 50%. Fitness costs of tolerance were illustrated by lower feeding rates of the tolerant population compared to the reference one and negative genetic correlations between mean clonal feeding rates and median clonal survival time in control conditions (no added Cu or Zn). The results obtained thus support the view that tolerance to pollution is ecologically costly. Environ. Toxicol. Chem. 2010;29:939–946. © 2009 SETAC
Effects of pesticides and antibiotics on penaeid shrimp with special emphases on behavioral and biomarker responses
Authors: Tu Huynh Thi , Silvestre Frederic , Phuong Nguyen Thanh , Kestemont Patrick
Published: March 2010

The purpose of the present study is to provide information on the current state of knowledge regarding the effects of pesticides and antibiotics used in aquaculture on penaeid shrimp, one of the most common aquatic products for human consumption, with a special emphasis on the use of behavioral, physiological, and biochemical response. These include behavior; feeding rate changes; respiration rate, oxygen consumption, and osmoregulation alterations; nucleic acids, protein, and glycogen synthesis; cholinesterase activity inhibition; ATPase activity; and oxidative stress responses. This paper also deals with residues of antibiotics and pesticides in penaeid shrimp. Antibiotics and pesticides used in aquaculture may have adverse effects on treated animals and human consumers health if they are not correctly used. As a complement to the measurement of antibiotic and pesticide residues in tissues, the use of behavioral and biomarker responses can provide more relevant biological information on the potential adverse effects of antibiotics and pesticides on penaeid shrimp health. Environ. Toxicol. Chem. 2010;29:929–938. © 2009 SETAC