bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid assessment of induced cytochrome P4501 a protein and catalytic activity in fish hepatoma cells grown in multiwell plates: Response to TCDD, TCDF, and two planar PCBS
Authors: Hahn Mark E. , Woodward Bonnie L. , Stegeman John J. , Kennedy Sean W.
Published: March 2010

Induction of cytochrome P4501A1 (CYP1A1) in cultured cells can be used to determine taxon-specific relative potencies of Ah receptor agonists. This report describes optimized methods for growth and treatment of PLHC-1 fish hepatoma cells in multiwell plates, in situ analysis of ethoxyresorufin O -deethylase (EROD) activity, and measurement of CYP1A protein by immunoblotting of cell lysates. EROD activity was undetectable (<1 pmol min−1 mg−1) in untreated or dimethyl sulfoxide-treated cells, but was highly induced (up to 150 pmol min−1 mg−1) in cells exposed to Ah receptor agonists such as 2,3,7,8–tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8–tetrachlorodibenzofuran (TCDF), or planar chlorobiphenyls (CB). Addition of exogenous NADPH was not required for measurement of EROD activity in PLHC-1 cells. As inducers of EROD activity, TCDD, TCDF, 3,3′,4,4′,5– pentachlorobiphenyl (CB-126), and 3,3′,4,4′-tetrachlorobiphenyl (CB-77) differed both in potency and in apparent efficacy (maximal level of induced activity). In each case, EROD induction was biphasic, with stronger induction at lower concentrations and an attenuated response at higher concentrations. In contrast, the content of immunodetectable CYP1A protein increased monotonically with dose of CB, and the maximum level achieved was similar for all inducers. The discrepancy in results obtained for EROD activity versus CYP1A protein may result from inhibition or inactivation of catalytic function at high concentrations of inducer. By reducing peak EROD values, this inhibition leads to lower apparent EC50 values and thus the overestimation of relative potencies or toxic equivalency factors (TEFs) for many inducers. These studies demonstrate the necessity of measuring both EROD activity and immunodetectable CYP1A protein for the accurate assessment of CYP1A induction and relative potencies in cultured cells.
Evaluating macroinvertebrate population and community level effects in outdoor microcosms: Use of in situ bioassays and multivariate analysis
Authors: Shaw Jennifer L. , Manning Jeffrey P.
Published: March 2010

Evaluating toxicant effects on aquatic communities is difficult due to the ecological complexity at higher levels of organization. Two methods were assessed to improve the understanding of effects on macroinvertebrate communities in aquatic model ecosystems. First, in situ bioassay population effects were used to interpret effects at a higher organization level. Second, canonical discriminant analysis was used to investigate effects on community structure. In situ bioassays were conducted on six occasions in 17-m3 microcosms treated with copper sulfate. Macroinvertebrates occurring naturally in the microcosms were monitored. Epibenthic in situ bioassays were conducted using Caenis sp. (Ephemeroptera) and Hyalella azteca (Amphipoda) and a water column bioassay was conducted using Notonectidae (Hemiptera). Survival and growth were assessed after 3 d. Effects of copper on both Notonectidae and Caenis were observed following application. However, the final Caenis epibenthic bioassays indicated that potential for recovery and survival was ≥95%. Potential for recovery was less distinct in the water column bioassays. Copper effects also occurred on epibenthic macroinvertebrate populations and communities. Only four taxa, including Caenis, distinguished community differences among copper treatments soon after application. Later, communities showed similarities to the pretreatment bioassay. However, actual recovery was less apparent than the potential for recovery indicated by the bioassays, and community differences due to Caenis persisted.
Development of an anaerobic sludge respiration inhibition test and its use to assess septic tank safety of consumer products
Authors: Vaishnav Dinesh D. , McCabe James W.
Published: March 2010

A 6-h laboratory test protocol was developed to assess the potential effect of consumer products on anaerobic sludge respiration in septic tanks. Respiration was measured in terms of the amount of gases produced by sludge microbes from cellulose degradation at about 21°C. The optimum test conditions for maximum gas production were determined to be: (1) 10 to 20 g (dry wt.) of sludge per liter was adequate and sludge could be stored at 2 to 4°C for up to 4 d, (2) 2.5 to 5 g of cellulose substrate per liter was sufficient, and (3) 25 ml of modified synthetic sewage feed per liter provided trace levels of nutrients. The protocol was used to develop the sodium chloride reference toxicity test. The 96-h EC50s of sodium chloride for anaerobic sludge were between 3.5 and 10 g/L. The protocol was also used to test four consumer products to assess their safety to sludge microbes in septic tanks. The 24- to 96-h EC50s and 96-h no-observed-effect concentrations (NOECs) of test products were calculated. The potential effect of one of the products, a laundry dry bleach, on sludge microbes in a septic tank was assessed using the NOEC value.
Mercury pathways in the carson river—lahontan reservoir system, nevada, usa
Authors: Bonzongo Jean-Claude J. , Lyons W. Berry , Heim Kenneth J. , Chen Y Uan , Warwick John J. , Miller Glenn C. , Lechler Paul J.
Published: March 2010

Concentrations of mercury (Hg) were determined in surface waters and associated river bank sediment samples in a river—reservoir system contaminated by mine wastes. The distribution of total and methyl Hg in surface waters along the Carson River was similar to that measured in river bank sediments and influenced by flow regimes. High levels of Hg (up to 7,585 and 7.2 ng Hg/L for total and methyl Hg, respectively) determined on surface water samples were in large part discharged from Hg-contaminated tailings, distributed in the river bank sediments. Once introduced into the river during the spring snowmelt runoff, Hg was transported downstream and accumulated in the lacustrine part of the system. Elemental Hg (Hg0) increased from 0.02 ng/L in the noncontaminated region to about 2 ng/L in the reservoir. The vertical distribution of total methylmercury (MeHgT) in water of the reservoir differs from that observed elsewhere, in both Hg-contaminated and noncontaminated lakes. The highest levels of MeHgT (<1 ng/L as Hg) and acid-reactive Hg (4 ng/L) were observed in the alkaline and oxic surface waters. The decrease of pH with depth and the absence of oxygen in depth >10 m did not enhance MeHg production. In the anoxic hypolimnion of the reservoir, the recycling of MeHgT was more influenced by the redox cycling of Mn. The addition of group VI anions (SeO2−4, MoO2−4, and WO2−4) in the range of concentrations of oxyanion-forming elements found in the Carson River system to anoxic sediment slurry spiked with SO2−4 resulted in the reduction of rates of MeHg production. Their negative effect on MeHg production was enhanced by increasing pH. Group VI anions, analogous to SO2−4 are inhibitory to sulfate-reducing bacteria, which are known to play a key role in MeHg production in anoxic sediments. Accordingly, the particular water geochemistry of the Carson River system could partly explain the observed low levels of MeHg where one would expect higher concentrations.
Relative mobilities of atrazine, five atrazine degradates, metolachlor, and simazine in soils of iowa
Authors: Kruger Ellen L. , Coats Joel R. , Zhu B Eilei
Published: March 2010

The relative mobilities of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), five atrazine degradates, metolachlor (2-chloro-N-[2-ethyl-5-methylphenyl]-N-[2-methoxy-1-methylethyl]-acetamide), and simazine (2-chloro-4,6-bis-[ethylamino]-s-triazine) were determined in both surface and subsurface soils from five locations in Iowa by soil thin-layer chromatography (STLC). Based on mobility of the compounds, four groups were identified from this study. Deethylatrazine (2-chloro-4-amino-6-isopropylamino-s-triazine) was the most mobile compound. The intermediate mobility group included atrazine, deisopropylatrazine (2-chloro-4-ethylamino-6-amino-s-triazine), and didealkylatrazine (2-chloro-4,6-diamino-s-triazine). The less mobile group included metolachlor and simazine, and the nearly immobile group consisted of ammeline (4,6-diamine-s-triazine-2-ol) and hydroxyatrazine (2-hydroxy-4-ethylamino-6-isopropylamino-s-triazine). A clear division between the intermediate and less mobile group was not seen in all soils. Mobilities of all eight compounds in this study were negatively correlated with soil organic matter content (p ≤ 0.05) and positively correlated (except for didealkylatrazine) with sand content (p ≤ 0.05). The greatest degree of mobility for the compounds studied was seen in Fruitland (sandy) and Nashua (sandy clay loam) subsurface soils, which also had the least organic matter contents. The mobility relationship of atrazine, deethylatrazine, and deisopropylatrazine in this study (deethylatrazine ≥ atrazine ≥ deisopropylatrazine) is consistent with groundwater monitoring reports. Similar mobilities of atrazine, deisopropylatrazine, and didealkylatrazine in some soils of this study suggest that didealkylatrazine is mobile enough to reach groundwater and therefore should be looked for in routine monitoring.
A toxicity test in artificial soil based on the life-history strategy of the nematode Plectus acuminatus
Authors: Kammenga Jan E. , Van Koert Paul H.G. , Riksen Joost A.G. , Korthals Gerard W. , Bakker J.
Published: March 2010

The ecological risk assessment of toxicants in soil requires reproducible and relevant test systems using a wide range of species. To supplement present test methods from the Organisation of Economic Cooperation and Development (OECD) in artificial soil with earthworms and springtails, a toxicity test in OECD artificial soil has been developed using the bacterivorous nematode Plectus acuminatus (Bastian, 1865) (Nematoda; Plectidae). The juvenile to adult ratio was used as a test parameter since previous life-cycle studies pointed out that fitness of P. acuminatus was strongly determined by changes in both reproduction and juvenile survival. Optimal conditions for the performance of nematodes in OECD artificial soil were determined (pHKCl = 5.5, temperature = 20°C, and a moisture content of 70% dry wt. artificial soil), and tests were conducted with cadmium, copper, and pentachlorophenol. After an exposure period of 3 weeks the EC50 for cadmium was 321.0 ± 1.7 mg/kg dry wt., and the no-observed-effect concentration (NOEC) was 32 mg/kg dry wt. The EC50 for pentachlorophenol was 47.9 ± 1.2 mg/kg dry wt., and the NOEC was <10 mg/kg dry wt. For copper the EC50 was 162 ± 0.2 mg/kg dry wt., and the NOEC was 32 mg/kg dry wt. It is concluded that the nematode test may well supplement current soil test systems using earthworms and springtails.
Inhibition of cytochrome p4501a by organotins in fish hepatoma cells plhc-1
Authors: Brüschweiler Beat J. , Fent Karl , Würgler Friedrich E.
Published: March 2010

Inhibitory effects of several organotin compounds on cytochrome P4501A (CYP1A) induction response and enzyme activity have been analyzed in fish hepatoma cells (PLHC-1). In a first set of experiments, cells were exposed for 3 d to 3-methylcholanthrene (3-MC), an inducer of CYP1A. Simultaneously, series of dilutions of the widely used organotin compounds triphenyltin (TPT), tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) were added to the cells. Relative CYP1A protein contents were measured in an enzyme-linked immunosorbent assay (ELISA), CYP1A activities in the ethoxyresorufin-O-deethylase (EROD) assay, and cytotoxicity in the neutral red (NR) assay. Induction of CYP1A protein and activity was found in the presence of low concentrations of organotins and 3-MC. The three assays did not show significant differences in sensitivity for TBT and TPT. Concentrations that reduced control values by 50% (EC50) were between 1.6·10−7 M and 3.5·10−7 M, which emphasizes the high cytotoxicity of both compounds. In contrast, DBT led to inhibition of EROD activity at significantly lower concentrations (1.2·10−6 M) than loss of CYP1A protein in the ELISA (9.0·10−6 M) and cytotoxicity in the NR assay (8.7·10−6 M). In a second set of experiments, reduction of CYP1A activity was also obtained after sequential exposure to 3-MC and organotins. In a third set of experiments, lysates of CYP1A-induced cells were exposed to organotins. Organotins caused a 50% inhibition of EROD activity at significantly higher concentrations (namely at 4.7·10−5 M and 6.7·10−5 M for TBT and DBT, respectively, and at 1.1·10−3 M for MBT) than in the first set of experiments. For TBT, a noncompetitive inhibitory mechanism on CYP1A enzyme activity has been found. The experiments in this study demonstrate inhibitory capacities of TBT and TPT, but also of DBT and MBT, on the CYP1A system in fish cells. The results lead to the conclusion that the effect is mainly caused by direct inhibition of enzyme activity, not by inhibition of CYP1A protein synthesis. The induction of CYP1A protein and activity in the presence of both an inducer (3-MC) and a low concentration of inhibitors (organotins) indicates that organotins do not interfere with the Ah receptor binding, but act at the CYP1A protein level.
Evaluation of the developmental toxicity of the pesticide mcpa and its contaminants phenol and chlorocresol
Authors: Bernardini Giovanni , Spinelli Orietta , Vismara Claudio , Presutti Cecilia , Bolzacchini Ezio , Orlandi Marco , Settimi Raffaella
Published: March 2010

The embryotoxicity of 4-chloro-2-methylphenoxyacetic acid (MCPA), an extensively used herbicide, has been evaluated and compared to that of phenol and chlorocresol (two common contaminants) with a bioassay that makes use of embryos of the amphibian Xenopus. The MCPA—Na salt used in the bioassay was purified by crystallization and acid-base purification methods, and the concentrations of phenol and chlorocresol were checked by high-performance liquid chromotography. The relationship between the concentration of the tested molecule and the outcomes (i.e., mortality and malformations) was investigated using different models (probit, logit, and complementary log-log). The resulting LC50s for MCPA, chlorocresol, and phenol are 3,607, 13, and 178 mg/L, respectively; the resulting LC10s are 1,526, 6, and 32 mg/L. It is evident that the real MCPA toxicity can be masked by the presence of contaminants much more toxic than the molecule studied. Moreover, our results show that the three chemicals do not present a high teratogenic risk. Growth retardation shows that MCPA, chlorocresol, and phenol are effective at concentrations as low as 2,000, 2.5, and 25 mg/L, respectively.
Bacterial interference in whole-effluent toxicity tests
Authors: Grothe Donald R. , Johnson Daniel E.
Published: March 2010

Routine National Pollutant Discharge Elimination System (NPDES) cooling-water toxicity tests demonstrated an acute effect on Ceriodaphnia dubia and fathead minnows (Pimephales promelas). Test results were characterized by irregular mortality dose-response curves and a brown filamentous mass on the opercular area of affected fish. Some fish and Ceriodaphnia also became entrapped in filamentous material present on the bottom of the test vessels. Microscopic examination of test fish revealed severe fouling of the oral and branchial cavities with a mixed population of microbes, the major component being a filamentous sheathed bacteria. Treatment of water samples with a 0.45-μm membrane filter and/or ultraviolet light sterilizer were effective in eliminating the bacteria and test organism mortalities. Regulatory test procedures were modified to allow filtration of the water prior to testing to eliminate this naturally occurring biological interference in toxicity tests.
Effects of nutritional renewal frequency on survival and reproduction of Ceriodaphnia dubia
Authors: Ferrari Benoit , Ferard Jean-François
Published: March 2010

Different renewal diet frequency procedures of Ceriodaphnia dubia were evaluated with different culture stages: intervening cultures and pilot tests (equivalent to controls in a classical toxicity test). A series of control experiments was conducted on over three generations to estimate historical culture influence and effects of different renewal frequencies in five different factorial designs performed at different times. The criteria to assess health of culture were survival and reproduction. Nutritional deficiency was not found during this study, but renewal frequency has an obvious effect on the reproduction. This study further establishes that a medium slightly different than those recommended by the U.S. Environmental Protection Agency can successfully work for culturing and testing C. dubia.
DNA strand breakage in freshwater mussels (Anodonta grandis) exposed to lead in the laboratory and field
Authors: Black Marsha C. , Ferrell Jennifer R. , Horning Renée C. , Martin Larry K.
Published: March 2010

The sensitivity of a freshwater mussel, Anodonta grandis, to DNA damage following lead (Pb) exposure was tested in laboratory and field experiments. Laboratory exposures were conducted for 4 weeks at the following Pb concentrations: 0 (controls), 50, 500, and 5000 μg/L. Mussels were also collected from a strip-mine pond contaminated with trace amounts of lead, cadmium (Cd), and zinc (Zn). Significant DNA strand breakage was observed in foot tissue from mussels exposed in the laboratory to the lowest Pb concentration (50 μg/L). No evidence of strand breakage was observed in any of the analyzed tissues from the mussels exposed to higher Pb concentrations (500 and 5000 μg/L) or from the chronically exposed mussels collected from the strip-mine pond. These data suggest a threshold effect for DNA damage and repair resulting from low-level Pb exposure, whereby repair of DNA strand breaks may occur only if a certain body burden or exposure duration has been achieved.
In vitro induction of CYP1A1-associated activities in human and rodent cell lines by commercial and tissue-extracted halogenated aromatic hydrocarbons
Authors: Vamvakas Andreas , Keller Jason , Dufresne Michael
Published: March 2010

Despite reports of species-specific differences, the rat cell line H4IIE continues to be used to assess the toxicity of many halogenated aromatic hydrocarbon (HAH) contaminants for diverse populations using an approach that relates aryl hydrocarbon (Ah) receptor-mediated responses by HAHs to that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). To assess the relevance of H4IIE for human populations, we examined levels of aryl hydrocarbon hydroxylase (AHH) and ethyoxyresorufin O-deethylase (EROD) activities in H4IIE rat liver, HepG2 human liver, and MCF-7 human breast cells treated with TCDD and three coplanar polychlorinated biphenyl (PCB) congeners (77, 126, 169), alone or in combination, and to fractions extracted from the muscle tissue of Lake Ontario rainbow trout (Oncorhynchus mykiss). H4IIE was generally more sensitive to all HAH treatments. Both AHH and EROD activities were induced in all cells treated with TCDD and PCB-126, alone or combined with each other. In contrast, neither activity was induced in human cells treated with PCB-77 or PCB-169. For inducing concentrations of PCBs, the induction response in all cell lines treated with 5 nM TCDD-PCB mixtures was generally nonadditive; only the response in H4IIE treated with 10−3 nM TCDD–PCB mixtures was generally additive. With tissue extracts, induction was restricted to H4IIE cells treated with TCDD/PCB-or organochloride pesticide-containing fractions. Our initial results suggest that differences in the properties of each HAH or in levels of Ah receptor in each cell line are not likely to underlie the significant differences in the murine/human induction responses.
Development of procedures for identifying pesticide toxicity in ambient waters: Carbofuran, diazinon, chlorpyrifos
Authors: Bailey Howard C. , Digiorgio Carol , Kroll Kevin , Hinton David E. , Miller Jeffrey L. , Starrett Gwen
Published: March 2010

The responses of carbofuran, diazinon, and chlorpyrifos to standard acute toxicity identification evaluation (TIE) procedures were characterized. The test species was Ceriodaphnia dubia. The TIE procedures included solid-phase extraction, recovery in methanol eluates, hydrolysis under acid and base conditions, and retention in specific methanol/water fractions. In addition, the effect of the metabolic inhibitor, piperonyl butoxide, on the toxicity of each of the pesticides was determined. Diazinon degraded quickly under acid conditions, whereas carbofuran degraded under base conditions. In both cases, concentrations were reduced to nontoxic levels within 6 h. Conversely, acidic or basic conditions were not effective in reducing the concentration of chlorpyrifos over the same time period. Solid-phase extraction removed at least 95% of diazinon and carbofuran from solution, but was less effective with chlorpyrifos. All three pesticides eluted separately in characteristic methanol/water fractions. Piperonyl butoxide ameliorated the toxicity of diazinon and chlorpyrifos, but not carbofuran. Up to 1.5% methanol did not interfere with the protective action of piperonyl butoxide. Case studies in which these techniques were applied to ambient water samples are also described.
Persistence of white phosphorus (P4) particles in salt marsh sediments
Authors: Walsh Marianne E. , Collins Charles M. , Racine Charles H.
Published: March 2010

Remediation of sediments at Eagle River Flats, Alaska, a salt marsh contaminated with solid particles of white phosphorus (P4), may require severe alterations of the wetland by dredging, draining, or covering. However, some sediments may undergo decontamination naturally in areas that are seasonally subaerially exposed. The persistence of millimeter-size P4 particles was studied in laboratory and field experiments. White phosphorus particles were found to be persistent in saturated sediments. In unsaturated sediments, loss was rapid (within 24 h) at 20°C, and was retarded by low temperatures.
Uptake of cesium-134 by the earthworm species Eisenia foetida and Lumbricus rubellus
Authors: Janssen Martien P. M. , Glastra Peter , Lembrechts Johan F. M. M.
Published: March 2010

The uptake processes of 134Cs in two earthworm species were investigated as well as the effect of temperature on these processes. The results show that equilibrium concentrations in the two species differ by 1.5-to fivefold. Equilibrium concentrations range from 367 to 963 Bq g−1 in Lumbricus rubellus and from 920 to 1,893 Bq g−1 in Eisenia foetida; biological half-lives range from 56 to 119 h and 52 to 64 h, respectively. Assimilation was two to four times higher in E. foetida and elimination rate one to two times higher in E. foetida than in L. rubellus. Further, the results show that temperature may affect the 134Cs concentration in these earthworms by a factor of 1.4 to 2.1 between 10 and 20°C, depending on the species. The maximum difference found within one species was a factor of 2.6. Our results show no clear effect of temperature on the assimilation, but a small negative effect on elimination, resulting in an increasing biological half-life and concentration factor with higher temperatures.
Bioaccumulation, metabolism, and biochemical effects of the organophosphorus pesticide fenitrothion inProcambarus clarkii
Authors: Escartín Estefania , Porte Cinta
Published: March 2010

Fenitrothion (O,O-dimethyl O-(3-methyl-4-nitrophenyl) phosphorothioate) is readily taken up from the water by the crayfish Procambarus clarkii. The bioconcentration factor, however, is lower than expected on the basis of its octanol/water partition coefficient. The ability of P. clarkii to metabolize fenitrothion was evaluated in vitro by using 12,000-g supernatant or microsomal fractions isolated from hepatopancreas and the results pointed out the existence of both oxidative and glutathione-mediated metabolism. Several biomarkers of exposure viz., the microsomal mixed-function oxygenase system, a phase II enzyme [glutathione S-transferase], and acetylcholinesterase inhibition, were studied in organisms exposed to 20 μg/L of fenitrothion for 48 h. Cytochrome P450 content, NADPH cytochrome c(P450) reductase, and 7-ethoxyresorufin O-deethylase activity showed significant induction the second day of treatment, whereas glutathione S-transferase activity appeared to be unaffected. Acetylcholinesterase activity in the neuromuscular tissue of P. clarkii was a good indicator of exposure to this compound.
Long-term effects of copper and ph on the nematode community in an agroecosystem
Authors: Korthals Gerard W. , Bongers Tom , Kammenga Jan E. , Alexiev Alexey D. , Lexmond Theo M.
Published: March 2010

Four copper (0, 250, 500, and 750 kg Cu · haa−1) and pH (4.0, 4.7, 5.4, and 6.1 in 1 M KCl) treatments were applied to an arable agroecosystem. Effects on the nematode community were assessed after 10 years of exposure under field conditions. Both copper and pH had major influences on nematodes. The effect of copper was generally enhanced with decreasing soil pH. The lowest copper application rate which had a significant negative effect on the total number of nematodes was 250 kg. ha−1 at pH 4.0, which is equivalent to a copper concentration of 0.32 mg.L−1 in 0.01 M calcium chloride (Cu-CaCl2). Species composition and the abundance of trophic groups were more sensitive than the total number of nematodes. Combinations of high copper and low pH significantly reduced the number of bacterial-feeding nematodes, whereas the number of hyphal-feeding nematodes increased. Omnivorous and predacious nematodes showed the most sensitive response, becoming extinct when Cu-CaCl2 was 0.8 to 1.4 mg.L−1. Plant-feeding nematodes showed the largest differences in abundance and appeared to reflect the effects of copper and pH on primary production. The results suggest that the nematode community was also affected indirectly by copper and pH via other components of the soil food web. It is concluded that nematodes offer excellent perspectives to assess effects of pollutants at the community level.
Physicochemical changes of aluminium in mixing zones: Mortality and physiological disturbances in brown trout (Salmo trutta L.)
Authors: Witters Hilda E. , VanPuymbroeck Sylvain , Stouthart Alexander J. H. X. , Bonga Sjoerd E. Wendelaar
Published: March 2010

A standardized laboratory setup, smulating field mixing zones that originate at the confluence of limed rivers with acidic, aluminium-rich, tributaries, has been developed. Detailed analyses of the chemical speciation of aluminium (Al) in relation to the biological response of brown trout were performed to identify the mechanism of unexpected high fish mortality in the above-mentioned mixing zones with pH levels above 6.0. Brown trout experienced an acute cumulative mortality (98% in 48 h) immediately afterneutral and acidic, Al-rich, water had mixed. Mortality was only 60% within 48 h of exposure to the acid water with Al (pH 4.6 +6.8 μmol Al/L), although the Al concentration in the mixing zone was less (2.8 μmol Al/L) at a nonharmful pH level (pH 6.4). Chemical speciation and ultrafiltration studies demonstrated that the transformation of low-molecular weight Al (<10 kD) into high-molecular weight Al (> 10 kD), defined as Al polymerization, could better be related to the toxic response offish, than the total Al concentration. The aging of polymerized Al forms (for 480 s) resulted in reduced fish mortality and less pronounced physiological stress. Brown trout in the initial mixing zone showed significantly increased plasma glucose and cortisol levels. Light and electron microscopy studies demonstrated serious damage to the skin: increased mucous secretion, a high ratio of acid to neutral glycoprotein-containing mucous cells, increased apoptosis, and infiltration of leucocytes and macrophages between the epithelial cells. Ionoregulatory parameters, which showed minor changes in fish in the initial mixing zone, did not allow explanation of acute fish mortality. Data on the ventilation frequency and the blood hematocrit, which both increased, gave support for the hypothesis that acute fish mortality in mixing zones could be caused by respiratory dysfunction.
Effects of a nonionic surfactant (c14–15 AE-7) on fish survival, growth and reproduction in the laboratory and in outdoor stream mesocosms
Authors: Kline Edward R. , Figueroa Rocio A. , Rodgers John H. , Dorn Philip B.
Published: March 2010

The effects of a nonionic surfactant (C14–15 AE-7) on survival and growth of juvenile bluegill sunfish and on survival and reproduction of fathead minnows were investigated in the laboratory and in outdoor stream mesocosms. In the laboratory, where the fish were exposed for 10 d, the 96-h LC50 values for bluegill sunfish and fathead minnows were 650 and 770 μg/L, respectively. The no-observed-effect concentration (NOEC) for survival and swimming performance of bluegill sunfish and for survival of fathead minnows was 160 μg/L. The lowest-observed-effect concentration (LOEC) for these toxic responses was 460 μg/L. In the stream mesocosms, where the fish were exposed for 30 d, the NOEC for bluegill sunfish survival and growth was >330 μg/L. The LOEC for fathead minnow survival was 330 μg/L, and the NOEC was 280 μg/L. Decreased egg laying by fathead minnows was noted in the streams at concentrations of 330 μg/L or greater. Close correspondence between the results of laboratory tests and those obtained under field conditions in the mesocosms indicates that for this surfactant, it may not be necessary to apply “safety factors” to extrapolate results from the laboratory to the field.
Congener-specific polychlorinated biphenyl patterns in eggs of aquatic birds from the lower laguna madre, texas
Authors: Mora Miguel A.
Published: March 2010

Eggs from four aquatic bird species nesting in the Lower Laguna Madre, Texas, were collected to determine differences and similarities in the accumulation of congener-specific polychlorinated biphenyls (PCBs) and to evaluate PCB impacts on reproduction. Because of the different toxicities of PCB congeners, it is important to know which congeners contribute most to total PCBs. The predominant PCB congeners were 153, 138, 180, 110, 118, 187, and 92. Collectively, congeners 153, 138, and 180 accounted for 26 to 42% of total PCBs. Congener 153 was the most abundant in Caspian terns (Sterna caspia) and great blue herons (Ardea herodias) and congener 138 was the most abundant in snowy egrets (Egretta thula) and tricolored herons (Egretta tricolor). Principal component analysis indicated a predominance of higher chlorinated biphenyls in Caspian terns and great blue herons and lower chlorinated biphenyls in tricolored herons. Snowy egrets had a predominance of pentachlorobiphenyls. These results suggest that there are differences in PCB congener patterns in closely related species and that these differences are more likely associated with the species' diet rather than metabolism. Total PCBs were significantly greater (p < 0.05) in Caspian terns than in the other species. Overall, PCBs in eggs of birds from the Lower Laguna Madre were below concentrations known to affect bird reproduction.
Modeling the nucleophilic reactivity of small organochlorine electrophiles: A mechanistically based quantitative structure-activity relationship
Authors: Verhaar Henk J. M. , Seinen Willem , Hermens Joop L. M. , Rorije Emiel , Borkent Hens
Published: March 2010

Environmental pollutants can be divided into four broad categories, narcosis-type chemicals, less inert (“polar narcosis”) chemicals, reactive chemicals, and specifically acting chemicals. For narcosis-type, or baseline, chemicals and for less inert chemicals, adequate quantitative structure-activity relationships (QSARs) are available for estimation of toxicity to aquatic species. This is not the case for reactive chemicals and specifically acting chemicals. A possible approach to develop aquatic toxicity QSARs for reactive chemicals based on simple considerations regarding their reactivity is given. It is shown that quantum chemical calculations on reaction transition states can be used to quantitatively predict the reactivity of sets of reactive chemicals. These predictions can then be used to develop aquatic toxicity QSARs.
Chronic effects of nonpolar narcotics on a model microbial community
Authors: Jaworska Joanna S. , Hallam Thomas B. , Schultz Terry W.
Published: March 2010

The dynamics of a model of a microbial batch culture community consisting of Tetrahymena pyriformis and Escherichia coli populations are explored when the community is stressed by chemicals with a nonpolar narcosis mode of action. The framework for the community consists of two individual-based population models, individual models of the organisms T. pyriformis and E. coli, and exposure and effect modules for each species. The exposure module is based on passive diffusion and describes both environmental and resource routes of exposure. The effect module utilizes quantitative structure–activity relationships to determine resource uptake reduction, the effect chosen as the primary consequence of exposure to the chemical. The range of possible effects on the model ciliate–bacterial community includes results that do not arise from population studies; for example, chemically depressed growth rates of individuals can be stimulatory for a population in a community setting. Community structure and feedback mechanisms are demonstrated to be fundamental for effects determination in that structure evolves as a function of exposure concentration. In a closed system, the presence of nonviable organic material modifies bioavailability of the toxicant and allows for community persistence above concentration levels that cause mortality in a continuous culture. An indicator of stress, the community extinction threshold, is developed as a function of chemical diffusivity and hydrophobicity.
DNA damage and radiocesium in channel catfish from chernobyl
Authors: Sugg Derrick W. , Brooks Janet A. , Jagoe Charles H. , Smith Michael H. , Chesser Ronald K. , Bickham John W. , Lomakin Michael D. , Dallas Cham E. , Baker Robert J.
Published: March 2010

The explosion of the Chernobyl Nuclear Power Plant resulted in some of the most radioactively contaminated habitats on earth. Despite evacuation of all human inhabitants from the most contaminated areas, animals and plants continue to thrive in these areas. This study examines the levels of contamination and genetic damage associated with radiocesium in catfish (Ictalurus punctatus) from the cooling pond and a control site. In general, catfish from the cooling pond exhibit greater genetic damage, and the amount of damage is related to the concentration of radiocesium in individual fish. Genetic damage is primarily in the form of DNA strand breaks, with few micronuclei being observed in contaminated fish. The possible roles that acclimation and adaption play in the response to high levels of radiation exposure are discussed.
Hydrolysis of carbon tetrachloride
Authors: Jeffers Peter M. , Brenner Christine , Lee Wolfe N.
Published: March 2010

New experimental data on the hydrolysis of dilute solutions of carbon tetrachloride (CCl4) indicate clearly that the reaction is first–order in CCl4, a conclusion contrary to the classic work of Fells and Moelwyn-Hughes. These historical data have been reanalyzed and shown to be consistent with first-order kinetics. A new determination of the Arrhenius parameters confirm an environmental half-life of 40 years for CCl4.
A Test of sediment effects concentrations: DDT and PCB in the southern california bight
Authors: Chapman Peter M.
Published: March 2010

Independent efforts to determine concentrations of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethanes (DDTs) along the Southern California Bight which result in adverse biological effects resulted in similar values. A correlative approach using historic data calculated the following likely sediment effects concentrations: total DDTs, 7.12 mg/dry kg (199 mg/kg organic carbon [OC]); and total PCBs, 0.592 mg/dry kg (30.4 mg/kg OC). Testing of field-collected sediments yielded the following no-observed-effect concentrations based on full life-cycle testing: total DDTs, 8.51 mg/dry kg (269 mg/kg OC); and total PCBs, 1.07 mg/dry kg (36.6 mg/kg OC).
Characterization of mussel beds with residual oil and the risk to foraging wildlife 4 years after the Exxon valdez oil spill
Authors: Boehm Paul D. , Mankiewicz Paul J. , Reilly James E. O. , Hartung Rolf , Neff Jerry M. , Page David S. , Gilfillan Edward S. , Parker Keith R.
Published: March 2010

The grounding of the Exxon Valdez on March 24, 1989, released about 41 million L of crude oil into the waters of Prince William Sound, Alaska, USA, and oiled about 16% of the Prince William Sound shoreline to various degrees. Although winter storms, cleanups, and natural biodegradation have removed the majority of the oil on the shorelines, some residual oil still remains trapped in sediments immediately below mussel beds. This oil was protected from wave action by the dense covering of mussels. Field surveys found that mussels in such beds constituted less than 3% of the mussels available for foraging in two areas that had been extensively oiled in 1989. Levels of polycyclic aromatic hydrocarbons (PAHs) in these mussels were also measured. Mean PAH concentrations in mussel tissues ranged between 20 and 4,000 ng/g dry weight and in sediments between 20 and 26,000 ng/g dry weight. Assuming that the species considered most at risk (i.e., harlequin ducks, black oystercatchers, and sea otters) consumed the mussel proportion of their diets exclusively from such beds (at either the median or 95th percentile of mussel tissue PAH concentration), the estimated PAH dosage they would receive was one to three orders of magnitude below doses known to cause sublethal effects in surrogate species. Considering the low frequency of mussel beds with residual oil, the patchy distribution of remaining weathered oil residues, and the relatively low PAH concentrations in the mussels, the risk of quantifiable injury at the level of an individual bird or otter, or at the population level, is minimal. Furthermore, based on a review of the mussel PAH data in Prince William Sound, the risk to wildlife has been minimal since 1990, 1 year after the spill.
Acute and subchronic toxicity of methylene blue to larval fathead minnows (Pimephales promelas): Implications for aquatic toxicity testing
Authors: Rifici Louis M. , Cherry Donald S. , Farris Jerry L. , Cairns John
Published: March 2010

The acute and 7-d subchronic toxicity of methylene blue were determined for fathead minnow larvae using U.S. Environmental Protection Agency methods. The 96-h lethal concentration (LC50) was 45 and 15 mg/L at 20 and 25°C, respectively. The 7-d chronic value for survival under laboratory light and low light was the same (2.1 mg/L). However, under laboratory light, larval growth was impaired at lower concentrations (chronic value = 0.6 mg/L) than under low light (chronic value = 2.1 mg/L). To assess prior methylene blue treatment on larval sensitivity, embryos, larvae <24 h old, and embryos followed by larvae were treated with 3 mg/L methylene blue. Cadmium LC50 values were similar between methylene blue-treated and untreated control groups. When larvae treated with methylene blue as embryos were subchronically exposed to an effluent, survival was similar to that of the untreated group. However, dry weight of the treated larvae was significantly lower. Differences in dry weight between treated and untreated groups were reduced as the age of the larvae at test initiation increased. Treatment of incubating embryos using 3 mg/L methylene blue does not appear to affect larvae sensitivity to cadmium but may affect the growth of larvae used in subchronic testing.
Interlaboratory study of precision:Hyalella aztecaandChironomus tentansfreshwater sediment toxicity assays
Authors: Burton G. Allen , Norberg-King Teresa J. , Benoit Duane A. , Ankley Gerald T. , Winger Parley V. , Kubitz Jody , Lazorchak James M. , Smith Mark E. , Call Daniel J. , Ingersoll Christopher G. , Greer Eugene , Dwyer F. James , Day Kristin E. , Kennedy Paul , Stinson Margaret
Published: March 2010

Standard 10-d whole-sediment toxicity test methods have recently been developed by the U.S. Environmental Protection Agency (EPA) for the amphipod Hyalella azteca and the midge Chironomus tentans. An interlaboratory evaluation of method precision was performed using a group of seven to 10 laboratories, representing government, academia, and environmental consulting firms. The test methods followed the EPA protocols for 4-d water-only reference toxicant (KCl) testing (static exposure) and for 10-d whole-sediment testing. Test sediments included control sediment, two copper-containing sediments, and a sediment contaminated primarily with polycyclic aromatic hydrocarbons. Reference toxicant tests resulted in H. azteca and C. tentans median lethal concentration (LC50) values with coefficents of variation (CVs) of 15.8 and 19.6%, respectively. Whole sediments which were moderately contaminated provided the best estimates of precision using CVs. Hyalella azteca and C. tentans tests in moderately contaminated sediments exhibited LC50 CVs of 38.9 and 13.5%, respectively. The CV for C. tentans growth was 31.9%. Only 3% (1 of 28) of samples exceeded acceptable interlaboratory precision limits for the H. azteca survival tests. No samples exceeded the intralaboratory precision limit for H. azteca or C. tentans survival tests. However, intralaboratory variability limits for C. tentans growth were exceeded by 80 and 100% of the laboratories for a moderately toxic and control sample, respectively. Interlaboratory variability limits for C. tentans survival were not exceeded by any laboratory. The results showed these test methods to have relatively low variance and acceptable levels of precision in interlaboratory comparisons.
Nontarget effects of a test application of diflubenzuron to the forest canopy on stream macroinvertebrates
Authors: Hurd Martin K. , Perry Sue A. , Perry William B.
Published: March 2010

Forest application of diflubenzuron (DFB) is commonly used in mid-Atlantic states for control of gypsy moths in hardwood forests. To assess effects of the pesticide on nontarget organisms, DFB (Dimilin) was applied by helicopter on May 16, 1992, to two watersheds in the Fernow Experimental Forest near Parsons, West Virginia. To determine if aquatic macroinvertebrates were affected by the aerial spray, we monitored streams in two reference and two treatment watersheds before and after treatment with DFB using a multilevel artificial substrate sampler. The before-after-control-impact-pairs (BACIP) analysis was used to test for differences in aquatic macroinvertebrate densities between treated and reference watersheds. Densities of some taxa in DFB-treated watersheds either showed population depressions or did not increase in density after drought conditions as compared with those taxa in streams in reference watersheds, whereas other taxa increased in treated watersheds. Taxa that had reduced mean densities in treatment watersheds (α = 0.05) included the stoneflies, Leuctra sp. and Isoperla sp., the mayfly, Paraleptophlebia sp., and the crane fly, Hexatoma sp. Shredders, the dominant functional feeding group, also had reduced mean densities in treatment watersheds. Densities of Oligochaeta and Turbellaria increased in streams in treated watersheds.
Size-dependent response of macroinvertebrates to metals in experimental streams
Authors: Kiffney Peter M. , Clements William H.
Published: March 2010

Our previous research has shown that the effects of metals on stream benthic invertebrate populations and communities can vary within and between locations. With this in mind, we examined whether invertebrate body size could explain some of the variation in metal sensitivity within a species. Benthic macroinvertebrates from a pristine Rocky Mountain foothills' stream were collected using artificial substrates and exposed to a mixture of Cd, Cu, and Zn in stream microcosms for 10 d at their respective Colorado chronic criterion levels (4.0, 5.0, and 50 μg/L). The effects of metals on the ephemeropterans Baetis tricaudatus (Baetidae), Ephemerella infrequens (Ephemerellidae), and Rhithrogena hageni (Heptageniidae) and the plecopteran Pteronarcella badia (Pteronarcyidae) were size dependent, as there was an inverse relationship between body size and survivorship. These results may have important implications for setting water-quality criteria for metals and for using benthic invertebrates in biological assessments.
Effects of in vitro exposure of beluga whale splenocytes and thymocytes to heavy metals
Authors: Bernier Jacques , Fournier Michel , De Guise Sylvain , Martineau Daniel , Beland Pierre
Published: March 2010

The effects of in vitro exposure of beluga whale splenocytes and thymocytes to different concentrations of mercury chloride (HgCl2), cadmium chloride (CdCl2), and lead chloride (PbCl2) were evaluated. The cells were cultured for 66 h with either concanavalin A (Con-A), phytohemagglutinin-P, or without mitogen, after which percentage of cell death and proliferation were evaluated. Increased percentage of cell death was observed in Con-A-stimulated thymocytes cultured with HgCl2, while the viability of splenocytes was not affected by exposure to metals. Decreased splenocyte and thymocyte proliferation was observed with the highest concentration of HgCl2 and CdCl2 (10−5 M), while lower concentrations of these metals (10−6 and 10−7 M) as well as all the different concentrations of PbCl2 (10−4, 10−5, and 10−6 M) did not significantly influence cell proliferation. Concentrations of metals that were found to affect the proliferation of beluga lymphocytes are similar to those found in the liver of beluga whales from wild populations.
Organochlorine dynamics in the pelagic food web of lake baikal
Authors: Kucklick John R. , Harvey H. Rodger , Baker Joel E. , Ostrom Peggy H. , Ostrom Nathaniel E.
Published: March 2010

In July and August 1993, samples were collected from Lake Baikal both to document organochlorine concentrations and to relate the contaminant levels to trophic position and lipid concentration. High-volume water samples and representatives of the major organisms in the food web, including zooplankton, fish, and seals, were collected. Dissolved and particulate water samples were analyzed for polychlorinated biphenyls (PCBs; 74 congeners) and hexachlorobenzene. Biota samples were analyzed for PCBs, hexachlorocyclohexanes, chlordane and related compounds, dieldrin, dichlorodiphenyltrichloroethane (plus metabolites), and toxaphene. Specific lipid classes were measured in fish since these were postulated to affect organochlorine concentrations. Stable nitrogen (815N) and carbon (813C) isotopic compositions were determined in all samples except seal blubber as a measure of trophic position. Total PCBs in surface water ranged from 130 pg/L in the lake's northern basin to 1,900 pg/L in the southern basin. Total PCBs in fish ranged from 60 to 710 ng/g (wet weight), with differences mostly attributed to total lipid content rather than to specific lipid classes. The PCB bioaccumulation factor was significantly correlated with log Kow, whereas the PCB bioconcentration factor was not. The transfer of contaminants through the food web was likely at steady state, whereas the uptake of PCBs from the water was not. This indicates recent PCB contamination.