bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure-Activity relationships in environmental toxicology and chemistry: Narcosis, electrophile and proelectrophile toxicity mechanisms: Application of SAR and QSAR
Authors: Lipnick Robert L. 
Published: March 2010

AbstractA historic account is provided of the development of quantitative structure‒activity relationships (QSARs) for the toxicity of simple nonelectrolyte organic compounds. The aquatic toxicity of many such compounds has been shown to be consistent with a narcosis mechanism involving pseudo‒steady‒state partitioning into a lipoidlike biophase site of action. These data are well fitted to a linear QSAR model involving solely the log P parameter.The toxicity of such nonelectrolytes administered by inhalation yields a linear QSAR based on the oil/gas partition coefficient. In contrast, the toxicity of these substances produced by nonequilibrium routes of administration, such as rat oral LD50, yields a parabolic or bilinear relationship consistent with observations published by Cros in France in 1863. Electrophile toxicants capable of forming covalent adducts with biochemical target molecules are more toxic than predicted by the corresponding narcosis models. Proelectrophile toxicants, which require metabolic activation to electrophiles, are also more toxic than would be predicted by narcosis QSARs.
Competitive binding of chlorinated azobenzenes to the Ah receptor protein
Authors: Bunce Nigel J. , M. Choong Douglas K. , Landers James P. , Zacharewski Tim R. 
Published: March 2010

AbstractSubstituted azobenzenes bind to the aryl hydrocarbon receptor protein about one to two orders of magnitude less strongly than does 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) when they carry substituents at some of the positions 2, 3, and 4 of the benzene rings. Positions 5 and 6 are disfavored. The results are interpreted in terms of the stability of azobenzene conformers and the extent to which the azobenzenes under study are isosteric with TCDD.
Structure-Activity for uptake and toxicity of DDT-type insecticides utilizing an NMR method for estimating σ*
Authors: Coats Joel R. , Williams John W. , Chang Carolyn , Lee An-Horng , Metcalf Robert L. 
Published: March 2010

Abstract
Structure-activity relationships were examined in toxicological studies with DDT-type insecticides. The Taft σ* parameter for the electronegative character of substituents correlated well with the uptake of the analogs through insect tarsi and with acute oral toxicities to mice. Substituent groups with stronger electron-withdrawing capacities penetrated more slowly through the insect cuticle and were markedly more toxic to mice. A nuclear magnetic resonance method was utilized to obtain estimated σ* values for use in the correlations.
Microbial degradation kinetics of toxic organic chemicals over a wide range of concentrations in natural aquatic systems
Authors: Hwang Huey-Min , Hodson Robert E. , Lewis David L. 
Published: March 2010

Abstract
The degradation kinetics for several toxic organic compounds (p-cresol, phenol, p- chlorophenol, acetone and methanol) exposed to natural aquatic microbial assemblages were examined over a wide range of concentrations. Compounds were added in radiolabeled form and incubated at 25°C for periods ranging from several hours to one day. The results revealed that degradation kinetics were multiphasic for each of the compounds during at least one sampling period, i.e., the kinetic parameters Kt and Vmax increased with increasing substrate concentration. The observed multiphasicity suggests the presence within the natural microbial assemblages of multiple uptake/degradative systems, each with distinguishable kinetic parameters and each dominating degradation at a different substrate concentration range. If the kinetic diversity is ignored and rates of degradation are calculated based on the assumption that kinetics follow simple hyperbolic (Michaelis-Menten) relationships, then errors as large as 40,000-fold can result. Thus, our results suggest that models for predicting the persistence of such compounds in natural waters should consider changes in kinetic constants with substrate concentration.
Assessing interactions of organic compounds during biodegradation of complex waste mixtures by naturally occurring bacterial assemblages
Authors: Hwang Huey-Min , Hudson Robert E. , Lewis David L. 
Published: March 2010

Abstract
Selected organic chemicals were tested to determine the minimum concentrations at which complete inhibition of microbial degradative processes occurred. Complete inhibition did not occur at less than 2 g/L phenol, 10 g/L toluene or n-butanol and 100 g/L acetone, benzene or methanol. Consequently, microbial degradative processes may play a significant role in the abatement of even very high organic pollutant concentrations. Glucose utilization and thymidine uptake rates were tested as indicators of the toxic effects of the organic pollutants. Both methods accurately indicated the concentrations of organic pollutants required to cause cessation of degradative activities and could serve as indicators of degradative inhibition, in lieu of degradation studies, when analytical processes for test organics are expensive or unavailable. Degradation kinetics of the high organic chemical concentrations followed typical multiphasic kinetic patterns, which tended to yield pseudo-first-order degradation rates over a wide range of chemical concentrations, except when chemical concentrations were sufficiently high to elicit metabolic inhibition.
Acute toxicity of sediment from Eagle Harbor, Washington, to the infaunal amphipod Rhepoxynius abronius
Authors: Swartz Richard C. , Kemp Paul F. , Schults Donald W. , Ditsworth George R. , Ozretich Robert J. 
Published: March 2010

Abstract
Creosote-contaminated sediment from one station (EH08) in Eagle Harbor, Washington, is among the most toxic sediment yet tested from U.S. estuaries and coastal waters. The total concentration of 13 polynuclear aromatic hydrocarbons in EH08 sediment was 6,461 mg/kg (dry wt.). The concentrations of phenanthrene and fluoranthene in this sediment were more than two orders of magnitude greater than their acutely lethal concentrations. In dilution experiments with uncontaminated sediment from Yaquina Bay, Oregon, the 4-d LC50 of EH08 sediment to the amphipod Rhepoxynius abronius (Barnard) was 666 mg/kg (wet wt.). Sediment from other stations within 150 m of EH08 was not acutely toxic to Rhepoxynius, indicating the patchiness of sediment contamination and toxicity in Eagle Harbor.
Kinetic and spectroscopic investigations of the covalent binding of benzidine to quinones
Authors: Ononye Aloysius I. , Graveel John G. , Wolt Jeffrey D. 
Published: March 2010

Abstract
Model studies of the covalent binding of benzidine (4,4′‒diaminobiphenyl), a hazardous biphenyl amine, to humic acid have been carried out through kinetic and spectroscopic investigation of the reaction of benzidine with substituted quinones in aqueous solution. Benzidine reacts with quinones through a single‒phase second‒order mechanism involving addition of the amino group of benzidine to the C=O group of the quinone (imine formation) and the C=C bond in the quinone ring (1,4‒nucleophilic addition), respectively. The products do not show reversibility in water. Reactivity decreases with increase in substitution on the quinone rings. The results provide more understanding of the pathway by which aromatic amines could couple with quinonoid groups present in humic acids.
Effects of contaminants on the frequencies of allozymes in populations of the central stoneroller
Authors: Gillespie Robert B. , Guttman Sheldon I. 
Published: March 2010

Abstract
Allele and genotype frequencies for allozymes of phosphoglucomutase (PGM) differed significantly between populations of the central stoneroller (Campostoma anomalum, Rafinesque) collected from sites above and below impact from industrial activities. The frequencies of the PGM‒A allele and PGM‒AA and PGM‒AB genotypes were significantly less in populations of stoneroller minnows collected from impacted sites than in populations upstream of impact. Stonerollers with these sensitive PGM genotypes and stonerollers with genotypes of malate dehydrogenase MDH‒BB were more sensitive to the toxic effects of copper sulfate than other genotypes under laboratory conditions. These results suggest that individuals with certain allozymes may be more sensitive to the toxic effects of environmental contaminants than those with other genotypes. Selection or elimination of individuals with sensitive genotypes by contaminants may result in a narrowing of genetic diversity in populations and thus increase the susceptibility of these populations to further stress. Electrophoretic determination of genetic structure in fishes appears to be sensitive to changes in water quality and may be a useful tool for monitoring the health of aquatic populations.
Differential survivorship of allozyme genotypes in mosquitofish populations exposed to copper or cadmium
Authors: Chagnon Norman L. , Guttman Sheldon I. 
Published: March 2010

Abstract
Laboratory stocks of mosquitofish (Gambusia affinis) were acutely exposed to copper (0.16–0.24 mg/L) or cadmium (6.7–9.5 mg/L) for 48 h using a static renewal system. Allozyme genotypes at three polymorphic loci: phosphoglucomutase‒2 (PGM‒2), glucose phosphate isomerase‒2 (GPI‒2), and isocitrate dehydrogenase‒2 (ICD‒2) were resolved using a modified starch gel (13%) electrophoretic technique. Differential survivorship of allozyme genotypes was analyzed using a Wilcoxon matched pair signed‒rank test. Copper significantly (p &lt; 0.05) decreased the overall survivorship of fish heterozygous at the GPI‒2 locus. The frequency of the (ab) genotype was significantly higher in the dead fraction of the test populations than in the surviving fraction. The frequencies of the (aa) genotype and the (a) allele at the ICD‒2 locus were significantly higher in female fish surviving exposure to copper than in nonsurviving females. The frequencies of the (bb) genotype and the (b) allele at the GPI‒2 locus were significantly higher in fish surviving exposure to cadmium than in nonsurvivors. These results indicate that some electrophoretically detectable allozymes are more sensitive than others to the toxic effects of environmental pollutants. This suggests that the genetic structure of natural populations should be considered for use as a biological monitor of environmental pollution.
Groundwater ubiquity score: A simple method for assessing pesticide leachability
Authors: Gustafson D. I. 
Published: March 2010

Abstract
Government agencies at both the state and federal levels now face increasing pressures to assess the likelihood of pesticide occurrence in well‒water supplies. Screening methodologies are required in order to determine which pesticides now in use should receive the greatest attention with respect to groundwater, and in order to determine whether elaborate and expensive groundwater testing should be required in order to register a new pesticide. Several screening techniques have been proposed recently, some based on threshold values for critical physical properties of the pesticide, and others based on mathematical models of the leaching process. A different approach is taken in this paper, whereby an index is derived based entirely on the physical properties of those pesticides that have been found either leachable or essentially immobile. The index is based on graphical examination of a plot formed by two widely available pesticide properties: half‒life in soil (tsoil1/2) and partition coefficient between soil organic carbon and water (Koc). Other physical properties, such as water solubility, octanol/water partition coefficient, and volatility from soil, have often been invoked as indicators of leachability, but they are found in this paper to have no useful power in discriminating between “leachers” and “nonleachers.” Scores assigned with the new screening index agree with the results of several recent well‒water monitoring programs, even though point‒source events are thought to be responsible for some of the observed contamination. A nomogram is given that reduces the task of calculating the index to simply placing a straight edge on a diagram.
Toxicity of pyrethroids to marine invertebrates and fish: A literature review and test results with sediment-sorbed chemicals
Authors: Clark James R. , Goodman Larry R. , Borthwick Patrick W. , Patrick James M. , Cripe Geraldine M. , Moody Paul M. , Moore James C. , Lores Emile M. 
Published: March 2010

Abstract
Data on the acute and chronic toxicities of permethrin, fenvalerate, cypermethrin and flucythrinate to marine invertebrates and fish are reviewed. Generally, crustaceans are more sensitive than fish; oysters are comparatively insensitive. The mysid Mysidopsis bahia consistently is among the most sensitive crustaceans tested, with 96—h LC50s of less than 0.02 μg/L for permethrin and of less than 0.01 μg/L for fenvalerate, cypermethrin and flucythrinate. The potential for chronic toxicity to fish is minimal for permethrin, moderate for fenvalerate and relatively great for flucythrinate.
Laboratory toxicity tests were conducted with sediment—source fenvalerate and cypermethrin under static and flow—through conditions to determine the degree of contamination necessary to achieve acute lethal effects on mysids, grass shrimp (Palaemonetes pugio) and pink shrimp (Penaeus duorarum). Mortality was observed in test animals only in systems where the concentrations of sediment—source pyrethroids were sufficient to establish lethal concentrations in the overlying water through sediment/water partitioning. For fenvalerate, lethal effects occurred at nominal sediment concentrations of 0.1 mg/kg (static and flow—through) for mysids and grass shrimp and at 10 mg/kg for pink shrimp. Nominal sediment concentrations of cypermethrin of 0.1 mg/kg (static) or 1.0 mg/kg (flow—through) resulted in mortality in mysids and grass shrimp, whereas 1.0 mg/kg was the only test concentration that caused mortality in pink shrimp in the static and flow—through test systems. The correspondence between aqueous concentrations and LC50s for test animals demonstrated the importance of quantitating the bioavailable portion of pyrethroids in field samples to characterize accurately the environmental risk associated with pyrethroid runoff after agricultural applications.
A comparison and evaluation of field and laboratory toxicity tests with fenvalerate on an estuarine crustacean
Authors: Baughman Douglas S. , Moore David W. , Scott Geoffrey I. 
Published: March 2010

Abstract
Field and laboratory toxicity tests were conducted on the grass shrimp, Palaemonetes pugio, to evaluate the usefulness of laboratory testing in estimating mortality from fenvalerate exposure associated with agricultural runoff. The study examined an integrated approach for assessing the impacts of fenvalerate on estuarine fauna, using 96—h static—renewal and 6—h pulsed—dose laboratory toxicity tests and in situ toxicity tests. The laboratory toxicity tests with fenvalerate gave 96—h LC50 values ranging from 0.007 to 0.071 μg/L and 6—h PDLC50 values ranging from 0.100 to 0.130 μg/L. Comparisons of the results of two field toxicity tests with laboratory—derived LC50 values showed good agreement between field and laboratory toxicity data. The variation between field and laboratory toxicity tests may have been due to the limitations of the water sampling regime used in characterizing the pesticide exposure during the field toxicity tests. These comparisons suggest that a combination of laboratory and field toxicity testing is required to estimate the actual field mortality from fenvalerate exposure associated with agricultural runoff. Future studies should include composite water sampling and more frequent discrete sampling methods to better characterize field exposure regimes.
Structure—activity relationship studies on the toxicity of benzene derivatives: III. Predictions and extension to new substituents
Authors: Hall Lowell H. , Maynard Ellen L. , Kier Lemont B. 
Published: March 2010

Abstract
The additivity model developed earlier for 65 substituted benzenes has been extended to 105 compounds for the fathead minnow system. Toxicity is predicted for 10 compounds not included in the original data set. Four new substituents have been evaluated and their toxicity contributions have been determined by regression analysis. For the whole data set, the following statistics were obtained for the 12—variable model: r=0.921, s=0.31, F=43. The order of toxicity contributions for all substituents now investigated is as follows: —NO2 ≈ —Cl &gt; —Br &gt; —CHO &gt; —CH3 ≈ —F &gt; —NH2 ≈ —CN &gt; —OH ≈ —OCH3 &gt; —COCH3. Also identified in these analyses is the additional toxicity conferred by the ortho—hydroxybenzaldehyde combination. Such a structural arrangement increases toxicity by 1.45 units over both the meta and para arrangements. For the 11 substituents, relationships have been sought between the toxicity contribution and physicochemical parameters, including partition coefficient (π) and electronic parameters, but no significant relation has been found. Also evaluated were five additional substituents for which there are few data. Approximate toxicity contributions are reported for these substituents.
Toxicity of nine benchmark chemicals to Skeletonema Costatum, a marine diatom
Authors: Cowgill U. M. , Milazzo D. P. , Landenberger B. D. 
Published: March 2010

Abstract
The purpose of this study was to determine the sensitivity of a marine diatom to eigm common chemicals and one herbicide. The 50% reduction in the number of cells per milliliter and that of total cell volume × 104 μm3/ml was estimated in relation to each of the nine chemicals. Nominal concentrations of triclopyr triethylamine salt (Garlon 3A), K2Cr2O7, 4—chlorophenol and phenol were slightly toxic (&gt;10 mg/L) according to the U.S. Environmental Protection Agency classificatory scheme, while diethanolamine, chlorobenzene, chloroform, acetone and ethanol were classified as practically nontoxic (&gt;100 mg/L). No observed effect levels were found for each of the two cell measurements in relation to each of the chemicals tested for the 5—d period of the test. The range was found to be from 1 to 6,000 mg/L for total cell count and from 0.65 to 6,000 mg/L for total cell volume. Data on the sensitivities of other organisms to the group of common chemicals are also included. The marine diatom proved to be less sensitive to K2Cr2O7 and diethanolamine than the green alga Selenastrum capricornutum.
Analysis of trifluralin, methyl paraoxon, methyl parathion, fenvalerate and 2,4-D dimethylamine in pond water using solid-phase extraction
Authors: Swineford Douglas M. , Belisle Andre A. 
Published: March 2010

Abstract
A method was developed for the simultaneous extraction of trifluralin, methyl paraoxon, methyl parathion, fenvalerate, and 2,4-D dimethylamine salt in pond water using a solid-phase C18 column. After elution from the C18 column, the eluate was analyzed on a capillary gas Chromatograph equipped with an electron-capture or flame photometric detector.
Isolation of toxins from natural blue-green algae and unicellular cultured Microcystis aeruginosa
Authors: Jinno Hideto , Ando Masanori , Matsui Sachiko , Takeda Mitsuharu 
Published: March 2010

Abstract
The differences between toxins derived from natural populations and cultures of Microcystis aeruginosa and Microcystis viridis, and the toxins of harvested extracts from four strains of Microcystis were investigated using DEAE-cellulose chromatography. Toxins extracted from algal populations consisting of 75% (total Microcystis cells/ml) M. aeruginosa from Lake Kasumigaura, Japan, contained an F-II fraction determined by ion-exchange chromatography; toxins extracted from algal populations consisting of 70% M. viridis from Lake Suwa, Japan, also contained this fraction. Using an improved gradient procedure with ion-exchange chromatography to analyze crude extracts of unicellular cultures of M. aeruginosa strain PS-434, five extracted fractions — F-II, F-IV, F-V, F-VI and F-VII — were determined to contain toxic substances. These fractions were identified as toxic (intraperitoneal injection) in mouse toxicity studies. No toxic fractions were identified in cultures of M. aeruginosa strain NIES-44. Mice LD50s for the crude extracts of cultures of strain PS-434 and the extracts from Lakes Kasumigaura and Suwa were calculated as less than 89.5, 260 and 570 mg/kg, respectively. In natural populations of M. aeruginosa or M. viridis, four toxic fractions (F-IV, F-V, F-VI and F-VII) were not found.
Comparative acute toxicity of diethyleneglycol dinitrate to freshwater aquatic organisms
Authors: Fisher Daniel J. , Burton Dennis T. , Paulson Robert L. 
Published: March 2010

Abstract
The acute toxicity of diethyleneglycol dinitrate (DEGDN) to nine freshwater aquatic organisms was determined. Juvenile fathead minnow, bluegill, channel catfish and rainbow trout were exposed to the compound for 96 h. The invertebrates tested for 48 h included the neonate water flea, early-young amphipod, midge larva and the mayfly larva. The effect of DEGDN on the growth of the green alga Selenastrum capricornutum was also studied.
The toxicity of DEGDN was relatively low to the nine freshwater species tested. Toxicity values ranged from a 5-d EC50 (standing crop) of less than 58.4 mg/L for the alga to a 96-h LC50 of 491.4 mg/L for the fathead minnow. The most sensitive invertebrate, the daphnid, was more sensitive than the most sensitive fish, the bluegill.
Toxicity of 2-sec-butyl-4,6-dinitrophenol (dinoseb) and monosodium methanearsonate (msma), individually and in a mixture, to channel catfish (Ictalurus punctatus) and fathead minnows (pimephales promelas)
Authors: Skelley John Royal 
Published: March 2010

Abstract
The toxicity of technical-grade dinoseb, technical monosodium methanearsonate (MSMA), several formulations of each and a mixture of the two were tested using channel catfish (Ictalurus punctatus Rafinesque) and fathead minnows (Pimephales promelas Rafinesque) under standard conditions at 12°C in soft, reconstituted water. The 96-h LC50s for technical dinoseb were 0.058 mg/L for channel catfish and 0.088 mg/L for fathead minnows. Differences among Vertac General®, Vertac Selective®, Premerge 3®, Gebutox® and technical dinoseb did not affect dinoseb toxicity to either fish species. The 96-h LC50s for technical MSMA were 2,390 mg/L for channel catfish and 1,210 mg/L for fathead minnows. Formulation had a measurable effect on MSMA toxicity, with the Daconate® and Daconate 6® formulations nearly an order of magnitude more toxic than technical MSMA and Bueno 6® to both fish species. The mixture or joint toxicity of technical dinoseb and technical MSMA was greater than additive (synergistic), with additive toxicity indices for channel catfish and fathead minnows of 0.51 and 5.78, respectively.
Chronic effects of contaminated sediments on the urchin Lytechinus pictus
Authors: Thompson Bruce E. , Bay Steven M. , Anderson Jack W. , Laughlin Jimmy D. , Greenstein Darrin J. , Tsukada David T. 
Published: March 2010

Abstract
The urchin, Lytechinus pictus, one of the most abundant species on the mainland shelf off southern California, was exposed to three of the most contaminated sediment types in the region and a control (reference) sediment. Mortality, growth, gonad production and bioaccumulation were measured in the laboratory for 60 d in flow-through experiments. Significant mortality (49%) occurred in Santa Monica Bay sludge outfall sediment. Growth rates were significantly reduced in sediments from Los Angeles Harbor, Palos Verdes sewage outfall and Santa Monica Bay sludge outfall. Both male and female gonad production was significantly decreased in the Santa Monica Bay sludge and Palos Verdes outfall sediments. Gonads accumulated up to 12.6 ppm DDTs and 7.4 ppm polychlorinated biphenyls but decreased in concentrations of Zn, Cu and Cd. The biological effects measured could have been caused by several types of contaminants and were significantly correlated with many of the contaminants measured in the sediments.