bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative structure-activity relationships for predicting mutagenicity and carcinogenicity
Authors: Patlewicz Grace , Rodford Rosemary , Walker John D. 
Published: November 2004

Abstract
Quantitative structure-activity relationships (QSARs) for predicting mutagenicity and carcinogenicity were reviewed. The QSARs for predicting mutagenicity and carcinogenicity have been mostly limited to specific classes of chemicals (e.g., aromatic amines and heteroaromatic nitro chemicals). The motivation to develop QSARs for predicting mutagenicity and carcinogenicity to screen inventories of chemicals has produced four major commercially available computerized systems that are able to predict these endpoints: Deductive estimation of risk from existing knowledge (DEREK) toxicity prediction by komputer assisted technology (TOPKAT), computer automated structure evaluation (CASE), and multiple computer automated structure evaluation (Multicase). A brief overview of these and some other expert systems for predicting mutagenicity and carcinogenicity is provided. The other expert systems for predicting mutagenicity and carcinogenicity include automatic data analysis using pattern recognition techniques (ADAPT), QSAR Expert System (QSAR-ES), OncoLogic computer optimized molecular parametric analysis of chemical toxicity system (COMPACT), and common reactivity pattern (COREPA).
Guidelines for developing and using quantitative structure-activity relationships
Authors: Walker John D. , Jaworska Joanna , Comber Mike H. I. , Schultz T. Wayne , Dearden John C. 
Published: November 2004

Abstract
Numerous quantitative structure-activity relationships (QSARs) have been developed to predict properties, fate, and effects of mostly discrete organic chemicals. As the demand for different types of regulatory testing increases and the cost of experimental testing escalates, there is a need to evaluate the use of QSARs and provide some guidance to avoid their misuse, especially as QSARs are being considered for regulatory purposes. This paper provides some guidelines that will promote the proper development and use of QSARs. While this paper uses examples of QSARs to predict toxicity, the proposed guidelines are applicable to QSARs used to predict physical or chemical properties, environmental fate, ecological effects and health effects.
Mutagenicity of nitroaromatic degradation compounds
Authors: Padda Ranjit S. , Wang Chuanyue , Hughes Joseph B. , Kutty Razia , Bennett George N. 
Published: November 2004

Abstract
The mutagenicity of 2,4-dinitrotoluene (24DNT), and 2,6-dinitrotoluene (26DNT), and their related transformation products such as hydroxylamine and amine derivatives, which are formed by Clostridium acetobutylicum, were tested in crude cell extracts using Salmonella typhimurium TA100. A previous publication already reported the mutagenic activities of 2,4,6-trinitrotoluene (TNT) and its related hydroxylamine derivatives in this test system. A time course of the mutagenicity during the anaerobic transformation of TNT, 24DNT, and 26DNT was also investigated under the same conditions to compare with the results from the pure compounds. The monohydroxylamino intermediates 2-hydroxylamino-4-nitrotoluene (2HA4NT), 4-hydroxylamino-2-nitrotoluene (4HA2NT) and 2-hydroxylamino-6-nitrotoluene (2HA6NT) formed during anaerobic transformation of dinitrotoluenes were proven to be mutagenic in the Ames test using Salmonella typhimurium TA100. This study reports that 4HA2NT is the most stable derivative, whereas 2HA4NT and 2HA6NT are less stable and these intermediates are mutagenic in the Ames test. Both 24DNT and 26DNT and their final metabolites 2,4-diaminotoluene (24DAT) and 2,6-aminotoluene (26DAT) appeared nonmutagenic. In a time-course study of TNT degradation, the temporal sample containing 85% of 2,4-dihydroxylamino-6-nitrotoluene (24HA6NT) is most mutagenic. These observations suggest that the bioremediation approach for treatment of 24DNT and 26DNT should be carried past the hydroxylamino intermediate.
Effects of 4-nonylphenol on reproduction of japanese medaka, Oryzias latipes
Authors: Kang Ik Joon , Yokota Hirofumi , Oshima Yuji , Tsuruda Yukinari , Hano Takeshi , Maeda Masanobu , Imada Nobuyoshi , Tadokoro Hiroshi , Honjo Tsuneo 
Published: November 2004

Abstract
We exposed mature Japanese medaka (Oryzias latipes) to 4-nonylphenol (4-NP) to elucidate its reproductive effects and estrogenic responses. For each treatment, eight breeding pairs were exposed for 3 weeks at measured 4-NP concentrations of 24.8, 50.9, 101, and 184 μg/L. Egg production of the pairs during the third week of exposure (15–21 d) was significantly decreased in the ≥101-μg/L treatment group, and fertility was significantly decreased in the 184-μg/L group. Induction of testis–ova was observed in male fish at all 4-NP concentrations, whereas abnormality of spermatogenesis was found only in those receiving the 184-μg/L treatment. The gonadosomatic index of the males in the 184-μg/L group was also remarkably reduced. Hepatic vitellogenin (VTG) levels were significantly increased in both sexes receiving 4-NP treatments of ≥50.9 μg/L. Overall, the lowest-observed effective concentrations (LOECs) of 4-NP for decreasing reproductive capacity (fecundity and fertility) and eliciting estrogenic responses (induction of testis–ova and VTG) were 101 and ≤24.8 μg/L, respectively. The LOEC for reduced reproduction in medaka was at least four-fold greater than that required to elicit estrogenic responses in male fish. Thus, we suggest that the estrogenic responses expressed in male fish are not responsible for the reduction in reproductive capacity.
Chemical and biomonitoring to assess potential acute effects of Vision® herbicide on native amphibian larvae in forest wetlands
Authors: Thompson Dean G. , Wojtaszek Barbara F. , Staznik Bozena , Chartrand Derek T. , Stephenson Gerald R. 
Published: November 2004

Abstract
In conjunction with operational forest herbicide spray programs in Ontario, Canada, chemical and biological monitoring studies were conducted in 51 different wetlands to quantify the probability and magnitude of contamination by a glyphosate herbicide formulation (Vision®). Wetlands were classified as oversprayed, adjacent, or buffered in relation to the operational target spray blocks. Results show that vegetated buffers significantly mitigated against exposure and thus potential for acute effects. Aqueous concentrations of glyphosate in buffered wetlands were below analytical limits of quantitation (0.02 mg acid equivalent [a.e.]/L) in 14 of 16 cases, with mean concentration (0.03 ± 0.02 mg a.e./L) significantly (p &lt; 0.05) less than that of either adjacent (0.18 ± 0.06 mg a.e./L) or oversprayed wetlands (0.33 ± 0.11 mg a.e./L). Biomonitoring with caged amphibian larvae showed no significant differences among mean mortality (48 h) of either Rana pipiens (p = 0.194) or Rana clamitans larvae (p = 0.129) exposed in situ to Vision under these various wetland conditions. Percent mortality was not significantly (p = 0.05) correlated with exposure concentrations for either amphibian species tested. Results suggest that exposures typically occurring in forest wetlands are insufficient to induce significant acute mortality in native amphibian larvae.
Phospholipase A2 activity in three species of littoral freshwater rotifers exposed to several toxicants
Authors: Pérez-Legaspi Ignacio Alejandro , Rico-Martínez Roberto 
Published: November 2004

Abstract
We analyzed three species of Lecane, a littoral rotifer, for susceptibility to six metals and four organic toxicants using a fluorometric assay based on inhibition of activity of the enzyme phospholipase A2. The metallic toxicants that we tested included Cd, Cr, Cu, Pb, Hg (as HgCl2), and Ti; the organic toxicants included benzene, ethyl acetate, toluene, and vinyl acetate. The three species differed greatly with respect to their susceptibility to the various toxicants. Lecane quadridentata, for example, was particularly sensitive to the four organic compounds (median effective concentration values [EC50] ranged from 6.6 × 10−4–0.987 mg/L). Lecane luna, in contrast, seemed particularly sensitive to metals (EC50 values ranged from 2 × 10−6–1.92 mg/L). Lecane hamata was relatively insensitive to organic solvents (EC50 values ranged from 4.25–126.5 mg/L).
A basin-specific aquatic food web biomagnification model for estimation of mercury target levels
Authors: Hope Bruce 
Published: November 2004

Abstract
In the Willamette River Basin (WRB, Oregon, USA), health advisories currently limit consumption of fish that have accumulated methylmercury (MeHg) to levels posing a potential health risk for humans. Under the Clean Water Act, these advisories create the requirement for a total maximum daily load (TMDL) for mercury in the WRB. A TMDL is a calculation of the maximum amount of a pollutant that a body of water can receive and still meet water-quality standards. Because MeHg is known to biomagnify in aquatic food webs, a basin-specific biomagnification factor can be used, given a protective fish tissue criterion, to estimate total mercury concentrations in surface waters required to lower advisory mercury concentrations currently in fish in the WRB. This paper presents an aquatic food web biomagnification model that simulates inorganic mercury (Hg(II)) and MeHg accumulation in fish tissue and estimates WRB-specific biomagnification factors for resident fish species of concern to stakeholders. Probabilistic (two-dimensional Monte Carlo) techniques propagate parameter variability and uncertainty throughout the model, providing decision makers with credible range information and increased flexibility in establishing a specific mercury target level. The model predicts the probability of tissue mercury concentrations in eight fish species within the range of concentrations measured in these species over 20 years of water-quality monitoring. Estimated mean biomagnification factor values range from 1.12 × 106 to 7.66 × 106 and are within the range of U.S. Environmental Protection Agency national values. Several WRB-specific mercury target levels are generated, which vary by their probability of affording human health protection relative to the federal MeHg tissue criterion of 0.30 mg/kg. Establishing a specific numeric target level is, however, a public policy decision, and one that will require further discussions among WRB stakeholders.
Biodegradation of 2-chlorophenol in forest soil: Effect of inoculation with aerobic sewage sludge
Authors: Lallai Antonio , Mura Giampaolo 
Published: November 2004

Abstract
Decontamination of 2-monochlorophenol-containing forest soil was studied in laboratory experiments. We found that in sterile soil, sorption of chlorophenol can occur. Chlorophenol disappearance of approximately 55% was observed in native soil; both soil sorption and degradation by indigenous soil populations caused this disappearance. In native soil, however, the rate of chlorophenol disappearance was enhanced up to slightly more than 90% by inoculation with a sludge taken from the aeration tank of a municipal wastewater treatment plant. In this sludge, the presence of Alcaligenes and Pseudomonas spp. was observed. In other experiments, addition to the soil of a laboratory culture preacclimated to 2-monochlorophenol did not lead to a greater increase in chlorophenol disappearance. In contrast to native soil, inoculation of sterile soil had no effect on disappearance of the chlorophenol. A possible explanation for the lack of cometabolic degradation is that autoclaving of the soil destroys the organic substances within it.
A toxicity identification evaluation approach to studying estrogenic substances in hog manure and agricultural runoff
Authors: Burnison B. Kent , Hartmann Andreas , Lister Andrea , Servos Mark R. , Ternes Thomas , Van Der Kraak Glen 
Published: November 2004

Abstract
Spreading liquid manure on agricultural fields is a routine way of disposing of animal manure and optimizing the use of nutrients for crops. Limited studies suggest that these wastes may contain a variety of endocrine-disrupting compounds (EDCs) that may be released into aquatic environments through runoff. The purpose of this study was to apply a toxicity identification and evaluation approach to isolate and identify estrogenic compounds in hog manure. A recombinant yeast estrogen screen bioassay was used to detect estrogenicity of high-performance liquid chromatography–separated hog manure fractions. Further analytical analyses of the fractions and comparison to authentic standards resulted in the identification of the endogenous estrogens 17β-estradiol (E2) and estrone, and the phytoestrogen metabolite, equol. High levels of equol (6.9–16.6 ppm) were found to be present in manure that was stored for several months. The endocrine-disrupting potential of equol was characterized further by using fish hormone estrogen receptor (ER), sex hormone binding protein (SSBP), and goldfish androgen receptor (AR) radioligand binding assays. Equol was found to be approximately 1,000- and 200-fold less potent that E2 in competing for binding sites of the SSBP and ER, respectively. Equol's potency was 2,200-fold less than testosterone for the AR. Additional studies confirmed the presence of compounds with estrogenic activity in tile drain water after application of hog manure to an agriculture field. In this case, the contribution of equol to the total estrogenicity of the tile drain water was minimal relative to that of natural estrogens. Overall, this study indicates that further work is warranted to assess the impact that EDCs that originate from agricultural runoff may have on the ecology or physiology of exposed biota.
Microbial degradation of chlorobenzene under oxygen-limited conditions leads to accumulation of 3-chlorocatechol
Authors: Vogt Carsten , Simon Dieter , Alfreider Albin , Babel Wolfgang 
Published: November 2004

Abstract
Five bacterial strains (Acidovorax facilis B517, Cellulomonas turbata B529, Pseudomonas veronii B547, Pseudomonas veronii B549, and Paenibacillus polymyxa B550) isolated on chlorobenzene as the sole source of carbon and energy were screened for the accumulation of the putative metabolic intermediate 3-chlorocatechol during growth on chlorobenzene under oxygen-limited conditions in the presence and absence of nitrate (1 mM). 3-Chlorocatechol accumulated in the growth media of all five strains, but accumulation was significantly less in cultures of A. facilis B517 compared to the other four strains. The presence of nitrate did not influence the biological conversion pattern. However, biologically produced nitrite reacted with 3-chlorocatechol chemically, a reaction that masked the accumulation of 3-chlorocatechol. For P. veronii B549, a clear relationship between the presence of 3-chlorocatechol in the medium and low oxygen concentrations was demonstrated. The assumption is made that accumulation of 3-chlorocatechol is due to the low enzymatic turnover of the 3-chlorocatechol cleaving enzyme, catechol-1,2-dioxygenase, at low oxygen concentrations.
Synthesis and estrogenic activity of bisphenol A mono- and di-β-D-glucopyranosides, plant metabolites of bisphenol A
Authors: Morohoshi Kaori , Shiraishi Fujio , Oshima Yukiko , Koda Tomoko , Nakajima Nobuyoshi , Edmonds John S. , Morita Masatoshi 
Published: November 2004

Abstract
The syntheses and characterization of bisphenol A mno- and di-β-D-glucopyranosides were undertaken to confirm that these compounds are major plant metabolites of bisphenol A (BPA) and to allow an assessment of their estrogenicity. Synthesis involved the glucosidation of unprotected BPA with glucose penta-acetate with phosphorus oxychloride as catalyst. The estrogenic activity of BPA and its mono- and di-β-D-glucopyranosides were measured with an enzyme-linked immunosorbent assay (ELISA)-based estrogen receptor competitive binding assay and with a yeast two-hybrid assay adapted to a chemiluminescent reporter gene (for β-galactosidase). Both methods showed that the estrogenicity of BPA was eliminated by formation of the diglucoside, but whereas the ELISA-based method indicated that reduced activity remained in the monoglucoside, the yeast two-hybrid method showed the monoglucoside to be inactive. Presumably these results reflect the more complex interactions of test compound and cellular components required to demonstrate estrogenicity in the yeast two-hybrid assay. As these processes parallel those in mammalian cells, the yeast two-hybrid method is likely to be the more realistic assay. The uptake and metabolism of BPA by plants offers the possibility of phytoremediation of contaminated water, but also provides an additional route for the compound to enter the human food chain.
Development and field validation of a predictive copper toxicity model for the green alga Pseudokirchneriella subcapitata
Authors: De Schamphelaere Karel A. C. , Vasconcelos Flavio M. , Heijerick Dagobert G. , Tack Filip M. G. , Delbeke Katrien , Allen Herbert E. , Janssen Colin R. 
Published: November 2004

Abstract
In this sudy, the combined effects of pH, water hardness, and dissolved organic carbon(DO) concentration and type on the chronic (72-h) effect of copper on growth inhibition of the green alga Pseudokirchneriella subcapitata were investigated. Natural dissolved organic matter (DOM) was collected at three sites in Belgium and The Netherlands using reverse osmosis. A full central composite test design was used for one DOM and a subset of the full design for the two other DOMs. For a total number of 35 toxicity tests performed, 72-h effect concentration resulting in 10% growth inhibition (EbC10s) ranged from 14.2 to 175.9 μg Cu/L (factor 12) and 72-h EbC50s from 26.9 to 506.8 μg Cu/L (factor 20). Statistical analysis demonstrated that DOC concentration, DOM type, and pH had a significant effect on copper toxicity; hardness did not affect toxicity at the levels tested. In general, an increase in pH resulted in increased toxicity, whereas an increase of the DOC concentration resulted in decreased copper toxicity. When expressed as dissolved copper, significant differences of toxicity reduction capacity were noted across the three DOM types tested (up to factor 2.5). When expressed as Cu2+ activity, effect levels were only significantly affected by pH; linear relationships were observed between pH and the logarithm of the effect concentrations expressed as free copper ion activity, that is, log(EbC50 Cu2+) and log(EbC10 Cu2+): (1) log(EbC50 Cu2+) = —1.431 pH + 2.050 (r2 = 0.95), and (2) log(EbC10 Cu2+) = —1.140 pH — 0.812 (r2 = 0.91). A copper toxicity model was developed by linking these equations to the WHAM V geochemical speciation model. This model predicted 97% of the EbC50dissolved and EbC10dissolved values within a factor of two of the observed values. Further validation using toxicity test results that were obtained previously with copper-spiked European surface waters demonstrated that for 81% of tested waters, effect concentrations were predicted within a factor of two of the observed. The developed model is considered to be an important step forward in accounting for copper bioavailability in natural systems.
A freshwater food web model for the combined effects of nutrients and insecticide stress and subsequent recovery
Authors: Traas Theo P. , Janse Jan H. , van den Brink Paul J. , Brock Theo C.M. , Aldenberg Tom 
Published: November 2004

Abstract
A microcosm experiment that addressed the interaction between eutrophication processes and contaminants was analyzed using a food web model. Both direct and indirect effects of nutrient additions and a single insecticide application (chlorpyrifos) on biomass dynamics and recovery of functional groups were modeled. Direct toxicant effects on sensitive arthropods could be predicted reasonably well using concentration-response relationships from the laboratory with representative species. Model predictions showed that nutrient additions alone caused only small effects on toxicant fate and effects probably due to the relatively high dissipation rate of chlorpyrifos. Enhancement of eutrophication effects by the insecticide was relatively small and seemed to be additive. The recovery of some affected functional groups was hampered in the indoor microcosms due to their isolation from outdoor seed populations. Introducing recolonization scenarios in the model simulated dose-dependent recovery. Recolonization increased the recovering rate after exposure to the pesticide. Modeling can extend the use of microcosms as a link between laboratory and field as this allows the prediction of effects and recovery of ecosystems for concentrations that have not been experimentally tested.
Modeling the influence of temporal and spatial factors on the assessment of impacts of pesticides on skylarks
Authors: Topping Christopher John , Odderskær Peter 
Published: November 2004

Abstract
Spatio-temporal factors strongly influence the population dynamics of animals; thus there have been calls to integrate these factors in environmental impact assessment of toxic compounds. To date, methodological difficulties have probably prevented this union. However, new modeling techniques that could help are available. This paper presents the construction and application of an agent-based simulation model of skylarks in agricultural landscapes and its use to assess the impact of pesticides relative to changes in landscape structure and mortality assumptions. Simulations indicated that pesticides had a negative impact on skylark population size. The annual reduction in numbers was variable and depended primarily upon migration mortality and an interaction between weather and pesticides. Altering landscape structure, crop diversity, or migration mortality assumptions resulted in a population change of approximately 37%, compared to a mean of 4% for pesticides. It was concluded that factors other than pesticides are likely to be limiting skylark numbers in most landscapes. This study demonstrates the importance of modeling the interactions between spatio-temporal environmental factors and the study organisms. Agent-based models (ABMs) are able to extract these relationships as emergent properties of their mechanistic nature. Therefore, we recommend the use of ABM models in future regulatory assessment of pesticides.
Quantitative cationic-activity relationships for predicting toxicity of metals
Authors: Walker John D. , Enache Monica , Dearden John C. 
Published: November 2004

Abstract
Developing and validating quantitative cationic-activity relationships or (Q)CARs to predict the toxicity metals is challenging because of issues associated with metal speciation, complexation and interactions within biological systems and the media used to study these interactions. However, a number of simplifying assumptions can be used to develop and validate (Q)CARs to predict the toxicity of metals: The ionic form is the most active form of a metal; the bioactivity of a dissolved metal is correlated with its free ion concentration or activity; most metals exist in biological systems as cations, and differences in metal toxicity result from differences in metal ion binding to biological molecules (ligand-binding). In summary, it appears that certain useful correlations can be made between several physical and chemical properties of ions (mostly cations) and toxicity of metals. This review provides a historical perspective of studies that have reported correlations between physical and chemical properties of cations and toxicity to mammalian and nonmammalian species using in vitro and in vivo assays. To prepare this review, approximately 100 contributions dating from 1839 to 2003 were evaluated and the relationships between about 20 physical and chemical properties of cations and their potential to produce toxic effects were examined.