bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field evaluation of the EPA (kenaga) nomogram, a method for estimating wildlife exposure to pesticide residues on plants
Authors: Pfleeger Thomas G. , Hayes Robert , Ratsch Hilman , Wickliff Carlos , Fong Anne 
Published: March 2010

Abstract
The Kenaga nomogram was developed by the U.S. Environmental Protection Agency (EPA) in the mid 1970 s and has since been used prior to the registration of a pesticide to estimate the maximum potential pesticide residue level on plant material in the food chain of wildlife. The objective of this study was to evaluate the nomogram using field data. Six pesticides representing a variety of pesticide classes were applied to 15 plant species. Five of the six nomogram categories were tested with plant parts representing differences in surface morphology (i.e., glabrous vs. pubescent leaves). The sixth category was a mixed-grass community seeded with three grass species. Pesticide residue levels were determined the day of application and up to 32 d afterward. While the linear nomogram model does not represent the data as well as other models, relatively few data points (10%) collected on the day of pesticide application exceeded the nomogram predictions. The one systemic pesticide tested had degradation rates similar to nonsystemic pesticides in most categories. Present nomogram categories were significantly different from each other in most cases. However, the forage category should be combined with the leaves and leafy-crop category and have higher estimated residue levels than the Kenaga nomogram. A considerable amount of variation occurs in the level of pesticide residue on plant materials even under controlled experimental conditions and therefore nomogram values should be used as an estimate only until actual field residue data are available. The nomogram, with modifications, appears to be a reasonable regulatory device if careful thought is given in selecting the plant category for making residue estimates.
Modulation of cupric ion activity by pH and fulvic acid as determinants of toxicity in Xenopus laevis embryos and larvae
Authors: Buchwalter David B. , Linder Greg , Curtis Lawrence R. 
Published: March 2010

Abstract
An ion-specific electrode measured cupric ion activity modulated by fulvic acid (FA) and pH in a series of modified Frog Embryo Teratogenesis Assay—Xenopus (FETAX) toxicity assays. Hydrogen ion concentration was the primary determinant of cupric ion activity, while FA played a smaller but significant role. Fulvic acid was a weak copper complexing agent at pH 5.50. At pH 5.50 there was slight reduction of ionic activity and a subsequent attenuation of copper toxicity with 5.0 mg/L FA. At pH 7.50, FA also had a mild attenuating effect on copper toxicity. At pH 6.50, copper was strongly complexed by FA at total copper (TCu) concentrations below its pH-dependent solubility limit. At TCu concentrations above the solubility limit FA enhanced toxicity. There was more cupric ion activity measured in the presence of 0.5 and 5.0 mg/L FA than without it at TCu concentrations above the solubility limit. The proposed mechanism for this behavior was FA action as a nucleation inhibitor. Under the chemical conditions of the pH 6.50 experiments, a stable supersaturation of copper was formed, resulting in a more toxic aqueous matrix.
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

AbstractInduction 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 (&lt;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

Abstract
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

Abstract
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

Abstract
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 (&lt;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 &gt;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

Abstract
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

Abstract
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 &lt;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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

AbstractDespite 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.