bluuebunny/crossref_metadata_2025_split huggingface dataset:
Subchronic mercury exposure in coturnix and a method of hazard evaluation
Authors: Hill Elwood F. , Soares Joseph H. 
Published: March 2010

Abstract
The sublethal toxicity of inorganic (HgCl2) and organic (CH3HgCl) mercury chloride was studied in coturnix (Coturnix japonica) by feeding them mercuric compounds (CH3HgCl at concentrations of 0.125,0.5,2 and 8 ppm; HgCl2 at 0.5, 2, 8 and 32 ppm) in ad libitum diets from hatching to adulthood. Differences of response to the mercurials were compared on the basis of selected indicator enzymes and plasma chemistries. Comparisons of response to equivalent concentrations of the two mercurials and dose-response relationships were made at 1,3,5,7 and 9 weeks. Changes of activity were detected for brain acetylcholinesterase (AChE) and the plasma enzymes aspartate aminotransferase (ASAT), butyrylcholinesterase (BChE), lactate dehydrogenase (LDH) and ornithine carbamoyl transferase (OCT). Changes of ASAT, LDH and OCT were then quantified by probit analysis and the mercurials were compared through their median effective concentrations (EC50). This quantal procedure was based on the establishment of normal control values for each enzyme and then classifying mercury-treated outliers (more than ± 2 SD) as respondents. The EC50 values at 9 weeks for ASAT, LDH and OCT, respectively, were 9, 3 and 63 ppm for HgCl2, and 5, 1 and 4 ppm for CH3HgCl. These results provided the basis for two hazard indices that were calculated by dividing the EC50 into the oral LD50 and the 5-d dietary LC50. Mercury also had contradictory effects on gonadal maturation in both sexes.
Inhibitory interactions of aromatic organics during microbial degradation
Authors: Meyer Joseph S. , Marcus Michael D. , Bergman Harold L. 
Published: March 2010

Abstract
Phenol, benzene and naphthalene were exposed, both singly and in combination, to oil refinery settling pond inocula. Although all three aromatic organics degraded rapidly when dosed singly, benzene and naphthalene were not metabolized in the presence of phenol. These results illustrate the difficulty of predicting environmental fates of complex chemical mixtures.
Placental and mammary transfer of a polychlorinated biphenyl mixture (aroclor 1254) in the European Ferret (Mustela putorius furo)
Authors: Bleavins Michael R. , Breslin William J. , Aulerich Richard J. , Ringer Robert K. 
Published: March 2010

Abstract
Adult female ferrets were found to absorb 85.4% of a single dietary dose of the polychlorinated biphenyl (PCB) mixture Aroclor 1254. Excretion in the days immediately following dosing yielded the greatest quantity of PCBs eliminated in a given time period. In general, urinary excretion represented one-tenth or less of the PCBs excreted via the feces. Placental transfer to the ferret kits was 0.01% (per kit) of the female's absorbed dose when exposure occurred during the first trimester of pregnancy and 0.04% (per kit) when the PCBs were administered during the third trimester. Transplacental exposure to PCBs was considerably less than that reaching the kits through the dam's milk. The ratio of placental to mammary transfer, following 1 week of lactation, was calculated to be approximately 1:15 for the offspring of first-trimester-dosed females and 1:7 for the offspring produced by females treated during the third trimester.
Estimation of bioconcentration in marine species using structure-activity models
Authors: Zaroogian G. E. , Johnson M. , Heltshe J. F. 
Published: March 2010

Abstract
Structure-activity models, which were developed to predict bioconcentration of organic chemicals in freshwater fish, were tested for use with several marine species (Cyprinodon variegatus, Lagodon rhomboides, Crassostrea virginica, Mytilus edulis). Significant linear relationships existed between the bioconcentration factor (BCF) for each marine species tested and the log of the octanol/water partition coefficient (P). The results suggest that freshwater models can be used to predict the BCF of a chemical in marine species, since the slopes of the freshwater models were within the 95% confidence intervals for marine models. Models derived from data on freshwater species were used to calculate BCF values for each of the marine species. The calculated BCF values were compared with the measured BCF values for each marine species and those measured for the fathead minnow (Pimephales promelas). The data indicate that the log BCF can be estimated for the marine species using freshwater models to within one order of magnitude for a minimum of 71% of the chemicals having a range of 3,000,000 in the partition coefficient (1.61 to 6.50 in log P). It appears that models based on data from freshwater species offer the same precision in estimation of BCF values for marine species as for freshwater fish. Good agreement existed between measured and calculated BCF values for both L. rhomboides and M. edulis, whereas the data for C. virginica were more variable and those for C. variegatus were the most variable. Tests indicated that, generally, calculated BCF values overestimate the measured BCF values. Significant linear relationships existed between measured BCF values for P. promelas and each marine species, except M. edulis.
Comparative toxicity of copper and acridine to fish, Daphnia and algae
Authors: Blaylock B. G. , Frank M. L. , McCarthy J. F. 
Published: March 2010

Abstract
A comparison was made of the sensitivity of fish, Daphnia and algae to the toxic effects of copper and acridine. A series of toxicity tests was conducted with these organisms, and the following biological endpoints determined: LC50s for fish, LC50s and effects on reproduction of Daphnia and 50% inhibition of the growth rate of algae. The 96-h LC50s for bluegill (Lepomis macrochirus) and Daphnia magna exposed to copper were 2.2 and 0.13 mg/L, respectively. A chronic exposure to 0.03 mg/L of copper for 14 d significantly decreased reproduction in Daphnia. Exposure to 0.4 and 0.2 mg/L copper inhibited the growth rate of Selenastrum capricornutum and Chlorella vulgaris, respectively, by 50%. The 96-h LC50s for fathead minnows (Pimephales promelas) and D. magna exposed to acridine were 2.3 and 3.1 mg/L, respectively. A chronic exposure to 1.25 mg/L acridine for 14 d significantly inhibited reproduction in Daphnia, and an exposure to 0.9 mg/L inhibited the growth rate of S. capricornutum by 50%. Based on the biological endpoints determined in these tests, Daphnia were more sensitive to copper than were fish or algae. In contrast, the most sensitive biological endpoint in tests with acridine was the inhibition of algal growth. Comparison of these test results indicates that short-term toxicity tests used for screening toxicants for possible environmental effects should include both plant and animal species.
The use of quantitative structure-activity relationships to predict the acute and chronic toxicities of organic chemicals to fish
Authors: McCarty L. S. , Hodson P. V. , Craig G. R. , Kaiser K. L. E. 
Published: March 2010

Abstract
Quantitative structure-activity relationships (QSARs) predict bioconcentration and acute toxicity to fish of chemicals causing narcosis on the basis of hydrophobicity, as measured by the octanol/water partition coefficient (Kow). Since the development of water quality objectives to protect fish is limited by the availability of suitable chronic toxicity data, we applied the QSAR concept to published and unpublished data to determine (a) whether chronic toxicity could be related to Kow and (b) whether application factors are constant, i.e., whether QSARs for acute and chronic toxicity are parallel. Our conclusions are as follows: (1) A QSAR, based on hydrophobicity (log Kow), appears to exist for the chronic toxicity of organic chemicals inducing acute toxicity by narcosis. Although not definitive, this QSAR was not parallel to that for acute toxicity and does not appear to support the concept of constant application factors. (2) Log Kow has a major effect on the rate of net bioconcentration of certain organic chemicals; therefore, the relationship of toxicity to log Kow may not be linear if exposure times are fixed, as very different amounts of toxicants will be taken up over a fixed time period. (3) As a result of the effect of log Kow on bioconcentration rates, many toxicity tests of relatively short, fixed duration may underestimate toxicity of some hydrophobic organic compounds, especially those exhibiting high log Kow values. Hence, water quality objectives developed directly from this data, without appropriate compensation, may not be restrictive enough. (4) To increase the accuracy, comparability and applicability of aquatic bioassay test results, especially for compounds of widely differing hydrophobicity, standard tests should be redesigned. For example, it may be more accurate if the exposure or dosage for the test organism is expressed as a summation of the periodically calculated product of body toxicant level and time up to predetermined summation values.
Reevaluation of volatile nitrosamines in human feces
Authors: Suzuki Kunio , Mitsuoka Tomotari 
Published: March 2010

Abstract
The artifactual generation of N-nitrosamines during analytical procedures and the presence of volatile nitrosamines in human feces were reinvestigated. Various solvents and desiccants — sodium sulfate, magnesium sulfate and calcium chloride—were highly catalytic in nature and induced marked N-nitrosation of secondary amines. During the N-nitrosamine analysis, high levels of volatile nitrosamines, detected in the original method using dichloromethane as the extracting solvent and sodium sulfate as the desiccant, were artifactually generated. Few volatile nitrosamines were detected by the new method, in which extraction by ether and dehydration by potassium carbonate were carried out. The recovery values of volatile nitrosamines by the new method were similar to the values obtained by the original method. Therefore, it is concluded that volatile nitrosamines do not seem likely to be present in significant amounts in human feces.
Characterizing the aerobic and anaerobic microbial activities in surface and subsurface soils
Authors: Ward Thomas E. 
Published: March 2010

Abstract
Studies were conducted to characterize the aerobic and anaerobic microbial activities in surface and subsurface soils of septic tank tile fields. Under aerobic conditions, the indigenous microflora in the soils degraded the natural substrates and many of the synthetic chemicals tested. Half-lives (t1/2) for the biodegradation (14CO2 production) of glucose and glutamic acid ranged from 2 to 5 h in surface soils and from 8 to 25 h in subsurface soils. Degradation of stearic acid was slower in both surface (t1/2 = 118 h) and subsurface (t1/2 = 82 to 312 h) soils. 14CO2 evolution from the synthetic chemicals methyl parathion and 2,4-D was more variable than that from the natural substrates and occurred in the surface soil but in only one of the two subsurface soils tested. The aerobic biodegradation of nitrilotriacetate (NTA) was studied only in the two subsurface soils from the tile fields. NTA was mineralized in both soils and the half-life for 14CO2 production ranged from 86 to 161 h. When the surface and subsurface soils were incubated under anaerobic (nitrate-reducing) conditions, active denitrification by the indigenous microflora was observed. In surface soils, denitrification occurred immediately after an anaerobic preincubation (12 to 24 h) and the N2O production curve was linear. In subsurface soils, N2O production occurred only after 32 to 44 h of anaerobic incubation and was described by an S-shaped curve. Biodegradation of the natural substrates (glucose, glutamic and acetic acid) under these anaerobic conditions ranged from 1 to 2 h for the surface soil to 2 to 20 h for subsurface soils. The half-life for the anaerobic mineralization of NTA ranged from 49 to 125 h in the subsurface soils. The results indicate that the indigenous microflora in the subsurface have lower activities than do those in surface soils; however, the subsurface microflora can effectively mineralize natural and certain synthetic substrates under aerobic and denitrifying conditions.
A metabolic derivation of DDE from kelthane®
Authors: Risebrough Robert W. , Jarman Walter M. , Springer Alan M. , Walker Wayman , Hunt W. Grainger 
Published: March 2010

Abstract
DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), the DDT derivative that causes thinning of the eggshells of sensitive bird species, is metabolically formed in mallard ducks fed Kelthane®, a widely used acaricide that consists of technical dicofol, a mixture of compounds synthetically derived from technical DDT. Technical dicofol mixtures contain very low levels of p,p'-DDT, which has been assumed to be the only precursor to environmental DDE. Applications of Kelthane and of other products containing technical dicofol would therefore increase the environmental input of DDE, accounting at least in part for recent observations of high levels of DDE in environmental samples from Texas, New Mexico, Arizona and California that contained only trace amounts of DDT. Among the components of Kelthane, chloro-DDT (1,1,1,2-tetrachloro-2,2-bis(p-chlorophenyl)ethane) is converted to DDE under certain laboratory conditions. Levels of chloro-DDT in the Kelthane mixture employed could account for all of the DDE metabolically formed in the ducks. The data leave unresolved the question of whether DDE may be derived from p,p'-dicofol (1,1-bis(p-chlorophenyl)-2,2,2-trichloroethanol), the principal ingredient of technical dicofol, under either experimental or environmental conditions.
Biological half-lives of chlorinated dibenzo-p-dioxins and dibenzofurans in rainbow trout (Salmo gairdneri)
Authors: Niimi A. J. , Oliver B. G. 
Published: March 2010

Abstract
The biological half-lives of five dibenzo-p-dioxins and two dibenzofurans were determined in rainbow trout following a single oral exposure. Estimated half-lives ranged from 2 d for 2,7-dichlorodibenzo-p-dioxin to 43 d for 1,2,3,4-tetrachlorodibenzo-p-dioxin among the dioxins, and from 12 d for octachlorodibenzofuran to 24 d for 3,6-dichlorodibenzofuran. No consistent relationship was shown between half-life and the degree of chlorination. Absorption efficiencies varied from 2 to greater than 30%, although most values ranged from 5 to 16%.
Arthropods associated with pesticide leach lines in selected orchards in central New York
Authors: Baker P. B. , Hoebeke E. R. , Barnard J. , Spittler T. D. 
Published: March 2010

Abstract
Chemical control centers were constructed on selected farms in Wayne County, New York, to minimize pesticide pollutants. These centers provided areas where several classes of agricultural chemicals, primarily those from spray operations, could be handled and disposed of safely. We surveyed the arthropod fauna found above the pesticide leach lines and in adjacent soils. Of the 70 arthropod taxa determined, we identified the following families: Diptera (18 families), Hymemoptera (12), Coleoptera (7), Hemiptera (3), Homoptera (1) and Thysanoptera (1). Seasonal comparisons of arthropods above the pesticide leach lines and in the checks showed no apparent differences. Slight taxa variations were observed within and between farms with chemical control centers. No residues greater than 0.2 ppm were found in either water or soil samples. These results imply that no contamination of the environment was caused by the use of the chemical control centers.
Conditional stability constants and binding capacities for copper (II) by dissolved organic carbon isolated from surface waters of the southeastern United States
Authors: Giesy John P. , Alberts James J. , Evans David W. 
Published: March 2010

Abstract
Dissolved organic carbon (DOC), isolated from each of nine surface waters in the southeastern United States, was fractionated into two nominal molecular size fractions, i.e., 52 Å &lt; fraction I &lt; 4,500 Å and 13 Å &lt; fraction II &lt; 52 Å. The binding capacities and overall conditional stability constants (K̄') for copper were determined by selective ion electrode. The binding capacities ranged from 2.4 × 10−7 to 1.3 × 10−5 M Cu/mg DOC, with a mean for all locations and fractions of 2.2 × 10−6 (SD = 6.2 × 10−5, n = 15). There was no significant difference (Mann-Whitney U Test, p &gt; 0.2) between binding capacities of fractions I and II. Sensitivity analyses showed that the overall mean binding capacity was adequate for use in simulation models. We estimated overall conditional stability constants by seven mathematical techniques, including both discrete and continuous models. The thermodynamic, geochemical simulation model GEOCHEM was used to determine the sensitivity of predictions to variation in both binding capacity and overall conditional stability constants estimated by each technique. Predictions were compared with titrations of isolated humate fractions and whole waters. The two-component Scatchard function, a discrete model, and the Gaussian-Scatchard function, a continuous model, gave the most accurate predictions in these simulations. We endorse the use of the Gaussian-Scatchard function because it is flexible and has a stronger theoretical basis. Stability constants (K') were calculated for measured values of free and bound metal and ligand across a metal-organic ligand titration curve. These values were dependent on the copper/total ligand ratio and varied on a continuum of binding strength by as much as a factor of 100 for a given fraction and location. The means of maximum conditional stability constants calculated across locations were 5.2 × 105 (SD = 3.9 × 105, n = 7) and 5.9 × 104 (SD = 4.05 × 104, n = 7) for fractions I and II, respectively. The median, maximum conditional stability constant for fraction II was significantly weaker (Mann-Whitney U Test, p &lt; 0.005) than that for fraction I. The number of sites with each K' were log10-normally distributed, with proportionately more of the weaker binding sites.
Comparisons of single-species, microcosm and experimental pond responses to atrazine exposure
Authors: Larsen David P. , Stay Frank , Shiroyama Tamotsu , Frank DeNoyelles  
Published: March 2010

Abstract
Results from single-species toxicity tests form the basis for guidance about concentrations of chemicals that are likely to be environmentally hazardous. Microcosm bioassays have been proposed as better tools for this purpose under some circumstances. Rarely have comparisons been made among the responses in the various test systems and those seen in natural communities. We compared the responses among single-species algal assays, a synthetic microcosm (the Taub microcosm) and experimental ponds exposed to similar concentrations of atrazine by comparing concentrations of atrazine that reduced algal activity or biomass to 50% of control values (EC50). Eight algal species were examined; mean species EC50 values for 14C uptake ranged from 37 to 308 μg/L. For the Taub microcosm, EC50 values were 103 to 159 μg/L for 14C uptake, 126 to 165 μg/L for dissolved oxygen production and 106 to 164 μg/L for dissolved oxygen consumption. Values were dependent on the time intervals selected for calculations. In the ponds, EC50 values for 14C uptake were 100 μg/L and for chlorophyll a, 82 μg/L. The basic similarity among EC50 values across test systems suggests that results from a combination of single-species assays, or the Taub microcosm, provided a reasonable estimate of the concentration of atrazine that produced similar direct effects on more natural communities.
Development of environmental scenarios for modeling the fate of agricultural chemicals in soil
Authors: Oliver George R. , Laskowski Dennis A. 
Published: March 2010

Abstract
Modeling has become a popular preliminary screening and predictive tool for assessing the environmental fate of agricultural chemicals. For modeling to be effective, realistic soil and climatic background inputs must be used. A procedure to quickly develop these environmental scenarios from readily available data sources for modeling leaching and dissipation is discussed, using the herbicide tridiphane as an example. Computerized soil survey information was used to identify soils most likely to be encountered in major use areas. A climatic model generated rainfall patterns for the study areas and provided the probability statement for the environmental assessment. Less than 5 man-days of effort were required for the formulation of four realistic scenarios to use in the evaluation of the leaching and dissipation of tridiphane in key future markets.
Cholinesterase inhibition in meadow voles (Microtus Pennsylvanicus) following field applications of orthene®
Authors: Jett David A. 
Published: March 2010

Abstract
Brain acetylcholinesterase activity in field-caught meadow voles (Microtus pennsylvanicus) was depressed after a field-spray of Orthene® (acephate: acetylphosphoramidothioic acid O,S-dimethyl ester) by as much as 32% in 1982 and 38% in 1983. Short-term recovery was demonstrated and occurred in a time-dependent fashion in 1982. Plasma Cholinesterase levels were more variable but also were depressed. Residues were detected in vegetation samples and in the gastrointestinal tracts of exposed voles. Residues in vegetation were diluted or absent 7 to 8 d following the treatment.
Bioconcentration and disposition of 1,3,6,8-tetrachlorodibenzo-p-dioxin and octachlorodibenzo-p-dioxin by rainbow trout and fathead minnows
Authors: Muir D.C.G. , Yarechewski A.L. , Knoll A. , Webster G.R.B. 
Published: March 2010

Abstract
Accumulation of 14C-labeled 1,3,6,8-tetrachlorodibenzo-p-dioxin (TCDD) and octachlorodibenzo-p-dioxin (OCDD) from water by rainbow trout fry (Salmo gairdneri) and fathead minnows (Pimephales promelas) was studied using a 5-d uptake and 24 to 48-d depuration period. Average exposure concentrations ranged from 4 to 211 ng/L for 1,3,6,8-TCDD and from 9 to 415 ng/L for OCDD. Equilibrium bioconcentration factors for total 14C in fish, calculated by use of a two-compartment first-order rate model, were 2,100 and 5,702 for 1,3,6,8-TCDD in trout fry and minnows, respectively, and 85 and 2,226 for OCDD in the same species. Elimination rates of both isomers were rapid, with half-lives of 14C ranging from 6 to 9 d for 1,3,6,8-TCDD and from 5 to 13 d for OCDD. The highest concentrations of radiolabeled 1,3,6,8-TCDD and OCDD were found in bile. A metabolite of 1,3,6,8-TCDD in bile was identified as a conjugate of a hydroxylated tetrachloro-derivative. Dietary exposure of rainbow trout resulted in low accumulation factors, ranging from 0.034 for OCDD to 0.018 for 1,3,6,8-TCDD, based on toluene-extractable radioactivity.
Effect of pulse exposure to methoxychlor on brain serotonin levels in american flagfish (Jordanella Floridae, goode and bean) as modified by time after exposure, concentration and gender
Authors: Holdway D.A. , Sloley B.D. , Downer R.G.H. , Dixon D.G. 
Published: March 2010

Abstract
Adult American flagfish (Jordanella floridae) were exposed for 2 h to 1.6, 1.9, 3.1 or 5.1 mg L−1 of the chlorinated hydrocarbon insecticide methoxychlor. Control and ethanol-carrier control treatments were also maintained. Fish were sampled at 2, 6, 24, 48 and 336 h after exposure, and the concentrations of tryptophan, serotonin and 5-hydroxyindole acetic acid in brain tissue were determined. Flagfish exposed to the three highest concentrations of methoxychlor had significantly lower concentrations of serotonin, relative to controls, 2, 6 and 24 h after exposure. Serotonin concentrations had returned to control levels by 48 h. The period of serotonin depression corresponded with observed convulsive activity in the exposed fish. Female flagfish had significantly higher brain levels of serotonin than did males. Although tryptophan and 5-hydroxyindole acetic acid levels were unaffected by methoxychlor exposure, the levels of both were significantly depressed by the concentration of ethanol carrier (270 mg L−1) used. Serotonin levels were unaffected by ethanol. The brain weight of flagfish was found to be related to body weight by the equation brain weight (mg) = 2.53 + 5.72 body weight (g) (n = 139; r2 = 0.74; p &lt; 0.001).