bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting the relative toxicity of metal ions using ion characteristics: Microtox® bioluminescence assay
Authors: McCloskey John T. , Newman Michael C. , Clark Sue B. 
Published: March 2010

Abstract
Quantitative structure—activity relationships have been used to predict the relative toxicity of organic compounds. Although not as common, ion characteristics have also proven useful for predicting the relative toxicity of metal ions. The purpose of this study was to determine if the relative toxicity of metal ions using the Microtox® bioassay was predictable using ion characteristics. Median effect concentrations (EC50s) were determined for 20 metals in a NaNO3 medium, which reflected freshwater speciation conditions, using the Microtox bacterial assay. The log of EC50 values was modeled using several ion characteristics, and Akaike's Information Criterion was calculated to determine which ion characteristics provided the best fit. Whether modeling total ion (unspeciated) or free ion (speciated) EC50 values, the one variable which best modeled EC50s was the softness index (σp, i.e., [coordinate bond energy of the metal fluoride — coordinate bond energy of the metal iodide]/[coordinate bond energy of the metal fluoride]), while a combination of χ2mr (χm = electronegativity, r = Pauling ionic radius) and |log KOH| (absolute value of the log of the first hydrolysis constant, KOH for Mn+ + H2O → MOHn−1 + H+) was the best two-variable model. Other variables, including ΔE0 and χ2mr (one-variable models) and (ΔN/ΔIP, ΔE0) and (χ2mr, Z2/r) (two-variable models), also gave adequate fits. Modeling with speciated (free ion) versus unspeciated (total ion) EC50 values did not improve fits. Modeling mono-, di-, and trivalent metal ions separately improved the models. We conclude that ion characteristics can be used to predict the relative toxicity of metal ions whether in freshwater (NaNO3 medium) or saltwater (NaCl medium) speciation conditions and that this approach can be applied to metal ions varying widely in both valence and binding tendencies.
Statistical implications of end-point selection and inspection interval in the Daphnia reproduction test—A simulation study
Authors: Ratte Hans Toni 
Published: March 2010

Abstract
A general simulation approach was developed for validating biotest end points in the Daphnia reproduction test. Various toxic-effect scenarios, sample sizes, and inspection regimes were used to study the behavior and robustness of different end points. The intrinsic rate of natural increase (IR) and the capacity for increase (CI) were estimated because of their ecological significance. Both parameters were compared to conventionally chosen end points, the offspring number per female (ON) and the percent mortality (MO). The IR appeared to be the most sensitive end point among the different toxic-effect scenarios. In particular, effects on the age at first reproduction, which are highly relevant in population dynamics, were integrated. In general, the CI was as sensitive as the IR. However, the CI tends to overestimate the first brood. In contrast to ON and MO, both the IR and CI responded sensitively to the inspection regime. The IR was found to require daily recording of reproduction and mortality events, at least until the first broods appeared. Whereas the value of the CI remained questionable, from a statistical and ecological viewpoint the IR appeared to be superior.
Evaluation of metals in marine and freshwater surficial sediments from the environmental monitoring and assessment program relative to proposed sediment quality criteria for metals
Authors: Leonard Edward N. , Ankley Gerald T. , Hoke Robert A. 
Published: March 2010

Abstract
Surficial sediments collected from Lake Michigan (N = 46) and the Virginian Province of the east coast of the U.S. (N = 131) by the Environmental Monitoring and Assessment Program (EMAP) of the U.S. Environmental Protection Agency (EPA) were evaluated relative to a proposed approach to sediment quality criteria (SQC) for five metals (copper, cadmium, zinc, nickel, and lead). Concentrations of acid‒volatile sulfide (AVS), simultaneously extracted metals (SEM) from the AVS extraction, total metals, and total organic carbon were measured in the sediments. Interstitial pore‒water concentrations of the five metals also were measured in the freshwater sediment samples. Overall, 91% of 131 surficial marine sediments and 50% of 46 surficial freshwater sediments contained detectable AVS. In 93 of the marine sediments the concentrations of AVS were greater than total SEM (molar sum of copper, cadmium, zinc, nickel, and lead) indicating a low probability of bioavailable metal. In contrast, 91% of the surficial freshwater samples contained greater concentrations of total SEM than AVS. However, pore‒water concentrations of the five metals in the freshwater samples were uniformly low and never exceeded 0.3 toxic units based on an additive toxicity model that utilized final chronic values from EPA water quality criteria documents for the five metals. These predictions of minimal metal bioavailability in the EMAP samples were consistent with a general lack of toxicity in laboratory assays with the sediments and with the fact that they had been collected predominantly from ostensibly uncontaminated sites.
Parameters affecting the desorption of hydrophobic organic chemicals from suspended sediments
Authors: Borglin Sharon , Wilke Amy , Jepsen Rich , Lick Wilbert 
Published: March 2010

Abstract
Recent work has demonstrated that both the adsorption and desorption of hydrophobic organic chemicals to sediments and soils can be quite slow and that chemical equilibrium may not be a good approximation in many real situations. By means of long‒term batch experiments, this has been recently and clearly shown for the adsorption of hexachlorobenzene and three polychlorinated biphenyls to suspended sediments. In the present study, long‒term desorption experiments are performed with three hydrophobic organic chemicals (hexachlorobenzene and two polychlorinated biphenyls) and suspended sediments. Desorption times are on the order of a month to several years. It is shown that the desorption rates are dependent on the particle/floc size and density distributions, the type of water, the amount of organic carbon in the sediments, the time of adsorption before desorption, and the chemical partition coefficient. It is also shown that a simple chemical diffusion model with an effective diffusion coefficient dependent on the porosity of the particle/floc, the organic content of the sediments, and the chemical partition coefficient, along with proper consideration of particle/floc size and density distributions is sufficient to explain the experimental results.
Heavy metals in laughing gulls: Gender, age and tissue differences
Authors: Gochfeld Michael , Belant Jerrold L. , Shukla Tara , Benson Tom , Burger Joanna 
Published: March 2010

Abstract
We examined concentrations of lead, cadmium, mercury, manganese, selenium, and chromium in feathers, liver, kidney, heart, and muscle of known-aged laughing gulls (Larus atricilla) that hatched in Barnegat Bay, New Jersey and were collected at John F. Kennedy International Airport, New York 1 to 7 years later. Concentrations differed significantly among tissues, and “tissue” entered all the regression models explaining the greatest variation in metal levels. Age of bird contributed significantly to the models for lead, cadmium, selenium, and chromium. Although there were significant gender differences in all body measurements except wing length, there were few differences in metal levels. Males had significantly higher lead levels in feathers, and females had significantly higher selenium levels in heart and muscle tissue. For lead, 3-year olds had the highest levels in the heart, liver, and kidney, and levels were lower thereafter. Mercury levels in feathers and heart decreased significantly with age. Cadmium levels increased significantly with age for feathers, heart, liver, and muscle, although there was a slight decrease in the 7-year olds. Selenium levels decreased significantly with age for all tissues. Chromium levels increased with age for liver and heart.
Effect of the fungicide clotrimazole on the bioconcentration of benzo[a]pyrene in gizzard shad (Dorosoma cepedianum): In vivo and in vitro inhibition of cytochrome P4501A activity
Authors: Levine Steven L , Czosnyka Hillary , Oris James T 
Published: March 2010

Abstract
Clotrimazole was found to inhibit in vivo and in vitro hepatic microsomal ethoxyresorufin O-deethylase (EROD) activity in gizzard shad (Dorosoma cepedianum). Gizzard shad pretreated with 50 mg clotrimazole/kg and then exposed for 1 or 3 d to benzo[a]pyrene (BaP) (0.86 μg/L) had significantly lower EROD activity compared to fish that were exposed to BaP alone. Following 1 and 3 d of BaP exposure, groups pretreated with clotrimazole had a 14- and 4-fold decrease in EROD activity and had biocon-centrated 8 and 11 times more parent BaP, respectively, compared to groups exposed to BaP alone. Addition of clotrimazole to BaP-induced microsomes produced a type II binding spectrum and was an effective in vitro inhibitor of EROD activity. The median inhibitory concentration for EROD activity was 0.51 μM clotrimazole. Kinetic and spectral experiments suggest that the mechanism of inhibition by clotrimazole is noncompetitive. Reduction in the rate of oxidative BaP metabolism is hypothesized to result from noncompetitive inhibition of cytochrome P4501A and other P450 enzymes that metabolize BaP.
Enhanced copper adsorption and morphological alterations of cells of copper-stressed Mucor rouxii
Authors: Gardea-Torresdey Jorge L , Cano-Aguilera Irene , Webb Robert , Gutierrez-Corona Félix 
Published: March 2010

Abstract
Fungi are ubiquitous and can become dominant in metal-polluted habitats. Some fungal strains are tolerant to metal toxicity. The presence of a high copper concentration in the culture medium induced morphological changes in the copper-tolerant strain of Mucor rouxii. Copper binding by strains of M. rouxii cultured at a trace (1.6 × 10−3 mM) copper concentration was less effective than those cultured at a high (3.2 mM) copper concentration. These experiments were performed at an optimum time of 30 min and a pH of 5 for Cu2+ binding. Our results suggest that a passive metal-binding mechanism makes the majority of total copper binding. These preliminary findings suggest that the presence of high levels of copper in the culture medium allow the development of chemical functional groups on the fungal surface, which led to an enhanced copper-binding ability and induced important morphological changes in M. rouxii.
Effects of ion pairing with calcium and magnesium on selenate availability to higher plants
Authors: Parker David R , Tice Kathy R , Thomason David N 
Published: March 2010

Abstract
The effects of solution speciation on the bioavailability of trace metals are well documented, but the role of speciation in the bioavailability of oxyanionic trace elements that may form significant ion pairs with Ca and Mg in saline media has not been investigated. We assessed the effects of such ion pairing on the availability of selenate to representative monocotyledonous and dicotyledonous higher plants. Formation constants for the CaSO 04 and CaSeO 04 ion pairs were experimentally determined using a Ca2+ ion-selective electrode. The published value of 102,3 for CaSO 04 formation was confirmed, but the value of 1027 for CaSeO 04 was found to be in error; a value of 102,0 is proposed here as the correct formation constant. Five solution culture experiments were conducted using alfalfa (Medicago sativa L.) or tall wheatgrass (Elytrigia pontica [Podp.] Holub) with treatments consisting of NaSeO4 levels in combination with various levels of MgCl2 or CaCl2. Both shoot Se concentrations and whole-plant Se contents were highly correlated with the free SeO2−4 activity but were poorly correlated with the sum of the free ion plus Ca and Mg ion pair species. Thus, we have shown, for the first time, that the free ion model of trace metal bioavailability is also valid for oxyanions that form complexes with Ca and Mg in saline media but that this conclusion hinges critically on the accuracy of the pertinent formation constants.
Declining bioavailability and inappropriate estimation of risk of persistent compounds
Authors: Kelsey Jason W , Alexander Martin 
Published: March 2010

Abstract
Earthworms ( Eisenia foetida) assimilated decreasing amounts of atrazine, phenanthrene, and naphthalene that had been incubated for increasing periods of time in sterile soil. The amount of atrazine and phenanthrene removed from soil by mild extractants also decreased with time. The declines in bioavailability of the three compounds to earthworms and of naphthalene to bacteria were not reflected by analysis involving vigorous methods of solvent extraction; similar results for bioavailability of phenanthrene and 4-nitrophenol to bacteria were obtained in a previous study conducted at this laboratory. We suggest that regulations based on vigorous extractions for the analyses of persistent organic pollutants in soil do not appropriately estimate exposure or risk to susceptible populations.
Magnitude and persistence of herbicide residues in farm dugouts and ponds in the Canadian prairies
Authors: Grover Raj , Waite Don T , Cessna Allan J , Nicholaichuk Wally , Irvin Don G , Kerr Lorne A , Best Kelly 
Published: March 2010

Abstract
Farm ponds or dugout waters were monitored for residues of seven major herbicides used in the Canadian prairies from fall of 1987 to spring of 1989. The frequencies of confirmed detection of herbicides in water samples, depending on the time of sampling, in decreasing order were: 2,4-dichlorophenoxyacetic acid (2,4-D; 93–100%), diclofop (46–95%), bromoxynil (50–85%), 4-chloro-2-methyl-phenoxyacetic acid (MCPA; 33–70%), triallate (28–63%), dicamba (17–55%), and trifluralin (0–18%). The corresponding frequencies of quantifiable residues (≥0.05 μg/L) were lower, ranging from 75 to 86% for 2,4-D to 0 to 7% for dicamba. Median residues in all water samples were near or below the quantification limits of 0.05 μg/L. Maximum residues varied widely and were (μg/L): trifluralin (not detectable [ND]–0.11), bromoxynil (0.27–0.33), dicamba (ND–11.2), triallate (0.05–0.87), MCPA (0.12–1.97), 2,4-D (0.64–2.67), and diclofop (0.27–3.47). Maximum residues were seasonal and declined to near or below detection limits by the following sampling time. Median values were two to three orders of magnitude less than the corresponding maximum allowable concentration and interim maximum allowable concentration guidelines for drinking water in Canada and the United States. Maximum values were also less than these guidelines. Only the maximum values for residues of MCPA and 2,4-D approached the guidelines for these herbicides in water used for irrigation.
Precision and sensitivity of a seven-day growth and survival toxicity test using the west coast marine mysid crustaceanHolmesimysis costata
Authors: Hunt John W , Anderson Brian S , Turpen Sheila L , Englund Matthew A , Piekarski Witold 
Published: March 2010

AbstractA 7-d growth and survival toxicity test using the west coast marine mysid crustacean Holmesimysis costata (Holmes) was evaluated to determine test precision and sensitivity. The intralaboratory coefficient of variation (CV) among six reference toxicant test median lethal concentrations (LC50s) was 25%, whereas the mean intralaboratory CV for side-by-side effluent test LC50s was 7%. The mean intralaboratory CV for the concentration at which growth was inhibited by 25% (IC25) was 19%. Interlaboratory CVs for effluent LC50s averaged 14%, whereas variation among growth IC25s averaged 15%. Test precision and sensitivity compared favorably with literature values for a number of commonly used toxicity tests and chemical methods. Toxicity increased slightly with increased mysid exposure from 4 to 7 d (mean effluent LC50s of 9.9% for 4 d of exposure and 7.5% for 7 d), and more significantly from 7 to 24 d (zinc LC50 values were 50 μg/L and 7.8 μg/L for concurrent 7-d and 24-d tests). Although growth was a less sensitive endpoint than survival in tests with individual chemicals (zinc and sodium azide), growth was the more sensitive endpoint in seven of nine tests with complex effluents. Seventy-five percent of tests conducted at all participating laboratories met protocol test acceptability criteria (n = 40).
Effects of acute 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure on plasma thyroid and sex steroid hormone concentrations and estrogen receptor levels in adult great blue herons
Authors: Janz David M , Bellward Gail D 
Published: March 2010

Abstract
Adult great blue herons (Ardea herodias) were exposed intraperitoneally to a single dose of 20 μg/kg body weight of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and sacrificed after 14 d. Approximately 1.9% of the total TCDD dose was measured in the liver. No differences were found in liver weight or liver to body weight ratio between control and TCDD-treated birds. Hepatic microsomal ethoxyresorufin O-deethylase (EROD) activity was induced sixfold above control activities in TCDD-exposed herons (p &lt; 0.001). Plasma total T4 concentration was significantly elevated in TCDD-exposed herons (p &lt; 0.05). The TCDD treatment had no effect on plasma total T3 levels, or on the plasma T3 to T4 ratio. No effect of this TCDD exposure was found on plasma 17β-estradiol or testosterone concentrations, or on hepatic estrogen receptor affinities and concentrations is male or female herons.
Advances in forensic toxicology for establishing causality between Great Lakes epizootics and specific persistent toxic chemicals
Authors: Gilbertson Michael 
Published: March 2010

Abstract
Populations of fish, wildlife, and humans in the Great Lakes basin have been injured during this century by exposures to organochlorine pollutants. The evidence presented by scientists working on these outbreaks of chemically induced disease has been received with scepticism among officials, who have expressed a desire for a “proven” cause and effect before further costly regulatory and remedial action is taken. Scientists have adapted epidemiological criteria to infer causal relationships between the injury and exposures to specific chemicals. These forensic statements are different from traditional toxicological statements about potential effects. There is a priority need to institutionalize this methodology within governments to complement established risk assessment techniques.
The use of nontraditional assays in an integrated environmental assessment of contaminated ground water
Authors: Twerdok Lorraine E , Burton Dennis T , Gardner Henry S , Shedd Tommy R , Wolfe Marilyn J 
Published: March 2010

Abstract
The toxic potential of ground water contaminated with several probable carcinogenic heavy metals and halogenated solvents was evaluated using an integrated environmental assessment approach. A number of assays, which included acute toxicity, short-term chronic toxicity, genotoxicity, developmental toxicity and carcinogenicity, were used to assist in a hazard assessment. Comprehensive analytical chemistry was performed throughout the 9-month exposure to document the chemical characteristics of the ground water. An initiation-promotion protocol using a non-neoplastic concentration of diethylnitrosamine as an initiator in a 9-month chronic exposure of Japanese medaka (Oryzias latipes) was used to evaluate potential carcinogenicity of the ground water. The fish were exposed to groundwater concentrations of 1% and 10% ground water by volume. No significant lesions were found in the Japanese medaka exposed to groundwater concentrations at 1% or 10% ground water by volume. Likewise, no genotoxicity, developmental toxicity, acute toxicity or short-term chronic toxicity, were found at concentrations of ≤10% ground water by volume. The negative results obtained in this study show that the potential hazard posed by low concentrations of a complex mixture containing suspect carcinogens may not be manifested at environmentally relevant concentrations.
Major ion toxicity of six produced waters to three freshwater species: Application of ion toxicity models and tie procedures
Authors: Tietge Joseph E , Hockett J Russell , Evans James M 
Published: March 2010

Abstract
Previous research to characterize the acute toxicity of major ions to freshwater organisms resulted in the development of statistical toxicity models for three freshwater species (Ceriodaphnia dubia, Pimephales promelas, and Daphnia magna). These ion toxicity models estimate the toxicity of seven major ions utilizing logistic regression. In this study, the ion toxicity models were used in conjunction with Phase I toxicity identification evaluation (TIE) procedures to evaluate the contribution of major ion toxicity to the total toxicity of six produced water samples ranging in total salinity from 1.7 to 58.1 g/L. Initial toxicities of all six samples were compared to the model predictions. Four produced waters were found to have toxicity consistent with toxicity attributable to major ion concentrations only. Two produced waters were found to exhibit more toxicity than expected from ion concentrations alone. These samples were subjected to Phase I TIE procedures. Toxicities were reduced by specific Phase I TIE manipulations to those predicted by the ion toxicity models. Mock effluents were used to verify the results. The combination of the ion toxicity models with Phase I TIE procedures successfully quantified the toxicity due to major ions in six produced water sample.
Error propagation in fugacity level-III models in the case of uncertain physicochemical compound properties
Authors: Kühne Ralph , Breitkopf Cornelia , Schüürmann Gerrit 
Published: March 2010

Abstract
For a level-III fugacity model to predict the steady-state environmental distribution of chemicals on a regional scale, the effect of erroneous physicochemical input data on the model output was studied using Monte Carlo simulations. Uncertainty analyses were performed for the octanol/water partition coefficient and Henry's law constant with assumed standard errors of 0.5 and 0.1 log units according to corresponding Gauss distributions, using phenol, pentachlorophenol, ethanol, acetone, and anthracene as model compounds. The results showed considerable variations of factors up to 2.5 for the predicted relative distributions among the major compartments. The output variations were greater for compounds with more than one sink. The results demonstrate the need for addressing error propagation in multimedia models in a systematic way.