bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toxicity of inorganic and organic selenium to Daphnia magna (cladocera) and Chironomus riparius (diptera)
Authors: Ingersoll C. G. , Dwyer F. J. , May T. W. 
Published: March 2010

Abstract
Elevated concentrations of selenium (Se) have been previously measured in biota sampled from the Kesterson National Wildlife Refuge (KNWR) in the San Joaquin Valley of central California. We conducted acute and chronic toxicity tests with the cladoceran Daphnia magna and the midge Chironomus riparius to determine the toxicity or bioaccumulation of waterborne Se in a reconstituted water similar to the San Joaquin River. Daphnids were more acutely sensitive than midges to the toxic effects of inorganic Se. An organic form of Se (seleno-[L]-methionine) was extremely toxic to daphnids, but was relatively nontoxic to midges. In long-term exposure to a 6:1 mixture of selenate to selenite (a mixture representative of KNWR), the emergence time of adult midges was delayed at Se concentrations ≥ 837 μg/L. Daphnid reproduction and intrinsic rate of natural increase (r) were reduced at Se concentrations ≥ 348 μg/L and growth of adults was reduced at ≥ 156 μg/L. Whole body Mg, K and Na concentrations in daphnids were not affected by chronic Se exposure; however, whole body Ca concentration increased at intermediate Se exposure concentrations. In addition, whole body Cl concentration was reduced at 711 μg Se/L. Daphnids accumulated potentially toxic concentrations of Se from water that may adversely affect fish or waterfowl through the food chain.
Simplification of in vitro culture techniques for freshwater mussels
Authors: Keller Anne E. , Zam Stephen G. 
Published: March 2010

Abstract
Populations of freshwater mussels have been declining for several decades due to habitat destruction, pollution and sedimentation. Efforts to propagate rare and endangered species in the laboratory have been hampered by their need for fish as hosts during a brief parasitic phase in early development and more recently, by cumbersome alternative methods. The methods developed here are simple and use common tissue culture products that standardize the procedures allowing production of large numbers of juvenile mussels for replenishment of wild mussel populations or for use in toxicity testing protocols. Anodonta imbecilis, Lampsilis teres and Villosa lienosa have been successfully propagated using these methods.
Effects of selected PCB congeners on survival, growth, and reproduction inDaphnia magna
Authors: Dillon Tom M. , Benson William H. , Stackhouse R. Allan , Crider A. Michael 
Published: March 2010

AbstractThe effects of individual polychlorinated biphenyl (PCB) congeners on survival, growth and reproduction in the freshwater cladoceran, Daphnia magna, were determined. Congeners evaluated in this study (IUPAC numbers 52, 77, 101, 118, 138, 153, 180) represent a variety of microsomal mixed-function oxidase (MFO) inducers. After 21 d of static renewal exposure, Daphnia survival was high (88–100%) in all congener treatments and unaffected by any PCB. Polychlorinated biphenyl congeners had little to no detectable sublethal effects on reproduction and growth. The number of neonates produced was either unaffected (congeners 52, 77, 118) or enhanced (congeners 101, 138, 153, 180). Effects on total biomass were mixed and the magnitude of significant differences, when observed, was small. Diminished biomass was observed in Daphnia exposed to congener 101 whereas increases occurred in treatments with congeners 52 and 118. Both elevated and diminished biomass was observed in animals exposed to congener 77. Congeners 138, 153 and 180 had no significant effect on Daphnia biomass.Daphnia accumulated substantial amounts of all PCBs even though minimal effects on survival, growth and reproduction were observed. Mean tissue concentrations ranged from approximately 2.0 ng/mg to 130 ng/mg dry weight. These tissue residues are one to several orders of magnitude greater than those observed in aquatic fish and invertebrates collected in and around industrial waterways of the Great Lakes. Possible explanations for the lack of PCB congener toxicity are discussed.
The octanol/water partition coefficient of methylmercuric chloride and methylmercuric hydroxide in pure water and salt solutions
Authors: Major Michael A. , Rosenblatt David H. , Bostian Karen A. 
Published: March 2010

Abstract
The 1-octanol/water partition coefficient (Kow) of methylmercury was determined at pH 7 in water and in aqueous solutions ranging from 0.0003 to 0.6000 M in sodium chloride. It was also determined over a pH range of 2 to 10 with a fixed sodium chloride concentration of 0.0045 M. In these experiments, Kow was seen to increase with increasing chloride concentrations in the range 0.0 to 0.075 M and to decrease with increasing pH above 7. Results were similar whether low levels of methylmercuric chloride or methylmercuric hydroxide were used as the starting materials. Partitioning was not affected by changes in ionic strength.
Routes of uptake and their relative contribution to the toxicologic response of Northern bobwhite (Colinus virginianus) to an organophosphate pesticide
Authors: Driver Crystal J. , Drown David B. , Ligotke Michael W. , Van Voris Peter , McVeety Bruce D. , Greenspan Bernard J. 
Published: March 2010

Abstract
Ingestion of contaminated food is considered the primary route of exposure in birds to agricultural chemicals. Routes of exposure other than ingestion are not often considered in risk assessments of agricultural chemicals to avian wildlife. However, recent studies demonstrated anorexic or avoidance behaviors in birds exposed to organophosphate (OP) insecticides. These behaviors would tend to limit exposure if ingestion alone were considered. The contribution, if any, of dermal, preening, and respiratory pathways to the exposure of birds to pesticides under field conditions is unknown. In addition, oral exposures are currently assessed in artificial environments that do not reflect real-life exposure scenarios. To determine the relative contribution of these pathways and to assess exposures under ecological conditions, 270 northern bobwhite (Colinus virginianus) were exposed to simulated aerial crop applications of methyl parathion in an environmentally controlled wind tunnel. The wind tunnel environment consisted of a 25-cm cotton plant canopy, a 5-cm-thick floor of silt-loam, a temperature of 25°C, 50% RH, UV intensity similar to summer sunlight, and a wind speed of 3.2 km/h. Inhalation, preening, and dermal routes were isolated in groups of birds exposed to each application. Five birds from each group were collected at 1, 4, 8, 24, and 48 h post-spray to determine cholinesterase (ChE) response to the exposures. Contaminated and uncontaminated darkling beetle (Tenebrio molitar) larvae were presented to free-ranging sprayed birds in the wind tunnel to assess oral uptake. ChE response was determined at 4, 8, 24, and 48 h postspray. All exposures were replicated. All four routes contributed to the inhibition of brain ChE at different post-spray periods. Dermal uptake and preening were major contributors to the overall dose and toxic response of birds to methyl parathion. Inhalation was the major route of exposure at 1 h post-spray. At 4 h post-spray, uptake through preening caused the greatest inhibition of brain ChE activity. Oral ingestion resulted in less than 20% inhibition of brain ChE during the test. Routes of uptake in order of contribution to toxicologic response from 8 to 48 h post-spray were dermal &gt; preening ≥ oral &gt; inhalation.
Toxicokinetics and toxicity of a mixture of sediment-associated polycyclic aromatic hydrocarbons to the amphipod Diporeia sp
Authors: Landrum Peter F. , Eadie Brian J. , Faust Warren R. 
Published: March 2010

Abstract
Amphipods, Diporeia sp., were exposed to a reference sediment dosed with two radiolabeled polycyclic aromatic hydrocarbons (PAHs) and sediments dosed with a mixture of PAHs at four concentrations: 21.4, 41.0, 119.6, and 327.0 nmol g−1 dry sediment, as the molar sum of the PAH congeners. Diporeia sp. were sampled for mortality and toxicokinetics for up to 26 d. Significant sediment avoidance was observed at the highest dose out to 6 d of exposure. The toxicity for the mixture was 38 ± 3% after 19 d of exposure at the highest dose, 327 nmol g−1 dry sediment as the molar sum of the PAHs. The measured organism concentration required to produce the mortality at day 19 was 2.9 μmol g−1 as the sum of the bioaccumulated PAHs. The uptake clearance (g dry sediment g−1 organism h−1) from sediments for the radiotracers increased with dose to an apparent plateau. Uptake clearance is the conditional constant relating the contaminant flux into the organism to the contaminant concentration in the referenced environmental compartment, in this case the sediment. This enhanced bioavailability with dose occurred even in the absence of overt effects and in the absence of changes in the measured partition coefficients for phenanthrene (273 ± 98) and pyrene (540 ± 212), between the freely dissolved radiotracers in interstitial water and the sediment particles. These changes in bioavailability with changes in PAH concentration suggest that predictions of bioaccumulation of PAH congeners from sediments under different field concentration conditions will not be possible with standard partitioning relationships.
Mitochondrial response to chlorophenols as a short-term toxicity assay
Authors: Shannon Robert D. , Boardman Gregory D. , Dietrich Andrea M. , Bevan David R. 
Published: March 2010

Abstract
In this investigation the effects of chlorophenols on rat liver mitochondrial respiratory parameters were determined and compared to the toxicities of those compounds in a variety of biological systems currently being used for toxicity testing. Mitochondrial fractions were exposed to six concentrations of five different chlorophenols in a semiclosed, 2-ml reaction vessel. Respiratory parameters were measured polarographically with an oxygen electrode and compared to control experiments. The toxicity of the chlorophenols, as measured by the concentration reducing the respiratory control ratio of the control to 50% (RCR50), increased with increasing chloro substitution. RCR50 concentrations ranged from 599 μM with 2-chlorophenol to 0.110 μM with pentachlorophenol.
The RCR50 concentrations for the five chlorophenols were compared to six physicochemical parameters for the same chlorophenols; high degrees of correlation between the RCR50 concentrations and the physicochemical parameters were found (r ≥ 0.890). The highest correlation coefficient obtained was with the n-octanol/water partition coefficient (r = 0.991), indicating that the ability of chlorophenols to partition into the lipid mitochondrial membrane plays a significant role in eliciting its toxic effect. RCR50 concentrations were also compared to nine currently existing short-term toxicity tests. High degrees of correlation were obtained with several of the tests, including algal, bacterial, and fish bioassays. This suggests that the uncoupling of oxidative phosphorylation may be the major mechanism by which chlorophenols cause toxicity to intact cells as well as more complex organisms.
The use of mitochondrial respiratory parameters appears to offer a complementary approach as a short-term toxicity test for this class of compounds. Further development and testing with a variety of other toxicants is suggested.
A four-day survival and reproduction toxicity test for ceriodaphnia dubia
Authors: Oris James T. , Winner Robert W. , Moore Marianne V. 
Published: March 2010

Abstract
A 4-d survival and reproduction toxicity test utilizing Ceriodaphnia dubia has been developed and evaluated. This toxicity test has been compared to the standard 7-d test using a total of 12 toxicants encompassing a wide range of chemical classes. In addition, 48-h LC50 values were determined for each chemical in the absence of food. Four-day and seven-day tests were run concurrently, twice for each chemical. Less-than-12-h-old neonates for both 4-d and 7-d tests were segregated into individual test cups on Fridays. Animals for 7-d tests were immediately exposed to the test chemical. Animals for 4-d tests were held in control water and not exposed to the test chemical until day 3. Animals were fed daily and solutions were changed on Mondays and Wednesdays. Chemical concentrations were measured by appropriate analytical techniques during each test. Survival and mean total young per female were used to compare the relative sensitivity of the 4-d and 7-d tests. Data were analyzed using traditional hypothesis testing techniques to determine chronic values from the no-observed- and lowest-observed-effect concentrations. In addition, data were analyzed using a nonparametric, monotonic smoothing technique to determine interpolated point estimates and 95% confidence intervals for the 50% inhibition concentration (IC50). Comparisons between the 4-d test versus the 7-d test for both methods of data analysis indicated that the 4-d test provides an acceptable level of sensitivity in the toxicity testing of single compounds.
Brain cholinesterase activity of bobwhite acutely exposed to chlorpyrifos
Authors: Cairns Michael A. , Maguire Christine C. , Williams Bill A. , Bennett Jewel K. 
Published: March 2010

Abstract
Northern bobwhite, Colinus virginianus, were orally dosed with the organophosphorus insecticide chlorpyrifos to examine effects on brain chohnesterase (ChE) activity. Two-week-old quail were acutely exposed and euthanized at selected times following gavage-dosing, ranging from I to 120 h later. The ChE activity was determined in treated birds and compared to concurrently tested control (corn oil) birds. It was found that a lag time of 2 to 4 h following exposure was necessary to detect significant ChE depression caused by chlorpyrifos. The lowest dose that produced ChE depression in these tests was between —30 and 50 mg chlorpyrifos/kg body weight, with some mortality occurring at the high end of that range. Depression typically persisted for at least 24 h.
Long-term persistence of polychlorinated biphenyl congeners in blood and liver and elevation of liver aminopyrine demethylase activity after a single high dose of aroclor 1254 to mice
Authors: Anderson Lucy M. , Dixon Dwayne , Beebe Lisa E. , Fox Steven D. , Issaq Haleem J. 
Published: March 2010

Abstract
Poorly metabolized polychlorinated biphenyl (PCB) congeners are bioaccumulated in the bodies of rodents and humans. Little is known about the continuing biological effects of these persistent chemicals. To determine whether a single high dose of a PCB mixture to mice would have long-term effects on liver enzymes, Aroclor 1254 was given at a single dose of 500 mg/kg to (C57BL/6 × DBA/2)F1 female mice. Paired controls received olive oil. Mice were killed at intervals of 0.5 to 55 weeks after treatment and liver assessed for aminopyrine demethylase activity. At selected time points, blood and homogenates of liver and of whole carcass were analyzed for content of PCBs by gas chromatography with electron capture detection. Hepatic aminopyrine demethylase activity was significantly elevated in Aroclor-treated mice, relative to controls, for 42 weeks after treatment. A three- to fourfold increase persisted for at least 14 weeks, with a convergence of treated and control values thereafter. Significant amounts of nine PCB congeners were detected in carcass, liver, and blood; total carcass PCB, estimated on the basis of these congeners, correlated significantly with liver aminopyrine demethylase elevation, and a similar trend was noted for liver. At 42 weeks after treatment, total PCB levels were 70 mg/kg for carcass, 2.4 mg/kg for liver and 0.28 mg/kg for blood. Congener profiles were similar in all three compartments, with the majority of the retained chemical being 2,3′,4,4′,5- and 2,3,3′,4,4′-pentachlorobiphenyl and 2,2′,4,4′,5,5′-and 2,2′,3,4,4′,5′-hexachlorobiphenyl. These results suggest that congeners bioaccumulated after a high PCB dose retain biological activity in the body for nearly a year after treatment.
Biological and biochemical effects of retained polyhalogenated hydrocarbons
Authors: Beebe Lisa E. , Anderson Lucy M. , Fox Stephen D. , Issaq Haleem J. 
Published: March 2010

AbstractThe polyhalogenated aromatic hydrocarbons (PHHs), consisting of the chlorinated and brominated biphenyls, dibenzo-p-dioxins and dibenzofurans, are important environmental contaminants affecting both wildlife and humans. Although the biological effects due to acute or chronic exposure to these compounds have been extensively investigated with animal models, relatively little is known concerning the long-term ramifications of such exposure due to the persistent body burdens of some PHH congeners. This review examines the persistent effects of these contaminants for two biological end points: tumor formation and induction of cytochrome P-450-associated mixed function oxygenases in target tissues. Literature and data are presented that indicate that retained PHH congeners continue for many months to exert biological effects that contribute to tumor development in rodent livers and lungs. Effects of specific congeners, retention profiles of these congeners in target tissues and the long-term induction of cytochrome P-450 IA1-associated enzyme activity are all consistent with activation of the Ah receptor's being an integral part of the tumor promotion response.
Effects of a contaminated sediment on life history traits and population growth rate of Neanthes arenaceodentata (polychaeta: Nereidae) in the laboratory
Authors: Pesch Carol E. , Munns Wayne R. , Gutjahr-Gobell Ruth 
Published: March 2010

Abstract
The effects of a highly contaminated sediment on life history traits and population dynamics of the nereid polychaete. Neanthes arenaceodentata Moore were assessed in a laboratory experiment Survival, growth and fecundity were measured for one generation of worms exposed to 40 and 10% Black Rock Harbor, Connecticut (BRH) sediment (a contaminated sediment), 100% reference (REF) sediment from central Long Island Sound (the control) and a no-sediment treatment (to follow progress of pairing and reproduction) The BRH sediment did not affect survival or size of adults or number of broods Number of eggs per brood appeared to be lower in 40% BRH sediment than 10% BRH or REF sediment, but the difference was not significant (1,397, 1,621 and 1,556 eggs per brood, respectively) However, number of larvae per brood was significantly lower in the 40% BRH sediment than in 10% BRH or REF sediment (363, 770 and 850 larvae per brood, respectively) Number of juveniles appeared to be lower in 40% BRH than in the other sediment treatments, although the differences were not significant Size of juveniles did not differ in the sediment treatments The finite multiplication rate of population increase, λ, was the same for all treatments The lack of significant differences but the presence of some trends may indicate that 40% BRH sediment was not a high enough dose to produce significant effects Effects of BRH sediment on other species are discussed. In conjunction with an earlier study, this work demonstrates that population responses of life cycle tests with Neanthes arenaceodentata can be used to evaluate the chronic toxicity of sediments, which could provide comparative toxicological data to evaluate the relative sensitivity of this and other marine species and may serve as a model system to study questions in population biology
Uncertainty in ocean-dumping health risks: Influence of bioconcentration, commercial fish landings and seafood consumption
Authors: Lipton Joshua , Gillett James W. 
Published: March 2010

Abstract
Human consumption of marine organisms that have been contaminated by ocean disposal of municipal sewage sludges may pose significant health risks. Previous models of ocean dumping health risk, however, have failed to assess uncertainties associated with model parameters. This failure has resulted in risk assessments that may be misleading to policymakers. Uncertainties regarding contaminant bioaccumulation, commercial fish landings and seafood consumption were incorporated into a model of carcinogenic health risk for two materials found in municipal sewage sludges, dichlorodiphenyltrichloroethane and metabolites (DDT-R) and polychlorinated biphenyls (PCBs). Iterative Latin hypercube simulation was employed to generate probability distributions of health risks. Results indicate that parameter variability and uncertainty, particularly in bioaccumulation models, can lead to a several-orders-of-magnitude range in estimated risk values. This distributional range straddles current risk-management thresholds, suggesting that ocean disposal of municipal sludges may, indeed, pose substantial health risks to seafood consumers under certain sets of conditions and assumptions. Moreover, if not explicitly considered in risk models, uncertainty can lead to errors in risk-based decision making.
The relationship of parathion concentration, exposure time, cholinesterase inhibition and symptoms of toxicity in midge larvae (chironomidae: Diptera)
Authors: Detra Randall L. , Collins William J. 
Published: March 2010

Abstract
Larvae of Chironomus riparius were used to demonstrate a statistically significant relationship between four variables: parathion concentration in water (nominally 20 to 500 μg/L), duration of exposure, symptoms of toxicity, and in vivo cholinesterase (ChE) inhibition. The symptoms of toxicity were a series of swimming behaviors that were categorized and assigned numerical values according to intensity of poisoning. These values were correlated with ChE inhibition by a polynomial regression. Therefore, symptoms of poisoning could be mathematically estimated from measurements of percent ChE inhibition. A three-dimensional relationship between ChE inhibition, the logarithm of exposure time, and the logarithm of parathion concentration was established. This permits the characterization of the range of conditions for the onset of a given toxicity symptom and also predicts the symptom for which values for at least two of these variables are provided.
Optimizing btex biodegradation under denitrifying conditions
Authors: Hutchins Stephen R. 
Published: March 2010

Abstract
Laboratory tests were conducted to determine optimum conditions for benzene, toluene, ethylbenzene, and xylene (collectively known as BTEX) biodegradation by aquifer microorganisms under denitrifying conditions. Microcosms, constructed with aquifer samples from Traverse City, Michigan, were amended with selected concentrations of nutrients and one or more hydrocarbons. Toluene, ethylbenzene, m-xylene, and p-xylene were degraded to below 5 μg/L when present as sole source substrates; stoichiometric calculations indicated that nitrate removal was sufficient to account for 70 to 80% of the compounds being mineralized. o-Xylene was recalcitrant when present as a sole source substrate, but was slowly degraded in the presence of the other hydrocarbons. Benzene was not degraded within one year, regardless of whether it was available as a sole source substrate or in combination with toluene, phenol, or catechol. Pre-exposure to low levels of BTEX and nutrients had variable effects, as did the addition of different concentrations of ammonia and phosphate. Nitrate concentrations as high as 500 mg/L NO3-N were slightly inhibitory. These data indicate that nitrate-mediated biodegradation of BTEX at Traverse City can occur under a variety of environmental conditions with rates relatively independent of nutrient concentrations. However, the data reaffirm that benzene is recalcitrant under strictly anaerobic conditions in these samples.