bluuebunny/crossref_metadata_2025_split huggingface dataset:
Embryotoxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the ring-necked pheasant
Authors: Nosek John A. , Craven Scott R. , Sullivan John R. , Gendron-Fitzpatrick Annette , Peterson Richard E. 
Published: March 2010

AbstractFertilized eggs of ring-necked pheasants (Phasianus colchicus) were injected into the albumin or yolk with vehicle or graded doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (0.01, 0.1, 1, 10, 100, 1,000, 10,000, or 100,000 pg TCDD/g egg) on day 0 of embryonic development and toxicity was assessed in 1-d-old hatchlings and 28-d-old chicks. The most sensitive effect of in ovo TCDD exposure was induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity in 1-d-old hatchlings. The ED50 for this response was 312 pg TCDD/g egg. Embryo mortality was the most sensitive sign of toxicity. The TCDD dose that caused 50% mortality above control (LD50) when injected into the egg albumin or yolk was 1,354 and 2,182 pg TCDD/g egg, respectively. At egg TCDD doses up to and including 1,000 pg TCDD/g egg, no effect was detected in 1-d-old hatchlings and 28-d-old chicks in body growth, organ weights, carcass morphometrics, incidence of edema, or incidence of histological alterations in the liver, spleen, heart, Bursa of Fabricius, or thymus. Egg TCDD doses as high as 1,000 pg TCDD/g egg also had no effect on cardiac morphometrics or incidence of cardiac malformations in 1-d-old hatchlings, or on antibody-mediated immunity in 28-d-old chicks. We conclude that embryo mortality is the most sensitive sign of TCDD toxicity in the ring-necked pheasant following in ovo exposure. The ring-necked pheasant embryo is less sensitive than the chicken (Gallus domesticus) embryo and more sensitive than the eastern bluebird (Sialia sialis) embryo to TCDD toxicity.
Sensitivity of early-life-stage golden trout to low pH and elevated aluminum
Authors: Delonay Aaron J. , Little Edward E. , Woodward Daniel F. , Brumbaugh William G. , Farag Aida M. , Rabeni Charles F. 
Published: March 2010

Abstract
Early-life-stage golden trout (Oncorhynchus aguabonita aguabonita) were exposed to acid and Al to examine the response and determine the sensitivity of a western, alpine salmonid to conditions simulating an episodic pH depression. Freshly fertilized eggs, alevins, and swim-up larvae were exposed for 7 d to one of 12 combinations of pH and Al, and surviving fish were held to 40 d post-hatch to determine the effect of exposure on subsequent survival and recovery. Golden trout are sensitive to conditions simulating episodic acidification events typically observed in the field. Significant mortality occurred when the pH of test waters was below 5.0 in the absence of Al or when pH was 5.5 in the presence of 100 μg/L total Al. Behavioral impairments were sensitive indicators of low pH and Al stress. Impaired locomotory and feeding behavior occurred at pH 5.5 without Al and at Al concentrations &gt; 50 μg/L. In contrast, growth, RNA-to-DNA ratio, and whole-body ion concentration were relatively less sensitive indicators of sublethal acid and Al stress.
Quantitative structure-activity relationships for predicting the toxicity of pesticides in aquatic systems with sediment
Authors: Fisher S.W. , Lydy M.J. , Barger J. , Landrum P.F. 
Published: March 2010

Abstract
The toxicity of a series of organophosphorus (OP) and carbamate insecticides was measured against the midge Chironomus riparius in aquatic systems with and without sediment. Five molecular descriptors (molecular volume, Henry's law constant, n-octanol/water partition coefficient (Kow), molecular connectivity, and linear solvation energy) were used in regression analysis as potential predictors of insecticidal activity. The regressions were conducted for each descriptor against toxicity values for the series of chemicals.
Molecular volume and Henry's law constant showed no relationship with toxicity. However, log Kow was moderately successful in describing the effect of sediment on toxicity (r2 = 0.508). Prediction of toxicity was substantially improved when a linear solvation energy (LSE) or molecular connectivity (MC) model was used in regressions. In multiple regressions conducted on carbamates and OPs separately, use of MC or LSE parameters explained up to 95.8% of the variability in toxicity. Based on the results of regression analyses, sorptive interactions between these insecticides and sediment apparently dominate the processes affecting the toxicity of these compounds when sediment is present. In the absence of sediment, the regressions suggest that the molecular structure of the insecticides is more important than solubility or partitioning for determining toxicity.
Environmental science and resource management in the 21st century: Scientific perspective
Authors: Cairns John 
Published: March 2010

Abstract
Ecotoxicology in the 21st century will be part of the larger field of integrated environmental science and resource management. This already established trend has some main impetuses: (a) A definite shift is occurring from only protecting against toxic damage to ensuring robust ecosystem health or condition; (b) the modus operandi of the information age is integrative science, not fragmented science; (c) the most exciting discoveries are occurring at the interfaces of the classical disciplines; (d) the preoccupation with “end-of-the-pipe” waste discharges is rapidly shifting to a system-level or landscape-level perspective; and (e) the professional societies that miss the beginnings of major trends can partially offset this loss by establishing close relationships with the new societies that are riding the crest of the “waves.” It will be extremely important for both individual professionals and professional societies to respond to these rapid changes. Otherwise, individuals will be left in the professional backwaters, and professional societies will be replaced by more agile young societies in the same way that SETAC had its genesis.
Effects of age, species difference, antibiotics and toxicants on intestinal enzyme activity and genotoxicity
Authors: Chadwick R. W. , George S. E. , Kohan M. J. , Allison J. C. , Chang J. , Long J. E. , Duffy M. C. , Dekker J. P. , Forehand L. R. 
Published: March 2010

Abstract
Altered intestinal enzyme activity significantly affects the biotransformation and toxicity of many xenobiotics. This article summarizes research, supported by the U.S. Air Force Bioenvironmental Hazards Research Program, that employs a novel gas-liquid chromatographic assay to investigate the effects of age, species difference, antibiotics, and environmental chemicals on enzyme activity in various regions of the intestinal tract. Significant research findings include the following: (a) age-dependent alterations in enzyme activity in the gastrointestinal (GI) tract of the developing animal that suggest a changing susceptibility to toxicants during this period; (b) discovery of previously unreported mucosal enzymes in the small intestine that are present in germ-free rats and are not susceptible to antibiotics; (c) markedly greater intestinal nitroreductase activity and significantly higher bioactivation of the procarcinogen 2,6-dinitrotoluene (DNT) in CD-1 mice than in Fischer 344 rats; (d) significantly altered intestinal enzyme activity in rats pretreated with lindane, pentachlorophenol, 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), or Aroclor 1254; (e) potentiated DNT genotoxicity by Aroclor 1254 and pentachlorophenol pretreatment; and (f) a transient antagonism of DNT genotoxicity by 2,4,5-T pretreatment. Enzyme activity in the small intestine may have greater toxicological importance than previously thought in the biotransformation of environmental chemicals and as an indicator of change in the microbial flora.
Biochemical and mutagenic characterization of plant-activated aromatic amines
Authors: Plewa Michael J. , Gichner Tomáš , Xin Hua , Seo Kwang-Young , Smith Shannon R. , Wagner Elizabeth D. 
Published: March 2010

Abstract
Plant activation is the process by which promutagenic agents are activated into rautagens by plant systems. With the widespread use of agricultural chemicals on crop plants and with the global exposure of plants to pollutants, the possibility exists that plant-activated agents may be introduced into the human food chain. The plant cell/microbe coincubation assay uses cultured plant cell suspensions as the activating system and bacteria or yeast cells as the genetic indicator organism. After a treatment time, the microbes are plated on selective medium. In this way the activation system and the genetic system can be independently studied. In addition, the viability of the plant cells and the microbial cells can be independently determined so that the toxicity of a test agent can be evaluated. Using cytochrome P450 monooxygenase and peroxidase inhibitors, we are studying the biochemical mechanisms of plant activation of environmental contaminants, especially aromatic amines. We propose a working model for the activation of aromatic amines by cultured tobacco cells into stable frameshift mutagens.
Effects of auxiliary carbon sources and electron acceptors on methanogenic degradation of chlorinated phenols
Authors: Häggblom Max M. , Rivera Maria D. , Young L. Y. 
Published: March 2010

Abstract
We studied the degradation of chlorinated phenols under methanogenic conditions by establishing enrichment cultures on 4-chlorophenol and 2,4-dichlorophenol with or without a supplementary substrate. p-Cresol was chosen as a nonchlorinated aromatic compound structurally similar to the chlorophenols, and propionate was chosen as a readily utilizable carbon source. 2,4-Dichlorophenol was dechlorinated to 4-chlorophenol, which was degraded without further detection of metabolites. The rates of chlorophenol metabolism were enhanced by subsequent refeeding of the respective chlorophenols and supplementary substrates. The addition of p-cresol or propionate as an auxiliary carbon source enhanced the rate of 4-chlorophenol degradation. Methanogenic cultures capable of ortho dechlorination were repeatedly subcultured by dilution into fresh media and refeeding of 2,6-dichlorophenol and either p-cresol or propionate as auxiliary substrates. 2,6-Dichlorophenol was sequentially dechlorinated to 2-chlorophenol and phenol and ultimately mineralized to methane and carbon dioxide. Cultures adapted to 2,4- or 2,6-dichlorophenol also readily dechlorinated other dichlorophenols containing an ortho chlorine. The alternative electron acceptors nitrate, sulfite, and thiosulfate completely inhibited dechlorination of 2,6-dichlorophenol, whereas sulfate slowed the dechlorination rate.
Sorption of chlorobenzenes to mineralizing phytoplankton
Authors: Koelmans Albert A. , Lijklema Lambertus , Jiménez Carmen Sánchez 
Published: March 2010

Abstract
The influence of mineralization of phytoplankton (laboratory Scenedesmus spp.) on the desorption characteristics of 1,2,3,4-tetrachlorobenzene (TeCB) and hexachlorobenzene (HCB) was studied using a purge and trap method. For comparison several field samples, including a sediment, algae at different growth stages, and freeze-dried algae, were used. The desorption characteristics were evaluated using multiple box models similar to those generally used for desorption from sediments. It was found for all adsorbents that the desorption could adequately be described using a two-compartment nonequilibrium biosorption model. Generally, HCB was bound more strongly and released more slowly than TeCB. Aging and mineralization of unicell and coenobian forms of the algal species resulted in a significant 60 to 100% increase of OC-normalized partition coefficients. Generally, sorption affinity as quantified by the OC-normalized partition coefficient (K, oc) was lower, and desorption kinetics faster for algae than for soils and sediments. Evaluation of the biosorption rate parameters using a log k2 vs. log Kp plot showed that in contrast to sediments and soils, no clear inverse relationship between Kp and k2 exists. A bioconcentration experiment with four chlorobenzenes showed good agreement with the sorption parameters measured with the purge method, and showed a linear correlation of the bioconcentration factor with the octano1/water partition coefficient.
Acute toxicity of the herbicide bromoxynil to Daphnia magna
Authors: Buhl Kevin J. , Hamilton Steven J. , Schmulbach James C. 
Published: March 2010

Abstract
The acute toxicities of technical-grade bromoxynil octanoate (BO) and two commercial formulations, Buctril® and Bronate®, to &lt; 24-h-old neonate Daphnia magna (Straus) were determined in soft, hard, and oligosaline water. In addition, effects of life stage, feeding, aging the herbicide, and exposure duration on BO toxicity to daphnids were investigated. Regardless of formulation, life stage, and water quality, BO was found to be extremely to highly toxic to daphnids in standard tests; 48-h EC50 values ranged from 41 to 161 m̈g/L. Bromoxynil octanoate was the most toxic to neonates in soft water and the least toxic in hard water. The acute toxicities of the three bromoxynil herbicides to a given age group of daphnids were similar within the same water type. Overall, neonates and 7-d-old adults were more sensitive than 14- or 15-d-old adults to each herbicide. Feeding daphnids during the toxicity test significantly decreased BO toxicity compared to not feeding them. Aging BO (as Buctril) in hard water decreased its toxicity, and the rate of deactivation was rapid, with an estimated half-life of biological activity of 13 h. Daphnids immobilized by exposures to toxic BO concentrations for ≤ 6 h recovered their mobility, whereas exposures of 18 and 24 h to BO produced toxic effects in daphnids similar to those exposed for 48 h. These results indicated that standard continuous exposure tests may not adequately predict the acute toxicity of BO to freshwater animals in the field.
Absorption, tissue distribution and metabolism of chlorpyrifos in channel catfish following waterborne exposure
Authors: Barron Mace G. , Plakas S. M. , Wilga P. C. , Ball T. 
Published: March 2010

Abstract
The pharmacokinetics, tissue distribution, and metabolism of waterborne chlorpyrifos were investigated in channel catfish (Ictalurus punctatus) fitted with arterial and urinary catheters. Pharmacokinetic analysis indicated rapid absorption of parent chlorpyrifos from water into blood and slower distribution to peripheral tissues. Total 14C residue concentrations were highest in fat and lowest in muscle. Parent chlorpyrifos comprised &gt; 90% of the total 14C residues in the whole fish. 14C residues were excreted by renal and biliary routes as metabolites of chlorpyrifos; excretion of the parent chemical was negligible. Trichloropyridinol (TCP) was the major metabolite in blood (approximately 40% of total residues), whereas the glucuronide conjugate of TCP was the major metabolite in urine (60–90%) and bile (&gt; 90%). The pharmacokinetics and metabolism of water-borne chlorpyrifos in the channel catfish were similar to the disposition of chlorpyrifos in other vertebrates.
Comparison of two freshwater turtle species as monitors of radionuclide and chemical contamination: DNA Damage and residue analysis
Authors: Meyers-Schöne Linda , Shugart Lee R. , Walton Barbara T. , Beauchamp John J. 
Published: March 2010

Abstract
Two species of turtles that occupy different ecological niches were compared for their usefulness as monitors of freshwater ecosystems where both low-level radioactive and nonradioactive contaminants are present. The pond slider (Trachemys scripta) and common snapping turtle (Chelydra serpentina) were analyzed for the presence of 90Sr, 137Cs, 60Co, and Hg, radionuclides and chemicals known to be present at the contaminated site, and single-strand breaks in liver DNA. The integrity of the DNA was examined by the alkaline unwinding assay, a technique that detects strand breaks as a biological marker of possible exposure to genotoxic agents. This measure of DNA damage was significantly increased in both species of turtles at the contaminated site compared with turtles of the same species at a reference site, and shows that contaminant-exposed populations were under more severe genotoxic stress than those at the reference site. The level of strand breaks observed at the contaminated site was high and in the range reported for other aquatic species exposed to deleterious concentrations of genotoxic agents such as chemicals and ionizing radiation. Statistically significantly higher concentrations of radionuclides and Hg were detected in the turtles from the contaminated area. Mercury concentrations were significantly higher in the more carnivorous snapping turtle compared with the slider; however, both species were effective monitors of the contaminants.
Bioaccumulation of heavy metals by benthic invertebrates at the arkansas river, colorado
Authors: Kiffney Peter M. , Clements William H. 
Published: March 2010

Abstract
A one-year biomonitoring study was conducted to determine the extent of metal contamination (Cd, Cu, and Zn) in a benthic community from the Arkansas River (CO), a subalpine stream impacted by discharges from historic mining operations. Elevated concentrations of metals in water were paralleled by higher concentrations in benthic organisms. Significant differences (p &lt; 0.05) in metal concentrations in aufwuchs and benthic macroinvertebrates among upstream (reference) and downstream (impacted) stations were observed. Metal concentrations in aufwuchs and benthic invertebrates remained elevated at some downstream stations, despite decreases in water concentrations. Time of year and functional group contributed to the variation in metal bioaccumulation in benthic macroinvertebrates. Monitoring metal concentrations in aquatic macroinvertebrates was a better indicator of metal bioavailability in the Arkansas River than ambient (water) metal concentrations.
Comparative analysis of variables to measure recovery rates in streams
Authors: Niemi Gerald J. , Detenbeck Naomi E. , Perry James A. 
Published: March 2010

Abstract
We assessed a series of chemical and biological variables for their abilities and cost effectiveness in determining recovery rates in streams. Using data gathered at the experimental streams of the Monticello Ecological Research Station, several water-quality variables (DO, pH, nutrients), macroinvertebrate densities, macrophyte biomass, and periphyton biomass, and several ecosystem-level variables (e.g., primary production) were compiled and analyzed. Water-quality variables were relatively inexpensive to measure, and many would be relatively easily collected for assessing recovery rates; however, their overall explanatory power for determining recovery of streams, especially biological phenomena, was limited. Several biological variables, including gross primary production, respiration, leaf litter decomposition rates, macroinvertebrate richness, and Collembola density, could be measured reasonably well and required relatively small sample sizes (n &lt; 10) for detecting recovery rates. However, collection of most of these variables was more costly than collection of chemical water-quality variables. The ultimate determination of which variables to measure in assessing recovery in a given ecosystem will need to be based on the disturbances being examined, the importance of the variables to stream health, and the available monetary resources. Generally, comprehensive analyses of recovery rates for a variety of aquatic systems will greatly increase our ability to develop a framework for predicting recovery rates and ultimately improving the quality of the environment.
Geochronology of priority pollutants in a sedimentation area of the rhine river
Authors: Beurskens Jacobus E. M. , Mol Ge A. J. , Barreveld Hein L. , van Munster Bert , Winkels Herman J. 
Published: March 2010

Abstract
Eight sediment cores were taken from Lake Ketelmeer, a sedimentation area of the Rhine River, located in the central part of The Netherlands. Priority pollutants (eight metals, six planar and mono-ortho polychlorinated biphenyls, seven polychlorinated dibenzo-p-dioxins, 10 polychlo-rinated dibenzofurans, and eight polycyclic aromatic hydrocarbons) were determined in all or in a selected number of cores. Present-day and historical levels of pollutants since the late 1930s were established through the use of radionuclide time tracers (137Cs, 134Cs) and area-specific geological time markers. Postdepositional redistribution of pollutants and possible transformations were evaluated by analyzing sediment top-layer samples that were taken in 1972. Disappearance in the anaerobic sediment was observed for several chlorinated biphenyls, dioxins, and furans, Disappearance of the chlorinated compounds may be caused by microbial dechlorination reactions in the anaerobic lake sediment. For the persistent metals and polycyclic aromatic hydrocarbons, as well as for the somewhat changed concentrations of chlorinated aromatics, trends in the concentration profiles during the last five decades are described. Rather low concentrations of almost all studied chlorinated compounds were observed in the early 1940s. These low levels were in contrast to the metal and PAH concentrations, which were already high in the late 1930s and were lowered during the second world war. For all studied compounds, maximum concentrations were found between 1955 and 1975. Cadmium and nickel levels remained high until 1980. The highly toxic 2,3,7,8-tetrachlo-rodibenzo-p-dioxin reached concentrations up to 400 ng/kg in the mid-1960s. Recently deposited sediments showed lower pollutant levels. The levels of lead, arsenic, and all studied PAHs were the lowest observed in the past five decades.
Polychlorinated dibenzo-P-dioxin and dibenzofuran residues in estuarine and coastal north sea sediments: Sources and distribution
Authors: Evers Erik H. G. , Klamer Hans J. C. , Laane Remi W. P. M. , Govers Harrie A. J. 
Published: March 2010

Abstract
Sediments from two depositional zones of the North Sea (the Wadden Sea and Oyster Grounds) and from the estuaries of the rivers Rhine, Meuse, Scheldt, Ems, and Humber were analyzed for polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs) using a congener-specific procedure. A simple grain-size correction procedure was utilized for the comparison of PCDF and PCDD concentrations in sediments from different origin. This procedure, which applies wet sieving of fresh sediment and isolating and analyzing the &lt;63-μm grain-size fraction, was found to be appropriate for comparing levels of PCDFs and PCDDs in different estuarine and coastal sediments. PCDFs were more widely encountered than PCDDs in all sediments, except for the Ems-Dollard and the Humber estuary. The highest concentrations were found in the outflow sediments of the rivers Rhine and Humber. Concentrations up to 2,980 ng/kg PCDFs, principally 1,2,3,4,6,7,8-HpCDF and OCDF, and up to 1,760 ng/kg PCDDs, principally OCDD, were determined in the River Rhine sediments. Principal component analysis was used to visualize the compositional changes of PCDD and PCDF profiles in the sediments. Two-dimensional projections based on sample scores from the principal component models showed a marked influence of the River Rhine on the presence of these compounds in the western Wadden Sea and the Oyster Grounds. Based on a chemo-metric evaluation of chromatographic profiles of these coastal, estuarine and related freshwater sediments, we have deduced that these compounds originate primarily from industrial operation discharges, related to the production of chloroaliphatic compounds and the chloralkali industry along the River Rhine. The atmospheric deposition of combustion-generated PCDDs and PCDFs appeared significant only for remote marine environments.