bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting toxicity in marine sediments with numerical sediment quality guidelines
Authors: Long Edward R , Field L Jay , MacDonald Donald D 
Published: March 2010

AbstractMatching synoptically collected chemical and laboratory bioassay data (n = 1,068) were compiled from analyses of surficial sediment samples collected during 1990 to 1993 to evaluate the predictive ability of sediment quality guidelines (SQGs), specifically, effects range—low (ERL), effects range—median (ERM), threshold effects level (TEL), and probable effects level (PEL) values. Data were acquired from surveys of sediment quality performed in estuaries along the Atlantic, Pacific, and Gulf of Mexico coasts. Samples were classified as either nontoxic (p &gt; 0.05 relative to controls), marginally toxic (p &lt; 0.05 only), or highly toxic (p &lt; 0.05 and response greater than minimum significant difference relative to controls). This analysis indicated that, when not exceeded, the ERLs and TELs were highly predictive of nontoxicity. The percentages of samples that were highly toxic generally increased with increasing numbers of guidelines (particularly the ERMs and PELs) that were exceeded. Also, the incidence of toxicity increased with increases in concentrations of mixtures of chemicals normalized to (divided by) the SQGs. The ERMs and PELs indicated high predictive ability in samples in which many substances exceeded these concentrations. Suggestions are provided on the uses of these estimates of the predictive ability of sediment guidelines.
Comparative developmental toxicity of planar polychlorinated biphenyl congeners in chickens, American kestrels, and common terns
Authors: Hoffman David J , Melancon Mark J , Klein Patrice N , Eisemann John D , Spann James W 
Published: March 2010

Abstract
The effects of polychlorinated biphenyl (PCB) congeners, PCB 126 (3,3′,4,4′,5-pentaCB) and PCB 77 (3,3′4,4′-tetraCB), were examined in chicken (Gallus gallus), American kestrel (Falco sparverius), and common tern (Sterna hirundo) embryos through hatching, following air cell injections on day 4. PCB 126 caused malformations and edema in chickens starting at 0.3 ppb, in kestrels at 2.3 to 23 ppb, but in terns only at levels affecting hatching success (44 ppb). Extent of edema was most severe in chickens and least in terns. Defects of the beak were common in all species but with crossed beak most prevalent in terns. Effects on embryo growth were most apparent for PCB 126 in chickens and kestrels. The approximate 50% lethal dose (LD50) for PCB 126 in chickens was 0.4 ppb, in kestrels was 65 ppb, and in terns was 104 ppb. The approximate LD50 for PCB 77 in chickens was 2.6 ppb and in kestrels was 316 ppb. Induction of cytochrome P450 associated monooxygenase activity (ethoxyresorufin-O-dealkylase activity) by PCB 126 in chick embryo liver was about 800 times more responsive than in tern and at least 1,000 times more responsive than in kestrel. High concentrations of PCB 126 found in bald eagle eggs are nearly 20-fold higher than the lowest toxic concentration tested in kestrels. Concentrations of PCB 126 causing low-level toxic effects in common tern eggs are comparable to highest levels in common terns and Forster's terns in the field, suggesting additional involvement of other compounds in the Great Lakes.
Effect of pH on the toxicity and biodegradation of pentachlorophenol by Sphingomonas sp strain P5 in nutristat culture
Authors: Rutgers Michiel , van Bommel Sander , Breure Anton M , van Andel Johan G , Duetz Wouter A 
Published: March 2010

Abstract
A polychlorinated-phenol degrading bacterium, Sphingomonas sp. strain P5, was grown in nutristat culture (i.e., a continuous culture at a controlled substrate concentration) with pentachlorophenol (PCP) as the sole carbon and energy source. During steady state conditions, the effect of the medium pH on the growth of strain P5 on PCP was established. At lower pH values PCP exhibited a stronger toxicity than at higher pH values. Inhibition of the growth of strain P5 by PCP was correlated to the concentration of the undissociated phenol in the system, rather than to the dissociated or total PCP concentration. The results indicate that acidification of natural environments may enhance the toxicity of chlorophenols and suggest that treatments to increase environmental pH may reduce risk of chlorophenol toxicity at acidified sites.
Photolytic and microbial degradation of 3,5,6-trichloro-2-pyridinol
Authors: Feng Yucheng , Minard Robert D , Bollag Jean-Marc 
Published: March 2010

Abstract
The photolytic and microbial degradation of 3,5,6-trichloro-2-pyridinol (TCP), a metabolite of the insecticide chlorpyrifos and the herbicide triclopyr, has been investigated. TCP (80 mg/L) was decomposed to nondetectable levels within 2 h of ultraviolet irradiation. Release of 14CO2 and chloride ion was observed; however, approximately 60% of the initial radioactivity remained in the solution. Dichlorodihydroxypyridine isomers and reductive dechlorination products were found as intermediate products of TCP photolysis. It was proposed that both hydrolytic and reductive dechlorination occurred during photodegradation of TCP. Although TCP can be degraded via photolysis, many degradation products remained in the aqueous medium and only some of them, the reductive dechlorination products, can be mineralized by Pseudomonas sp. ATCC 700113. The degradation of the parent compound, TCP, by Pseudomonas sp. ATCC 700113 also appears to involve a reductive dechlorination mechanism. A consortium of microorganisms may be needed if a treatment process combining microbial and photolytic activity is to be used to remove TCP in industrial wastewater.
In vitro digestive fluid extraction as a measure of the bioavailability of sediment-associated polycyclic aromatic hydrocarbons: Sources of variation and implications for partitioning models
Authors: Weston Donald P , Mayer Lawrence M 
Published: March 2010

AbstractIn vitro extraction of contaminated sediments using the digestive fluid of a deposit-feeding polychaete has recently been proposed to study contaminant bioaccumulation mechanisms and perhaps to better quantify the bioavailable contaminant fraction. This approach was evaluated using digestive fluid from the polychaete Arenicola brasiliensis and six marine sediments containing both spiked radiolabeled polycyclic aromatic hydrocarbons (PAHs) and in situ–contaminated unlabeled PAHs. The proportion of total contaminant extracted by digestive fluid from each sediment varied from 22 to 71% and 13 to 52%, for phenanthrene and benzo[a]pyrene, respectively. The proportions of contaminant solubilized were inversely correlated with the sediments' organic carbon content. The extent of PAH solubilization among sediments by A. brasiliensis digestive fluid was highly correlated with that of digestive fluid from the echiuran Urechis caupo and appears to be a consequence of surfactant properties of the fluids rather than of their enzymatic activity. The proportion of PAHs solubilized in vitro was similar to in vivo measurements of solubilization for contaminant exposures lasting about 24 h. However, with continued exposure, in vivo PAH concentrations in the digestive fluid increased fivefold, suggesting that digestive fluid is retained in the gut longer than sediment and thus accumulates PAHs through sequential digestion of many gut volumes. This phenomenon may enhance contaminant fugacity in the gut and increase the potential for bioaccumulation or toxicity.
Accumulation of dietary methylmercury in the testes of the adult Brown Norway rat: Impaired testicular and epididymal function
Authors: Friedmann Andrew S , Chen Haolin , Rabuck Lorrine D , Zirkin Barry R 
Published: March 2010

Abstract
The widespread consumption of fish containing elevated concentrations of methylmercury has prompted concern over the health effects of such a diet. Previous studies with rodents have indicated that exposure to dietary mercury (Hg) impairs male reproductive health. However, adverse effects were observed following doses in the range of milligrams per kilogram of body weight, whereas typical human consumption in the United States is in the range of micrograms per kilogram of body weight. This study examined the effects of dietary Hg on male rats using levels of the metal that are more similar to those typically consumed by humans. For 19 weeks, adult male Brown Norway rats were administered methylmercury twice weekly at 0.8, 8.0, or 80 μg/kg. Intratesticular testosterone levels in the high-dose group were reduced by 44%, suggesting that steroidogenesis in these animals was dramatically impaired. Although sperm production was not significantly affected, numbers of sperm in the cauda epididymides of the high-dose group were reduced by 17%. Furthermore, there was a negative correlation between fertility and testicular Hg content. These results raise the possibility that exposure to Hg at levels consumed by humans may result in steroidogenic impairment, reduced sperm counts, and fertility problems.
Sediment quality thresholds: Estimates from hockey stick regression of liver lesion prevalence in english sole (Pleuronectes vetulus)
Authors: Horness Beth H , Lomax Daniel P , Johnson Lyndal L , Myers Mark S , Pierce Susan M , Collier Tracy K 
Published: March 2010

AbstractComprehensive, integrative assessments of coastal sediment quality are best effected by using large, diverse data sets that include measures of biological dysfunction observed in association with chronic exposure to sediment contaminants. Under the auspices of the National Oceanic and Atmospheric Administration's National Status and Trends Program, the National Benthic Surveillance Project accumulated a database of synoptic sediment contaminant concentrations and indices of biological effects that were measured in indigenous animals collected during field surveys conducted from 1984 to 1994. This compilation of data provided the opportunity to develop a new approach for determining sediment quality criteria to add to the current repertoire of environmental assessment tools. Using a two-segment hockey stick regression, statistically significant chemical thresholds of biological effects were estimated for hepatic lesion prevalences in English sole (Pleuronectes vetulus, formerly Parophrys vetulus) in relation to sediment concentrations of polycyclic aromatic hydrocarbons. These threshold estimates are notably lower than many of those reported for other techniques. Application of this relatively simple dose-response model to subacute, chronic effects that are involved in hepatocarcinogenesis and associated with sediment toxicant content (1) reflects the link between toxicopathic disease progression and conditions observed in benthic fish exposed to contaminants and (2) provides endpoints for assessing sediment quality contaminant concentrations that are not necessarily acutely fatal but may have long-term health implications for populations that are chronically exposed.
Chemical stress and metabolic rate in aquatic invertebrates: Threshold, dose–response relationships, and mode of toxic action
Authors: Penttinen Olli-Pekka , Kukkonen Jussi 
Published: March 2010

Abstract
Four aromatic compounds were evaluated in laboratory studies to investigate their accumulation and toxicant-induced changes in the rate of heat dissipation in the freshwater invertebrates Chironomus riparius and Lumbriculus variegatus. The sublethal energetic response detected by direct calorimetry was related to tissue chemical concentration by the threshold model and an attempt was made to apply the critical body residue (CBR) concept. Below the compound-specific tissue threshold concentration or CBR, no correlations were found between the dose and the metabolic rate, and the slopes of the regression were close to zero. Above the threshold, depending on the chemical, metabolic rate either increased or decreased. An increase in heat output produced by 2,4-dinitrophenol (2,4-DNP), pentachlorophenol (PCP), and 2,4,5-trichlorophenol (2,4,5-TCP) was closely correlated with the dose. The order of toxicity for these phenols was 2,4-DNP = PCP &gt; 2,4,5-TCP, which reflects the interaction of compounds' lipophilicities and acidities and their combined influence on bioaccumulation and effects on the energy-transducing membrane by uncoupling oxidative phosphorylation. A decrease in the heat output caused by 1,2,4-trichlorobenzene (1,2,4-TCB) was more variable relative to dose. Also, 1,2,4-TCB required a much higher molar tissue threshold concentration (∼2.0 μmol/g wet weight) than required by phenols to generate the response. Both the metabolic response and the chemical threshold value were those expected to result from narcosis. Results suggest that calorimetric measures can identify not only the integrated physiologic response but also have some resolution of the mechanism of toxic effects.
Decreased transpiration in poplar trees exposed to 2,4,6-trinitrotoluene
Authors: Thompson Phillip L , Ramer Liz A , Guffey Aaron P , Schnoor Jerald L 
Published: March 2010

Abstract
This article discusses the effects of various concentrations of the explosive 2,4,6-trinitrotoluene (TNT) on the transpiration of hybrid poplar trees growing in hydroponic media. Transpiration was measured daily by gravimetric means. The rapid removal of TNT from hydroponic solutions was a result of plant uptake and required a daily dosage of TNT to ensure a relatively constant exposure over time. Transpiration decreased with increasing TNT concentrations ≥5 mg/L. Decreases in transpiration were accompanied by leaf chlorosis and abscission. A comparison between a laboratory study and a pilot-scale experiment showed good scale-up potential.
Zooplankton population and community responses to the pesticide azinphos-methyl in freshwater littoral enclosures
Authors: Sierszen Michael E , Lozano Stephen J 
Published: March 2010

Abstract
We tested the effects of four concentrations (0.2, 1.0, 4.0, and 20.0 μg/L) of the organophosphorus insecticide azinphosmethyl on natural zooplankton communities using littoral ecosystem enclosures. Individual taxa and major zooplankton groups (cladocerans, copepods, and rotifers) exhibited concentration-dependent responses, with most of the significant effects at the two highest concentrations. Analyses of population abundance were more sensitive to the effects of azinphos-methyl than were analyses of major zooplankton groups. Principal component analysis of communities differentiated the contributions of cladocerans, copepods, and rotifers to total community variance. The highest principal components were associated with cladocerans, the group also identified by univariate statistics to be most sensitive to azinphos-methyl. Ordination using the first two principal components depicted the multivariate status of the zooplankton communities through time and showed concentration-dependent effects and recovery from the pesticide at the community level. Principal component ordination was a more sensitive metric of community-level effects than was taxon richness. Communities in the highest treatment concentration had not fully recovered by the last sampling date, 78 d after treatment.
Biochemical and histological responses in rainbow trout (Oncorhynchus mykiss) exposed to 2,3,4,7,8-pentachlorodibenzofuran
Authors: Brown, Scott B , Delorme Peter D , Evans Robert E , Lockhart W Lyle , Muir Derek C.G , Ward Fred J 
Published: March 2010

AbstractRainbow tout were given an intraperitoneal injection of corn oil containing 0 or 8.8 nmol (3 μg) [14C]2,3,4,7,8-pentachlorodibenzofuran (P5CDF)/kg and were then held on a light cycle that induced spawning 10 months later. At 5- to 6-week intervals, blood samples were collected to monitor plasma levels of 17β-estradiol (E2), testosterone (T), thyroxine (T4), 3,5,3′-triiodo-L-thyronine (T3), and calcium; packed cell volume (PCV); and differential blood cell counts. Fish were sacrificed after spawning to examine tissue P5CDF concentration, liver ethoxyresorufin-O-deethylase (EROD), liver vitamins (retinoids and tocopherol), histology (liver, thyroid), and growth parameters. The P5CDF injections produced tissue 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent concentrations comparable to those reported in salmonids from contaminated areas. Highest P5CDF concentrations occurred in gut and liver, but muscle accounted for the greatest proportion of the dose. Plasma hormone and calcium concentrations followed predicted seasonal patterns in both control and exposed fish. PCV was unchanged by repeated blood sampling but differential blood cell counts showed adaptive responses to blood removal. The P5CDF exposure caused transient reductions in circulating lymphocytes and elevated EROD. Additionally, P5CDF increased liver size and depleted retinoid stores in male fish. Liver histology, somatic growth, and gonadal development were unaltered by P5CDF during the first reproductive cycle after exposure.
Effects of organism allocation on toxicity test results
Authors: Davis Robert B , Bailer A John , Oris James T 
Published: March 2010

Abstract
The purpose of this study was to investigate the effect of nonrandom allocation of organisms to treatments in aquatic toxicity tests on lethal concentration estimates. Random allocation of organisms is prescribed to avoid the introduction of systematic bias in these tests; however, completely random assignment is usually impractical. A source of systematic bias in a nonrandom allocation scheme is the potential inverse relationship between organism hardiness and the order in which organisms are captured for assigning to treatment (i.e., less hardy and hence more sensitive individuals are captured first). A Monte Carlo simulation experiment was performed to examine such an inverse relationship for a variety of random allocation schemes, focusing on the mortality endpoint in the fathead minnow larval survival and growth toxicity test. Results of the computer simulation experiment indicated that nonrandom allocation of organisms can produce significant bias in estimates of lethal concentration values. Any attempt at randomization resulted in approximately unbiased estimates of lethal concentration values; however, variance of the estimates increased as allocation schemes deviated from the completely random allocation. This study illustrates the importance of proper training of laboratory personnel to implement some form of random organism allocation. Furthermore, many partial random allocation schemes (i.e., those allocating more than one organism at a time) may still yield unbiased estimates of potency endpoints.
Polybrominated diphenyl ethers and hexabromocyclododecane in sediment and fish from a Swedish River
Authors: Sellström Ulla , Kierkegaard Amelie , de Wit Cynthia , Jansson Bo 
Published: March 2010

Abstract
Fish and sediments from several places along the Swedish River Viskan, sampled in 1995, were analyzed for polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). The samples were collected up- and downstream from several possible point sources (textile industries) for these compounds. Tetrabromodiphenyl ethers (TeBDEs), pentabromodiphenyl ethers (PeBDEs), and decabromodiphenyl ether (DeBDE [BDE209]) were found in sediment. Tetrabromodiphenyl ethers and PeBDEs were also found in fish. Hexabromocyclododecane was identified in sediment and fish. Large fish to sediment ratios for TeBDE, PeBDEs, and HBCD indicate that these are highly bioavailable, whereas BDE209 seems not to be as bioavailable. The lowest PBDE and HBCD levels were found upstream of the industries and concentrations generally increased progressively further downstream as more industries were passed. This is in agreement with earlier investigations of PBDEs in fish from the same river. Many brominated compounds are photolabile, which can complicate their analysis. Under the conditions used in this investigation it was observed that BDE209 in a solvent that was subject to the clean-up procedure partly decomposed to compounds with shorter retention times, whereas BDE209 seemed to be stable in the sample extracts. Another matrix effect could be observed in the increased sensitivity obtained for some of the investigated compounds in fish and sediment extracts as compared to standard solutions. This effect may obscure analytical results obtained with electron capture mass spectrometric detections.
Influence of growth conditions on the results obtained in algal toxicity tests
Authors: Mayer Philipp , Frickmann Jesper , Christensen Erik R , Nyholm Niels 
Published: March 2010

Abstract
The influence of test conditions on results from algal growth inhibition tests was investigated for the toxicants atrazine, 3,4-dichloroaniline, 3,5-dichlorophenol, and potassium dichromate. Emphasis was put on the following four main factors: light, temperature, nitrogen source, and pH. The green alga Selenastrum capricornutum was grown in batch cultures, and the toxic response was measured as reduction in average growth rate, relative to controls. Multifactor experiments were carried out to investigate the effects of the above four factors as well as the interactions between them: light intensity (44 and 198 μE/m2/s), temperature (16 and 26°C), nitrogen source (NH +4 and NO −3), and pH of the medium (7.5 and 8.6). Within the data set generated, the highest and lowest median effective concentration estimate differed by a factor of 3.8. The sensitivity of the test system to 3,4-dichloroaniline, potassium dichromate, and 3,5-dichlorophenol was less under light limitation than under light saturation. Conversely, with the photosynthetic inhibitor atrazine a reduced sensitivity was found at high light intensity, which, however, was high enough to cause slight photoinhibition. The inhibitory response to the weak organic acid 3,5-dichlorophenol was less at the high than at the low pH level, which stems from the fact that neutral species of ionizable compounds are usually more toxic than charged species. No effect of the nitrogen source on inhibitory responses could be ascertained, and temperature influenced the results only indirectly by interacting with light (the saturation intensity increases with temperature). It is concluded that the light intensity in standardized algal toxicity tests could preferably be increased to achieve light-saturated photosynthesis as this may potentially reduce test result variability.