bluuebunny/crossref_metadata_2025 huggingface dataset:
Chronic effects of silver exposure on ion levels, survival, and silver distribution within developing rainbow trout (Oncorhynchus mykiss) embryos
Authors: Guadagnolo Christine M , Brauner Colin J , Wood Chris M
Published: March 2010

Rainbow trout embryos were chronically exposed to silver (as AgNO3) in moderately hard water (120 mg CaCO3/L, 0.70 mM Cl−, 1.3 mg/L dissolved organic matter, 12.3 ± 0.1 °C) at nominal concentrations of 0.1, 1, and 10 μg/L (measured = 0.117 ± 0.008, 1.22 ± 0.16, and 13.51 ± 1.58 μg/L, respectively) to investigate the effects on mortality, ionoregulation, and silver uptake and distribution of the embryo. Mortalities in the low concentrations (0.1 and 1.2 μg/L) were not significantly different from controls throughout embryonic development (days 1–32 postfertilization). Mortalities of embryos in the 13.5-μg/L treatment reached 56% by day 32 postfertilization (33% when accounting for control mortality), by which time more than 50% of surviving embryos had hatched. Accumulation of silver in whole embryos of 1.2- and 13.5-μg/L treatments reached the highest concentrations of 0.13 and 0.24 μg/g total silver, respectively, by day 32, but whole embryo silver burden was not correlated with mortality. Silver concentrations in different compartments of the whole embryo (chorion, dissected embryo, and yolk) were greatest just before hatch and were higher in the chorion for all experimental treatments. Up to 85% of total whole embryo silver content was bound to the chorion, which acts as a protective barrier during silver exposure. Whole embryo Na+ concentration in the 13.5-μg/L treatment was significantly reduced relative to controls from days 23 to 32 postfertilization, and levels in the embryo were reduced by 40% at day 32 postfertilization, indicating that silver toxicity in the whole embryo is associated with an ion regulatory disturbance that is similar to the acute effect of AgNO3 in juvenile and adult trout.
A simple Tenax® extraction method to determine the availability of sediment-sorbed organic compounds
Authors: Cornelissen Gerard , Rigterink Henk , ten Hulscher Dorien E M , Vrind Bea A , van Noort Paul C M
Published: March 2010

A simple method to determine the availability of sediment-sorbed organic contaminants was developed and validated. For 10 polycyclic aromatic hydrocarbons, 4 polychlorinated biphenyls, and 9 chlorobenzenes in 6 sediments, we measured the fraction extracted by Tenax® in 6 and 30 h. These fractions were compared with the rapidly desorbing fractions determined by consecutive Tenax extraction. Extraction by Tenax for 30 h completely removed the rapidly desorbing fraction plus some part of the slowly desorbing fraction. The fraction removed after 30 h was about 1.4 times the rapidly desorbing fraction. The fraction extracted by Tenax after 6 h is about 0.5 times the rapidly desorbing fraction for chlorobenzenes (CBs)/polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). The rapidly desorbing fraction probably represents the fraction of sorbed organic compound that poses actual risks for transport to (ground) water and determines the uptake by organisms and that can be microbially degraded. Extraction by Tenax for 6 h provides an easy way to address these issues more accurately than does the measurement of total concentrations.
Effect of mercury andGpi-2genotype on standard metabolic rate of eastern mosquitofish (Gambusia holbrooki)
Authors: Tatara, Christopher Paul , Newman Michael C , Mulvey Margaret
Published: March 2010

Previous studies demonstrated differential mortality among mosquitofish of different Gpi-2 genotypes during acute mercury and arsenate exposures. Mercury-exposed mosquitofish also had Gpi-2 genotype-specific differences in glycolytic and Krebs cycle metabolite pools. The mortality and metabolite data suggested that mosquitofish bearing specific Gpi-2 genotypes might differ in metabolic efficiency, with less efficient Gpi-2 genotypes having higher standard metabolic rates (SMRs) and shorter times to death during acute mercury exposure. Effect of Gpi-2 genotype on SMR was assessed with a factorial arrangement of six Gpi-2 genotypes and two exposure sequences (Control — Control; Control — 100 μg/L Hg). The SMRs were estimated by measuring oxygen consumption using an indirect, closed-circuit, computer-controlled respirometer. A 48-h exposure to 100 μg/L of mercury resulted in a 16.7% elevation of SMR above control levels (p = 0.001). The Gpi-2 genotype and the number of heterozygous loci per individual had no significant effect on SMR in mercury-exposed mosquitofish. The experimental results do not support the hypothesis that Gpi-2 genotype-specific differences in glycolytic and Krebs cycle metabolite pools and mortality in mosquitofish exposed to mercury are associated with differences in SMR.
Assessment of chloroaniline toxicity by the submitochondrial particle assay
Authors: Argese Emanuele , Bettiol Cinzia , Agnoli Francesca , Zambon Alfonso , Mazzola Martina , Ghirardini Annamaria Volpi
Published: March 2010

The effects on mitochondrial respiration of 15 chloroanilines were recorded by using the in vitro response of submi-tochondrial particles (SMP) from beef heart mitochondria. The bioassay procedure for SMP is based on the process of reverse electron transfer, which can be negatively affected by inhibitors of electron transport, by uncouplers, and by chemicals that impair membrane integrity. The EC50 values, determined for the tested chloroanilines, indicate a general tendency of increasing toxicity with increasing chlorine substitution. In order to validate the results obtained and to evaluate the capability of the SMP assay to reproduce the toxic effects of the examined compounds on different freshwater species, the EC50 values were compared with literature data from other biological assays regarding both in vitro systems and whole organisms. A good correlation was found in particular with two widely used testing systems, the Microtox® and the ##Tetrahymena# assays. In addition, quantitative structure-activity relationships (QSARs) were established between the EC50 values and various molecular descriptors for hydrophobic, steric, and electronic interactions. The results obtained were utilized to elucidate the mechanism of toxic action of chloroanilines, which are commonly reported to act by the polar narcosis mode of action. Moreover, they confirmed that the SMP assay can be a useful tool for studying the toxicity of chemicals that act nonspecifically by impairing membrane structure and functions.
Reevaluating the free-ion activity model of trace metal toxicity toward higher plants: Experimental evidence with copper and zinc
Authors: Parker David R , Pedler Judith F , Ahnstrom Zoe Ann S. , Resketo Margaret
Published: March 2010

Acrossa diverse spectrum of organisms, the absorption and toxicity of trace elements are usually correlated with the activity of the free metal ion, but reported exceptions to this generalization are increasing. For the first time, we tested the validity of the free-ion activity model (FIAM) in the case of terrestrial plants and organic acids that may be abundant in the soil solution and rhizosphere. Short-term (48-h) root elongation of wheat (Triticum aestivum L.) in a simple medium (2 mM CaCl2, pH 6.0) was used to probe the toxicity of Cu and Zn in the presence of malonate, malate, and citrate. Precautions were taken to prevent biodegradation of the organic acids, and its absence was confirmed by ion chromatography. Copper speciation was verified using a Cu-selective ion electrode, and published stability constants were modified to improve agreement between measured and calculated Cu2+ activities. With additions of both malonate and malate, Cu toxicity was alleviated but not to the extent predicted by the FIAM; the Cu-ligand complexes seemingly contributed to the toxicity. No such departures were observed with citrate and Cu nor with any of the three ligands in combination with Zn. Thus, exceptions to the FIAM occur with higher plants as well as with aquatic biota but do not seem to occur in a predictable or systematic fashion with respect to metal or organic acid under investigation. Several possible explanations for the observed departures from the FIAM are discussed, including the possibility of accidental cotransport of metal and ligand into the cytoplasm.
Effects of copper on olfaction of colorado pikeminnow
Authors: Beyers Daniel W , Farmer Michael S
Published: March 2010

Effects of copper on olfaction of Colorado pikeminnow (Ptychocheilus lucius) were investigated by exposing fish for 24 or 96 h, then evaluating olfactory ability using a behavioral assay and observing olfactory structures using scanning electron microscopy (SEM). The behavioral assay measured a response known as fright reaction. Failure of exposed fish to demonstrate a fright reaction in the presence of skin homogenate assumed to contain fright pheromone was considered evidence of copper-induced loss of olfactory ability. Regression analysis was used to describe the response of fish as a function of copper concentration at each exposure duration. Olfactory ability declined with increasing copper concentration. For copper concentrations less than 66 μg/L, olfaction was more sensitive to exposure at 24 h than at 96 h. This result suggests that physiological adaptation and recovery of sensory ability occurred despite continuous exposure in the 96-h treatment. Protective mechanisms induced by exposure may have reduced sensitivity to copper by 96 h. Systematic surveys using SEM to detect presence or absence of olfactory receptors confirmed results of behavioral assays. Copper concentrations in one river inhabited by Colorado pikeminnow were compared with effective concentrations estimated by regression. Comparisons suggest that ambient copper concentrations may occasionally inhibit olfaction of wild fish.
Human toxicity potentials for life-cycle assessment and toxics release inventory risk screening
Authors: Hertwich Edgar G , Mateles Sarah F , Pease William S , McKone Thomas E
Published: March 2010

The human toxicity potential (HTP), a calculated index that reflects the potential harm of a unit of chemical released into the environment, is based on both the inherent toxicity of a compound and its potential dose. It is used to weight emissions inventoried as part of a life-cycle assessment (LCA) or in the toxics release inventory (TRI) and to aggregate emissions in terms of a reference compound. Total emissions can be evaluated in terms of benzene equivalence (carcinogens) and toluene equivalents (noncarcinogens). The potential dose is calculated using a generic fate and exposure model, CalTOX, which determines the distribution of a chemical in a model environment and accounts for a number of exposure routes, including inhalation, ingestion of produce, fish, and meat, and dermal contact with water and soil. Toxicity is represented by the cancer potency q1* for carcinogens and the safe dose (RfD, RfC) for noncarcinogens. This article presents cancer and noncancer HTP values for air and surface-water emissions of 330 compounds. This list covers 258 chemicals listed in U.S. Environmental Protection Agency TRI, or 79 weight-% of the TRI releases to air reported in 1997.
Ecotoxicological effects of hexahydro-1,3,5-trinitro-1,3,5-triazine on soil microbial activities
Authors: Gong Ping , Hawari Jalal , Thiboutot Sonia , Ampleman Guy , Sunahara Geoffrey I
Published: March 2010

Although hexahydro-1,3,5-trinitro-1,3,5-triazine (also called RDX or hexogen) is a potentially toxic explosive compound that persists in soil, its ecotoxicological effects on soil organisms have rarely been assessed. In this study, two uncontaminated garden soils were spiked with 10 to 12,500 mg RDX/kg dry soil. Soil microbial activities, i.e., potential nitrification, nitrogen fixation, dehydrogenase, basal respiration, and substrate-induced respiration were chosen as bioindicators and were determined after 1-, 4-, and 12-weeks of exposure. Experimental results indicate that RDX showed significant inhibition (up to 36% of control) on indigenous soil microbial communities over the period of this study. All five bioindicators responded similarly to the RDX challenge. The length of exposure also affected the microbial toxicity of RDX, with 12-week exposure exerting more significant effects than the shorter exposure periods, suggesting that soil microorganisms might become more vulnerable to RDX when exposure is extended. The estimated lowest observable adverse effect concentration of RDX was 1,235 mg/kg. No biodegradation products of RDX were detected at all three sampling times. Compared with 2,4,6-trinitrotoluene (TNT), RDX is less toxic to microbes, probably because of its resistance to biodegradation under aerobic conditions, which precludes metabolic activation of nitro groups.
Effect of bile salts, lipid, and humic acids on absorption of benzo[a]pyrene by isolated channel catfish (Ictalurus punctatus) intestine segments
Authors: Weber Lynn P , Lanno Roman P
Published: March 2010

Dietary absorption of lipophilic contaminants may be a significant route of exposure in aquatic organisms. Bile salts, lipids, and humic acids are important factors that may influence the intestinal absorption of a contaminant such as benzo[a]pyrene (BaP). We hypothesized that bile salts, monoglycerides, and free fatty acids would increase BaP intestinal absorption, while triglycerides, humic acids, and sediment would decrease BaP intestinal absorption. We have established and validated an in vitro model to examine modification of 3H-BaP absorption in everted intestinal segments from channel catfish (Ictalurus punctatus). Uptake of BaP into the everted intestinal segments continued to increase over the times examined in this study (60 min) and apparently occurs passively; thus, fugacity-based models of uptake are supported. Absorption of BaP into intestinal cells was significantly decreased by the addition of monoglycerides and free fatty acids to bile salts in the incubation media. Addition of triglycerides decreased BaP absorption even further. Humic acids may have decreased BaP intestinal absorption, while natural sediment may have increased BaP absorption. The results of this study suggest that all lipids may decrease intestinal uptake of lipophilic contaminants if they remain in unabsorbable excess in the intestinal lumen by retaining BaP in lipid/bile micelles. In contrast, if triglycerides are hydrolyzed into monoglycerides/free fatty acids prior to absorption, lipophilic contaminant uptake will likely be facilitated. Thus, it may be the hydrolytic state of lipids that determines its effects on BaP absorption. Humic acids alone may decrease dietary uptake of BaP, but our results suggest that other components in natural sediment may counteract this effect to cause a slight enhancement of BaP uptake. Further studies are needed to determine the dietary conditions necessary for bio-accumulation to contribute significantly to lipophilic contaminant body burdens in benthivorous fish. Finally, the everted intestinal segment technique has the potential to be used in other species and with different contaminants.
Toxicant- and response-specific comparisons of statistical methods for estimating effective concentrations
Authors: Hughes Michael R. , Bailer A John , Denton Debra L
Published: March 2010

Standard U.S. Environmental Protection Agency (U.S. EPA) statistical analyses of whole effluent toxicity tests involve the estimation of the concentration associated with a specified level of inhibition relative to control responses. Current U.S. EPA estimation methods (linear interpolation or probit-based methods) are compared to a recently developed parametric regression-based estimator, the relative inhibition concentration estimator RIp. The RIp estimation technique, with level of inhibition p = 25%, is applied to a series of chronic toxicity test data from a U.S. EPA Region 9 database of reference toxicity tests. Tests on marine species are conducted with one reference toxicant, while the freshwater tests are conducted with several reference toxicants. While the U.S. EPA estimators and the RIp estimator are highly correlated for red abalone larval shell development, the degree of correlation for fathead minnow responses varies with reference toxicant tested. The strength of the relationship between the RIp and the standard U.S. EPA estimators varies as a function of the reference toxicant. Correlations range between 0.67 and 0.99. For all biological responses included in this evaluation (fathead minnow growth or survival and red abalone larval development), experiments occurred where the RIp is estimable, while the standard U.S. EPA estimators are not. Nonestimability of the standard EPA methods appears to be related, in part, to the failure of models to account for enhanced responses, such as a hormesis effect prior to toxicity being manifest. The ability to account for such enhanced responses is a strength of the RIp method. Finally, a variance component analysis suggests that lab-to-lab variability is relatively low for the red abalone but relatively high for the fathead minnow.
Characterization of enzymes involved in biotransformation of polycyclic aromatic hydrocarbons in terrestrial isopods
Authors: de Knecht Joop A , Stroomberg Gerard J , Tump Cornelis , Helms Martine , Verweij Rudo A , Commandeur Jan , van Gestel Cornelis A M , van Straalen Nico M
Published: March 2010

Little is known about the capacity of terrestrial invertebrates to transform organic soil pollutants such as polycyclic aromatic hydrocarbons (PAHs). Studies were designed to characterize microsomal mixed function oxygenase and accompanying conjugation enzymes from the hepatopancreas of the terrestrial isopods Porcellio scaber and Oniscus asellus using pyrene and 1-hydroxypyrene as model substrates. The hydroxylation of pyrene and the formation of pyreneglucoside and pyrenesulfate appeared to be sensitive measures for the activity of cytochrome P450 aryl hydrocarbon hydroxylase (AHH), uridinediphosphateglucosyltransferase (UDPGT), and aryl sulfotransferase (ST), respectively. Treatment with the antibiotic riphampicine demonstrated that the enzyme activities originate from the animals themselves and not from symbiotic microflora present in the hepatopancreas and the gut. In both species, ST has a very high affinity for 1-hydroxypyrene with Km values two orders of magnitude lower than that of UDPGT. The Vmax values of UDPGT, however, are 10- to 20-fold higher than that of ST. Taking the P450 activities into consideration, both species are expected to transform PAHs in an equally effective way. When the isopods were fed with food containing benzo[a]pyrene and 3-methyl-cholanthrene, none of the enzyme activities appeared to be inducible except for a small enhancement of UDPGT in O. asellus. Our findings indicate that terrestrial isopods have a high, noninducible capacity for biotransformation of PAHs and that the sulfate conjugation pathway is as important as the carbohydrate conjugation pathway. This conclusion is consistent with the low body residues of parent PAHs found in the field.
Effects of parathion on acetylcholinesterase, butyrylcholinesterase, and carboxylesterase in three-spined stickleback (Gasterosteus aculeatus) following short-term exposure
Authors: Wogram Jörn , Sturm Armin , Segner Helmut , Liess Matthias
Published: March 2010

The sensitivity of butyrylcholinesterase (BChE) toward the inhibition by the organophosphorus insecticide (OP) parathion-ethyl was compared with that of other esterases in the fish three-spined stickleback. Earlier field and in vitro results had suggested the higher sensitivity to OPs of stickleback BChE when compared with acetylcholinesterase (AChE). In the present study, stickleback were exposed in vivo under environmentally realistic conditions using a short duration of exposure (1 h) and parathion concentrations of 0.01, 0.1, and 1.0 μg/L. Seventy and 80% of nominal concentrations, respectively, were measured in the 0.01 and 0.1 μg/L treatments. Following exposure, stickleback were maintained in clean water for 48 h (recovery), allowing the metabolic activation of parathion. After recovery, the activities of BChE (axial muscle, gills, liver), AChE (brain, axial muscle, gills), and carboxylesterase (CaE, liver) were determined. Following exposure to 1 μg/L parathion, the BChE activity was significantly decreased in liver (∼60%) and axial muscle (∼30%), while its decrease in gills (∼30%) was not significant. No effects on BChE activity were observed with 0.1 and 0.01 μg/L parathion. The AChE and CaE activities remained unaffected with all parathion concentrations used. The results are discussed with respect to the potential application of stickleback BChE as a biomarker of OP exposure.
The relationship of Chironomus riparius larval Se body burden and body concentration to larval dry mass and effects on sensitivity to selenium
Authors: Beaty T. Vernon , Hendricks Albert C
Published: March 2010

Selenium as selenite was added to laboratory cultures of Chironomus riparius. In two sets of cultures, substrate-bound Se concentrations were typically 103 times dissolved Se concentrations, while in the other set dissolved Se concentrations were about 10 to 50 times substrate-bound Se concentrations. Body burdens of individual second-, third-, and fourth-instar larvae and eviscerated fourth-instar larvae were measured. Regressions of Se body burden on larval dry mass found evidence for separate intercepts but common slopes for each instar, and Se body concentrations were diluted by growth. The derivation of body concentration from body burden as a function of larval dry mass was used to derive a model of body burden and body concentration as a function of instar. Toxicity tests were performed to check for a change in sensitivity to Se as a function of culture Se concentration. Larval Se concentrations were highly correlated with dissolved Se concentrations but not with substrate-bound Se concentrations. Increases in Se in substrate caused no sensitization, while increases in dissolved Se caused desensitization. We concluded that covariates such as larval dry mass should be incorporated when deriving water quality criteria.
Determination of microcystins in cyanobacterial blooms by solid-phase microextraction-high-performance liquid chromatography
Authors: Poon Ka-Fai , Lam Michael Hon-wah , Lam Paul K S , Wong Bryan S F
Published: March 2010

A solid-phase microextraction (SPME) method was applied to study microcystin (MC) profiles in a natural Microcystis sp. bloom in a freshwater pond in Guangzhou, China. Three dominant MC variants, namely MC-LR, MC-YR, and MC-RR, were quantified. Simultaneous study of their total, extracellular, and intracellular profiles was made possible using SPME coupled to high-performance liquid chromatography. The total and intracellular concentrations of MC-LR in the bloom were 8.67 × 10−2 μg/ml and 1.93 mg/g, respectively. The corresponding concentrations of MC-YR were 1.20 × 10−3 μg/ml and 0.06 mg/g, respectively, and those of MC-RR were 5.57 × 10−2 μg/ml and 1.49 mg/g, respectively. Only MC-LR was detectable in the extracellular phase (1.49 × 10−2 μg/ml) of the bloom, and its concentration was 14% of the intracellular content. Mass balance consideration revealed that only 71.1% of total MC-LR, 36.0% of total MC-YR, and 67.4% of total MC-RR within the cyanobacterial cells were released into the aqueous phase immediately after cell lysis.
Effects of fungicides on thyroid function, metabolism, and thermoregulation in cotton rats
Authors: Tomasi Thomas E , Ashcraft John , Britzke Eric
Published: March 2010

Among the myriad of recent studies on endocrine-disrupting chemicals, relatively few involve thyroid disruption, and most of these address exposure/disruption during embryonic life. Of those involving adult vertebrates, the endpoints examined are thyroid measurements. Even though thyroid disruption could potentially interfere with energy metabolism and thermoregulation such that over-winter survival might be compromised, the possible energetic consequences of these thyroid perturbations have not been investigated. We assessed thyroid function and measured resting metabolic rates of cotton rats chronically exposed to the fungicides vinclozolin or mancozeb. In addition, we measured norepinephrine-induced nonshivering thermogenesis and cold-induced thermogenesis and then cold-acclimated the mancozeb animals. Although thyroid hormone concentrations generally decreased, this was compensated for by an increase in thyroxine turnover (vinclozolin study only) such that thyroxine utilization rate was not different. In addition, there was no difference between the treated and control animals in any of the metabolic parameters measured. It is concluded that wild rodents exposed to these compounds are not energetically compromised.
Assessing the potential for pesticide leaching for the pine forest areas of Tenerife
Authors: Diaz-Diaz Ricardo , Loague Keith
Published: March 2010

Currently, no guidelines cover use of pesticides in the forested areas of the Canary island of Tenerife. An index-based model (Li) was used to rank the leaching potential of 50 pesticides that are, or could be, used for management purposes in the pine forest areas of Tenerife. Once the pesticides with the greatest leaching potential were identified, regional-scale groundwater vulnerability assessments, with consideration for data uncertainties, were generated using soil, climatic, and chemical information in a geographic information system framework for all pine forest areas of the island. Process-based simulations with the pesticide root zone model for the areas and pesticides of highest vulnerability were conducted to quantitatively characterize the leaching potentials. Carbofuran, hexazinone, picloram, tebuthiuron, and triclopyr were each identified as being potential leachers.
The sheepshead minnow as an in vivo model for endocrine disruption in marine teleosts: A partial life-cycle test with 17α-ethynylestradiol
Authors: Zillioux Edward J , Johnson Isabel C , Kiparissis Yiannis , Metcalfe Chris D , Wheat Jeff V , Ward Scott G , Liu Hui
Published: March 2010

The sheepshead minnow (Cyprinodon variegatus Lacépède), an estuarine fish species, was exposed to 17α-ethynyl-estradiol (EE2) at nominal test concentrations of 0.2, 2, 20, 200, 400, 800, 1,600, and 3,200 ng/L. Fish were exposed for up to 59 d, from subadult stages to sexual maturity, under flow-through conditions. The exposure period was followed by an evaluation of reproductive success and survival of progeny. The reproductive success of exposed sheepshead minnows, as determined from data on egg production from two subsequent spawning trials, was reduced in fish exposed to 200 ng/L EE2 and, in one spawning trial, in the 20-ng/L treatment. Hatching success was reduced in the progeny of fish exposed to 200 ng/L EE2, but survival was good among fry that successfully hatched. Histological examination indicated generalized edema, damage to gill epithelia, hepatic toxicity, fibrosis of the testis, and evidence of sex reversal, including testes–ova and spermatagonia-like cells in ovaries. The maximum acceptable toxicant concentration (MATC) for gonadal development in males was within the normal range of EE2 concentrations in sewage treatment plant effluents. The exposure regimen and choice of test organism, combined with histological examination, allowed independent evaluation of ecologically significant acute, reproductive and estrogenic endpoints. Estrogen receptor–mediated effects occurred at concentrations where reproductive effects were measurable under standard reproduction assays. The sheepshead minnow appears to be a sensitive in vivo model for partial life-cycle testing of compounds that have the potential to disrupt the endocrine system as well as reproduction in estuarine and coastal marine fish species.
Phototoxicity of anthracene and pyrene to glochidia of the freshwater musselUtterbackia imbecillis
Authors: Weinstein John E , Polk Kevin D
Published: March 2010

The acute toxicity of photoactivated anthracene and pyrene to the glochidial larvae of the paper pondshell (Utterbackia imbecillis) was characterized in the laboratory using two sets of experiments. Acute toxicity tests designed to determine the overall sensitivity of glochidia to anthracene and pyrene were conducted under simulated sunlight (ultraviolet [UV]-A = 70 ± 0.5 μW/cm2 [mean ± standard deviation]). The median lethal concentration (LC50) and median lethal dose (LD50) of anthracene at 24 h were 1.93 (95% CI, 0.87–3.02) μg/L and 1.94 (1.87–2.00) μg/g glochidia, respectively. The LC50 and LD50 for pyrene at 24 h were 2.63 (2.38–2.90) μg/L and 6.36 (5.82–6.94) μg/g glochidia, respectively. Acute toxicity tests designed to delineate the relationship between the rate of mortality and UV intensity were conducted under one of four different UV intensities (UV-A = 15, 31, 50, and 68 μW/cm2). Regression analyses revealed that time to death decreased as tissue residue concentrations and UV intensity increased for both compounds. Based on measured tissue residues, anthracene was 1.5-fold more potent than pyrene and 3-fold more potent than fluoranthene. The lower potency of fluoranthene is in agreement with previously developed structure–activity relationships; however, these relationships predict equal potency between anthracene and pyrene. These findings suggest that glochidia of freshwater mussels are sensitive to photoactivated anthracene and pyrene at environmentally relevant concentrations, that the time-dependent mortality of glochidia can be accurately predicted through evaluating the product of tissue residue and light intensity, and that species-dependent factors may alter the predicted relative potencies of anthracene and pyrene.
Vertical distribution profiles of linear alkylbenzene sulfonates and their long-chain intermediate degradation products in coastal marine sediments
Authors: León Victor M , González-Mazo Eduardo , Pajares Jesus M. Forja , Gómez-Parra Abelardo
Published: March 2010

The variation with depth of the concentration of linear alkylbenzene sulfonates (LASs) and of the long-chain sulfophenyl carboxylic acids (SPCs) resulting from LAS biodegradation was determined in coastal sediments. We analyzed samples of sediment cores taken from three locations in a littoral zone subjected to the discharge of untreated urban effluents in the Bay of Cádiz in the southwestern part of the Iberian Peninsula. The vertical profile of LAS concentrations showed a sharp reduction with depth, whereas the concentration of long-chain SPCs (6–13 carbon atoms) was greatest at 10 to 14 cm depth. At this depth, the conditions in the interstitial water are strictly anoxic (Eh = −380 mV). The partition coefficients between the solid phase of the sediment versus the interstitial water are very different for LAS and for its degradation intermediates. For LAS, the organic carbon-based partition coefficient values were between 2.4 × 103 and 6.6 × 1055 L/kg for the C10 and C13 homologues, respectively; these values are similar to those obtained from laboratory tests for the sorption of LAS onto marine sediments. For the long-chain SPCs, the partition coefficients are several orders of magnitude less as a consequence of their lower hydrophobicity.
Toxicity of atrazine to the estuarine phytoplankterPavlovasp. (Prymnesiophyceae): Increased sensitivity after long-term, low-level population exposure
Authors: Pennington Paul L , Scott Geoffrey I
Published: March 2010

Phytoplankton are potentially more at risk to the adverse effects of herbicides than many other organisms in estuarine ecosystems. The focus of this study was to characterize the toxicity of a widely used herbicide, atrazine, to a single species of phytoplankton. The nanoplankter Pavlova sp. was grown under controlled laboratory conditions and was used to elucidate short-term, high-level population effects of atrazine. Secondly, a long-term, multigenerational population exposure was performed with a low level of atrazine followed by an additional short-term, high-level exposure on the same population with no recovery period. The 96–h growth rate of 50% effective concentration (EC50) for Pavlova sp. was 147 μg/L (95% CI = 116.4–178.7 μg/L). Long-term exposure at 20 μg/L for four (batch culture) growth cycles (∼20 generations) had no significant effect on the growth rate of Pavlova sp. except during the fourth growth cycle. However, a subsequent short-term, high-level 96–h exposure inoculated from the long-term, low-level exposed population showed increased sensitivity to atrazine (96–h growth rate EC50 = 96.0 μg/L, 95% CI = 90.2–103.7 μg/L). Multigenerational exposure to atrazine appeared to render phytoplankton significantly more sensitive (35%) to atrazine effects. Given the documented persistence of atrazine in surface waters, long-term exposure to low levels of atrazine without recovery may lead to shifts in species sensitivity and potential alterations in phytoplankton population dynamics.
An evaluation of methods for calculating mean sediment quality guideline quotients as indicators of contamination and acute toxicity to amphipods by chemical mixtures
Authors: Fairey Russell , Long Edward R , Roberts Cassandra A , Anderson Brian S , Phillips Bryn M , Hunt John W , Puckett Howard R , Wilson Craig J
Published: March 2010

Mean sediment quality guideline quotients (mean SQGQs) were developed to represent the presence of chemical mixtures in sediments and are derived by normalizing a suite of chemicals to their respective numerical sediment quality guidelines (SQGs). Mean SQGQs incorporate the number of SQGs exceeded and the degree to which they are exceeded and are used for comparison with observed biological effects in the laboratory or field. The current research makes it clear, however, that the number and type of SQGs used in the derivation of these mean quotients can influence the ability of mean SQGQ values to correctly predict acute toxicity to marine amphipods in laboratory toxicity tests. To determine the optimal predictive ability of mean SQGQs, a total of 18 different chemical combinations were developed and compared. The ability of each set of mean SQGQs to correctly predict the presence and absence of acute toxicity to amphipods was determined using three independent databases (n = 605, 2753, 226). Calculated mean SQGQ values for all chemical combinations ranged from 0.002 to 100. The mean SQGQ that was most predictive of acute toxicity to amphipods is calculated as SQGQ1 = ((γ ([cadmium]/4.21)([copper]/270)([lead]/112.18)([silver]/1.77)([zinc]/410)([total chlordane]/6)([dieldrin]/8)([total PAHoc]/1,800)([total PCB]/400))/9). Both the incidence and magnitude of acute toxicity to amphipods increased with increasing SQGQ1 values. To provide better comparability between regions and national surveys, SQGQ1 is recommended to serve as the standard method for combination of chemicals and respective SQGs when calculating mean SQGQs.
Reproductive toxicity in mink (Mustela vison) chronically exposed to environmentally relevant polychlorinated biphenyl concentrations
Authors: Brunström Björn , Lund Bert-Ove , Bergman Anders , Asplund Lillemor , Athanassiadis Ioannis , Athanasiadou Maria , Jensen Sören , Örberg Jan
Published: March 2010

Female mink were exposed to a technical polychlorinated biphenyl (PCB) preparation (Clophen A50 [A50]; 0.1 or 0.3 mg/animal/d), one fraction of A50 containing the non- and mono-ortho-chlorinated congeners (0–1-ortho-chlorobiphenyls [CBs]), another fraction of A50 containing the congeners with two to four ortho-chlorines (2–4-ortho-CBs), or an organic extract from Baltic gray seal blubber. The animals were exposed for 18 months, including two reproduction seasons. Among the animals given the highest dose of A50, the whelping frequency was reduced in the second reproductive season, and all kits died within 24 h of birth. Reproduction was also impaired by the lower dose of A50. Daily exposure to the 0–1-ortho-CBs separated from 0.3 mg A50 severely reduced kit survival. Reproduction was not significantly impaired by daily exposure to the 2–4-ortho-CBs separated from 0.3 mg A50 or by exposure to the blubber extract. We conclude that the reproductive toxicity in chronically PCB-exposed mink is caused by the aryl hydrocarbon (Ah) receptor agonists. The lowest-observed-effect level for reproductive impairment was 2.4 ng 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TEQs) per kilogram body weight and day (22 pg TEQs/g feed). Ethoxyresorufin-O-dealkylase (EROD) was strongly induced by the 0–1-ortho-CBs and pentoxyresorufin-O-dealkylase by the 2–4-ortho-CBs. High EROD activity was correlated with low kit production, and consequently EROD may serve as a marker for reproductive toxicity by Ah receptor agonists in mink.
Impact of herbicides on the abundance and structure of indigenous β-subgroup ammonia-oxidizer communities in soil microcosms
Authors: Chang Yun-Juan , Hussain A. K. M. Anwar , Stephen John R , Mullen Mike D , White David C , Peacock Aaron
Published: March 2010

In this study, mixtures of five herbicide-formulated products (atrazine, dicamba, fluometuron, metolachlor, and sulfentrazone) were applied to soil microcosm columns in increasing concentrations. The toxic impact of herbicides on the indigenous β-subclass Proteobacteria autotrophic ammonia-oxidizer (β-AAO) community was assessed. The β-AAO population abundances were estimated by competitive polymerase chain reaction (PCR) targeting the gene amoA, encoding the α-subunit of ammonia monooxygenase. Community structure was examined by PCR and denaturing gradient gel electrophoresis targeting 16S rDNA with band excision and sequence analysis, and by analysis of amoA gene fragment clone libraries. The 16S rDNA analyses showed that a single ribotype of Nitrosospira cluster 3 was the dominant β-AAO in all treatments. At a finer scale, amoA clone library analysis suggested a shift in community structure corresponding to the 100-ppm application. Competitive PCR indicated significant differences between treatments. The control exhibited relatively stable population abundance over the time period examined. The 10-ppm treatment induced a population increase, but a significant decrease was induced by the 100-ppm application. At 1,000 ppm, the ammonia-oxidizer population dropped below the method detection limit by the first sampling point. An impact on ammonia oxidizers resulting from the application of herbicides was observed, both in abundance and community structure.
Bioaccumulation and toxicokinetics of 42 polychlorinated biphenyl congeners in American kestrels (Falco sparverius)
Authors: Drouillard Ken G , Fernie Kimberly J , Smits Judit E , Bortolotti Gary R , Bird David M , Norstrom Ross J
Published: March 2010

The bioaccumulation and toxicokinetics of 42 polychlorinated biphenyls (PCBs) was determined in male Amrican kestrels exposed to an Aroclor®-contaminated diet for 120 d followed by a 348-d depuration period. The birds were housed under ambient outdoor temperatures to permit normal fluctuations in body weight during the study. Whole body PCB clearance, plasma/fat distribution coefficients, and plasma PCB clearance constants were determined for individual PCBs to calibrate a two-compartment rate constant model in order to describe PCB elimination in the birds. Plasma/fat partition coefficients (KPF) averaged 0.0060 ± 0.0001 for all congeners of study, were not dependent on chemical hydrophobicity, and did not change in summer versus winter sacrificed animals. Plasma clearance constants (k′pc) for PCBs were observed to be dependent on both chlorine substitution patterns and congener hydrophobicity. Polychlorinated biphenyl congeners categorized as readily cleared congeners contained vicinal meta–para hydrogen substituents on at least one phenyl ring, while slowly cleared congeners were chlorine hindered at these positions. A general equation was derived to predict plasma clearance constants for all tri- to octachlorobiphenyls based on the presence of an open meta–para site on one of the phenyl rings and from the n-octanol–water partition coefficient of the chemical. The equation was validated by comparing predicted versus measured relative biomagnification factors of PCBs determined in birds at the end of the dosing period. The two-compartment model calibrated for PCB elimination in American kestrels may be used to describe PCB toxicokinetics in wild birds provided that seasonal fluctuations in the fat content of the modeled population is known.
Absorption of copper(II) by creosote bush (Larrea tridentata): Use of atomic and x-ray absorption spectroscopy
Authors: Gardea-Torresdey Jorge Luis , Arteaga Socorro , Tiemann Kirk J , Chianelli Russell , Pingitore Nicholas , Mackay William
Published: March 2010

Larrea tridentata (creosote bush), a common North American native desert shrub, exhibits the ability to take up copper(II) ions rapidly from solution. Following hydroponic studies, U.S. Environmental Protection Agency method 200.3 was used to digest the plant samples, and flame atomic absorption spectroscopy (FAAS) was used to determine the amount of copper taken up in different parts of the plant. The amount of copper(II) found within the roots, stems, and leaves was 13.8, 1.1, and 0.6 mg/g, respectively, after the creosote bush was exposed to a 63.5-ppm copper(II) solution for 48 h. When the plant was exposed to a 635-ppm copper(II) solution, the roots, stems, and leaves contained 35.0, 10.5, and 3.8 mg/g, respectively. In addition to FAAS analysis, x-ray microfluorescence (XRMF) analysis of the plant samples provided further confirmation of copper absorption by the various plant parts. X-ray absorption spectroscopy (XAS) elucidated the oxidation state of the copper absorbed by the plants. The copper(II) absorbed from solution remained as copper(II) bound to oxygen-containing ligands within the plant samples. The results of this study indicate that creosote bush may provide a useful and novel method of removing copper(II) from contaminated soils in an environmentally friendly manner.
Effects of polycyclic aromatic compounds on the drought tolerance of Folsomia fimetaria (Collembola, Isotomidae)
Authors: Sjursen Heidi , Sverdrup Line Emilie , Krogh Paul Henning
Published: March 2010

Dought tolerance (survival at 98.2% relative humidity and 20°C) was investigated for adult individuals of the springtail Folsomia fimetaria after three weeks of exposure to different polycyclic aromatic compounds (PACs). Seven PACs were investigated (acridine, dibenzofuran, carbazole, fluorene, dibenzothiophene, fluoranthene, and pyrene), with each substance used at several exposure concentrations. Sublethal concentrations of dibenzothiophene, fluorene, fluoranthene, and pyrene caused a dose-related decrease in drought tolerance in exposed adults, whereas no such relationship was found for acridine, dibenzofuran, and carbazole. The organisms used in the drought tolerance study were taken directly from standard ecotoxicity tests that had just been completed, hence the concentrations causing subsequent effects on drought tolerance and those affecting survival and reproduction in the ecotoxicity tests could be compared. Some of the tested substances significantly reduced the drought tolerance of F. fimetaria at concentrations that had little effect on survival, indicating a synergistic effect of the two stressors. However, drought tolerance was affected at concentrations below the threshold value for toxicity in standard tests (no-observed-effect concentration for reproduction) only for dibenzothiophene. In the field, soil organisms exposed to contaminants also face multiple environmental stressors such as drought and cold. Because the reduced drought tolerance is a side effect of chemical exposure, such effects should be considered when extrapolating from laboratory to field conditions.
Biological measurement of estrogenic activity in urine and bile conjugates with the in vitro ER-CALUX reporter gene assay
Authors: Legler Juliette , Jonas Arjen , Lahr Joost , Vethaak A. Dick , Brouwer Abraham , Murk Albertinka J.
Published: March 2010

Although estrogens are excreted as biologically inactive conjugates, they can be reconverted to an active form, possibly by bacteria. A simple method was developed to deconjugate estrogen metabolites present in human urine and fish bile back to active estrogens by enzymatic hydrolysis with β-glucuronidase or live Escherichia coli cells. Deconjugated extracts were tested for estrogenic activity in the in vitro stable estrogen receptor—mediated chemical-activated luciferase gene expression (ER-CALUX) assay. Estrogen glucuronides in urine obtained from human males and females were effectively converted to active forms after incubation with β-glucuronidase or E. coli. The highest estrogenic activity was found in deconjugated metabolites from urine of a pregnant woman, in which levels up to 3,000 nmol estradiol equivalents per liter of urine were found after overnight incubation of urine with E. coli. Bile sampled from male bream and flounder from various freshwater and marine locations was also deconjugated and a good correlation was found between high biliary estrogenic activity and elevated levels of xenoestrogenic activity in surface water as well as in plasma vitellogenin. Therefore, the measurement of deconjugated bile could form a useful (indirect) biomarker for internal dose of xenoestrogens in male fish.
The potential for estradiol and ethinylestradiol degradation in english rivers
Authors: Jürgens Monika D. , Holthaus Karlijn I. E. , Johnson Andrew C. , Smith Jennifer J. L. , Hetheridge Malcom , Williams Richard J.
Published: March 2010

Water samples were collected in spring, summer, and winter from English rivers in urban/industrial (River Aire and River Calder, Yorkshire, UK) and rural environments (River Thames, Oxfordshire, UK) to study the biodegradation potential of the key steroid estrogen 17β-estradiol (E2) and its synthetic derivate ethinylestradiol (EE2). Microorganisms in the river water samples were capable of transforming E2 to estrone (E1) with half-lives of 0.2 to 9 d when incubated at 20°C. The E1 was then further degraded at similar rates. The most rapid biodegradation rates were associated with the downstream summer samples of the River Aire and River Calder. E2 degradation rates were similar for spiking concentrations throughout the range of 20 ng/L to 500 μg/L. Microbial cleavage of the steroid ring system was demonstrated by release of radiolabeled CO2 from the aromatic ring of E2 (position 4). When E2 was degraded, the loss of estrogenicity, measured by the yeast estrogen screen (YES) assay, closely followed the loss of the parent molecule. Thus, apart from the transient formation of E1, the degradation of E2 does not form other significantly estrogenic intermediates. The E2 could also be degraded when incubated with anaerobic bed sediments. Compared to E2, EE2 was much more resistant to biodegradation, but both E2 and EE2 were susceptible to photodegradation, with half-lives in the order of 10 d under ideal conditions.