bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear alkylbenzenesulfonate (LAS) surfactants in a simple test to detect refractory organic carbon (ROC): Attribution of recalcitrants to impurities in LAS
Authors: Kölbener Pius , Baumann Urs , Leisinger Thomas , Cook Alasdair M.
Published: March 2010

The standard procedure to examine the biodegradability of a (group of) compound(s) in a trickling filter is a continuous-flow system. In this test, nondegraded metabolites from a commercial linear alkylbenzenesulfonate (LAS) surfactant are detected (Kölbener, Baumann, Leisinger, and Cook; accompanying paper). This procedure has now been augmented by two phases in closed cycle to give a test for refractory organic carbon (ROC test). First, the concentration of nondegraded metabolites was increased by readdition of LAS to the solution being cycled through the filter. Second, the concentrated residues were further recycled till the net dissolved organic carbon (DOC) stabilised at a finite value and the net released CO2 stabilised at about zero. The organic compounds remaining at this phase of the experiment were considered recalcitrant and could be examined by global (e.g., DOC) and specific (e.g., HPLC) assays. Four different commercial preparations of LAS were examined, as were the (4-sulfophenyl)undecane homologue (C11-LAS), the (4-sulfophenyl)dodecane homologue (C12-LAS), and some related compounds. The four commercial LAS preparations contained different levels of impurities (2% to about 17%, according to the producers), which were largely dialkyltetralinesulfonates (DATS) and branched-chain alkylbenzenesulfonates (bABS). The refractory organic carbon (ROC) remaining after biodegradation varied from 3 to 14%. The results were a characteristic of the LAS under study and were independent of the source of the biomass used in the experiment. Residues were examined by HPLC, and 50 to 100 peaks were observed, which were usually characteristic of the LAS studied. No peak has been conclusively identified. We consider the recalcitrants to represent carboxylated DATS and carboxylated bABS.
Comparisons of the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on chemically impacted and nonimpacted subpopulations of Fundulus heteroclitus: I. TCDD toxicity
Authors: Prince Ruth , Cooper Keith R.
Published: March 2010

A subpopulation of Fundulus heteroclitus inhabiting the chemically impacted estuary of Newark Bay, New Jersey, was found to be resistant to the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as compared to a chemically non-impacted subpopulation of F. heteroclitus in Tuckerton, New Jersey. The Newark/Raritan Bay estuary is a major site of TCDD contamination. The Newark F. heteroclitus embryos, when exposed to 12 to 100 parts per trillion (pptr) [3H]TCDD/acetone (nominal water concentrations) did not exhibit TCDD-dependent lesions or death. In contrast, the Tuckerton embryos exhibited both TCDD concentration-related lesions and death that was associated with the lesions. The Newark embryonic resistance to TCDD toxicity could not be attributed to a lesser absorption of [3H]TCDD as compared to the Tuckerton embryos. The Newark F. heteroclitus adult fish, when dermally treated with 0.30 to 60 ng/g [3H]TCDD/DMSO, did not exhibit TCDD treatment-related increases in death, lesions, or liver-to-body-weight ratios, whereas the Tuckerton adult fish did. The Newark fish did exhibit greater parasitic infestations of the liver, greater hepatic neoplasias, and greater liver-to-body-weight ratios, all of which were independent of laboratory TCDD treatment, as compared to the Tuckerton fish. These hepatic effects in the Newark fish may be indicative of the chronic chemical exposure of this F. heteroclitus subpopulation.
Comparisons of the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on chemically impacted and nonimpacted subpopulations ofFundulus heteroclitus: II. metabolic considerations
Authors: Prince Ruth , Cooper Keith R.
Published: March 2010

A previous paper reported resistance to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity in a subpopulation of Fundulus heteroclitus inhabiting the chemically impacted estuary of Newark Bay, New Jersey, as compared to a chemically nonimpacted subpopulation of F. heteroclitus in Tuckerton, New Jersey. This paper reports the results of toxicokinetic and metabolic investigations. The rates of [3H]TCDD elimination following a single dermal treatment of [3H]TCDD were similar between the Newark and Tuckerton F. heteroclitus subpopulations, as were the capabilities to metabolize TCDD. The Newark F. heteroclitus subpopulation consistently exhibited elevated hepatic P4501A catalytic activity (two- to fivefold), as measured by ethoxyresorufin O-deethylase (EROD), compared to the Tuckerton subpopulation. EROD activity in Newark F. heteroclitus could not be induced by dermally administered [3H]TCDD, ranging from 0.020 to 8.0 ng/g [3H]TCDD. The Tuckerton fish exhibited a linear increase in EROD activity at 96 h following dermal administration of [3H]TCDD, ranging from 0.80 to 8.0 ng/g [3H]TCDD. The maximum mean induction in the Tuckerton fish was 30-fold greater than the Tuckerton vehicle control mean. These data indicate that the Newark fish were resistant to both the toxicity of TCDD and the ability of TCDD to induce P4501A activity, which may imply an alteration in the Ah receptor complex of Newark F. heteroclitus.
A QSAR for steroidal compound interaction with cytochrome P4501A1
Authors: Chan Zenith , Hoixebone B. R.
Published: March 2010

The well-known binding and metabolism of polycyclic aromatic hydrocarbons (PAHs) by cytochrome P4501A1 has led to a proposed metabolic specialization of P4501A1 to endogenous hormones. To assess this hypothesis, the binding affinities of nine steroidal molecules of increasing multiple bond content and the aromatic compound chrysene were tested against a standard ethoxyresorufin O-deethylation assay. Both the hydrophobicity and the planarity of these molecules correlate to their binding efficiency. However, the product of these two properties shows a much stronger correlation than each separately. By using standard mathematical identities, hydrophobicity and planarity can be related to the enthalpy and entropy of activation, respectively. In this model, the hydrophobicity represents the adhesiveness per unit contact area with the active site, and the planarity the proportion of molecular structures in contact with the site. The net adhesiveness is therefore accidentally largest for the xenobiotic PAH structures.
Assessment of experimental data on PCB-induced reproduction inhibition in mink, based on an isomer- and congener-specific approach using 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalency
Authors: Leonards Pim E. G. , De Vries Theo H. , Minnaard Wim , Stuijfzand Suzanne , De Voogt Pim , Cofino Wim P. , van Straalen Nico M. , van Hattum Bert
Published: March 2010

This paper describes an attempt to derive a median effect level (EC50) of PCBs for reproduction of mink based on experimental literature data. Unfortunately, the conditions of the mink studies carried out during the last two decades vary widely, which makes it difficult to establish unequivocal dose-effect relationships. This study describes an attempt to correct for the differences in exposure time using a one-compartment bioaccumulation model. This model estimates the whole-body concentration of PCBs in mink. Two approaches are tested. First, the whole-body concentration of 10 isomer groups of PCBs in mink were estimated and compared with reproduction data to calculate an EC50 value. Alternatively, estimates for the whole-body concentration in mink of 11 individual biologically active PCB congeners were made. With these, the toxic equivalent concentration (TEC) in mink was estimated using the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent factor (TEF) approach. Whole-body dose-effect relationships were estimated and EC50 values for litter size and kit survival were calculated. The application of the one-compartment bioaccumulation model of the first approach resulted in a significant improvement in the dose-effect relationship in comparison to the raw data set. A further improvement in this relationship was achieved using the congener-specific bioaccumulation model in combination with the TEF approach. This study proposes a critical body residue (EC50) for mink litter size of 1.2 μg/g (total PCBs/wet weight). From the second approach a critical body residue (EC50) expressed in TCDD equivalency for litter size of 160 pg/g (TCDD equivalence/wet weight) and 200 ng/g (TCDD equivalence/wet weight) for kit survival is proposed.
Hepatic cytochrome P4501A induction in DAB (Limanda limanda) after oral dosing with the polychlorinated biphenyl mixture clophen A40
Authors: Sleiderink Hedwig M. , Everaarts Jan M. , Goksøyr Anders , Boon Jan P.
Published: March 2010

The flatfish dab (Limanda limanda) serves as an indicator species in pollution monitoring programmes in the North Sea. The present study investigated the induction response of the monooxygenase system and haematological changes in female dab after multiple administrations of a technical mixture of polychlorinated biphenyls (PCBs). Mature female dab were dosed with 1 mg of the PCB mixture Clophen A40 (Clo A40) in sunflower oil every 6 weeks, with a maximum of three doses per fish. In all PCB-administered groups, levels of cytochrome P4501A (CYP1A) protein, measured with a semi-quantitative ELISA method, and 7-ethoxyresorufin O-deethylase (EROD) activity showed a three- to ninefold induction 14 d after dosing compared with control groups, smaller but also significant increases were observed in total cytochrome P450 (Σ P450) levels. Although the PCB concentrations and the corresponding toxic equivalent (TEQ) value in muscle tissue still increased after administration of the second and third dose of Clo A40, maximum responses of the EROD activity were already reached after the first dose at a TEQ value for chlorinated biphenyls (CB-TEQ) of 2 ng/g lipid. The PCB patterns of liver and muscle tissue of female dab from the central North Sea were found to be virtually identical. Hence, the use of PCB concentrations in muscle as a qualitative model for changes in the liver appears legitimate. Haemoglobin concentrations were elevated after the third dose of Clo A40, whereas haematocrit values and the mean corpuscular haemoglobin concentration (MCHC) between treated and control groups did not differ.
Influence of pH on the toxicity of ammonia toChironomus tentansandLumbriculus variegatus
Authors: Schubaur-Berigan Mary K. , Monson Philip D. , West Corlis W. , Ankley Gerald T.
Published: March 2010

The U.S. Environmental Protection Agency water-quality criteria establish permissible levels of ammonia in the nation's fresh waters. These criteria are based on accumulated research suggesting that, for most aquatic species (primarily fishes), the toxicity of un-ionized ammonia predominates over that of the ammonium ion. The development of a sediment-quality criterion for ammonia requires evaluation of the relative toxicity of the two ammonia forms to benthic and epibenthic macroinvertebrates to determine whether the water-quality toxicity model can be applied to sediments. Flow-through ammonia toxicity tests were conducted over 10 d with the oligochaete Lumbriculus variegatus and the larval midge Chironomus tentans at four pH values (6.3, 7.2, 7.8, and 8.6) using a unique pH control system. Total ammonia was more toxic at elevated than at low pH to both species, suggesting that un-ionized ammonia (more prevalent at high pH) is important in determining the toxicity of ammonia to these two species. Hardness or alkalinity differences in the range of 30 to 200 mg/kg (as CaC03) did not appear to affect the toxicity of ammonia to the two species in separate 4-d tests. Based on results of the 10-d tests, the joint toxicity/pH model that establishes the water-quality criterion value for ammonia appears to be sufficiently protective of L. variegatus and C. tentans, by factors of at least 3 and 10, respectively. However, this study did not address potential differences in exposure of benthic organisms to ammonia in sediments vs. that in the water column; nor were the chronic effects of ammonia on these species measured in this study.
Endocrine and metabolic dysfunction in yellow perch, Perca flavescens, exposed to organic contaminants and heavy metals in the ST. Lawrence river
Authors: Hontela Alice , Dumont Pierre , Duclos Dominick , Fortin RÉJean
Published: March 2010

The endocrine and biochemical responses to the acute stress of capture and handling were investigated in sexually mature and in immature male and female yellow perch, Perca flavescens, from a site contaminated by organic contaminants (PAHs and PCBs) and heavy metals (Hg, Cd, As, and Zn) and from a reference site in the St. Lawrence River. Following a standardized capture and handling stress, fish from the contaminated site did not exhibit the expected physiological stress response observed in fish from the reference site. Blood Cortisol and thyroxine levels were lower, and liver glycogen stores were greater in mature males and females, as well as in the immature fish from the contaminated site, compared to the reference site. Fish from the contaminated site also had smaller gonads and lower condition factor. The impaired ability to elevate blood Cortisol in response to an acute stress may be used as a biomarker of toxic stress in health assessment of feral fish from polluted environments.
Uptake and loss of Bacillus thuringiensis var. israelensis by Daphnia magna in laboratory exposure
Authors: Vaishnav Dinesh D. , Anderson Richard L.
Published: March 2010

We determined the ingestion and loss of the spores of Bacillus thuringiensis var. israelensis (Bti) by a nontarget organism Daphnia magna. Daphnids were either not fed or fed during the exposure to the spores. The results showed that (a) the uptake rates with unfed and fed daphnids were approximately first-order with respect to spore concentration, and the rate constants for unfed and fed daphnids were 5.5 × 10−5 and 1.4 × 10−7 L daphnid−1 h−1, respectively, and (b) unfed and fed daphnids rapidly depurated the majority of the accumulated spores, and the depuration rate constants for unfed and fed daphnids were 0.13 and 0.15 h−1, respectively.
Equilibrium studies in natural waters: Speciation of phenolic compounds in synthetic seawater at different salinities
Authors: Gianguzza Antonio , De Stefano Concetta , Sammartano Silvio , Demianov Piotr
Published: March 2010

Interactions between some phenolic compounds and macro-constituents of synthetic seawater (Na+, K+, Ca2+, Mg2+, Cl−, and SO2−4), at 20, 35, and 45%0 salinity, have been investigated potentiometrically by using the [H]-glass electrode. The formation constants of phenol, o- and p-cresol, o- and p-nitrophenol complexes with sodium, potassium, calcium, and magnesium ions have been determined in the ionic strength range 0 ≤ I ≤ 1 mol/L. A comparison between the apparent protonation constants of phenols determined in synthetic seawater, and those simulated by a suitable complex formation model, is discussed. The possibility of calculating, by simulation, the apparent protonation constants of some chlorophenolic compounds in synthetic seawater is also reported.
Quantification of metallothionein as a biomarker for cadmium exposure in terrestrial gastropods
Authors: Berger Burkhard , Dallinger Reinhard , Thomaser Astrid
Published: March 2010

A useful cadmium saturation method, the cadmium-Chelex assay, is adopted and modified for quantification of metallothionein induction and protein cadmium saturation in midgut gland of cadmium-exposed Roman snails (Helix pomatia). The assay is based on denaturation of nonmetallothionein, cadmium-binding ligands; complete saturation of metallothionein by adding excess amounts of nonradioactive cadmium; and chelating of excessive amounts of cytosolic metal by the Chelex-100 cation exchange resin. After short-term cadmium feeding, snails quickly responded by showing rising metallothionein levels, protein concentrations in the midgut gland increasing from about 300 μg/g tissue (wet weight) to 750 μg/g within a period of 2 d. At the same time cadmium loading of protein rose form 20% in control snails to 50% saturation in exposed individuals. After long-term cadmium exposure, maximal metallothionein concentrations of about 1,000 μg/g tissue (wet weight) and a relative metallothionein cadmium saturation of 70% were reached in midgut glands of exposed snails. It is proposed that metallothionein quantification in H. pomatia might be used as a tool for biomarker studies in three ways. First, the slope of metallothionein induction might be used as a biomarker for incipient cadmium exposure and for the responsiveness of an invertebrate to metal exposure stress. Second, the steady-state level of metallothionein concentration in the midgut gland of H. pomatia might serve as an integrating biomarker reflecting single or repeated exposure events occurring over a prolonged period of time. Third, the percentage cadmium saturation of metallothionein could be utilized as a biomarker indicating if and by how much the detoxification capacity of H. pomatia is becoming exhausted due to elevated cadmium exposure.
To normalize or not to normalize? Fat is the question
Authors: Hebert Craig E. , Keenleyside Karen A.
Published: March 2010

Concentrations of lipophilic contaminants in biota are frequently corrected for variation in tissue lipid content. Usually, this correction is accomplished by dividing tissue contaminant concentration by lipid concentration to form lipid-normalized data. This ratio-based approach is satisfactory when contaminant concentration varies in direct proportion to lipid content. However, when such a relationship does not exist, erroneous conclusions may be reached. Recent research has emphasized the potential shortcomings of the use of ratio variables. We demonstrate the importance of considering these shortcomings when lipid-normalizing data. Three examples are presented, and an alternative approach based upon the use of analysis of covariance (ANCOVA) is suggested.
Mercury and cadmium uptake from seawater and from food by the Norway lobster Nephrops norvegicus
Authors: Canli Mustafa , Furness Robert W.
Published: March 2010

Norway lobsters, Nephrops norvegicus, were fed on a mercury- and cadmium-rich diet for up to 50 d or were exposed to sublethal concentrations of organic mercury, inorganic mercury, or cadmium in seawater for 30 d. Cadmium taken up from seawater accumulated mainly in the hepatopancreas and gill, while it accumulated mainly in the hepatopancreas after feeding. Both organic and inorganic mercury taken up from seawater accumulated mainly in the gill, while highest concentrations were found in the hepatopancreas after the feeding experiment. Accumulation of organic mercury was higher than that of inorganic mercury. Although all treatments resulted in the accumulation of mercury and cadmium from seawater and food, tissue distribution of metals differed significantly among treatments. Distributions of organic and inorganic mercury also varied among tissues after uptake from seawater, with organic mercury being more evenly distributed among tissues than inorganic mercury, the latter being found predominantly in the gill.
Evaluation of liver histopathology and erod activity in St. Lawrence lake sturgeon (Acipenser fulvescens) in comparison with a reference population
Authors: Rousseaux Colin G. , Branchaud A. , Spear Philip A.
Published: March 2010

In an attempt to evaluate the effects of contaminants on the lake sturgeon Acipenser fulvescens, fish were netted from two sites: Rivière des Prairies, confluent with the St. Lawrence River near Montréal, and a reference site on the upper reaches of the Ottawa River in the La Verendrye Park. Livers of fish collected from the Rivière des Prairies were difficult to homogenize, and they left behind strands of what appeared to be connective tissue. Suspecting hepatic fibrosis, we decided to evaluate the livers for histopathologic changes. Nineteen adult lake sturgeon (eleven male and eight female) were examined. Following fixation, routine processing, sectioning, and staining with hematoxylin and eosin, microscopic evaluation revealed the following: Sections taken from livers of fish from the Rivière des Prairies site showed excessive fat accumulation and often severe chronic-active cholangiohepatitis. Bile duct proliferation (p < 0.0001), periportal fibrosis (p < 0.0001), inflammation (p < 0.001), and fat accumulation (p < 0.05) were more pronounced in the fish from the Rivière des Prairies site. Melano-macrophage centres appeared to be both paler and gave the appearance of fewer numbers (p < 0.01). Livers from lake sturgeon taken from the reference site had a more normal appearance. The EROD levels were also significantly induced in these fish (reference 3.39 ± 0.57; Rivière des Prairies site 8.21 ± 0.87 pmol/mg protein/min; p < 0.0005). The EROD levels positively correlated with bile duct proliferation (r2 = 0.44; p = 0.001) and periportal fibrosis (r2 = 0.41; p = 0.002). Despite the statistical associations above, we cannot categorically state that contaminants are the sole cause of the lesions seen.
Phototoxic response ofLumbriculus variegatusto sediments contaminated by polycyclic aromatic hydrocarbons
Authors: Monson Philip D. , Ankley Gerald T. , Kosian Patricia A.
Published: March 2010

The toxicity of certain polycyclic aromatic hydrocarbons (PAHs) to aquatic organisms can be greatly increased upon exposure of the organisms to ultraviolet (UV) radiation present in sunlight. The phenomenon of photoactivation of PAHs had received some attention in the laboratory; however, evaluation of the photoinduced toxicity of PAHs in field settings has been limited. In our studies, in situ chambers made from Pyrexr̀ glass tubes were used to evaluate the phototoxic response of laboratory-cultured oligochaetes (Lumbriculus variegatus) in sediments contaminated with PAHs. These experiments were conducted using both sunlight-exposed and shaded test chambers. In addition to the PAH-contaminated site, a reference site lacking PAHs was tested as a control. Survival of L. variegatus at the PAH-contaminated site was significantly less in chambers exposed to sunlight than in chambers held in the dark, or chambers from the reference site. Concurrent laboratory studies with sediment collected from the two sites and an artificial source of UV light corroborated observations made in the field. Although a number of PAHs were present at elevated concentrations in the test sample, further work is required to determine exactly which were responsible for the observed phototoxicity.
Predicting algal sensitivity to a pesticide stress
Authors: Kent Robert A. , Currie David
Published: March 2010

Twelve freshwater phytoplankton species were used to investigate the factors affecting the toxicity of the organo-phosphorus insecticide fenitrothion (O,O-dimethyl-O-nitro-m-tolyl phosphorothioate) to algae. The unicellular chlorophytes Ankistrodesmus falcatus, Chlamydomonas segnis, Chlamydomonas reinhardtii, Chlorella pyrenoidosa, Chlorella vulgaris, Cosmarium sp., Pediastrum sp., Scenedesmus obliquus, Selenastrum capricornutum, and Staurastrum sp.; the bacillariophyte Navicula sp.; and the cyanophyte Anabaena sp. were exposed to three concentrations (0.1, 1.0, and 10.0 mg/L) of fenitrothion. Differential growth effects were observed among the species exposed to fenitrothion over short (96 h) and long-term (14 d) durations. Fenitrothion concentrations eliciting a 50% growth reduction over 96 h (EC50) ranged from 0.8 to 24.4 mg/L. Selected properties of the test algae (cell size, lipid content, and bioconcentration capacity) were measured and examined for their relationship to fenitrothion sensitivity. Strong correlations were obtained between fenitrothion sensitivity and cell surface area/volume (S/V) ratios, cell lipid content, and fenitrothion bioconcentration capacity of the cells, suggesting that these attributes may be useful predictors of differential sensitivity to lipophilic xenobiotics in unicellular phytoplankton. A positive relationship observed between cell S/V ratio and the bioconcentration of fenitrothion further implicates algal cell size as a significant factor in alga/pesticide interaction and subsequent vulnerability to lipophilic xenobiotics.
Comparative sensitivity of amphibian tadpoles to single and pulsed exposures of the forest-use insecticide fenitrothion
Authors: Berrill Michael , Bertram Susan , Coulson Donna , Kolohon Mark , Ostrander Dean , Pauli Bruce
Published: March 2010

The insecticide fenitrothion is sprayed twice, 5 to 10 d apart, to control spruce budworm. To assess the effects of pulsed exposure of fenitrothion to different species of amphibians, we exposed 1- and 8-d-old tadpoles of wood frogs, leopard frogs, green frogs, bullfrogs, and American toads, as well as larvae of the spotted salamander, to 2 to 9 ppm of the insecticide for 24 h. Our results indicate that within each ranid species, day-1 and day-8 tadpoles are equally sensitive, and tadpoles exposed twice, on day 1 and day 8, are no more sensitive to the second exposure than to the first. Bullfrog and green frog tadpoles are more sensitive to exposures than are wood frog and leopard frog tadpoles, exhibiting paralysis at lower concentrations, and they are affected by exposure to the carrier compounds as well as the insecticide. The greater sensitivity of the green frog and bullfrog tadpoles correlates with their smaller size and earlier developmental stage at hatching. American toad tadpoles are more tolerant of pu sed exposure to fenitrothion than are any of the ranids, whereas the spotted salamander larvae are as sensitive as are the bullfrog and green frog tadpoles.
The effects of motorway runoff on freshwater ecosystems: 2. Identifying major toxicants
Authors: Maltby Lorraine , Boxall Alistair B.A. , Forrow David M. , Calow Peter , Betton Clifford I.
Published: March 2010

Previous studies have provided prima facie evidence that runoff from the Ml motorway, UK, affects both the quality of the receiving water and the biota living there, in sites short distances from point sources —i.e., possible worst-case situations. Because discharges contain a wide variety of contaminants, both the identification of toxicants and the establishment of causal relationships between observed changes in water/sediment quality and biology are often difficult. In this particular case, the problem was addressed by conducting a series of toxicity tests using the benthic amphipod Gammarus pulex. The abundance of this species was greatly reduced downstream of the point where motorway runoff entered the stream. Stream water contaminated with motorway runoff was not toxic to G. pulex. However, exposure to contaminated sediments resulted in a slight reduction in survival over 14 d, and sediment manipulation experiments identified hydrocarbons, copper, and zinc as potential toxicants. Spiking experiments confirmed the importance of hydrocarbons, and fractionation studies indicated that most of the observed toxicity was due to the fraction containing polycyclic aromatic hydrocarbons. Animals exposed to contaminated sediments and water spiked with sediment extract accumulated aromatic hydrocarbons in direct proportion to exposure concentrations.
Organotins in freshwater harbors and rivers: Temporal distribution, annual trends and fate
Authors: Pent Karl , Hunn Judith
Published: March 2010

The occurrence of butyltin and phenyltin compounds in water, mussels, and sediment of freshwater boat harbors of Lake Lucerne, Switzerland, and six Swiss river systems was determined between 1991 and 1993 following the sales ban of organotin-containing antifouling paints. In harbor waters, average levels of tributyltin (TBT) were between 40 and 50 ng/L in 1993, which was one order of magnitude lower than in 1988. Residues of up to 9.2 μg/g TBT and 0.7 μg/g triphenyltin (TPT) occurred in zebra mussels (Dreissena polymorpha) and were related to the water concentrations. In a sediment core, high levels of TBT and TPT occurred in the upper 7 cm and 5.5 cm, respectively, with significant decreases below. Estimated sedimentation rates and the fact that transformation products did not increase with depth indicate that TBT and TPT are persistent in these sediments. In all rivers, di- and/or monobutyltin of up to 46 ng/L occurred consistently, and occasionally TBT and TPT of up to 26 and 11 ng/L, respectively. This study indicates that even though regulations were effective in reducing TBT and TPT levels in boat harbor water, contamination of surface fresh waters including rivers by organotin compounds is still widespread and has ecotoxicological consequences. Moreover, harbor sediments represent long-term reservoirs of these compounds.
Quantitative structure-activity relationships for evaluating the influence of sorbate structure on sorption of organic compounds by soil
Authors: Hu Qinhong , Wang Xiaojiang , Brusseau Mark L.
Published: March 2010

The purpose of this work was to investigate the effect of sorbate structure, by using the quantitative structure-activity relationship (QSAR) approach, on sorption of organic compounds by two soils with different amounts of organic matter. Miscible displacement experiments were performed with several organic contaminants representing six classes of nonpolar, nonionizable organic chemicals, including chlorinated aliphatics, chlorobenzenes, polycyclic aromatic hydrocarbons (PAHs), n-alkylbenzenes, methylated benzenes, and polychlorinated biphenyls (PCBs). The breakthrough curves were analyzed by using a bicontinuum model wherein sorption is assumed to be instantaneous for a fraction of the sorbent and rate limited for the remainder. The QSAR approach was used to investigate the dependency of both equilibrium and nonequilibrium sorption coefficients on topological descriptors representing structural properties of the solutes. For both equilibrium and nonequilibrium parameters, the first-order valence molecular connectivity (1Xv) was found to be the best topological descriptor. Most of the rate-limited sorption behavior could be explained by accounting for the size and structure of the solute molecule, as indicated by the good correlation between the rate coefficient and 1Xv. This supports the contention that rate-limited sorption in these systems is controlled by a physical diffusion mechanism, consistent with the polymer diffusion model. Based on this model, the calculated diffusion-length ratios for the Borden and Mt. Lemmon soils, which have a large difference in organic-matter contents, compare favorably to the values determined from the measured rate data.
Evaluation of alternative reference toxicants for use in the earthworm toxicity test
Authors: Yeardley Roger B. , Lazorchak James M. , Pence Michael A.
Published: March 2010

The use of the 14-d earthworm toxicity test to aid in the evaluation of the ecological impact of contaminated soils is becoming increasingly widespread. However, the method is in need of further standardization. As part of this continuing process, the choice of reference toxicants was evaluated. Reference toxicants were rated in relation to the following criteria: (a) reproducibility, (b) low human health hazard, (c) feasibility of measurement, and (d) chemical stability. Potassium chloride (KCl) and ammonium chloride (NH4Cl) were evaluated as possible alternatives to the one currently in common use, 2-chloroacetamide. Potassium chloride rated the best for the combination of the four criteria, followed by NH4Cl and 2-chloroacetamide. Coefficients of variation (C.V.s) from control charts of six definitive tests were used to measure reproducibility. The best reproducibility (lowest C.V.) was shown by KCl, followed by NH4Cl and 2-chloroacetamide. Toxicants ranked KCl < NH4Cl ≪ 2-chloroacetamide in terms of health hazard; and KCl = NH4Cl > 2-chloroacetamide in terms of measurement feasibility. Both 2-chloroacetamide and NH4Cl changed in concentration during testing. Evidence is also presented that 2-chloroacetamide degrades rapidly during testing, and that, as dead worms decay, ammonification may be adding another toxicant, ammonia, to tests.
Combinatory effects of temperature stress and nonionic organic pollutants on stress protein (hsp70) gene expression in the freshwater sponge Ephydatia fluviatilis
Authors: Müller Werner E.G. , Koziol Claudia , Dapper Jutta , Kurelec Branko , Batel Renato , Rinkevich Baruch
Published: March 2010

This is the first documentation of a heat shock protein (hsp) response in sponges. Subjecting the freshwater sponge Ephydatia fluviatilis to temperature stress (18° to 33°C; 2 h) resulted in an increased expression (>10 times) of the Mr 70,000 (hsp70). The induction of hsp70 could be demonstrated on the level of gene expression and by quantification of the hsp70 protein. Temperature stress also resulted in a 25% reduction of sponge cell proliferation. A mixture of nonionic organic compounds was extracted from water from the polluted Schwarzbach River (S. Hesse, Germany) by adsorption onto XAD-7 resin. Concentrations of this Schwarzbach River water extract at two and four times ambient levels resulted in decreases in cell proliferation by 53.6 and 99.4%, respectively. However, when cells were exposed to these levels of the Schwarzbach River water extract directly following a temperature stress (33°C for 2 h), cell proliferation was less affected by the extract than the absence of the temperature stress. In addition, the combination of temperature stress and exposure to the Schwarzbach River water extract resulted in higher levels of hsp70 than were observed for each stressor by itself. Northern and Western blotting as well as precipitation assays confirmed the interaction between heat treatment and exposure to different amounts of nonionic organic pollutants on the level of mRNA and protein expression of hsp70. From these data we conclude that a sublethal treatment of sponges with heat results in a higher tolerance of the animals to chemical stressors. These results are relevant to the real-world situation where organisms are often exposed simultaneously to a variety of stressors, in contrast to many laboratory exposures that aim to elucidate the effects of individual stressors.
Comparative photodegradation rates of alachlor and bentazone in natural water and determination of breakdown products
Authors: Chiron Serge , Barceló Damià , Abian Joaquin , Ferrer Marta , Sanchez-Baeza Francisco , Messeguer Angel
Published: March 2010

The photochemical degradation of the herbicides alachlor (2-chloro-2′,6′-diethyl-N-methoxymethylacetanilide) and bentazone (3-isopropyl-(1H)-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide) in distilled water and in river water, under xenon arc lamp irradiation, was investigated. Analytical determinations were carried out by using a xenon arc photoreactor and online solid-phase extraction coupled to liquid-chromatography diode-array and liquid-chromatography mass-spectrometry detection systems. Photolysis experiments were performed at low concentration (20 μg/L), and the advantages of this methodology over conventional techniques are discussed. The photodegradation of alachlor and bentazone is a process depending on the water type, humic substances, and pH. When using a solution of 4 mg/L of humic matter, the estimated alachlor and bentazone half-lives were 84 and 150 min, respectively, using a total irradiance of 550 W/m2 in the range of 300 to 800 nm. The degradation of alachlor and bentazone followed pseudo second- and first-order kinetics, respectively. The major photodegradation products of both herbicides were identified either by on-line solid-phase extraction (SPE)-liquid chromatography-thermospray mass spectrometry (LC/TSP-MS) or on-line-SPE-LC/TSP-tandem mass spectrometry (LC/TSP-MS/MS). In addition to that, a total of six transformation products of alachlor were synthesized in our laboratory and their MS spectra were compared with those of the breakdown products obtained. After photodegradation, a total of 14 photoproducts resulted from alachlor dechlorination with subsequent hydroxylation and cyclization processes. The two major photoproducts were identified as hydroxy-alachlor and 8-ethyl-1-methoxymethyl-4-methyl-2-oxo-1,2,3,4-tetrahydroquinone. No significant breakdown products of bentazone could be identified.
Toxicity of aircraft de-icer and anti-icer solutions to aquatic organisms
Authors: Hartwell S. Ian , Jordahl David M. , Evans Joyce E. , May Eric B.
Published: March 2010

Laboratory studies were undertaken to assess the toxicity of industrial mixtures of aviation de-icers and anti-icers. Various additives and contaminants are present in these solutions at proportions of 10 to 20% of the total volume. Staticrenewal toxicity tests were performed at concentrations that bracketed published LC50 values for the primary ingredients (9-51 ml glycol/L) using fathead minnow (Pimephales promelas), Daphnia magna, Daphnia pulex, Ceriodaphnia dubia, and Photobacterium phosphoreum (Microtoxr̀) bioassays. Water from a stream that receives runoff from a large commercial airport was also tested during a late winter storm (March), and spring baseflow (April). The anti-icer solution was more toxic than the de-icer solution by two orders of magnitude (96-h LC50 range 0.03–0.44 ml/L, 3.02–13.48 ml/L, respectively). Both types of solutions exhibited greater toxicity than previously reported values for the primary ingredients. Toxic effects were observed in the March stream sample, but not the April sample. Significant inhibition of reproduction in C. dubia in the anti-icer and de-icer solutions occurred at 0.05 and 0.38 ml/L, respectively. Effects were observed in the Microtox assay at concentrations of 0.125 and 0.25 ml/L for the anti-icer and de-icer, respectively. Results suggest that the additives, rather than the glycols, are the major source of toxicity. Histological damage observed in fathead minnows primarily involved gill, kidney, and skin tissue, with the most prominent responses seen in fish exposed to the anti-icer solution. The de-icer solution elicited respiratory epithelial “disruption” and renal damage, and the anti-icer caused proliferative branchitis (hyperplastic response) and delamination of the epidermis from the dermis of the skin.
Overview and rationale for developing regulatory guidelines for nontarget plant testing with chemical pesticides
Authors: Boutin Céline , Freemark Kathryn E. , Keddy Cathy J.
Published: March 2010

In the assessment of ecological risk posed by pesticide use, much greater emphasis has been given to the direct effects on wildlife than on impacts on wildlife habitat. Assessment of indirect effects to wildlife entails an evaluation of pesticide toxicity to plant species (and invertebrates) that make up wildlife habitats. Under the pesticide registration process in Canada and in most other countries, there is no specific requirement for testing the toxicity of pesticides to nontarget plants other than agronomically important species. The proposed nontarget plant testing guidelines summarized in this paper are intended to fill this gap. The chief objectives of the guidelines are to outline data requirements, to suggest methods and approaches for generating the data required, and to facilitate and improve hazard assessment for nontarget plants (and habitats) as a result of chemical pesticide use. The rationale behind decisions reached in the guidelines is also presented. The proposed guidelines are very flexible, as registrants may be granted a waiver for any test required, provided the rationale is justified on appropriate scientific grounds. Harmonization and comparison with other guidelines are discussed. These proposed nontarget plant testing guidelines can serve as a basis for guideline development or modernization for other jurisdictions.
Successive changes in bacterioplankton communities in the river rhine after copper additions
Authors: Tubbing Diny M.J. , Admiraal Wim , Katako Albert
Published: March 2010

The sensitivity of bacterioplankton to copper was analyzed to see whether initial steps in the selection of copper-tolerant life-forms in mixed populations of bacteria were accompanied by changes in basic metabolic parameters. Analysis took place by measuring the incorporation of [3H]thymidine and [3H]leucine, and the hydrolysis of leucyl-β-naphthylamide over a period of 4 d. In acute toxicity tests the radiochemically determined parameters showed the same sensitivities to copper, whereas in the enzyme test the dose-response curve had a much lower slope, indicating less sensitivity. Marked differences were observed in the susceptibility of the different processes after prolonged exposure to copper. Incorporation of [3H]thymidine, [3H]leucine, and proteolytic activity changed substantially during exposure to concentrations as low as 2 to 31 μg Cu L−1. Higher copper concentrations (126-1,000 μg Cu L−1) led in the course of 24 to 48 h to the development of a bacterial community with a higher overall copper tolerance. In winter, these successive events in bacterial populations were observed in the absence of substantial populations of algae or zooplankton. In summer, the metabolic changes in bacterioplankton exposed to copper were strongly affected by the poisoning of other organisms, notably algae, and the subsequent release of organic material. Thus, moderate copper concentrations alter the metabolic profile of bacterial communities, probably as an initial step in the selection of tolerant life-forms.
Bioavailability of polycyclic aromatic hydrocarbons from a historically contaminated sediment core
Authors: Harkey Gail A. , van Hoof Patricia L. , Landrum Peter F.
Published: March 2010

To determine changes in bioavailability of selected polycyclic aromatic hydrocarbons (PAHs) with sediment aging, Lumbriculus variegatus were exposed for 4 weeks to sediment core sections taken from a contaminated lake. Core depths included surficial (0 to 4 cm), 4- to 8-, 12- to 16-, 28- to 32-, and 44- to 48-cm sections deposited from approximately 1899 to 1993, and were known to be historically contaminated with PAHs. Bioaccumulation was maximal at the 12- to 16-cm depth (circa 1967) where sediment PAH concentrations were greatest. Accumulation was generally below detection limits in the 0- to 4-cm depths, even though sediment concentrations of some compounds were comparable to those at the 12- to 16-cm depth where accumulation was great enough to generate accurate kinetics curves. Accumulation peaked at about 96 h, then declined over the remainder of the study for the lower-molecular-weight PAHs. For most higher-molecular-weight PAHs, accumulation peaked at about 2 weeks, then declined only slightly after 4 weeks. The differential bioavailability observed between surficial and at-depth core sections raises questions concerning the adequacy of results generated from toxicity and bioaccumulation tests routinely conducted with surficial sediments.
Lethal body burdens of polar narcotics: Chlorophenols
Authors: van Wezel Annemarie P. , Punte Sophie S. , Opperhuizen Antoon
Published: March 2010

The goal of the present study was to measure in fathead minnow (Pimephales promelas) the lethal body burden (LBB) of three chlorophenols that are known as polar narcotic chemicals. The LBBs of the chlorophenols were compared to LBBs of nonpolar narcotic chemicals to consider if the two classes of narcotic chemicals differ on a body burden level. The LBB of the most acidic chlorophenol was measured at two different levels of pH exposure to determine the influence of the degree of ionization on the magnitude of the LBB. Both n-octanol/water partition coefficients and n-hexane/water partition coefficients of the chlorophenols were determined at different pH levels to consider the influence of ionization on the partition coefficient and to determine the importance of a polar group in the organic phase on the partitioning behaviour. Partitioning to n-octanol and n-hexane was used as input in a model to simulate the equilibrium partitioning between hydrophobic and nonhydrophobic and target and nontarget compartments in the fish.
Use of joint toxic response to define the primary mode of toxic action for diverse industrial organic chemicals
Authors: Broderius Steven J. , Kahl Michael D. , Hoglund Marilynn D.
Published: March 2010

An important aspect of understanding how multiple toxicants jointly act involves defining the primary mode of toxic action for the chemicals of interest. We have explored the use of 96-h acute toxicity tests with juvenile fathead minnows and primarily binary chemical mixtures to define the primary acute mode of toxic action for diverse industrial organic chemicals. Our investigation mainly considered the two special cases of noninteractive joint action known as concentration (simple similar) and response (independent) addition. The different forms of joint toxicity with binary mixtures were graphically illustrated by isoboie diagrams. Designated as the mode of action-specific reference toxicants were 1-octanol, phenol, and 2,4-dimtrophenol. It was observed from binary isobole diagrams that a chemical with a similar primary mode of toxic action to that of a reference toxicant would display a concentration-addition type of joint action with the reference toxicant over the entire mixture ratio range. Dissimilar chemicals with very steep concentration-response curves generally showed an interaction that was less-than-concentration additive, but consistently demonstrated a joint toxicity that was greater than predicted by the response-addition model. The more-than-concentration additive and complex isoboles that are indicative of interactive toxicity were not commonly observed in our experiments.
Existing chemical testing for environmental fate and effects under TSCA section 4: A case study with octamethylcyclotetrasiloxane (OMCTS)
Authors: Hobson James F.
Published: March 2010

Octamethylcyclotetrasiloxane (OMCTS, or D4) is a highly volatile, cyclic silicone that is an important intermediate in the synthesis of polydimethylsiloxanes and other higher-molecular-weight silicones. As a category of chemicals, silicones have generated substantial scientific and regulatory interest over the last few years. OMCTS, one of the first silicones considered for regulatory review, was recommended for testing in the 15th Report of the Interagency Testing Committee (ITC) in 1984 based on its high volume of production, alleged presence in aquatic environments, and the general lack of environmental fate and effects information for this type of compound. As a result, the environmental effects and fate of OMCTS have been extensively evaluated in a series of laboratory toxicity and environmental fate studies, fate modeling studies, and field monitoring studies. Most of these studies were conducted as part of a negotiated consent order (CO) under Section 4 of the Toxic Substances Control Act (TSCA). Applying the principles of ecological risk assessment (ERA) to the OMCTS program, the current paper presents the problem-formulation phase of the ERA process including stressor characteristics, identification of the ecosystem potentially at risk, and development of a conceptual model. In addition, the planning phase with interactions among the industry representatives, the risk assessors, and the risk managers are discussed. OMCTS was one of the first chemicals to reach the RM1 (risk management) level of regulatory analysis under TSCA, which resulted in a determination that no additional data was needed. Application of ERA principles in this program were instrumental in this favorable determination.