bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular cloning of cytochrome P4501A cDNA of medaka (Oryzias latipes) and messenger ribonucleic acid regulation by environmental pollutants
Authors: Ryu Jisung , Lee Moon-Soon , Na Jin GYUN , Chung Kyuhyuck , Song Byoung-Joon , Park Kwangsik
Published: November 2004

The sequence of cytochrome P4501A (CYP1A) cDNA of medaka (Oryzias latipes) was determined, and its messenger ribonucleic acid (mRNA) regulation by β-naphthoflavone (βNF) was evaluated. The determined cDNA sequence contained 2,349 base pairs (bp), and the open reading frame contained a total of 1,563 bp encoding 521 predicted amino acids. The induction of CYP1A mRNA in medaka was evaluated using reverse transcription—polymerase chain reaction. The concentration—dependent induction of CYP1A mRNA in the liver was observed after exposure to βNF at nominal concentrations of 20, 100, and 500 μg/ L for 2 d. Time-dependent changes of CYP1A mRNA levels were also observed in the liver, gill, gut, and caudal fin tissues of medaka exposed to 100 μg/L of βNF for 7 d. Our results showed that the degree of CYP1A mRNA induction in the gill, gut, and caudal fin after exposure to βNF was relatively higher than that in the liver, possibly because of low basal levels of CYP1A mRNA in the gill, gut, and caudal fin of nonexposed fish. The induction of medaka CYP1A mRNA was also observed after exposure to an environmental sample, landfill leachate. The CYP1A mRNA inductions in the gill, gut, and caudal fin were also higher than that in the liver as shown in the βNF-treated groups. These results show that CYP1A mRNA determination in the gill, gut, and caudal fin, which are in direct contact with the polluted water, may become a useful method for monitoring CYP1A-inducible chemicals.
Synergistic interaction of endocrine-disrupting chemicals: Model development using an ecdysone receptor antagonist and a hormone synthesis inhibitor
Authors: Mu Xueyan , Leblanc Gerald A.
Published: November 2004

Endocrine toxicants can interfere with hormone signaling through various mechanisms. Some of these mechanisms are interrelated in a manner that might result in synergistic interactions. Here we tested the hypothesis that combined exposure to chemicals that inhibit hormone synthesis and that function as hormone receptor antagonists would result in greater-than-additive toxicity. This hypothesis was tested by assessing the effects of the ecdysteroid-synthesis inhibitor fenarimol and the ecdysteroid receptor antagonist testosterone on ecdysteroid-regulated development in the crustacean Daphnia magna. Both compounds were individually characterized for effects on the development of isolated embryos. Fenarimol caused late developmental abnormalities, consistent with its effect on offspring-derived ecdysone in the maturing embryo. Testosterone interfered with both early and late development of embryos, consistent with its ability to inhibit ecdysone provided by maternal transfer (responsible for early developmental events) or de novo ecdysone synthesis (responsible for late developmental events). We predicted that, by decreasing endogenous levels of hormone, fenarimol would enhance the likelihood of testosterone binding to and inhibiting the ecdysone receptor. Indeed, fenarimol enhanced the toxicity of testosterone, while testosterone had no effect on the toxicity of fenarimol. Algorithms were developed to predict the toxicity of combinations of these two compounds based on independent joint action (IJA) alone as well as IJA with fenarimol-on-testosterone synergy (IJA+SYN). The IJA+SYN model was highly predictive of the experimentally determined combined effects of the two compounds. These results demonstrate that some endocrine toxicants can synergize, and this synergy can be accurately predicted.
Metal dynamics of plant litter of Spartina alterniflora and Phragmites australis in Metal-Contaminated salt marshes. Part 1: Patterns of decomposition and metal uptake
Authors: Windham Lisamarie , Weis Judith S. , Weis Peddrick
Published: November 2004

To investigate the decay rate and metal uptake in litter from two species of wetland plants, leaves and stems of senescent Spartina alterniflora and Phragmites australis (P) were obtained from the Hackensack Meadowlands (NJ, USA) in October 1998, and their initial metal contents were determined. Two types of S. alterniflora were obtained, one set from a natural site (NS) and one from a restored site (RS). Leaves and stems were placed in separate litterbags, and samples of each type were reciprocally transplanted into each of the three collection sites (NS, RS, and P) as well as in the laboratory, where they were alternately dried and wetted. Litterbags were retrieved from the field at four six-month intervals and after one year from the laboratory. Annual decay coefficients were greater for leaves than for stems. Stems of P. australis initially decomposed more slowly (37–63% remaining) than those of S. alterniflora (23–53 % remaining), but after two years, decay was comparable (8–40% remaining for both species). Decomposition was slower at the RS site than at the other field sites, and it was slowest in the laboratory. Metal concentrations initially were lower in stems than in leaves, and Cr, Pb, and Zn were lower in P. australis than in S. alterniflora. In the field, large increases (10- to 100-fold) in metal concentrations rapidly obliterated any initial differences between plant species. Metal concentrations in leaves rose more quickly and remained greater than in stems. For example, Cu approached 300 μg/g in leaves but was less than 200 μg/g in stems. In contrast to the modest rise in metal concentrations in the leaf tissue at the more contaminated RS site (Zn rose to ∼200 μg/g in sediments containing ∼400 μg/g), Cu and Zn concentrations in leaf litter at the P and NS sites increased to levels exceeding those in the surrounding sediment (Zn rose to ∼500 μg/g in sediments containing ∼200 μg/g). Temporal changes in metal pools (grams of metal per litterbag) were not discernable because of the negative correlation of mass remaining and metal concentrations as well as because of the great variability of metal concentrations within each treatment. Decomposition and the accumulation of metals may be influenced more by differences between tissue types than by species or sediment metal concentrations.
Comparative analysis of estrogenic activity in sewage treatment plant effluents involving three in vitro assays and chemical analysis of steroids
Authors: Rutishauser Barbara V. , Pesonen Maija , Escher Beate I. , Ackermann Gabriele E. , Aerni Hans-Rudolf , Suter Marc J.-F. , Eggen Rik I.L.
Published: November 2004

In this study, we assessed and compared the suitability of three in vitro screening tools for the measurement of estrogenic activity in sewage treatment plant effluents (STPEs). These assays were the yeast estrogen screen (YES), production of zona radiata proteins (ZRPs) in trout hepatocytes, and the induction of reporter gene expression in the transfected rainbow trout gonad cell line RTG-2. Data obtained with the YES were additionally compared with calculated estrogenicity, based on steroid analysis data of the effluents. For comparison purposes, the response of the in vitro systems toward the estrogenic chemicals β-estradiol, ethinyl estradiol, bisphenol—A, nonylphenol, and octylphenol was assessed. All three assays showed sensitivities in the same order of magnitude in response to the steroid compounds tested, with ZRP production being the least sensitive. Regarding the estrogenic environmental chemicals tested, the RTG-2 assay was more than an order of magnitude more sensitive than the other two assays. Despite their different sensitivities toward selected test chemicals, the three in vitro systems indicated estrogenic activity in the same concentration range for the tested STPEs. Calculated estrogenicity (chemical analysis) and measured estrogenicity (YES) were of the same order of magnitude for the STPEs tested. The present study indicates that all three in vitro systems, with the yeast-based system being the easiest and most robust, are applicable for the screening of estrogenic activity in effluent samples.
Toxicity of simple mixtures to the nematode Caenorhabditis elegans in relation to soil sorption
Authors: Jonker Martijs J. , Sweijen Roland A.J.C. , Kammenga Jan E.
Published: November 2004

Single and combined toxicity of copper-zinc, copper—cadmium, cadmium—lead, copper—carbendazim, and copper-carbendazimiprodione to the nematode Caenorhabditis elegans in soil was studied. The one-week population increase was estimated as the toxicity endpoint. The aim was to study the relationship between mixture interactions in the soil and the combined toxic effect. Soil sorption was quantified using the Freundlich adsorption constant. Joint toxicity patterns were quantified by comparing mixture effects to the effect of individual constituents and were related to total metal concentrations in the soil, water-soluble concentrations, and 0.01 M CaCl2-extractable concentrations. The metal with the highest adsorption constant influenced the sorption of metal with the lowest adsorption constant when both were combined, indicating interaction. Consequently, both the composition of the mixture as well as the relative toxicity of individual mixture constituents differed between total, water-soluble, and CaCl2-extractable concentrations, which was taken into account in the data quantification procedure that was applied. Both the additive and the independent model were generally inadequate to describe the effects of metal mixtures. Compared to the additive model, synergism was observed at dose levels higher than the median effect isobole. A general relationship between mixture interactions in the soil and the combined toxicity was not found.
A food chain model to predict the levels of lipophilic organic contaminants in humans
Authors: Czub Gertje , McLachlan Michael S.
Published: November 2004

A fugacity-based, nonsteady state, mechanistic model called ACC-HUMAN was developed to describe bioaccumulation of lipophilic organic pollutants from air, water, and soil to humans. The physical environment was linked via a marine and an agricultural food chain model to a human bioaccumulation model. Contaminant uptake via the primary dietary sources of persistent lipophilic contaminants in industrialized countries was addressed, namely fish, dairy products, and beef. In addition, uptake from air and water was considered, allowing the model also to treat less lipophilic compounds. To evaluate the model, the food chain characteristics were parameterized for southern Sweden and historical scenarios of polychlorinated biphenyl (PCB) concentrations in air, water, and soil in this region were constructed from published data. The resulting model predictions of PCB concentrations in fish, milk, beef, and human tissue agreed well with measured concentrations from Swedish monitoring programs. This suggests that ACC-HUMAN is a useful tool for predicting human exposure to bioaccumulative organic compounds. It can be linked easily to existing multimedia fate and transport models.
Hydrolysis and photolysis of paroxetine, a selective serotonin reuptake inhibitor, in aqueous solutions
Authors: Kwon Jeong-Wook , Armbrust Kevin L.
Published: November 2004

The hydrolysis and photolysis of paroxetine HCl, a selective serotonin reuptake inhibitor, in aqueous buffer solutions (pH 5, 7, and 9), in synthetic humic water, and in lake water were investigated at 25°C in the dark and in a growth chamber outfitted with fluorescent lamps simulating the ultraviolet (UV) output of sunlight. Paroxetine was degraded completely within 4 d by simulated sunlight in all aqueous media. Photolysis of paroxetine HCl was accelerated by increasing pH. The t1/2 values at pH 5, 7, and 9 were 15.79, 13.11, and 11.35 h, respectively. The half-lives of paroxetine in synthetic humic water and two lake waters were slightly longer than in pH 7 buffer. Two photoproducts were detected and their structures were identified by liquid chromatography-mass spectrometry in positive mode. Photoproduct I was found to be photolytically unstable, being gradually degraded after 12 to 18 h of irradiation. However, photoproduct II was photolytically very stable throughout the experiment period, indicating that it was persistent to further photodegradation. In the dark, paroxetine in all aqueous solutions was found to be stable over a 30-d period. In conclusion, paroxetine is a relatively photolabile drug that has a possibility of photodegradation by sunlight in surface water.
Effect of sedimentary cadmium on the behavior of a burrowing mayfly (Ephemeroptera, Hexagenia limbata)
Authors: Gosselin Anne , Hare Landis
Published: November 2004

Behavioral responses of aquatic invertebrates can serve as precocious indicators of adverse effects caused by metals. We conducted experiments to determine if the behavior of nymphs of the burrowing mayfly Hexagenia limbata (Ephemeroptera) was modified by the presence of cadmium (Cd) in sediments. We first exposed H. limbata to concentrations of sedimentary Cd found in lakes subject to smelter emissions (20 μg/g dry wt). We then compared the burrowing activity of control and Cd-contaminated nymphs by means of radiographs. We also studied the time allotted by nymphs to various activities (irrigation, walking, burrowing/ feeding, cleaning, and turning) as determined from films taken using an infrared video camera. The results obtained suggest no significant difference in the burrowing activity of control versus Cd-contaminated individuals. Furthermore, the time spent in various behavioral activities was similar between control and Cd-contaminated nymphs. Given these results, we conclude that Cd has no effect on the behavior of H. limbata for the range of Cd concentrations that we measured in nymphs.
Blarina brevicauda as a biological monitor of polychlorinated biphenyls: Evaluation of hepatic cytochrome P450 induction
Authors: Russell Julie S. , Halbrook Richard S. , Woolf Alan , French John B. , Melancon Mark J.
Published: November 2004

We assessed the value of short-tailed shrews (Blarina brevicauda) as a possible biomonitor for polychlorinated biphenyl pollution through measurement of the induction of hepatic cytochrome P450 and associated enzyme activities. First, we checked the inducibility of four monooxygenases (benzyloxyresorufin-O-dealkylase [BROD], ethoxyresorufin-O-dealkylase [EROD], methoxyresorufin-O-dealkylase [MROD], and pentoxyresorufin-O-dealkylase [PROD]) by measuring the activity of these enzymes in hepatic microsomes prepared from shrews injected with β-naphthoflavone (βNF) or phenobarbital (PB), typical inducers of cytochrome P4501A (CYP1A) and CYP2B enzyme families, respectively. Enzyme activity was induced in shrews that received βNF but not in shrews that received PB; PROD was not induced by either exposure. Later, shrews were exposed to a mixture of polychlorinated biphenyls (PCBs) (Aroclor 1242:1254, in 1:2 ratio) at 0.6, 9.6, and 150 ppm in food, for 31 d. Induction in these shrews was measured by specific enzyme activity (BROD, EROD, and MROD) in hepatic microsomes, by western blotting of solubilized microsomes against antibodies to CYP1A or CYP2B, and by duration of sodium pentobarbital-induced sleep. These three CYP enzymes were induced in shrews by PCBs at similar levels of exposure as in cotton rat (Sigmodon hispidus). Neither sleep time nor the amount of CYP2B family protein were affected by PCB exposure. Blarina brevicauda can be a useful biomonitor of PCBs that induce CYP1A, especially in habitats where they are the abundant small mammal.
Mysid crustaceans as potential test organisms for the evaluation of environmental endocrine disruption: A review
Authors: Verslycke Tim A. , Fockedey Nancy , McKenney Charles L. , Roast Stephen D. , Jones Malcolm B. , Mees Jan , Janssen Colin R.
Published: November 2004

Anthropogenic chemicals that disrupt the hormonal systems (endocrine disruptors) of wildlife species recently have become a widely investigated and politically charged issue. Invertebrates account for roughly 95% of all animals, yet surprisingly little effort has been made to understand their value in signaling potential environmental endocrine disruption. This omission largely can be attributed to the high diversity of invertebrates and the shortage of fundamental knowledge of their endocrine systems. Insects and crustaceans are exceptions and, as such, appear to be excellent candidates for evaluating the environmental consequences of chemically induced endocrine disruption. Mysid shrimp (Crustacea: Mysidacea) may serve as a viable surrogate for many crustaceans and have been put forward as suitable test organisms for the evaluation of endocrine disruption by several researchers and regulatory bodies (e.g., the U.S. Environmental Protection Agency). Despite the long-standing use of mysids in toxicity testing, little information exists on their endocrinology, and few studies have focused on the potential of these animals for evaluating the effects of hormone-disrupting compounds. Therefore, the question remains as to whether the current standardized mysid endpoints can be used or adapted to detect endocrine disruption, or if new procedures must be developed, specifically directed at evaluating hormone-regulated endpoints in these animals. This review summarizes the ecological importance of mysids in estuarine and marine ecosystems, their use in toxicity testing and environmental monitoring, and their endocrinology and important hormone-regulated processes to highlight their potential use in assessing environmental endocrine disruption.
Modeling the fate of polychlorinated biphenyls in the inner Oslofjord, Norway
Authors: Breivik Knut , Bjerkeng Birger , Wania Frank , Helland Aud , Magnusson Jan
Published: November 2004

A dynamic, segmented, multimedia fate and transport model has been developed, evaluated, and applied to gain insight regarding the behavior of seven polychlorinated biphenyl (PCB) congeners in the Inner Oslofjord (Norway). A comparison with a dated sediment core reveals that the model is not capable of reproducing some key features of the observed, historical, long-term trend in sediments, although better agreement is observed for six of seven PCB congeners over the last two decades. The model also underestimates the concentrations of PCBs in surface sediments in areas adjacent to the city of Oslo (Norway). In general, deviations between modeled and observed concentrations indicate that the historical emissions and discharges of PCBs are not sufficiently characterized and described. Net fluxes predicted by the model suggest that several congeners may have experienced a reversal of air-water and seawater-sediment exchange during the last decade or even earlier. The present study further suggests that the benefit of the proposed removal of the most contaminated sediments of the Inner Oslofjord needs to be assessed, with consideration of the relative contribution of current atmospheric inputs as well as the leaching of PCBs from less contaminated sediments.
Model verification of thermal programmed desorption-mass spectrometry for estimation of release energy values for polycyclic aromatic hydrocarbons on mineral sorbents
Authors: Nicholl Sara I. , Talley Jeffrey W. , Silliman Stephan
Published: November 2004

The physical availability of organic compounds in soil and sediment strongly influences their bioavailability and toxicity. Previous work has indicated that physical availability changes throughout the processes of aging and treatment and that it can be linked to the energy required to release the compound from its sorbent matrix, with a higher energy indicating a more tightly bound compound. This study focused on determining release energy values for various mineral geosorbents (glass beads, sand, and kaolin) contaminated with a 16 polycyclic aromatic hydrocarbon (PAH) mixture. The sorbents were analyzed using thermal program desorption/mass spectrometry (TPD/MS) and the release energy values were calculated from the resulting thermograms utilizing a nonlinear fit of the analytical solution to a simplified version of the Polanyi-Wigner equation. This solution method resulted in a series of combinations of values for the pre-exponential factor (v) and release energy (E) that produced desorption rate curves with similar errors when fit to actual data sets. These combinations can be viewed as an error surface, which clearly shows a valley of minimum error values spanning the range of both E and v. This indicates that this method may not provide a unique set of E- and v-values and suggests that the simplified version of the Polanyi-Wigner equation cannot be used to determine release energy based on TPD data alone.
Digestive bioavailability to a deposit feeder (Arenicola marina) of polycyclic aromatic hydrocarbons associated with anthropogenic particles
Authors: Voparil Ian M. , Burgess Robert M. , Mayer Lawrence M. , Tien Rex , Cantwell Mark G. , Ryba Stephen A.
Published: November 2004

Marine sediments around urban areas serve as catch basins for anthropogenic particles containing polycyclic aromatic hydrocarbons (PAHs). Using incubations with gut fluids extracted from a deposit-feeding polychaete (Arenicola marina), we determined the digestive bioavailability of PAHs from fly ashes, coal dusts, diesel soots, tire tread materials, and urban particulates. We found that gut fluids solubilize significant concentrations of PAHs from two tire treads, two diesel soots, and the urban particulates. However, PAHs in fly ashes and coal dusts were not available to the digestive agents in gut fluid. Potential digestive exposure to PAHs is much greater than that predicted to be available from these materials using equilibrium partitioning theory (EqP). Amending an already-contaminated sediment with fly ash decreased phenanthrene solubilization by gut fluid. In contrast, addition of tire tread to the sediment resulted in increased solubilization of four PAHs by gut fluid. Therefore, addition of certain types of anthropogenic particles to sediments may result in an increase in bioavailable PAHs rather than a net decrease, as predicted by EqP. Difficulty in predicting the amount of change due to amendment may be due to interactions occurring among the mixture of compounds solubilized by gut fluid.
Evaluation of the role of black carbon in attenuating bioaccumulation of polycyclic aromatic hydrocarbons from field-contaminated sediments
Authors: Sundelin Brita , Wiklund Ann-Kristin Eriksson , Lithner Göran , Gustafsson Örjan
Published: November 2004

The significance of black carbon (BC) for the bioavailability of polycyclic aromatic hydrocarbons (PAHs) was examined by using historically contaminated intact sediment cores in laboratory exposure experiments with the deposit-feeding amphipod Monoporeia affinis. Log values of amphipod biota–sediment accumulation factors (BSAFs) were significantly related to log BC, whereas log BSAFs were related to log octanol–water partition coefficients only in background sediments containing less BC. In the background sediments, the BSAF for polycyclic aromatic hydrocarbons (PAHs) was 1 to 2 for phenanthrene, with lower values for more hydrophobic PAHs, indicating an increase in nonequilibrium conditions with increasing PAH molecular size. For the near-equilibrated phenanthrene and fluoranthene, higher BSAFs were measured during exposure to background sediments, with BSAF decreasing to <0.1 in contaminated sediments in the Stockholm waterways. In situ caged mussels (Dreissena polymorpha) exhibited field BSAF values (relative to sediment-trap–collected suspended matter) for polychlorinated biphenyls (PCBs) of 0.1 to 0.4, but for PAHs of similar hydrophobicity and molecular size, the field BSAFs were much lower and in the range 0.002 to 0.05. This PAH–PCB dichotomy is consistent with recently reported much stronger binding to diesel soot (a form of BC) for PAHs than for PCBs of equal hydrophobicities. Lower BSAFs for the near-equilibrated PAHs (phenanthrene and fluoranthene) in the urban sediments relative to the background sediments were consistent with the larger presence of BC in the urban sediments. This study provides the first linked BSAF–BC field data that supports a causal relationship between strong soot sorption and reduced bioavailability for PAHs.
Comparison of accumulation of micropollutants between indigenous and transplanted zebra mussels (Dreissena polymorpha)
Authors: Bervoets Lieven , Voets Judith , Chu Shaogang , Covaci Adrian , Schepens Paul , Blust Ronny
Published: November 2004

Zebra mussels (Dreissena polymorpha) were exposed at 12 canals and lakes situated in Flanders (Belgium), in cages for six weeks during the summer of 2002. Accumulation of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexachlorobenzene, and trace metals were measured in the transplanted mussels and levels compared to levels in indigenous mussels. Additionally, zebra mussels were exposed at a small lake in the vicinity of Antwerp (Belgium), and accumulation of contaminants was followed for an extended period from December 2001 to April 2002. Analysis of the pollutants in the indigenous mussels showed that the selected sites displayed a wide range of pollution from near to background to very high levels of metals and/or organic contaminants when compared to the literature. For organic contaminants and for most metals, comparison of levels between caged and resident mussels revealed no significant differences. Only for cadmium and nickel, significant differences were observed, with levels being either higher (cadmium) or lower (nickel) in caged mussels. For organic contaminants, significant correlations between levels in caged and resident mussels were found with r2 values up to 0.98. For some metals, no or poor correlations were found. At most sites, concentrations of those metals were of the same order of magnitude and comparable to levels in mussels from unpolluted sites. This might explain the absence of significant correlations. When mussels were exposed for an extended period, the concentration of some pollutants increased, whereas others decreased with time. Only in the case of certain metals did levels differ significantly because of the slow depuration of metals already present in the transplanted mussels. This is an additional indication that measured concentrations in transplanted mussels indeed reflected the local situation. With this study, we were able to prove the applicability of transplanted mussels as a biomonitoring tool for the accumulation of pollutants over a wide range of pollution.
Accumulation and distribution of polychlorinated dibenzo-p-dioxin, dibenzofuran, and polychlorinated biphenyl congeners in atlantic salmon (Salmo salar)
Authors: Isosaari Pirjo , Kiviranta Hannu , Lie Øyvind , Lundebye Anne-Katrine , Ritchie Gordon , Vartiainen Terttu
Published: November 2004

Adult Atlantic salmon (Salmo salar) were fed on four diets containing polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) for 30 weeks. Lipid-normalized concentrations showed that all congeners were equally partitioned between whole-fish and fillet samples. Skinned fillet accumulated approximately 30% of the total PCDD/F and PCB content in fish. Accumulation efficiencies in whole fish were 43% for 2,3,7,8-chlorinated dibenzo-p-dioxins and dibenzofurans, 83% for dioxin-like PCBs, and 78% for other PCB congeners. Among PCDD/Fs, tetra- and pentachlorinated congeners were preferentially accumulated in salmon, whereas hepta- and octachlorinated dibenzo-p-dioxins were excreted in the feces. Substitution patterns that were associated with a preferential accumulation of PCBs in salmon included non-ortho substitution and tetrachlorination. Accumulation efficiencies and lipid-normalized biomagnification factors (BMFs) were not influenced by the PCDD/F and PCB concentrations of the diets. Biomagnification (BMF > 1) of tetra- and pentachlorinated dibenzo-p-dioxins and dibenzofurans and of all the PCBs was observed. Differences in the behavior of PCDD/F and PCB congeners resulted in a selective enrichment of the most toxic congeners in salmon.
Morphological responses of Daphnia pulex to Chaoborus americanus kairomone in the presence and absence of metals
Authors: Hunter Kim , Pyle Greg
Published: November 2004

Daphnia pulex neonates develop neck teeth in the presence of predatory kairomone from Chaoborus americanus that are fed D. pulex. These neck teeth reduce the susceptibility of the neonates to predation. Evidence suggests that aqueous metals interfere with chemical communication in fish. The objective of our study was to determine if Cu or Ni at environmentally relevant concentrations affects predatory kairomone response in D. pulex. To test this possibility, D. pulex were placed in increasing waterborne concentrations of Cu or Ni in the presence or absence of predatory kairomone. Both Cu and Ni reduced neck tooth induction in D. pulex neonates in the presence of predatory kairomone. Copper had a significant nonlinear effect on neck tooth length consistent with a hormetic response, where neck tooth length was highest at 5 μg/L Cu, but not significantly different than 0 μg/L Cu at higher Cu concentrations. A Ni concentration of 200 μg/L caused D. pulex to become hypersensitive to Chaoborus regardless of Chaoborus' diet, leading to increased neck tooth number but decreased neck tooth length. Neither Ni nor Cu produced any significant effects on body length or brood size. These results suggest that metal inhibition of neck tooth induction probably occurs along the signal transduction pathway. Impairment of chemosensory response to predatory chemical cues may have widespread ecological consequences in aquatic systems contaminated by metals.
Fate of veterinary antibiotics in a macroporous tile drained clay soil
Authors: Kay Paul , Blackwell Paul A. , Boxall Alistair B. A.
Published: November 2004

The environment may be exposed to veterinary medicines administered to livestock through the application of organic fertilizers to land. For other groups of substances that are applied to agricultural land (e.g., pesticides), preferential flow in under-drained clay soils has been identified as an extremely important mechanism by which pollution of surface waters can occur. This study, therefore, was performed to investigate the fate of three antibiotics from the sulfonamide, tetracycline, and macrolide groups. Pig slurry was applied to a field in arable production in two consecutive years and the fate of the compounds was monitored in the soil and drainage water. Both sulfachloropyridazine and oxytetracycline were detected in soil at concentrations up to 365 and 1691 μg/kg, respectively. Subsequently, peak concentrations of the two substances in drainflow were 613.2 and 36.1 μg/L, although mass losses to the receiving water were less than 0.5%. In contrast, tylosin was not detected at all. These findings could be explained by the persistence and sorption characteristics of the antibiotics, while preferential flow via desiccation cracks and worm channels to the tile drains was found to be the most important route for translocation of the chemicals. Thus, when the soil was disced prior to slurry application, losses were reduced significantly. It is evident that processes governing pesticide fate also apply to veterinary antibiotics.
Influence of multigeneration acclimation to copper on tolerance, energy reserves, and homeostasis of Daphnia magna Straus
Authors: Bossuyt Bart T. A. , Janssen Colin R.
Published: November 2004

A multigeneration acclimation experiment was performed with Daphnia magna exposed to copper to assess possible changes in tolerance and to establish the optimal concentration range (OCEE) of this species. The hypothesis was tested that as the bioavailable background concentration of an essential metal increases (within realistic limits), the natural tolerance (to the metal) of the acclimated/adapted organisms and communities will increase. During 18 months the daphnids were exposed to six different, environmentally relevant, copper background concentrations ranging between 0.5 and 100 μg Cu L−1 (7 × 10−15 and 3.7 × 10−9 M Cu2+). An increase in acute (effect concentration resulting in 50% immobility: 48-h EC50) and chronic copper (effect concentration resulting in 50% or 10% reproduction reduction: 21-d EC50, 21-d EC10) tolerance was observed with increasing exposure concentration. The 48-h EC50 increased significantly from 204 ± 24 μg Cu L−1 to 320 ± 43 μg Cu L−1. A nonsignificant change from 48.0 (47.9–48.0) μg Cu L−1 to 78.8 (66.3–93.6) μg Cu L−1 was noted in the chronic toxicity assays. The optimal concentration range was assessed using different biological parameters (i.e., net reproduction [R0]), energy reserves (Ea), body length measurements, filtration rates, and body burdens. After three generations of acclimation the OCEE ranged between 1 and 35 μg Cu L−1 (2 × 10−14 to 80 × 10−12 M Cu2+). Body burden measurements revealed an active copper regulation up to 35 μg Cu L−1 (80 pM Cu2+). It can be concluded that acclimation of D. magna to copper does occur in laboratory experiments, even at realistic copper background concentrations (10−11– 10−9 M Cu2+). However, it is suggested that this phenomenon is of less importance in the context of regulatory risk assessments. An optimal copper concentration range for D. magna was observed between 1 and 35 μg Cu L−1 (10−14 −10−11 M Cu2+), indicating that copper deficiency can occur in routine laboratory cultures.
Acute and chronic toxicity of nickel to rainbow trout (Oncorhynchus mykiss)
Authors: Brix Kevin V. , Keithly James , DeForest David K. , Laughlin Jim
Published: November 2004

Of the fish species tested in chronic Ni exposures, rainbow trout (Oncorhynchus mykiss) is the most sensitive. To develop additional Ni toxicity data and to investigate the toxic mode of action for Ni, we conducted acute (96-h) and chronic (85-d early life-stage) flow-through studies using rainbow trout. In addition to standard toxicological endpoints, we investigated the effects of Ni on ionoregulatory physiology (Na, Ca, and Mg). The acute median lethal concentration for Ni was 20.8 mg/L, and the 24-h gill median lethal accumulation was 666 nmol/g wet weight. No effects on plasma Ca, Mg, or Na were observed during acute exposure. In the chronic study, no significant effects on embryo survival, swim-up, hatching, or fingerling survival or growth were observed at dissolved Ni concentrations up to 466 μg/L, the highest concentration tested. This concentration is considerably higher than the only other reported chronic no-observed-effect concentration (<33 μg/L) for rainbow trout. Accumulation of Ni in trout eggs indicates the chorion is only a partial barrier with 36%, 63%, and 1% of total accumulated Ni associated with the chorion, yolk, and embryo, respectively. Whole-egg ion concentrations were reduced by Ni exposure. However, most of this reduction occurred in the chorion rather than in the embryos, and no effects on hatching success or larval survival were observed as a result. Plasma ion concentrations measured in swim-up fingerlings at the end of the chronic-exposure period were not significantly reduced by exposure to Ni. Nickel accumulated on the gill in an exponential manner but plateaued in trout plasma at waterborne Ni concentrations of 118 μg/L or greater. Consistent with previous studies, Ni did not appear to disrupt ionoregulation in acute exposures of rainbow trout. Our results also suggest that Ni is not an ionoregulatory toxicant in long-term exposures, but the lack of effects in the highest Ni treatment precludes a definitive conclusion.
Runoff simulation with particle-associated azinphosmethyl in multispecies stream microcosms: Implications for the field
Authors: Thiere Geraldine , Schulz Ralf
Published: November 2004

We investigated the acute (5 d) effects of particle-associated azinphosmethyl (AZP) in multispecies microcosms and assessed the results in the context to data obtained from a parallel field study undertaken in the Lourens River, South Africa. A runoff simulation was carried out in stream microcosms containing the macroinvertebrate fauna of an uncontaminated Lourens River site exposed to particle-associated AZP (control and 200, 1,000, 5,000, 20,000 μg/kg; three replicates each) for 1 h. Measured AZP concentrations in filtered microcosm water resulted in the following values: Not detectable (control) and 0.03, 0.2, 1.1, and 6.9 μg/L, respectively. The two highest treatments resulted in significantly (analysis of variance [ANOVA]) reduced total numbers of individuals, while the number of taxa was affected in the 20,000 μg/kg treatment only. A comparison with previous data suggests that observed effects partly resulted from particle-associated AZP. Particularly affected were six out of 14 macroinvertebrate taxa such as mayfly and stonefly taxa. In parallel, the distribution of macroinvertebrates at a pesticide-free and a contaminated stretch of the Lourens River was monitored five times during the spraying season in 2001 and 2002. Out of the 14 core taxa found in the microcosm study as well as in the field approach, 10 showed comparable reactions in the microcosm experiment and in their field distribution; they were either classified as affected or unaffected in both studies. Thus, we conclude that particle-associated AZP has the potential to affect the invertebrate community structure of the Lourens River and that microcosm studies employing fieldrelevant exposure scenarios may be valuable for a local risk assessment of pesticide-related community disruptions in the Lourens River.
Obtaining quantitative vapor emissions estimates of polychlorinated biphenyls and other semivolatile organic compounds from contaminated sites
Authors: Mills William J. , Bennett Erin R. , Schmidt Charles E. , Thibodeaux Louis J.
Published: November 2004

Soils contaminated with polychlorinated biphenyls (PCBs) and other semivolatile organic compounds (SVOs) represent a potentially major, ongoing source of these compounds to the environment, especially during warmer temperatures. A great deal of work has been devoted to understanding the mechanisms that govern the vaporization of SVOCs from soil, but to date, few quantitative estimates have been published regarding emissions from contaminated sites. The present paper describes methods for obtaining quantitative estimates of SVOCs from soils based on flux chamber measurements, modeling, and ambient air measurements. On wet (i.e., H2O) soils, SVOCs at very low chemical loading levels on the adsorption sites (the so-called critical chemical concentration, critical loading, or saturation concentration) will behave, for volatilization purposes, as the pure-liquid substance would. For one soil, the PCB critical concentration was determined to be 775 ppm (95% confidence interval, 5.40E+02). Flux chamber-measured emissions from two contaminated sites were used and compared to model estimated values. The results agree reasonably well and indicate that the modeling approach used provided a conservative upper bound on the emissions. These approaches can be used to develop emissions estimates for SVOC-contaminated sites and inputs to air dispersion models.
Multimedia persistence as an indicator of potential for population-level intake of environmental contaminants
Authors: MacLeod Matthew , McKone Thomas E.
Published: November 2004

Although intuitively it is apparent that population-level exposure to contaminants dispersed in the environment must be related to the persistence of the contaminant, there has been little effort to quantify this link formally. In this paper we investigate the relationship between overall persistence and/or overall residence time in a multimedia exposure environment and the population-level intake of contaminants as expressed by intake fraction (iF), the cumulative fraction of chemical emitted to the environment that is taken up by members of the population. We demonstrate that for any given contaminant and emission scenario the definition of iF implies that it is directly proportional to the overall multimedia persistence (POV), or the overall multimedia residence time (TOV). The proportionality constant has dimensions of time and represents the characteristic time for population intake (CTI) of the chemical from the environment. We then apply the CalTOX fate and exposure model to explore how TOV and CTI combine to determine the magnitude of iF. We find that CTI has a narrow range of possible values relative to TOV across multiple chemicals and emissions scenarios. We use data from the Canadian Environmental Protection Act Priority Substance List (PSL1) Assessments and multimedia POV to show that exposure assessments based on empirical observation are consistent with interpretations from the model. Results indicate that POV derived from screening-level assessments of persistence, bioaccumulation potential, and toxicity (PBT) is a useful indicator of the potential for population-level exposure.
Investigating the mechanics of multimedia box models: How to explain differences between models in terms of mass fluxes?
Authors: Scheringer Martin , Wegmann Fabio , Hungerbühler Konrad
Published: November 2004

The simple mathematical structure of multimedia fate models makes it possible to change the process descriptions and geometry of such models relatively easily. With different versions of a model, the effect of a process or compartment that is included in one version of the model but excluded in another version can be investigated. Here, a new method for performing such a model comparison in a quantitative way is presented. Based on the mass balances for the two model versions, it can be shown that, for a compartment contained in both model versions, the difference between a chemical's concentrations in this compartment is related directly to the difference in those mass fluxes that have different rate constants in the two models. Moreover, it is possible to identify the contributions to the concentration difference that stem from individual mass fluxes so that the concentration difference can be tracked back to specific differences in the process descriptions of the two models. This flux analysis method is illustrated with two versions of a unit-world model, one with and one without a vegetation compartment. With DDT and six polychlorinated biphenyl (PCB) congeners as example chemicals, the differences of the chemicals' concentrations in air and soil caused by the vegetation compartment are explained by using the flux analysis method. The future potential of the method for comparing not only versions of the same model but also models of different structure is discussed.
Dependency of polychlorinated biphenyl and polycyclic aromatic hydrocarbon bioaccumulation in Mya arenaria on both water column and sediment bed chemical activities
Authors: Lohmann Rainer , Burgess Robert M. , Cantwell Mark G. , Ryba Steven A. , MacFarlane John K. , Gschwend Philip M.
Published: November 2004

The bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) by the filter-feeding soft-shell clam Mya arenaria was evaluated at three sites near Boston (MA, USA) by assessing the chemical activities of those hydrophobic organic compounds (HOCs) in the sediment bed, water column, and organisms. Polyethylene samplers were deployed to measure the activities of HOCs in the water column. Sediment activities were assessed by normalizing concentrations with sediment-water sorption coefficient values, including adsorption to black carbon in addition to absorption by organic carbon. Likewise, both lipids and proteins were considered in biota-water partition coefficients used to estimate chemical activities in the animals. Chemical activities of PAHs in M. arenaria were substantially less than those of the corresponding bed sediments in which they lived. In contrast, chemical activities of PCBs in M. arenaria often were greater than or equal to activities in the corresponding bed sediments. Activities of PAHs, such those of pyrene, in the water column were undersaturated relative to the sediment. However, some PCBs, such as congener 52, had higher activities in the water column than in the sediment. Tissue activities of pyrene generally were in between the sediment and water column activities, whereas activity of PCB congener 52 was nearest to water column activities. These results suggest that attempts to estimate bioaccumulation by benthic organisms should include interactions with both the bed sediment and the water column.
Sediments are major sinks of steroidal estrogens in two United Kingdom rivers
Authors: Peck Mika , Gibson Richard W. , Kortenkamp Andreas , Hill Elizabeth M.
Published: November 2004

The occurrence of intersex fish in a number of European rivers has been attributed to exposure to estrogenic chemicals present in sewage treatment work (STW) effluents. To further understand the environmental fate of these contaminants, the estrogenic activity of effluents, water, and sediments were investigated both upstream and downstream of the major STW discharge in two United Kingdom rivers. Estrogenic activity, determined using the yeast estrogen-receptor transcription screen, of the major STW effluents on both rivers was similar, ranging from 1.4 to 2.9 ng 17β-estradiol equivalents (EEQ)/L. Estrogenic activities of surface waters 1 km upstream and downstream of both STW inputs were less than the limits of detection (0.04 ng/L); however, levels of estrogenic activity in sediments were between 21.3 and 29.9 ng EEQ/kg and were similar at both upstream and downstream sites. Effluent and sediment extracts were fractionated by reverse phase-high-performance liquid chromatography, and estrogenic active fractions were further analyzed by gas chromatography-mass spectrometry. The major active chemicals in the two effluents and in the sediments were estrone with lesser amounts of 17β-estradiol; however, at one site, a number of other unidentified estrogenic fractions were detected in the sediments. These results suggest that riverine sediments are a major sink and a potential source of persistent estrogenic contaminants.
Effects of chronic dietary copper exposure on growth and reproduction of Daphnia magna
Authors: De Schamphelaere Karel A. C. , Janssen Colin R.
Published: November 2004

A matter of current, intense debate with regard to the effects of metals on biological systems is the potential toxicity of metals associated with food particles. Recently developed biotic ligand models (BLM), which predict the toxicity of waterborne metals, may not be valid if the dietary exposure route contributes to metal toxicity. The present study is, to our knowledge, the first that investigates the potential toxicity of dietary copper to a freshwater invertebrate (i.e., Daphnia magna) feeding on a live diet (i.e., the green alga Pseudokircheneriella subcapitata). Algae were exposed for 3 d to different copper concentrations, resulting in algal copper burdens between approximately 6.2 × 10−16 and 250 × 10−16 g cell−1. These algae were then used as food in chronic, 21-d D. magna toxicity tests in which growth, reproduction, and copper accumulation were assessed. Three exposure scenarios were tested: A waterborne exposure, a dietary exposure, and a combined waterborne and dietary exposure. Although exposure to dietary copper resulted in an increased copper body burden of the adult daphnids, it did not contribute to toxicity and did not affect the 21-d effect concentrations expressed as waterborne copper, indicating that the previously established good predictive capacity of the chronic D. magna BLM is not affected. On the contrary, exposure to the highest dietary copper levels resulted in an increase of as much as 75% in growth and reproduction. To our knowledge, this is the first evidence that dietary copper exposure of a freshwater invertebrate feeding on a live diet resulted in a beneficial effect.