Assessment of cytotoxicity and AhR-mediated toxicity in tropical fresh water sediments under the influence of an oil refinery

Oil refinery effluents contain many chemicals at variable concentrations. Therefore, it is difficult to predict potential effects on the environment. The Atibaia River (SP, Brazil), which serves as a source of water supply for many municipalities, receives the effluents of one of the biggest oil refinery of this country. The aim of this study was to identify the (eco)toxicity of fresh water sediments under the influence of this oil refinery through neutral red (cytotoxicity) and ethoxyresorufin-O-deethylase (EROD) assays (AhR-mediated toxicity) in RTL-W1 cells (derived from fish liver). Once the refinery captures the waters of Jaguarí River for the development of its activities and discharges its effluents after treatment into the Atibaia River, which then flows into Piracicaba River, sediments from both river systems were also investigated. The samples showed a high cytotoxic potential, even when compared to well-known pollution sites. However, the cytotoxicity of samples collected downstream the effluent was not higher than that of sediments collected upstream, which suggested that the refinery discharges are not the main source of pollution in those areas. No EROD activity could be recorded, which could be confirmed by chemical analyses of polycyclic aromatic hydrocarbons (PAHs) that revealed a high concentration of phenanthrene, anthracene, fluoranthene, and pyrene, which are not EROD inducers in RTL-W1 cells. In contrast, high concentrations of PAHs were found upstream the refinery effluent, corroborating cytotoxicity results from the neutral red assay. A decrease of PAHs was recorded from upstream to downstream the refinery effluent, probably due to dilution of compounds following water discharges. On the other hand, these discharges apparently contribute specifically to the amount of anthracene in the river, since an increase of anthracene concentrations could be recorded downstream the effluent. Since the extrapolation of results from acute toxicity to specific toxic effects with different modes of action is a complex task, complementary bioassays covering additional specific effects should be applied in future studies for better understanding of the overall ecotoxicity of those environments.

Unexpected toxicity decrease during photoelectrochemical degradation of atrazine with NaCl

This report shows an unexpected toxicity decrease during atrazine photoelectrodegradation in the presence of NaCl. Atrazine is a pesticide classified as endocrine disruptor occurring in industrial effluents and agricultural wastewaters. We therefore studied the effects of the degradation method, electrochemical and electrochemical photo-assisted, and of the supporting electrolyte, NaCl and Na2SO4, on the residual toxicity of treated atrazine solutions. We also studied the toxicity of treated atrazine solutions using Results show that at initial concentration of 20 mg L-1, atrazine was completely removed in up to 30 min using 10 mA cm(-2) electrolysis in NaCl medium, regardless of the electrochemical method used. The total organic carbon removal by the photo-assisted method was 82% with NaCl and 95% with Na2SO4. The solution toxicity increased during sole electrochemical treatment in NaCl, as expected. However, the toxicity unexpectedly decreased using the photo-assisted method. This finding is a major discovery because electrochemical treatment with NaCl usually leads to the formation of toxic chlorine-containing organic degradation by-products.

Effects of atrazine and picloram on grass carp: acute toxicity and histological assessment

The aim of this study was to evaluate the acute toxicity of atrazine and picloram separately to grass carp (Ctenopharyngodon idella). Firstly, fingerlings were exposed to nominal concentrations of these herbicides to determine the lethal concentration (LC50) (96 h). After this, the animals were treated with sub-acute concentrations of the herbicides to measure the effects on gill histology. The LC50 (96 h) of the atrazine and picloram were, respectively, 37mg L-1 and 4.4 mgL(-1). Four types of alterations were found in gills exposed to atrazine, which were epithelial lifting, partial cell proliferation, lamellar fusion, and aneurysm. Nominal concentrations of picloram caused epithelial lifting, partial cell proliferation, and lamellar fusion.

Cadmium and Chromium Toxicity to Pseudokirchneriella subcapitata and Microcystis aeruginosa

The toxicity of cadmium and chromium to Pseudokirchneriella subcapitata and Microcystis aeruginosa was evaluated through algal growth rate during 96h exposure bioassays. Free metal ion concentrations were obtained using MINEQL(+) 4.61 and used for IC50 determination. Metal accumulations by the microorganisms were determined and they were found to be dependent on the concentration of Cd2+ and Cr6+. IC50 for P. subcapitata were 0.60 mu mol L-1 free Cd2+ and 20 mu mol L-1 free Cr6+, while the IC50 values for M. aeruginosa were 0.01 mu mol L-1 Cd2+ and 11.07 mu mol L-1 Cr6+. P. subcapitata accumulated higher metal concentrations (0.001 - 0.05 mu mol Cd mg(-1) dry wt. and 0.001 - 0.04 mu mol Cr mg(-1) dry wt) than the cyanobacteria (0.001 - 0.01 mu mol Cd mg(-1) dry wt and 0.001 - 0.02 mu mol Cr mg(-1) dry wt). Cadmium was more toxic than chromium to both the microorganisms.

Pharmaceutical residues in aquatic systems: mode of action and effects on mussel physiology

Pharmaceutical residues contaminate aquatic ecosystems as a result of their widespread human and veterinary usage. Since continuously released and not efficiently removed, certain pharmaceuticals exhibit pseudo-persistence thus generating concerns for the health of aquatic wildlife. This work aimed at assessing on mussels Mytilus galloprovincialis, under laboratory conditions, the effects of three pharmaceuticals, carbamazepine (antiepileptic), propranolol (β-blocker) and oxytetracycline (antibiotic), to evaluate if the human-based mode of action of these molecules is conserved in invertebrates. Furthermore, in the framework of the European MEECE Programme, mussels were exposed to oxytetracycline and copper at increasing temperatures, simulating variations due to climate changes. The effects of these compounds were assessed evaluating a battery of biomarkers, the expression of HSP70 proteins and changes in cAMP-related parameters. A decrease in lysosomal membrane stability, induction of oxidative stress, alterations of cAMP-dependent pathway and the induction of defense mechanisms were observed indicating the development of a stress syndrome, and a worsening in mussels health status. Data obtained in MEECE Programme confirmed that the toxicity of substances can be enhanced following changes in temperature. The alterations observed were obtained after exposure to pharmaceuticals at concentrations sometimes lower than those detected in the aquatic environment. Hence, further research is advisable regarding subtle effects of pharmaceuticals on non-target organisms. Furthermore, results obtained during a research stay in the laboratories of Cádiz University (Spain) are presented. The project aimed at measuring possible effects of polluted sediments in Algeciras Bay (Spain) and in Cádiz Bay, by assessing different physiological parameters in caged crabs Carcinus maenas and clams Ruditapes decussatus exposed in situ for 28 days. The neutral red retention assay was adapted to these species and proved to be a sensitive screening tool for the assessment of sediment quality.

Isolation and characterization of a manganese oxidizing bacterium from the Mediterranean marine sponge Suberites domuncula

In the present study of sponge-bacterial association, the presence of a marine bacterium which has not seen to be associated previously with the Mediterranean sponge Suberites domuncula was investigated. The marine sponge S. domuncula was chosen as the subject of investigation, for the identification of potential symbiotic microorganisms, since it can be kept under controlled laboratory conditions for over five years. By the use of specialized media assisting in the growth of a metal oxidizing bacterium, the manganese oxidizing bacterium was isolated from the surface of the marine sponge. The bacterium so isolated was characterized for its growth characteristics by microbiological and biochemical techniques, a detailed analysis of which showed that the bacterium followed a life cycle where the culture showed the presence of spore forming bacteria. This was correlated to the manganese oxidation activity of the bacteria and it was found that both stages are interdependent.The action of the protein responsible for carrying out the manganese (Mn) oxidation was studied by an in-gel oxidation assay, and the presence of a multi copper oxidase was confirmed by the use of copper chelators in the buffer. In parallel the effect of addition of copper was observed on the manganese oxidation by the bacteria thus supporting the observations. The manganese oxidation reaction by the bacteria was determined in the culture medium and on the surface of the cells, and it could be concluded that the oxidation was facilitated by the presence of the polysaccharides and proteins on the surface of the cells.Thus the presence of a bacterium capable of oxidizing the manganese from the surroundings was confirmed to be symbiotically associated with the marine sponge S. domuncula by monitoring its growth in axenic cultures. The reasons behind this association were studied.This bacterium displays a crucial role in the physiology/metabolism of the sponge by acting as a reversible Mn store in S. domuncula. According to this view, the presence of SubDo-03 bacteria is required as a protection against higher, toxic concentrations of Mn in the environment; manganese (II) after undergoing oxidation to manganese (IV), becomes an insoluble ion. Since only minute levels of manganese exist in the surrounding seawater a substantial accumulation of manganese has to arise, or a release by the bacterial-precipitated manganese (IV) is implicated to maintain the reversible balance. The other possible benefits provided by the bacterial association to the sponge could be in preventing cellular oxygen toxicity, help in nutrient scavenging and detoxification.

Metallic copper as an antimicrobial surface

Bacteria, yeasts, and viruses are rapidly killed on metallic copper surfaces, and the term "contact killing" has been coined for this process. While the phenomenon was already known in ancient times, it is currently receiving renewed attention. This is due to the potential use of copper as an antibacterial material in health care settings. Contact killing was observed to take place at a rate of at least 7 to 8 logs per hour, and no live microorganisms were generally recovered from copper surfaces after prolonged incubation. The antimicrobial activity of copper and copper alloys is now well established, and copper has recently been registered at the U.S. Environmental Protection Agency as the first solid antimicrobial material. In several clinical studies, copper has been evaluated for use on touch surfaces, such as door handles, bathroom fixtures, or bed rails, in attempts to curb nosocomial infections. In connection to these new applications of copper, it is important to understand the mechanism of contact killing since it may bear on central issues, such as the possibility of the emergence and spread of resistant organisms, cleaning procedures, and questions of material and object engineering. Recent work has shed light on mechanistic aspects of contact killing. These findings will be reviewed here and juxtaposed with the toxicity mechanisms of ionic copper. The merit of copper as a hygienic material in hospitals and related settings will also be discussed.

Killing of bacteria by copper surfaces involves dissolved copper

Bacteria are rapidly killed on copper surfaces. However, the mechanism of this process remains unclear. Using Enterococcus hirae, the effect of inactivation of copper homeostatic genes and of medium compositions on survival and copper dissolution was tested. The results support a role for dissolved copper ions in killing.

The copper-inducible ComR (YcfQ) repressor regulates expression of ComC (YcfR), which affects copper permeability of the outer membrane of Escherichia coli

The pathway of copper entry into Escherichia coli is still unknown. In an attempt to shed light on this process, a lux-based biosensor was utilized to monitor intracellular copper levels in situ. From a transposon-mutagenized library, strains were selected in which copper entry into cells was reduced, apparent as clones with reduced luminescence when grown in the presence of copper (low-glowers). One low-glower had a transposon insertion in the comR gene, which encodes a TetR-like transcriptional regulator. The mutant strain could be complemented by the comR gene on a plasmid, restoring luminescence to wild-type levels. ComR did not regulate its own expression, but was required for copper-induction of the neighboring, divergently transcribed comC gene, as shown by real-time quantitative PCR and with a promoter-lux fusion. The purified ComR regulator bound to the promoter region of the comC gene in vitro and was released by copper. By membrane fractionation, ComC was shown to be localized in the outer membrane. When grown in the presence of copper, ∆comC cells had higher periplasmic and cytoplasmic copper levels, compared to the wild-type, as assessed by the activation of the periplasmic CusRS sensor and the cytoplasmic CueR sensor, respectively. Thus, ComC is an outer membrane protein which lowers the permeability of the outer membrane to copper. The expression of ComC is controlled by ComR, a novel, TetR-like copper-responsive repressor.

Homeopathic Preparations of Quartz, Sulfur and Copper Sulfate Assessed by UV-Spectroscopy

Homeopathic preparations are used in homeopathy and anthroposophic medicine. Although there is evidence of effectiveness in several clinical studies, including double-blinded randomized controlled trials, their nature and mode of action could not be explained with current scientific approaches yet. Several physical methods have already been applied to investigate homeopathic preparations but it is yet unclear which methods are best suited to identify characteristic physicochemical properties of homeopathic preparations. The aim of this study was to investigate homeopathic preparations with UV-spectroscopy. In a blinded, randomized, controlled experiment homeopathic preparations of copper sulfate (CuSO(4); 11c-30c), quartz (SiO(2); 10c-30c, i.e., centesimal dilution steps) and sulfur (S; 11×-30×, i.e., decimal dilution steps) and controls (one-time succussed diluent) were investigated using UV-spectroscopy and tested for contamination by inductively coupled plasma mass spectrometry (ICP-MS). The UV transmission for homeopathic preparations of CuSO(4) preparations was significantly lower than in controls. The transmission seemed to be also lower for both SiO(2) and S, but not significant. The mean effect size (95% confidence interval) was similar for the homeopathic preparations: CuSO(4) (pooled data) 0.0544% (0.0260-0.0827%), SiO(2) 0.0323% (-0.0064% to 0.0710%) and S 0.0281% (-0.0520% to 0.1082%). UV transmission values of homeopathic preparations had a significantly higher variability compared to controls. In none of the samples the concentration of any element analyzed by ICP-MS exceeded 100 ppb. Lower transmission of UV light may indicate that homeopathic preparations are less structured or more dynamic than their succussed pure solvent.

Substitutions due to antiretroviral toxicity or contraindication in the first 3 years of antiretroviral therapy in a large South African cohort

INTRODUCTION: The patterns and reasons for antiretroviral therapy (ART) drug substitutions are poorly described in resource-limited settings. METHODS: Time to and reason for drug substitution were recorded in treatment-naive adults receiving ART in two primary care treatment programmes in Cape Town. The cumulative proportion of patients having therapy changed because of toxicity was described for each drug, and associations with these changes were explored in multivariate models. RESULTS: Analysis included 2,679 individuals followed for a median of 11 months. Median CD4+ T-cell count at baseline was 85 cells/microl. Mean weight was 59 kg, mean age was 32 years and 71% were women. All started non-nucleoside reverse transcriptase inhibitor-based ART (60% on efavrienz) and 75% started on stavudine (d4T). After 3 years, 75% remained in care on-site, of whom 72% remained on their initial regimen. Substitutions due to toxicity of nevirapine (8% by 3 years), efavirenz (2%) and zidovudine (8%) occurred early. Substitutions on d4T occurred in 21% of patients by 3 years, due to symptomatic hyperlactataemia (5%), lipodystrophy (9%) or peripheral neuropathy (6%), and continued to accumulate over time. Those at greatest risk of hyperlactataemia or lipodystrophy were women on ART > or =6 months, weighing > or =75 kg at baseline. DISCUSSION: A high proportion of adult patients are able to tolerate their initial ART regimen for up to 3 years. In most instances treatment-limiting toxicities occur early, but continue to accumulate over time in patients on d4T. Whilst awaiting other treatment options, the risks of known toxicities could be minimized through early identification of patients at the highest risk.

Copper induction of lactate oxidase of Lactococcus lactis: a novel metal stress response

Lactococcus lactis IL1403, a lactic acid bacterium widely used for food fermentation, is often exposed to stress conditions. One such condition is exposure to copper, such as in cheese making in copper vats. Copper is an essential micronutrient in prokaryotes and eukaryotes but can be toxic if in excess. Thus, copper homeostatic mechanisms, consisting chiefly of copper transporters and their regulators, have evolved in all organisms to control cytoplasmic copper levels. Using proteomics to identify novel proteins involved in the response of L. lactis IL1403 to copper, cells were exposed to 200 muM copper sulfate for 45 min, followed by resolution of the cytoplasmic fraction by two-dimensional gel electrophoresis. One protein strongly induced by copper was LctO, which was shown to be a NAD-independent lactate oxidase. It catalyzed the conversion of lactate to pyruvate in vivo and in vitro. Copper, cadmium, and silver induced LctO, as shown by real-time quantitative PCR. A copper-regulatory element was identified in the 5' region of the lctO gene and shown to interact with the CopR regulator, encoded by the unlinked copRZA operon. Induction of LctO by copper represents a novel copper stress response, and we suggest that it serves in the scavenging of molecular oxygen.

Copper and human health: biochemistry, genetics, and strategies for modeling dose-response relationships

Copper (Cu) and its alloys are used extensively in domestic and industrial applications. Cu is also an essential element in mammalian nutrition. Since both copper deficiency and copper excess produce adverse health effects, the dose-response curve is U-shaped, although the precise form has not yet been well characterized. Many animal and human studies were conducted on copper to provide a rich database from which data suitable for modeling the dose-response relationship for copper may be extracted. Possible dose-response modeling strategies are considered in this review, including those based on the benchmark dose and categorical regression. The usefulness of biologically based dose-response modeling techniques in understanding copper toxicity was difficult to assess at this time since the mechanisms underlying copper-induced toxicity have yet to be fully elucidated. A dose-response modeling strategy for copper toxicity was proposed associated with both deficiency and excess. This modeling strategy was applied to multiple studies of copper-induced toxicity, standardized with respect to severity of adverse health outcomes and selected on the basis of criteria reflecting the quality and relevance of individual studies. The use of a comprehensive database on copper-induced toxicity is essential for dose-response modeling since there is insufficient information in any single study to adequately characterize copper dose-response relationships. The dose-response modeling strategy envisioned here is designed to determine whether the existing toxicity data for copper excess or deficiency may be effectively utilized in defining the limits of the homeostatic range in humans and other species. By considering alternative techniques for determining a point of departure and low-dose extrapolation (including categorical regression, the benchmark dose, and identification of observed no-effect levels) this strategy will identify which techniques are most suitable for this purpose. This analysis also serves to identify areas in which additional data are needed to better define the characteristics of dose-response relationships for copper-induced toxicity in relation to excess or deficiency.

Reflection, refraction, and rejection : copper smelting heritage and the execution of environmental policy

This dissertation examines the global technological and environmental history of copper smelting and the conflict that developed between historic preservation and environmental remediation at major copper smelting sites in the United States after their productive periods ended. Part I of the dissertation is a synthetic overview of the history of copper smelting and its environmental impact. After reviewing the basic metallurgy of copper ores, the dissertation contains successive chapters on the history of copper smelting to 1640, culminating in the so-called German, or Continental, processing system; on the emergence of the rival Welsh system during the British industrial revolution; and on the growth of American dominance in copper production the late 19th and early 20th centuries. The latter chapter focuses, in particular, on three of the most important early American copper districts: Michigan’s Keweenaw Peninsula, Tennessee’s Copper Basin, and Butte-Anaconda, Montana. As these three districts went into decline and ultimately out of production, they left a rich industrial heritage and significant waste and pollution problems generated by increasingly more sophisticated technologies capable of commercially processing steadily growing volumes of decreasingly rich ores. Part II of the dissertation looks at the conflict between historic preservation and environmental remediation that emerged locally and nationally in copper districts as they went into decline and eventually ceased production. Locally, former copper mining communities often split between those who wished to commemorate a region’s past importance and develop heritage tourism, and local developers who wished to clear up and clean out old industrial sites for other purposes. Nationally, Congress passed laws in the 1960s and 1970s mandating the preservation of historical resources (National Historic Preservation Act) and laws mandating the cleanup of contaminated landscapes (CERCLA, or Superfund), objectives sometimes in conflict – especially in the case of copper smelting sites. The dissertation devotes individual chapters to the conflicts that developed between environmental remediation, particularly involving the Environmental Protection Agency and the heritage movement in the Tennessee, Montana, and Michigan copper districts. A concluding chapter provides a broad model to illustrate the relationship between industrial decline, federal environmental remediation activities, and the growth of heritage consciousness in former copper mining and smelting areas, analyzes why the outcome varied in the three areas, and suggests methods for dealing with heritage-remediation issues to minimize conflict and maximize heritage preservation.

The Effect of the Cu:Fe''' Ratio Upon the Current Efficiency in the Electrolysis of a Copper Sulfate Solution Containing Iron Sulfate

It is a well-known fact that, in the electrolysis of a CuSO4 solution containing iron sulfate, using insoluble anodes, with the depletion of copper, the point is finally reached where the current efficiency becomes zero. This decrease in current efficiency is due to the oxidation of the ferrous sulfate to the ferric condition at the anode, by the oxygen liberated. The resulting ferric sulfate diffuses over to the cathode and there dissolves copper from the cathode according to the chemical equation Cu + Fe2 (SO4)3 = CuSO4 + 2FeSO4. This copper, which has been deposited at the cathode by the electric current, is thus redissolved by the Fe2(SO4)3. The solution of the copper causes at the same time a formation of FeSO4 which in turn diffuses over to the anode and is there oxidized to Fe2(SO4)3; and so the cycle continues, using electric current without rendering useful work. E. H. Larison has noted that a definite amount of ferric salts must be reduced to the ferrous condition before all the copper will remain on the cathode; he does not state, however, just what this point is. L. Addicks has plotted the relation between current efficiency and ferric sulphate content. The existence of the results scattered the points more or less, although the decrease in current efficiency with increased ferric sulphate content is clearly indicated. E. T.Kern has likewise noted that the smaller the amount of copper in the solution, the greater is the reduction of current efficiency. In this work, therefore, it was desired to determine what amount of ferric iron was permissible in a copper sulfate solution of definite concentration before the current efficiency would drop to zero, and what, if any, was the effect of definite Cu:Fe’’’ratio upon the current efficiency of the electrolysis.