Acute Toxicity of Cresols to Pseudomonas — An Initial Oxygen Uptake Method

Acute toxicity of cresols to both Pseudomonas I and II was estimated by an initial oxygen uptake method. Inhibition studies of toluene and cresols on the oxidation of either benzoate by Pseudomnas I or phenol by Pseudomonas II were analyzed and expressed as oxygen uptake rates. Double reciprocal plots for the inhibiton by cresols of oxygen uptake in Pseudomonas, two physical constants, Vmaxi and Ki, were obtained. The Vmaxi of o?, m? and p-cresol were 80%, 81% and 57% of Vmax in Pseudomnas I, and 10%, 25% and 36% in Pseudomonas II, respectively. Thus, the toxicity to Pseudomonas I decreases in the order p- > o- ≥ m-cresol, whereas to Pseudomonas II, the order is changed to o- > m- > p-cresol. This difference in the toxicity order is probably due to the allosteric effect of p-cresol towards Pseudomonas II. Inasmuch as most compounds inhibit noncompetively, the relative toxicity of different compounds can be estimated by a new toxicity parameter RI (relative inhibition) which is defined as 100/Ki. By comparing the RI value of each compound, the toxicity to Pseudomonas I decreases in the order m-chlorophenol > p-cresol > p-chlorophenol > o-cresol ≥ m-cresol > o-chlorophenol > toluene > phenol.     

Facile synthesis,characterization and application of magnetic Fe3O4-coir pith composites for the removal of methyl violet from aqueous solution: Kinetics,isotherm, thermodynamics and parametric optimization

Dyes are commonly used in coloring clothes; in fertilizers, as anti-freezers, as detergents and so on. The use of such dyes has carcinogenic and genotoxic effects. These dyes require proper removal from the environment. Subsequently, a green and low-cost approach promises to adhere to sustainability of the environment while maximum removal of these toxic dyes. The present study describes removal of methyl violet (MV) dye by adsorption process magnetically separable Fe₃O₄-coir pith composites. The study was evaluated in batch system taking the optimum conditions as: pH: 7, contact time: 12 h, stirring speed: 200 rpm, concentration of dye: 100 mg/L, adsorbent weight: 3 g/L, temp.: 308 K. The central composite design approach of response surface methodology in design-expert software showed maximum removal efficiency (>98%) for optimal parameters. The experimental equilibrium data fitted reasonably well to Langmuir isotherm model. ANOVA analysis along with Fisher's statistical test was also performed to validate the model. The predicted model was at par with the experimental values with adjusted R² of 0.9914. A thorough investigation of kinetic ($R_{\text{Pseudo second order}}^2$ = 0.99; $R_{\text{Pseudo second order}}^2=0.97;R_{\text{intra}?\text{particle diffusion}}^2=0.98)$, thermodynamic, adsorption isotherm $(R_{\text{Langmuir isotherm}}^2=0.997$ $R_{\text{Freundlich isotherm}}^2=0.99$ and eco-toxicological characteristics were performed for proper evaluations of the properties as well as sustainability of the adsorbent material. The whole research indicated encouraging potential of the developed material for adsorption, reusability and sustainability in applications for industrial scale wastewater treatment.     

An Opportunity for Recycling Semi‐dry Scrubber Residues Directly from Municipal Solid Waste Incineration Plants without Concern of Leaching Toxicity

The leaching behaviors of heavy metals from semi‐dry scrubber (SDS) residues of municipal solid waste incineration (MSWI) plants are re‐investigated. The most leachable heavy metals in semi‐dry scrubber residues from municipal solid waste incinerators are found to be chromium ions (Cr(III) and Cr(VI)), but neither lead nor cadmium. Both of the leachabilities of Cr(III) and Cr(VI) in MSWI scrubber residue are a function of the CaO/Al₂O₃ ratio of residues. The pH‐dependent leaching behaviors are only observed in the case of Cr(III), but not for Cr(VI). Our results show that it is worth recycling SDS residues which possess a lower chemical composition ratio of CaO/Al₂O₃, in order to reduce the potential risk of toxic leaching of chromium species.     

Iron uptake and toxicity in Caco-2 cells

The differences between the in vitro effects of iron attributed to valence, chelation, and complexation are known in terms of markers of oxidative stress. Few studies, however, describe the effects of iron on general markers of toxicity used in the testing of cell cultures. The aim of the present study was to determine the toxicity and uptake of different salts and iron complexes in the human intestinal cell line, Caco-2.Cells were incubated with 1.5 mM of different species of iron [FeCl₃/nitrilotriacetic acid (NTA) (1:2), FeCl₃/citric acid (1:2), FeCl₃ and FeSO₄] for 22–24 h. Thereafter, toxicological and uptake experiments were performed.The iron uptake, viability (via MTT assay), and membrane stability (via LDH release) of Caco-2 cells incubated with various iron forms differed significantly from untreated controls which showed no detrimental effects on cells and less iron uptake. The lowest signal for cell viability (MTT assay) was found after the incubation of the cells with FeCl₃/citric acid, being significantly different to treatment with FeCl₃, where the highest MTT signal was detected (p=0.002). No differences between the tested iron species could be found regarding cell proliferation (via serial cell counting) and viability using the trypan blue exclusion test. The lowest membrane damage (via LDH release) was registered in cells treated with FeCl₃/citric acid (1:2), whereas the highest LDH release could be found in cells incubated with FeCl₃/NTA (1:2). The highest intracellular iron concentration (measured via GFAAS) was detected after the treatment of Caco-2 cells with FeCl₃ and FeCl₃/NTA (1:2).This study substantiates the importance of the choice of complexes, as NTA seemed to enhance the toxicity of iron, while citric acid inhibited iron uptake and toxicity.     

Solid-phase extraction for toxicity reduction evaluations of industrial wastewater effluents

The physical, chemical and biological characteristics of industrial and municipal wastewater effluents in the United States are limited in National Pollutant Discharge Elimination System (NPDES) permits. Toxicity reduction evaluations (TREs) involving fractionation of wastewater effluents, biomonitoring for aquatic toxicity and determinations of specific chemicals are conducted when adverse effects on water quality are detected during routine biomonitoring as required by the NPDES permit. However, certain fractionation techniques are incompatible with subsequent testing for aquatic toxicity. The effect of various schemes for fractionation of wastewater effluent on biomonitoring with freshwater Cladocerans (Daphnia magna, Daphnia pulex, Ceriodaphnia dubia or Ceriodaphnia reticulata) is reviewed. Solid-phase extraction (SPE) is discussed as a chromatographic technique used for the selective fractionation of wastewater effluents during toxicity reduction evaluation.     

Investigation of the chemical markers for experiential quality evaluation of crude aconite by UHPLC–Q‐TOF‐MS

Many foods and herbs are experientially classified into different commodity grades in commercial circulation. Regarding the hypertoxic herb aconite, large samples are considered to be of better quality. However, this experiential classification lacks a scientific basis. In this study, we focused on the quality diversity among different grades and studied it using the minimum lethal dose assay and a novel ultra high performance liquid chromatography coupled with time‐of‐flight mass spectrometry method. Toxicity assay result suggested grade I aconite had the lowest toxicity (p < 0.05). Using this method with partial least squares‐discriminant analysis, we discovered nine chemomarkers, including neoline, songorine, fuziline, mesaconitine, talatizidine, dexyaconitine, talatisamine, hypaconitine, and fuzitine. Considering their toxicity and activity, we found the levels of toxic ingredients hypaconitine, dexyaconitine, and mesaconitine in grade I were lower than those in grade II (p < 0.01), while the levels of efficacy ingredients songorine, talatisamine, and neoline were the highest in grade I (p < 0.01). Further study demonstrated that the quality variation was associated with plant tissue development and toxic ingredient distribution law. Our results provide scientific evidence for the experiential quality evaluation of aconite, and it will be of great utility for other foods and herbs.     

Whole-cell luminescence-based flow-through biodetector for toxicity testing

A new type of biodetector was designed based on a bioluminescence test with the bacterium Vibrio fischeri performed in a liquid continuous flow-through system. Here we describe the modification of a commercial tube luminescence detector to work in the flow mode by building a new flow cell holder and a new case including “top cover” to connect the flow cell with the waste and the incubation capillary in a light-proof manner. As different samples were injected successively it was necessary to keep the individual peaks separated. This was done using an air-segmented flow in the reaction coil. To afford fast screening, the incubation time of the sample and the Vibrio fischeri, which equaled the dead time of the detection system, was set at 5.6 min. Rapid monitoring of toxic substances is achieved by using 20 μL of sample and flow-rates of 110–150 μL min⁻¹. As a proof-of-principle, we show results for the detection of five selected di-, tri- and tetrachlorophenols at different concentrations varying from 1 to 200 mg L⁻¹. Calculation of inhibition rates and EC₅₀ values were performed and compared with corresponding values from the DIN EN ISO 11348-2 microplate format. Compared with the latter, the inhibition rates obtained with our flow-through biodetector for the compounds tested were generally about twofold lower, but importantly, a much faster detection is possible. Figure Flow scheme of the biodetector setup     

Biomedical application and hidden toxicity of Zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnO NPs) represent a novel type of metal oxide nanoparticles enabling a new horizon for biomedical applications spanning from diagnosis to treatment. ZnO NPs are extensively used in commercial products such as sunscreens and daily-care products. Apart from that, ZnO NPs are used in food packaging and ointments and as an antimicrobial and antifungal agent. They are extensively used for many biomedical applications noticeably in pharmaceutics and theranostics. Its exceptional optical, electrical, and physiochemical properties, notably its incredible surface chemistry, make ZnO NPs a reliable option for bioimaging, biosensors, antimicrobial action, and drug and gene delivery. The present review covers findings and developments in ZnO NPs research in relation to its application and toxicity mechanism. A special emphasis has been given to the neurotoxic potential of the ZnO NPs and glial cell toxicity. Various factors contributing to the toxic potential of ZnO NPs and cell signaling pathways concerning its toxicity are also discussed. Available data point toward the risk of uncontrollable use of zinc nanoformulation. With increasing use, ZnO NPs pose a severe threat both to the ecosystem and human beings. In a nutshell, the review outlines the current state of the art of ZnO NPs.