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Chromium (Cr) is a potentially toxic metal occurring in the soil as a result of natural and anthropogenic activities and is mainly found in Cr3+ and Cr6+. The hexavalent chromium has toxic effects on plants, animals, humans and microorganisms depending on exposure level, duration and doses. Biochar is a stable carbon-based material that has been widely documented to immobilize metals in contaminated soils and for soil remediation effectively. The present 90 days incubation study was conducted to investigate the potential use of rice stubble and sawdust-derived modified biochars on Cr6+ remediation and their effects on nutrient availability. Among the treatments, modified rice stubble biochar (RSB-M) contained the highest surface area, pore volume and CEC. The unmodified and modified biochars significantly increased soil pH, EC, CEC, and N, K availability ((p < 0.001)). Statistical analysis showed that modified rice stubble (RSB-M) and sawdust biochars (SDB-M) significantly reduced the Cr6+ with incubation days compared to unmodified biochars, possibly due to the greater porous structure and various functional groups. The submerged incubation condition also greatly impacted Cr6+ reduction since a gradual decrease (up to ~70 mg kg−1 of Cr6+) was observed in control treatments. Therefore, applying modified biochars is imperative to alleviate Cr6+ polluted soils and improve soil fertility. [ABSTRACT FROM AUTHOR]

Using calcium polysulfide as the reducing agent, synthetic zeolite as the adsorbent, and cement as the curing agent, the dual-index orthogonal test method was used to determine the best remediation dosage of chromium-contaminated soil. On this basis, through the dry–wet cycle test, the durability of the chromium-contaminated soil after repair is analyzed from the perspectives of unconfined compressive strength, toxic leaching concentration, quality loss, and microscopic characterization. Test results showed that the optimal ratio for the joint repair of chromium-contaminated soil was 3 times the amount of CaS5, 15% synthetic zeolite, and 20% cement. With the increase in the number of wet–dry cycles, the unconfined compressive strength of the composite preparation combined to repair chromium-contaminated soil was first increased and then reduced, and the concentration of Cr(VI) and total chromium in the leachate was first decreased and then increased. The higher the chromium content of the contaminated soil was, the lower the unconfined compressive strength, and the higher the leaching concentration of Cr(VI) and total chromium were. With the increase in cycle times, the cumulative mass-loss rate of composite preparations for repairing chromium-contaminated soil gradually increased, and the higher the chromium content was, the higher the cumulative mass-loss rate, which was less than 2%, reflecting the combination of composite preparations for repairing chromium-contaminated soil to have good durability. Microscopic and macroscopic results are consistent with each other. [ABSTRACT FROM AUTHOR]

Disposal of industrial waste is of great concern because it releases toxic metals resulting into the degradation of environments and consequently causes health effects on humans. The present study was carried out with the objectives of identifying the possible source and migration of contaminants in the surface water and groundwater and the associated health risks in the industrial region of Ranipet, Tamil Nadu, India. A total of 22 water samples were collected and analysed for the concentration of major ions and trace elements. Chemical speciation of chromium and lead in surface and groundwater was calculated using the geochemical code, PHREEQC. The concentration of total dissolved solids, chromium and lead was high in the surface water than groundwater in this region. The chromium in most of the sampled water is dominated with Cr(OH)2+ and Cr(OH)3 species and the dominant species of lead was PbCO3. The major source of contamination is the waste dumped in this region and also the improper disposal of effluents from the small-scale industries in this region. Use of groundwater with the present level of chromium and lead in this region will cause several health effects through oral and dermal pathways. Hence, stringent monitoring of quality of water sources of this region, enforcement of regulation of the disposal of wastes from the industries, recover and treat the dumped solid waste are very much necessary to prevent the spread of contamination. [ABSTRACT FROM AUTHOR]

Remediation of heavy metal contaminated soil and water has been investigated through various methods, most of these have been shown to be expensive and sometimes result in the generation of toxic sludge. In situ methods such as phytoremediation have therefore been explored for their green, economical and less environmentally disruptive advantages. This study investigates the use of vetiver grass in the remediation of chromium(VI) from wastewater. The grass is known to grow in both soil and water. The efficiency of the vetiver grass in the removal of Cr(VI) was examined using 2 L solutions of varying concentrations. The initial concentrations of Cr(VI) chosen for the study were 5 ppm, 10 ppm, 30 ppm and 70 ppm. In a seven (7) week period, 87 % reduction in Cr(VI) concentration was observed in the 5 ppm bucket, while 51 % Cr(VI) removal was measured in the 10 ppm bucket. The 30 ppm bucket had a removal efficiency of 28 % in 5 weeks and 12 % removal efficiency in 4 weeks was measured in the 70 ppm bucket. The absorption of chromium was higher in the roots than the leaves at 5 ppm and 10 ppm, whereas it was higher in the leaves than in the roots at 30 ppm and 70 ppm. The results show the potential of vetiver grass in phytoextraction of chromium and its hyperaccumulator potential for other heavy metals. [ABSTRACT FROM AUTHOR]

Abstract Bioremediation is a sustainable and cost-effective means of contaminant detoxification. Although Cr(VI) is toxic at high concentrations, various microbes can utilise it as an electron accepter in the bioremediation process, and reduce it to the less toxic form Cr(III). During remediation, it is important to monitor the level of toxicity and effectiveness of Cr(VI) reduction in order to optimize the conditions. This study employed a whole-cell bioreporter Acinetobacter baylyi ADPWH- rec A to access the degree of toxicity of different species of Cr over a range of initial concentrations. It also investigated whether Cr isotope fractionation factors were impacted by different levels of Cr toxicity (related to its concentration) and Cr(VI) reduction rates by Cr resistant bacteria Pseudomonas fluorescens LB 300. The results show that, of both Cr 2 O 7 2− and CrO 4 2−, the whole-cell bioreporter was efficient in indicating the level of genotoxicity of Cr(VI) at low concentrations and cytotoxicity at high concentrations via variations of bioluminescence. High concentrations (> 100 mg/L) of Cr(III) could also strongly induce the luminescence in the bioreporter, indicating DNA damage at such abundance. Pseudomonas fluorescens LB 300 was found to be effective in reducing Cr(VI) even when the concentration was high (40 mg/L); however, complete Cr(VI) reduction was only observed at low concentrations (< 5 mg/L), since the toxicity of high concentrations of Cr(VI) impacted the effectiveness of reduction by the bacteria. During reduction, the C 53 r / C 52 r ratio of remaining Cr(VI) increased from its initial value, and the calculated fractionation factor by bacterial Cr(VI) reduction (ε) was −3.1±0.3‰. The fractionation factor was independent of the initial Cr(VI) concentration. Therefore, a single Cr isotope fractionation factor can be effectively applied in indicating the extent of bioremediation processing of Cr(VI) over a wide range of concentrations. This significantly simplified monitoring of Cr(VI) depletion in bioremediation, since variations of ε normally indicate a change in the reduction mechanism and therefore would complicate the elucidation of processes driving the remediation. Graphical abstract Image 1 Highlights • Whole-cell bioreporter is efficient in indicating the degree of Cr toxicity. • Cr toxicity can impact on the reduction rates and effectiveness of Cr(VI) reduction by bacteria. • Bacterial Cr isotope fractionation factor is independent of the initial Cr(VI) concentration. • Cr isotope techniques are useful in estimating the extent of Cr(VI) bioremediation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Cr bioaccessibilities in order: gastric > active colon > small intestinal phase. • The Cr(III) was a large part of Cr speciation in the digestive juices. • Human gut microbiota accelerated the reduction of Cr(VI) to less toxic Cr(III). Abstract There is limited research concentrating on the effects of gut microbiota on the bioaccessibility and speciation of chromium (Cr) in vegetables. In this study, the physiologically based extraction test (PBET) and the unified BARGE method (UBM), were combined with the simulator of human intestinal microbial ecosystems (SHIME) to determine the bioaccessibility and speciation of Cr from vegetables. The results showed that the Cr bioaccessibility was the highest in the gastric phase. The Cr bioaccessibility from the water spinach was the highest, and was 1.6–3.4 and 1.1–1.8 times that of leaf lettuce and celery, respectively. The Cr bioaccessibilities of the UBM method were slightly greater than those of the PBET method. Additionally, the gut microbiota increased the Cr bioaccessibility and reduced more toxic Cr(VI) to less toxic Cr(III) from vegetables. Therefore, our study reveals the possible health risks of consuming Cr-contaminated vegetables based on the bioaccessibility and speciation of Cr. [ABSTRACT FROM AUTHOR]

Hexavalent chromium or Cr(VI) is toxic. Therefore, it is necessary to prevent or minimize its existence. This study aims to explain the effect of using mimosa as a retanning agent on the reduction of Cr(VI) content in goat crust skin. The post-tanning process was done by the process of 1st retanning, neutralization, fatliquoring, 2nd retanning and fixing. The retanning process 2 was performed with three treatments, 0% of mimosa, 3% of mimosa and 6% of mimosa. All the data were analyzed by the One Way ANOVA then followed by the Duncan Multiple Range Test. The results obtained were the decrease of hexavalent chromium content with the addition of mimosa during the retanning process. The use of 3% of mimosa is more effective to reduce the formation of Cr(VI) than 6% of mimosa. It can be said that the use of mimosa as a retanning agent can reduce the formation of Cr(VI). [ABSTRACT FROM AUTHOR]

The release of heavy metals in the environment is a serious threat causing health hazards to living beings. Hence, it is essential to remediate chemical contamination for a safe environment. Bioremediation is considered one of the most cost-effective and sustainable agricultural techniques, in contrast with other conventional methods to reduce chromium toxicity in agricultural lands polluted with chromium, as it is a natural way to mitigate the toxic effects of hexavalent chromium with simultaneous amelioration in the growth of plants. In the current study, an attempt was made to reduce toxicity of chromium by using six plant growth-promoting chromium-resistant bacteria (Bacillus pumilus (ALa), Bacillus atrophaeus (BL2), Bacillus cereus (AR), Staphylococcus lentus (E3), T2aii and W6ii) for enhancing the growth of Zea mays L. in soil contaminated with chromium. In this regard, a pot experiment was conducted with pre-germination and post-germination inoculation treatments to Zea mays seeds in the presence of chromium stress, i.e., 200, 400, and 600 μg/ml. Our results have shown that toxicity of chromium caused a reduction in photosynthetic pigments and protein content together with reduction in growth parameters of plants, while treatments with chromium-resistant PGPB significantly enhanced chromium tolerance in treated plants compared with non-inoculated treatments in the presence of chromium stress. The present investigation suggests that applying post-germination inoculation treatments is an effective technique for improved plant growth and heavy metal alleviation in metal-contaminated soil. Thus, our current work revealed an incentive approach toward the green revolution in the age of industrialization by exploring beneficial chromium-tolerant auxin-producing microbes. [ABSTRACT FROM AUTHOR]

The populations of wild animals are declining in many parts of the world in response to man-made alterations in the environment. Environmental contamination due to heavy metals discharge from industry may contribute to the decline of wild animal populations by impacting their reproduction, growth, and development. In the leather tanning industry, chromium (Cr) is used as a basic component, but it is a potent toxicant that can affect many of the physiological functions of animals. In the current study, we investigated the reproductive toxicity of industrial Cr in female small Indian mongooses inhabiting a tannery area. Adult female specimens were live trapped from February 2015 to January 2016. Blood and other body tissues (ovaries, kidneys and liver) of the captured specimens were collected along with soil and water samples from the environment for analysis. The Cr concentrations were found significantly (p < 0.0001) increased compared to control in the environment, blood, and all body tissues of the animals. Estradiol and progesterone levels were found to be significantly decreased in comparison with control (p < 0.0001), along with reduced ovarian weights, while follicle stimulating hormone (FSH) and luteinizing hormone levels were found significantly (p < 0.0001) elevated. Light microscopy revealed significantly decreased in comparison with control ovarian follicle numbers (p < 0.0001) and diameters, vacuolization of the oocytes, and a significantly higher percentage of atretic follicles inside the ovary. We conclude that Cr discharged from the tanneries is absorbed by the exposed female small Indian mongoose, leading to ovarian dysfunction with potential impairment of reproductive function. [ABSTRACT FROM AUTHOR]

Abstract This work focuses on developing some composites of desirable properties mainly for heavy metal ion adsorption from the water bodies leading to water remediation. Adsorption of Cr(VI) by a novel biopolymer-based hybrid nanocomposite material has been synthesized via emulsifier-free emulsion polymerisation technique and investigated its assess as proposed use. Chitosan is a biocompatible, biodegradable and non-toxic material, hence this biopolymer has been selected in this research work. The chemical modification of the biopolymer chitosan has been achieved via grafting of poly(methyl methacrylate) (PMMA) and crosslinker silica gel was added in order to improve the mechanical strength of the nanocomposite in nitrogen atmosphere taking ammonium persulphate as initiator. The resulting composite samples were characterized by using XRD, FTIR, SEM and TEM. Further, the biodegradability of the samples was studied at different time intervals from 15 days to 6 months and the so produced nanocomposite exhibited good biodegradability. Adsorption of Chromium (Cr) was investigated by varying the contact time between the adsorbate (Cr), the nanocomposite, pH of the solution and the doses of the composite. The optimum result for chromium removal was found at pH-4 and this result showed its use efficiently for the treatment of wastewater containing Cr (VI). Highlights • A novel chitosan-based BNC has been synthesized via emulsifier free emulsion polymerization for enhancing biodegradability. • The so formed bionanocomposites has been characterized by FTIR, XRD, SEM and TEM. • To remove Cr(VI) for environmental concern. At an optimum pH of 4 leading to 98% recovery towards water remediation. [ABSTRACT FROM AUTHOR]

Abstract The chromium toxicity greatly depends on its oxidation state and therefore accurate determination of all Cr species is essential to understand its potential health risk. Numerous critical reviews have underlined the exposure to especially Cr(III) and Cr(VI) species in various matrices but the chromium speciation in biological samples has not been discussed yet. Therefore, the objective of this article is to review recent advances in chromium speciation in various biological samples. Up to now, the most widely studied biological samples are urine, whole blood, serum, plasma but few studies dealing with tissues, saliva and joint effusion have been published as well. The major emphasis is put on the sampling, different pre-treatment procedures, and application of off-line and on-line techniques based on different atomic spectrometry methods together with their validation. A partial attention has been paid on the diversity of Cr species in biological samples as well as their interconversions together with the suggested speciated isotope dilution (SID) approach representing a valuable tool for correction of these interconversions. Graphical abstract Unlabelled Image Highlights • A critical review of chromium speciation in biological samples is presented. • Chromium species interconversion is discussed. • Comparison of on-line and off-line techniques is provided. • Validation of measurement procedures alongside with obtained data is summarized. [ABSTRACT FROM AUTHOR]

Chelate employed wrenching out of Chromium from contaminated soils is a comparably new technology. The pot culture experiments were carried out to study the toxicological, physiological and biochemical changes in Lemongrass using different chelators such as Ethylenediaminetetraaceticacid (EDTA), Diethylenetriaminepentaacetic acid (DTPA), Citric acid (CA) and Salicylic acid (SA) and metal ions (Fe, Mg and Zn) in Cr+6 contaminated soil. The application of heavy metal Cr induced number of adverse consequences like reduction in root/shoot length, biomass and chlorophyl content in Lemongrass plants grown in soil with Cr+6 (50mgkg−1). On the contrary, the growth of Lemongrass was stimulated by the addition of chelators such as EDTA, DTPA, Citric acid, salicylic acid including metal ions (Fe, Mg and Zn). The increase in proline content was associated with the synthesis of antioxidant enzymes by the applications of chelators and metal ions. The treated plants with reduced Transportation index (Ti) values indicated more root Chromium accumulation as compared to shoot. The Bio-Concentration Factor (BCF) and Total Accumulation Rate (TAR) of Chromium were elevated with the supplementation of chelators and metal ions, thus, illustrating more metal bioavailability in plants. [ABSTRACT FROM AUTHOR]

The effect of chromium (Cr) toxicity on four cultivars of mustard (Brassica juncea), Varuna, Pusa Bold, Rohini and SS2, was studied to select the cultivar with the highest tolerance potential based on higher photosynthesis and growth and lower oxidative stress. Plants receiving Cr showed enhanced superoxide production, accumulation of H2O2 and lipid peroxidation and reductions in photosynthesis and growth. We also studied the potential of ethephon (ethylene source; 2-chloroethyl phosphonic acid) in the amelioration of Cr-induced oxidative stress in the Varuna cultivar which had the highest tolerance potential. Supplementation of plants with ethylene resulted in the alleviation of Cr-induced stress by enhancing proline accumulation and the activity of proline metabolism enzymes and glutamyl kinase, and reduction in proline oxidase activity. Ethylene also increased the activity of enzymes of sulfur assimilation, ATP-sulfurylase and serine acetyl transferase and the content of reduced glutathione (GSH). Furthermore, application of ethylene to plants under Cr stress resulted in ethylene levels in the optimal range and increased the activity of anti-oxidant enzymes such as glutathione reductase and ascorbate peroxidase, reduced oxidative stress and increased photosynthesis and growth. The key role of ethylene in the reversal of Cr-induced photosynthetic inhibition was clearly seen with the application of the ethylene action inhibitor, silver nitrate (AgNO3). The supplementation of AgNO3 resulted in decreased GSH and proline content and lowered ethylene production and photosynthetic and growth compared to ethylene-treated plants. This suggests that ethylene is involved in -reversal of Cr inhibited photosynthesis and growth in mustard. [ABSTRACT FROM AUTHOR]

Rapid industrialization is potentially contaminating the environment. Tannery is one of the industries producing very high amount of effluents, having a significant quantity of chromium (Cr) along with other pollutants. Due to a water shortage in Pakistan, farmers are using wastewater from tanneries for irrigation, which markedly reduces plant growth and biomass. Irrigation of crops with tannery wastewater is one of the main sources of Cr entry into the food web, which is a major threat to human beings. The present study was planned to investigate the effect of tannery wastewater on wheat plants and the role of fulvic acid (FA) in Cr toxicity alleviation. Results showed that application of tannery wastewater reduced plant growth, biomass, and photosynthetic pigments. Application of wastewater induced oxidative damage and lipid peroxidation in wheat plants. The application of FA played a very beneficial role in Cr toxicity alleviation in wheat plants irrigated with wastewater. Fulvic acid enhanced plant growth, biomass, and photosynthetic pigments, while reducing oxidative damage, lipid peroxidation, and Cr accumulation in stressed plants. It is concluded that application of FA in crops, irrigated with tannery wastewater, is one of the best strategies to mitigate Cr toxicity in plants. [ABSTRACT FROM AUTHOR]

Chromium (Cr) is a very toxic heavy metal present in agricultural soils. Soils contaminated with Cr are the major source of Cr entrance into the food chain. The present experiment was designed to determine the effects of different levels of lysine chelated with zinc (Zn-lys) (0, 10, 20, 30 mg L−1) upon photosynthesis, biomass, anti-oxidant enzyme activities, oxidative stress, and the uptake of Cr by rice under various applied levels of Cr (0, 100, 500 mg kg−1). Cr stress decreased the physiological and morphological parameters as well as the activities of anti-oxidants enzymes; and caused oxidative stress by enhancing the Cr concentration in plants over that of controls. Zn-lys foliar treatment enhanced photosynthesis, biomass, Zn contents, and enzyme activities. The application of Zn-lys (30 mg L−1) under 500 mg kg−1 of Cr increased plant height by 50% and shoot dry weight by 74% but also the root dry weight by 129% over the control treatment. In addition, Zn-lys reduced oxidative stress and Cr concentration compared to that of Cr treatments alone. The application of Zn-lys (30 mg L−1) also reduced Cr contents in roots by 26 and 31% in 100 and 500 mg kg−1 Cr treatments, respectively. The results of our study revealed that Zn-lys foliar treatment enhanced rice growth and decreased oxidative stress and Cr concentration by stimulating the anti-oxidant defense system as well as by promoting photosynthesis and Zn uptake in rice plants. Overall, the Zn-lys foliar treatment was helpful in increasing plant growth and Zn concentration while reducing the Cr contents in rice. However, further studies at field levels are required to explore the mechanisms of Zn-lys mediated reduction of Cr and possibly other heavy metal toxicity in plants. [ABSTRACT FROM AUTHOR]

Abstract Toxic chromium [(Cr(VI)] in food chain has created an alarming situation for human life and ecosystems. The present study through a greenhouse pot experiment aims to (a) investigate the ability of organic matter in reducing Cr uptake by lettuce (Lactuca sativa L.) from a sandy loam soil irrigating with Cr(VI)-water, (b) to provide a way for the restriction of Cr transfer from contaminated soils and irrigation water to plants/crops and (c) to contribute to the better management of soil (land) and water use, without reduction of the agricultural production. Since soil and groundwater contamination by Cr is a potential risk in a worldwide scale, due to industrial activities and/or natural processes, organic carbon may play a key role in the mobility of added Cr(VI) to soil via irrigation water, in a significant way. The cultivation of lettuce, using organic matter in the form of leonardite (10 and 30 wt%) and Cr(VI)-irrigation water (100, 200 and 300 mgL−1), showed that the uptake of Cr in both shoots and roots increased with increasing concentration of Cr in the irrigation water. The highest Cr values in shoots (average = 10 mg/kg) and in roots (average = 28 mg/kg) were recorded in those plants cultivated in soil after the addition of Cr(VI)- water without organic matter, whereas the lowest Cr values in shoots (average = 0.44 mg/kg) and in roots (average = 0.7 mg/kg) were recorded in those plants cultivated in soil with addition of 30 wt% organic matter. The used leonardite as organic matter that is an oxidized form of lignite, due to its high content of humic acid is considered to be a useful organic fertilizer that provides possibilities for combining food production with soil protection. Therefore, the application of the natural organic material leonardite, as a land management technique, seems to be a cost-effective method consistent to related protocols for the protection of the soil quality. Graphical abstract Image 1 Highlights • Cr uptake by lettuce from a sandy loam soil irrigated with Cr(VI)-water. • Added leonardite reduced significantly Cr accumulation in roots and shoots. • Negative correlation between pH and Eh (mV) of the cultivated soil. • Negative correlation between organic carbon and Cr accumulation. • Restriction of Cr transfer from contaminated soils and waters to food chain. [ABSTRACT FROM AUTHOR]

3D NiO/polyaniline p-p junction foam was prepared and applied for electrochemical detection of Cr 6+ . The electrochemical detection using interfacial potential barrier was illustrated and a mature theoretical model was built to demonstrate the mechanism. Electrochemical sensing signals of targets can be revealed by changing the height of potential barrier after specific adsorption. The extra high sensitivity (0.78 μA nM −1 ) and low detection limit (3.96 × 10 −4  nM) of Cr 6+ were achieved by applying the p-p junction interfacial potential barrier as driven factors. This work proposes a model to apply the potential barrier for electrochemical detection of metal ions, which can be further developed for a wide range of specific substance detection. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate Cr toxicity in young plants of the CCN 51 Theobroma cacao genotype at different concentrations of Cr 3+ in the soil (0, 100, 200, 400 and 600 mg kg −1 ) through physiological, ultrastructural, antioxidant and molecular changes. Doses of 400 and 600 mg Cr 3+ kg −1 soil severely affected foliar gas exchange, promoted by damages in photosynthetic machinery evidenced by the decrease in CO 2 fixation. Decreased expression of psbA and psbO genes, changes in enzymatic activity and lipid peroxidation also affected leaf gas exchange. A hormesis effect was observed at 100 mg Cr 3+ kg −1 soil for the photosynthetic activity. As a metal exclusion response, the roots of the cocoa plants immobilized, on average, 75% of the total Cr absorbed. Ultrastructural changes in leaf mesophyll and roots, with destruction of mitochondria, plasmolysis and formation of vesicles, were related to the oxidative stress promoted by excess ROS. The activity of the antioxidant enzymes SOD, APX, GPX and CAT and the amino acid proline coincided with the greater expression of the sod cyt gene demonstrating synchronicity in the elimination of ROS. It was concluded, therefore, that the tolerance of the cocoa plants to the toxicity of Cr 3+ depends on the concentration and time of exposure to the metal. Higher doses of Cr 3+ in the soil promoted irreversible damage to the photosynthetic machinery and the cellular ultrastructure, interfering in the enzymatic and non-enzymatic systems related to oxidative stress and gene expression. However, the low mobility of the metal to the leaf is presented as a strategy of tolerance to Cr 3+ . [ABSTRACT FROM AUTHOR]

Hexavalent chromium [Cr(VI)] is the most toxic and potent form of chromium and induces multiple organ damage in humans and experimental animals. Oxidative stress has been implicated in the toxicity of Cr(VI). We have examined the potential role of 3,4-dihydroxybenzaldehyde (DHB), a plant polyphenolic antioxidant, in protecting human erythrocytes and lymphocytes from Cr(VI)-induced cytotoxicity and genotoxicity. Erythrocytes were treated with potassium dichromate, a Cr(VI) compound, in presence and absence of DHB. Incubation of erythrocytes with Cr(VI) enhanced the generation of reactive oxygen and nitrogen species, increased lipid and protein oxidation, methemoglobin levels, and lowered antioxidant power of cells. However, prior treatment of erythrocytes with DHB, resulted in a significant DHB dose-dependent decrease in reactive oxygen and nitrogen species levels and restoration of oxidative stress parameters. DHB also improved the antioxidant power of erythrocytes and restored the activities of major antioxidant, metabolic and membrane bound enzymes. Electron microscopic studies images DHB prevented Cr(VI)-induced morphological changes in erythrocytes. The single cell gel electrophoresis assay showed that DHB mitigated Cr(VI)-induced DNA damage in lymphocytes. These results clearly show that DHB protects human blood cells from Cr(VI)-induced oxidative damage and can be potentially used in reducing the toxic effects of this metal ion. [ABSTRACT FROM AUTHOR]

Present study was designed to assess the hexavalent chromium (Cr 6+ ) mediated oxidative stress that induces DNA damage and apoptosis in adult fish, Channa punctatus (35 ± 3.0 g; 14.5 ± 1.0 cm; Actinopterygii). Fishes were maintained in three groups for 15, 30 and 45 d of exposure periods. They were treated with 5% (Group T1) and 10% (Group T2) of 96 h-LC 50 of chromium trioxide (Cr 6+ ). Controls were run for the similar duration. A significant (p < 0.05) increment in the activities of antioxidant enzymes, SOD and CAT in liver tissues of the exposed fish evinces the persistence of oxidative stress. A significant (p < 0.05) increase in induction of micronuclei (MN) coupled with transcriptional responses of target genes related to antioxidant enzymes, DNA damage and apoptosis ( sod, cat, gsr, nox-1, p53, bax, bcl-2, apaf-1 and casp3a ) establishes the impact of oxidative stress due to in vivo , Cr 6+ accumulation in liver as compared to control (0 mg/L), in a dose and exposure-dependent manner. Initially, the increased level of reactive oxygen species (ROS) in liver coincided with that of enhanced mRNA expression of antioxidant enzymes, sod, cat, gsr and nox-1 but, later, the overproduction of ROS, after 45 d of exposure of Cr 6+ , resulted in a significant (p < 0.05) up-regulation of p53. Our findings also unveil that the up-regulation of bax, apaf-1 and casp3a and down-regulation of bcl-2 are associated with Cr 6+ -induced oxidative stress mediated-apoptosis in liver of test fish. Aforesaid molecular markers can, thus, be efficiently utilized for bio-monitoring of aquatic regimes and conservation of fish biodiversity. [ABSTRACT FROM AUTHOR]

To examine the mechanism of hexavalent chromium [Cr(VI)]-induced carcinogenesis, a cross-sectional study in workers with or without exposure to Cr(VI) as well as in vitro administration of Cr(VI) in 16HBE cells was conducted. We explored the associations between Cr(VI) exposure, methylation modification of DNA repair genes and their expression levels, and genetic damage. Results showed that hypermethylation of CpG sites were observed in both occupationally exposed workers and 16HBE cells administrated Cr(VI). DNA damage markers including 8-hydroxydeoxyguanosine (8-OHdG) and micronucleus frequency in Cr(VI)-exposed workers were significantly higher than the control group. Among workers, blood Cr concentration was positively correlaed with the methylation level of CpG sites in DNA repair genes including CpG6,7, CpG8, CpG9,10,11 of MGMT , CpG11 of HOGG1 ; CpG15,16,17, CpG19 of RAD51, and genetic damage markers including 8-OHdG and micronucleus frequency. Significant negative association between methylation levels of CpG sites in DNA repair genes and corresponding mRNA was also observed in 16HBE cells. This indicated that Cr(VI) exposure can down-regulate DNA repair gene expression by hypermethylation, which leads to enhanced genetic damage. The methylation level of these CpG sites of DNA repair genes can be potential epigenetic markers for Cr(VI)-induced DNA damage. [ABSTRACT FROM AUTHOR]

The purpose of this research is to study the process of mutagenesis and the reproductive function in male rats under separate and combined exposure to chromium and boron compounds. The experiment was conducted on two groups of animals. The first group was used to assess the ability of potassium dichromate and boric acid to induce mutation in germ and somatic cells under isolated and combined administration with the use of the dominant lethal mutations test and the micronuclei test in the polychromatophilic erythrocytes of the bone marrow. The second group was used to test the combined and separate effect of the compounds under consideration on the reproductive function of male rats during the spermatogenesis cycle. When used in specific doses, boron compounds are a promising means of preventing and correcting chromium-induced effects in chromium production facility workers and people who live in ecologically adverse regions. [ABSTRACT FROM AUTHOR]

Chromium (Cr) is one of the most important environmental pollutants which are released into the environment due to their wide usage in numerous industries. The excess of Cr (VI) can induce hepatotoxicity, while the molecular mechanism that is involved in Cr (VI)-induced hepatotoxicity is unclear. We demonstrated the induction of chromium poisoning model in chickens to identify the differentially expressed genes (DEGs), and their functions were analyzed under different physiological and pathological conditions. Histopathological examination and transcriptome data for chromium-poisoned livers and control livers were annotated with Illumina® HiSeq 2000. The histopathological examination in chromium poisoning groups showed diapedesis, hemolysis, degeneration, nucleus pycnosis, and central phlebectasia in the liver. A total of 334 genes were upregulated and 509 genes were downregulated. The most strongly upregulated genes were HKDC1, DDX4, ACACA, FDFT1, CYYR1, PPP1R3C, and SLC16A14, while the most downregulated genes were MYBPC3, CCKAR, PCK1, and CPT1A. A Gene Ontology (GO) term with the highest enrichment of DEGs is small molecule metabolic process. In cell component domain, the term with the highest enrichment is extracellular matrix. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways showed that glucose metabolism, lipid metabolism, and protein metabolism were the most important metabolic pathways in the liver. The current study first time provides important clues and evidence for identifying the differentially expressed genes in livers due to Cr (VI)-induced liver injury in chickens. [ABSTRACT FROM AUTHOR]

Increased wastewater from the batik and textile industries as well as the content of chromium released from the coloring process will negatively affect an aquatic environment. The phytoremediation technique using Vetiver (Chrysopogon zizanioides L.) was applied to treat the wastewater. A hydroponic system with batik wastewater concentrations of 0%, 50%, 75%, and 100% was selected. Each treatment contained six pots, and each pot consisted of three clumps. This study aimed to determine the ability of Chrysopogon zizanioides L. to decrease chromium concentrations and improve water quality parameters (Ammonia, BOD, and COD) and analyze Chrysopogon zizanioides L. growth. On 50% wastewater composition, removal efficiency of chromium was 40%, BOD was 37.95±8.14 mg/L, removal efficiency of BOD was 98.47%, COD was 273.88±24.93 mg/L, and removal efficiency of COD was 89.05%. Relative growth rate (RGR) of plants was 0.002±0.00, and the number of living clumps was nine (50%). The results showed that 50% of batik wastewater can be treated by Chrysopogon zizanioides L. in a hydroponic system. [ABSTRACT FROM AUTHOR]

Chromium (Cr) contamination in arable soils and irrigating water remains a priority, particularly due to the challenges posed to crop production and food safety. Long-term Cr(VI) effects remain less addressed than short-term ones, particularly regarding organ-specific genotoxic profiles. Here we used the crop Lactuca sativa growing in a protected horticultural system and irrigated for 21 days with Cr(VI) (up to 200 mg/L). Besides the oxidative stress, the genotoxicity was evaluated. Shoots and roots showed distinctive oxidative stress status and genotoxic effects, in a dose-dependent manner. While 50 mg/L stimulated antioxidant activities and no major genotoxic effects were found, plants exposed to ≥150 showed an increase of oxidative disorders, together with cytostatic and DNA damage effects, and some mitotic impairment. Leaves showed less oxidative signs at 50 mg/L, while at 150/200 mg/L the antioxidant battery was stimulated. In Cr treated plants, the highest dose increased the DNA damage, reinforcing the idea that DNA breaks were related to mitotic disorders in higher doses. In conclusion, long-term exposure data show a highly responsive root, with a quadratic response meaning higher defenses at lower Cr doses, and higher oxidative and DNA damage and cytostatic effect at a higher dose. [ABSTRACT FROM AUTHOR]

The objective of this work is to detect the mode of damage caused by Cr(III), one of the widely used industrial pollutant on Bacillus subtilis—industrial strain 168 and Escherichia coli MTCC 40. Bioassays are very sensitive, precise, economical and rapid for detecting early stages of pollution. The detrimental effect of trivalent chromium becomes clear from the growth profile and growth inhibition studies. Mode of action of damage by trivalent chromium in bacterial model was found to be oxidative, as chromium is one of the redox active metals. The generation of reactive oxygen species (ROS) resulted in membrane damage which in turn had a detrimental effect on the membrane proteins as well as the DNA. The structural changes in the SEM and AFM images clearly reveals the damage caused by Cr(III) to the test bacterial models. Trivalent chromium causes greater DNA, protein and membrane damage in case of E. coli than B. subtilis. Membrane damage caused by ROS becomes evident from the production of Thiobarbituric acid reactive substances (TBARs) as the mechanism of killing followed by DNA damage and the production of elevated levels of stress proteins known as extracellular cellular proteins. [ABSTRACT FROM AUTHOR]

Chromium poisoning the La 0.875 Sr 0.125 MnO 3 (LSM) cathode for solid oxide fuel cells is a critical issue that can strongly affect the stability. In this study, we evaluate the temperature distribution in a SOFC based on a 3D model and then combine conductivity test and material computation to reveal the effects of chromium in SUS430 stainless steels on LSM conductivities. The starch concentration in LSM pellets and the applied pressure on the contact with interconnect materials show close relationships with the chromium poisoning behavior. The density functional theory (DFT) computing results indicate that chromium atoms preferably adsorb on the MnO 2 -terminated and La (Sr)-O-terminated (001) surfaces. The resulting conclusions are expected to deeply understand mechanism of chromium deactivating conventional cathodes at some typical operational conditions, and offer crucial information to optimize the structure to avoid the poisoning effect. [ABSTRACT FROM AUTHOR]

Chromium is highly toxic and considered as a severe contaminate. Therefore, low cost, highly sensitive sensors for the determination of Cr(vi) are highly required. In the present study, highly luminescent N-doped carbon dots (CG-CDs) obtained from citric acid and glycine with a quantum yield of 78% and label-free fluorescent assay system were designed for Cr(vi) detection based on the inner filter effect (IFE). The CG-CDs were prepared by a one-step hydrothermal method using citric acid and glycine as carbon precursors. The fluorescent sensors showed rapid response, high selectivity, and sensitivity to Cr(vi). A good linear relationship between the concentration of Cr(vi) ions and fluorescence intensity was obtained in the range from 5 to 200 μmol L−1 (R2 = 0.98), and the limit of detection was calculated to be 4.16 μmol L−1 for Cr(vi). Importantly, this method has been successfully applied to the detection of Cr(vi) ions in simulated aquaculture water, which may be helpful to reduce the risk of Cr(vi) intake from contaminated water. [ABSTRACT FROM AUTHOR]

A pot experiment was conducted to determine the effects of varying Cr (VI) levels [0.0-4.0 mg Cr (VI) kg-1 soil in the form of potassium dichromate] on the some quality parameters of sorghum Sorghum bicolor (L.). Quality parameters was measured in terms of protein content, chlorophyll content, and IVDMD (In vitro dry matter digestibility) content at different growth stages, i.e. 35 DAS, 70 DAS and 90 DAS (Days after sowing) that were adversely affected with an increase in Cr (VI) levels from 0.0 to 4.0 mg Cr (VI) kg-1 soil. The decline in protein content 4.67 g/kg dry weight at T4 was observed as compared to control (T1) (8.96 g/kg dry weight basis) at 35 DAS in leaves, Total chlorophyll content declined from 3.25 mg g-1 fresh weight (T1) to 2.40 mg g-1 fresh weight (T4) at 35 DAS and IVDMD content declined from 43.60 to 33.60 per cent dry weight basis with increment in chromium concentration. It is concluded that Cr (VI) at higher doses (4.0 mg Cr (VI) kg-1 soil) adversly affects the quality parameters of Forage sorghum Sorghum bicolor (L.) however, quality parameters are responsible for nutritive value of sorghum Sorghum bicolor (L.). [ABSTRACT FROM AUTHOR]

Cr-poisoning of the cathodes due to the presence of metallic interconnects is detrimental to the performance of intermediate temperature solid oxide fuel cell stacks. Applying a protective coating on the interconnect is an effective solution to preventing Cr-poisoning. In this study, the application of a protective CuMn 1.8 O 4 spinel coating is explored. Dense coatings are deposited on both metallic flat plates and meshes by electrophoretic deposition followed by thermal densification steps. The coating is found to be a mixture of Mn 3 O 4 and cubic spinel phases at room temperature but is a pure cubic spinel phase between 750 °C and 850 °C. A reaction layer between the Cr 2 O 3 scale at the coating/interconnect interface and CuMn 1.8 O 4 coating is found to be a mixture of (Cu,Mn,Cr) 3-x O 4 cubic spinel phases with Cr-rich precipitates believed to be Cr 2 O 3 , indicating that the coating layer acts as a Cr getter. Solubility experiments show that 1 mol of the CuMn 1.8 O 4 phase can getter at least 1.83 mol of Cr 2 O 3 at 800 °C. Electrochemical testing of cells in the presence of coated interconnects show that the CuMn 1.8 O 4 coating getters Cr effectively for 12 days at 800 °C, leading to no performance loss of the cell due to Cr-poisoning. [ABSTRACT FROM AUTHOR]

Chromium (Cr) contamination in soil is a growing concern in sustainable agricultural production and food safety. Remediation of Cr from contaminated soils is a challenging task which may not only help in sustaining agriculture but also in minimizing adverse environmental impacts. Pot culture experiments were performed with the application of varied concentration of Cr +6 to assess the Chromium accumulation potential of Lemongrass and to study the impact of toxic concentration of Cr +6 on morphological, physiological and biochemical parameters of the plant. The results showed an increasing accumulation trend of Chromium with increasing Chromium concentrations in both root and shoot of 60 days old Lemongrass plants, while the protein and chlorophyll contents decreased. Similarly, accumulation of Cr increased the levels of proline and antioxidant enzymes indicating the enhanced damage control activity. The potentiality of the plant with the capacity to accumulate and stabilize Cr compound in Cr contaminated soil by phytoremediation process has been explored in the present investigation. [ABSTRACT FROM AUTHOR]

Cyberlindnera jadinii M9 and Wickerhamomyces anomalus M10 isolated from textile-dye liquid effluents has shown capacity for chromium detoxification via Cr(VI) biological reduction. The aim of the study was to evaluate the effect of hexavalent chromium on synthesis of novel and/or specific proteins involved in chromium tolerance and reduction in response to chromium overload in two indigenous yeasts. A study was carried out following a proteomic approach with W. anomalus M10 and Cy. jadinii M9 strains. For this, proteins extracts belonging to total cell extracts, membranes and mitochondria were analyzed. When Cr(VI) was added to culture medium there was an over-synthesis of 39 proteins involved in different metabolic pathways. In both strains, chromium supplementation changed protein biosynthesis by upregulating proteins involved in stress response, methionine metabolism, energy production, protein degradation and novel oxide-reductase enzymes. Moreover, we observed that Cy. jadinii M9 and W. anomalus M10 displayed ability to activate superoxide dismutase, catalase and chromate reductase activity. Two enzymes from the total cell extracts, type II nitroreductase (Frm2) and flavoprotein wrbA (Ycp4), were identified as possibly responsible for inducing crude chromate-reductase activity in cytoplasm of W. anomalus M10 under chromium overload. In Cy.jadinii M9, mitochondrial Ferredoxine-NADP reductase (Yah1) and membrane FAD flavoprotein (Lpd1) were identified as probably involved in Cr(VI) reduction. To our knowledge, this is the first study proposing chromate reductase activity of these four enzymes in yeast and reporting a relationship between protein synthesis, enzymatic response and chromium biospeciation in Cy. jadinii and W. anomalus . [ABSTRACT FROM AUTHOR]

The Yellow River is the most important water resource in northern China. In the recent past, heavy metal contamination has become severe due to industrial processes and other anthropogenic activities. In this study, riparian soil samples with varying levels of chromium (Cr) pollution severity were collected along the Gansu industrial reach of the Yellow River, including samples from uncontaminated sites (XC, XGU), slightly contaminated sites (LJX, XGD), and heavily contaminated sites (CG, XG). The Cr concentrations of these samples varied from 83.83 mg⋅kg-1 (XGU) to 506.58 mg⋅kg-1 (XG). The chromate [Cr (VI)] reducing ability in the soils collected in this study followed the sequence of the heavily contaminated > slightly contaminated > the un-contaminated. Common Cr remediation genes chrA and yieF were detected in the XG and CG samples. qRT-PCR results showed that the expression of chrA was up-regulated four and threefold in XG and CG samples, respectively, whereas the expression of yieF was up-regulated 66- and 7-fold in the same samples after 30 min treatment with Cr (VI). The copy numbers of chrA and yieF didn’t change after 35 days incubation with Cr (VI). The microbial communities in the Cr contaminated sampling sites were different from those in the uncontaminated samples. Especially, the relative abundances of Firmicutes and Bacteroidetes were higher while Actinobacteria was lower in the contaminated group than uncontaminated group. Further, potential indicator species, related to Cr such as Cr-remediation genera (Geobacter, PSB-M-3, Flavobacterium, and Methanosarcina); the Cr-sensitive genera (Skermanella, Iamia, Arthrobacter, and Candidatus Nitrososphaera) were also identified. These data revealed that Cr shifted microbial composition and function. Further, Cr (VI) reducing ability could be related with the expression of Cr remediation genes. [ABSTRACT FROM AUTHOR]

In the current industrial scenario, chromium (Cr) as a metal is of great importance, but poses a major threat to the environment. Phytoremediation provides an environmentally sustainable, ecofriendly, cost effective approach for environmental cleanup of Cr. This review presents the current status of phytoremediation research with particular emphasis on cleanup of Cr contaminated soil and water systems. It gives a detailed account of the work done by different authors on the Cr bioavailability, uptake pathway, toxicity and storage in plants following the phytoextraction mechanism. This paper also describes recent findings related to Cr localization in hyperaccumulator plants. It gives an insight into the processes and mechanisms that allow plants to remove Cr from contaminated sites under varying conditions. These detailed knowledge of changes in plant metabolic pool in response to Cr stress would immensely help understand and improve the phytoextraction process. Further, this review provides a detailed understanding of Cr uptake and detoxification mechanism by plants that can be applied in developing a suitable approach for a better applicability of the process. [ABSTRACT FROM AUTHOR]

The present study aimed at the potential role of selenium in providing protection to plants subjected to chromium toxicity. The study was carried out on 15-day-old seedlings of Brassica juncea raised in the solutions of Cr (300 µM) and Se (2, 4 and 6 µM), both alone and in combinations under controlled laboratory environment. The effects were studied on growth, plant metabolites (involved in osmotic homeostasis and stress protection), and essential elements. The results showed that the exposure of B. juncea seedlings to 300 µM Cr led to an increase in the contents of total sugars, reducing sugars, non-reducing sugars, total phenols and flavonoids. However, a significant decline in growth characteristics, the contents of proteins and free amino acids was observed. The essential elements (Na, K, Ca, Mg, C, H, N) also decreased in response to Cr. Se application in binary combinations, on the other hand, aided in improving seed germination (19%), root (88.3%) and shoot (18.2%) lengths. It also helped to increase the contents of sugars [total (16.3%), reducing (21.6%) and non-reducing (15.2%)], phenols (36.7%) and flavonoids (27.4%), thereby aiding in alleviating the phytotoxicity of Cr. The profiling of polyphenols and amino acids, and histological study of phenols supported the above results. The contents of essential elements also showed a significant increase, while Cr uptake was observed to decline by Se supplementation. The observations from the present study indicate that Se has the ability to influence primary and secondary metabolism, improve mineral nutrition and reduce Cr uptake in B. juncea seedlings to combat the Cr phytotoxicity and enhance the tolerance against stress. [ABSTRACT FROM AUTHOR]

In the article the sorption ability of microalgae cultures to chromium are discussed. The objects of the study were microalgae from the collection of the Department of Biotechnology of Al-Farabi Kazakh National University, related to cyanoprokaryotes (Cyanoprocaryota/ Cyanobacteria): Anabaena flosaquae, Anabaena arnoldii, Nostoc linckia, Calothrix pariethina as well as their two-species mixtures A. flos-aquae x C. pariethina, N. linckia x C. pariethina, A. flos- aquae x N. Linckia, A. flos-aquae x A. arnoldii and Scenedesmus quadricauda. Also two green (Scenedesmus quadricauda and Chlorhormidium sp.) and one diatomaceous (Nitzshia sp.) algae were studied. The duration of cultivation was 20 days. Potassium bichromate was added to the nutrient medium at concentrations 0.01-0.2 mg/ml calculated per unit of chromium. The concentration of chromium in the filtrates of the studied cultures in some cases significantly decreased by the end of the cultivation period, which indicates the biosorption of this element by the microalgae cells. The investigated strains of microalgae absorb chromium from the medium in varying degrees. The most active biosorbents among the explored cultures were A. flos-aquae, N. linckia and C. pariethina. A microalgae A. arnoldii extracts chromium from the medium in smaller quantities. The listed strains refer to cyanoprokaryotes (cyanobacteria), from other cultures, the Scenedesmus quadricauda absorbs chromium quite actively. The highest intensity of chromium biosorption is characteristic of Nostoc (N. linckia), which extracts from the medium 60.8-74.6% chromium at initial concentrations 0.05-0.1 mg/ ml respectively. The most active biosorbents of chromium were four species of Cyanobacteria. In this regard, these strains have been selected by us for future study of the processes of sorption and metabolic activity in mono- and mixed cultures of microalgae. [ABSTRACT FROM AUTHOR]

Background and aims: Chromium (Cr) toxicity is a rapidly increasing environmental concern and poses a major threat to plant growth as well as food chain. This study was carried out to screen spring wheat diversity panel against Cr toxicity to assess yield reduction, grain contamination extents and genomic regions associated with tolerance to Cr toxicity.Methods: The diversity panel was planted in control and Cr stress (26 mg Cr/kg soil) in paved plots, and several morphological and physiological traits were recorded. Wheat 90 K Infinium iSelect SNP array was used to identify genomic regions underpinning tolerance to Cr toxicity.Results: Some wheat cultivars (Khosar-95, Miraj-08, Millet-11, Sarsabaz and NARC-11) had Cr concentration within international edible threshold limit (1 ppm), but showed greater reduction to grain yield (63–95%) due to higher leaf Cr concentrations (2.35–8.95 ppm). Contrastingly, wheat cultivars Auqab-00 and Pakistan-13 had lower yield reduction up to 9% and 39%, respectively but had higher concentration of Cr in seeds (2.1 and 3.5 ppm, respectively). Genome-wide association studies identified 71 loci linked with yield related traits under Cr stress and 48 loci for differences between control and Cr stress treatments. Further, gene ontology of trait-associated SNPs revealed proteins with significant importance in plant development and tolerance against heavy metal stress.Conclusion: To our knowledge, this is the first study for identification of genomic regions linked to Cr stress, suggesting that this could be useful to identify complex architecture of genetic factors as well as molecular breeding opportunities for tolerance to Cr stress. [ABSTRACT FROM AUTHOR]

Chromium (Cr) as a toxic metal is widely used for commercial purposes and its residues have become a potential environmental threat to both human and plant health. Oilseed rape (Brassica napus L.) is one of the candidate plants that can absorb the considerable quantity of toxic metals from the soil. Here, we used two cultivars of B. napus cvs. ZS 758 (metal-tolerant) and Zheda 622 (metal-susceptible) to investigate the phenological attributes, cell ultrastructure, protein kinases (PKs) and molecular transporters (MTs) under the combined treatments of Cr stress and reduced glutathione (GSH). Seeds of these cultivars were grown in vitro at different treatments i.e., 0, 400μM Cr, and 400μM Cr + 1mM GSH in control growth chamber for 6 days. Results had confirmed that Cr significantly reduced the plant length, stem and root, and fresh biomass such as leaf, stem and root. Cr noticeably caused the damages in leaf mesophyll cells. Exogenous application of GSH significantly recovered both phenological and cell structural damages in two cultivars under Cr stress. For the PKs, transcriptomic data advocated that Cr stress alone significantly increased the gene expressions of BnaA08g16610D, BnaCnng19320D, and BnaA08g00390D over that seen in controls (Ck). These genes encoded both nucleic acid and transition metal ion binding proteins, and protein kinase activity (PKA) and phosphotransferase activities in both cultivars. Similarly, the presence of Cr revealed elite MT genes [BnaA04g26560D, BnaA02g28130D, and BnaA02g01980D (novel)] that were responsible for water transmembrane transporter activity. However, GSH in combination with Cr stress significantly up-regulated the genes for PKs [such as BnaCnng69940D (novel) and BnaC08g49360D] that were related to PKA, signal transduction, and oxidoreductase activities. For MTs, BnaC01g29930D and BnaA07g14320D were responsible for secondary active transmembrane transporter and protein transporter activities that were expressed more in GSH treatment than either Ck or Cr-treated cells. In general, it can be concluded that cultivar ZS 758 is more tolerant toward Cr-induced stress than Zheda 622. [ABSTRACT FROM AUTHOR]

The effect of Cr(VI) as a soil contaminant on the edaphic worm Eisenia andrei was studied by evaluating the activity of Ca 2 + -ATPase in the intestinal mucosa. In eukaryotes, Ca 2 + -ATPase is a key mediator of cell signaling although comparatively little is known about its activity in earthworms. Size and anatomical constraints (i.e. small and complex) led us to develop and optimize a cyto-biochemical method to measure Ca 2 + -ATPase activity in earthworms. The principal site of enzyme activity was found to be the post clitellar intestinal tract; immunohistochemistry then identified plasma membrane Ca 2 + -ATPase (PMCA ATPase) in the apical area of the intestinal epithelium. Earthworms exposed for 28 days to OECD soil contaminated with 1, 2, and 15 mg/Kg Cr(VI) demonstrated about 70% inhibition of Ca 2 + -ATPase activity at the low Cr (VI) concentration (the half of the Italian law limit for residential areas), rising to approximately 84% inhibition at the highest concentration. Reduced enzyme activity was accompanied by decreased enzyme content and reduced lysosomal membrane stability (LMS), which is a well established early warning biomarker of stress. These data demonstrate the potential utility of Ca 2 + -ATPase activity as a sensitive parameter with which to detect environmental stress in earthworms. [ABSTRACT FROM AUTHOR]

Background Nickel (Ni) and chromium (Cr) are components of e-cigarette heating coils. Whether e-cigarettes increase metal internal dose, however, is unknown. We assessed the association of e-cigarette use patterns and of e-liquid and aerosol metal concentrations with Ni and Cr biomarker levels in e-cigarette users from Maryland. Methods We recruited 64 e-cigarette users from December 2015 to March 2016. We collected urine, saliva, and exhaled breath condensate (EBC), data on e-cigarette use, and samples from their e-cigarette device (dispenser e-liquid, aerosol, and tank e-liquid). Results Median Ni and Cr levels were 0.73 and 0.39 μg/g creatinine in urine, 2.25 and 1.53 μg/L in saliva, and 1.25 and 0.29 μg/L in EBC. In adjusted models, tertiles 2 and 3 of aerosol Ni concentrations were associated with 16% and 72% higher urine Ni and 202% and 321% higher saliva Ni compared to the lowest tertile. Tertile 3 of aerosol Cr levels were associated with 193% higher saliva Cr. An earlier time to first vape in the morning and more frequent coil change were associated with higher urine Ni. Tertile 2 of e-liquid consumption per week and voltage were associated with higher saliva Ni levels than tertile 1. Conclusion Positive associations of Ni and Cr aerosol concentrations with corresponding Ni and Cr biomarker levels indicate e-cigarette emissions increase metal internal dose. Increased e-cigarette use and consumption were also associated with higher Ni biomarker levels. Metal level standards are needed to prevent involuntary metal exposure among e-cigarette users. [ABSTRACT FROM AUTHOR]

The extensive use of Cr(VI) in many industries and the disposal of Cr(VI)-containing wastes have resulted in Cr(VI)-induced environmental contamination. Cr(VI) compounds are associated with increased cancer risks; hence, the detection of toxic Cr(VI) compounds is crucial. Various methods have been developed for Cr(VI) measurement, but they are often conducted offsite and cannot provide real-time toxicity monitoring. A microbial fuel cell (MFC) is an eco-friendly and self-sustaining device that has great potential as a biosensor for in situ Cr(VI) measurement, especially for wastewater generated from different electroplating units. In this study, Exiguobacterium aestuarii YC211, a facultatively anaerobic, Cr(VI)-reducing, salt-tolerant, and exoelectrogenic bacterium, was isolated and inoculated into an MFC to evaluate its feasibility as a Cr(VI) biosensor. The Cr(VI) removal efficiency of E. aestuarii YC211 was not affected by the surrounding environment (pH 5-9, 20-35 °C, coexisting ions, and salinity of 0-15 g/L). The maximum power density of the MFC biosensor was 98.3 ۱ 1.5 mW/m2 at 1500 Ω. A good linear relationship (r2 = 0.997) was observed between the Cr(VI) concentration (2.5-60 mg/L) and the voltage output. The developed MFC biosensor is a simple device that can accurately measure Cr(VI) concentrations in the actual electroplating wastewater that is generated from different electroplating units within 30 min with low deviations (-6.1% to 2.2%). After treating the actual electroplating wastewater with the MFC, the predominant family in the biofilm was found to be Bacillaceae (95.3%) and was further identified as the originally inoculated E. aestuarii YC211 by next generation sequencing (NGS). Thus, the MFC biosensor can measure Cr(VI) concentrations in situ in the effluents from different electroplating units, and it can potentially help in preventing the violation of effluent regulations. [ABSTRACT FROM AUTHOR]

In this work, amine riched MnFe 2 O 4 -cellulose was employed to remove toxic Cr (VI). To find out the optimum conditions R (3.3.1) software was used. The results of Cr (VI) adsorption onto three-step adsorbents were compared by interpreting kinetic and isotherm studies. The kinetic studies reveal that the adsorption of Cr (VI) onto cellulose and magnetic cellulose (MC) followed pseudo-first order model whereas the adsorption of Cr (VI) onto amine modified cellulose (AFMC) followed pseudo-second order kinetic model. From the obtained intraparticle diffusion model results it is evident that the adsorption is an external surface process. The adsorption isotherm parameters for Cr (VI) adsorption onto MC and AFMC showed that the correlation coefficient (R 2 : 0.96, 0.88) of Freundlich isotherm is more than that of Langmuir isotherm (R 2 : 0.50, 0.76); hence, it is suggested that the adsorption of Cr (VI) onto these sorbents occurs in multilayer possessing heterogeneous sorption sites whereas the adsorption onto cellulose followed Langmuir model. The maximum adsorption capacities of cellulose, MC and AFMC under optimum conditions were found to be 25, 125 and 250 mg/g, respectively; thus, it is confirmed that adsorption efficiency has been improved after modification steps. [ABSTRACT FROM AUTHOR]

The effect of hydro-alcoholic extract of Curculigo orchoides on hexavalent chromium (Cr VI) induced toxicity in rats was investigated. Sub-acute toxicity studies were performed by OECD guidelines. K 2 Cr 2 O 7 (30 mg/kg) was administered to all groups except control group for a period of 28 days by oral gavage. Control group received distilled water; treatment groups received C. orchoides (25, 50 and 100 mg/kg). Cr(VI) administration resulted in up-regulation of serum biochemical parameters such as alanine transaminase, aspartate transaminase, alkaline phosphatase, and tissue biochemical markers viz. lipid peroxidation and protein carbonyl content. C. orchioides (100 mg/kg) significantly decreased these enzyme levels. The activities of anti-oxidant enzymes like superoxide dismutase, catalase and glutathione S-transferase were significantly decreased by Cr(VI) administration (50.7%, 43.7% and 37.9%, respectively). Further, mRNA expression studies and histopathology studies confirmed Cr(VI) toxicity. In all cases, C. orchioides promoted significant restoration of enzyme levels in a dose dependent manner. These results suggest the ameliorating effect of C. orchoides on Cr(VI) induced oxidative stress is probably via , modulation of cytokines, transcription factors and apoptotic genes. [ABSTRACT FROM AUTHOR]

The determination of whether a chemical induces a specific cancer through a mutagenic or non-mutagenic mode of action (MOA) plays an important role in choosing between linear and nonlinear low-dose extrapolation to derive toxicity criteria. There is no formal framework from the U.S. EPA for determining whether environmental chemicals act through a mutagenic or non-mutagenic MOA; consequently, most such determinations are made on an ad hoc basis. Eastmond [Mutat Res 751 (2012)] recently conducted a systematic investigation of MOA determinations by U.S. and international regulatory agencies and organizations, and identified ten major factors that influence them, including toxicokinetics, in vivo genotoxicity in target organs, data quality, and evidence for alternative MOAs. We have used these ten factors to evaluate mutagenic vs . non-mutagenic MOA for gastrointestinal tumors induced by oral exposure to hexavalent chromium [Cr(VI)]. We also highlight similarities between Cr(VI) and other intestinal carcinogens previously determined to have non-genotoxic MOAs. Based on these analyses, we conclude that the MOA for Cr(VI) induced gastrointestinal tumors is non-mutagenic and that threshold risk assessment approaches are appropriate. [ABSTRACT FROM AUTHOR]

Chromium exposure from increasing industrial releases has become a threat for pregnant women due to the potential health effects on vulnerable embryos. Previous studies have suggested that maternal chromium exposure is associated with adverse birth outcomes, but no epidemiological research has been conducted to examine the relationship between chromium exposure and premature rupture of membranes (PROM). This study aimed at investigating the association of maternal urinary chromium exposure levels with PROM and was performed with 5408 pregnant women recruited from 2012 to 2014 in the city of Wuhan, China. Maternal urinary chromium collected before labor was adjusted with creatinine, and its association with PROM was evaluated using logistic regression. Each one unit increase in the natural logarithm transformed maternal urinary chromium concentration (μg/g creatinine), an odds ratio (OR) of 1.47 [95% confidence interval (CI): 1.36, 1.58] for PROM was observed. Compared to the lowest tertile of maternal urinary chromium, PROM was positively correlated with increased urinary levels of chromium (adjusted OR = 1.42; 95% CI: 1.09, 1.84 for the medium tertile; adjusted OR = 2.77; 95% CI: 2.18, 3.52 for the highest tertile). Additionally, the association of chromium with PROM appeared to be more significant among male infants (adjusted OR = 3.52; 95% CI: 2.51, 4.94 for the highest tertile) than female infants (adjusted OR = 2.16; 95% CI: 1.52, 3.06 for the highest tertile) ( p for interaction = 0.05). Our large birth cohort showed an association between maternal urinary chromium levels and PROM, and the association may differ by infant gender. Further studies from different populations are needed to confirm the observed association. [ABSTRACT FROM AUTHOR]

Chromium (Cr) is a common pollutant of freshwater bodies in India, and is frequently detected in high concentrations in edible fish. Bioassays were carried out in the laboratory to determine acute the toxicity and pattern of accumulation of Cr in three species of freshwater fish. The 96-h LC50value of Cr forLabeo bata, Puntius sarana, andCatla catlawas found respectively as 7.33, 10.37, and 31.61 mg/L. Concentrations of Cr in water, sediments, and fish, during a period of 28 d of exposure to 0, 0.73, and 2.19 mg/L of Cr, varied with exposure period, concentration of Cr, presence of weed, and species of fish exposed. Polynomial regressions obtained by drawing polynomial curves revealed that the aquatic weedEichhornia crassipesprevented gradual decrease of Cr concentrations in water, but reduced the accumulation of Cr inL. bataandCatla catla. However, the effect of the weed onPuntius saranawas not apparent. The pattern of Cr deposition on sediments was also inconsistent. To explain interactions between environment and fish in a very precise manner, polynomial and multiple regression curves were simultaneously used. When polynomial curves were replaced by multiple regression curves, it was revealed that the aquatic weedE. crassipescould reduce Cr accumulation inPuntius saranaalso. [ABSTRACT FROM AUTHOR]

Inhalation of soluble chromium(VI) is firmly linked with higher risks of lung cancer in humans. However, comparative studies in rats have found a high lung tumorigenicity for moderately soluble chromates but no tumors for highly soluble chromates. These major species differences remain unexplained. We investigated the impact of extracellular reducers on responses of human and rat lung epithelial cells to different Cr(VI) forms. Extracellular reduction of Cr(VI) is a detoxification process, and rat and human lung lining fluids contain different concentrations of ascorbate and glutathione. We found that reduction of chromate anions in simulated lung fluids was principally driven by ascorbate with only minimal contribution from glutathione. The addition of 500 μM ascorbate (∼rat lung fluid concentration) to culture media strongly inhibited cellular uptake of chromate anions and completely prevented their cytotoxicity even at otherwise lethal doses. While proportionally less effective, 50 μM extracellular ascorbate (∼human lung fluid concentration) also decreased uptake of chromate anions and their cytotoxicity. In comparison to chromate anions, uptake and cytotoxicity of respirable particles of moderately soluble CaCrO4 and SrCrO4 were much less sensitive to suppression by extracellular ascorbate, especially during early exposure times and in primary bronchial cells. In the absence of extracellular ascorbate, chromate anions and CaCrO4/SrCrO4 particles produced overall similar levels of DNA double-stranded breaks, with less soluble particles exhibiting a slower rate of breakage. Our results indicate that a gradual extracellular dissolution and a rapid internalization of calcium chromate and strontium chromate particles makes them resistant to detoxification outside the cells, which is extremely effective for chromate anions in the rat lung fluid. The detoxification potential of the human lung fluid is significant but much lower and insufficient to provide a threshold-type dose dependence for soluble chromates. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cell (SOFC) systems provide efficient and clean power. Chromium poisoning is known to deteriorate the performance of the SOFC cathodes such as La 1−x Sr x CoO 3 (LSCO) due to the formation of undesired products. We identify the reaction products when LSCO is in a CrO 3 and O 2 atmosphere using first principle thermodynamics, with the assumption that gas-phase CrO 3 is the Cr source. Our results correctly identify SrCrO 4 as the primary Cr poisoning product as observed in experiments and also provides temperature-pressure regimes under which Cr poisoning effects may be avoided. [ABSTRACT FROM AUTHOR]