Hexavalent chromium
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There is limited evidence regarding the exposure-effect relationship between lung-cancer risk and hexavalent chromium (Cr(VI)) or nickel. We estimated lung-cancer risks in relation to quantitative indices of occupational exposure to Cr(VI) and nickel and their interaction with smoking habits. We pooled 14 case-control studies from Europe and Canada, including 16 901 lung-cancer cases and 20 965 control subjects. A measurement-based job-exposure-matrix estimated job-year-region specific exposure levels to Cr(VI) and nickel, which were linked to the subjects' occupational histories. Odds ratios (OR) and associated 95% confidence intervals (CI) were calculated by unconditional logistic regression, adjusting for study, age group, smoking habits and exposure to other occupational lung carcinogens. Due to their high correlation, we refrained from mutually adjusting for Cr(VI) and nickel independently. In men, ORs for the highest quartile of cumulative exposure to CR(VI) were 1.32 (95% CI 1.19-1.47) and 1.29 (95% CI 1.15-1.45) in relation to nickel. Analogous results among women were: 1.04 (95% CI 0.48-2.24) and 1.29 (95% CI 0.60-2.86), respectively. In men, excess lung-cancer risks due to occupational Cr(VI) and nickel exposure were also observed in each stratum of never, former and current smokers. Joint effects of Cr(VI) and nickel with smoking were in general greater than additive, but not different from multiplicative. In summary, relatively low cumulative levels of occupational exposure to Cr(VI) and nickel were associated with increased ORs for lung cancer, particularly in men. However, we cannot rule out a combined classical measurement and Berkson-type of error structure, which may cause differential bias of risk estimates.
- MeSH
- chrom toxicita analýza MeSH
- lidé MeSH
- nádory plic * chemicky indukované epidemiologie MeSH
- nikl toxicita analýza MeSH
- pracovní expozice * škodlivé účinky analýza MeSH
- studie případů a kontrol MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- metaanalýza MeSH
Human biomonitoring (HBM) studies have highlighted widespread daily exposure to environmental chemicals. Some of these are suspected to contribute to adverse health outcomes such as reproductive, neurological, and metabolic disorders, among other developmental and chronic impairments. One of the objectives of the H2020 European Human Biomonitoring Initiative (HBM4EU) was the development of informative effect biomarkers for application in a more systematic and harmonized way in large-scale European HBM studies. The inclusion of effect biomarkers would complement exposure data with mechanistically-based information on early and late adverse effects. For this purpose, a stepwise strategy was developed to identify and implement a panel of validated effect biomarkers in European HBM studies. This work offers an overview of the complete procedure followed, from comprehensive literature search strategies, selection of criteria for effect biomarkers and their classification and prioritization, based on toxicological data and adverse outcomes, to pilot studies for their analytical, physiological, and epidemiological validation. We present the example of one study that demonstrated the mediating role of the effect biomarker status of brain-derived neurotrophic factor BDNF in the longitudinal association between infant bisphenol A (BPA) exposure and behavioral function in adolescence. A panel of effect biomarkers has been implemented in the HBM4EU Aligned Studies as main outcomes, including traditional oxidative stress, reproductive, and thyroid hormone biomarkers. Novel biomarkers of effect, such as DNA methylation status of BDNF and kisspeptin (KISS) genes were also evaluated as molecular markers of neurological and reproductive health, respectively. A panel of effect biomarkers has also been applied in HBM4EU occupational studies, such as micronucleus analysis in lymphocytes and reticulocytes, whole blood comet assay, and malondialdehyde, 8-oxo-2'-deoxyguanosine and untargeted metabolomic profile in urine, to investigate, for example, biological changes in response to hexavalent chromium Cr(VI) exposure. The use of effect biomarkers in HBM4EU has demonstrated their ability to detect early biological effects of chemical exposure and to identify subgroups that are at higher risk. The roadmap developed in HBM4EU confirms the utility of effect biomarkers, and support one of the main objectives of HBM research, which is to link exposure biomarkers to mechanistically validated effect and susceptibility biomarkers in order to better understand the public health implications of human exposure to environmental chemicals.
Laser ablation in liquid (LAL), one of the attractive methods for fabrication of nanoparticles, was used for the modification of carbon cloth (CC) by deposition of palladium nanoparticles (Pd NPs); a simple stirring method was deployed to deposit Pd NPs on the CC surface. Characterization techniques viz X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) were applied to study the surface of the ensuing samples which confirmed that LAL technique managed to fabricate and deposit the Pd NPs on the surface of CC. In addition, the catalytic prowess of the carbon cloth-Pd NPs (CC/Pd NPs) was investigated in the NaBH4- or HCOOH-assisted reduction of assorted environmental pollutants in aqueous medium namely hexavalent chromium [Cr(VI)], 4-nitrophenol (4-NP), congo red (CR) and methylene blue (MB). The CC/Pd NPs system has advantages such as high stability/sustainability, high catalytic performance and easy reusability.
- MeSH
- chemické látky znečišťující vodu analýza chemie MeSH
- chrom MeSH
- katalýza MeSH
- Kongo červeň MeSH
- kovové nanočástice chemie MeSH
- lasery MeSH
- methylenová modř chemie MeSH
- nitrofenoly MeSH
- palladium chemie MeSH
- spektrometrie rentgenová emisní MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- textilie MeSH
- uhlík MeSH
- Publikační typ
- časopisecké články MeSH
This study analysed the effect of three alkalizing soil amendments (limestone, dolomite chalcedonite) on aided phytostabilization with Festuca rubra L. depending on the hexavalent chromium (Cr(VI)) level in contaminated soil. Four different levels of Cr(VI) were added to the soil (0, 50, 100 and 150 mg/kg). The Cr contents in the plant roots and above-ground parts and the soil (total and extracted Cr by 0.01 M CaCl2) were determined with flame atomic absorption spectrometry. The phytotoxicity of the soil was also determined. Soil amended with chalcedonite significantly increased F. rubra biomass. Chalcedonite and limestone favored a considerable accumulation of Cr in the roots. The application of dolomite and limestone to soil contaminated with Cr(VI) contributed to a significant increase in pH values and was found to be the most effective in reducing total Cr and CaCl2-extracted Cr contents from the soil. F. rubra in combination with a chalcedonite amendment appears to be a promising solution for phytostabilization of Cr(VI)-contaminated areas. The use of this model can contribute to reducing human exposure to Cr(VI) and its associated health risks.
The release of hexavalent chromium [Cr (VI)] into environments has resulted in many undesirable interactions with biological systems for its toxic potential and mutagenicity. Chromate reduction via chromium reductase (ChrR) is a key strategy for detoxifying Cr (VI) to trivalent species of no toxicity. In this study, ten bacterial isolates were isolated from heavily polluted soils, with a strain assigned as FACU, being the most efficient one able to reduce Cr (VI). FACU was identified as Escherichia coli based on morphological and 16S rRNA sequence analyses. Growth parameters and enzymatic actions of FACU were tested under different experimental conditions, in the presence of toxic chromium species. The E. coli FACU was able to reduce chromate at 100 μg/mL conceivably by reducing Cr (VI) into the less harmful Cr (III). Two distinctive optical spectroscopic techniques have been employed throughout the study. Laser-induced breakdown spectroscopy (LIBS) was utilized as qualitative analysis to demonstrate the presence of chromium with the distinctive spectral lines for bacteria such as Ca, Fe, and Na. While UV-visible spectroscopy was incorporated to confirm the reduction capabilities of E. coli after comparing Cr (III) spectrum to that of bacterial product spectrum and they were found to be identical. The chromate reductase specific activity was 361.33 μmol/L of Cr (VI) per min per mg protein. The FACU (EMCC 2289) 16S rRNA sequence and the ChrR-partially isolated gene were submitted to the DDBJ under acc. # numbers LC177419 and LC179020, respectively. The results support that FACU is a promising source of ChrR capable of bioremediation of toxic chromium species.
- MeSH
- bakteriální léková rezistence MeSH
- biodegradace MeSH
- chrom metabolismus farmakologie MeSH
- Escherichia coli klasifikace izolace a purifikace metabolismus fyziologie MeSH
- fylogeneze MeSH
- karcinogeny životního prostředí metabolismus farmakologie MeSH
- oxidace-redukce MeSH
- oxidoreduktasy genetika metabolismus MeSH
- proteiny z Escherichia coli genetika metabolismus MeSH
- půdní mikrobiologie MeSH
- RNA ribozomální 16S genetika MeSH
- Publikační typ
- časopisecké články MeSH
This paper deals with the problem of chromium recovery from chrome-tanned waste and thus with reducing the environmental impact of the leather industry. Chrome-tanned waste was transformed by alkaline enzymatic hydrolysis promoted by magnesium oxide into practically chromium-free, commercially applicable collagen hydrolysate and filtration cake containing a high portion of chromium. The crude and magnesium-deprived chromium cakes were subjected to a process of thermal decomposition at 650°C under oxygen-free conditions to reduce the amount of this waste and to study the effect of magnesium removal on the resulting products. Oxygen-free conditions were applied in order to prevent the oxidation of trivalent chromium into the hazardous hexavalent form. Thermal decomposition products from both crude and magnesium-deprived chrome cakes were characterized by high chromium content over 50%, which occurred as eskolaite (Cr2O3) and magnesiochromite (MgCr2O4) crystal phases, respectively. Thermal decomposition decreased the amount of chrome cake dry feed by 90%. Based on the performed experiments, a scheme for the total control of chromium in the leather industry was designed.
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. K2Cr2O7 (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.
- Klíčová slova
- Curculigo orchoides,
- MeSH
- antioxidancia farmakologie terapeutické užití MeSH
- chrom * toxicita MeSH
- Curculigo * MeSH
- dvojchroman draselný toxicita MeSH
- histologické techniky MeSH
- krysa rodu rattus MeSH
- oxidační stres účinky léků MeSH
- polymerázová řetězová reakce MeSH
- potkani Wistar MeSH
- rostlinné extrakty * farmakologie terapeutické užití MeSH
- stanovení celkové genové exprese MeSH
- testy toxicity metody statistika a číselné údaje MeSH
- western blotting MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
Chromium-enriched diamond-like carbon (DLC) layers were prepared by a hybrid technology using a combination of pulsed laser deposition (PLD) and magnetron sputtering. XRD revealed no chromium peaks, indicating that the layers are mostly amorphous. Carbon (sp(2) and sp(3) bonds) and chromium bonds were determined by XPS from C 1s, O 1s, and Cr 2p photoelectron peaks. Depending on the deposition conditions, the concentration of Cr in DLC layers moved from zero to 10 at.% for as-received sample surfaces, and to about 31 at.% after mild sputter-cleaning by argon ion cluster beam. It should be noted that the most stable Cr(3+) bonding state is in Cr2O3 and Cr(OH)3, and that there is the toxic Cr(6+) state in CrO3. The surface content of hexavalent chromium in the Cr 2p3/2 spectra is rather low, but discernible. The population density of Saos-2 cells was the highest in samples containing higher concentrations of chromium 7.7 and 10 at.%. This means that higher concentrations of chromium supported the cell adhesion and proliferation. In addition, as revealed by a LIVE/DEAD viability/cytotoxicity kit, the cells on all Cr-containing samples maintained high viability (96 to 99%) on days 1 and 3 after seeding. However, this seemingly positive cell behavior could be associated with the risk of dedifferentiation and oncogenic transformation of cells.
- MeSH
- biokompatibilní materiály chemie toxicita MeSH
- chrom chemie MeSH
- diamant chemie MeSH
- lasery MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- viabilita buněk účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Diamond-like carbon (DLC) thin films are frequently used for coating of implants. The problem of DLC layers lies in bad layer adhesion to metal implants. Chromium is used as a dopant for improvement of adhesion of DLC films. DLC and Cr-DLC layers were deposited on silicon, Ti6Al4V and CoCrMo substrates by a hybrid technology using combination of pulsed laser deposition (PLD) and magnetron sputtering. The topology of layers was studied using SEM, AFM and mechanical profilometer. Carbon and chromium content and concentration of trivalent and toxic hexavalent chromium bonds were determined by XPS and WDS. It follows from the scratch tests that Cr doping improved adhesion of DLC layers. Ethylene glycol, diiodomethane and deionized water were used to measure the contact angles. The surface free energy (SFE) was calculated. The antibacterial properties were studied using Pseudomonas aeruginosa and Staphylococcus aureus bacteria. The influence of SFE, hydrophobicity and surface roughness on antibacterial ability of doped layers is discussed.
