Showing papers on "Potassium dichromate published in 2000"

A comparison of the in vitro genotoxicity of tri- and hexavalent chromium.

Abstract: Chromium can be found in the environment in two main valence states: hexavalent (Cr(VI)) and trivalent (Cr(III)). Cr(VI) salts are well known human carcinogens, but the results from in vitro studies are often conflicting. Cr(VI) primarily enters the cells and undergoes metabolic reduction; however, the ultimate product of this reduction, Cr(III) predominates within the cell. In the present work, we compared the effects of tri- and hexavalent chromium on the DNA damage and repair in human lymphocytes using the alkaline single cell gel electrophoresis (comet assay). Potassium dichromate induced DNA damage in the lymphocytes, measured as the increase in comet tail moment. The effect was dose-dependent. Treated cells were able to recover within a 120-min incubation. Cr(III) caused greater DNA migration than Cr(VI). The lymphocytes did not show measurable DNA repair. Vitamin C at 50 μM reduced the extent of DNA migration. This was either due to a decrease in DNA strand breaks and/or alkali labile sites induced by Cr(VI) or to the formation of DNA crosslinks by Cr(VI) in the presence of vitamin C. Vitamin C, however, did not modify the effects of Cr(III). Catalase, an enzyme inactivating hydrogen peroxide, decreased the extent of DNA damage induced by Cr(VI) but not the one induced by Cr(III). Lymphocytes exposed to Cr(VI) and treated with endonuclease III, which recognizes oxidized pyrimidines, displayed greater extent of DNA damage than those not treated with the enzyme. Such an effect was not observed when Cr(III) was tested. The results obtained suggest that reactive oxygen species and hydrogen peroxide may be involved in the formation of DNA lesions by hexavalent chromium. The comet assay did not indicate the involvement of oxidative mechanisms in the DNA-damaging activity of trivalent chromium and we speculate that its binding to cellular ligands may play a role in its genotoxicity.

Hexavalent chromium reduction by a dichromate-resistant gram-positive bacterium isolated from effluents of tanneries.

Abstract: A gram-positive, chromium (Cr)-resistant bacterial strain (ATCC 700729) was isolated from effluent of tanneries. It was grown in media containing potassium dichromate concentration up to 80 mg ml−1 of the medium. The dichromate reducing capability of the bacterium was checked by estimating the amount of Cr VI in the medium before and after introduction of bacterial culture. The influence of factors like pH of the medium, concentration of Cr, and the amount of the inoculum was studied to determine the ability of the bacterium to reduce Cr VI in the medium under various conditions. In a medium containing dichromate 20 mg ml−1 more than 87% reduction of dichromate ions was achieved within 72 h. The feasibility of the use of this bacterial strain for detoxification of dichromate in the industrial wastewater has been assessed. The isolated strain can be exploited for specific environmental clean-up operations.

Effects of physical (hypoxia, hyperoxia) and chemical (potassium dichromate, fenitrothion) stress on antioxidant enzyme activities in Chironomus riparius mg. (diptera, chironomidae) larvae: Potential biomarkers

Abstract: Effects of physical (hypoxia, hyperoxia) and chemical (potassium dichromate, fenitrothion) stress on antioxidant enzyme activities and hemoglobin content in Chironomus riparius Mg. (Diptera, Chironomidae) larvae were evaluated under laboratory conditions in order to identify pertinent biomarkers of stress. Hypoxia and hyperoxia caused an increase in Cu,Zn-superoxide dismutase (SOD) and Mn-SOD activities and a simultaneous decrease in total peroxidase (Px) and glutathione peroxidase (GSH-Px) activities. A parallel increase in hemoglobin concentration in the hemolymph was observed. The exposure to sublethal concentrations of both potassium dichromate and fenitrothion led to an increase in Cu,Zn-SOD and Mn-SOD activities and to a decrease in GSH-Px activity. Activation of catalase (CAT) was observed in the larvae exposed to high fenitrothion concentration (20 micrograms/L). The response of SODs was rapid and sensitive to low chemical concentrations, but changes in CAT, Px, and GSH-Px were more specific and less sensitive.

Gas-generating agent composition

Abstract: PROBLEM TO BE SOLVED: To obtain a composition capable of maintaining a high gas generation efficiency and good in thermal stability and combustibility by including a phase- stabilized ammonium nitrate, nitroguanidine and an oxygen-containing potassium salt and regulating the content of the phase-stabilized ammonium nitrate to a specific value or below. SOLUTION: The content of a phase-stabilized ammonium nitrate is <=45 wt.% and an oxygen-containing potassium salt is at least one kind selected from potassium nitrate, potassium perchlorate, potassium sulfate, potassium chlorate, potassium chromate and potassium dichromate, etc. An inorganic or an organic binder for forming or both in, an amount of <=10 wt.% are contained therein. Specifically, polyethylene glycol, polypropylene glycol, polyvinyl ether, etc., are cited. The content of nitroguanidine used as a reducing agent (a fuel) and having a high gas generation efficiency and a low combustion temperature in the composition is within the range of 35-75 wt.%.

Genotoxicity of chromium in human gastric mucosa cells and peripheral blood lymphocytes evaluated by the single cell gel electrophoresis (comet assay).

Abstract: Hexavalent chromium compounds are well-recognized carcinogens. They easily penetrate the cell membrane and are reduced inside the cell to their trivalent form, which is supposed to react directly with DNA. Chromium is present in some workplaces as well as in water resources and food chain, so it can interact with the mucosa of the gastrointestinal tract. In order to elucidate the genotoxic potency of chromium in human gastric mucosa (GM) cells, the DNA-damaging effect of potassium dichromate (K2Cr2O7) was investigated using alkaline single cell gel electrophoresis (comet assay). Biopsy samples were obtained during gastroscopy from macroscopically healthy tissue of the stomach. Parallel test with human peripheral blood lymphocytes was also performed. Both types of cells were incubated at 37 degrees C with 1.6 mM of K2Cr2O7 for 1 h and after washing, were placed in a chromium-free medium to examine DNA repair. Alkaline single cell gel electrophoresis (comet assay) was used to assess DNA damage and repair. Chromium introduced a damage to DNA both in the GM cells and lymphocytes. The effect induced by K2Cr2O7 in GM cells was comparable with that caused in the lymphocytes. Treated cells were able to recover within a 60-min incubation in a chromium-free medium at 37 degrees C. The results obtained indicate that hexavalent chromium compounds, which may be found in the diet, can interact directly with DNA of the mucosa of the stomach.

Less than additive interaction between cigarette smoke and chromium(VI) in inducing clastogenic damage in rodents.

Abstract: A combination of tobacco smoking with certain agents has been shown to exert synergistic carcinogenic effects. On the other hand, antagonism betweeen smoke and other pulmonary carcinogens has also been documented by both epidemiological and experimental data. In spite of a very large number of studies carried out for decades in workers exposed to hexavalent chromium, the influence of smoking habits on lung carcinogenesis induced by this metal has not been clarified. For this reason, we performed two studies evaluating clastogenic effects in rodents. In the first one, BDF(1) mice were exposed whole-body to mainstream cigarette smoke for 5 days and, on the last day, they received an i.p. injection of potassium dichromate. In the second study, Sprague-Dawley rats were exposed whole-body to environmental cigarette smoke for 18 consecutive days and for the same period of time they received daily intra-tracheal instillations of sodium dichromate. Individually, the two hexavalent chromium salts and cigarette smoke, either mainstream or environmental, enhanced the frequency of micronuclei in bone marrow polychromatic erythrocytes of both mice and rats. Moreover, individual exposure to either environmental cigarette smoke or sodium dichromate enhanced the frequency of micronuclei and multiple nuclei in pulmonary alveolar macrophages of rats. In both studies, combined exposure to cigarette smoke and hexavalent chromium produced less than additive clastogenic effects. These results are consistent with our previous data, showing that hexavalent chromium and either benzo[a]pyrene or cigarette smoke condensate behave antagonistically in in vitro mutagenicity test systems and that the chromium reducing capacity of human pulmonary alveolar macrophages and peripheral lung parenchyma is enhanced in smokers. Taken together, in the absence of any epidemiological evidence, these findings rule out any occurrence of synergism between cigarette smoke and hexavalent chromium, at least in certain stages of the carcinogenesis process.

Chromium(VI)-induced mutagenesis in the lungs of big blue transgenic mice.

Abstract: The mutagenic activity of the hexavalent chromium [Cr(VI)] compound potassium dichromate was examined in the Big Blue transgenic mouse lung, the target organ for Cr(VI) carcinogenesis in humans. Mice were exposed to Cr(VI) by intratracheal instillation of a potassium dichromate (K 2 Cr 2 O 7 ) solution. Analysis of the deposition of Cr in mouse lungs revealed that the procedure reproducibly resulted in about 5% retention of the Cr in the lung. Lower but measurable levels were detected in kidney and liver. We found a dose-dependent and time-dependent increase in the mutant frequency in the mouse lung. A significant elevation of the mutant frequency above the spontaneous background was observed two weeks after Cr(VI) intratracheal instillation and at doses above 3 mg/kg. Depletion of tissue glutathione (GSH) levels by buthionine sulfoximine (BSO) before Cr(VI) treatment led to a decrease in the Cr(VI)-induced mutant frequency, compared to that in the animals with normal GSH levels, suggesting a role for GSH in the generation of reactive intermediates during the intracellular reduction of Cr(VI). Sequence analysis for the Cr(VI)-induced mutants revealed a similarity to the spontaneous mutational spectrum observed in mouse lungs, consistent with the generation of oxidative-type DNA damage by Cr(VI). These results demonstrate that Cr(VI) is mutagenic in mouse lung, the target organ for human carcinogenesis.

Successful treatment of a patient suffering from severe acute potassium dichromate poisoning with liver transplantation.

Abstract: BACKGROUND: Oral ingestion of potassium dichromate produces a complex spectrum of complications. It has an extremely poor prognosis and usually leads to rapid death. METHODS: We report the case of a 16-year-old male patient who was admitted to hospital after oral ingestion of potassium dichromate with suicidal intention. RESULTS: The patient's condition deteriorated, and he became comatose within 5 days in spite of immediate attempts at detoxification. Because of irreversible liver failure, which occurred within 2 days after admission, and because of cerebral edema, the decision to perform a liver transplantation was made. On day 6 after admission, a compatible donor liver was transplanted. The course of liver transplantation and the patient's subsequent recovery were uneventful. CONCLUSION: The rationale for the delayed transplantation was to avoid damage of the new organ because of high serum chromium levels. Despite severe organ damage, the chromium content of the liver was increased. To the authors' knowledge, this is the first case report of acute toxic liver failure, caused by potassium dichromate poisoning, treated successfully by means of liver transplantation. Language: en

Contact allergy to dichromate in women

Abstract: During the years 1993 to 1997, positive reactions to potassium dichromate in men registered in the Information Network of Departments of Dermatology (IVDK. Informationsverbund Dermatologischer Kliniken) in Germany declined from 5.8 % to 4.0 %. The sensitization rate among women remained stable at about 3.6 %. Altogether, 28 577 women were patch tested with potassium dichromate 0.5 % pet. Of these, 1024 (3.6 %) showed a positive reaction at day 3. Among women with positive reaction to potassium dichromate, the feet and the hands were much more often affected than in patients not reacting to dichromate (9.9 VS. 1.7 % and 33.7 vs. 25.8 %, respectively). The analysis of concomitant sensitizations revealed that obviously the source of dichromate sensitization in women with foot dermatitis is chrome tanned shoe leather. Although several more or less certain dichromate sources are described in the literature, the relevant exposure leading to dichromate sensitization in women with hand eczema remains unclear in most cases. Co-sensitization to cobalt without nickel allergy occurs remarkably often among women with dichromate allergy, The source of cobalt allergy mostly remains unclear, too. So, further exposure analysis for dichromate and for cobalt is necessary. A confounding of the patch test results by atopy could be excluded largely.

Effect of a catalyst on the kinetics of reduction of celestite (SrSO4) by active charcoal

Abstract: Reduction of celestite (SrSO4) powder with particles of active charcoal has been studied extensively in the absence and presence of catalysts. The optimum temperature at the charging zone has been optimized to get a maximum water-soluble strontium sulfide value. The strontium value has been analyzed using a chemical method, which was verified by the instrumental method using an inductively coupled plasma-optical emission spectrophotometer (ICP-OES). The conversion-time data have been analyzed by using a modified volume-reaction (MVR) model, and the effect of the catalyst on kinetic parameters has been elucidated. It was found that potassium carbonate, potassium dichromate, sodium carbonate, and sodium dichromate catalysts were found to enhance the reaction rate quite satisfactorily in the reduction of the celestite (SrSO4).

Morphological Diversity in the Crystal Growth of Potassium and Rubidium Dichromates in Gelatin Gel

Abstract: We have found that the crystals of rubidium dichromate (Rb 2 Cr 2 O 7 ) grown in gelatin gel have a rich variety of morphologies such as platelike, spherulitic and diffusion-limited aggregation (DLA)-like shapes. The morphological diagram has been determined in the range of solute and gelatin concentrations from 1.0 to 4.0%, 0.1 to 7.0%, respectively. The diagram corresponds to that of potassium dichromate (K 2 Cr 2 O 7 ) which is similar to Rb 2 Cr 2 O 7 in the crystal structure and physico-chemical properties. However, featherlike crystals have grown in the region of the diagram where the unique helical K 2 Cr 2 O 7 crystals grow. We discuss the morphological changes of two kinds of dichromate crystals grown in gelatin gel.

Mechanisms involved in the induction of aneuploidy: the significance of chromosome loss

Abstract: The induction of aneuploidy by physical and chemical agents using different test systems was evaluated. The effect of X-rays, caffeine, acetaldehyde, ethanol, diethylstilbestrol, propionaldehyde, and chloral hydrate was studied by chromosome counting in Chinese hamster embryonic diploid cells. Aneugenic ability of cadmium chloride, cadmium sulfate, potassium dichromate, chromium chloride, nickel chloride, and nickel sulfate was assessed by means of anaphase-telophase analysis in Chinese hamster ovary cells. Chromosome counting in human fibroblasts (MRC-5 cell line) was employed to evaluate the effect of cacodilic acid, cadmium chloride, cadmium sulfate, and potassium dichromate. Finally, the induction of kinetochore-positive and kinetochore negative micronuclei by cadmium chloride, cadmium sulfate, potassium dichromate, chromium chloride, and nickel chloride was studied using CREST antibodies. When the effect of different agents was determined by chromosome counting, an increase of hypoploid but not of hyperploid cells was observed. Anaphase-telophase analysis showed that metal salts increased the frequency of lagging chromosomes. This finding has been confirmed by the increment of kinetochore-positive micronuclei using CREST antibodies. Therefore, chromosome loss could be considered as the main cause of induced aneuploidy.

Positive nickel patch tests do not intensify positive reactions to adjacent patch tests with dichromate

Abstract: The possible interference of neighbouring allergic patch-test reactions is still an open question. In this study, we investigated whether there is a distance-related mutual modification of neighbouring allergic patch-test reactions to nickel sulfate and potassium dichromate. We used a double-blind multicentre study design with randomized attachment of special TRUE Tests with 1, 3 and 7 cm distance between nickel sulfate and potassium dichromate patches. 589 patients with a history of nickel allergy (523 female, 66 male) were tested, with a mean age of 35 years. A log-linear modelling approach was used for statistical assessment of the relation between the distance separating neighbouring patch tests with nickel and dichromate and the reactions to the allergens. Non-reproducibility coefficients were compared by the generalized version of Fisher's exact test for arbitrary 2-dimensional contingency tables. For the left side of the back, virtually no differences (p=0.70) were found in the reaction patterns obtained for the 3 distances separating nickel and dichromate patch tests. On the right side of the back, the number of reactions to dichromate patches with only 1 cm distance from moderate/strong nickel reactions was lower than the number of positive dichromate tests at larger distances from nickel tests (on the border of statistical significance: p= 0.05). Corresponding side-related results were obtained for subgroups of patients with and without a history of atopic dermatitis. The non-reproducibility of reactions to dichromate was not significantly related to the distance between neighbouring tests. Our data argue against a "spillover" effect of strong/moderate nickel reactions, but indicate that such reactions may, under certain conditions, attenuate adjacent reactions to an unrelated allergen. In the case of future verification, this will have implications for the interpretation of patch tests.

Ultraviolet potassium dichromate aerating process to determine chemical oxygen demand and biochemical oxygen demand fast

Abstract: In the environment monitoring method, active mud is first used to aerate and degrade organic pollutent in water fast, and ultraviolet potassium dichromate photometric process is then used to determine COD difference before and after degradation defined as BODs, which is converted into BODs. Meanwhile, the CODcr value of water is also determined. The method can be used in determine CODcr and BODs of industrial waste water including high chlorinated waste water produced in printing and dyeing, petrochemical, pharmaceutical, tanning, smelting, papermaking and other industry, city sewage and polluted sea water.

Organic corrosion inhibitors for zinc pigment

Abstract: A severe problem with waterborne paints containing zinc pigments is hydrogen corrosion of the zinc in the aqueous alkaline paint media. The subject of the present study is the examination of corrosion inhibition of the zinc pigment in aqueous alkaline media by different high and low molecular weight organic inhibitors compared with that given by potassium dichromate. Potassium dichromate inhibits this corrosion reaction moderately, but a 4·0 mmol addition in 100 mL of the corrodent (1·2 wt-%) is required. Heterocyclic compounds are very poor corrosion inhibitors and less effective than potassium dichromate. Certain polymers with low acid numbers and low molecular weights and one particular epoxy ester resin are more effective inhibitors than potassium dichromate. Thus, some non-toxic polymers or paint resins can be considered as possible substitutes for toxic potassium dichromate.

Synthetic liquid fuel

Abstract: A synthetic liquid fuel is prepared from methanol, ferrocene CHF,potassium dichromate, xylene and petroleum ether, and features rich raw materials, low cost, simple synthetic process and convenient application

Oxidative coloring of human hair uses freshly prepared mixture of oxidation dye composition containing metal salt and/or hydroquinone, more alkaline oxidation dye composition and acidic hydrogen peroxide

Abstract: In oxidative coloring of human hair, composition A, with pH \} 9, contains oxidation dye precursor(s) (I) and metal salt(s) and/or hydroquinone is mixed, immediately before application, with a composition B, containing (I) and alkali to increase the pH \> 9 and with an acidic hydrogen peroxide composition, giving a mixture with pH 8-10.5; applied to the hair; and washed off after 5-50 minutes. In oxidative coloring of human hair, composition A contains oxidation dye precursor(s) (I) and 0.0005-1 wt.% compound(s) selected from alkali iodides, manganese dioxide, lithium chloride, potassium dichromate, magnesium acetate, calcium chloride, barium nitrate, copper (II) chloride, copper(II) sulfate, iron chloride, cerium sulfate, vanadium sulfate and/or hydroquinone. Immediately before application, composition A, with pH \} 9, is mixed with a composition B, containing (I) and enough alkali to increase the pH to over 9 and (then) with an acidic hydrogen peroxide composition, so that the mixture has pH 8-10.5. It is applied to the hair and washed off after about 5-50 minutes.

Catalytic Kinetic Spectrophotometric Determination of Trace Iron

Abstract: A new catalytic method for determining trace iron was described.Fe(Ⅲ) could catalyze the discolouring oxidizing reaction of toluidine blue by hydrogen peroxide and potassium dichromate in sulfuric acid medium.The detection limit is 9.66×10 -9 g·mL -1 .The linear range of determination is 0～0.6μg/25mL Fe(Ⅲ).Satisfactory results were obtained for the determination of trace Fe(Ⅲ) in mineral water,radish seed,chrysanthemum ,rice and peanuts.

Sensitivity comparison of the ISO Daphnia and algal test procedures with Toxkit microbiotests

Abstract: A short comparative study has been made on the sensitivity of 2 conventional bioassays (the ISO Daphnia magna immobilization test and the ISO algal growth inhibition test with Scenedesmus quadricauda) and 3 Toxkit microbiotests: the Daphtoxkit F™ magna, also with D. magna, the Thamnotoxkit F™ with the crustacean Thamnocephalus platyurus, and the Algaltoxkit F™ assay with Selenastrum capricornutum. (presently renamed Raphidocelis subcapitata). The tests were performed on the reference chemical potassium dichromate and a real world sample: a leachate of fly ash. The results showed good correlation between the 2 algal test procedures for potassium dichromate, but not for the fly ash leachate, which may be due to the use of 2 different algal species in the test procedures… The tests with both D. magna tests on fly ash leachate gave quite comparable results, but diverging results were found for potassium dichromate. The latter differences can be explained by the (unintentional) lower water hardness which was discovered in the Toxkit assay. The anostracan crustacean T. platyurus appeared to be more sensitive than the cladoceran D. magna for potassium dichromate, but not for the fly ash leachate.

Method of treating fur skins

Abstract: FIELD: fur industry. SUBSTANCE: invention is intended for use when treating sheepskin-fur coat and peltry- ware-fur stock. Fur skins are subjected to pretannage treatment with solution containing sodium chloride, organic acid, surfactant, and sodium thiosulfate followed by tannage with chrome tanner in amounts 0.67 to 0.85% (on conversion to chromium(III) oxide) of the weight of skins. Tanner is prepared by dissolving chromite-chromates in sulfuric acid at Cr(III)-to-Cr(VI) molar ratio (0.8-1.2):1 until deoxolation and deoiling of chromium(VI) oxide are complete, after which chromium(VI) reduced and basicity of tanner is adjusted with sodium or potassium dichromate. According to invention, pretannage and tannage are carried out in presence of dimethylsulfoxide. EFFECT: improved quality of intermediate product owing to reduced surface shrinkage and increased hair-to-derma attachment. 3 cl, 1 tbl