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PubMed1981

Lung-retained contaminants, urinary chromium and nickel among stainless steel welders.

The magnetic method of measuring the amount of lung retained contaminants as well as urinary chromium and nickel determinations have been performed among 83 stainless steel (SS) welders who have used manual metal arc (MMA) and tungsten inert gas (TIG) welding techniques. The welders were divided into four groups according to the time percentage used for MMA welding. Only exposure to MMA/SS welding fumes resulted in clearly elevated chromium concentrations in the urine, the correlation coefficient between the values of urinary chromium and MMA/SS percentage being very significant (p less than 0.001). Among the smokers the urinary chromium values were increased (p less than 0.05) perhaps owing to contaminated cigarettes. In many workplaces the urinary chromium values of several welders exceeded the value of 30 microgram/l which is the recommended reference value in Finland. Owing to the solubility properties of nickel compounds in SS welding fumes urinary nickel concentrations were only slightly elevated among MMA/SS welders, and therefore, the urinary nickel determinations do not reflect the level of exposure to nickel compounds. The measured average remanent magnetic field of the chest area correlated well (p less than 0.01) with the use of the MMA technique. A very significant correlation (p less than 0.001) existed between the average remanent magnetic fields of the chest and the urinary chromium values of MMA/ss welders.

Adult↗
PubMed1988

Reduction of hexavalent chromium by ascorbic acid in rat lung lavage fluid.

The reduction of hexavalent chromium [chromium(VI)] in lung lavage fluids, microsomal (S-9) fractions of lung and liver tissues, erythrocyte lysates and plasma prepared from adult rats was examined at pH 7.4 (37 degrees C). Specific reducing capacity, which was defined as the amount of chromium(VI) reduced per mg of protein in the test sample, was highest in the lavage fluids. The concomitant trivalent species [chromium(III)] was detected as complexes with some of the lavage components and probably as colloidal hydroxides. By gel filtration analysis and UV spectrometry, ascorbic acid (AsA) was identified as an important reducing factor in the lavage fluids. AsA levels in the lavage fluids were about 38 micrograms/g tissue, corresponding to 12% of total AsA in the intact lungs. The molar ratios of oxidized AsA and reduced chromium(VI) in the lavage samples were about 3:2.3 on an average. On the basis of this molar ratio, the AsA levels in the lavage fluids are equivalent to a reducing capacity of 8.4 micrograms chromium(VI)/g tissue. These results suggest that the lining layers (surfactant layers) of rat lungs provide an AsA-related capacity for protection of the cells against the toxic effects of chromates and probably other oxidants.

Animals↗
PubMed1991

Chromium, lead and cadmium in Danish milk products and cheese determined by Zeeman graphite furnace atomic absorption spectrometry after direct injection or pressurized ashing.

A method for the direct determination of chromium in homogeneous samples of milk and milk products is described. Minimum sample handling and prevention of contamination was given priority. After injection of the sample into the graphite furnace, the sample was ashed in a stream of oxygen at 650 degrees C and then further ashed at 1,100 degrees C with argon as the purge gas. Zeeman background correction was used in the atomisation step at 2,300 degrees C. The detection limit was 0.7 ng/g. Direct detection of chromium in milk, using only argon as purge gas, was inferior. Non-homogeneous and solid samples, e.g. yoghurt with fruit jam and cheese, were ashed under pressure with nitric acid before analysis. The same analytical principle as used for chromium was also used for the analysis of lead and cadmium in the samples. Analytical quality control was performed for both methods and the results are reported. The results for lead, cadmium and chromium in Danish milk and milk products were in the parts per billion or parts per trillion range and compare well with literature data. The intake of lead, cadmium and chromium from milk and milk products is less than 4% of the total Danish dietary intake of these elements. It is concluded that the contribution from milk and milk products to the total intake of lead and cadmium is toxicologically insignificant and that milk and milk products are only a minor source of the essential element chromium.

Animals↗
PubMed1976

The effect of chromium III on the intravenous glucose tolerance of rats given diets of different protein values.

The effect of chromium administration on glucose utilization was investigated in 32 rats fed either high or low protein diet. In rats fed a low protein diet of NDpE% 4.3 the glucose removal rate increased significantly following the administration of chromium. However, the administration of chromium has no effect on the glucose removal rate in rats fed high protein diet of NDpE% 10.1. The glucose removal rate of rats kept on a diet of high protein value free from chromium was significantly higher than those kept on a low protein diet. Chromium deficiency did not appear to be the only responsible cause for the impaired glucose tolerance in animals fed low protein diet. It could be concluded that both chromium supplementation and protein ingestion promote insulin secretion.

Animals↗
PubMedDate not supplied

Chromium in a series of Portuguese plants used in the herbal treatment of diabetes.

Chromium (Cr3+) is an essential micronutrient for humans. Its main action is thought to be the regulation of blood sugar, because chromium deficiency is associated with diabetic-like symptoms, and chromium supplementation is correlated with increased glucose tolerance and insulin sensitivity. Some Portuguese aromatic plants are utilized as tisanes by diabetic people as medicinal plants. Their active principle is not yet known, and the importance of their chromium content in the claimed therapeutic properties should not be discarded. Therefore, determination of chromium in some Portuguese medicinal plants was performed by flameless atomic absorption. All the analyzed plants contain chromium at the normal level for this element, but the plants used to prepare tisanes to help diabetic conditions contain higher levels (2.2 microg/g dry wt+/-0.88; n=11) than the others (0.88 microg/g dry wt+/-0.18; n=17).

Brazil↗
PubMedDate not supplied

The in vitro transformation of a rat liver epithelial cell line with chromium.

The transformation of a rat liver epithelial cell line under a wide range of doses of chromium was determined by anchorage-independent growth and tumor formation in syngeneic animals. Chronic exposure to low concentrations and brief exposure to high concentrations of hexavalent chromium (K2CrO4) transformed the cells, but one dose (1 mM K2CrO4, 2 h) was clearly optimal in this regard. The cytotoxicity, effects on cell cycle, rates of chromium uptake, and mutagenic activity under the different treatment conditions were evaluated. The results showed that cells could adapt to the presence of chromium under certain treatment conditions, but this was not the case for the optimal transforming dose. Cells treated with chromium above the optimal transforming dose showed evidence of a transient G2 arrest, whereas all lower levels of treatment did not. A low level continuous exposure to chromate was mutagenic, whereas high level short exposures, including the optimal transforming dose, were not. An increase in the amount of protein complexed with isolated nucleic acids was detected in cells following treatment with the optimal transforming dose of chromate. The results indicate that the effects of chromium on this in vitro system vary with dose, and the identification of those events relevant to metal carcinogenesis will require consideration of treatment conditions.

Animals↗
PubMed2005

[Metallurgical differentiation of cobalt-chromium alloys for implants].

BACKGROUND: Cobalt Chromium alloys are used in cemented total hip or knee arthroplasty as well as in metal-on-metal bearings in total hip arthroplasty. An increasing number of publications report about (allergic) reactions to wear particles of Cobalt Chromium alloys. Reactions to nickel are more frequent in comparison to Cobalt or Chromium particles. It is well known that different kinds of Cobalt Chromium alloys contain different amounts of alloying elements; nevertheless. The aim of the current work was to compare the different Cobalt Chromium alloys according to ASTM F or ISO standards in respect to the different alloying elements. MATERIAL AND METHODS: Co28Cr6Mo casting alloys according to ASTM F 75 or ISO 5832-4 as well as forging alloy types according to ASTM F 799 and ISO 5832 such as Co20Cr15W10Ni, Co35Ni20Cr, Fe40Co20Cr10Ni, Co20Cr20Ni, and Co28Cr6Mo were analyzed in respect to their element content of Co, Cr, Ni, Mo, Fe, W, and Mn. RESULTS: In 1935 the Cobalt based alloy "Vitallium" Co30Cr5Mo basically used in the aircraft industry was introduced into medicine. The chemical composition of this alloy based on Cobalt showed 30 wt.% Chromium and 5 wt.% Molybdenum. The differentiation using alloy names showed no Nickel information in single alloy names. CONCLUSION: The information given about different alloys can lead to an unprecise evaluation of histopathological findings in respect to alloys or alloying constituents. Therefore, implant manufacturers should give the exact information about the alloys used and adhere to European law, Euronorm 93/42/EWG.

Chromium Alloys↗
PubMed2001

Chromium treatment decreases the sensitivity of 5-HT2A receptors.

RATIONALE: Recent case series suggest that chromium picolinate in doses of 400 microg daily may have antidepressant properties, perhaps through increasing the peripheral availability of tryptophan for brain serotonin (5-HT) synthesis. OBJECTIVES: To determine the effects of chromium treatment on plasma tryptophan availability and on brain 5-HT function in human and animal models. METHODS: We studied the effects of short-term chromium supplementation on plasma concentrations of tryptophan and other large neutral amino acids. Brain 5-HT function was assessed by measuring the corticosterone/cortisol response to the 5-HT precursor, 5-hydroxytryptophan (5-HTP), a response believed to be mediated via indirect activation of 5-HT(2A) receptors. RESULTS: In rats, chromium increased peripheral and central tryptophan availability and elevated brain 5-HT content. Changes in peripheral tryptophan availability were not seen in humans but in both rats and humans, chromium lowered the cortisol response to challenge with 5-HTP. CONCLUSIONS: Chromium can modify brain 5-HT function in humans and animals, perhaps by altering the sensitivity of central 5-HT(2A) receptors.

Adult↗
PubMed2001

Determination of chromium in river waters by electrothermal atomic absorption spectrometry with preconcentration on a tantalum wire.

The preconcentration of chromium on tantalum wire followed by electrothermal atomic absorption spectrometry with a tungsten tube atomizer is described. The preconcentration is accomplished by adsorbing chromium on a tantalum wire. The optimal immersion time was 3 mm. The best pH for chromium adsorption was 3. Under optimal conditions, the detection limit was 15 pg mU1 (3 x SIN). The effects on the preconcentration of chromium by large amounts of contaminants were evaluated. Even though matrix elements existed in 10(3)-10(4)-fold excess in water, the chromium absorption signal was not affected by the matrix elements. The method with preconcentration on tantalum wire was applied to the determination of chromium in river water.

Adsorption↗
PubMed1985

Semi-automated determination of chromium in whole blood and serum by Zeeman electrothermal atomic absorption spectrophotometry.

Direct determination of normal and elevated levels of chromium in whole blood and serum can be achieved using Zeeman effect electrothermal atomic absorption spectrophotometry. Whole blood and serum levels of chromium were determined for an apparently healthy population and whole blood chromium levels for renal dialysis patients. Blood and serum specimens were diluted with distilled deionized water and Triton X-100. The analyses were performed utilizing air as the alternate gas to facilitate ashing in one of the char steps. Within-run precision studies for whole blood chromium determinations gave relative SD values of 4.75 and 4.65% for 0.358 and 0.172 microgram/l, respectively. Within-run precision studies for the serum chromium analysis yield relative SD values of 5.26 and 2.67% for 0.156 and 0.300 microgram/l, respectively. Detection limits were 0.025 and 0.018 microgram/l for whole blood and serum, respectively. The mean chromium level found in whole blood and serum specimens from apparently normal individuals were 0.371 microgram/l (n = 37) and 0.130 microgram/l (n = 19), with ranges of 0.120-0.673 and 0.058-0.388 microgram/l, respectively.

Autoanalysis↗
PubMed1993

A pharmacokinetic model for chromium.

Reduction of hexavalent chromium (Cr(VI) to trivalent chromium (Cr(III) and differential kinetics of Cr(III) and Cr(VI) are important determinants of the disposition and toxicity of chromium. A physiologically based model of chromium disposition in the rat has been developed. The model takes into account different absorption and reduction rates in the lung and gastrointestinal tract; different efficiencies of transfer of Cr(III) and Cr(VI) into tissues including erythrocytes, where Cr(VI) is reduced to Cr(III) and retained for an extended period of time; uptake and storage in bone; and reabsorption of chromium from the gastrointestinal tract. The model is shown to be capable of generating the observed distributions of chromium between plasma and erythrocytes in rats given Cr(VI) intragastrically, intraduodenally, or intratracheally.

Animals↗
PubMed2005

Short-term batch studies on biological removal of chromium from synthetic wastewater using activated sludge biomass.

Biological treatment of Cr(VI)-containing wastewater has drawn much attention recently as a method to treat environmental Cr(VI) contamination. The activated sludge method, due to its convenient operation and easy-to-scale-up, has been widely applied to treat municipal wastewater and some industrial wastewaters. In order to develop a suitable technique using activated sludge as the biomass to continuously remove Cr(VI) from wastewater, this paper investigated in short-term batch experiments the environmental elements affecting chromium biological removal from synthetic wastewater. The dissolved oxygen (DO), Cr(VI) initial concentration, biomass density, temperature, glucose content in the influent and contact time were observed to strongly influence chromium removal. It was found that the chromium removal efficiency decreased with the increase of DO and Cr(VI) initial concentration as well as glucose content in the feed, but increases in temperature and contact time improved the chromium removal efficiency. Although raising biomass concentration resulted in an increased chromium removal efficiency under both anaerobic and aerobic conditions, its influence on specific chromium removal was not significant.

Bioreactors↗
PubMed2005

Removal of chromium from industrial waste by using eucalyptus bark.

Several low cost biomaterials such as baggase, charred rice husk, activated charcoal and eucalyptus bark (EB) were tested for removal of chromium. All the experiments were carried out in batch process with laboratory prepared samples and wastewater obtained from metal finishing section of auto ancillary unit. The adsorbent, which had highest chromium(VI) removal was EB. Influences of chromium concentration, pH, contact time on removal of chromium from effluent was investigated. The adsorption data were fitted well by Freundlich isotherm. The kinetic data were analyzed by using a first order Lagergren kinetic. The Gibbs free energy was obtained for each system and was found to be -1.879 kJ mol(-1) for Cr(VI) and -3.885 kJ mol(-1) for Cr(III) for removal from industrial effluent. The negative value of deltaG0 indicates the feasibility and spontaneous nature of adsorption. The maximum removal of Cr(VI) was observed at pH 2. Adsorption capacity was found to be 45 mg/g of adsorbent, at Cr(VI) concentration in the effluent being 250 mg/l. A waste water sample containing Cr(VI), Cr(III), Mg, and Ca obtained from industrial unit showed satisfactory removal of chromium. The results indicate that eucalyptus bark can be used for the removal of chromium.

Adsorption↗
PubMed2005

Lime enhanced chromium removal in advanced integrated wastewater pond system.

The removal of trivalent chromium from a combined tannery effluent in horizontal settling tanks and subsequent Advanced Integrated Wastewater Pond System (AIWPS) reactors was investigated. The raw combined effluent from Modjo tannery had pH in the range of 11.2-12. At this pH, a trivalent chromium removal of 46-72% was obtained in the horizontal settling tanks after a one-day detention time. Trivalent chromium precipitated as chromium hydroxide, Cr(OH)3. 58-95% Cr(III) was removed in the advanced facultative pond (AFP) where the water column pH of 7.2-8.4 was close to pH 8, which is the optimum precipitation pH for trivalent chromium. Chromium removals in the secondary facultative pond (SFP) and maturation pond (MP) were 30-50% and 6-16%, respectively. With Cr(III) concentration of 0.2-0.8 mg/l in the final treated effluent, the AIWPS preceded by horizontal settling tanks produced effluent that could easily meet most of the current Cr(III) discharge limits to receive water bodies.

Calcium Compounds↗
PubMed2005

Characterization of adsorbent composition in co-removal of hexavalent chromium with copper precipitation.

Mechanisms of hexavalent chromium co-removal with copper precipitation by dosing Na2CO3 were studied with a series of well-designed batch tests using solutions containing 150 mg l-1 Cu(II) and 60 mg l-1 Cr(VI). It was found that direct precipitation of chromium through formation of copper-chromium bearing precipitates (in the form of CuCrO4) was one of the main mechanisms contributing to chromium co-removal at pH close to 5.0, and adsorption of chromium at a higher pH by freshly formed copper-carbonate precipitates (adsorbent) contributed to further chromium co-removal. Since, according to solubility products, neither copper-carbonate nor copper-hydroxide precipitates can be produced at pH around 5.0 for a pure 150 mg l-1 copper precipitation, characterization of copper-carbonate precipitates (adsorbent) was carried out through developing pC-pH curves of the systems by both equilibrium calculations and MINEQL+ 4.5 (a chemical equilibrium modeling software), and also through laboratory determination of the precipitate composition, such as gravimetric analyses, inorganic carbon percentage and EDAX spectrum analyses. CuCO3.Cu(OH)2, or a combination of CuCO3.Cu(OH)2 (in majority) and Cu(OH)2 (in minority) were suggested to be the major constituent of the precipitates obtained from the copper solution with Na2CO3 dosing.

Adsorption↗
PubMed2007

Chromium accumulation by the hyperaccumulator plant Leersia hexandra Swartz.

Leersia hexandra Swartz (Gramineae), which occurs in Southern China, has been found to be a new chromium hyperaccumulator by means of field survey and pot-culture experiment. The field survey showed that this species had an extraordinary accumulation capacity for chromium. The maximum Cr concentration in the dry leaf matter was 2978 mg kg(-1) on the side of a pond near an electroplating factory. The average concentration of chromium in the leaves was 18.86 times as that in the pond sediment, and 297.41 times as that in the pond water. Under conditions of the nutrient solution culture, it was found that L. hexandra had a high tolerance and accumulation capacity to Cr(III) and Cr(VI). Under 60 mg l(-1) Cr(III) and 10 mg l(-1) Cr(VI) treatment, there was no significant decrease of biomass in the leaves of L. hexandra (p>0.05). The highest bioaccumulation coefficients of the leaves for Cr(III) and Cr(VI) were 486.8 and 72.1, respectively. However, L. hexandra had a higher accumulation capacity for Cr(III) than for Cr(VI). At the Cr(III) concentration of 10 mg l(-1) in the culture solution, the concentration of chromium in leaves was 4868 mg kg(-1), while at the same Cr(VI) concentration, the concentration of chromium in leaves was only 597 mg kg(-1). These results confirmed that L. hexandra is a chromium hyperaccumulator which grows rapidly with a great tolerance to Cr and broad ecological amplitude. This species could provide a new plant resource that explores the mechanism of Cr hyperaccumulation, and has potential for usage in the phytoremediation of Cr-contaminated soil and water.

Biodegradation, Environmental↗
PubMed2004

Biological treatment of tannery wastewater in the presence of chromium.

Experiments were carried out to determine the feasibility of treating tannery wastewater containing chromium, an inhibiting compound, with sequencing batch reactors (SBR). The maximum chromium concentration tolerated by microorganisms was determined through aerobic and anoxic batch experiments, and the biomass inhibition process was analyzed in a lab scale reactor at increasing chromium concentrations. The results obtained, in batch experiments and in the SBR reactor, have demonstrated that chromium addition had less influence on the denitrification bacteria than on the nitrification bacteria. In addition, it was observed that nitrification and denitrification rates, at the same chromium concentration, were higher in the SBR reactor than in batch experiments with unacclimated biomass. Experimental results confirm that sequencing batch reactors are able to produce a more resistant biomass, which acclimates quickly to inhibiting conditions. A large amount of chromium was found in the sludge from the reactor, while the effluent was devoid of the inhibiting metal.

Biodegradation, Environmental↗
PubMed2006

Role of heteroatoms in activated carbon for removal of hexavalent chromium from wastewaters.

Heteroatoms are elements including sulfur, nitrogen, oxygen and hydrogen which are found on the surface of activated carbons. This study investigated the surface modification arising from heteroatoms bonding to carbon aromatic rings within the activated carbon and their corresponding influence on the chromium adsorption process. Activated carbons were prepared from bagasse by physical. Chromium removal capacities of these activated carbons by adsorption and reduction were determined. Models which related the chromium adsorption and reduction capacities of activated carbons to carbon acidity and heteroatom site concentrations were established using multi-variable linear regression method. It was found the individual heteroatoms contributed separately to the basicity of the carbon which in turn determined the mechanism by which chromium was removed from solution. The surface areas of the carbons were also observed to influence the adsorption and reduction of chromium. These understandings provide the fundamental method of optimising chromium removal through suitable control of carbon surface chemistry and textural properties.

Carbon↗