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PubMed1994

Chromium(VI) reduction by ascorbate: role of reactive intermediates in DNA damage in vitro.

Reaction of chromium(VI) with one equivalent of ascorbate was studied by electron paramagnetic resonance spectroscopy in the presence of 0.10 M 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) at room temperature in 0.10 M (N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid]) (HEPES) and 0.05 M tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffers (pH 7.0 room temperature). Chromium(V), ascorbyl radical, and carbon-based DMPO-radical adducts were observed. A higher level of Cr(V) was observed in HEPES buffer and a higher level of the DMPO-radical adducts was observed in Tris-HCl buffer. Chromium-DNA binding studies were carried out in vitro for calf thymus DNA incubated with Cr(VI) and ascorbate in both buffers at 37 degrees C. Higher Cr-DNA binding was observed in HEPES buffer. DNA strand-break studies were carried out in vitro on pBR322 DNA incubated with Cr(VI) and ascorbate in both buffers at 37 degrees C. Higher percent nicking was observed in Tris-HCl buffer. Addition of DMPO decreased nicking levels in Tris-HCl buffer. These results suggest that free radicals are more reactive than Cr(V) in producing DNA strand breaks and that Cr(V) will react with DNA to produce Cr-DNA adducts. The fact that buffer affects the nature of the reactive intermediates produced upon reduction of Cr(VI) may be related to differences in intracellular metabolism of Cr(VI) and resulting DNA damage observed in various cell culture systems and animal tissues in vivo.

Animals↗

PubMed2006

The effect of the diameter of metal-on-metal bearings on systemic exposure to cobalt and chromium.

The recent resurgence in the use of metal-on-metal bearings has led to fresh concerns over metal wear and elevated systemic levels of metal ions. In order to establish if bearing diameter influences the release of metal ions, we compared the whole blood levels of cobalt and chromium (at one year) and the urinary cobalt and chromium output (at one to three and four to six years) following either a 50 mm or 54 mm Birmingham hip resurfacing or a 28 mm Metasul total hip replacement. The whole blood concentrations and daily output of cobalt and chromium in these time periods for both bearings were in the same range and without significant difference.

Adult↗

PubMed2004

Microcanalization in the epididymis to overcome ductal obstruction caused by chronic exposure to chromium - a study in the mature bonnet monkey (Macaca radiata Geoffroy).

In order to apprehend the toxic effects of chromium, an occupational/environmental pollutant, on the epididymis, adult bonnet monkeys were exposed to chromium (VI) in their drinking water at concentrations of 100, 200 and 400 p.p.m. for a chronic period of 180 days. At the end of the experimental period, testicles and segments of epididymis from control and treated monkeys were subjected to light microscopic (resin-embedded semi-thin sections) and transmission electron microscopic analyses. Among the various changes undergone by the epididymal epithelium, the present paper describes the origin of two different kinds of microcanals, probably caused by ductal obstruction. The first type of microcanal, which appears to provide passage for spermatozoa to bypass the obstructed main duct, is comparable with the one already reported in carbendazim-treated efferent ductules of the rat. The second type of microcanal, which is novel, consisted of a lumen in the epithelium enclosed by four to five cells, which are either modified basal cells, principal cells or a hitherto unknown cell type. This novel type of microcanal is suggested to be a device to entrap the spermatozoa which reach the core of the epithelium and may be a mechanism to prevent extravasation of sperm so as to avoid an autoimmune response of spermatic granuloma formation. Thus, the present study has shown that chronic exposure to chromium (VI) through drinking water can produce pathological manifestations in the epididymal epithelium but the epididymis, being a versatile organ, is capable of overcoming such adverse situations through novel devices.

Animals↗

PubMed2005

Exposure to lead, cadmium and chromium among spray painters in automobile body repair shops.

Environmental and biological monitoring of lead, cadmium and chromium levels in spray painters is reported. All of the study subjects worked in automobile body repair shops that had no standard spraying room. They were divided into 2 groups, those who wore an aerosol-removing respirator while spraying (n=20) and those who did not wear the respirator (n=50). Air in the breathing zone of each subject was sampled and analyzed for lead, cadmium and chromium levels. The subjects' blood lead levels and urinary cadmium and chromium levels were also measured along with those of a control group. The mean environmental and biological levels of these metals between the two groups of the painters were not significantly different (p>0.05). However, the biological levels of the metals were significantly higher in the study groups than in the control group (p<0.01). On-site observations revealed that improper use of an aerosol-removing respirator, lack of an isolated spraying room and poor personal hygiene habits caused the failure to prevent heavy metal exposure among the automobile spray painters.

Adolescent↗

PubMed2005

Study on anaerobic treatment of wastewater containing hexavalent chromium.

A self-made anaerobic bio-filter bed which was inoculated with special sludge showed high efficiency in removing hexavalent chromium. When pump flow was 47 ml/min and COD(Cr) of wastewater was about 140 mg/L, it took 4 h to decrease the Cr6+ concentrations from about 60 mg/L to under 0.5 mg/L, compared with 14 h without carbon source addition. Cr6+ concentrations ranged from 64.66 mg/L to 75.53 mg/L, the system efficiency was excellent. When Cr6+ concentration reached 95.47 mg/L, the treatment time was prolonged to 7.5 h. Compared with the contrast system, the system with trace metals showed clear superiority in that the Cr6+ removal rate increased by 21.26%. Some analyses also showed that hexavalent chromium could probably be bio-reduced to trivalent chromium, and that as a result, the chrome hydroxide sediment was formed on the surface of microorganisms.

Bacteria, Anaerobic↗

PubMed1991

The three dimensional distribution of chromium and nickel alloy welding fumes.

In the present study, the fumes generated from manual metal arc (MMA) and submerged metal arc (SMA) welding of low temperature service steel, and the chromium and nickel percentages in these fumes, were measured at various horizontal distances and vertical heights from the arc in order to obtain a three dimensional distribution. The MMA welding fume concentrations were significantly higher than the SMA welding fume concentrations. The highest fume concentration on the horizontal was shown in the fumes collected directly above the arc. The fume concentration vertically was highest at 50 cm height and reduced by half at 150 cm height. The fume concentration at 250 cm height was scarcely different from that at 150 cm height. The distribution of the chromium concentration vertically was analogous to the fume concentration, and a statistically significant difference in the chromium percentages was not found at the different heights. The nickel concentrations were not statistically significant within the welding processes, but the nickel percentages in the SMA welding fumes were statistically higher than in the MMA welding fumes. The highest nickel concentration on the horizontal was found in the fumes collected directly above the arc. The highest nickel concentration vertically showed in the fume samples collected at 50 cm height, but the greater the height the larger the nickel percentage in the fumes.

Air Pollutants, Occupational↗

PubMed2004

Predicting the toxicity of chromium in sediments.

Chromium exists in sediments in two oxidation states: Cr(III), which is relatively insoluble and nontoxic, and Cr(VI), which is much more soluble and toxic. Chromium(VI) is thermodynamically unstable in anoxic sediments, and acid-volatile sulfide (AVS) is formed only in anoxic sediments; therefore sediments with measurable AVS concentrations should not contain toxic Cr(VI). If this hypothesis holds true, measuring AVS could form the basis for a theoretically based guideline for Cr in sediments. Ten-day water-only and spiked sediment toxicity tests with the amphipod Ampelisca abdita were performed with Cr(VI) and Cr(III), along with sediments collected from a site contaminated with high concentrations of Cr. In sediments where AVS exceeded analytical detection limits, Cr concentrations in interstitial water were very low (<100 microg/L) and no significant toxicity to A. abdita was observed. In sediments in which AVS was not significantly greater than zero, Cr concentrations in interstitial waters increased significantly, with greater than 90% of the Cr present as Cr(VI), and mortality of A. abdita was elevated. These results demonstrate that measurements of AVS and interstitial water chromium can be useful in predicting the absence of acute effects from Cr contamination in sediments.

Amphipoda↗

PubMed2004

Direct fluorescence quantification of chromium(VI) in wastewater with organic nanoparticles sensor.

Under ultrasonic irradiation, organic fluorescence nanoparticles have been prepared by a reprecipitation method. Compared with single organic fluorophores, these nanoparticles are brighter, more stable against photobleaching and more water-soluble. They also have high room-temperature fluorescence quantum yields (approximately 20%) and a long fluorescence lifetime (approximately 0.2 micros). Based on the fluorescence quenching of nanoparticles by chromium(VI), a method for the selective determination of chromium(VI) without the separation of chromium(III) in water was developed. Under the optimal conditions, the linear range of the calibration curve was 7.0 x 10(-6) - 1.0 x 10(-4) mol L(-1). The detection limit was 2.8 x 10(-6) mol L(-1). The method is characterized by a short reaction time, stable fluorescence signals, simplicity and high selectivity. The present assay has been applied to the selective quantification of Cr(VI) in wastewater with satisfactory results.

Calibration↗

PubMed2006

Crystalline hydrous ferric oxide: an adsorbent for chromium(VI)-contaminated industrial wastewater treatment.

Synthetic crystalline hydrous ferric oxide (CHFO) (particle size 0.14 to 0.29 mm) has been used systematically for adsorptive chromium(VI) removal from contaminated water. Batch experiments were performed as a function of pH, contact time, solute concentration, and regeneration of adsorbents. Column experiments were performed for breakthrough points in the presence and absence of other ions and treatment of industrial effluent. The optimum pH range was 2.0 to 4.0. The adsorption kinetic data could be described well by both second-order and pseudo-first-order models. The isotherm adsorption data at 30 +/- 2 degrees C obeyed the Langmuir model best. The monolayer adsorption capacity was 35.7 mg/g. Chromium(VI)-rich CHFO could be regenerated up to 89 +/- 1% with 2.0 M sodium hydroxide. Regenerated column reuse showed a decrease (10 to 12%) in breakthrough capacity. Finally, the CHFO- (dried at 300 degrees C) packed column was used for the recovery (98.5 +/- 1.0%) of chromium(VI) from contaminated industrial waste effluent of Hindustan Motor Limited (Hooghly, West Bengal, India).

Adsorption↗

PubMed1977

Chelation in metal intoxication. IV. Removal of chromium from organs of experimentally poisoned animals.

In an attempt to find more reliable therapeutic or preventive agents for industrial chromium poisoning, some structurally different metal binding agents were screened for their ability to mobilize chromium from liver, kidney, brain, and testes (in vivo) and their subcellular fractions (in vitro), together with the blood corpuscles of experimentally intoxicated animals. Ethylenedinitrilotetraacetic acid (EDTA) and diethylenetriamine pentaacetic acid (DTPA) were quite successful in vivo, while ascorbic acid and 3,4-dihydroxy-L-phenyl alanine (L-DOPA) were more effective in vitro. No relationship could be observed between the structure or the molecular weight of the various chelating agents examined and their ability to remove chromium from either the tissue or their subcellular fractions.

Animals↗

PubMed2001

Effect of chromium supplementation on production and metabolic parameters in periparturient dairy cows.

The effect of supplemental chromium as chromium-methionine (Cr-Met) on production and metabolic parameters was investigated in 48 cows from 28 d before expected calving date through 28 d of lactation. Average body weight (BW) was 730 +/- 61 kg before treatment. Treatments were supplementation of 0, 0.03, 0.06, and 0.12 mg of Cr as Cr-Met/kg of BW(0.75). Dry matter intake increased linearly and quadratically during the prepartum and postpartum periods, respectively, and body condition score loss decreased linearly during the postpartum period with increasing Cr-Met. Increasing Cr-Met supplementation caused quadratic increases in milk, fat, and lactose yields. Treatments did not affect concentrations of blood metabolites and liver triglyceride. Serum insulin concentration and molar ratio of insulin to glucose for cows receiving Cr-Met were lower than for cows not receiving Cr-Met, but they increased quadratically with increasing Cr-Met. Glucose tolerance tests (GTT) were conducted on d 10 prepartum and d 28 postpartum. Chromium-methionine supplementation attenuated insulin sensitivity prepartum and enhanced glucose tolerance postpartum, but not prepartum. Basal insulin concentrations for cows receiving Cr-Met were higher than for cows not receiving Cr-Met during the prepartum GTT. During the postpartum GTT, peak glucose concentration and clearance rate decreased and half-life (t(1/2)) and time to reach basal concentration (T) were prolonged quadratically by increasing Cr-Met. Additionally, peak insulin concentration, area under the curve, and molar ratio of insulin to glucose were higher for cows not receiving Cr-Met than for cows receiving Cr-Met and t(1/2) and T were shortened quadratically by increasing Cr-Met.

Amino Acids↗

PubMed2004

Supplementing intensively grazed late-gestation and early-lactation dairy cattle with chromium.

Two hundred thirty-two primiparous and multiparous cows were assigned to a study to determine the effect of supplementing 0 or 6.25 mg/d of Cr from Cr Met on lactation and reproductive performance. Cows received treatments from 6 wk precalving through 21 wk postpartum. Precalving, treatments were incorporated into a pelleted grain mixture and group-fed. Post-calving, cows received treatments via an individual oral drench once a day after the a.m. milking. Grazed herbage was the primary diet constituent for lactating cattle. Blood was collected from a predetermined group of cows before and immediately after calving. On 4 occasions during the treatment period, milk yield was recorded and samples collected for determination of composition. Chromium supplementation had no effect on yield of milk and milk components and milk composition. Chromium supplementation decreased serum nonesterified fatty acids (NEFA) concentration (0.60 vs. 0.68 mmol/L), with chromium supplementation having the greatest impact on serum NEFA concentrations at 1 wk prepartum. Greater percentages of cows supplemented with Cr were observed to be anestrus by dairy personnel (45.5 vs. 32.0%). However, Cr supplementation tended to increase the percentage of cows pregnant in the first 28 d of the mating season (50.0 vs. 39.2%). Results indicate that Cr Met supplementation of intensely grazed, late-gestation and early-lactation dairy cattle decreased serum NEFA concentrations and tended to increase pregnancy rates in the first 28 d of the mating season.

Animal Feed↗

PubMed1985

Cancer risk of arc welders exposed to fumes containing chromium and nickel.

A retrospective follow-up study among chromium- and nickel-exposed welders, which took into consideration welding procedures, duration of exposure, and smoking habits, yielded an increased cancer risk in a comparison with an internal reference group of turners, milling cutters, and drillers, as well as in a comparison with the general population of the Federal Republic of Germany. Due to the cohort size (1 224 welders, 1 694 turners) and the fact that the observation period is still too short, confirmed statements as to the target cancer sites cannot yet be made. However, it emerges that welding with coated electrodes shows a higher cancer risk as compared to the other welding processes observed. This finding may be explained by the fact that the share of hexavalent chromium compounds in the welding fumes is greater with coated electrodes than with other processes so that a follow-up study observing the health risks of chromium and nickel fumes separately would be warranted. For the confirmation of a more favorable outcome with gas-shielded welding, a larger investigation group or a longer observation period would be required.

Adolescent↗

PubMed1979

A simple analytical technique for the determination of hexavalent chromium in welding fumes and other complex matrices.

A systematic study of analytical methods for the determination of hexavalent chromium showed that currently existing techniques are unsatisfactory when used with welding fumes, the s-diphenylcarbazide method proposed by the U.S. National Institute for Occupational Safety and Health permitting less than 1% recovery of hexavalent chromium from synthetic welding fumes of known composition. A new (carbonate leaching) technique is proposed which permits better than 80% recovery of both soluble and insoluble chromium (VI). This technique is then used as part of a general method for the determination of total chemical composition as distributed among sample fractions of different solubility. The method is specifically designed for use in the analysis of small samples and is especially suitable for the routine evaluation of health risks as found in the work environment.

Air Pollutants↗

PubMed2000

[Allergy to nickel, chromium and cobalt after osteosynthesis].

Metals are known as a common cause of contact allergies. The prevalence of sensitisation to the composite metals makes for a potential risk of osteosynthesis complications in patients suffering from long bones fractures. In the study the prevalence of delayed allergy to nickel sulphate, potassium dichromate and cobalt was estimated as well as the relation to the osteosynthesis complications. The atopy prevalence was estimated too. Persons under examination were divided into 3 groups. I--treated with osteosynthesis without complications (n = 20), II--treated with osteosynthesis with synostosis complications (n = 16) and III--negative controls (n = 34). We estimated 5% prevalence of delayed allergy to nickel in group I, 6.25% in group II and 5.8% in group III. In patients exposed to chromium we observed delayed allergy prevalence of 5.8% in group I and 3% in group III. No allergy to chromium in group II was revealed. No allergy to cobalt in all groups was revealed. The prevalence of atopy in group II was rare (6.35%) when in group I it was 45% and in controls 32%. The more frequent occurrence of type IV allergy to metals in atopic patients was not confirmed. There was no difference between the prevalence of delayed allergy to metals in groups I and II. Only one case of secondary allergy to chromium was observed.

Adolescent↗

PubMed2000

The role of chromium(V) in the mechanism of chromate-induced oxidative DNA damage and cancer.

The role that high valent chromium intermediates play in the oxidative DNA damage produced by the human carcinogen chromate Cr(VI) is of increasing interest for establishing a mechanism of genotoxicity and mutagenicity for this metal. In this review, the authors summarize experimental evidence for the formation of high valent chromium complexes (primarily the +5 oxidation state) and radical species from the reductive metabolism of Cr(VI). A case is made for a direct- or metal-mediated pathway by high valent chromium to initiate oxidative DNA damage, although the role of radical species in this oxidative process cannot be ruled out.

Animals↗

PubMed2000

The dynamics of the hexavalent chromium induced apoptotic patterns in vitro.

Although hexavalent chromium has been shown to induce apoptosis in cells cultivated in vitro, there appear to be no studies focusing on the dynamics of this process. To find out about dynamic patterns of hexavalent chromium-induced apoptosis, we treated Hep2 cells with 150 micrograms/ml potassium chromate and recorded their behavior as well as appearance of some crucial organelles using different morphological and biochemical methods. We found that Hep2 cells showed the earliest observable changes at 6 hours after the treatment (blebbing, chromatin shrinkage), with the entire apoptotic process lasting up to 24 hours. While all the observed cell features clearly prove apoptosis induced by hexavalent chromium, a typical apoptotic hallmark, DNA ladder, seems not to occur in this type of cells. On the other hand, in HL60 cells, used as a control, this ladder was observable.

Apoptosis↗

PubMedDate not supplied

Levels of calcium, aluminium and chromium in serum of exclusively breastfed infants at six months of age in Savannah region of Nigeria.

This study was undertaken to determine the levels of calcium, aluminium and chromium in the serum of apparently healthy exclusively breastfed infants at the sixth month of lactation. Forty-five infants (with a male:female ratio 2:1) were studied. They were of an average age six months and one week, weighed 6.8-10.0 kg. The mean calcium levels of 83.92 ug/ml (2.1 mmol/L) obtained is within the reference range (2.1-2.5 mmol/L) in this area. The mean level of chromium was 0.11 u/ml while that of aluminium is significantly (P < 0.001) higher than the toxic level reported by some workers, yet none of the subject was manifesting any obvious signs of toxicity. We can then infer from our data that the exclusively breastfed infants are able to extract enough calcium, aluminium and chromium from the maternal breastmilk.

Aluminum↗