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At least 19 recordsLinked to original sources
PubMed1991

[Exposure to chromium compounds during processing of chromium iron ore].

The work verifies data gathered by Occupational Hygiene departments of Sanitary-Epidemiological Stations about workers exposure to chromium compounds in the processing of chrome iron ore. Research showed that 7 plants were involved in the processing of chrome iron ore and that the number of workers directly employed in the process amounted to 215-230. About 150 workers were exposed to high concentrations of chromium compounds which exceeded hygienic standards. All of them were employed only in metallurgical plants. The remaining 80-100 workers subjected to the study exposed to relatively low chromium concentrations were employed in chemical plants and refractory materials plants.

Air Pollutants, Occupational↗
PubMed1983

Lymphocyte stimulation by trivalent and hexavalent chromium compounds in patients with chromium sensitivity. An aid to diagnosis.

Peripheral blood lymphocytes from 31 patients with a positive patch test to potassium dichromate (K2Cr2O7) and from 24 healthy controls were stimulated with various concentrations of chromium chloride (CrCl3) and/or chromium basic sulphate (Cr4(SO4)5(OH)2), sodium chromate (Na2CrO4) or K2Cr2O7 on various days of culture. Both trivalent and hexavalent chromium compounds could induce lymphocyte transformation, as measured by increased DNA synthesis. The response occurred in the T-enriched population and was monocyte dependent. Lymphocytes from 11 of these patients could not be stimulated with the chromium compounds in vitro, whereas the in vivo serial dilution test (SDT) was positive in 4 and negative in 7 of them. Lymphocytes from 2 patients with a negative in vivo SDT showed a positive response in vitro. The strength of the in vivo SDT results did not correlate well with the height of in vitro responses. The DNA synthesis test seems to be a reliable in vitro method to aid in the diagnosis of chromium sensitivity.

Adult↗
PubMed1986

Induction of SOS genes of Escherichia coli by chromium compounds.

The induction of several SOS genes of Escherichia coli such as recA, umuC, and sfiA by hexavalent (K2Cr2O7, K2CrO4, and CrO3) and trivalent (CrCl3, Cr(NO3)3, and (CH3COO)3Cr) compounds of chromium was studied. Induction was measured as beta-galactosidase activity, using lacZ gene fusions under the control region of different SOS genes. The hexavalent chromium forms induced the genes responsible for massive synthesis of RecA protein, error-prone repair, and inhibition of cell division. On the other hand, the trivalent chromium compounds were unable to induce any of the SOS genes tested. Individual assay of hexavalent chromium compounds showed that K2Cr2O7 was a stronger inducing agent of those three SOS genes tested than K2CrO4, which, in turn, was stronger than CrO3. All this data led to the conclusion that hexavalent chromium compounds, but not trivalent, are proficient agents of induction of the SOS system and can produce indirect mutagenesis in Escherichia coli.

Cell Division↗
PubMed1996

[Molecular effects of chromium compound activity].

Chromium(VI) compounds produce a variety of DNA damage such as DNA single strand breaks, alkali-labile sites and DNA-protein cross-links in vivo and in cultured cells. Chromium(III) compounds bound to isolated DNA and proteins. Cr(VI) readily entered cell through general anion channels. In contrast, Cr(III) did not readily cross cell membranes. Inside cells Cr(VI) is reduced through intermediates to Cr(III) by cellular reductants. Reactive intermediates formed during intracellular Cr(VI) reduction might be responsible for some chromate genotoxicity. Ascorbic acid decreases chromate induced alkali-labile sites and chromium inhibition of glutathione reductase, but it enhances DNA-protein cross-links and cytotoxicity caused by this metal.

Animals↗
PubMed1983

[Effects of chromium compounds on the respiratory system. 2. Difference between water-soluble hexavalent and trivalent compounds].

Transference and transformation of chromium compounds, known as occupational carcinogens, in the lung of rats were studied by determining blood chromium levels after a single mist inhalation or an intravenous injection of water-soluble chromic acid (hexavalent) and chromium chloride (trivalent). Conclusion drawn from this study are as follows: Transference of chromium from the lung to the blood stream is ended quickly after the inhalation of chromic acid mist. Alveolar permeability of hexavalent chromic acid is much higher than that of trivalent chromium chloride. The greater part of the transferred chromium in the blood after the inhalation of chromic acid mist is not transformed to any other form; therefore, it seems to be present as the hexavalent form. The hexavalent chromic acid in the blood diffused to the liver, kidneys and the spleen, but the trivalent chromium chloride distributed only in the blood. The hexavalent chromic acid in the blood decreased more slowly than the trivalent chromium chloride. The biological half-time of the chromic acid in the blood was about 60 hours, whereas that of the chromium chloride was only about 2 hours. These results suggest that the water-soluble hexavalent chromium compounds may be apparently different from the trivalent chromium compounds in the transference from the lung and following distribution in the body. These differences might be caused by the high permeability through the cell membrane in hexavalent chromium compounds and the high possibility of binding with proteins in trivalent chromium compounds.

Aerosols↗
PubMed1997

Long-term exposure of male and female mice to trivalent and hexavalent chromium compounds: effect on fertility.

Sexually mature male and female mice at 50 days of age were exposed to trivalent (Chromium chloride) or hexavalent (potassium dichromate) chromium compounds in drinking water for 12 weeks. The effects of the direct chromium exposure on fertility was assessed at day 140 of age. Fertility was significantly reduced in males exposed to the trivalent chromium compound. The number of implantation sites and the number of viable fetuses was significantly reduced in females impregnated by males exposed to the hexavalent chromium compound. The number of resorptions and dead fetuses was increased in females impregnated by males exposed to trivalent and hexavalent chromium compounds. The exposure of female mice to trivalent and hexavalent chromium compounds significantly reduced the number of implantation sites and the number of viable fetuses. The number of females with resorptions was significantly increased in hexavalent chromium exposed females. The number of resorptions was increased in trivalent and hexavalent exposed females. Body, seminal vesicles and preputial gland weights were significantly reduced in males exposed to trivalent and hexavalent chromium, whereas testes weight was significantly increased in males exposed to these compounds. Furthermore, ovarian weight was significantly increased in females exposed to trivalent and hexavalent chromium, whereas uterine weight was significantly decreased in trivalent chromium exposed females. In conclusion, the ingestion of trivalent and hexavalent chromium compounds by adult male and female mice would cause adverse effects on fertility and reproduction.

Animals↗
PubMed1997

Effects of different chromium compounds on blood pressure and lipid peroxidation in spontaneously hypertensive rats.

In a previous study, we found that oral chromium nicotinate overcame sucrose-induced hypertension in spontaneously hypertensive rats (SHR). Accordingly, we examined more chromium compounds to determine if others were more or less effective in regulating blood pressure (BP) of SHR. Since chromium is postulated to be an antioxidant, we also assessed the ability of different chromium compounds to alter free radical formation measured by determining thiobarbituric acid reactive substances (TBARS). The control group of SHR ingested a diet low in chromium, and 5 other groups ate the same diet with various chromium compounds added at 5 ppm-chloride, acetate, nicotinic acid-glycine-cysteine-glutamic acid (NA-AA), picolinate, and nicotinate. Following this, the rats were challenged with drinking water containing 5% and 10% w/v sucrose. Except for NA-AA, all chromium compounds inhibited the sucrose-induced elevation of systolic BP; and acetate, picolinate, and nicotinate chromium compounds lowered HbAIC below control. Only chromium acetate and nicotinate significantly lowered both hepatic and renal TBARS. Chromium picolinate lowered hepatic TBARS, and chromium chloride and NA-AA lowered neither. We conclude that chromium, rather than a specific ligand, plays a major role in ameliorating sucrose-induced BP elevations and can act as an antioxidant.

Animals↗
PubMed1980

Metabolic fate of chromium compounds. I. Comparative behavior of chromium in rat administered with Na251CrO4 and 51CrCl3.

Comparative metabolic fate of labelled chromium chloride and sodium chromate and interaction of these compounds in the rat liver and blood were investigated after their oral and intravenous administration. Gastrointestinal absorption of both compounds was below 1% of the oral dose, but trivalent chromium showed higher radioactivity than the hexavalent form in rats (biological half-life: CrCl3 91.79 days, Na2CrO4 22.24 days). The higher residual activity of the trivalent chromium was also observed after intravenous administration. Both forms of chromium were excreted more in the urine via the kidney than in the intestinal tract after intravenous administration. When 51CrCl3 and Na251CrO4 were injected into rats, in the time-distribution patterns of 51Cr in the organs, a significant difference was shown between oxidation states of the two compounds, especially in subcellular fractions of the liver and blood constituents. This significant difference mainly observed in the rat blood came from the fact that trivalent chromium possessed a high binding activity for transferrin in plasma, while hexavalent chromium was permeable into red cells and bound with hemoglobin.

Animals↗
PubMed1995

Physico-chemical fate of chromium compounds in the sheep lung model.

Transmission electron microscopy (TEM) equipped with energy-dispersive x-ray analysis (EDX), electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectrometry (SIMS), and laser microprobe for mass analysis (LAMMA) were used to follow the fate of chromium compounds deposited in the sheep tracheal lobe. Four chromium compounds were used: two chromium(VI) compounds (lead chromate and chromium trioxide) and two chromium(III) compounds (chronic oxide and chromium sulfate). Chromium trioxide is very soluble and the other three are slightly soluble. The compositions, concentrations, and sizes of particles were determined in the bronchoalveolar lavages (BAL) at d 2, 3, 5, and 30 after instillation and on the lung samples collected at d 31. The concentrations of particles in the BAL samples separated the chromium compounds in two groups where Cr2O3 and PbCrO4 (as Pb) were higher than Cr2(SO4)3, PbCrO4 (as Cr), and CrO3. The half-life for alveolar clearance of Cr2O3 and Cr2(SO4)3 has been calculated respectively at 11 and 80 d. Prismatic PbCrO4 particles break up in the lung and sustain a high concentration of isometric particles of lead chromate and another lead-containing compound in the BAL. The CrO3 instilled particles react with endogenous compounds or are transformed to insoluble hydroxyl complexes instead of diffusing very rapidly through the alveolar-capillary barrier. The alveolar clearance as measured in the BAL is not different from the control.

Animals↗
PubMedDate not supplied

[Reparative DNA synthesis in the lymphocytes of persons coming in contact with chromium compounds in industry].

The intensity of repair DNA synthesis in the lymphocytes of persons who were in contact with chromium compounds was studied depending on the contact duration. It is discovered that the intensity of repair DNA synthesis is reduced with the increase of the contact duration with chromium compounds. It is suggested that the mutagenic effect of chromium compounds is connected with the influence on the repair DNA synthesis in human cells.

Cells, Cultured↗
PubMed1983

Sister chromatid exchanges in Chinese hamster V79 cells treated with the trivalent chromium compounds chromic chloride and chromic oxide.

The induction of sister chromatid exchanges (SCEs) in Chinese hamster V79 cells exposed to soluble CrCl3 and insoluble Cr2O3, compounds of trivalent chromium (Cr3+), was determined. Their ability to induce SCEs was compared with those of three hexavalent chromium (Cr6+) compounds: K2CrO4, Na2CrO4 and Na2Cr2O7. Both the delay in progression through the cell cycle induced by Cr3+ compounds and the SCE frequencies in the delayed cells were also evaluated. The exposure for 28 h to CrCl3 and Cr2O3 at concentrations of 9.7-39 micrograms and of 34-136 micrograms of Cr3+ per ml, respectively, induced a statistically significant (p less than 0.001) dose-dependent increase in SCEs up to 1.9-fold (CrCl3) and 4-fold (Cr2O3) over control levels. Compared with the effective concentrations of Cr6+ compounds, which produced up to 4-fold increase of SCEs, inducing concentrations of CrCl3 and Cr2O3 were 300- and 1000-fold higher in terms of chromium. By prolongation of treatment time up to 48 h, a progressive dose- and time-related enhancement in SCE frequencies induced by Cr3+ compounds in delayed cells was observed. Lower concentrations of Cr2O3, without effect after 28 h of treatment, induced an increase of SCEs by prolongation of exposure time.

Animals↗
PubMed1990

Role of valence state and solubility of chromium compounds on induction of cytotoxicity, mutagenesis, and anchorage independence in diploid human fibroblasts.

We previously showed that carcinogenic nickel, arsenic, and chromium(VI) compounds induced anchorage independence (AI) in diploid human fibroblastic cells (HFC) derived from foreskins (K. A. Biedermann and J. R. Landolph, Cancer Res., 47: 3815-3823, 1987). To elucidate the role of the valence state of chromium and solubility of chromium compounds in inducing AI, we studied the ability of soluble and insoluble hexavalent [chromium(VI)] and trivalent [chromium(III)] chromium compounds to induce mutation and AI in HFC. Chromium(VI) compounds (PbCrO4, CaCrO4, Na2CrO4, and CrO3) were 1000-fold more cytotoxic to HFC (average 50% lethal dose 0.5 microM) than chromium(III) compounds (CrCl3, Cr2O3, Cr2S3; average 50% lethal dose 500 microM). However, equal concentrations (0.1-10.0 microM) of soluble or insoluble chromium compounds in either +6 or +3 valence states induced similar increases in frequencies of AI in HFC (100-200/10(5]. Chromium(VI)- and chromium(III)-induced AI was a stable phenotype. All soluble chromium(VI) and insoluble chromium(III) compounds studied induced mutation to 6-thioguanine resistance at cytotoxic concentrations in HFC. Insoluble PbCr(VI)O4 and a soluble form of Cr(III)Cl3 were inactive in this assay. Mutation induction by chromium(III) compounds only occurred at cytotoxic concentrations (100-1000 microM) 1000-fold greater than those concentrations of chromium(VI) compounds (0.25-1 microM) which were cytotoxic, mutagenic, and induced AI. Soluble hexavalent Na2(51)CrO4 was taken up facilely by cells at concentrations that induced cytotoxicity, mutation, and AI. At concentrations of 0.25-1.0 microM, which induced AI but were not cytotoxic or mutagenic, or concentrations of 1-1000 microM, which were cytotoxic and mutagenic, soluble trivalent 51CrCl3 was not taken up by cells. An insoluble form of CrCl3 was not taken up intracellularly but did avidly associate with cells over the concentration range 1 to 100 microM which induced AI, cytotoxicity, and mutagenicity. Therefore, both chromium(VI) and chromium(III) compounds induced genotoxic effects in human fibroblasts. Cellular uptake, cytotoxicity, mutagenicity, and AI induced by soluble chromium(VI) compounds all occurred at the low concentrations of 0.2 to 1.0 microM; hence mutagenicity and induction of AI may be coupled for soluble chromium(VI) compounds but not for insoluble PbCrO4, which induced AI but was not mutagenic. Cytotoxicity and mutagenicity of insoluble chromium(III) occurred at concentrations of 10-100 microM, but induction of AI occurred at concentrations of 0.1-10 microM, indicating that inductions of mutagenicity and AI were not coupled for chromium(III) compounds.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Adhesion↗
PubMed1993

Role of chemical species and exposure characteristics in cancer among persons occupationally exposed to chromium compounds.

Epidemiologic studies on chromate workers are considered with special reference to the valency of chromium compounds, carcinogenic potency, and water solubility. It is assumed that all hexavalent chromium compounds are carcinogenic to humans when inhaled but that there is no evidence that trivalent compounds are carcinogenic. It is suggested that zinc chromate is a highly potent carcinogen and also that calcium chromate may be carcinogenic. There are indications that chromates of low water solubility may be less potent carcinogens than compounds of greater solubility. Evidence is also presented for possible interactions with smoking and other factors involved in work-related cancers.

Adult↗
PubMed1993

Monitoring of total chromium in rat fluids and lymphocytes following intratracheal administration of soluble trivalent or hexavalent chromium compounds.

1. Intratracheal instillation of sodium dichromate (CrVI) and chromium acetate hydroxide (CrIII) to male Wistar rats gave rise to increased chromium concentrations in whole blood, plasma and urine up to 72 h post exposure; peak concentrations were reached at 6 h after exposure. 2. The ratio of whole blood chromium to plasma chromium concentrations was significantly different for Cr(VI) and Cr(III) treatments. Both blood chromium and plasma chromium assays should therefore be used for the assessment of chromium exposure. 3. Chromium was also detected in peripheral lymphocytes. Cr(VI), but not Cr(III) accumulated significantly in the lymphocytes after treatment. These cells have potential to be used for biomarkers of the assessment of exposure to chromium compounds.

Acetates↗
PubMed1979

Chromosomal aberrations and sister-chromatid exchanges in Chinese hamster cells treated in vitro with hexavalent chromium compounds.

Chinese hamster cells (CHO line) were treated in vitro for 30--39 h with hexavalent chromium compounds (K2Cr2O7 and Na2CrO7), at concentrations ranging from 0.1 to 1.0 microgram of Cr6+ per ml, in medium containing BUdr. Chromosomal aberrations and sister-chromatid exchanges were scored on BUdr-labelled 2nd division metaphases, collected at the end of treatment and stained with Giemsa. Treatment with mitomycin C 0.009--0.030 microgram/ml) was carried out as a control for the responsiveness of the cell system to chromosomal damage. Both chromium compounds induced marked mitotic delays. Chromosomal aberrations were increased about 10-fold by exposure to Cr6+ (1.0 microgram/ml). The principal aberrations observed were single chromatid gaps, breaks and interchanges, whose frequencies increased proportionally to the concentration of chromium. Dicentric chromosomes, isochromatid breaks, chromosome and chromatid rings were also induced. The frequenyc of sister-chromatid exchanges was hardly doubled 30 h after exposure to Cr6+ at 0.3 microgram/ml, whereas it was trebled 39 h after treatment, in the cells whose division cycle had been slowed down by chromium.

Animals↗
PubMed1984

Biological monitoring of occupational exposure to different chromium compounds at various valency states.

Chromium concentrations in the air were measured in seven different workroom environments, where exposure to water soluble hexavalent or trivalent compounds was expected. Urinary excretion of chromium was measured before and after the same arbitrarily chosen working day. End-of-shift urinary chromium and its increase above pre-exposure levels were closely related to the concentration of water soluble chromium (VI) in the air. The values corresponding to 50 micrograms m-3 in the air, which is the current threshold limit value in most countries, were 29.8 and 12.2 micrograms g-1 of creatinine, respectively. Urinary chromium in workers exposed to water insoluble chromates or to water soluble chromic (III) sulphate was definitely higher than that observed in subjects not occupationally exposed to chromium compounds, but it cannot be recommended as short-term exposure test for evaluation of the job-related hazard.

Absorption↗