Showing papers on "Sodium dichromate published in 1986"

Chromium (VI)-induced DNA damage in chick embryo liver and blood cells in vivo.

Abstract: Uptake of chromium (VI) and subsequent induction of DNA damage was examined in liver and blood cells of 14-day chick embryos after injection of sodium dichromate onto the inner shell membrane. Maximal loss of chromium from the inner shell membrane and distribution of chromium in liver, lung and blood was observed 2 h after injection. DNA strand breaks, interstrand cross-links and DNA--protein cross-links were measured using the alkaline elution technique. In chick embryo liver, chromium (VI) induced DNA cross-links in the absence of strand breaks. Maximal DNA cross-linking was detected in the liver 8 h after injection. Little or no DNA damage remained in the liver 10-24 h after injection. In contrast, chromium (VI) induced DNA strand breaks in the absence of cross-links in chick embryo blood cells. Maximal DNA strand breakage was observed in blood cells 8 h after injection. High levels of DNA strand breaks were present in blood cells even 24 h after treatment. These intra-embryonic tissue differences in chromium (VI)-induced DNA damage may be a result of the differences in glutathione, cytochrome P-450, other pathways of chromium (VI) metabolism or chromatin organization which exist in liver and blood cells.

Carcinogenicity study with sodium dichromate in rats.

Abstract: Summary Solutions of sodium dichromate were administered to Sprague Dawley rats by intra-tracheal instillations over a period of 30 months. Dosage was 0.01, 0.05 or 0.25 mg/kg, five times a week, or 0.05, 0.25 or 1.25 mg/kg once a week. Each group consisted of 40 male and 40 female rats. Groups left untreated or given saline served as negative controls. The highest chromate dose proved to be within the range of the maximum tolerable amount. The main determinant of effect was the concentration of chromate instilled, not the total dose per week. Non-neoplastic pulmonary lesions, which occurred predominantly in the highest dose group, were fibrotic regions containing residual distorted bronchiolar lumens or cellular inflammatory foci containing alveolar macrophages, proliferated epithelium and chronic inflammatory thickening of alveolar septa. Fourteen rats given 1.25 mg/kg sodium dichromate had a total of 20 lung tumours (12 benign, 8 malignant). One rat given 0.25 mg/kg once a week had a malignant tumour. Tumours were generally small and were non-fatal. A comparable solution of calcium chromate, which was tested at the two highest dose levels, had virtually the same effect. The positive controls, benzo(a)pyrene and dimethylcarbamyl chloride, induced a high rate of fatal malignant tumours in the respiratory tract.

Selective Oxidation of 2-Bromo-m-xylene to 2-Bromo-3-methylbenzoic Acid or 2-Bromoisophthalic Acid

Abstract: Aqueous sodium dichromate oxidation of 2-bromo-m-xylene (1) under a carbon dioxide pressure gave 2-bromoisophthalic acid (58%), while NBS-bromination of 1 followed by Sommelet oxidation to aldehyde and then potassium permanganate oxidation enabled the isolation of 2-bromo-3-methylbenzoic acid in 42% yield.

Removal of chromium from cell liquor

Abstract: Soluble hexavalent chromium values are removed from aqueous chlorate solutions by employing a critical effective ratio of OH - :Cr 2 O 7 = ions of at least 3:1 in the aqueous chlorate solution and by employing a dithionite to reduce the hexavalent chromium to trivalent chromium, preferably in the mole ratio of S 2 O 4 = :Cr 2 O 7 = of at least 3:1. The trivalent chromium forms chromic hydroxide (Cr(OH) 3 ) with the hydroxyl ions and precipitates from the aqueous chlorate solution. The process is rapid and effective in quantitative removal of hexavalent chromium from the aqueous chlorate solutions and is especially useful for the removal of sodium dichromate from cell liquor which is intended to be employed in chlorine dioxide production and which is produced by diaphragmless electrolysis of sodium chloride.

Electrospark machining solution

Abstract: A nonflammable electrospark machining solution which provides a high machining rate composed primarily of a saccharide such as cane sugar, fruit sugar or malt sugar with the density of saccharide being 5 to 55% by weight. A preservative may be added such as benzoic acid, salicylic acid, dehydroacetic acid or ethyl para-hydroxybenzoate with the latter being preferred in an amount of 0.01 to 0.1% by weight of the machining solution. Also, an anticorrosive such as sodium nitride, sodium polyphosphate, sodium dichromate, sodium silicate and triethanol amine is preferably added in an amount of 0.05 to 0.1% by weight of the machining solution.