Generation of oxygen radicals by minerals and its correlation to cytotoxicity.
Environ Health Perspect 1994 Dec; 102(Suppl 10):111-115
A study was conducted to evaluate the potential role of several occupational mineral dusts in the generation of hydroxyl radicals and to correlate in-vitro cytotoxicity and lipid peroxidation potential with oxygen radical generation. Electronic spin resonance was used to monitor the generation of hydroxyl radicals in suspensions of mineral fibers with hydrogen-peroxide. Cytotoxicity of the minerals was determined by hemolysis of red blood cells and the release of lactate-dehydrogenase in alveolar macrophages isolated from Sprague-Dawley-rats. Spectrophotometric methods were used to measure surface iron content in mineral samples. Lipid peroxidation was assessed by incubation of mineral fibers with linoleic-acid for 1 hour. The concentration of surface iron in minerals was shown to be directly related to the potential for hydroxyl radical generation, although hydroxyl radical generation by higher iron containing minerals did not appear directly related to the cytotoxicity of minerals or to their potential to induce lipid peroxidation. A better correlation was observed with lipid peroxidation and the known pathogenicity of dusts. The author concludes that neither in-vitro toxicity studies nor the ability of the minerals to generate the more potent oxidizing agents such as hydroxyl radicals from hydrogen-peroxide can directly predict the potential for toxicity and resultant pulmonary fibrosis. An apparently better correlation exists between the ability of the minerals to induce lipid peroxidation and known toxicity and fibrogenicity in humans.
NIOSH-Author; Lung-irritants; Mineral-dusts; Cellular-reactions; Cytotoxic-effects; Respiratory-system-disorders; Free-radical-generation; Enzymatic-effects;
Author Keywords: oxygen radicals; cytotoxicity; pneumoconiosis; hemolysis; enzymes; surface iron; lipid peroxidation
Environmental Health Perspectives