[The role of oxygen free radicals in asbestos cytotoxicity]

Despite numerous experiments, the cytotoxicity of asbestos is still far from being well understood. There is an increasing evidence which supports the contribution of free oxy-radicals resulting from the phagocytosis of asbestos fibres concerning macrophages neutrophils, pulmonary epithelial and endothelial cells. Both in vitro and in vivo studies revealed an asbestos-induced generation of hydrogen peroxide, hydroxyl radical and superoxide anion. The intensity of the process varies with the physico-chemical properties of the asbestos fibres. Oxygen free radical activity accounts for the lipid peroxidation of cell membranes as well as for the damage of structural proteins and DNA. However, the cells contain antioxidant enzymes such as catalase, superoxide dismutase, etc., which prevent the toxic effect of oxidants. Their activity increases when the cells are exposed to asbestos.