Exposure to asbestos is associated with chronic fibrosing processes, formation of ferruginous bodies, and an increased risk of carcinoma. It is possible to relate the various biological responses to asbestos exposure in terms of fundamental effects on the redox state of cells or tissues. Collagen synthesis is mediated by the level of α-ketoglutaric acid, and the rate of collagen formation is directly related to the rates of fibrosis, including elastin formation. The increase in oxidative reactions associated with collagen formation is thought to increase the amount of ferric iron bound to cellular protein, resulting in formation of a silicate-iron(III) bond on an asbestos fiber. The iron-containing protein bound to the asbestos fiber by the strong silicate ionic bond is a ferruginous body. The corresponding decrease in the ferrous-ferric redox couple inhibits electron transport, thus stabilizing exoper-oxides and free radicals thought to be involved in the initiation of carcinomas.