An hypothesis is presented which attempts to relate the pathogenesis of both manganese neurotoxicity and Parkinson's disease to cytotoxicity from products of catecholamine oxidation. These include the products resulting from the partial reduction of oxygen (superoxide anion, hydroxyl radical, and hydrogen peroxide) and the semiquinones and ortho quinones produced during autoxidation or oxidation of catecholamines initiated by trivalent manganese.
