Trinitrotoluene (TNT) increased the formation of adrenochrome from adrenaline and the formation of formaldehyde from methanol in rat liver mitochondria and microsomes in vitro as well as in monkey liver mitrochondria and microsomes in vivo. The effects were more prominent at higher TNT concentrations. These findings indicate that TNT enhances the production of superoxide radicals (O_2~-) and hydrogen peroxide (H_2O_2). The production of O_2~- was more prominent in systems containing added TNT than in those containing added benzyl viologen. H_2O_2 production by mitochondria was more pronounced in the liver than in other organs, but its production by microsomes was more pronounced in the brain than in other organs. The results suggest that TNT undergoes cycling reduction which produces oxidative stress. 1989 Academic Press, Inc. The effects of adrenochrome and adriamycin from the formation of formaldehyde from methanol in rat liver mitochondria and microsomes in vitro as well as in monkey liver mitrochondria and microsomes in vivo. These effects were more prominent at higher TNT concentrations. These effects were more prominent at higher TNT concentrations. indicate that TNT enhances the production of superoxide radicals (O_2 ~ -) and hydrogen peroxide (H_2O_2). The production of O_2 ~ - was more prominent in systems containing added TNT than in that containing added benzyl viologen. H_2O_2 production by mitochondria was more pronounced in the liver than in other organs, but its production by microsomes was more pronounced in the brain than in other organs. The results suggest that TNT undergoes cycling reduction which produces oxidative stress. 1989 Academic Press, Inc.