Mechanisms of free radical chemistry and biochemistry of benzene.

omicron-Tyrosine (omicron-Tyr) was used as a specific biomarker for .OH radicals generated in biosystems. Specificity of omicron-Tyr as an .OH biomarker was based on previous studies in systems exposed to ionizing radiations. Fresh muscle tissue incubated with benzene for 1 hr at 38 degrees C exhibits formation of omicron-Tyr as seen in the cases of ethanol- and carbon tetrachloride-exposed systems. Gas chromatography/mass spectrometry selective ion monitoring measurements of omicron-Tyr yields in chicken breast muscle incubated with water or benzene indicate levels of less than 0.1 ppm and 3.0 +/- 0.5 ppm of omicron-Tyr, respectively. Formation of .OH is presumed to originate via a Haber-Weiss reaction of H2O2 with Fe(II) preceded by the formation of .O2- and H2O2 from distorted mitochondria.