Benzene must undergo a bioactivation process to have a toxic activity. The metabolites responsible for the toxic and carcinogenic action are free radicals.
Free radicals (especially oxygen free radicals) are energetically unstable and highly reactive molecules. Benzene undergoes the oxidation reaction by the hepatic microsomal system, and then by the cytochrome P450, with the introduction of two hydroxyl groups - OH. Hydroquinone originated from the oxidation of benzene becomes a very important substrate of an enzyme present in the bone marrow. The enzyme is a myeloperoxidase which catalyzes the transformation of this hydroquinone into a radical.
The free radical that is formed derives from a rupture of the oxygen-hydrogen bond of the hydroxyl group. Oxygen has an unpaired electron released by hydrogen during the breakage of the bond, thus giving the oxygen strong reactive characteristics. The activity that this radical has is very dangerous because it blocks the production of cells in the bone marrow.
