Hematotoxicity and Oxidative Stress Caused by Benzene

Chronic benzene exposure results in progressive depression of bone marrow function, leading to a reduction in the number of circulating red and white blood cells. Epidemiological studies show that high-level occupational exposure to benzene results in an increased risk of aplastic anemia, acute myeloid leukemia, and chronic lymphocytic leukemia. Toxicity of benzene to be induced, it first must be metabolized to several metabolites which can accumulate in the bone marrow where they are further bioactivated by myeloperoxidases and other heme-protein peroxidases to reactive semiquinones and quinones, which lead to the formation of reactive oxygen species (ROS). ROS include superoxide radical anion, hydroperoxyl radical, hydrogen peroxide (H2O2), and the highly reactive hydroxyl radical. These species are generated by many physiological processes and can affect signal transduction cascades by altering the activities of certain protein kinases and transcription factors.