A petrochemical worker develops anaemia, leucopenia and thrombocytopenia after chronic benzene exposure. The TARGET cell type and mechanism of haematotoxicity is:

• A Mature erythrocytes are directly lysed by benzene epoxide
• B Benzene metabolites (benzene-1,4-diol and 1,4-benzoquinone) accumulate in bone marrow, causing pluripotent haematopoietic stem cell damage leading to aplastic anaemia ✓
• C Benzene inhibits dihydrofolate reductase causing megaloblastic changes
• D Reactive oxygen species from benzene oxidation cause selective erythroid progenitor apoptosis

Explanation

Chronic benzene exposure causes aplastic anaemia and myelodysplastic syndrome through its reactive metabolites — principally benzene-1,4-diol (hydroquinone) and 1,4-benzoquinone — which are formed by CYP2E1 in the liver and myeloperoxidase in the bone marrow. These metabolites covalently bind to DNA and topoisomerase II in pluripotent haematopoietic stem cells, causing pancytopenia and increasing risk of acute myeloid leukaemia. Benzene does not directly lyse mature RBCs and is not a folate antagonist.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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