At what exposure level does benzene cause molecular change to the blood?

At what exposure level does benzene cause molecular change to the blood?

• A. 10 ppm
• B. 15 ppm
• C. 20 ppm
• D. 25 ppm

Answer: (D)

Benzene affects the blood by its metabolites harming the bone marrow, where blood cells are formed. The first molecular changes in the blood occur when exposure reaches a level where enough benzene accumulates to disrupt those hematopoietic processes. In the scenario given, that threshold is around twenty-five parts per million in air, so this is the exposure level at which initial blood changes are observed. Exposures below this level are less likely to show detectable blood changes, while higher exposures produce more pronounced hematotoxic effects over time. This underscores why controlling benzene exposure is important to protect the blood-forming system.

Benzene affects the blood by its metabolites harming the bone marrow, where blood cells are formed. The first molecular changes in the blood occur when exposure reaches a level where enough benzene accumulates to disrupt those hematopoietic processes. In the scenario given, that threshold is around twenty-five parts per million in air, so this is the exposure level at which initial blood changes are observed. Exposures below this level are less likely to show detectable blood changes, while higher exposures produce more pronounced hematotoxic effects over time. This underscores why controlling benzene exposure is important to protect the blood-forming system.