inhalation route:
Existing evidence indicates that benzene is rapidly absorbed by humans following inhalation exposure.
Results from volunteers including males and females exposed to benzene concentrations of 170-200 mg/m3 (52-62 ppm) for 4 hours showed that retention decreased with the duration of exposure and reached a constant level after 2 hours. The amount of benzene absorbed from the lungs following inhalation of the vapors (respiratory uptake) was determined to be approximately 47% of the inhaled dose and the amount of absorbed benzene that is not excreted via the lungs (respiratory retention) was estimated to be approximately 30% of the inhaled dose. Women may retain a greater percentage of inhaled benzene than men.