Based on examination of exposure monitoring studies, we speculate that under ambient conditions benzene binds appreciably to plasma proteins. The binding capacity, n*[β], is estimated to be on the order of 10-9x M (90.0 ng/L) and the association constant, Kas, on the order of 2 × 1010 M-1 (.3 L/ng). These values indicate that protein binding of benzene is characterized by a very small capacity with a very large affinity. We predict that steady-state exposure to ambient benzene air concentrations in the range of 10 ppb to 1 ppb will result in 35 to 80 percent of benzene in blood being bound to plasma proteins.
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