An adaptation of a published, physiologically based pharmacokinetic model (PBPK) for benzene (71432), was applied to a study of concentration, duration and exposure intermittency effects, to illustrate application of PBPK modeling in valid exposure metric determination for epidemiological studies. Exposure scenarios typically encountered by petroleum distribution workers were studied. The model was based on data from human subjects, voluntarily exposed to a range of benzene concentrations and monitored through blood, urine and exhaled air for a range of measured outputs. Model outputs were fit to empirical data from humans mice and rats. Benzene and total metabolite concentrations in blood and bone marrow, were mapped over an administered concentration, time series. The model predicted total benzene metabolite concentration in bone marrow, over typical exposure ranges. The model also predicted that the contributions of exposure concentration and duration would be approximately equal over the typical concentration ranges encountered by workers. Short term (within a day) exposure discontinuities played no role in prediction of total bone marrow metabolite concentrations. The authors conclude that the model's predictions are within pharmacodynamic limitations, but they might be effective for determination of exposure metrics for epidemiological studies.