Well-constructed PB-PK models can be powerful tools for interpretation of biomarker data, since they are capable of simulating the portion of the absorbed parent compound that would end up to be its metabolite to be excreted in the urine (or recovered in the blood, etc.). The success of this simulation of the biomarker metabolite would allow us to determine the total amount of absorbed parent compound in the body as well as the timed tissue concentrations in each compartment. This is possible because these mass-balance quantities, including the amount of the biomarker simulated, are kinetically as well as mathematically interrelated to every second of the time. Knowing the total amount of dose absorbed is essential for human exposure and health risk assessment.

Despite its popularity in biomonitoring, urine analysis is not a test without limitations. Routine collection of 24-hour samples in human subjects is usually impractical. Urine analyses for exposure monitoring purposes are accordingly often necessarily conducted on spot specimens. One approach to a more effective interpretation of biomarker data based on spot sample results is hence to simulate the internal dose through use of a PB-PK model (Dong et al., 1996).

Known physiological and biochemical parameters are used in PB-PK simulation. Thus, another advantage is that a different species can be simulated with the model on hand by replacing the appropriate physiological and PK constants, which can be derived from allometric and related equations.