Comparison of human lung dosimetry models: implications for risk assessment

In this study we have compared several human lung dosimetry models and predicted particle burdens in the lungs and lymph nodes of humans with working lifetime exposures to airborne particulates. The focus of this study was the clearance and retention of poorly soluble particles in the alveolar (gas exchange) region of the lungs. The models evaluated include those developed for exposure to radioactive particles and coal mine dust and a rat-based overload model extrapolated to humans. Results show that the predicted mean particle burden in the lungs varies by as much as two orders of magnitude among the different models. These findings indicate that risk estimates for particle-related lung diseases in humans could differ considerably depending on the choice of lung dosimetry model. Further evaluation is needed to investigate which kinetic model features best predict human lung particle burdens over a range of particle sizes, types and exposure levels and to investigate issues of variability and uncertainty.