Consequent stages of developing a multi-compartmental mechanistic model for chronically inhaled nanoparticles pulmonary retention.

The paper retraces the development of a mechanistic multicompartmental system model describing particle retention in lungs under chronic inhalation exposures. This model was first developed and experimentally tested for various conditions of exposure to polydisperse dusts of SiO or TiO. Later on it was successfully used as a basis for analyzing patterns in the retention of nanoparticles having different chemical compositions (FeO, SiO, NiO). This is the first publication presenting the outcomes of modeling lung retention of nickel oxide nano-aerosols under chronic inhalation exposure. The most significant adaptation of the above-mentioned model to the conditions of exposure to metal-oxide nanoparticles is associated with the need to describe mathematically not only the physiological mechanisms of their elimination but also their solubilization "in vivo" bearing in mind that the relative contribution of the latter may be different for nanoparticles of different nature and predominant in some cases. Using nickel oxide as an example, it is suggested as well that damage to the physiological pulmonary clearance mechanisms by particularly toxic nanoparticles may result in lung toxicokinetics becoming nonlinear.