Assessing the airborne titanium dioxide nanoparticle-related exposure hazard at workplace

The purpose of this study was to investigate the effects of size and phase composition on human exposure to airborne titanium dioxide (TiO2) nanoparticles (NPs) at workplaces. We reanalyzed published data of particle size distribution of airborne TiO2 NPs during manufacturing activities and linked a physiologically based lung model to estimate size- and phase-specific TiO2 NP burdens in target lung cells. We also adopted a cell model to simulate the exposure time-dependent size/phase-specific cell uptake of TiO2 NPs in human dermal and lung cells. Combining laboratory, field, and modeling results, we proposed two major findings: (i) the estimated median effective anatase TiO2 NP concentration (EC50) for cytotoxicity response on human dermal fibroblasts was estimated to be 24.84 (95% CI: 7.3-70.2) nmol mL−1 and EC50 estimate for inflammatory response on human lung epithelial cells was 5414 (95% CI: 3370-7479) nmol mL−1 and (ii) packers and surface treatment workers at the TiO2 NP production workplaces are unlikely to pose substantial risk on lung inflammatory response. Nevertheless, our findings point out that TiO2 NP production workers have significant risk on cytotoxicity response at relatively high airborne anatase TiO2 NP concentrations at size range 10-30 nm.