Biological impacts of TiO2 on human lung cell lines A549 and H1299: particle size distribution effects

Increasing use of titanium dioxide (TiO₂) nanoparticles in many commercial applications has led to emerging concerns regarding the safety and environmental impact of these materials. In this study, we have investigated the biological impact of nano-TiO₂ (with particle primary size of 20 nm Aeroxide P25) on human lung cell lines in vitro and also the effect of particle size distribution on the particle uptake and apparent toxicity. The biological impact of nano-TiO₂ is shown to be influenced by the concentration and particle size distribution of the TiO₂ and the impact was shown to differ between the two cell lines (A549 and H1299) investigated herein. A549 cell line was shown to be relatively resistant to the total amount of TiO₂ particles uptaken, as measured by cell viability and metabolic assays, while H1299 had a much higher capacity to ingest TiO₂ particles and aggregates, with consequent evidence of impact at concentrations as low as 30–150 μg/mL TiO₂. Evidence gathered from this study suggests that both viability and metabolic assays (measuring metabolic and mitochondrial activities and also cellular ATP level) should be carried out collectively to gain a true assessment of the impact of exposure to TiO₂ particles.