Titanium dioxide nanoparticles - physicochemical characterization and cytotoxic risk

Titanium dioxide (TiO₂) nanoparticles (NPs) are incorporated into numerous consumer products yet data as to potential adverse health effects remains inconclusive. In this paper we physically characterize 16 nanoforms of TiO₂ from different manufacturers of different size, crystalline structure and surface chemistry. Physical measurements of the particles were performed and compared with those provided by manufacturers revealing several discrepancies. We then examined the biological effects of these particles in cell culture in 3 commonly used cell lines for testing materials. We were unable to validate that anatase particles are more cytotoxic than rutile particles as has been reported, and generally found that the particles produced few effects and no significant production of reactive oxygen species under the conditions used. While some particles do exhibit a dose dependent cytotoxicity that increases over time in some cell lines, the effects were not consistent between cell lines and do not appear to be linked to crystalline structure or any of the specific physical characteristics that were measured including, size, charge and surface composition, nor a correlation with the production of reactive oxygen species.