TITANIUM DIOXIDE AND ZINC OXIDE NANOPARTICLES ARE NOT MUTAGENIC IN THE MOUSE LYMPHOMA ASSAY BUT MODULATE THE MUTAGENIC EFFECT OF UV-C-LIGHT POST TREATMENT

There are no studies in the literature on nanomaterials (NMs) using gene mutation approaches in mammalian cells, which represents an important gap for genotoxic risk estimations. To fill this gap, mouse lymphoma L5178Y Tk(+/-) assay (MLA) was used to evaluate the mutagenic effect of titanium dioxide and zinc oxide nanoparticles (NPs). Two different NP sizes (between 1-50 and 50-100 nm) of each NP were used. The results indicate that both the selected NMs and their microparticulated forms do not have mutagenic effects. Nevertheless, pre-exposure to these NMs reduce the mutagenic effect of posterior UVC-light exposure, in an indirect concentration-effect relationship. As such, cells previously exposed to low concentrations of the selected NPs show better protective effects against posterior exposure to UVC-light. These in vitro results, obtained from mouse lymphoma cells, support the reproduction of the current literature date on these NPs' genotoxic potential as well as to focus on the discussion on the benefits/risks associated with their use in photo protection sunscreens.