TiO2-NPs and cadmium co-exposure: in vitro assessment of genetic and genomic DNA damage on Dicentrarchus labrax embryonic cells

The increased titanium dioxide nanoparticles (TiO2-NPs) spread and their interaction with organic and inorganic pollutants arouses concern for the potential hazards for organisms and environment. This study tested in vitro the genotoxic effects of TiO2-NPs (1 μg/mL) and cadmium (Cd) (0.1 μg/mL) co-exposure using Dicentrarchus labrax embryonic cells (DLEC) as experimental model. The genotoxicity tests (Comet assay, Diffusion Assay and Random Amplification of Polymorphic DNA (RAPD-PCR) were conducted after 3, 24 and 48 hours of exposure to TiO2-NPs and Cd alone and in combination. The results showed that the percentage of DNA damage and apoptotic cells increases following 48 hours TiO2-NPs exposure, while DNA instability was detected for all the times tested. Cd induced genotoxic effects starting from 3 hour-exposure and for all the treatment times. Cd + TiO2-NPs co-exposure did not cause any genomic damage or apoptosis for all the exposure times. The possibility that Cd and TiO2-NPs form aggregates no longer able of penetrating the nucleus and damaging the genetic material is discussed.