On the other hand, the study by Wan et al. revealed that TIO2 nanoparticles, which are widely used in studies modeling lung effects of environmental nanoparticles, did not cause an increase in the ROS generation in the exposed A549 cells, and the consequences of the ROS generation, i.e., DNA damage, the phosphorylation of histone H2AX (γ-H2AX), Rad51, and p53, or the phosphorylation of ataxia telangiectasia mutant were seen after the exposure to cobalt nanoparticles and reversed by NAC. Here, RAD51 is linked to telangiectasis.