Genotoxicity of engineered nanomaterials: A critical review

In view of the fast-growing industrial applications of engineered nanomaterials (ENMs), the evaluation of their genotoxic potential and of their mode of action is a necessity to conduct adequate hazard/risk assessment and to produce safer and sustainable ENMs. This review aims at: (i) Providing an evaluation of in vitro and in vivo genotoxicity data available for ENMs, and (ii) proposing minimal criteria for conducting nano-genotoxicity assays. The possible modes of action of ENM (i.e., generation of reactive oxygen species (ROS) and mechanical interference with cellular components) and the potential cellular targets are discussed. The available studies are evaluated on the basis of specific quality criteria after categorisation according to ENMs type/size investigated. No definitive conclusion can be drawn concerning the genotoxic activity of ENMs, essentially because of the limited number of data, incomplete physico-chemical characterization of ENMs examined and shortcomings in experimental approaches. This evaluation revealed gaps to be considered in future studies (e.g., one-sided approach focusing mainly on ROS as mode of action) and the need to develop adequate positive controls for genotoxicity assays when conducted with nanomaterials.