Genotoxic and carcinogenic potential of engineered nanoparticles: an update

Nanoscience and nanotechnology have seen an exponential growth over the past decade largely due to the unique properties of engineered nanoparticles (ENPs), advances in ENP synthesis, and imaging or analysis tools. The unique properties such as high surface area to volume ratio, abundant reactive sites on the surface, large fraction of atoms located on the exterior face have made these novel materials the most sought after for consumer and industrial applications. This significant increase in the ENP containing consumer products has also enhanced the chances of human and environmental exposure. Humans get exposed to ENPs at various steps of its synthesis (laboratory), manufacture (industry), use (consumer products, devices, medicines, etc.) and through the environment (contaminated water, aerosolized particles, and disposal). Such exposures to ENPs are known to induce genotoxicity, cytotoxicity, and carcinogenicity in biological system. This is attributed to several factors, such as direct interaction of ENPs with the genetic material, indirect damage due to reactive oxygen species generation, release of toxic ions from soluble ENPs, interaction with cytoplasmic/nuclear proteins, binding with mitotic spindle or its components, increased oxidative stress, disturbance of cell cycle checkpoint functions, inhibition of antioxidant defense, and many others. The present review describes an overview of in vitro and in vivo genotoxicity studies with ENPs, advantages and potential problems associated with the methods used in genotoxicity assessment, and the need for appropriate method and approach for risk assessment of ENPs.