Toxicity of Nanomaterials: Exposure, Pathways, Assessment, and Recent Advances

Growth in production of manufactured goods and the use of nanomaterials in consumer products has mounted in the past few decades. Nanotoxicology or toxicity assessment of these engineered products is required to understand possible adverse effects and their fate inside the human body. The present review is a one stop assessment intended to be a state of the art understanding on nanotoxicity. It provides a summation of the various kinds of cell death and also discusses the different types of toxicities along with their studies. The review discusses the physiological impact imparted on cells (reactive oxygen species generation and the resultant oxidative stress, inflammation, and other nonoxidant pathways). Moreover, it discusses the different physicochemical properties of nanomaterials (size, morphology, surface charge, and coating) governing the cytotoxicity properties. It also details the major pathways of nanomaterial uptake in cells and their outcome. Additionally, it also discusses the possible methods for human exposure to nanomaterials (skin, respiratory tract, gastrointestinal tract, blood brain barrier, liver, and spleen). Furthermore, an entire new section is contributed in discussion of all possible types of assays (cytotoxicity, cell proliferation, and genotoxicity assays). A summarized discussion of the recent advances on in vitro, in silico, and in vivo studies of nanomaterials (metal, metal oxides, carbon nanotubes, graphene, and other novel materials) is made. The review also provides a brief account of the safety guidelines for handling nanomaterials. Finally, the uses of engineered nanomaterials in commercial products are discussed in detail.