This decade has seen revolutionary developments in the field of nanotechnology with newer and diverse applications of nanoparticles (NPs) appearing every day. However, there are limited data about the toxicity of nanoparticles and their fate in biological systems. Inhalation, ingestion, and dermal penetration are the potential exposure routes for nanoparticles, whereas particle size, shape, surface area, and surface chemistry collectively define the toxicity of nanoparticles. Increased production and intentional (sunscreens, drug delivery) or unintentional (environmental, occupational) exposure to nanoparticles are likely to increase the possibilities of their adverse health effects. It is crucially important that novel nanomaterials must be biologically characterized for their health hazards to ensure risk-free and sustainable implementation of nanotechnology.