Book excerpt: This book provides the detail information about nanoparticles, their types, characterization techniques such as TEM, FESEM, AFM, XRD etc. nanogenotoxicity, metal and metal oxide nanoparticle’s toxicity, physical and chemical characterization of nanomaterials, entry routes, cell-nano interaction studies, possible impacts to the human kind, and on the methods of evaluating the toxicity. It puts together comprehensive and up-to-date information about sustainable approaches in making an eco-friendly environment using advanced nanotechnologies. It educated readers about the new frontiers and scope of employing various state-of-art nano-technologies to clean-up and save our environment. This book will be of interest to teachers, researchers, environmental biotechnologists, capacity builders and policymakers. Also the book serves as additional reading material for undergraduate and graduate students of agriculture, environmental sciences, environmental engineering and biotechnology.