Nanotechnology is going to change our lives in many different ways since its applications span from electronics to medical treatments. However, great concerns about nanomaterials' hazardous effects on the environment and human health are increasing as nanotechnology flourishes. Besides the benefits promoted by intentional use, worries mainly concern misuse or, worse, non-intentional exposure. In this contribution we would like to briefly summarize findings on skin penetration of nanoparticulate nanomaterials, herein indicated as nanotechnological nanoparticles, and to brain-storm on their potential ability to generate toxic effects.