There is evidence, to date, that nanomaterials have different effects on human and animal health from those of micron-sized materials. Typically nanomaterials possess specifical properties — chemical, optical, magnetic, biological — that may lead in the human body to a response that is different and not directly predicted from the chemical constituents and compounds. For example, even a traditionally inert compound, such as gold, may behave differently in the body when it is introduced as a nanomaterial. Therefore, the world’s scientists, industries, and governments are beginning to take a critical look at nanotechnology and to develop a research agenda for addressing key issues related to the impact of nanotechnology on health and environment.