The biomedical literature and popular media are full of upbeat reports about the health benefits we can expect from medical innovations using nanotechnology. Some particularly enthusiastic reports portray nanotechnology as one of the innovations that will lead to a significantly extended human life span. Extreme enthusiasts predict that nanotechnology “will ultimately enable us to redesign and rebuild, molecule by molecule, our bodies and brains….”Nanomaterials have special characteristics that could contribute to improved patient care. But the same characteristics that make nanotechnology (...) promising also present risks to humans exposed to nanomaterials. A failure to appreciate these risks could jeopardize the research effort. As others have pointed out, if nanomedical interventions produce unexpected human harm, a loss of public and government support for nanomedicine is likely to follow.Like other forms of medical innovation, novel nanomedical interventions require human testing to evaluate their safety and effectiveness. (shrink)