68 CHAPTER 4 The Nano/Bio Interface 4.2.2 Wider Implications It is customary nowadays to take a global view of things, and in assessing the likely impact of nanotechnology on medicine this is very necessary. Nanotechnology is often viewed to be the key to far-reaching social changes, and once we admit this link then we really have to consider the gamut of major current challenges to human civilization, such as demographic trends (overpopulation, aging), climate change, pollution, exhaustion of natural resources (including fuels), and so forth. Nanotech- nology is likely to influence many of these, and all of them have some implications on human health. Turning again to the dictionary, medicine is also defined as "the art of restoring and preserving health by means of remedial substances and the regulation of diet, habits, etc." With this in mind, it would be woefully inadequate if the impact of nanotechnology on medicine were restricted to consideration of the development of the topics discussed in the preceding parts of this section. 4.3 NANOTOXICOLOGY There is currently great concern about the potential adverse impacts of nano-objects