Overall, nanotechnology will probably offer environmental benefits compared with many existing technologies. Nanotechnology may be used to replace existing technology which has known environmental and toxicological risks.
Although economic progress often comes at the expense of the environment, nanotechnology may offer an exception to the rule. Nanotechnology will involve materials that are more expensive than conventional materials on a per/pound basis, thus it's possible to manufacture high value goods using relatively small amounts of energy and raw materials. Nanotechnology may indeed be an exception to the idea that a rosy economic climate and an unsullied wilderness are rarely comfortable bedfellows.
Trends in materials manufacture has been toward increasing commoditization of materials. This translates to producing the same volume of goods less expensively. It is possible that some of the costs of commoditization have not been adequately accounted for, but that is beyond the scope of this FAQ.
When dealing with an industry producing commoditized materials, companies quickly determined that in order to generate more profits, larger volumes of goods must be produced. Nanotechnology may reverse some of this economic trend, since these materials are higher value added goods. In other words, it may be possible to increase profits while producing smaller volumes of goods. In general, the smaller the volume of goods produced, the smaller the impact on the environment.
At this point, environmental studies on nanotechnology are few and far between, although a recent UK government study suggested that existing regulations were often successful at evaluating new products based on nanotechnology.
Unfortunately, not all environmental studies have been carefully done and several of the existing studies are of dubious value. Perhaps surprisingly, some studies are suggesting that nanomaterials may not be as rare in nature as one might think. Nanomaterials such as montmorillonite are a type of clay, while nanotubes and fullerenes are components of soot. If nanomaterials are found in nature, then evaluating their toxicity becomes much more straightforward, since it appears likely that most nanomaterials will be relatively benign.
Nanotechnology in Popular Fiction
Since scientists haven't done a very good job of explaining what nanotechnology is, it's not surprising that many people have turned to fiction to get a handle on the topic, perhaps even unknowingly. While some fiction weaves fact and imagination together seamlessly, other fiction is based largely on the author's imagination.
This concept of tiny robots inside us is one of the most pervasive definitions of nanotechnology I've come across. The earliest version of this idea I've seen was in a "Star Trek: The Next Generation" episode involving what Data (the android) termed "nanites". Like many of the inventions of Star Trek such as warp drive, phasers, transporter beams, replicators, etc., the concept entered the realm of popular culture. While the concept of "nanites" may intrigue the imagination, it's quite far from reality in the 21st Century - and I suspect, the 24th Century as well.
While the nanites in Star Trek were benign, Michael Crichton took a similar concept and put a decidedly more chilling aspect on his nanoparticles in Prey. For those who haven't read the book, it's the Frankenstein story updated to the 21st Century. A small company, driven by greed and deadlines, is attempting to develop sentient nanoparticles that can communicate with each other. Needless to say, things don't go quite as planned. In a Michael Crichton story - what did you expect?
Some people in the field of nanotechnology have attempted to defuse the danger of nanotechnology by pointing out that the technology to produce the nanoparticles described in Prey (or Star Trek, but those nanites were far less scary) doesn't exist yet. This is something of an understatement since it is highly unlikely that such sentient nanoparticles could ever be developed. Eric Drexler has also reexamined the postulates behind the "gray goo" he suggested could be highly dangerous and found these postulates wanting. A little reflection on the power requirements and the complexity requirements of the "nanoparticles" in the book or most other popular fiction will show why these scenarios are effectively impossible. The energy needed to move the mass of the nanoparticles in Prey around would require a lot more than is available in sunlight - even with a 100% efficient solar cell. Furthermore, energy storage in a nanoparticle is problematic, since energy storage systems require a number of different parts. Using biology as a guideline may be helpful - viruses don't have energy storage systems, they need to rely on their hosts machinery to provide the energy for replication. So while it may be possible to develop complex devices using nanotechnology, these complex devices are probably going to be larger than the nanometer size range. MEMS and now NEMS are flourishing disciplines, but neither is necessarily dependent on the quantum materials which are the basis of nanotechnology.