Concerns have been raised by many about how safe it would be to release carbon nanotubes into the environment. Some of this is overblown I think as nanotubes occur in small quantities naturally (as a byproduct of a wood fire, for example). Nevertheless, I think the concerns are real and I’m glad that research is ongoing on this subject, especially as one sees stories now (like here) about lung problems being perhaps associated with very small particles jettisoned into the air by combustion engines.
One recent studyfrom Stanford shows that nanotubes in the bloodstream can exist safely within the body and are excreted in the “normal way”. Not only that, but nanotube based delivery systems for medicines hold much promise to treat human health problems.
But I’d still like to see some studies about what happens when nanotubes are inhaled. I’m sure there are nanotube development researchers who are now unwittingly being guinea pigs in this area as they work to create nanotube-based materials (like tethers). At some point if/when nanotube strength gets to the point where a Space Elevator is really possible, this is going to be one of the concerns raised. Of course, this theoretical release of nanotubes into the environment as a potential pollutant will have be balanced against the very real pollution which is a byproduct of today’s rocket programs.
(Hat tip to Andy Price for pointing out the Stanford Article. Graphic from here.)