Every silver lining has a cloud behind it. There are perhaps thousands of prospective uses for nanotubes, from medicine to engineering. We may have to work out exactly where the line is. Asbestos was once considered an essential fire retardant. After the dangers that have been discovered recently, we've found that there are very few places it can be used safely. Asbestos is inorganic, and will not break down, however Carbon is the basis for organic chemicals, with which we are more likely to be compatible. There will be places that nanotubes will not break down quickly. Perhaps not until long after we are dead. Maybe there is a microorganism natural, or designed, that will clean them up. Meanwhile it's good the alarm bells have started to ring early, so, now wary of the dangers, we can do more specific investigation and learn exactly where they are safe to use. If there are any doubts they should be resolved first

If the military holds an interest in the development of the technology, a few alarm bells won't stop them.