Here is a blog post on the safety worries on Nanotech:
Article from Slashdot.org:

Nano Safety Worries Scientists More Than Public

Posted by CmdrTaco on Monday November 26, @10:00AM
from the what-aren’t-they-telling-us dept.

Nanotech Coward writes “The unknown human health and environmental impacts of nanotechnology are a bigger worry for scientists than for the public, according to a new report in the journal Nature Nanotechnology. The new report was based on a national telephone survey of American households and a sampling of 363 leading U.S. nanotechnology scientists and engineers. It reveals that those with the most insight into a technology with enormous potential — and that is already emerging in hundreds of products — are unsure what health and environmental problems might be posed by the technology.”