As impressive as nanotechnology might be, there are also potential disadvantages of nanotechnology. Some of the problems with nanoscience are practical while others fall under the ethical realm.
Practical problems can include everything from the need for mass produced forms of nanotechnology that may or may not be possible.
Read more: http://nanogloss.com/nanotechnology/the-potential-disadvantages-of-nanotechnology/#ixzz3kwNQBL6r