Nanotechnology exciting but risky - Could the environment become too clean? [1] - Columbus Dispatch, USA
One popular use of nanotechnology is adding an ultrathin silver coating on kitchenware such as knives and forks so that bacteria can't stick to the surface. But not all bacteria are bad. Some actually are crucial to building the body's immune system. If the environment becomes too clean and too antiseptic, experts say, there can be health hazards. There is a risk if bacteria develop a resistance to antibacterial materials.
Silver nanoparticles are of special concern. These germ-killing particles are used in shoe liners, food-storage containers and washing machines, among other things.

Misplaced Principles for Nanotechnology in the Environment, Health and Safety [2] - Tech Talk, USA
Bizarrely in the first area “Purpose”, the critical dimension of protecting human health and the environment gets relegated to second fiddle behind being “cognizant of the potential benefits of nanotechnology, including health, economic and environmental benefits”.
It’s hard to argue to throw out the baby with bathwater when addressing health concerns about nanotechnology by just suspending all nanotechnology development. But health and safety are first, preserving the so-called “nanotechnology industry” is further down the list, if on it at all.