Yes, the EPA - as well as other groups - have raised questions about nanomaterials because some studies show that they can behave unpredictably. Nanotechnology is also being used for some intriguing drug delivery purposes. Surely more work needs to be done to better understand the interaction of biology and nanoparticles. You may have seen that nanosilver was the topic of some EPA focus. In these cases, the reason that the EPA was so focused on them was that these antimicrobial products were not registered with the EPA. All antimicrobials must be EPA registered to be used in the US - and the companies using this technology did not do that. I believe only one nanosilver company is presently registered and selling in the US.
Fortunately, many alternatives to nanotechnology exist to help control bacteria on surfaces - including systems that deliver ionic silver and don’t utilize any nanotechnology.
