When it comes to food scientists always do their best to ensure there are no health risks. We are getting better and better at avoiding these risks. However, it is an important question. Can we know the long term effects? And perhaps another point, what happens when there is nanotechnology in food, and that nanotechnology is patented. Well then the food is patented! Just like genetically modified (GM) foods I think the biggest worry is not health, but copyright law!
Before anything would ever get to market is has to be tested over and over again to make sure it is safe. Silver nanoparticles could be used in some foods to stop it going bad as nanoparticles are antibacterial and stop the food from and would stop the food from spoiling.