Safety of Loose Icing

I'm not an expert, but I don't think safety would be a problem if you are making the royal icing with meringue powder and not egg whites.  There are no ingredients that could "turn" like there are in buttercream.

If you're using meringue powder and not raw egg whites, then there's no potential carrier of salmonella (which is carried in raw, not pasteurized or dehydrated, eggs), but you can still cross-contaminate (introduce bacteria to) any food product if you handle it improperly (i.e., don't wash hands, get something else in it). Products with high concentrations of sugar can suppress bacterial growth but they are never a complete preventative. Proper handling to avoid cross-contamination is always important. In this case, if you handled everything carefully, there's probably not much to worry about.

If you're serving the public, you should really take a food safety and sanitation course. (Most, if not all, US states require it, in fact.) Here's a link to tell you more: http://www.servsafe.com/home 

Thank you so much! I just noticed the labels on the meringue powder I use are pretty minimal, so I just wanted to make sure I wasn't missing anything. Thanks again!