I am so confused about when and when not to use highlighters. Everywhere I turn, the descriptions and info about use say they are not edible/should not be eaten and should only be used on decorations that will NOT be eaten. Yet, I see them used on piping  and fondant and royal icing accents that clearly will be eaten. I fail to believe piping and trim painted with highlighters are scraped and picked off before eating.

I want to use highlighters on piping because it gives the most realistic metalic look. So, what do I do?

There are edible products available now. 

Read this http://www.countrykitchensa.com/whatshot/dusting_powders.aspx

I happily sacrifice the most realistic look for safety. That's just me.

One of my students insisted that her glitzy non-toxic cupcakes were totally safe to eat. It's unfortunate, but many people think that non-toxic means edible.   

I see many cakers do this and I too fell that it is to save money on the item they are decorating.  Just because it says non-toxic and someone eats some of the "non-toxic" items they may not have a problem.  However, another person at the same event may get seriously ill.  I would stick with the items that are truely edible.

Thank you, everyone. I have stayed away from highlighters for the very reasons you all state about edible versus non-toxic. I want as many edible decorations as possible and, in my opinion, piping and accent decorations should not have to be pulled off to eat the cake. A lot of the fun of a fancy cake is eating the decorations. Besides, I know that even if advised to do so, many people will not remove them. Case in point - silver dragees.