Le Creuset states right on their packaging that they use 100% FDA approved premium grade silicone. Wilton responded to emails of mine and said that they too use 100% silicone with no other additives. Good to know.
My personal opinion on silicone at the moment is that I wouldn't trust just any store brand silicone product. I also don't completely trust silicone for baking, I've read some concerns about the silicone oil (the oily feel to silicone that makes it non-stick) leaching out into the food, but on the other hand most things I read say that silicone is very inert and will not leach or react. I do love the muffin tin liners, but don't see a need to use other silicone pans for baking in. Silicone spatulas and kitchen utensil type items are great too though. Soothies silicone pacifiers are also the only kind I'll let my babies use because of other pacifiers being made of toxic plastics. Everything in its place I guess.
Anyway, just a bit of my opinion there. I also wanted to clarify that I had emailed Wilton and their silicone is 100% silicone as well, since in my recent post I brought up the question.