You know, as funny as it sounds, there may be something to this.
When I was in the military, I had to get trained for chemical attacks. One of the things they taught us was that with attacks birds die off. If you see a bunch of dead birds laying around there's cause for concern.
The only reason I mention all of this is that birds, being so small, would probably be a good indicator of if something is toxic as they can't handle as much as we can. Of course the silicone isn't going to kill a human, at least not after one use, but with years and years of use....there may be some problems.
Just my random thoughts. I thought the silicone sounded like a good thing...now I don't know. I'd love to hear some better thoughts besides the whole "bird-chemical attack" idea.