Danner is right, this isnt new news. After long term use the plastic used in the newer (meaning clear, or colored clear hard plastic) releases toxins into whatever liquid your drinking.
I've chosen to take my chances with it though, i guess i just like to live dangerously.
Oh, and another thing. The Sigg bottles are nice, but arnt nearly as useful as Nalgene's. You can see into a Nalgene, which is useful for odvious reasons. Additionally the widemouth bottle neck allows you to mix food in it if your out camping; it really is the all in one meal utensel.
Im not hating on Sigg's, they're superstylie and tough, i just dont think they're as functional.