The only problem is that I THINK they may be untempered glass -- but I'm not sure how to tell for certain if it is tempered or untempered. (Tempered is usually marked as such in the US but these are from who knows where). Untempered glass breaks easily.
If you have a set of polarized lenses (like the glasses from a 3D movie), I think you can use those to determine if the glass is tempered or not. I'm not certain of the specifics offhand, but I imagine putting the glass twixt the lenses, and looking through while rotating one of the lenses should give some indication.
Anyways, I doubt they are tempered, something that size and shape wouldn't really need the extra strength, and the shape will add a lot of strength compared to a flat sheet.