They don't contain poisonous materials right...?
Yes. Just a slight touch of hand of them will kill you within 5 minutes. If I were you, I'd be careful.
I have no sources to back this up, but my guess is that they're made either from completely safe materials or materials that aren't entirely safe, but their detriment to your health is on the same level as many of the plastics that you come in contact with on a daily basis, which is to say: long-term exposure probably upsets your hormones somewhat and possibly causes other disturbances (but again, this comes with the territory of living a 21st century existence anyway, so there's no much point in stressing about it).
24 years old