It's come up at least twice a year since I've joined the site.I too remember this topic coming up in another thread. I tried searching without luck though. I believe it was a thread that got deleted because people couldn't mind their P's and Q's.
Anyway, honestly this doesn't freak me out though. Think about EVERYTHING we have been exposed to....from the plastic you brush your teeth with, the cans that hold food, the genetic feed that cattle eat, volcano ash, 9-11 debris, gasoline vapors etc.