well, the original material that comes in the carts is just simple poly fill. check the craft stores or even walmart for 100% poly fill batting, and just check the package and make sure there are no additives or anything, or any chemical treatments. some companies may add some like, fire ......ant type things to them and you don't want that, just plain standard 100% poly fill.
there's also a type of fish tank filter that is essentially the same thing, but that would take some time to dig out. if you check around the mod threads you'd have better luck.
the inherent danger is simply if you're using something like cotton balls or other materials that may have plastics, the atomizer can heat those plastics and you'll end up inhaling those chemicals. that...is bad
