Some vapers do use bleached cotton. It's really up to you & what you feel safest using... I've used cotton-balls for many many years now with no issues. If you find a product that does say unbleached+organc-cotton, then all the better, as that cotton product is unbleached & organically grown. The truth is, any cotton plant that becomes a white poofy cotton-ball, is boiled at high-temps prior to becoming that bleached white cotton-ball. so i really have no issue using cotton balls. (tho, u can get natural/organic cotton-balls from most drug-stores, like CVS and Walgreens)
As-long as those facial pads have no chemicals for cleaning the face, those would be perfect, assuming they will break-apart long enough to fashion a wick from them. You can also use cotton yarn, as I've said above. (Peaches N Cream cotton yarn from Walmart is unbleached+organic) there are really plenty of cotton products that you could technically use for wicking safely. Cotton Q-tips, cotton pads, cotton gauze. Anything that does-not have chemical within it or sprayed upon it. MOST bleached white cotton is going to be sterile, just because they do boil the cotton to manufacture these products, and the fact that cotton is used in the beauty/healthcare industries, which demand a clean/sterile product.
i mean, i can't guarantee anything but what I am trying to say to you, is that ME personally? I both use & approve-of the use of bleached cotton, and organic unbleached/uncolored cotton. you can most-likely find a big bag of medical supply cotton online that would probably be guaranteed sterile. some people use synthetic cotton, known-as rayon, i believe. it's a fantastic wicking material. (in-fact, rayon beats-out organic cotton and competes neck-in-neck with japanese cotton, in wicking ability)
so, i mean, you can use anything you feel comfortable using, my brother.