One more link - I hate to cite Reader's Digest, but this looks pretty good at a cursory glance: 7 First Aid Standbys You Should Avoid [link]
CUTS AND SCRAPES Hydrogen Peroxide, Iodine, Rubbing Alcohol, Mercurochrome When the skin isn't broken, it's hard to beat iodine for killing bacteria. That's why doctors use it to clean an area before surgery. But when there's a cut, says dermatologist Robert Kirsner, a spokesperson for the American Academy of Dermatology, full-strength iodine, hydrogen peroxide and rubbing alcohol can be toxic to skin cells, impeding healing. The chemical reaction (and bubbling) that occurs when hydrogen peroxide hits the skin isn't only cleaning the wound -- it's killing healthy cells. And that stinging from the rubbing alcohol? This stuff hurts because it's wiping out healthy tissue.
Putting iodine on cuts and wounds kills bacteria, says VanRooyen, but it won't clean the wound. "You want to protect the good tissue, and iodine doesn't do that." Mercurochrome also kills bacteria, but as the name suggests, it contains mercury, which is toxic, and not generally recognized as safe, says the FDA. Today, doctors don't use Mercurochrome.
Better Bet Remarkably, cleansing a wound has become much simpler: "The most effective way to get rid of debris and bacteria without damaging healthy tissue is flushing the wound out with water," says VanRooyen. Put the wound under a faucet, or spray it with the nozzle on the kitchen sink. Flush it with water to clear it of all debris. If you are worried about the bandage sticking to the wound, consider using an antibacterial ointment that contains bacitracin or neomycin to keep the area lubricated.
I got WFA certified and read Where There Is No Doctor cover-to-cover before going into Peace Corps, in case you are wondering why I know this random stuff. Also got my nose pierced a few years ago, hence the piercing aftercare.