Is oral sex dangerous?

Some risk . . . . According to the centers for disease control & prevention, "in addition to hiv, other stds can be transmitted through oral sex with an infected partner. Examples of these stds include herpes, syphilis, gonorrhea, genital warts (hpv), intestinal parasites (amebiasis), and hepatitis a." for infomation on safe sex, see: http://www.Cdc.Gov/hiv/resources/factsheets/oralsex.Htm.
No, provided... If your partner has an STD, all can be transmitted! The only safe oral sex is qwith A PARTNER WHO DOES NOT HAVE AN STD!
Not Really. You still have the risk of sexually transmitted diseases (same as intercourse) but really should not have any additional risk beyond that. Practice safe sex regardless of what you do.
Yes. The enzymes in saliva can cause skin damage and let infections occur on the genitals. Quite a few std's can be spread by oral sex.