Emerson White wrote:It is not sterile. Blood is sterile inside your veins (mostly), but anything that opens to the outside world (other than your urinary tract is unlikely to be sterile, that's why TSS happen, Staph. naturally living in the body feeds off the blood in the tampon and populations build to massive levels over the course of 12 hours and the toxins produced go in through the mucus membrane. Incidentally everyone is constantly shedding retroviruses, even in their blood. They are everywhere, its best to avoid sharing bodily fluids with too many people.