For thousands of years, rabbis performed a simple procedure to cleanse the wound left by a ritual circumcision. Like Boy Scouts treating a snake bite, they quickly sucked blood from the cut and spit it aside, ostensibly disposing of any harmful impurities. The procedure may seem pure 18th Century, but it is the subject of a clash between religion and science in modern-day New York. Prompted by a child's death, the state health department is developing its first set of safety guidelines on the ritual of oral suction, which was abandoned by most Jews long ago but survived in a...