About 7 million Americans are allergic to one type of food or another--from nuts to milk to wheat to shellfish. This year, some 30,000 will develop reactions severe enough to send them to the emergency ward, and about 200 will die--often after their throats close up and their blood pressure plummets.
But you don't have to eat anything to have an allergic food reaction. Some people are so sensitive that touching food briefly or inhaling microscopic particles is enough to do the trick. "It can take a surprisingly tiny amount to elicit a reaction," says Dr. Suzanne Teuber, an allergist at...