dr. ruchi gupta is the lead author of the study. she's a pediatrician at children's memorial hospital and an associate professor of pediatrics at northwestern university school of medicine. . >> the first question that comes to mind is that this never used to happen, at least it didn't seem like it we're talking about $6 million children with food allergies y so many now? >> so that's a great question. and there's a lot of theories on why. but what is really important is that it does exist and this one out of every 13 kids, two out of every classroom in america a lot of kids have food allergy and a lot have severe food allergy. >> how did you come up with these numbers? >> we surveyed 40,000 family ass can cross the united states to get these numbers. and we were able to ask food allergists specific questions like what type of food allergy they v what type of reactions, how it was diagnosed. and this allowed us to paint a really good picture of what food allergy looks like today. >> so tell me what the answers were. what kind of foo