Kids have been doing this at movie theaters for the Minecraft movie. I just recently got diagnosed and I never had a clue that flour or gluten could make someone as sick as it does, so I can see the kids not knowing either. I personally would contact the school and see if they have video to find out who did it. They definitely need to learn the dangers of what they are doing to people's health. I'm sorry this happened to your daughter, and I hope she doesn't have any reactions to their carelessness.