When DS was in kindy, when kids were messier, my DH or I went on all the field trips. Since then, I've tried to go on as many field trips as possible, because I like to get to know his teachers and classmates and it's fun, but I haven't been as worried once I got to know that teacher and they understood his allergies. I sign every permission slip with "as long as his meds are with him". What makes me most comfortable is that we still send all his own food and drinks (he's in 4th grade now). He sits with his class in the lunchroom now. His friends know about his allergies, too.

Depending on how sensitive your kiddo is, something else to check into is whether the rooms your kiddo will be in will have his allergens. (E.g., specials, gym, other classrooms, library.) When I picked up my son from an afterschool activity in the library, I found little cups of peanuts in there. The kids from the afterschool care were allowed to bring their snacks into any of the afterschool activity rooms. (Since I brought this up, they have since changed the plan so that the afterschool care kids must eat their snacks in the lunchroom only.)