K.,
As the mom of a child with severe nut allergies, I thank you for being so sensitive and thoughtful about keeping kids with allergies safe from exposure.
Unfortunately, while my daughter's classroom is completely nut-free, the cafeteria isn't, and she must sit in a segregated area to eat her lunch. Last spring she was exposed to nuts AT A SCHOOL POT-LUCK from a small cookie from the "nut free" table. Apparently this parent didn't realize that almond extract (in addition to the almond itself) was also an allergen. It was the most severe reaction my daughter had to date and required TWO epi-pen injections and 7 hours in the ER to bring it under control. I don't have to tell any parent that when your child can't breathe, nothing else matters! She does still eat school hot lunches because the staff is small and they have all been thoroughly trained about cross-contamination. Most days she brings lunch from home. Fortunately, she is also vigilant about anything she consumes whether it's at school or in a restaurant -- and she wouldn't dream of trading snacks or even taking a bite of someone else's lunch.
Something as simple as tiny peanut butter cracker CRUMBS on the fabric of a recliner (we weren't aware they were there)caused the back of her legs to break out in hives top to bottom. Some people are under the mistaken impression that hives are no big deal because they can be treated with Benadryl. The hives are just a precursor to what could be a life-threatening reaction. Door knobs, public toilets, movie theater seats and the like are all possible sources of exposure, so we reinforce a lot of handwashing (and surface disinfecting)-- especially before eating! Gratefully, no one is permitted in her classroom without washing their hands upon entry (kids and adults alike).
All of the responses I've read correspond with what I know about reading labels for nut content. We have a large healthfood store nearby and they are exceptionally helpful if I have any question about the contents of a particular product. Most of the products they sell have a very simple list of ingredients (very few, if any, preservatives), so my experience has been that it's much easier to determine questionable content.
Thank you again for your pro-active stance on this important issue! I wish you and your son good health and much happiness. Have a blessed Thanksgiving!