pesiticides or other chemicals in food allergy test samples?

I was wondering if anybody knows if the food samples used flor allergy testing is likely to be contanimated by pesticides or other chemicals which the food may have been exposed to?

In my particular case, I thought I was allergic to specific fruits; however, when I switched to organic fruits, I no longer had any allergic responses, which led me to believe that I may have had reactions to common pesticides or other chemicals which the fruits were exposed to, rather than the fruit itself.

My son is undergoing food allergy testing, and I'm curious how likely it is for the results to be similarly misleading if he tests positive for reasons other than the food itself.