Major food allergens:
The protein found in milk, eggs, fish, Crustacean shellfish, tree nuts, wheat, peanuts, and soybeans.
FDA's What you need to know. These allergens are packaged in our plant: peanuts, all tree nuts, almonds, walnuts, pecans, soybeans, wheat, milk powder, and egg powder allergens.
Although most food allergies cause relatively mild and minor symptoms, some food allergies, mainly peanut, can cause severe reactions, and may even be life-threatening for some individuals.
FDA has found that: "unintentional cross-contact of foods with major food allergens may occur at almost any step of the manufacturing process and for various reasons. Cross-contact can occur due to allergens in raw ingredients or in processing aids, allergens in reworked product, and allergen carry-over from the use of shared equipment. Such potential sources of unintentional allergen cross-contact exist regardless of the manufacturer's size or food product."
Due to the above reasons and possible air born contamination, traces of allergens are possible in all foods sold. So if exposure to peanuts / tree nuts or the air around peanuts/tree nuts results in a life-threatening anaphylactic reaction it may be best to purchase only from non peanut / tree nut processing/selling companies. Other individuals with allergies may find it fine to purchase foods containing no allergen ingredients without concerns of trace contamination.
Food-allergy.org How to survive with multiple food allergies and thrive again.
Lectin intolerance often associated with food allergies has also been linked to many degenerative diseases and many common symptoms prevalent today. Following a lectin elimination based diet program may be more effective than an allergy diet program. A very comprehensive technical article, The Lectin Report, has easy to understand programs to eliminate lectins.
This is only a guide and should not be relied upon as professional advise. If needed seek proper consultation from a health professional.