Peanuts in the air - clinical and experimental studies

Allergic reactions to food allergens usually occur after ingestion. However, fear of reactions to airborne peanut is a common concern for people with peanut allergy. There are no scientific reports on severe reactions with airborne peanut allergen.

To investigate the occurrence of allergic reactions in peanut-allergic children undergoing airborne peanut challenge and to determine levels of airborne peanut protein in a separate experimental evaluation.

Eighty-four children with peanut allergy underwent an airborne peanut challenge, 0.5 m from a bowl of peanuts for 30 min under controlled conditions. In a separate experiment, airborne peanut proteins from roasted and dry-roasted peanuts were collected at varying distances and at varying times with an electret SensAbues filter connected to an air pump. Collected airborne peanut proteins were extracted, dissolved and detected by ELISA. Basophil activation test was used to confirm biological activity.

No moderate/severe allergic reactions to airborne peanut allergens were observed. Two children (2%) had mild rhino-conjunctivitis which required no treatment. The IgE-antibodies to peanut or Ara h 2 did not predict a reaction. In the experimental set-up, biological active peanut proteins were detected, in a very low amount, in median 166 ng/ml for dry-roasted and 33 ng/ml for roasted peanuts and decreased dramatically when the collection occurred at a greater distance (0.5-2 m) from the peanut source. Increased exposure time did affect the amount of collected peanut protein at 0 m, and the highest median was obtained after 60 min (p = .012); for time trend p = .0006.

Allergic reactions to airborne peanut proteins are rare and cannot be predicted by high levels of IgE-antibodies to peanut or Ara h 2. Only small amounts of biologically active peanut proteins were detected in the air and seem unlikely to trigger moderate/severe allergic reactions.