An international Delphi panel convened by the World Allergy Organization (WAO) ACT-UP! initiative reached consensus on 33 of 35 statements addressing precautionary allergen labeling, recommending action levels for "may contain" warnings rely on population-adjusted eliciting dose (ED05) reference doses rather than fixed allergen concentrations.¹ ED05 denotes the amount of allergen estimated to trigger an objective reaction in no more than 5% of the allergic population.
Precautionary allergen labeling remains unregulated and voluntary in most countries, a gap the WAO first flagged more than a decade ago, and food businesses have responded with defensive over-labelling even when unintended allergen presence is unlikely.¹ The FAO/WHO Expert Consultation, convened through the Codex Committee on Food Labelling, previously proposed reference-dose thresholds for priority allergens:2
- 2 mg total protein: peanut, egg, milk, sesame
- 3 mg: hazelnut
- 5 mg: wheat, fish
- 10 mg: soy, lupin
- 1 mg: other tree nuts, celery, mustard
- 200 mg: crustacean shellfish
However, reference-dose thresholds offer limited opportunity for clinician input. The ACT-UP! working group launched this 3-round e-Delphi involving 35 experts across 21 countries to fill the resulting gap.
"[Precautionary allergen labelling] should only be applied when a legally regulated risk assessment indicates the likelihood of unintended allergen presence, which can pose a risk to allergic individuals," wrote author Antonio Bognanni, MD, PhD, from McMaster University, and colleagues.¹
Delphi Methodology and Consensus on Reference-Dose Thresholds
The panel, 60% clinicians alongside methodologists, food technologists, regulators, dietitians, and patient advocates, rated 35 statements across 7 domains on a 5-point Likert scale over 3 rounds, with a 100% response rate at every round. Consensus was predefined as ≥ 70% agreement or disagreement, excluding neutral responses, with stability requiring < 10% variation in mean scores between rounds. Statements reaching ≥ 90% agreement with no change in status across 2 rounds were dropped from further voting to limit survey fatigue.
Consensus climbed from 86.1% of statements (31 of 35) in round 1 to 91.4% (32 of 35) and 94.3% (33 of 35) in rounds 2 and 3, respectively. The panel agreed precautionary allergen labeling should apply only when unintended allergen presence exceeds an action level set through a mandatory, preferably quantitative, risk assessment. Action levels should be based on reference doses of total allergenic protein for a typical portion, rather than a fixed concentration such as 10 ppm, and specifically on ED05 values rather than the more conservative ED01.This would protect against the risk of precautionary allergen labeling overuse.
Precautionary Allergen Labelling Communication, Free-From Labels, and Liability Findings
Fixed-concentration thresholds drew the most disagreement: panelists rejected a 5 ppm cutoff, while 10 ppm never reached consensus. On wording, "may contain X" was the consistently preferred phrasing, rising from 52% support in round 1 to 71% by round 3, ahead of "may contain traces of X" and "not suitable for people with an allergy to X."
Precautionary allergen labelling communication posted the lowest final domain consensus: 70% of the panel agreed consumers need information about residual risk from unintended allergen presence below the reference dose, but a proposed 2-tier precautionary allergen labelling system failed to reach consensus across rounds.
On free-from claims, 97% of panelists agreed labels declaring an allergen absent should mean no detectable presence, including via unintended allergen presence. A consensus reached 81% for excluding precautionary allergen labeling on vegan-labeled foods for milk, egg, or other animal-derived allergens, and 80% favored redefining "gluten-free" to mean an absence of gluten rather than the current 20-ppm threshold. The liability domain reached full consensus: food business operators demonstrating regulatory compliance should not be held liable for reactions caused by unintended allergen presence.¹
The recommendations are intended to reinforce the FAO/WHO Expert Consultation, currently under review by the Codex Committee on Food Labelling, by providing clinician- and interest-holder-derived input largely absent from the regulatory process to date.¹ The authors identify harmonized international food-consumption datasets, multilingual validation of precautionary allergen labelling wording, and continued monitoring of allergic reactions occurring below current reference-dose thresholds as future research priorities.
References
Bognanni A, Sousa-Pinto B, Morais-Almeida M, et al. World Allergy Organization (WAO) Consensus on the use and practice of precautionary allergen labelling: The international ACT-UP! e-Delphi. World Allergy Organ J. 2026;19(8):101436. doi:10.1016/j.waojou.2026.101436
Turner PJ, Bognanni A, Arasi S, et al. Time to ACT-UP: update on precautionary allergen labelling (PAL). World Allergy Organ J. 2024;17(10):100972. doi:10.1016/j.waojou.2024.100972
