Concentrations of undeclared allergens in food products can reach levels that are relevant for public health.

Food products can become contaminated with food allergens due to cross-contact. Precautionary 'may contain' labelling may alert to the possible presence of an allergen, but guidance for such labelling is lacking. As a result, allergy information on the packaging may not be reliable and allergic consumers might be at risk of allergic reactions after consuming unlabelled, but indeed contaminated, products. Recently, a cow's milk protein allergic patient experienced a severe allergic reaction to a dark chocolate product containing undeclared milk proteins. This case induced the authors to investigate to what extent allergen concentrations of unlabelled products reach levels that are of public health relevance. The concentrations of milk proteins in the complaint sample and a collection of products of other batches and brands purchased from different stores were analysed. Together with appropriate threshold and food consumption data, the risks of allergic reactions and the severity of these reactions within the adult milk-allergic population were determined using probabilistic risk assessment techniques. The results show that milk protein concentrations in unlabelled products reach levels that may elicit allergic reactions in up to 68% of the adult allergic consumers. Therefore, concentrations of allergens in unlabelled products could reach levels that are of public health relevance. Application of probabilistic risk assessment can be an aid in revealing the public health consequences of undeclared allergens in food, in risk management decision-making and developing guidance in terms of risk-based concentration limits for precautionary labelling.