Predicting risk of reaction to cross-contact allergens

An incident in which a patient with allergy to cow's milk experienced a severe allergic reaction to a dark chocolate product that did not bear a milk allergen declaration prompted scientists in the Netherlands to investigate the extent to which allergen concentrations in unlabelled products reach levels that may cause public health problems.

The researchers analysed the concentrations of milk proteins in a variety of products. In total, twelve packages of nine different brands of dark chocolate sprinkles from different regional stores were collected and analysed, along with the complaint sample. Three of the products were labelled for the presence of milk proteins and ten were not.

The risks of allergic reactions and the severity of these reactions within the adult milk-allergic population were determined using probabilistic risk assessment techniques. This is a risk assessment methodology that calculates the magnitude of the potential health risk posed by defined concentrations of food allergens based on modelling of food consumption, allergen concentration and threshold distributions. These were combined to determine the proportion of the population that may be at risk of an allergic reaction, plus the potential severity of this reaction. The results of this risk assessment technique are expressed as the percentages of the milk protein-allergic adult population expected to experience an allergic reaction due to unlabelled products that contain allergens due to cross contact.

The results of the risk assessment on the unlabelled dark chocolate products showed that the concentrations of milk protein were at levels that may elicit allergic reactions in up to 68% of adult allergic consumers.

In most countries there is no guidance on the use of 'may contain' labelling. Application of this type of probabilistic risk assessment could be used to assess the public health consequences of undeclared allergens in food, aid in risk management decision-making and in developing guidance in terms of risk-based concentration limits for precautionary labelling.

Reference: Spanjersberg et al. 2010. Food Additives & Contaminants, Vol27 (2). pp 169-174. Doi:10.1080/19440040903317513

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