Quantitative microbiological risk assessment using individual data on food storage and consumption (Part 1): A case study on listeriosis associated to ready-to-eat foods in France

• Listeriosis risk and cases were estimated for seven Ready-To-Eat food categories • Storing temperature greater than 7°C linked with 83% of the cases • Estimated annual cases of listeriosis were aligned with the cases reported in France • Individual-based data in QMRA opens the way for targeted food safety interventions The risk of acquiring foodborne infections such as listeriosis is influenced by individuals’ food consumption and food storage practices. So far, quantitative microbiological risk assessment (QMRA) studies have mostly treated the related variables as independent, creating potentially unrealistic high-risk conditions, such as combinations of big portion size, high frequency of consumption, high storage temperature and long storage time. Therefore, in this study, we integrated individual food consumption and food storage data collected by the French national dietary survey INCA3 with food contamination data to estimate the risk of listeriosis in France, without assuming independence of variables. The aim was to assess and compare risks for different population groups and for different food groups, to identify risk factors and characterize high-risk groups. We adapted a QMRA model previously developed for the assessment of the number of listeriosis cases associated to ready-to-eat (RTE) foods in the EU. We modified the exposure assessment to use an individual-based approach in which consumer-specific consumption data and food safety practices are used to calculate exposure. Results showed that high-risk individuals stored their food in their refrigerator for longer and at higher temperatures prior to consumption than low-risk individuals. Smoked fish and pâte were estimated to be responsible for 66% of the likely 393 annual cases for France. Improved characterization of high-risk individuals and their determinants for risk may contribute to better targeted food safety guidance. We demonstrated that considering individual-based data in QMRA opens the way for the establishment of risk-based measures that are specific for distinct individuals within the population.The advantage of this “individual-based” QMRA approach is that the observed variation between individual consumers in the four variables “frequency of consumption”, “portion size”, “storage time” and “storage temperature” is taken into account, and that it includes their interdependency for each individual consumer.