Health risk assessment of Listeria monocytogenes in Canada

In this review, the major steps used in the formulation of a health risk assessment for Listeria monocytogenes in foods are discussed. Data is given on the numbers of human listeriosis cases reported in Canada along with the current Canadian regulatory policy on L. monocytogenes. Four major steps in the health risk assessment of this organism in foods, namely, hazard identification, hazard characterization, exposure assessment and risk characterization, were examined. For hazard characterization, since it is known that no direct human dose response data is available for L. monocytogenes, a flexible dose response model called the Weibull-Gamma model was evaluated. For the exposure assessment, pâté and soft cheese, both high-risk foods in terms of listeriosis infection, were used as prototypes in some of the models that were used. Using disappearance data for cheese and 100 g as a typical serving, the data suggested an average of 102 servings per capita, per year in Canada. As a rough approximation, for L. monocytogenes, reference ID10 and ID90 dose levels of response for both normal and high risk populations were given as 107 and 109 for normal individuals, and 105 and 107 for high-risk people. The corresponding dose response models were graphically displayed. These models exhibited a higher degree of susceptibility and less host/pathogen heterogeneity for the higher risk group. The range of doses between the ID10 and ID90 reference values corresponded roughly to levels associated with cases of listeriosis. In the risk characterization stage, dose response data was combined with some predictive.