Risk assessment of Listeria monocytogenes in fish products: some general principles, mechanism of infection and the use of performance standards to control human exposure.

Risk assessment is increasingly used as a scientific process to assess the potential for adverse health effects to occur and as a basis for management of unacceptable risks. For each risk assessment activity, the purpose of the assessment should be clearly stated. For Listeria monocytogenes, the purpose of risk assessment may be providing information on the relative contribution of listeriosis to infectious diseases. For control purposes, the emphasis may be put on factors contributing to the risk of occurrence in a food or to inform risk managers that they should be setting food safety objectives. For an adequate risk assessment of L. monocytogenes, sound scientific data are necessary. This especially applies both to exposure assessment and hazard characterisation. Surveillance data indicates that cold storage to prolongs product shelf-life has opened an ecological window for the growth of L. monocytogenes. Assessment of dose-response relationship is often regarded as a key element in risk characterisation. Due to the large variability of the current assessed dose-response data, their contribution to assessing risks is low. The use of epidemiological data on incidence rate, types of food involved in listeriosis, etc. may be good alternatives. The use of performance standards or criteria, such as inactivation by heat or by fermentation, combined with processes that prevent outgrowth of the organism should be reconsidered. Presently, performance standards can simply be assessed since mathematical tools for their calculations are becoming increasingly available.