The process for developing the FDA/FSIS risk assessment included a period for public comment on a January 2001 draft of the L. monocytogenes risk assessment (FDA and FSIS, 2003b). The final risk assessment summarized the changes made to the draft in response to the comments received. Many of those changes reflected decreased uncertainties as a result of the feedback received. They included changes to the food categories to better incorporate characteristics that contribute to the support of growth of L. monocytogenes (for example, moisture content and pH), updated data on contamination, growth rates of L. monocytogenes in different foods and for different storage durations, the frequency and prevalence of L. monocytogenes on different foods, consumer habits, and modifications to the model used.
Decisions in the Face of Uncertainty: Lessons Learned
The assessment of L. monocytogenes and FDA’s use of that assessment highlight how analyses of health risks that account for uncertainties—such as those for different food types, different storage conditions, and different susceptible populations—can provide decision makers with information to help design policies that target mitigation strategies to the greatest risks, either for specific foods with a higher likelihood of being associated with human illness, or for populations that are more susceptible to illness. The detailed and specific risk characterization allowed FDA and FSIS to develop specific guidance for different foods and to develop outreach strategies to protect the populations at highest risk from consumption of foods contaminated with L. monocytogenes.3 In other words, the assessment and how it was used in FDA’s decision highlights the importance of analyzing the heterogeneity in an assessment and demonstrates how—when uncertainty about that heterogeneity is reduced—an agency can better tailor risk-mitigation options.
In light of the complexity of the risk assessment, the agency also evaluated methods for grouping the results for communication purposes (FDA and FSIS, 2003b). The assessment concluded, “One approach that appears to be very useful for risk management/communication purposes is the evaluation of the relative risk ranking results using cluster analysis”
3 A recent outbreak of L. monoctyogenes in cantaloupes, however, shows that even lower-risk foods are not immune to contamination. See CDC (2011a) for a description of the outbreak. FDA investigated that outbreak, identified a number of factors that contributed to the outbreak (FDA, 2011c), and highlighted the need for all processors to employ good agricultural and management practices (FDA, 2011c), as are provided in FDA and USDA guidance to industry (FDA, 2008c).