Risk-Ranking Models for Foods
Among FDA-regulated products, foods are probably the category that has been the focus of more risk-assessment and ranking studies than any other products. Several government agencies and research groups have developed risk-ranking approaches and models, and the National Research Council (NRC) and the Institute of Medicine (IOM) have published several reports addressing the need for ensuring the safety of foods (IOM/NRC 1998, 2003, 2010). In the latest report, different risk-ranking models developed by researchers and regulators in different countries were contrasted. The “degree of complexity, level of quantification, and approach to model construction” differed among the models (IOM/NRC 2010). However, some of the common criteria identified were “(1) burden of illness…(2) illness severity, (3) population susceptibility, (4) likelihood of contamination, (5) potential for agent amplification, and (6) breadth of exposure” (IOM/NRC 2010, p. 87). The risk-characterization framework proposed here considers all those factors although some are not called out explicitly: (3) and (6) are included in exposed population; (1) and (2) are covered and expanded under mortality and adverse health effects; (4) and (5) must be considered to develop estimates of the number of deaths and other adverse health effects and thus are implicitly included in this framework. However, like the risk-ranking models described in the recent IOM/NRC report, the risk-characterization framework proposed here was designed for a specific purpose, which was to characterize the public-health consequences of various decisions at FDA among all its programs, and therefore does not include program-specific attributes that would not be universally applicable, such as the probability of contamination and amplification in the food supply.
The decision context considered in this case study was one of allocating food-safety inspection resources; that is, if additional inspection resources were available, how should they be allocated among the various food categories to maximize public-health protection? That general decision problem is too large to be undertaken as a case study, so a much simplified decision context and evaluation were selected. Rather than considering all the different options for what types of food could be inspected, this case study considers only three specific food categories: leafy greens, shrimp, and canned foods. The categories were chosen to highlight products that are inherently different with respect to level of processing, origin, and potential risks. Furthermore, rather than identifying all the possible allocations of inspection resources that could potentially be compared, this case focuses only on characterizing the public-health consequences associated with each food category assuming the current regulatory and inspection regime. The results of this evaluation could be used directly for ranking or