Riskassessmentconsists of the evaluation of the probabilityof occurrenceof
the hazard and the adverseeffectof the hazard.Suchan assessmentcan contain
valuable informationfor the implementationof a managementprogramme, such
as HACCP, which is the procedure thatultimately willset the means to
eliminate,control or reduce the hazardto acceptable levels. Riskassessment
assists during the implementation of the HACCP to identify the hazards
associatedwitha product. In addition risk assessments collect informationabout
the influenceof processor storageconditionsthat mayaffectthe viability of
foodborne pathogens.Thiswill helpHACCP to identifythe steps in the food
production that are critical to foodsafetyand at whichcontrolactionswould
produce a great reductionin risk. Hence, it is of potential use for CCP
identification. Finally risk assessmentsprovide a valuable scientific foundation
to determinethe critical limits relatedwitheachCCP.
20.3 Examplesof risk assessments
20.3. 1 Listeriamonocytogenesin ready-to-eatfoods
An assessmentof the risk to publichealthfromListeriamonocytogenesin
selectedready-to-eatfoodswas conducted by the UnitedStates Department of
Agriculture(USDA,2003a,2003b).Thisrisk assessmentestimated the potential
level of exposure of threeage-based groupstoL. monocytogenesfrom23 food
categoriesand relatedthis to publichealthconsequences.The threeage-based
groupswereperinatals, elderly and the intermediate-age group.Predictions from
the risk assessmentweregivenin two forms:the estimatedrate of fatalinfection
on an individualservingbasisand the estimatednumberof fatalinfections per
yearin the US (per annumrisk'). For eachfoodcategory and eachage-based groupthe per annumrisk is derivedfromthe per servingrisk by multiplyingthe latter by the yearlynumberof servingsof the foodcategoryby that specific age- basedgroup. Therisk assessment wasbasedon the fourstepsaccording to the CAC (1999). In thehazardidentificationstep, the health effectsassociated withL. monocytogeneswereidentified.Themainpartof the studyis theexposure assessmentwhichestimateshow oftenconsumers eat foodcontaminated withL. monocytogenesand estimates the number of bacterialikelyto be in that food. The contaminationdata usedwerefrompublished and unpublished studiesthat mainly concernedfoodsamples collected at retail.Mathematical modelswere thenusedto calculate the changes in contaminationlevelsduringrefrigerated storageand reheatingin the home,thus obtainingthe contaminationlevel at the moment of consumption.Thesemodelsconsidered factors suchas refrigerator temperaturesduringstorage, the specificsof the variousfoodcategories, and the estimatedlengthof timethat foodis stored.Finally, the number of servings, necessaryto calculate theperannum risk', was estimatedfor eachfood
categoryand for eachage-based groupusing data fromtwo largenationwide US
foodconsumption surveysconducted in the 1990s.
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