the mostuncertainaspectsof microbial risk assessment.Henceit is normally
basedon predictive microbiology modelling and simulations.A number of
relevant factorshaveto be consideredto determinethe frequency and levelof
contaminationof a pathogenic agentin food.These includethe initialcon-
tamination of the rawmaterial, the processing, packaging, distribution and
storagemethodsof the foodsand preparation steps priorto consumption. Also
consumption patterns maybe considered whichare relatedto socio-economic
and cultural backgrounds, seasonality,age,etc. The levelof microbiological
pathogens may also increaseconsiderably in case of exposure to abusive
conditions. Therefore the exposure assessment may predictthe rangeof possible
exposures depending on the effectsof processconditionssuch as hygienic
design,cleaningand disinfection,time/temperatureconditions,foodhandling
and consumptionpatterns.
Hazardcharacterisationis the evaluation of the natureof the adversehealth
effectsassociatedwiththe hazard.In the casethat dataare available, a dose±
responseassessmentshould be performed.For microbiologicalhazards it relates
to the ingestionof microorganisms or theirtoxins.The factorsto be considered
can be dividedinto threegroups:factorsrelatedto the pathogen,the foodor the
humanhost.The factors relatedto the pathogenare its virulenceand infectivity,
whichmay dependon its interactionwiththe host,and its capacity of resistance,
adaptation, replication and transmissionin specificconditions.The foodmatrix
and foodprocessconditionscan affectthe pathogenicity of a microorganism.
Highfat content mayprotect the organism from stomach acidand hence
increase the chances of survivaland consequentinfection. Factorsto consider
relatedto the host are the variation of susceptibilitydepending on age, healthor
immune status.
Riskcharacterisationis the finalstep of the risk assessment.It is the process
of estimation of the probabilityof occurrence and severityof known or potential
adversehealth effectsin a givenpopulationbasedon hazard identification,
hazardcharacterisationand exposureassessment.
Riskassessments may varyconsiderablyin depthof assessmentand structure,
depending on the purpose of the exercise.Some of themare focused on one
aspect, e.g. hazard characterisation, or do not use the Codex Alimentarius
structureand definitions.Assessments conducted by nationalor international
food safety organisations (USDA, FAO/WHO)normally contain extensive
literaturereviewsand in-depth dose±responseassessments. However, as these
risk assessments coverwholesectorswithinthe foodindustry(for example:
ready-to-eatfoods) and coverthe total productionchain, theseassessments
cannotfocuson the details of the individualfoodprocessor.Riskassessments
conducted by individualfoodprocessorsare less detailedon publichealthissues,
but focuson the prevalence and concentrationof a recognised pathogenin their
foodingredients and finishedproduct. Riskassessmentsconducted by food
equipment manufacturers focuson the hygienic design(e.g.selection of con-
structionmaterials, cleanability specifications)to minimise the risk of trans-
ferringhazardsto a foodproductduringmanufacturing (Holah,1998).
Riskassessmentin hygiene management 315