Microbiological food safety differs fundamentally from chemical
food safety, yet the risk assessment framework for microorganisms
and chemicals is the same (Ashbolt, 2004). Unlike chemical
contaminants, microbes can enter food at any point of the food
chain or during processing, while chemical residues and additives
typically enter the food chain at more or less predictable points.
Also, microbes are capable of multiplying and interacting with
the food during storage and as conditions change (Havelaar et al.,
2009). Furthermore, dose responses to foodborne pathogens are
highly variable, depending on various factors e.g. the virulence
characteristics of different pathogens or strains, number of ingested
cells, the general susceptibility of individual consumers as
well as the attributes of the food matrix. These interactions all
influence the dose–response relations (Buchanan et al., 2000).