Comparison of probabilistic approaches to estimate the initial bacterial levels as a start in exposure assessment: Escherichia coli O157:H7 in beef as an example

The initial contamination of food products with pathogens is an important risk factor in microbial risk assessments. This factor contains variability and uncertainty that can be calculated from various available monitoring results. When performing dedicated quantitative risk assessments, different methods can be chosen to transform the data into probability distribution functions. This paper describes methods for the quantification of data for the initial level of Escherichia coli O157:H7 in beef. The initial contamination is estimated by expert opinion, using a slaughterhouse model and directly from available monitoring data. Two fundamentally different statistical methods are described and applied to the data: an uncertainty approach and a variability approach. This study compares and discusses these methods with the aim of giving insight to the different choices that can be made in order to estimate the initial level as a starting point in exposure assessments. Copyright © 2008 Inderscience Enterprises Ltd