Quantitative microbial risk assessment: methods and quality assurance

Quantitative microbial risk assessment (QMRA) is used to estimate the risk level of pathogens along the food chain and to support management decisions for the reduction of food safety risks. The degree of credibility that can be attached to risk assessment results depends largely on the quality and quantity of the data, the model structure and the assumptions made. Quality Assurance (QA) in QMRA is defined as the structure that ensures that all the steps in the risk evaluation process are scientifically based so that the policy questions being posed can be answered. Whereas sensitivity analysis and scenario analysis are generally applied in QMRA, formal methods for the evaluation of data quality, the critical evaluation of assumptions, structured expert elicitation, the checklist approach and peer review are rarely used in QMRA, even though they would improve the transparency of the risk analysis process. An overview of QA methods for QMRA is presented. The degree of implementation of these methods should be proportionate to the stakes of the risk management questions and should be discussed in consultation between the risk assessors and the risk managers.