Food Safety and Zoonoses

Risk characterization of microbiological hazards in food

Joint FAO/WHO workshop, Copenhagen, Denmark, 24 - 28 February 2003

Background and objectives of the meeting


Risk assessment of microbiological hazards in foods (MRA) has been identified as a priority area of work by the Codex Alimentarius Commission (CAC). Following the work of the Codex Committee on Food Hygiene (CCFH), the CAC adopted Principles and Guidelines for the Conduct of Microbiological Risk Assessment (CAC/GL-30 (1999)) in 1999. Subsequently, at it 32nd session, the CCFH identified a number of areas in which it requires expert risk assessment advice.

At the international level it should also be noted that the WTO Agreement on the Application of Sanitary and Phytosanitary Measures requires members to ensure that their measures are based on an assessment of the risks, as appropriate to the circumstances, taking into account the risk assessment techniques developed by the relevant international organizations.

In response to the needs of their member countries and Codex, FAO and WHO launched a programme of work with the objective of providing expert advice on risk assessment of microbiological hazards in foods. To date, work continues on risk assessment of Listeria monocytogenes in ready-to-eat foods, Salmonella spp. in broiler chickens and eggs, Vibrio spp. in seafood and Campylobacter spp. on broiler chickens. The purpose of this work is to provide an overview of the available relevant information, as well as the risk assessments that have already been undertaken, and use these to develop risk-based scientific advice to address the needs of Codex and to develop risk assessment tools for use by member countries.

FAO and WHO are also developing guidelines documents for undertaking each of the four components of risk assessment, namely hazard identification, hazard characterization, exposure assessment and risk characterization. To date, guidelines for hazard characterization of pathogens in food and water have been finalised, and the draft guidelines for exposure assessment of pathogen in food have been prepared and are currently under review.

FAO and WHO are now planning the development of practical guidelines for risk characterization of microbiological hazards in foods. The need for such guidelines has been highlighted in the work being undertaken by FAO and WHO on risk assessment of specific pathogen-commodity combinations and it is recognized that the reliable estimate of risk is critical to the risk assessment because this is where the results of the risk assessment are presented.

The primary purpose of this workshop was to develop practical guidelines on risk characterization for microbiological hazards in food. In order to do this, the workshop compared and reviewed the approaches used in several recent risk assessments. The workshop addressed key factors in risk characterization such as:

  • How the outcome should be expressed-- is it understandable?
  • Characterization and effect of uncertainty
  • Quality assurance of the risk assessment, including validation of the estimated risk
  • Sensitivity analysis
  • Characterization of the adverse effects expected
  • Investigation of mitigation strategies

Based on currently available scientific knowledge and information, the workshop formulated practical guidelines for the conduct of risk characterization of microbiological hazards in foods.


The objective of this workshop was to develop guidelines for risk characterization of microbiological hazards in food. To this end, the workshop:

  • Reviewed the current state of development of risk characterization and elaborate guidance on undertaking risk characterization based on the experience to date.
  • Developed guidelines on the integration of the hazard characterization and exposure assessment components of the risk assessment model.
  • Elaborated guidance on the characterization of uncertainty and variability, assessing the quality of the risk assessment, and examine the purpose, utility and means of undertaking sensitivity analysis.
  • Developed guidance on the investigation of different risk management options
  • Developed guidance on defining and presenting the outputs of a risk characterization and the information needs for risk management and risk communication
  • Developed guidelines on the data needed to validate the outputs of the risk characterization