A primer on risk assessment modelling: focus on seafood products

Aamir M. Fazil
Lead Scientist, Health Risk Modelling
Laboratory for Foodborne Zoonoses
Public Health Agency of Canada
Ottawa, Canada

Rome, © FAO 2005


The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

ISBN 92-5-105417-7

All rights reserved. Reproduction and dissemination of material in this information product for educational or other non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holders.
Applications for such permission should be addressed to:
Publishing Management Service
Information Division
Viale delle Terme di Caracalla, 00100 Rome, Italy
or by e-mail to:

Preparation of this document

This Technical Paper is written as an introduction to the concepts of microbial risk assessment in general, but with a seafood focus and a greater emphasis on the quantitative approach. Every attempt has been made to write in an illustrative manner and wherever possible, examples have been used to highlight the concepts and applications that are introduced. It provides an introduction to the different types of models and concepts that can appear in a risk assessment, and how they contribute to the decision-making process.

The document is written at a level to provide utility for different groups of people. It can serve as a guide for individuals in the field starting out in risk assessment, who may be in search of an illustrative and applied text. It is also suitable for risk managers who are not involved directly in creating risk assessments, but who need to have an awareness and appreciation of the details and potential applications of microbial risk assessment.

The content and layout of the document is a result of the many presentations, workshops and training courses that the author and his colleagues have conducted to a wide variety of audiences, and responds to the need for a basic and very illustrative text to accompany these sessions.


The author wishes to acknowledge many of his colleagues who, through both formal and informal discussions, have shaped much of the content reflected in this publication. Special thanks go to Hector Lupín of the Food and Agriculture Organization of the United Nations, Fisheries Department, who felt it was important to have this document prepared for the seafood industry, had confidence that I should prepare it, and made sure the work was completed. In addition, thanks to the following people who helped either directly or indirectly: Anna Lammerding, Greg Paoli, Judy Greig, Janet Harris, Charles Haas and Tom Ross.

The author’s wife, Lisa-Marie, is also acknowledged for her support and encouragement, and for making sure that after the typing stopped, there was no shortage of things to get done around the house.


The risk of foodborne disease is a combination of the likelihood of exposure to the pathogen, the likelihood of infection or intoxication resulting in illness, and the severity of the illness. In a system as complex as the production and consumption of food, many factors affect both the likelihood and severity. To effectively manage food safety, a systematic means of examining these factors is necessary. There has been an increasing appreciation that by providing a framework that contributes towards the understanding of systems, risk assessment is an ideal tool for this purpose. The increased understanding translates to a better informed selection of risk mitigation or reduction strategies and an ability to identify knowledge gaps, which can subsequently direct research.

International agencies and all levels of government are increasingly relying on, or at least recognizing the need to rely on, risk assessments for public health protection, international trade, decision-making and cost-effective resource allocation.

Fazil, A.M.
A primer on risk assessment modelling: focus on seafood products.
FAO Fisheries Technical Paper. No. 462. Rome, FAO. 2005. 56p.

Hyperlinks to non-FAO Internet sites do not imply any official endorsement of or responsibility for the opinions, ideas, data or products presented at these locations, or guarantee the validity of the information provided. The sole purpose of links to non-FAO sites is to indicate further information available on related topics.

This electronic document has been scanned using optical character recognition (OCR) software. FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.


Preparation of this document



1.    Introduction

1.1    Risk

1.2    Risk analysis

1.2.1    Risk management

1.2.2    Risk assessment    Hazard identification    Exposure assessment    Hazard characterization and dose-response analysis    Risk characterization

1.2.3    Risk communication

1.3    Modelling and the concept of a “harvest-to-consumption” model

2.    Mathematical models

2.1    Types of models

2.1.1    Static and dynamic simulation models

2.1.2    Continuous and discrete simulation models

2.1.3    Deterministic and stochastic simulation models

2.1.4    Monte-Carlo analysis

2.1.5    Uncertainty and variability

3.    Harvest-to-consumption models

3.1    Pre-harvest models

3.1.1    Example (pre-harvest module)

3.2    Harvest models

3.3    Handling and processing models

3.4    Storage and distribution models

3.4.1    Example of growth modelling

3.5    Preparation and consumption

3.5.1    Preparation    Example preparation model (cooking)

3.5.2    Consumption

4.    Dose-response

4.1    Example dose-response model (Vibrio cholerae)

5.    Risk characterization

5.1    Presentation of results

5.2    Summary

6.    Conclusion

7.    References