This book concerns itself with the quantification of risk, the modeling of identified risks and how to make decisions from those models. Quantitative risk analysis (QRA) using Monte Carlo simulation offers a powerful and precise method for dealing with the uncertainty and variability of a problem. By providing the building blocks the author guides the reader through the necessary steps to produce an accurate risk analysis model and offers general and specific techniques to cope with most modeling problems. A wide range of solved problems is used to illustrate these techniques and how they can be used together to solve otherwise complex problems.

This volume takes a comprehensive and expansive approach to the subject of microbial risk assessment, including information for beginning risk assessors who need to take the next step in their education, as well as for university researchers, graduate students, industry analysts, and government risk managers.

Regulatory agencies often perform microbial risk assessments to evaluate the change in the number of human illnesses as the result of a new policy that reduces the level of contamination in the food supply. This study proposes a framework for conducting microbial food-safety risk assessments; this framework can be used to quantitatively assess the annual effects of national regulatory policies. Advantages of the framework are that estimates of human illnesses are consistent with national disease surveillance data (which are usually summarized on an annual basis) and some of the modeling steps that occur between production and consumption can be collapsed or eliminated. The framework leads to probabilistic models that include uncertainty and variability in critical input parameters; these models can be solved using a number of different Bayesian methods. 

This article illustrates that characterizations of the risks associated with foodborne pathogens are dependent on the availability of information on the population's exposure to the biological agents. However, by itself, exposure data are insufficient to assess the public health impact of pathogenic microorganisms. This requires the availability of effective dose-response models. Successful development of models that describe dose-response relations for enteric pathogens is dependent on a sound understanding of the mechanisms of pathogenicity associated with individual pathogens. This includes knowledge of how the various pathogen, host, and food matrix factors influence pathogenicity. This paper explains that advances in microbial food safety risk assessment will likely require the development of mechanistic models that effectively consider the range of factors that influence the frequency and severity of foodborne infections in a population.

This paper describes a system for the microbiological quantitative risk assessment for food products and their production processes. The system applies a stepwise risk assessment, allowing the main problems to be addressed before focusing on less important problems. The system for quantitative risk assessment has been implemented as a decision supporting expert system called SIEFE: Stepwise and Interactive Evaluation of Food safety by an Expert System. SIEFE performs bacterial risk assessments in a structured manner, using various information sources. Because all steps are transparent, every step can easily be scrutinized. In this study the effectiveness of SIEFE is shown for a cheese spread. This example shows that SIEFE provides quantitative insights into production processes and their risk-determining factors to both risk assessors and decision makers, and highlights critical gaps in knowledge.

This article presents a systematic approach to microbial risk assessment that employs data analysis for developing parsimonious models and accounts formally for the variability and uncertainty of model inputs using analysis of variance and Monte Carlo simulation. The purpose of the paper is to raise and examine issues in conducting microbial risk assessments. The enteric pathogen Escherichia coli O157:H7 was selected as an example for this study due to its significance to public health.

This article illustrates that quantitative risk assessment (QRA) is rapidly accumulating recognition as the most practical method for assessing the risks associated with microbial contamination of foodstuffs. This paper looks at a number of modeling techniques that can help produce more realistic and accurate Monte Carlo simulation models. This article also explains the use and limitations of several distributions important to microbial risk assessment.

This article describes the increased desire for quantitative data on the microbial risks associated with different classes of foods and its potential use within microbial risk assessement in international trade.

This article explains that as the risk assessment paradigm is increasing applied and as decision-making criteria for risk management become established, more emphasis will be placed on predictive microbiology as a means of generating exposure data and establishing critical limits for Hazard Analysis Critical Control Point (HACCP) plans. In this respect, developing international guidelines for risk management arguably presents the greatest challenge in establishing and maintaining quantitative Sanitary and Phytosanitary (SP) measures for food in international trade, and for judging their equivalence.

This article emphasizes that risk assessment provides the critical scientific basis to better protect public health and gain the greatest impact towards safer food by providing the tools to effectively address important risk management decisions.

This article also mentions that quantitative data is critical for risk assessment to realize its full value. Predictive modeling should help to improve estimates and thereby allow quantitation of food safety risks. Predictive modeling will also find application for assessing prevention strategies in risk management.

This article presents a framework for a Monte Carlo model of a generic food system to illustrate one potential approach to quantitative risk assessment for microbial food safety.

This Monte Carlo model framework links together food ingredients, batch processing, cross contamination, microbial growth, cooking, recontamination, consumption, human exposure to pathogens, the dose-response relationship, and the biologic and economic impact components of such risks. This framework requires refinement with appropriate distributions and mathematical relationships before it can be applied to a specific pathogen-food-consumer situation.

The Risk Assessment Subcommittee of the National Advisory Committee on Microbiological Criteria in Foods has prepared a generic document on the principles of risk assessment as applied to biological agents that can cause human foodborne disease. Typical biological agents include bacteria, viruses, fungi, helminths, protozoa, algae, parasites, and the toxic products that these agents may produce.

Basic principles elaborated to characterize food pathogen risks include the four broadly accepted components of risk assessment. The role of surveillance and investigational activities to link biological agents and their food sources to consumer illness is described as is the role of predictive modeling for food pathogens.

This article illustrates the role of Monte Carlo simulations in quantitative microbial risk assessments. It explains that Monte Carlo simulation can provide insights into complex processes that are invaluable, and otherwise unavailable, to those charged with the task of risk management.

This paper describes specifically how such goals as research prioritization, risk-based characterization of control points, and risk-based comparison of intervention strategies can be objectively achieved using Monte Carlo simulation.

This article uses as an example a farm-to-fork model of the fate of Escherichia coli O157:H7 in ground beef hamburgers.

This article discusses the growth and inactivation models that can be used in a stepwise procedure for quantitative risk assessment. The proposed stepwise procedure provides a structured method of risk assessment and prevents the researcher from getting caught in too much complexity. This simplicity is necessary because of the complex nature of food safety. The principal aspects are highlighted during the procedure and many factors can be omitted since their quantitative effect is negligible.

The revised ILSI framework for conducting microbial risk assessments (MRA) including the companion glossary of terms for MRA (Section 4) and the table of synonymous terms in risk assessment (Section 5) are useful elements to consider in the continuing development and evolution of MRA.

This report also includes a summary of the water- and foodborne pathogen risk assessment workshop held on May 11-12, 1999.

This article presents and discusses a broad review of probabilistic risk assessment (PRA) literature published since 2000. 

Whether and to what extent contaminated sites harm ecologic and human health are topics of considerable interest, but also considerable uncertainty. Several federal and state agencies have approved the use of some or many aspects of PRA, but its site-specific application has often been limited to high-profile sites and large projects. Nonetheless, newly developed software tools, and recent federal and state guidance documents formalizing PRA procedures, now make PRA a readily available method of analysis for even small-scale projects. 

The aim of microbiological risk assessment is to facilitate decision making at various levels of food safety management. Food suppliers must make the decision for their customers or consumers. Hazard Analysis and Critical Control Point (HACCP) is the system of choice to produce safe food. During the elaboration of an HACCP plan, many decisions must be made, and risk assessment may be a useful tool in this process. Governments should use risk assessment to select risk management measures for both the internal market and the export market because the GATT/SPS agreement stipulates that standards used for food in international trade should be established on scientific principles and risk assessment. This article provides a practical approach to the risk assessment of Listeria monocytogenes as an example.

Risk estimates for food-borne infection will usually depend heavily on numbers of microorganisms present on the food at the time of consumption. As these data are seldom available directly, attention has turned to predictive microbiology as a means of inferring exposure at consumption.

Codex guidelines recommend that microbiological risk assessment should explicitly consider the dynamics of microbiological growth, survival, and death in foods. This article describes predictive models and resources for modeling microbial growth in foods, and their utility and limitations in food safety risk assessment.

Quantitative estimates of absolute microbial risk within narrow confidence intervals do not yet appear to be possible. Nevertheless, the expression of microbial ecology knowledge in “predictive microbiology” models does allow decision support using the tools of risk assessment.

To describe the transmission dynamics of a pathogen over a food pathway in quantitative microbiological risk assessment (QMRA), several types of processes need to be modelled. Next to microbial processes like bacterial growth and inactivation, four food handling processes can be identified. Among these are partitioning and mixing of the food product.  

Some examples show the effect of more realistic modelling on the prevalence and the probability distribution of the number of pathogens per unit of food product. In general, cell clustering will result in lower prevalences, but higher levels of contamination in contaminated food units. With the methods presented, these effects can be quantified. Difficulties in estimating the model parameters and the impact of implementation of the proposed methods on risk estimates in QMRA are discussed.

This article presents a poultry-processing model for a quantitative microbiological risk assessment (QMRA) of Campylobacter, which can also be applied to other QMRAs involving poultry processing.

The same basic model is applied in each consecutive stage of industrial processing. It describes the effects of inactivation and removal of the bacteria, and the dynamics of cross-contamination in terms of the transfer of Campylobacter from the intestines to the carcass surface and the environment, from the carcasses to the environment, and from the environment to the carcasses.

The authors emphasized that good knowledge of the variability of bacterial loads on poultry entering the process is important. Some additional complications in applying microbiological data obtained in processing plants are discussed.

The need and desirability of being able to perform quantitative microbial risk assessments for food processing and preparation operations has been discussed extensively for the past several years. However, there has been little application of this approach in large part due to the need to account for the changes in bacterial populations as a result of food environments and processing.

The use of predictive food microbiology models has the potential for overcoming these limitations. Through integration of predictive modeling with risk assessment, it is possible to estimate how changes in unit operations are likely to affect the overall safety of a food.

This article provides hypothetical examples of how these techniques could be applied to both single-step and multiple-step food processing and preparation operations are provided.

HACCP plan adoption has greatly enhanced the food industry's ability to systematically design programs to ensure the microbiological safety of foods. Yet, this widening acceptance of the HACCP system has revealed several areas where its application is limited due to reliance on qualitative consideration of hazards and their control. In particular, HACCP planning is limited both conceptually and practically by its inability to quantify the potential combined influence of multiple control-point deviations and to relate the successful operation of a HACCP system to a measurable public-health impact. Recent advances in quantitative microbiological risk assessment appear to offer a means of overcoming these limitations. The integration of HACCP plans with the development of dynamic risk-assessment models offers a means for considering the entire farm-to-table continuum and for relating food-manufacturing operations to public health goals. Such capabilities may be critical to establishing equivalence among HACCP systems.

In quantitative risk assessments a large variety of complexities can be found, from simple and deterministic to very extensive and stochastic. This publication advocates that both simple and complex approaches have their value and should be done in parallel.

The simple analysis gives much insight and can help to detect main factors and potential errors in the complex analysis. Extensive analysis with increased complexity suggests better precision but might not increase the accuracy, due to the uncertainty in the additional parameters. However, complex analysis supplies more confidence in certain phenomena and might also increase insight.

This article includes two examples. The first example illustrates effectiveness of sampling plans and the second one is a model comparison of dose–response relations. 

In this article, the modular process risk model (MPRM) is briefly introduced as a QMRA modelling framework. This framework can be used to model the transmission of pathogens through any food pathway, by assigning one of six basic processes (modules) to each of the processing steps. Bacterial growth is one of these basic processes. It is suggested that a new type of predictive models needs to be developed that incorporates modelling of variability and uncertainty in growth.

In quantitative microbiological risk assessment (QMRA), the consumer phase model (CPM) describes the part of the food chain between purchase of the food product at retail and exposure. Construction of a CPM is complicated by the large variation in consumer food handling practices and a limited availability of data. Therefore, several subjective (simplifying) assumptions have to be made when a CPM is constructed, but with a single CPM their impact on the QMRA results is unclear. The researchers therefore compared the performance of eight published CPMs for Campylobacter in broiler meat in an example of a QMRA, where all the CPMs were analyzed using one single input distribution of concentrations at retail, and the same dose-response relationship. 

This IPCS project was created to update the principles and methods for the risk assessment of chemicals in food. The individual chapters as well as all other relevant parts of this document are published here separately.

This website introduces a framework for an integrated, holistic approach to risk assessment that addresses real life situations of multichemical, multimedia, multiroute, and multispecies exposures.

Historically, chemical risk assessment methodologies have generally developed independently. Regulatory agencies often use a chemical-by-chemical approach, focusing on a single media, a single source, and a single toxic endpoint. Many international and national organizations have expressed a need for an integrated, holistic approach to risk assessment that addresses real life situations of multichemical, multimedia, multiroute, and multispecies exposures.

In response to this need, the International Programme on Chemical Safety (IPCS) convened a group of international scientific experts to develop approaches for a framework for integrated risk assessment.

This website includes the report prepared for the WHO/UNEP/ILO International Program on Chemical Safety and a case study.

This website provides a consolidated list of published Environmental Health Criteria and those in development together with published documents from the IPCS Harmonization project and those relating to new and emerging issues. This list is organized alphabetically by topic.

The related publication of this joint IPCS/OECD project includes a glossary of environmental health terms used in chemical hazard/risk assessment that has been internationally harmonized.

This IPCS Risk Assessment Terminology document includes risk assessment and expossure assessment terms that are published in a two-part document which may facilitate the mutual use and acceptance of chemical assessments between countries, thus saving resources for both governments and industry.

Part 1: IPCS/OECD Key Generic Terms used in Chemical Hazard/Risk Assessment, presents generic terms used in the process of determining hazard and risk.

Part 2: IPCS Glossary of Key Exposure Assessment Terminology, includes technical terms used in human health and environmental hazard and risk assessment.

The harmonized terms may also be used as a basis for preparing other publications primarily aimed at public information and health education.

The overall mission of this project is to ensure better chemical risk assessment and hence management practices that promote the protection of human health and the environment within the framework of sustainable development.

This article evaluates the proposed definition of Food Safety Objectives (FSOs) and their implementation from the perspective of Quantitative Microbiological Risk Assessment (QMRA). The relationship between QMRA and FSOs is illustrated by a model for the public health risk of Shiga-toxin producing Escherichia coli in steak tartare. The authors concluded that the proposed definition of FSOs needs to be modified to properly account for variability in and uncertainty about the contamination of food with pathogenic microorganisms and emphasize that both prevalence and concentration of pathogens must be considered. For this purpose, the authors proposed the P-D equivalence curve, a simple graphical tool to separate "tolerable" from "non-tolerable" combinations of prevalence and concentration (dose).

A survey was sent to scientists in the food industry to determine their perspective on the role of predictive microbiology in conducting microbial risk assessments. In this paper, responses to that survey are presented, as well as examples of the potential risk of foodborne illness from a cooked meat product contaminated with Staphylococcus aureus and hamburger contaminated with Salmonella.

The present study considers how the Key Events Dose-Response Framework (KEDRF) might be applied to pathogenic microorganisms, using fetal listeriosis resulting from maternal ingestion of food contaminated with L. monocytogenes as an initial example.

The aim of this study was to describe the approach used in conducting a fit-for-purpose risk assessment of microbiological human pathogens associated with fresh fruit and the risk management recommendations made. A qualitative risk assessment for microbiological hazards in fresh fruit was carried out based on the Codex Alimentarius (Codex) framework, modified to consider multiple hazards and all fresh (whole) fruits.

This page provides various resources for risk assessment and safety assessment information through the U.S. Food and Drug Administration. Topic areas include; basic information, allergens, specific bacteria, food additives, food defense, and chemical hazards.

This paper presents a discussion of the first two steps of food safety risk assessment: hazard identification and exposure assessment, and considerations for different approaches that can be used to analyze the relevant information.

In 2007, members of the Interagency Risk Assessment Consortium, the U.S. Health and Human Services Office of the Assistant Secretary for Planning and Evaluation, the Institute of Medicine’s Food Forum, and the International Life Sciences Institute planned the Nutritional Risk Assessment Workshop. This workshop, which was envisioned as one in a series, focused on opening a dialogue to explore the unique questions and challenges faced by nutritionists and the potential use of risk assessment methodologies to answer them. This workshop summary demonstrates the activities conducted during the meeting.

Here, the author focuses on bias in prevalence estimates attributable to the use of imperfect tests and describes the techniques available to risk analysts for adjustment of test based estimates to true prevalence estimates. Also, the article describes methods for evaluation of test accuracy in the absence of a gold standard reference test that provide a useful alternative approach to traditional methods. Finally, the author demonstrates the utility of Bayesian methods and Markov chain Monte Carlo simulation for prevalence inferences for rare events and clustered data obtained from single and multiple populations and for estimation of the accuracy of correlated diagnostic tests.

The purpose of the guidelines is to provide a practical framework and approach for undertaking exposure assessment of microbiological hazards in foods in the context of a risk assessment or as a stand-alone process.

The guidelines are aimed at those with a scientific or technical background working in the public or private sector and who want or need to learn more about and undertake exposure assessment. However, it is also the intention of the document to assist risk managers and decision-makers to better understand the process of exposure assessment and help them to plan for and to provide the resources required to undertake such an assessment.

This document may also be found here.

The Director of Center for Food Safety and Security Systems (CFS3), Dr. Robert Buchanan, has been collecting and indexing relevant articles in the area of microbial food safety for the last 25 years. He is making his personal efforts available to the public through FoodRisk.org. The databases are available in Microsoft Access and are organized in 12 files according to the main subject matter. Once downloaded, the databases can be searched, queried, and used to develop reports using the various capability available within Microsoft Access. The database topics include acid resistance, different biological pathogens, Hazard analysis of critical control points (HACCP), predictive microbiology, produce, risk assessment, and seafood.

The Joint FAO/WHO Expert Committee on Food Additives (JECFA) is an international expert scientific committee that is administered jointly by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO). It has been meeting since 1956, initially to evaluate the safety of food additives. Its work now also includes the evaluation of contaminants, naturally occurring toxicants and residues of veterinary drugs in food.

JECFA normally meets twice a year with individual agendas covering either (i) food additives, contaminants and naturally occurring toxicants in food or (ii) residues of veterinary drugs in food. At JECFA's site, it is possible to find publications, guidelines, transparent process information, and projects.

Federal and international agencies, private sector organizations, and academics use terms and definitions differently in their microbial risk assessments. This Thesaurus is a compendium of risk assessment terms found in frameworks, methodologies, and assessments. It provides insight into how various entities use specific microbial risk assessment terms in their activities and helps those responsible for such assessments both conduct and communicate about them more effectively. This Thesaurus was developed by the USEPA, Office of Water

The purpose of this paper is to provide a description of the conceptual framework for quantitative microbial risk assessment within the standard description provided by the National Academy of Sciences (NAS) paradigm.

Each of the sequential steps in quantitative risk assessment, i.e., hazard identification, exposure assessment, dose-response assessment, and risk characterization, are discussed in detail, providing information on applications, tools for conducting the analyses, and methodological and/or data limitations.

This report describes an integrated scientific approach to supporting food safety decisions by utilizing veterinary and medical epidemiology, risk assessment for the farm-to-fork food chain, and agricultural and health economics. Included are discussions on the policy cycle, the food safety problem in general, prioritizing health impacts, and policy implementation. Also included are risk assessment models and data and a discussion on economics.

Science and Decisions makes practical scientific and technical recommendations to address these challenges. This book is a complement to the widely used 1983 National Academies book, Risk Assessment in he Federal Government (also known as the Red Book). The earlier book established a framework for the concepts and conduct of risk assessment that has been adopted by numerous expert committees, regulatory agencies, and public health institutions. The new book embeds these concepts within a broader framework for risk-based decision-making. Together, these are essential references for those working in the regulatory and public health fields.

This presentation discusses Integrating Risk Assessment and Benefit-Cost Analysis. It was presented at the 2007 IRAC-sponsored Public Conference 'Risk Assessment, Economic Analysis, and Foodborne Illness Regulations'. All the agenda and presentation information can be found from this link.

The USDA's Food Safety and Inspection Service conducts food safety risk assessments related to chemical and microbiological hazards in meat, poultry, and egg products. These risk assessments are used to evaluate intervention strategies to reduce foodborne risks and to guide, support, and enhance the Agency's overall decision-making process, risk-management policies, outreach efforts, data collection initiatives, and research priorities. This page links to reports and models, as well as responses to peer review and public comments for FSIS risk assessments. Pathogen-commodity combinations addressed include BSE in cattle, E. coli O157:H7 in ground beef, Clostridium perfringens, Salmonella, and Listeria monocytogenes in ready-to-eat meat and poultry products, Salmonella spp. in egg products, and Salmonella Enteritidis in shell eggs

ORATS (Online EUropean Risk Assessment Tracking System) provides information on the progress of implementation of Council Regulation (EEC) No 793/93 also known as Existing Substances Regulation (ESR), introducing a comprehensive framework for the evaluation and control of "existing substances".

The Article 8 of the Regulation states that the Commission, in consultation with the Member States, will regularly draw up lists of priority substances which require immediate attention because of their potential effects to man or the environment. The Commission and Member States utilise the information collected during step I of the regulation (Data Collection) as a basis for selecting priority substances.

This website provides information on FAO/WHO activities related to microbiological risk assessment. It includes risk assessment and risk management documents, guidelines for conducting microbial risk assessment, related links, and more. JEMRA website may also be found here. 

This presentation was given at the 1st International Conference on Microbiological Risk Assessment: Foodborne Hazards, held in Adelphi, MD on July 24-26, 2002. It presents the principles of risk assessment from several sources (Codex, OIE, Society for Risk Analysis), discusses current modelling practices and problems associated with current risk analysis practices, and presents a case for focusing on decisions when performing risk analysis. The pdf version of this presentation is available here

This presentation was given at the 1st International Conference on Microbiological Risk Assessment: Foodborne Hazards, held in Adelphi, MD on July 24-26, 2002. It includes a discussion of the application of microbiological risk assessment (MRA) in industry, including the differences in purpose, scope, input, and output between governmental and industry use of MRA and the use of MRA and predictive modelling in industry. The pdf version of this presentation is available here

This presentation was given at the 1st International Conference on Microbiological Risk Assessment: Foodborne Hazards, held in Adelphi, MD on July 24-26, 2002. It describes laboratory experiments for studying cross- contamination, data analysis methods, results, bibliography of their published work, a listing of other research projects on microbial behavior in the kitchen environment, and other recent publications. It also presents other considerations for quantitative microbiological risk assessment associated with cross-contamination, and discusses the future outcomes of these types of studies as a means to improve cross contamination modules used in risk assessments. 

This presentation was given at the 1st International Conference on Microbiological Risk Assessment: Foodborne Hazards, held in Adelphi, MD on July 24-26, 2002. It presents a "risk assessment" of microbiological risk assessment. It includes an overview of the process of generating a risk assessment, identifies "hazards" associated with the risk assessment process, discusses solution sets and process characterization, offers a tiered approach to methodology development, and presents conclusions on the risk assessment process. 

This presentation was given at the 1st International Conference on Microbiological Risk Assessment: Foodborne Hazards, held in Adelphi, MD on July 24-26, 2002. It discusses the value of microbiological risk assessment and contrasts developing and developed countries, including what drives food safety systems, what are the priorities related to food safety, and what important factors are weak or lacking in developing countries. Finally, it presents ways to build capabilities for microbiological risk assessment in developing countries, with an emphasis on the need to enhance scientific and technical expertise. The pdf version of this presentation is available here

This report includes an overview of the CFSAN risk analysis framework, a description of a decision-based approach to identify and select risk assessments, a discussion of conducting risk assessment within the risk analysis framework, examples of communication questions between risk assessors and risk managers, a list of risk communication activities, criteria for identifying candidate risk assessments, and criteria for evaluating technical feasibility