Sarah Cahill Ph.D. is a microbiologist and an Associate Professional Officer in the Food Quality and Standards Service, FAO Food and Nutrition Division.
Food safety has always been an important issue, and currently it is high on the political agenda of many countries. The reasons for this are manifold. More than ever before, there is strong consumer awareness of food quality and safety, and this continues to increase. New risks and challenges are emerging as a result of changes in the methods of food production at the farm and processing levels. Further challenges arise from the emergence and re-emergence of food-borne pathogens. Consumption patterns are changing and consumer demands regarding such issues as the variety and shelf-life of foods, as well as the preservation techniques used, are changing. Furthermore, the expansion of international trade in food has also increased the risk of infectious agents being disseminated from the original point of production to locations thousands of kilometres away. The consequence of this is that there is an increased risk to human health as well as implications for international trade in food.
Risk analysis has evolved over the last decade within the Codex Alimentarius Commission (CAC). Since the Uruguay Round Trade Agreement on the Application of Sanitary and Phytosanitary Measures (SPS) entered into force in 1995, the importance of risk analysis has increased. Risk analysis is now considered to be an integral part of the decision-making process of Codex. CAC has adopted definitions of risk analysis terms related to food safety and statements of principle relating to the role of food safety risk assessment. Furthermore, in 1999, it adopted the Principles and Guidelines for the Conduct of Microbiological Risk Assessment (CAC, 1999a). These were developed by the Codex Committee on Food Hygiene (CCFH), which is currently developing Principles and Guidelines for the Conduct of Microbiological Risk Management.
In addition to these developments in risk assessment, the 22nd Session of CAC requested FAO and the World Health Organization (WHO) to convene an international advisory body on the microbiological aspects of food safety in order to address, in particular, microbiological risk assessments (CAC, 1997). In response to this and as follow-up on their previous activities in the area of risk analysis, FAO and WHO convened an expert consultation in March 1999 to examine the issue of microbiological risk assessment (MRA) in an international forum. The main outcome of this expert consultation was an outline strategy and mechanism for addressing MRA at the international level (Box 1).
The risk assessment process provides
an estimate of the probability and
severity of illness attributable to
a pathogen-commodity combination
Subsequently, at its 32nd Session in November 1999, CCFH recognized that there are significant public health problems related to microbiological hazards in foods (CAC, 1999b). It identified 21 pathogen-commodity combinations of concern and prioritized these according to such criteria as the significance of the public health problem, the extent of the problem in relation to geographic distribution and international trade and the availability of data and other information with which to conduct a risk assessment. CCFH suggested that FAO and WHO convene ad hoc expert consultations to provide advice on MRA, and also recommended that these consultations be conducted according to the format outlined at the 1999 expert consultation (Box 1).
BOX 1 Recommendations of the Joint FAO/WHO Expert Consultation on Microbiological Risk Assessment, 1999 "A vehicle for the provision of expert advice on microbiological food safety risk assessment should be established by FAO and WHO. Initially this vehicle should take the form of a series of meetings of experts ...". The scope of the meetings should be to: The primary outputs of expert consultations should be: Source: WHO, 1999. |
Risk assessment is one of the components of risk analysis - which can be defined as being an overall strategy for addressing risk that includes risk management and risk communication. The importance of an overlap between these three elements (risk assessment, risk management and risk communication) is well recognized, but some functional separation is also necessary. In relation to risk assessment, such separation ensures that issues are addressed in a transparent manner using a scientific basis. CAC defines risk assessment as a scientifically based process consisting of the following four steps: i) hazard identification; ii) hazard characterization; iii) exposure assessment; and iv) risk characterization. The risk assessment process is a means of providing an estimate of the probability and severity of illness attributable to a particular pathogen-commodity combination. The four-step process enables this to be carried out in a systematic manner, but the extent to which the steps are carried out will be dependent on the scope of the risk assessment. This can be defined clearly by the risk manager through ongoing dialogue with the risk assessor.
The carrying out of an MRA is recognized as a resource-intensive task requiring a multidisciplinary approach. While MRA is becoming an important tool for assessing the risks to human health from food-borne pathogens and can be used in the elaboration of standards for food in international trade, it is not within the capacity of many, perhaps most, countries to carry out a complete MRA. Yet, food-borne illness is among the most widespread public health problems and creates social and economic burdens as well as human suffering, making it a concern that all countries need to address. Risk assessment is a tool that can be used in the management of the risks posed by food-borne pathogens.
On the other hand, risk assessment can also be used to justify the introduction of more stringent standards for imported foods. A knowledge of MRA is therefore also important for trade purposes, and there is a need to provide countries with the tools for understanding and, if possible, carrying out MRA. This need, combined with CAC's and CCFH's requests for scientific advice on MRA, has led FAO and WHO to undertake a programme of activities to address the issue of MRA at the international level (Figure).
FAO/WHO activities on risk assessment of microbiological hazards in foods
|
The aim of the joint programme is to provide a transparent review of scientific opinion on the state of the art of MRA, and to develop the means of achieving sound quantitative risk assessments of specific pathogen-commodity combinations. The work includes an evaluation of existing risk assessments; a review of the available data and current risk assessment methodologies, highlighting their strengths and weaknesses and how they may be applied; provision of examples; and identification of ongoing data and information needs. As it is developed, such information is being made accessible through the FAO Web site.
The work is currently focusing on the following pathogen-commodity comb-inations:
Salmonellosis is one of the most frequently reported food-borne diseases worldwide, with poultry and poultry products being common vehicles of the disease. The annual incidence of Salmonellosis in the United States, for example, is estimated at 1.4 million cases but more than 99 percent of patients recover fully (CDC, 2000). Listeriosis, on the other hand, is a relatively rare disease, but when it does occur it can be severe with fatality rates of 20 to 30 percent among hospitalized patients (McLaughlin, 1996).
Expert drafting groups were established to address the first three steps of risk assessment - i.e. hazard identification, exposure assessment and hazard characterization - for these pathogen-commodity combinations. Hazard identification is the identification of the biological agent capable of causing the adverse health effects that may be present in a particular food or group of foods. Exposure assessment is the qualitative and/or quantitative evaluation of the likely intake of the biological agent via food, as well as via exposure from other sources, if relevant. Hazard characterization is the qualitative and/or quantitative evaluation of the nature of the adverse health effects associated with the biological agents that may be present in food, and in such cases a dose-response assessment should be performed if the data are obtainable.
In October 2000, five technical documents were prepared, the contents of which are summarized in the Table. In addition to providing in-depth analysis of hazard characterization and an exposure assessment of the specific pathogen combinations, each document identifies gaps in the data that need to be filled, makes recommendations for future work and includes an extensive bibliography of relevant data and information sources.
A further aim of this joint FAO/WHO undertaking on MRA is the development of guidelines relating to the different steps of risk assessment, such as hazard characterization and exposure assessment. The purpose of such guidelines is to help the risk assessor, the risk manager and other interested parties to understand the principles and science behind the risk assessment steps. The guidelines document was initiated during a workshop on hazard characterization in June 2000, and a preliminary text has been elaborated. This text includes guidance on the types of data needed and the means of assessing the adequacy of available data as well as information on the process, principles and methods of hazard characterization.
The technical documents and the guidelines on hazard characterization were reviewed by an expert consultation at FAO headquarters in Rome on 17 to 21 July 2000. The purpose of this meeting was to obtain an expert review of, and input into, the documentation developed so as to continue its elaboration, as well as to provide scientific advice to FAO and WHO member countries and Codex on the risk assessment of Salmonella spp. in broilers and eggs and of Listeria monocytogenes in ready-to-eat foods.
Summary of contents of the technical documents | |
Title and authors |
Summary of contents |
1. Hazard identification and hazard characterization of Salmonella in broilers and eggs. A. Fazil, R. Morales, A. Lammerding, |
Aim: To evaluate the nature of the adverse health
effects associated with food-borne non-typhoid and non-paratyphoid Salmonella spp. and to assess the
dose-response relationship.1 |
2. Exposure assessment of Salmonella Enteritidis in eggs. E. Ebel, F. Kasagu, |
Aim: To compare existing techniques and practices used to construct an exposure assessment for S. enteritidis in eggs and provide a framework for future exposure assessments. |
3. Exposure assessment of Salmonella spp. in broilers. L. Kelly, W. Anderson and E. Snary. |
Aim: To develop a model framework, highlighting ideal data requirements and possible methodologies for Salmonella spp. in broilers because, to date, no full quantitative exposure assessments have been undertaken. |
4. Hazard identification and hazard characterization of Listeria monocytogenes in ready-to-eat foods. R. Buchanan and |
Aim: Quantitative evaluation of the nature of the adverse health effects associated with L. monocytogenes in ready-to-eat foods, and assessment of the relationship between the dose and the response. |
5. Exposure assessment of L. monocytogenes in ready-to-eat foods. T. Ross, E. Todd and M. Smith. |
Aim: To provide an overview of issues to be considered in exposure assessment, a description and evaluation of the methods that can be used and the available information, and to demonstrate the application of exposure assessment. |
1 The dose-response relationship is the relationship between the magnitude of the exposure (the dose) to the biological agent and the severity and/or frequency of associated adverse health effects (the response). | |
The expert consultation noted that MRAs could have a wide range of applications in food safety. Ideally, a risk assessment should encompass all components of the food system, from production to consumption, so that risk factors and strategies to reduce them can be thoroughly described. An MRA can be used for a number of purposes, including to create broad food safety policies, develop sanitary measures that achieve specific food safety goals and elaborate standards for food.
The consultation recognized the comprehensiveness and scientific value of the technical reports presented and concluded that they considerably advance current knowledge on the general development of hazard characterization and exposure assessments. The reports also enhance specific knowledge in relation to the pathogen-commodity combinations identified as significant food safety problems by CCFH. In the absence of specific risk management guidance, the consultation endorsed the approach taken by FAO, WHO and the expert drafting groups in developing hazard characterizations and exposure assessments for L. monocytogenes in ready-to-eat foods and Salmonella spp. in broilers and eggs. Although not tailored to achieve specified risk management goals, this practical approach advances international understanding in a broad sense and provides a strong platform for future provision of risk assessment advice as requested by FAO and WHO member countries CCFH and other stakeholders.
The expert consultation recognized that international scientific cooperation and peer review are essential to the development of credible hazard characterization and exposure assessments for the purpose of risk characterization. It agreed on the general applicability of modelling approaches taken and reflected on the critical importance of adequate data input to satisfy risk management goals. It also recognized technical areas where scientific consensus has not been achieved, and ongoing scientific dialogue is necessary to resolve such issues. The consultation stressed that the purpose and scope of individual risk assessments will influence data acquisition needs.
A microbiological risk assessment can be used
to create broad food safety policies, develop sanitary measures that achieve specific food safety goals and
elaborate standards for food
BOX 2 Recommendations of the Joint FAO/WHO 17 to 21 July 2000, FAO headquarters, Rome1 The consultation recommended that FAO and WHO should: In addition, the consultation recommended that: 1 FAO, 2000 |
It was emphasized that FAO and WHO need to continue their support of expert consultations in relation to completing risk assessment of the pathogen-commodity combinations identified as significant food safety problems by CCFH. It was also stressed that such risk assessments need to be applicable to developing countries and that specific data requirements are needed to achieve this. Likewise, it was recognized that a prerequisite for further development of MRA in developing countries is the provision of appropriate technical advice, assistance and training. The recommendations of the expert consultation are outlined in Box 2.
The report of the consultation, the technical documents on hazard characterization and exposure assessment, and the draft guidelines for hazard characterization are available on the FAO Web site at: www.fao.org/waicent/faoinfo/economic/esn/pagerisk/riskpage.htm
|
The expert consultation and the technical documents identify a number of issues that should be addressed before risk assessment of these pathogen-commodity combinations can be completed. In particular, there is a need for additional data, better access to relevant data collected by government and industry, and guidance from risk managers on the risk reduction measures to be considered in the further elaboration of the risk assessments and the target population of the risk estimate. The technical documents prepared by the expert drafting groups have been posted on the FAO Web site for public comment. All comments on the scientific content of the reports, and of additional relevant scientific data and information, will be considered by FAO and WHO and, where pertinent, will be taken into account in the revision of the technical documents by the expert drafting groups. During the next year the final step of the risk assessment process (risk characterization) will integrate the three previous steps, in order to obtain a risk estimate that provides a qualitative or quantitative forecast of the likelihood and severity of adverse effects in a given population. The reports on risk characterization will be reviewed by a Joint FAO/WHO Expert Consultation on Microbiological Risk Assessment, to be held in 2001 with the aim of finalizing the risk assessments of Salmonella spp. in broilers and eggs and L. monocytogenes in ready-to-eat foods by October 2001.
REFERENCES
CAC. 1997. Report of the 22nd Session of the Joint FAO/WHO Codex Alimentarius Commission, Geneva, 23 to 28 June 1997.
CAC. 1999a. Principles and Guidelines for the Conduct of Microbiological Risk Assessment, CAC/GL-30.
CAC. 1999b. Report of the 32nd Session of the Codex Committee on Food Hygiene, Washington, DC, 29 November to 4 December 1999.
CDC. 2000. Salmonellosis: technical information. From Centers for Disease Control and Prevention (CDC) at: www.cdc.gov/ncidod/dbmd/diseaseinfo/salmonellosis_t.htm
FAO. 2000. Report of the Joint FAO/WHO Expert Consultation on Risk Assessment of Microbiological Hazards in Food. Rome, 17 to 21 July 2000.
McLaughlin, J. 1996. The relationship between Listeria and listeriosis. Food Control 7(4-5): 187-193.
WHO. 1999. Risk assessment of microbiological hazards in foods. Report of a Joint FAO/WHO Expert Consultation, Geneva, 15 to 19 March 1999.
