Evaluating Risks and Establishing Food Safety Objectives and Performance Objectives
2.4 Evaluation of Risk .1 Introduction.1 Introduction
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The identity of the food source and conditions leading to foodborne illness may also be determined through epidemiologic investigations of outbreaks. Unfortunately, not all outbreaks are adequately investigated or described fully in the scientific literature, particularly those that do not provide new infor-mation. Consequently, that literature is often of limited use in relation to establishing the true frequency of their occurrence and thus the risk(s) associated with the disease agent. Case control studies can also be used to help identify the source(s) of sporadic cases of foodborne illness and the factors that contrib-ute to their frequency. Different sources may be more important in sporadic cases than in outbreaks. In the USA, outbreaks of Campylobacter jejuni infections in the spring and fall are typically caused by drinking raw unpasteurized milk or untreated water, whereas sporadic cases occurring in the summer appear related to touching or consuming uncooked poultry (Potter and Tauxe 1997; Tauxe 1992).
A sentinal study monitors selected health events in a group of persons representative of the whole population. Laboratory testing may be limited, e.g., to patients reporting diarrhea, or may include examination of all fecal samples for a range of pathogens. This approach, for instance, has been used to estimate the incidence of campylobacteriosis and salmonellosis in The Netherlands (Notermans and Hoogenboom-Verdegaal 1992) and England (Wheeler et al. 1999; FSA 2000).
However, much of the information collated regarding foodborne illnesses by different systems can-not be directly translated into policy since:
– not all cases are reported to health authorities, resulting in considerable uncertainty about the actual burden of illness
– often only a fraction of illnesses caused by food-related pathogens are actually foodborne because transmission can also be through the environment, direct contact with animals, or from person to person
– foodborne illnesses may vary both in incidence and severity, resulting in widely different clinical manifestations and potential likelihood of long-term sequelae.
Targeted studies in a number of countries have attempted to estimate the magnitude of underreport-ing. Mead et al. (1999) for instance estimated underreporting factors for different illnesses ranging from 2 for botulism and listeriosis, 20 for EHEC and shigellosis, and 38 for campylobacterioses and salmo-nellosis. In general, the estimates generated by such studies reflect a similar degree of magnitude in countries of similar economic development, demographics and healthcare infrastructure, but differences do exist. According to European studies similar to the one conducted in the USA, found the underreport-ing factors for campylobacteriosis were 7.6 (Wheeler et al. 1999) and 10.3 (Adak et al. 2002), while these studies reported underreporting factors of 3.2 and 3.9, respectively, for salmonellosis.
2.4 Evaluation of Risk
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Risk is a measure of the probability and consequence of uncertain future events (Gorris and Yoe 2014), which in the area of food safety can be reflected as:
Risk = Exposure to hazard * Consequence of exposure
Exposure to the hazard may be determined by the hazard concentration and prevalence in the food as well as the amount and frequency of the food consumed. There is an element of chance that expo-sure occurs, which needs to be accounted for when assessing risk. The consequence of expoexpo-sure then is characterized by the resulting outcome of exposure for the consumer, which usually is an adverse health effect, i.e. illness, but which can vary very significantly among consumers.Effective manage-ment of microbial hazards requires identification of the hazards, assessmanage-ment of the risks associated with those hazards, determination of possible options to mitigate risks and estimation of the effective-ness of the potential options to manage microbial hazards down to a tolerable level of risk. The strin-gency of control that the risk management option(s) of choice put on the food system should be proportional to the risk of the particular hazards to public health. This principle also underlies modern food safety management systems for food operations, such as Hazard Analysis Critical Control Point (HACCP), that are based on preventive strategies.
Historically, food control agencies and industry have relied on the judgement of one or more experts to estimate the risk and the corresponding level of control needed to manage it. Although this approach has often been successful, it can be biased or inconsistent. Further, it can be difficult to transparently communicate the underlying scientific basis and rationale for the decisions to interested parties because such evaluations have often been inadequately documented.
An improved approach is the use of structured safety assessments, typically including broader scien-tific expertise and more formal consideration of available data and information. This approach has been widely used in recent years where expert panels have been called to address various food safety issues, for instance psychrotrophic Clostridium botulinum in refrigerated foods with extended shelf life (ACMSF 1992), Listeria in ready-to-eat foods (Anonymous 1999, ICMSF 1994), Mycobacterium avium subspe-cies paratuberculosis in milk (NACMCF 2010), and Salmonella and norovirus in tomatoes (EFSA 2010).
Over the last decade, quantitative microbial risk assessment approaches have been initiated and more broadly adopted to systematically evaluate the impact of various factors such as the host, the pathogen, and the type of food (liquid, solid, fat) that contribute to the risk associated with a food-borne microbiological hazard.
Risk assessment is mentioned as a tool in the WTO/SPS agreement to assure that international trade in food is not hampered by unjustified safety requirements. This has led to an international har-monization of the concept and its practical implications by the Codex Alimentarius Commission (CAC 1999), although there is, as yet, no general (or international) agreement on when a quantitative risk assessment is necessary or which statistical/mathematical approaches are appropriate. Under the auspices of FAO and WHO, JEMRA has provided a range of international microbiological risk assess-ments and guidance docuassess-ments that are made available on dedicated websites of FAO and WHO.
There is a range of recent accessible resources on the principles of risk analysis (Moy 2014) and its component parts of risk management (Motarjemi and Moy 2014), risk assessment (Gorris and Yoe 2014;
Ross 2014) and risk communication (Motarjemi and Ross 2014) with regard to microbiological hazards.
The first step in any evaluation of risk is the identification of a food safety problem from one or more sources, such as accumulated epidemiologic data, governmental or intergovernmental bodies, public health sectors, the food industry, expert opinion/scientists, NGOs and consumers. Background information is generally assembled by a governmental risk manager, possibly with input of subject matter experts from public or private organizations, using readily available data and information to sufficiently describe the problem. In the Codex context, it has been advocated that the identification of a food safety problem is articulated through the development of a risk profile. Certain regions and countries around the globe have compiled risk profiles on pathogen-food combinations. For examples of risk profiles see, for instance, foodrisk.org/rm/riskprofile.
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On the basis of the information available on a particular food safety problem and the urgency con-sidered for its management, governmental risk managers must decide whether to direct risk assessors to initiate further studies and bring together a more elaborate qualitative or quantitative evaluation to obtain the information necessary for risk management decisions, e.g., understanding of the level of risk to (sub)populations of consumers, factors contributing to risk, possible risk mitigation options.
The purpose of a risk assessment is to enable a risk manager to make informed decisions. What form of risk assessment should be adequate for the risk manager to base their decision(s), and will depend on the food safety problem, factors such as the data/information already available or missing, and the feasibility to close key gaps in data/information with available resources in a timely manner. It is important that there is a common understanding of the problem between the risk managers and the risk assessors when a risk assessment is commissioned by the risk manager. This understanding should then include the risk assessment format to be taken (qualitative or quantitative assessment, deterministic or probabilistic), the available resources, time constraints, and the desired form of the output, e.g., a risk estimate (probability of disease per exposure or per year to the population or a sub- population) and/or suggested control measures. In the Codex context, for microbiological issues the Codex Committee for Food Hygiene (CCFH) acts as the risk manager and the Joint Expert meeting for Microbial Risk Assessment acts as the risk assessor, CCFH establishes a specific set of questions (i.e. FAO/WHO 2004) or a “terms of reference for scientific advice” (FAO/WHO 2008b) for JEMRA as the basis for the elaboration of an appropriate risk assessment.
Circumstances may lead a risk manager to seek the information needed for decision making first through a mainly qualitative evaluation (e.g., expert panel), commissioning a more detailed quantita-tive assessment as necessary. The best course of action likely is a case-by-case decision. Over the years, various organizations have shared learnings and resources. ILSI Europe for instances gathered experiences on the practical utility and validity of microbiological risk assessment for risk manage-ment (Lammerding 2007) and produced an overview of tools available for MRAs (Bassett et al.
2012). Several governments have published guidelines regarding MRA (FSANZ 2005; USDA/FSIS/
EPA 2012).
Basic aspects of both qualitative and quantitative risk assessments will be discussed in the follow-ing text. The use of expert panels as a form of qualitative risk assessment will be discussed first fol-lowed by quantitative risk assessment (see Sect. 2.7).
2.4.2 Use of Expert Panels
Control authorities, and others, have found expert panels to be an effective means to assemble infor-mation, interpret its content and develop recommendations in a relatively short period of time. Expert panels have been used extensively by governments and international bodies to address concerns about the safety related to a particular hazard-food combination or to provide other relevant food safety advice. Examples are the JEMRA consultations previously referred to, the various panels set-up under the European Food Safety Authority, such as the Panel on Biological Hazards (BIOHAZ), and the Advisory Committee on the Microbiological Safety of Food (ACMSF) and the National Advisory Committee on Microbiological Criteria for Foods (NACMCF) that informs multiple agencies with the US government. In addition, expert panels have been used by industry to consider the factors leading to foodborne disease and develop recommendations for their control (e.g., Nickelson et al. 1996;
Lammerding et al. 1999). Assessments by expert panels may be appropriate if advice is needed quickly to manage a newly recognized concern, if resources and/or data for a (quantitative) risk assessment are limited, or where there are few management options. Such panels are possibly also called upon when, in particular, epidemiological evidence indicates that a hazard is not under control and there is need for increased consumer protection. Furthermore, concerns may be raised following
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change in food habits, food processing technologies, and food packaging or distribution systems.
Such concerns must be evaluated and, if reasonable and supported by scientific evidence, appropriate management of the risk must be undertaken.
In practice, risk managers will call upon people with expertise on the particular pathogen and/or food in question and preferably contributing expertise from different scientific or technical areas.
Panels therefore may consist for instance of epidemiologists, public health specialists, risk analysts, food microbiologists and food technologists with knowledge about actual food processing operations, important for the evaluation. The panel will be asked to provide the best information available at that given point in time. Although the complexity of risk evaluations may vary case-by-case, panels typi-cally go through a range of steps that, following international risk analysis frameworks such as that of Codex (CAC 1999) are referred to as hazard identification, hazard characterization, exposure assess-ment and risk characterization. Typically, panels would accumulate available quantitative and qualita-tive data on the food safety problem at hand, develop a view on the risk to a consumer population or sub-populations, identify factors that contribute to risk or could mitigate risk, review options for risk managers to mitigate risk to lower levels possible following a number of scenarios of risk characteriza-tion and risk mitigacharacteriza-tion, and establish recommendacharacteriza-tions for risk managers to consider. The panels will also identify gaps in available data or where there are major aspects of uncertainty or variability in the assessment of the panel and communicate this to the risk managers. In some instances a rough estima-tion of the risks associated with different likely scenarios is sufficient. One approach is to assign rela-tive probability and impact rankings, such as negligible, low, medium, or high, to the factors used to determine likelihood of exposure and likelihood of an adverse outcome. If such a system is used, defi-nitions and rationale for assigned rankings must be clearly described and justified to avoid misinter-pretations of the information by users. An example follows in Chap. 8, where different hazards are ranked into categories dependent on the severity of the disease. The outcome from an expert panel may be to recommend to risk managers one or more measures to control a hazard or, if necessary, ban the product or process. Where appropriate, an expert panel may recommend the establishment of an FSO or PO where their work provides the necessary support that implementing such metrics could be an effective means to enhance consumer protection related to the particular hazard-food combination or the food safety situation under consideration. If there is significant uncertainty, the panels may recommend interim measures that should be taken until gaps in information and data can be addressed.
Chapters 14, 15, 16, 17, 18 and 19 are examples of risk evaluations conducted through the work of expert panels. Further discussion of the role of quantitative risk assessment in development of FSOs and POs is provided in Sect. 2.7.
