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CHAPTER 1 EXECUTIVE SUMMARY The production, slaughter, and distribution of broiler chickens (fryers) has become a major food industry that touches the lives of most Americans. Poultry products are currently consumed at a rate of well over 4 billion birds per year in the United States. Those products that pass through the inspection system required by law are, for the most part, wholesome. But because these products are potentially important vehicles of bacterial and chemical contaminants, the primary government agency charged with the oversight of poultry slaughter, the Food Safety and Inspection Service (FSIS) of the U. S. Department of Agriculture (USDA), has for the past decade been attempting to improve the effectiveness of poultry inspection by studying, testing, and reviewing several modifications of the existing program. Its goal has been to develop a system that retains the bird-by-bird inspection mandated by law, incorporates new technological advances, and more directly addresses public health concerns. In 1983, recognizing the need to evaluate these proposed changes in inspection procedures, the Administrator of FSIS requested that the Food and Nutrition Board (FNB) of the National Research Council (NRC) examine the scientific basis of USDA's meat and poultry inspection program. The committee appointed to perform that task, the Commi ttee on the Scientific Basis of the Nation's Meat and Poultry Inspection Programs, thoroughly evaluated current FSIS inspection programs. During the course of its study of those programs the committee observed that it could not find a comprehensive statement of criteria justifying inspection procedures, a systematic data base on contaminants, or a technically complete analysis of the benefits to human health resulting from the inspection process. That is, in general it found that it is not possible to determine from existing data whether current inspection programs actually fulfill their goal of protecting the public health. That committee considered whether to recommend a move to one of the newly proposed, less-than-continuous postmortem inspection systems but concluded that no such changes should be reco~runended until justified by a detailed risk analysis of the public health risks involved. It recommended that FSIS establish a risk-assessment Program and aPPlY formal risk-assessment procedures to assist in planning and evaluating all phases of poultry production in which hazards to public health might occur. 1 , ~ ~ . , . . .
2 IN response to that committee's assessment, which was published in 1985, FSIS requested that ENB conduct another study to develop a risk-assessment model for comparing the effects on public health that might result from different postmortem inspection goals and strategies, to evaluate the public health risks associated with broiler chickens, and to review the advantages of a sampling program as part of an overall quality assurance program for poultry slaughter This report describes the findings of the Committee on Public Health Risk Assessment of USDA Poultry Inspection Programs, which was appointed to conduct the second study. The committee began its task by reviewing the ways in which traditional and new inspection procedures are related to public health. It soon decided that to evaluate poultry-related public health risks properly, it would be necessary to consider in addition to postmortem inspection various aspects of the poultry processing system outside the purview of FSIS, for example, growing conditions, preparation and handling, and cooking. ~ . . . . ~ in. .. . . . Viewing the poultry processing system as a whole, the comm' ttee developed a conceptual risk- assessment model that could serve as a prototype for assessing public health risks associated with the entire spectrum of activities involved in poultry production, slaughter, processing, preparation, and consumption (referred to in this s~'rnmary as the poultry system). It then evaluated the two most important health hazards associated with poultry--microbial and chemical contaminants- within the context of the model. The conclus ions and recommendations described in the following paragraphs derive from the committee' s qualitative application of the model to the available information on poultry health hazards . S ince the current data base is essentially the some as that used in the 1985 report, the present committee did not conduct another comprehens ive evaluation of the FSIS poultry inspection program buts rather, focused on developing the r~sk-assessment model and delineating how it might be used to evaluate FSIS programs. As requested by FSIS, emphasis in this report has been placed on the use of risk assessment as a tool for evaluation. Some aspects of risk management that may lead to solutions of risk problems by FSIS are briefly described in Chapters 3, 4, and 50 _ . _ . GENERAL CONCLUS IONS The committee concluded that a risk-assessment approach is needed to evaluate health hazards associated with poultry Accordingly, it developed a risk model, which is divided into submodels representing f ive different phases of the poultry system . These submodels are . . . tThe committee ' s report, Meat and Poultry Inspection: The Scientific Basis of the Nation's Program' was published by the National Academy Press.
3 further broken down into various components. The model can be used to identify sources of health hazards, to suggest means of controlling their introduction, and to assess uncertainties in the ability to link public health consequences with specific hazards. Because the structure of any model reflects the particular perspective and knowledge of its designers, the conclusions and recommendations of the committee based on its model reflect its perception of how the poultry industry is most logically and usefully subdivided. As stated in Chapter 3, the committee concluded that the present system of continuous inspection provides little opportunity to detect or control the most significant health risks associated with broiler chickens. Although information is not sufficient for the committee to conclude that the FSIS inspection program has no public health benefits, the weight of the evidence does suggest that the current program can not provide effective protection against the risks presented by microbial agents that are pathogenic to humans. The committee concluded that risk assessment is one of the most valuable tools available to serve regulatory agencies such as FSIS because it facilitates a structured approach to the evaluation of information as well as an explicit, consistent, and logical treatment of data. Furthermore, it heightens awareness of uncertainties in the data and entails consideration of current scientific knowledge. If risk assessment were to be used by FSIS to identify health hazards associated with poultry, the most likely outcome would be to reduce public exposure to those hazards. This outcome would be dependent on implementing procedures that assign priorities based on the potential for reducing the magnitude of risk associated with a given hazard and on the prevention of risks instead of coping with them after they are present. An effective risk-management program will consist of several monitoring activities, some of which are outside FSIS authority. Therefore, a comprehensive effort to protect the public from poultry-associated hazards will require an active and consistent liaison between FSIS and other government agencies. Attempts to control these public health risks could be significantly compromised without such interagency cooperation. The committee confirmed that the current data base can serve as the basis for a comprehensive, quantitative risk assessment only for certain well-characterized chemical residues. For many purposes, however, including initial planning and evaluation of inspection strategies, it is sufficient and useful to perform qualitative assessments, such as that done by the committee in this report. GENERAL RECOMMENDATIONS . · FSIS should adopt the well-established precepts of risk assessment as an integral part of its strategy to identify and manage
4 public health risks associated with poultry. The committee's risk model can serve as a prototype that FSIS can refine by applying its extensive knowledge of the poultry system. · FSIS should evaluate the current inspection system by using the risk-assessment model proposed by the committee and on the basis of its findings, modify the system so that it more directly addresses public health concerns. · Rather than focusing on one procedure, such as bird-by-bird inspection, as the primary component of an inspection process, FSIS should direct its efforts toward the establishment of a comprehensive quality assurance program. Such a program would consist of several components, one of which might be organoleptic inspection. · Emphasis should be shifted from detection to prevention of problems at the earliest feasible stage in production to increase the effectiveness of poultry risk-management activities. A RISK-ASSESSMENT_MODEL FOR POULTRY-ASSOCIATED HAZARDS The process of risk assessment requires first a conceptual framework and second a risk model. For its conceptual framework, the committee adopted the well-accepted view of the role and nature of risk assessment developed in 1983 by the National Research Council's Committee on the Institutional Means for Assessment of Risks to Public Health9 which proposed that risk assessment proceed in four steps: hazard identification, dose-response assessment, exposure assessment, and risk characterization. The use of these four steps helps to ensure the inclusion of all factors that determine risk. Successful execution of the final step, risk characterization, is dependent on the development and application of a model such as that proposed by the committee in Chapter 3. In developing its model, the committee reviewed the major risk agents (pathogenic microorganisms or their toxins, and chemical residues) associated with the five major divisions (or submodels) of the poultry system: production (grow-out); slaughter; packing and processing; distribution and preparation; and consumption. The model includes all phases of processing in which hazards might be present, the sources from which risk agents are generated or released, routes of human exposure, and mechanisms by which the exposure can result in adverse health effects. The model provides one possible approach to the evaluation of current FSIS inspection programs. It can serve as a guide in the development of future programs and assist in determining the level of public health protection afforded by current inspection procedures. Conclus ions · The committee concluded that by conducting a qualitative examination of each component of the risk model it is possible to identify potential sources of health hazards and to suggest means of preventing their introduction.
s · The committee's assessment suggests that to minimize public health risks, the traditional focus on slaughter should be expanded to include other potential sources of poultry-related hazards, such as production, preparation and handling, and cooking. · Although qualitative risk assessments, such as those undertaken by the committee, are often sufficient to identify hazards and their probable sources, quantitative assessments are required to establish the validity and mechanisms of cause-and-effect relationships and to identify the magnitude of public health problems. · As FSIS evaluates the poultry processing system with the objective of increasing public health protection, its managerial personnel will have to identify those circumstances in which quantitative assessments are justified on the basis of additional insights or improved clarity that they could lend to the dec~sion- making process. Recommendations · The committee's risk model should be regarded as a prototype that FSIS can modify and refine to suit its own special needs and goals. · FSIS should attempt to ensure that all aspects of the poultry system are included in any risk model used, even if certain areas fall within the purview of other agencies. · Qualitative risk assessments should form the initial bases for planning and selecting inspection and quality assurance programs. Quantitative assessments should be used when qualitative assessments prove inadequate and when sufficient data are available. MICROBIOLOGICAL HAZARDS AND POULTRY Salmonella species and CampYlobacter jejuni from all sources (i.e., not from chickens alone) are each responsible for up to 2,000 cases of gastroenteric disease per 100,000 people per year in the United States. Illnesses caused by these microorganisms tend to be most severe among the very young, the very old, or patients with immunosuppressive diseases. The rate of infection tends to increase with increasing size of the inoculum (dose), although a relatively low inoculum is sometimes capable of causing disease in humans. The potential for introduction of Salmonella and CampYlobacter, the most commonly encountered human pathogens on chicken, is highly variable and may occur at multiple points during production, slaughter, and processing. After reviewing data related to the occurrence, potential for causing infection, and pathogenicity for humans of several microbial species known to be present on chicken, the committee drew the following conclusions, which are described in greater detail in Chapter 4.
6 Conclus ions · Current inspection programs are not designed to detect the most important human pathogens found on poultry. This is evident from the reviews of PSIS inspection programs conducted by the present committee and the earlier Co~ranittee on the Scientific Basis of the Nation's Meat and Poultry Inspection Program. · Minimizing microbial contaminants on poultry is a worthwhile obj ective, but it is premature to establish formal microbiological criteria for classifying raw products as microbiologically acceptable or unacceptable. The committee concluded that the data required to j ustify such formal regulatory standards do not exist . .- · There is conclusive evidence that microorganisms pathogenic to humans (such as Salmonella and Campylobacter) are present on poultry at the time of slaughter and at retail. · There ~ s evidence linking disease in humans to the presence of pathogens on chickens . For example, epidemiological studies indicate that approximately 48% of Campylobacter infections are attributable to chicken. Data also suggest that chicken is probably an important source of salmonellosis in the United States. · It is not known with certainty whether bacteria, viruses, and parasites that are common causes of disease in poultry can serve as food-borne pathogens for humans. Most of these organisms do not appear to be pathogenic in humans, but some may be. Thus, more data ore the pathogenicity of these organisms are needed. Recommendations The association between microorganisms in and on poultry at slaughter and the occurrence of disease in humans is complex. Several potential sources of contamination exist throughout the poultry system. The committee recc~gn' zes, therefore, that attempts to resolve this problem will be correspondingly cliff icult and may require collaboration with other agencies. On the basis of its review of the literature and established principles of microbiology, however, the committee recommends that certain actions such as the following be taken to reduce the potential for disease to be caused by poultry-borne . . mlcroorganlsms. · The ongoing search for data on microbial risks should continue and be complemented by new research. Emphasis should be placed on the prevention of human disease rather than on simple control of microbial counts during slaughter and processing. ~ Potentially pathogenic microorganisms on poultry should be i dentified, the potential for exposure to an infectious dose of each pathogen should be determined, and the potential impact on public health that would result from the failure to control exposures should be evaluated. ~ The critical control points at which known pathogenic microorganisms such as Salmonella and Campylobacter may be introduced into the poultry system should be identified and monitored, preferably
7 as a part of an HACCP (Hazard Analysis Critical Control Point) program. · A population-based surveillance program should be established so that disease occurrence can be correlated with inspection strategies. This will require measuring the level of pathogenic microorganisms on market-ready poultry as well as establishing a system for surveillance of disease within a well-defined population. O A range of educational programs for people who raise poultry and for those who handle raw broilers in slaughterhouses, at retail, and during food preparation in the home and commercial establishments should be developed or intensified. As part of this effort, poultry products should be labeled at retail to inform consumers how to handle the poultry to prevent diseases originating from microbial contaminants. CHEFII CAL HAZARDS AND POULTRY The 1985 report Meat and Poultry Inspection contained a description and evaluation of the National Residue Program (NRP), which is the only formal program for monitoring chemical contaminants in poultry. In that report the committee concluded that the fundamental design of NRP needs to be improved to ensure protection from chemical hazards. In particular, it questioned the adequacy of sampling sizes and procedures, the basis for and the utility of tolerance levels as currently set, and the basis for setting priorities for testing. In light of these conclusions, the present committee approached its analys is of chemical risks by reviewing the current status of toxicological testing used in chemical risk assessments, by describing where information and data are needed to appropriately characterize various classes of chemicals, and by delineating eight necessary components of a program for controlling chemical contaminants (see Chapter 5 ~ . After examining data on the identification, toxicological properties, and occurrence of chemical hazards in poultry, and considering this information in the context of its model, the committee reached the conclusions listed below. Conclus ions · Adequate methods exist for identifying chemical hazards in poultry and estimating their toxicity. Toxicological risks associated with a wide variety of chemicals, including herbicides, pesticides, food additives, and food and drinking water contaminants, have for several years been assessed on the basis of data obtained from experiments in animals. These methods of risk assessment can be used for chemical contaminants in poultry, although to date they have been applied primarily to other routes of exposure. ~ The entry of chemical residues into poultry can be controlled with approaches adopted by the Environmental Protection Agency (EPA) and the Food and Drug Administration (FOA). These agencies have well- established procedures for systematically determining permissible levels of exposure to toxic chemicals and managing the points of entry
8 of such substances into various types of environments. These procedures include such steps as establishing acceptable daily intakes, determining residue levels at which no observable toxic effects occur, and setting priorities based on the relative magnitude of various hazards. The toxicological data bases used by these agencies may not, however, be completely adequate to set 1~ mits for all chemical residues in poultry. · A comprehensive approach to the control of chemical res idues is not now possible. Of the four classes of chemicals categorized by the committee according to source, adequate data on occurrence exist for only one: chemicals that are intentionally added to poultry feed and water or are given to poultry to modify growth or prevent disease. Thus, there is a need to identify contaminants from several other sources and to determine which of them present the greatest potentially reducible risks and should therefore receive highest priority in a control program. · Risks attributable to chemical residues in poultry should be assessed on a routine basis, because new chemicals may be introduced intentionally or accidentally into the environment at any time and because the data base is constantly growing. For examples there is a continual increase in information on the safety of environmental chemicals, especially on subchronic and chronic toxicity, on the basic biochemistry of toxicological effects, and on the relevance of toxic effects in animal models to humans. · A comprehensive analys is of the risk of chemical res idues in poultry was not possible, but in examining the limited data available the committee found no evidence that such residues pose a significant threat to public health. Recommendations The committee' s major recommendations regarding chemical residues are based on its observation that important sources of residues are not considered in the FSIS monitoring program and that priorities for risk management are currently not set according to the relative magnitude of risk for known residues. If adopted by FSIS, the following recommendations should result in distinct improvements in the residue program: · Using degree of risk as a basis, FSIS should establish priorities for monitoring residues and associated activities. · Potentially hazardous chemical residues in poultry and their points of origin should be identified. · The risks associated with identified hazardous residues should be determined. · Using known risks as a basis, FSIS in collaboration with EPA and FDA should ensure that tolerance levels are set for known hazardous residues. O Control programs to monitor the entry of residues into poultry . should be developed. FSIS should determine how chemically contaminated poultry might
9 be removed from the marketplace or production line. CURRENT FSIS PROGRAMS AND STATISTICALLY BASED SAMPLING Current poultry inspection procedures focus primarily on the removal of diseased and damaged chickens, which are identified by organoleptic inspection techniques: observing, smelling, and feeling . These objectives, along with maintaining a sanitary environment, are valid components of any food- related quality assurance program, but should not be the only goals. This traditional approach to inspection can provide a foundation for the control of public health risks, but an effective program requires a broadened scope of activities based on quality assurance principles. Over several decades, detailed studies of quality assurance techniques in diverse fields of production and manufacture have shown that prevention of problems is the most effective means of controlling product quality. Such studies have shown that optimal product quality is most efficiently achieved through continuous monitoring based on a well-planned sampling protocol. A statistically based sampling scheme as part of a comprehensive quality assurance program for poultry would therefore offer advantages such as the following: · Management of contamination by preventing its introduction at the source. · Quick response to accidental contamination and the ability to trace defective birds to their sources. · Continuous monitoring to observe the effects that result from adjusting variables in the program. · Greater flexibility of data applications and more efficient use of resources. · Application of data to quantitative risk assessments when necessary. · Examination of birds, both microscopically and microscopically, as dictated by need. It should not be inferred that in such a program current inspection procedures would be applied to a smaller but more select sample of birds . Instead, a formal sampling system (as described in Chapter 7 necessarily involves more thorough examination of a well - defined but random group of birds; it might incorporate, for example, two conventional stages used continuously and ~ third stage for special programs, as follows: In the first stage, a subset of birds could be randomly sampled and i nspected in detail for general faults and gross disease . In the second stage, a smaller subs~n~ple could be randomly selected for more detailed study, including microbial load and simple chemical tests at the plant. In the third stage, a further random subsample of the second-stage sample could be frozen or otherwise preserved and sent to a central laboratory for studies not feasible at the plant, e.g., for
10 testing in the National Residue Program. This final subs~mple should be subjected to morphologic and etiologic diagnoses to help build a data base against which future program activities can be measured. In each case, the rate of sampling and other details of the sampling process should be optimized on the basis of the best available information and the objectives of the inspection process. For example, the sampling rate might be periodically increased or decreased, depending on whether the results of previous samples and other information suggest an increase or decrease in the probability of encountering significant problems. The committee emphasizes, however, that less frequent but more intense examination of samples of chickens is not a substitute for maintaining a sanitary environment and that expert technical support and planning are required to ensure maximum benefits from such a program. Conclusions · The committee concluded that current procedures for selecting poultry samples for analysis of chemical contaminants are limited and are not sufficiently flexible to meet the needs of an expanding incus try O For example, at the current monitoring rate of 300 samples per year, some plants may not be sampled for extended periods. Thus, even major problems might not be addressed in a timely manner. · The current FSIS objective of ensuring a 95% probability of finding a chemical contaminant in a minimum of 1% of slaughtered poultry does not take into account the possibility of isolated accidental contaminations. · Technical problems include lack of random sampling, absence of a system for continuous collection of data, lack of alternatives to simple random sampling (e.g., different rates of sampling, stratified random sampling), absence of flexibility to increase sample fractions under specific circumstances (e.g., when many birds are septicemic, when evisceration equipment malfunctions, or when a sampled bird dies of causes other than slaughter), and the inability to ensure that statistical variances are calculated correctly for data from complex samples. Recommendations o FSIS should begin to lay the groundwork for shifting resources from the organoleptic inspection of each broiler chicken to a more comprehensive program with statistically based sampling as one of its primary features. This should be undertaken as a first step in modifying the traditional bird-by-bird inspection system. · FSIS should shift the focus of its residue program from the detection of contaminants in market-ready products to the prevention of their introduction at points as early as possible in the production process. · Federal government support of broiler chicken inspection and related activities should be allocated primarily according to the degree that it can contribute to reductions in public health risk. The
11 current postmortem poultry inspection system does not address or meet thi s obj ective . · A shift in the focus of FSIS programs toward the identification of contamination sources would necessarily extend the agency's interests to areas that are now the respons ibility of other government ~ including state and local) agencies . FSIS should attempt to persuade such agencies that closer communication regarding poultry-associated health hazards is a matter of primary importance and that their effective control will require a concerted effort among responsible authorities. - The committee concluded, in agreement with the earlier Committee on the Scientific Basis of the Nation's Meat and Poultry Inspection Program, that FSIS should consider using risk-assessment techniques to manage and control poultry-associated hazards. Traditional poultry inspection techniques originated from the need to control diseases of poultry and to ensure a sanitary environment during slaughter. However, over the past few decades it has become apparent that the methods needed to detect and control poultry-associated public health threats are more complex than organoleptic inspection techniques alone can provide. The committee hopes that its risk model and its discussion of some potential applications will assist FSIS in controlling poultry-related health risks and developing a quality assurance program that will lead to nutritious and increasingly safe products.