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~2 Food Safety Tools This chapter describes some of the major modern tools available to regula- tory agencies for use in developing food safety criteria and standards. Some of these techniques or concepts are widely known and extensively used, whereas others are still in the developmental stage. The description of these tools and the discussion of their current or potential uses and applications to enhance food safety have been organized as a progression from the better known to the novel. In addition, the committee strived to circumscribe the material on each tool to that which is relevant to food safety, recognizing that some of the sections, such as "Statistical Process Control" and "The Economics of Food Safety Criteria," are not only foreign to many food processors and food safety regulators, but are technical and scientific fields that only recently have been brought into play in the food safety arena. Thus, in view of the limitations in space and time facing the committee, the reader is referred to specialized treatises that expand on these areas when additional information is desired. HAZARD ANALYSIS AND CRITICAL CONTROL POINTS Introduction The Hazard Analysis and Critical Control Point (HACCP) system is a meth- odology that constitutes the foundation of the food safety assurance system in the modern world. Although a detailed history and description of HACCP principles and applications are beyond the scope of this report, the invaluable contribution that this food safety tool is making to improve public health, its central role in 69

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70 SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD present-day food processing, and its inseparable relationship to the issues dis- cussed in this report demand a short introduction and description of it. HACCP history goes back to 1959, when the National Aeronautics and Space Administration (NASA) commissioned the Pillsbury Company to manu- facture food products for use by astronauts during space missions. The stringent safety requirements imposed on these foods were a reflection of deep concerns in NASA about the potential consequences of foodborne sickness among astronauts in space, as well as of food particles interfering with flight systems (Stevenson and Bernard, 1995~. Although HACCP made its debut at the 1971 National Conference of Food Protection (Stevenson and Bernard, 1995), analogous systems (not yet designated as HACCP) had been in existence and had been applied in practice in some food-processing operations, notably in the canning of low-acid foods and in milk pasteurization. These operations included: (1) identification and assessment of the hazards: Clostridium botulinum spores in canned low-acid foods and milk-borne pathogens such as Mycobacterium tuberculosis, Brucella spp., and Coxiella burnetii; (2) identification of the critical control point for these hazards: heating at specified temperatures and for similarly specified times in either of these operations; and (3) a system to monitor the critical control point: time and temperature recorders. Despite the fact that these food-processing operations had built-in notions of HACCP, the efforts of the Pillsbury team in articulating the fundamentals of present-day HACCP and testing its effective- ness, followed by additional contributions from the U.S. Army's Natick Labora- tories, are nothing short of landmarks in food safety history. HACCP is well established in the food-processing regulations of the United States. However, its introduction proceeded slowly, beginning in the 1970s and accelerating only until the mid-199Os. The migration of HACCP from textbooks into the U.S. Code of Federal Regulations came about, in part, as a result of a National Academies report (NRC, 1985a) that recommended the adoption of HACCP ". . . universally in food protection programs . . ." and of subsequent, instrumental efforts by the International Commission on Microbiological Specifi- cations for Foods (ICMSF, 1988) and the National Advisory Committee on Microbiological Criteria for Foods (NACMCF, 1998~. Other reports of the National Academies (IOM, 1990, 1991; TOM/NRC, 1998; NRC, 1985a, 1985b) have further endorsed the introduction or expansion of HACCP into the process- ing and inspection of meat, poultry, seafood, and, in general, throughout the food industry. Implementation of HACCP by the food industry has been a slow and at times painful process that still is in progress. To facilitate implementation of HACCP by the food industry and help standardize HACCP training, a coalition of industries and trade organizations in the United States formed the International Meat and Poultry HACCP Alliance in 1994. This group has since endeavored to "train the trainers" by conducting training courses and certifying HACCP trainers who can further train personnel at the processing-plant level. In addition, the

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FOOD SAFETY TOOLS 71 International HACCP Alliance has contributed to the development of generic HACCP plans for use by regulatory agencies in facilitating the preparation of specific HACCP plans by food processors. There is also a Seafood HACCP Alliance and a Juice HACCP Alliance. The committee recognizes the multiple technical, financial, and educational efforts made by the food industry to imple- ment HACCP, including the development and adoption of various interventions to enhance the microbiological safety of the food supply often in anticipation of regulations and commends such efforts. National food safety regulatory agencies and international institutions have published procedures for the development and implementation of HACCP plans. Some of these are established national food regulations, such as those mandated by the Food and Drug Administration (FDA) (21 C.F.R. part 114) and the U.S. Department of Agriculture (USDA) (FSIS, 1996), while others, such as the Codex Alimentarius guidelines on HACCP (CAC, 1997), play a central role in inter- national food trade despite the fact that their adoption by Codex Alimentarius member countries is voluntary. There are numerous HACCP training manuals, including a few that are international in nature (WHO, 1999), as well as a wealth of information on HACCP from various sources. An example of these sources is a joint USDA/ FDA website that offers a variety of training materials (USDA/FDA, 2002~. Continued training in HACCP principles to attain proper implementation by industry personnel and consistent interpretation and monitoring of compliance by inspectors from the regulatory agencies is necessary. The Principles of HACCP Unlike the traditional model for food safety assurance that has been used for decades, HACCP does not rely on end-product testing to ensure the safety of food batches, but on continuous control and monitoring of Critical Control Points (CCPs) along the production and processing continuum. It is, therefore, a preven- tive food safety assurance system in that it focuses on ensuring control of known potential hazards before the product reaches the end of the line, as opposed to the traditional corrective system that focuses on examining the final product and determining whether any hazard of concern is present. CCPs, in general, are defined in HACCP language as "those points where loss of control would result in an unsafe food product," and more specifically as "those points where the identified hazardous) may be prevented from entering the food, eliminated from it, or reduced to acceptable levels" (Stevenson and Bernard, 1995~. It is noteworthy, however, that an intrinsic weakness of HACCP is that it does not provide information on what these acceptable levels are or a guide on how to set them. Linkage between public health goals and HACCP, through a developing concept of Food Safety Objectives (described later in this chapter), may enable regulators in the future to define numerical levels of tolerance for

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72 SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD foodborne hazards in foods at the point of consumption that could be translated into "acceptable levels" at CCPs in food-processing plants. The methodology for developing a HACCP plan calls for the systematic application of seven principles: 1. Hazard analysis 2. Identification of CCPs 3. Establishment of critical control limits for each CCP 4. Establishment of monitoring procedures for each CCP 5. Establishment of corrective actions 6. Establishment of record-keeping procedures 7. Establishment of verification procedures The process begins with the formation of a team that includes plant manage- ment and personnel, as well as individuals who have expertise in foodborne hazards and the particular product and process being used. The team prepares a flow diagram of the production process and physically examines each of its steps in the actual premises where production takes place. Points along the flow dia- gram where the hazard may be prevented, eliminated, or reduced to acceptable levels, and for which a control exists that can be established and monitored, are designated as CCPs. Critical limits are then set for the parameters that can be measured to determine that the control at each CCP is being effectively applied. Monitoring procedures are then established, and corrective actions are predeter- mined to be taken if a loss of control is indicated by a deviation from the critical limits. The HACCP plan, along with records demonstrating that the controls at each CCP have performed successfully and have been continuously monitored during processing, are organized for ease of access by the processor and by inspectors from the regulatory agency charged with ascertaining compliance with the regulations. Finally, internal and external verification procedures are defined to periodically assess the performance of the system and to revise the HACCP plan whenever changes are introduced in the production process that could com- promise the effectiveness of the system. Internal verification procedures may involve such activities as instrument calibration, periodic product testing, and records review, while external verification may involve expert audits and exter- nal product testing. Full compliance with Good Manufacturing Practices (GMPs) and the pre- existence of Standard Operating Procedures for plant sanitation are assumed to be in place when introducing HACCP into a food-processing plant. Therefore, HACCP is not a stand-alone methodology, but part of a larger set of manufactur- ing practices that include these preconditions. In addition, the HACCP plan is specific for each processing plant, processing line, and product manufactured in each line. As a result of discussions held during information-gathering meetings, the committee has been made aware that inappropriate identification of CCPs and

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FOOD SAFETY TOOLS 73 inappropriate HACCP plans have caused problems in complying with HACCP regulations. Similarly, the committee recognizes that inconsistency in the inter- pretation and enforcement of HACCP rules between and within regulatory agencies has hampered a smooth transition to the new food-processing inspection model and monitoring of compliance with HACCP rules. HACCP has revolutionized food safety assurance by bringing about a radical change in the roles of regulators and regulated industries regarding food safety responsibilities, as described in Chapter 1. The committee believes that despite some continued disagreements between these sectors and some widely publi- cized failures of the system notwithstanding the balance of progress in food safety after implementation of HACCP in various sectors of the food industry is decidedly favorable and commendable. The committee, therefore, endorses the recommendations made by previous reports of the National Academies (IOM, 1990, 1991; TOM/NRC, 1998; NRC 1985a, 1985b) and strongly recommends that the regulatory agencies continue to introduce and audit the implementation of HACCP in all sectors of the food industry as appropriate. RISK ASSESSMENT Various techniques have been examined for their potential to provide a sci- entific basis for improving public health and to address emerging foodborne diseases. Risk assessment has surfaced as one key method to embark upon these challenges. The use of quantitative and qualitative risk assessments for biological issues has emerged from the use of quantitative risk assessments for chemical and environmental toxicology (Dourson et al., 2001; IFT, 2002; Neubert, 1999; Paustenbach, 2000~. In simple terms, quantitative risk assessment uses math- ematical equations, numerical data, and expert opinion to create a computer simulation of reality. These computer models allow interested individuals to explore various risk-management options. Quantitative risk assessment is useful because it allows risk managers to see the entire situation related to a hazard without being an expert on each one of the component factors. Risk managers can rapidly examine various technical solutions to a problem using computer-based models, while using their expert judgment on the social, political, and economic factors that also influence how policies are perceived. Risk assessment is usually presented as part of the overall risk analysis paradigm, where risk analysis consists of risk assessment, risk communication, and risk management (Figure 3.1) (dose, 2000~. Quantitative risk assessment is a scientific process that addresses the magnitude of the risk and identifies factors that control it. Risk communication is a social and psychological process that promotes dialogue among different affected individuals regarding the risk. Finally, risk management is a process that combines science, politics, economics, and proper timing to arrive at a decision regarding what to do about the risk.

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74 \ FIGURE 3.1 Components of a risk analysis. SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD - - Risk / \ Risk Management - ~ Assessment Risk Communication - Differences and Similarities Between Chemical and Microbial Risk Assessment Chemical risk assessment is a relatively mature field compared with that of microbial risk assessment. This is due in part to the requirement for drugs and chemicals to be approved or registered by either FDA or the U.S. Environmental Protection Agency (EPA) prior to human exposure. Rigid guidelines have been established and quantitative approaches to assessing adverse effects in humans have been developed. Despite the differences in maturity, the overall paradigm of chemical risk assessment has remarkable similarities to the emerging practice of microbial risk assessment. A comparison of key differences and similarities may benefit both fields. In both fields, risk assessment is a component of the larger field of risk analysis that also encompasses risk management and risk communication. A variety of diagrams have been used to explain the interaction of these compo- nents, including that shown in Figure 3.1. Chemical (and microbial) risk assess- ments are typically divided into four parts: hazard identification, dose-response assessment (or hazard characterization), exposure assessment, and risk character- ization (Lammerding and Paoli, 1997; Neubert, 1999; Paustenbach, 2000~.

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FOOD SAFETY TOOLS Hazard Identification 75 Hazard identification involves assessing whether the agent (chemical or microbial) produces adverse effects in biological systems. Historically, this was assessed for chemicals through the use of animal bioassay screens, but now it is largely accomplished using in vitro systems and, recently, by techniques targeted to advances in genomic sciences. Microbial risk assessments are typically initi- ated in response to a public health concern, and hazard characterization in micro- bial risk assessment typically uses epidemiological or outbreak data (Escherichia cold 0157:H7 Risk Assessment Team, 2001; Salmonella Enteritidis Risk Assess- ment Team, 1998~. The hazard characterization step in microbial risk assessment includes iden- tifying the organism that caused the public health concern and summarizing the details regarding the exposure pathway and the microbial ecology of the particular hazard (see Chapter 2~. Dose-Response Assessment Once an agent is identified as potentially injurious, the next phase is to define the dose-response relationship. The techniques for chemical dose-response assessments are well defined, while the same cannot be said for their microbial counterparts. Studies conducted in laboratory animals form the basis of the field of toxi- cology and are readily used in chemical risk assessment. There is an extensive experimental database of well-designed laboratory animal studies, all conducted under agreed upon Good Laboratory Practice (GLP) guidelines (40 C.F.R. 160.1~. GLP guidelines ensure that all tests conducted for regulatory action on a drug or for chemical registration are conducted according to acceptable practices and generate an auditable paper trail. The validity of this approach to chemical risk assessment has a proven track record: FDA uses essentially these same techniques in preclinical studies of human drugs. The determination of dose for a human drug is based on knowledge of the dose-response relationship for both beneficial and adverse effects. The extensive pro- and postmarketing drug approval process validates the accuracy of these approaches. Tolerances for man-made chemicals introduced into the food supply are based on extrapolation of no-effect data from laboratory animal studies. Experi- ences with FDA drug approval would indirectly support the validity of this approach, as stated above. Microbial risk assessment is qualitatively quite different, for microbial hazards are not man-made and usually are introduced into the food supply only naturally or accidentally. Because of the host-pathogen specificity differences, animal studies are of only limited use in microbial risk assessment. Additionally, no microbial equivalent of the FDA human-drug approval process

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76 SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD exists to validate any proposed dose-response relationships, although if properly collected, outbreak data may help in this regard. Experimental designs in chemical risk assessment are specific for different toxicological endpoints (e.g., acute, subacute, chronic, reproductive, carcino- genic). The mathematical form of the dose-response relationship is assessed based on the biological mechanism of action of the chemical being studied. The end result is a definition of a dose that does not produce adverse effects in laboratory animals: the no-observed-adverse-effect level (NOAEL). There are many variations on how this is determined and on how data from multiple studies are combined (Neubert, 1999~. However, for the purpose of this discussion, the key point is that in chemical risk assessment, the end product (derived from standard toxicological testing protocols) is a defined dose considered safe by the scientific community. Microbial dose-response relationships have been derived from human feed- ing trials (many done on volunteer prisoners in the early part of the twentieth century), animal studies, and, increasingly, data from foodborne disease out- breaks, as noted. As with chemical risk assessment, various endpoints can be used, ranging from mild diarrhea to death; also, data from multiple studies can be combined (Holcomb et al., 1999~. A variety of mathematical forms for microbial dose-response has been proposed. Microbial dose-response equations do not have as clear a link to a biological mechanism as in chemical risk assessment, due in part to the complexity of the underlying biology. The committee believes that defining microbial dose-response relationships for foodborne pathogens is important if more accurate risk assessment results are desired. Allocation of resources to fund basic research studies defining these relationships would help to remedy this deficiency. The host side of the dose-response relationship may also be different for microbial and chemical risk assessments. Some researchers have suggested that in the case of microbial risk assessment, a population's response to an infectious pathogen is more variable than it is to acutely toxic chemicals and rivals the complexity seen with carcinogens. This variability is due to altering immune status as a function of genetics, environment, age, concurrent diseases, and a host of other factors (ICMSF, 1998~. However, the response of an individual to a chemical exposure is also variable based on many of the same factors and indi- vidual differences in the inherent receptor sensitivity, pharmacokinetics (includ- ing metabolism), and simultaneous exposure to a myriad of drugs and chemicals. In both scenarios, the large degree of interindividual variability makes the risk assessment process prone to large degrees of uncertainty. In the drug arena, the development of population pharmacokinetic tech- niques has partially reduced this uncertainty by identifying subpopulations that vary significantly from the norm. Perhaps the most important difference is that microbial dose-response assessment for infectious pathogens does not produce any concept analogous to the NOAEL, since a single microbial cell may (under

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FOOD SAFETY TOOLS 77 the right circumstances) produce illness. It may, however, be possible to use a risk assessment term analogous to the NOAEL for organisms like Staphylococ- cus aureus or Bacillus cereus that cause illness through formation of a toxin in the food, or for Listeria monocytogenes in healthy adults. Because microbial dose-response assessment does not typically produce a NOAEL, the key point in microbial risk assessment is that for many pathogens there is no safe dose. Even if a microbial NOAEL could be determined, it might not be adopted. USDA's Food Safety and Inspection Service (FSIS) has taken the position with respect to Escherichia cold 0157:H7 that it is an adulterant, and hence, it is not allowed in raw ground beef in any number (see Chapter 4~. While the agency could change its position in this regard, it might be difficult to explain such a change to the public, and so it might hesitate to do so. If a firm scientific basis for determining no-effect levels for some pathogens existed, along with appropriate detection and enumeration methods to ensure that microbial NOAELs are not exceeded, it would still be necessary to convince the public that their safety would be suffi- ciently assured by the implementation of the microbial NOAELs. Exposure Assessment The next step in either microbial or chemical risk assessment is to estimate human exposure to the agent. For chemicals such as pesticides, environmental compounds, and food additives, potential modes of exposure must be assessed. These include assessing whether the primary routes are inhalation, dermal, or, in the case of food chemicals or microorganisms, oral. Aggregate exposure must be determined where multiple routes may contribute to human exposure. This often occurs in the case of pesticides, where exposure may occur by inhalation after spraying in a home or place of work, orally in food, or dermally by physical contact with a sprayed surface. For chemicals, a major task of exposure assess- ment is to determine the fraction of the dose that is actually absorbed into the body, that is, the bioavailability. Additionally, it is important to determine if this absorbed dose is metabolized, either to an inactive moiety or to an active and potentially toxic metabolite. An arena where risk assessment is routinely applied to chemicals is in the drug approval process. Pharmaceutical drugs are somewhat different in this respect than other chemicals because hazard characterizations and dose-response assessments are conducted in the preclinical phases of drug development in order to estimate a tolerable dose for humans. Hazard identifications for pharmaceuti- cals are essentially validated in the first phase of human testing. The appropriate dose is finally determined after the second and third phases of human testing, which seek to determine effectiveness and obtain additional safety information. When the drug's sponsor applies to FDA for approval of its application to market the drug, a determination is made on whether it is safe and effective and may be released to the marketplace. The approval process necessitates balancing the

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78 SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD potential benefits of the drug to the patient population against the risks that it might pose. Through the initial testing or postmarket surveillance, information may arise that suggests that certain specific patient populations are more at risk than others for adverse effects or treatment failures; such information may be reflected in labeling information that guides proper drug use. If information is developed later that changes the risk/benefit ratio significantly, FDA may require that the drug be withdrawn from the market. Exposure assessment in quantitative microbial risk assessment (QMRA) involves modeling movement of the pathogen through the production system. Both temporal (in time) and spatial (in space) exposure data are relevant to this step. Exposure assessment results in an estimate of the likelihood of pathogen ingestion by the consumer. Exposure assessment for microorganisms is quite different from that for drugs or other chemicals, primarily because (at least with bacterial pathogens) some microorganisms can increase or decrease in number in the food under suitable conditions. Aggregate exposure to multiple chemicals is often consid- ered, especially with carcinogens. Although each chemical exposure to an indi- vidual in a given time period might not produce illness, such exposures may produce subclinical organ damage, induce metabolic changes, or result in accu- mulation that could modify subsequent responses. In contrast, if repetitive expo- sure to low levels of infectious microbes occurs, host immunity may decrease risk (ICMSF, 1998), but counterexamples also exist (Maijala et al., 2001~. Unlike a chemical that has a constant potency (unless degraded), a microbe is dynamic and adaptable. Virulence factors acquired from other organisms could change the inherent infectivity and pathogenicity of a foodborne microorganism (ICMSF, 1998~. In food-processing operations that combine raw materials from multiple sources, microbial or chemical contamination in some of these raw materials would have differing effects on contamination in the resulting product. While a chemical contaminant would be diluted during mixing, similar dilution of bacte- rial contaminants would mean that the bacteria are spread throughout the mix (e.g., by breakup of microbial colonies that initially may be highly localized into what is referred to as "point source" or "hot spots" in the incoming raw material). For example, consider the mixing of meat trimmings in a grinding operation where a point source of either a chemical or a bacterial pathogen occurs. Dilution of the chemical from a point source to a larger mass of product would be expected to reduce the hazard by decreasing the concentration of the chemical a consumer would ingest. In the case of bacteria, mixing meat trimmings from multiple sources (animals, producers, packing plants, states, countries) would increase the volume of contaminated ground product and, because of bacterial growth, the potential number of consumers that might be affected. The spread of bacterial contaminants would also seriously confound attempts to trace back the source of contamination to a specific supplier of raw material.

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FOOD SAFETY TOOLS 79 This effect is well known in the dairy industry, where milk that contains antibiotic residues from an individual cow will be diluted in the tank truck after mixing with milk containing no antibiotic residues. Thus, because of similar dilution effects, ground-meat products would be expected to raise no major concerns regarding chemical residues; but, unlike the situation in whole-muscle meat, chemical hot spots would likely be spread in ground meat. Therefore, the microbiological risk in ground meat may be expected to be greater than any chemical risk. The same logic could be extended to processing food from multiple sources or to consump- tion of a contaminated item in a multi-ingredient meal (e.g., vegetables, meat, and sauces). There are also some differences in the analytical detection of microbes versus chemicals that may impact data used in exposure assessment calculations. Concerns about sampling strategies are fairly similar for both chemicals and microbes, although the latter may be more prone to localization from hotspots of point- source microbial contamination. In the chemical residue arena, the development of multiple drug-class residue screening assays that would detect and quantify multiple contaminants in a single assay has been the focus of recent research efforts. Once considered cost prohibi- tive, these techniques are based on gas chromatography/mass spectrometry and are now feasible. Similar developments have begun to occur in the microbiological arena (see Chapter 1~. A similarity between chemicals and microbial pathogens is that all chemicals and pathogens do not have, qualitatively or quantitatively, the same propensity for causing human illness. Chemicals may exert a number of different types of toxicological reactions, including allergenicity, immunotoxicity, mutagenicity, carcinogenicity, and "classic" chemical toxicity (renal, hepatic, etc.) seen with many pesticides and drugs. A single chemical may exhibit the full spectrum of effects depending on the dose and length of exposure. Quantitative structure- activity relationships have also been developed that help in the prediction of these chemical effects. For microbes, a similar diverse spectrum of potential adverse effects can be observed depending on the species, serotype, strain, or host differ- ences. For example, ingestion of foods contaminated with some strains of E. cold may produce a transient gastrointestinal disturbance, while exposure to strains such as 0157:H7 may be fatal for some individuals. Finally, detection of a chemical allows one to estimate whether the sample exceeds tolerance. Tech- niques such as polymerase chain reaction (PCR), which amplifies deoxyribo- nucleic acid (DNA), can detect and in some cases can also quantify patho- gens (Hein et al., 2001a, 2001b; Li and Drake, 2001~. However, rapid tests that determine microbial viability and infectivity are just becoming available (see Chapter 1~. The issue of multiple points of contamination within a food-processing estab- lishment is also different for some chemical classes versus microorganisms because of the ability of some of the latter (e.g., bacteria, molds) to multiply and

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SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD \ Marginal social benefit Marginal social cost / I. #~d i.. - id i.. - id i.. - ad i.. - ~ I Higher level of safety ~ 00/0 FIGURE 3.4 Toward a public health goal: relating an appropriate level of protection (ALOP) to marginal social benefit and cost. benefits coincide (Figure 3.4~. (As stated above, it is unlikely that definitive values can be provided of costs and benefits, and therefore such curves convey the most likely values around which confidence intervals must be built.) The inability of consumers to fully identify a product level of safety compared with the greater knowledge that processors have of the ability of a process to deliver safety (termed "imperfect and asymmetric" information problems in the litera- ture) suggests that the market will fall short in providing the socially optimal level of protection for the particular product or pathogen under review. Economic efficiency requires that the ALOP to aim for be at the point where marginal social costs equal marginal social benefits (Figure 3.4~. Away from this equilibrium, either society desires a safer product and would benefit more than the additional costs of the stricter regime (points to the left of ALOP), or society is expending too many resources compared with the additional safety gains real- ized (to the right of ALOP). The ALOP can be related to the particular public health goal of the regulator because the model is stated in dollar terms but is partially based on population measures (benefit estimates). It is important to note that marginal social costs and marginal social benefits may change given the form of a regulation, the particular population and food product under assess-

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FOOD SAFETY TOOLS 123 meet, and, over time, with a change in available technology or changing con- sumer demands or consumption patterns. Therefore, the ALOP and the most efficient food safety criteria are likely to be dynamic, given changing consumer tastes and preferences, risk tolerances, industry capabilities, and government oversight functions. An example of how such marginal social costs can be calculated, highlight- ing costs to companies from the adoption of particular food safety strategies, is shown in Figure 3.5. Four possible strategies or combinations of efforts having various levels of effectiveness and cost are shown. Various interventions (single- or multiple-hurdle strategies) can be assessed based on their cost of implementa- tion (possibly reported for various sizes or types of plants) and the most likely effectiveness (e.g., ability of the process to reduce the presence of a particular pathogen by x logic) and, therefore, on their ability to attain a performance standard (S) with a certain probability. Similarly, if S were a food safety objec- tive, then the technique could be used to assess sets of interventions adopted by various companies throughout the supply chain. The horizontal line in Figure 3.5 indicates points associated with the concept that multiple strategies may meet the necessary effectiveness (S) but with different varying costs. Effectiveness __ _c B _- C ma_ ~- c1 Cost FIGURE 3.5 Relationship between the effectiveness (i.e., pathogen reduction) and cost of hypothetical food safety strategies available to food-processing companies. SOURCE: Jensen et al. (1998), Markarian et al. (2001~.

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24 SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD Strategies such as point D (Figure 3.5) are dominated by each of the other options (A, B. and C) in the figure; these other options have either lower cost (like point A) or higher effectiveness (points B and C), or both. The curved line passing through points A, B. and C links all of the most favorable strategies and therefore provides an optimal path of technical food safety effectiveness. The area to the right of the curved line also suggests that there are marginal costs for various levels of food safety (for example, consider moving from point B to C). The standard S in Figure 3.5 will result in a cost of at least Cat based on where the optimal curved line and horizontal line intersect. Technical effectiveness (the frontier) is dynamic; innovations shift the curve up, allowing enhanced effectiveness for the same cost. Process criteria essentially dictate the particular strategy that must be followed by the industry (for example, strategy at point D). However, this may not result in the lowest cost (compare A with D). Furthermore, process criteria likely prevent the selection of more effective interventions (like B or C). The strategies that meet (and in this case exceed) standard S are both B and C. The particular intervention that would be selected by industry is less clear when facing a performance standard (which is considered more flexible, since many options to meet the standard may be available) as opposed to process criteria. This situation illustrates the difficulty in forecasting costs in response to a performance standard. Certain companies may decide to exceed the standard by a long measure, while others may choose to meet the standard and no more. Resulting from these different decisions, an array of potential costs can be estab- lished creating a large range (with a well-defined lower bound Car, Figure 3.5) of estimates for the related economic impact assessment of performance standards. This wide range of impact-assessment estimates would also be related to a broad range for the marginal social cost estimate (recall the marginal social cost curve in Figure 3.4), with the lower bound relating to the minimal cost (C~ in Fig- ure 3.5) of achieving standard S. This illustrates the difficulty of performing economic impact assessments. Because of the complicated situation presented above, the committee con- cluded that uncertainty still exists with respect to the economics of food safety regulations. The following are examples of questions that need to be answered: Has the correct balance of incentives to innovate, benefits, and costs been achieved? From an economic standpoint, are performance standards or process criteria better for food safety? Which economic sector benefits most from perfor- mance standards? What about performance criteria? In economic terms, what are the consumer, government, and industry responses to performance standards and performance criteria? Traditional economics suggest that performance standards should lead to a no-higher set of industry (company) costs, yet performance standards may cause the government sector to incur additional costs. Therefore, the specifics of a particular performance standard should be assessed to deter- mine this balance. Further research in these areas is required to better answer the questions above and similar ones not yet raised.

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FOOD SAFETY TOOLS 125 THE IMPACT OF CHANGING TECHNOLOGY: NEW DIAGNOSTIC TOOLS Any regulatory system is heavily dependent on the technology available to detect deviations from regulatory performance standards. For that matter, the performance standards themselves may be influenced by available diagnostics, with the requirement for nondetectable levels as established by regulations having less meaning when it is possible to detect problems (such as the presence of specific pathogens) with a 10-, 100-, or 1,000-fold increase in sensitivity. Current regulatory standards for foodborne pathogens, in almost all instances, assume use of traditional culture techniques to determine the presence and number of pathogens or indicator organisms in a product. However, culture techniques tend to be slow, with two or three days often required for initial isolation of a microorganism, followed in many instances by several days of additional testing to confirm that the microorganism isolated is indeed pathogenic or that it carries the necessary virulence genes to represent a hazard to humans. There has been increasing movement toward the use of immunological assays in diagnostics which, when combined with traditional culture techniques, can provide results in less time and with greater accuracy. However, it is genetic techniques that have the greatest potential for revolutionizing these more traditional approaches. There is now increasing experience with PCR, and PCR and probe-based methods are being used with increasing frequency. Examples in work with seafood include the use of DNA probes for V. vulnificus (Wright et al., 1996) and pathogenic (tdh-, trh-, or tlh-containing) strains of V. parahaemolyticus (DePaola et al., 2000), and use of PCR assays for the tdh gene in assessing possible virulence of clinical and environmental V. parahaemolyticus strains (Young et al., 2002~. Further rapid advances in molecular diagnostics may be anticipated, includ- ing the development of some microarray assays for pathogenic microorganisms. Microarrays, as currently formulated, are multiple assay arrays on glass slides on which hundreds or thousands of probes are spotted, permitting a test sample to be screened against all probes simultaneously. Currently, the most common applica- tion of microarrays is to measure the presence and quantity of up to 20,000 messenger ribonucleic acid (mRNA) transcripts from mammalian cells (Schena et al., 1996~. However, genomic microarrays to distinguish among species of bacteria using the 16S ribosomal RNA gene have also been reported (Bavykin, 2001), with each probe on the microarray selected to identify a species of bacteria. In addition, microarrays have been used to identify genes lost between different strains of E. cold (Ochman and Jones, 2000), Helicobacter (Salama et al., 2000) and Staphylococcus (Fitzgerald et al., 2001~. With microarrays it is theoretically possible to immediately and quantitatively identify many, if not all, potential pathogens in a sample; to identify strains carrying specific virulence genes or strain subsets that have been linked with increased transmission potential (i.e., superclones); and to identify other genes of interest, including resistance genes.

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26 SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD While such microarray systems are not currently available commercially, they represent a very promising technology for food safety applications. The rapid advances being seen in this field of diagnostic technology under- score the need for flexibility in any regulatory approach or development of per- formance standards. This includes a need for flexibility at several levels. Currently, there is a perception on the part of regulatory agencies that iden- tification of a pathogen for regulatory purposes is not "real" unless a micro- organism is isolated. Regulations need to be changed to recognize that molecular and other rapid methods can produce results of comparable or greater accuracy than those obtained with traditional culture techniques; there must be provisions in regulatory actions for the use of data obtained with such methods. Any regulatory approaches, including the establishment of performance stan- dards, must have built into them sufficient flexibility to take advantage of the improvements in diagnostics that will almost certainly occur. THE LIMITS OF SCIENCE Some portion of the public surely is skeptical about most scientific pro- nouncements because of the seemingly conflicting advice, over time, from studies conducted in areas such as nutrition and health. However, the committee recog- nizes that many people believe that science and technology, given time and money, can fix everything. While this expectation may not hold for vexing problems deemed to be natural in origin (e.g., in respect to diseases such as cancer and acquired immune deficiency syndrome), man-made problems seem amenable to man-made solutions. Pathogens in store-bought foods are likely perceived by many as a man-made problem (e.g., E. cold in juices). When the committee held an open meeting to hear testimony from families that had suffered tragic losses from foodborne illness, the speakers (on the record as well as in private pleas in hallways after the session) urged committee members to "do something" to prevent others from suffering as they had. Eminent scientists, it was their heartfelt belief, could solve the problem. Scientists and engineers have developed skills and made discoveries that do enable the solutions to numerous problems of human origin. One example is the carnage done over the years because of vehicle accidents. Technological and legal changes that have made cars and their passengers safer have reduced the vehicular death and disability toll. While increased enforcement could further reduce the problem, this toll could be dramatically reduced through technology by designing all vehicles much like military tanks, but such a drastic step would dramatically increase the costs of vehicular travel and, through greater fuel needs, their environmental impact. Even where science and technology have solutions, their costs may be greater than society is willing to pay to achieve the projected benefits. In these cases, society must determine the trade-off between costs and benefits by tackling the question: What is the optimum level of safety we should

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FOOD SAFETY TOOLS 127 seek to achieve? To pick an extreme example, it soon will be possible to test food for all pathogens and toxins of concern; all food could, in theory, be sampled prior to consumption. Such a system would of course be entirely impractical, both financially and logistically, although it would make the food almost thoroughly safe for the consumer. For our society, ensuring food safety is certainly an important goal that has not yet been adequately achieved. Policymakers who wish to improve the food safety system need to ensure adequate government financial resources for the creation and enforcement of safety rules. Food safety requirements imposed upon the food industry have financial consequences that may result in higher food prices. For example, significant changes could be made in animal husbandry and slaughter practices that would reduce the level of pathogens in food sold to the public. Science might be able to discover better, less expensive means to deal with pathogens in the food supply. Vaccines might be created that prevent food animals from being colonized by pathogens that, while harmless to the animals, are a danger to people. Simple, safe methods to kill pathogens on produce might be developed. Some scientific advances that their proponents claim will lead to a net benefit in food safety such as food irradiation and changes involving genetic modification are opposed by some members of the public because of concerns that one set of risks is being exchanged for another, to the frustration of many in the scientific community (Henderson, 2002~. Although there are limits to what science can achieve in consumer protec- tion, a more significant limit in the food safety system may well be the willing- ness of the public to accept the costs of implementing the measures that are available. Given the high costs to our society of morbidity and mortality that are related to foodborne illness, it would be sensible to require investment in food safety that yields a positive return. That is, to the extent that expenditures to improve food safety overall exceed the costs of the harm, these expenditures should definitely be made (and prices allowed to rise to cover the extra costs). Making such changes might interfere with consumer expectations about the low- cost availability of food. Some of the least-expensive interventions (such as hand washing by food handlers and improving retail worker and consumer compliance with safe food handling and cooking guidelines) are the most difficult to attain because they necessitate changing behaviors of vast numbers of people. How- ever, while everyone must purchase food and eat (and thus everyone has an interest in keeping down the cost of food), the harm from serious foodborne illness falls on a small fraction of the population. Are the many willing to devote resources to prevent serious harm to the few? Those who have lost loved ones (many of whom have been young children) to foodborne illness answer this question loudly in the affirmative; others are far less certain. While science and technology will continue to search for and discover answers to problems involv- ing foodborne illness, inexpensive answers are often unavailable or impractical. Where to draw the line between requirements that should be implemented and

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28 SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD that are reasonably cost-effective, and those that would be beneficial but would have too great an impact on food pnces, is a question for politics rather than for science. REFERENCES ASTM (American Society for Testing and Materials). 1976. Manual on Presentation of Data and Control Chart Analysis Committee E on Quality and Statistics. ASTM MNL7. Philadelphia: ASTM. Bavykin SO, Akowski JP, Zakhariev VM, Barsky VE, Perov AN, Mirzabekov AD. 2001. Portable system for microbial sample preparation and oligonucleotide microarray analysis. Appl Environ Microbiol 67:922-928. Bothe DR. 2001. Measuring Process Capability. Cedarburg, WI: Landmark Publishing. Breyfogle FW, Cupello JM, Meadows B. 2001. Managing Six Sigma: A Practical Guide to Under- standing, Assessing and Implementing the Strategy that Yields Bottom-Line Success. New York: John Wiley & Sons. Busta F. 2002. Application of Science to Food Safety Management. Presentation to the Institute of Medicine/National Research Council Committee on the Review of the Use of Scientific Criteria and Performance Standards for Safe Food, Washington, DC, April 3. CAC (Codex Alimentarius Commission). 1997. Hazard Analysis and Critical Control Point System and Guidelines for its Application. Annex to CAC/RCP 1-1969, Rev. 3-1997. Rome: Food and Agriculture Organization of the United Nations. Cassin MH, Lammerding AM, Todd ECD, Ross W. McColl S. 1998. Quantitative risk assessment of Escherichia cold 0157:H7 in ground beef hamburgers. Int J Food Microbiol 41 :21-44. CFSAN/FSIS/CDC (Center for Food Safety and Applied Nutrition/Food Safety and Inspection Service/Centers for Disease Control and Prevention). 2001. Draft Assessment of the Relative Risk to Public Health from Foodborne Listeria monocytogenes among Selected Categories of Ready-to-Eat Foods. Online. Food and Drug Administration (FDA), U.S. Department of Agri- culture (USDA). Available at http://www.cfsan.fda.gov/~dms/lmrisk.html. Accessed May 8, 2003. Cianfrani CA, Tsiakals JJ, West JE. 2002. The ASQ ISO 9000:2000 Handbook. Milwaukee: ASQ Quality Press. COST Action 920. 2000. Foodborne Zoonosis: A Co-ordinated Food Chain Approach. Online. Available at http://www.cost920.com. Accessed December 12, 2002. CVM (Center for Veterinary Medicine). 2001. The Human Health Impact of Fluoroquinolone Resis- tant Campylobacter Attributed to the Consumption of Chicken. Online. FDA. Available at http:/ /www.fda.gov/cvm/antimicrobial/revisedRA.pdf. Accessed August 1, 2002. DePaola A, Kaysner CA, Bowers J. Cook DW. 2000. Environmental investigation of Vibrio parahaemolyticus in oysters after outbreaks in Washington, Texas, and New York (1997 and 1998). Appl Environ Microbiol 66:4649-4654. Dourson ML, Andersen ME, Erdreich LS, MacGregor JA. 2001. Using human data to protect public health. Reg Toxicol Pharmacol 33:234-256. Escherichia cold O 157:H7 Risk Assessment Team. 2001. Draft Risk Assessment of the Public Health Impact of Escherichia cold 0157:H7 in Ground Beef. Online. FSIS, USDA. Available at http:// www.fsis.usda.gov/OPPDE/rdad/FRPubs/00-023N/00-023NReport.pdf. Accessed September 12, 2001. FAD/WHO (Food and Agriculture Organization of the United Nations/World Health Organization). 2000. Hazard Characterization, Exposure Assessment of Listeria monocytogenes in Ready-to- Eat Foods (RTE). Joint FAD/WHO Expert Consultation on Risk Assessment of Microbiological Hazards in Foods. Rome: FAO

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FOOD SAFETY TOOLS 129 FAD/WHO. 2001. Hazard Identification, Exposure Assessment, and Hazard Characterization of Campylobacter spp. in Broiler Chickens and Vibrio spp. in Seafood. Joint FAD/WHO Expert Consultation on Risk Assessment of Microbiological Hazards in Foods. Geneva: WHO. FDA. 1999a. Food labeling: Safe handling statements: Labeling of shell eggs; Shell eggs: Refrigera- tion of shell eggs held for retail distribution; Proposed rule. Fed Regist 64:36491-36516. FDA. l999b. Grade "A" Pasteurized Milk Ordinance. 1999 Revision. Online. Available at http:// www.cfsan.fda.gov/~acrobat/pmo99-l.pdf. Accessed July 19, 2002. FDA. 2001. Hazard Analysis and Critical Control Point (HAACP); Procedures for the safe and sanitary processing and importing of juice; Final rule. Fed Regist 66:6137-6202. FDA. 2002. FDA Food Code. Online. Available at http://www.cfsan.fda.gov/~dms/foodcode.html. Accessed December 12, 2002. FDA/FSIS. 2001. Relative risk to public health from foodborne Listeria monocytogenes among selected categories of ready-to-eat food risk assessment document and risk management action plan. Fed Regist 66:5515-5517. Fitzgerald JR, Sturdevant DE, Mackie SM, Gill SR, Musser JM. 2001. Evolutionary genomics of Staphylococcus aureus: Insights into the origin of methicillin-resistant strains and the toxic shock syndrome epidemic. Proc Natl Acad Sci USA 98:8821-8826. FSIS. 1996. Pathogen reduction; hazard analysis and critical control point (HACCP) systems; Final rule. Fed Regist 61: 38805-38855. FSIS. 1998. Lethality and Stabilization Performance Standards for Certain Meat and Poultry Prod- ucts: Technical Paper. Online. USDA. Available at http://www.fsis.usda.gov/oa/haccp/ lethality.pdf. Accessed August 1, 2002. FSIS. 1999. 1999 National Residue Program: Residue Data. Online. USDA. Available at http:// www.fsis.usda.gov/OPHS/red99/intro.pdf. Accessed August 1, 2002. FSIS. 2001. HACCP-Based Inspection Models Project (HIMP): Young Chicken Inspection. Online. USDA. Available at http://www.fsis.usda.gov/OPPDE/Nis/HIMP/Docs/YNGChk_Drf6.pdf. Accessed July 19, 2002. Gallagher DL, Ebel ED, Kause JR. 2003. Draft FSIS Risk Assessment for Listeria in Ready-to-eat Meat and Poultry Products. Online. FSIS, USDA. Available at http://www.fsis.usda.gov/OPHS/ lmrisk/DraftLm22603.pdf. Accessed May 5, 2003. Garthright WE, Chirtel S. Graves Q. 2002. Derivation of Sampling Plan to Meet the Testing Require- ment in the Juice HACCP Final Rule for Citrus Juices that Rely Solely or in Part on Surface Treatments to Achieve the 5-Log Reduction Standard. Washington, DC: Office of Plant, Dairy Food and Beverages, CFSAN, FDA. Gavin A, Weddig L. 1995. Canned Foods: Principles of Thermal Process and Control, Acidifica- tion, and Container Closure Evaluation, 6th ed. Washington, DC: Food Processors Institute. Golan E. 2002. Performance Standards and the Economics of Compliance and Innovation. Presented at the USDA Symposium on Pathogen Reduction A Scientific Dialogue, Economic Research Service, USDA. Washington, DC, May 6. Hein I, Klein D, Lehner A, Bubert A, Brandl E, Wagner M. 2001a. Detection and quantification of the iap gene of Listeria monocytogenes and Listeria innocua by a new real-time quantitative PCR assay. Res Microbiol 152:37-46. Hein I, Lehner A, Rieck P. Klein K, Brandl E, Wagner M. 200 lb. Comparison of different approaches to quantify Staphylococcus aureus cells by real-time quantitative PCR and application of this technique for examination of cheese. Appl Environ Microbiol 67:3122-3126. Henderson M. 2002, September 9. Public "must allow scientists to take risks." Online. The Times (London). Available at http://www.timesonline.co.uk/article/0,,2-408587,00.html. Accessed October 10, 2002. Holcomb DL, Smith MA, Ware GO, Hung YC, Brackett RE, Doyle MP. 1999. Comparison of six dose-response models for use with food-borne pathogens. Risk Analysis 19:1091-1100.

OCR for page 69
30 SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD ICMSF (International Commission on Microbiological Specifications for Foods). 1988. Microorgan- isms in Foods 4. Application of the Hazard Analysis Critical Control Point (HA CCP) System to Ensure Microbiological Safety and Quality. Oxford: Blackwell Scientific Publications. ICMSF. 1998. Potential application of risk assessment techniques to microbiological issues related to international trade in food and food products. J Food Prot 61:1075-1086. ICMSF. 2002. Microorganisms in Foods 7. Microbiological Testing in Food Safety Management. New York: Kluwer Academic/Plenum Publishers. IFT (Institute of Food Technologists). 2002. IFT Expert Report on Emerging Microbiological Food Safety Issues: Implications for Control in the 21st Century. Chicago: IFT. IOM (Institute of Medicine). 1990. Cattle Inspection. Washington, DC: National Academy Press. IOM. 1991. Seafood Safety. Washington, DC: National Academy Press. IOM. 2002. Escherichia cold 0157:H7 in Beef. Review of a Draft Risk Assessment. Washington DC: National Academy Press. IOM/NRC (National Research Council). 1998. Ensuring Safe Foodfrom Production to Consumption. Washington, DC: National Academy Press. Jensen HH, Unnevehr LJ, Gomez MI. 1998. Costs of improving food safety in the meat sector. J Agric Appl Econ 30:83-94. Kane VE. 1989. Defect Prevention: Use of Simple Statistical Tool. Milwaukee, WI: ASQ Quality Press. Karel M, Fennema OR, Lund DB. 1975. Physical Principles of Food Preservation. New York: Marcel Dekker. Ketola J. Roberts K. 2001. ISO 9001:2000 Management Responsibility in a Nutshell. Milwaukee, WI: ASQ Quality Press. Konz S. Perterson G. Joshi A. 1981. Reducing inspection errors. Quality Progress 14:24-27. Kroes R. Kozianowski G. 2002. Threshold of toxicological concern (TTC) in food safety assessment. Toxicol Let 127:43-46. Kuchler F. Golan E. 1999. Assigning Values to Life: Comparing Methods for Valuing Health Risks. Agricultural Economics Report No. 784. Washington, DC: Economic Research Service, USDA. Kume H. 1985. Statistical Methods for Quality Improvement. Tokyo: The Association for Overseas Technical Scholarship. Lammerding AM, Paoli GM. 1997. Quantitative risk assessment: An emerging tool for emerging foodborne pathogens. Emerg Infect Dis 3:483-487. Law AM, Kelton WD. 2000. Simulation Modeling and Analysis, 3rd ed. Boston: McGraw-Hill. Li WL, Drake MA. 2001. Development of a quantitative competitive PCR assay for detection and quantification of Escherichia cold 0157:H7 cells. Appl Environ Microbiol 67:3291-3294. LSRO (Life Sciences Research Office). 1995. Third Report on Nutrition Monitoring in the United States, Appendix III. Washington, DC: U.S. Government Printing Office. MacDonald JM, Crutchfield S. 1996. Modeling the costs of food safety regulation. Am JAgric Econ 78: 1285-1290. Maijala R. Lyytikainen O. Johansson T. Autio T. Aalto T. Haavisto L, Honkanen-Buzalski T. 2001. Exposure of Listeria monocytogenes within an epidemic caused by butter in Finland. Int J Food Microbiol 70:97-109. Markarian V, Hooker NH, Murano EA, Acuff GR, Carroll S. 2001. Comparative costs of pathogen reduction strategies for Australian beef slaughter plants. In: Hooker NH, Murano EA, eds. Interdisciplinary Food Safety Research. Boca Raton, FL: CRC Press. Pp. 25-41. Montgomery DC. 2001. Introduction to Statistical Quality Control, 4th ed. New York: John Wiley & Sons. NACMCF (National Advisory Committee on Microbiological Criteria for Foods). 1997. Recommen- dations on Fresh Juice. Online. FDA. Available at http://cfsan.fad.gov/~mow/nacmcf.html. Accessed January 23, 2003.

OCR for page 69
FOOD SAFETY TOOLS 131 NACMCF. 1998. Hazard analysis and critical control point principles and application guidelines. J Food Prot 61:1246-1259. Neubert D. 1999. Risk assessment and preventative hazard minimization. In: Marquardt H. Schafer SS, McClellan RO, Welsch F. eds. Toxicology. New York: Academic Press. Pp. 1153-1190. NRC (National Research Council). 1985a. An Evaluation of the Role of Microbiological Criteria for Foods and Food Ingredients. Washington, DC: National Academy Press. NRC. 1985b. Meat and Poultry Inspection: The Scientific Basis of the Nation's Program. Washing- ton, DC: National Academy Press. Ochman H. Jones IB. 2000. Evolutionary dynamics of full genome content in Escherichia colt. EMBO J 19:6637-6643. Paige JC, Pell F. 1997. Drug residues in food-producing animals. Online. FDA Veterinarian News- letter. Available at http://www.fda.gov/cvm/index/fdavet/1997/july.htm#res. Accessed April 11, 2003. Paustenbach DJ. 2000. The practice of exposure assessment: A state-of-the-art review. J Toxicol Environ Health 3: 179-291. Porter ME, van der Linde C. 1995. Green and competitive: Ending the stalemate. Harv Bus Rev 73: 120-134. Posnick L, Burr D, Bowers J. Walderhaug M, Miliotis M. 2001. Draft Risk Assessment on the Public Health Impact of Vibrio parahaemolyticus in Raw Molluscan Shellfish. Online. CFSAN, FDA. Available at http://www.cfsan.fda.gov/~dms/vprisksu.htm. Accessed August 1, 2002. President's Council on Food Safety. 1999. Egg Safety from Production to Consumption: An Action Plan to Eliminate Salmonella Enteritidis Illnesses Due to Eggs. Online. Available at http:// www.foodsafety.gov/~fsg/ceggs.htm. Accessed July 19, 2002. Rose JB, Haas CN, Regli S. 1991. Risk assessment and control of waterborne giardiasis. Am J Public Health 81 :709-713. RTI (Research Triangle Institute). 2000. HACCP-Based Inspection Models Project: Baseline Results for Young Chickens. Online. FSIS, USDA. Available at http://www.fsis.usda.gov/oa/haccp/ base_broilers.pdf. Accessed January 13, 2002. Salama N. Guillemin K, McDaniel TK, Sherlock G. Tompkins L, Falkow S. 2000. A whole-genome microarray reveals genetic diversity among Helicobacter pylori strains. Proc Natl Acad Sci USA 97:14668-14673. Salmonella Enteritidis Risk Assessment Team. 1998. Salmonella Enteritidis Risk Assessment: Shell Eggs and Egg Products. Online. FSIS, USDA. Available at http://www.fsis.usda.gov/OPHS/ risk/index.htm. Accessed August 1, 2002. Schena M, Shalon D, Heller R. Chai A, Brown PO, Davis RW. 1996. Parallel human genome analysis: Microarray-based expression monitoring of 1000 genes. Proc Natl Acad Sci USA 93: 10614-10619. Singer DL. 2001. A Laboratory Quality Handbook of Best Practices and Relevant Regulations. Milwaukee, WI: ASQ Quality Press. Steel RGD, Torrey JH, Dickey DA. 1997. Principles and Procedures of Statistics: A Biometrical Approach, 3rd ed. New York: McGraw-Hill. Stevenson KE, Bernard DT, eds. 1995. HACCP. Establishing Hazard Analysis Critical Control Point Programs. A Workshop Manual, 2nd ed. Washington, DC: Food Processors Institute. Taylor M. 2002. Microbiological Performance Standards for Food Safety. Presentation to the Insti- tute of Medicine/National Research Council Committee on the Review of the Use of Scientific Criteria and Performance Standards for Safe Food, Washington, DC, April 3. USDA/FDA. 2002. HACCP Training Programs. Online. National Agricultural Library. Available at http://www.nal.usda.gov/foodborne/haccp/training.html. Accessed October 16, 2002. Vose D. 2000. Risk Analysis: A Quantitative Guide, 2nd ed. New York: John Wiley & Sons. Wheeler DJ, Chambers DS. 1992. Understanding Statistical Process Control, 2nd ed. Knoxville, TN: SPC Press.

OCR for page 69
32 SCIENTIFIC CRITERIA TO ENSURE SAFE FOOD Whiting RC, Buchanan RL. 1997a. Development of a quantitative risk assessment model for Salmo- nella Enteritidis in pasteurized liquid eggs. Int J. Food Microbiol 36:111-125. Whiting RC, Buchanan RL. 1997b. Predictive modeling. In: Doyle MP, Beuchat LR, Montville TJ, eds. Food Microbiology: Fundamentals and Frontiers. Washington DC: ASM Press. Pp. 728- 739. WHO. 1999. HACCP Principles and Practice. Teacher's Handbook. CD-ROM. Geneva: WHO. Woteki CE. 2000. Is There a Place for Food Safety Objectives in USDA's Food Safety Program? Online. FSIS, USDA. Keynote Address to the CERES Forum On Food Safety Objectives, Washington, DC, December 4. Available at http://www.fsis.usda.gov/OA/speeches/2000/ cw_ceres.htm. Accessed May 20, 2002. Wright AC, Hill RT, Johnson JA, Roghman M-C, Colwell RR, Morris JO Jr. 1996. Distribution of Vibrio vulnificus in the Chesapeake Bay. Appl Environ Microbiol 62:717-724. Yeung PSM, Hayes MC, DePaola A, Kaysner CA, Kornstein L, Boor KJ. 2002. Comparative pheno- typic, molecular, and virulence characterization of Vibrio parahaemolyticus 03:K6 isolates. Appl Environ Microbiol 68:2901-2909.