Why the Zero Tolerance Policy is unattainable

  1. Known and Unknown Pathogens –  

(show number of pathogens found in 10 years to assess what we likely don’t know and prove that we’ll never have the ability to identify them all or enforce zero tolerance on them)

The rate of discovery of new microbes, and the new associations of microbes with health and disease, has accelerated over the past two decades. Many factors are implicated. New pathogens have truly emerged wit the globalization of travel and trade, changes in demographics and land use, susceptibility to opportunistic organisms associated with immunosuppression, and climate change. Environmental, ecological, and demographic factors, with the ongoing evolution of viral and microbial variants and selection for drug resistance suggests that infections will continue to emerge and probably increase and emphasizes the urgent need for effective surveillance and control. (1)

Types of pathogens are viral, bacterial, fungal, other parasites and prionic (e.g. mycobacterium tuberculosi (a causative agent for most tuberculosis) and Fungus (affect Athlete’s Foot). A pathogen is a harmful organism that causes disease in its host and any foreign organism, which is not part of the body, and presents inside the body, mainly in the blood stream, but antigen is a part of the body. (2)

  • Weaknesses in Testing Methodology  –

(tests can’t tell between live/dead cells, can’t identify everything)

  • Adherence to Testing Protocol –

(Regulators don’t follow protocol)

  • Global Experts Weigh-In –

International experts opinions on zero tolerance policy including recommendations for alternatives)

  • A particular concern for the group was the use of criteria implying a zero tolerance for Salmonella and suggesting complete absence of the pathogen. The notion can be interpreted differently by various stakeholders and was considered inappropriate because there is neither an effective means of eliminating Salmonella from raw poultry nor any practical method for verifying its absence.

An example is the different criteria (and subsequent actions in the case of noncompliance) addressing the presence of Salmonella on raw chicken, all of which depend on the stage in the food chain, the sensitivity of the sampling plan and method, and the analytical method used.

Increasingly, risk-based concepts are being adopted for both domestic policy and international trade, despite sometimes being poorly understood and not always applied consistently or with transparency.

A recent risk assessment of Salmonella contamination in Belgian chicken meat preparations revealed that levels greater than 1 CFU/g were most likely to be associated with human salmonellosis (185).

Legislation has been introduced that makes testing compulsory and specifies deadlines for establishing the required targets in chicken breeders, layers, and broilers and in turkeys (56, 57)

Serovar-specific control measures. In some parts of the world, strategies have been adopted to target specific Salmonella serovars associated with both poultry and human salmonellosis. Salmonella Enteritidis caused a pandemic of human illness from infected layer and broiler flocks beginning in the 1980s (3). Particular strains of Salmonella TABLE 1. Prevalence of Salmonella-positive broiler flocks in the EU, 2005 and 2006 (61) Member state No. of flocks sampleda % flocks positive for Salmonella Austria 365 7.7 Belgium 373 15.3 Cyprus 248 10.9 Czech Republic 334 22.5 Denmark 295 3.1 Estonia 131 2.2 Finland 360 0.3 France 381 8.9 Germany 377 17.2 Greece 245 27.3 Hungary 359 65.7 Ireland 351 27.9 Italy 313 30.4 Latvia 121 9.1 Lithuania 156 5.1 Poland 357 57.7 Portugal 367 42.8 Slovakia 230 8.3 Slovenia 326 3.1 Spain 388 42.3 Sweden 291 0.0 The Netherlands 362 10.2 United Kingdom 382 10.7 a The number of samples taken was statistically determined. Pooled fecal samples were obtained from boot swabs, and five swabs per flock were tested. J. Food Prot., Vol. 73, No. 8 SALMONELLA ON RAW POULTRY 1569 Enteritidis with an apparent predilection for the reproductive tract of the laying hen were responsible for contamination of egg contents, resulting in vertical transmission

For Salmonella Enteritidis and Salmonella Typhimurium in particular there is a clear linkage between human illness and poultry consumption. Conversely, although all Salmonella serovars are considered to be potentially pathogenic to humans, some of those found in poultry are rarely if ever associated with human illness. A classical example is Salmonella serovar II 1,4,12,[27]:b:[e,n,x], also known as Salmonella Sofia, which is often isolated from chicken in Australia but rarely from human salmonellosis cases there (146).

Predominant poultry serovars differ among countries and can change over time within a single country or region (76), and successful control of one serovar may allow another to predominate. For example, epidemiological evidence suggests that Salmonella Enteritidis may have filled the ecological niche occupied previously by the antigenically related Salmonella Gallinarum, which was eradicated in most of the major poultry producing countries by the 1970s (148).

Feed can be a latent source of Salmonella for food animals because it is made from a wide range of potentially contaminated ingredients (44, 151). When present in dry feed, Salmonella can survive for more than 1 year, and even low numbers may be significant because for some strains ,1 cell per g is sufficient to colonize young chicks (157).

The heat sensitivity of nonsporulating bacteria, including Salmonella, is influenced by the temperature and time and the prevailing water activity of the feed. The heating process aims to eliminate Salmonella during pelleting, expansion, or extrusion and minimize any adverse effect on the nutritional quality of the feed (42, 50, 104, 119, 126). However, there is a significant risk of recontamination during post-pelleting stages of the milling operation and during storage and transport of feed. Because of this risk, various chemical treatments have been considered, e.g., addition of certain short-chain fatty acids, such as formic and propionic acids. These acids have many of the attributes that are desirable in a feed treatment (92, 113, 151, 189, 195).

Instead of depending on extensive product testing, a better alternative is to apply good manufacturing practices (GMPs) and hazard analysis critical control point (HACCP) principles to the manufacturing process.

Effective implementation of the HACCP system requires measures to prevent recontamination of the feed after heat treatment. As with raw ingredients, these measures involve adequate storage conditions (including rigorous dust control), appropriate control of transport vehicles, regular cleaning and disinfection of the vehicles, and protection of the load up to and including the point of delivery.

when used with water-immersion chilling systems, reduces the organic load in the chill water (168), making any added chlorine more effective. However, the removal of bacteria from carcasses in the spray washing process is not enhanced by using chlorine and/or hot water (137), probably because organisms that become firmly attached to the tissues are protected from the effects of these agents and are not easily removed (118, 138).

Chilling of poultry carcasses to about 4uC or lower ensures that any Salmonella present will be unable to multiply…or exposure to cold air either by passing carcasses through an air blast system or holding them in a chill room. The continuous immersion system has a washing effect that reduces microbial contamination by up to 1 log unit (131).

The U.S. system (170) also includes a zero-tolerance policy for visible fecal contamination on carcasses entering the chilling process (181) and the need for a HACCP plan to ensure that avoidance of fecal contamination is a critical control point (182). Otherwise, the determination of critical control points is a matter for the individual company, and their number and location are likely to differ among establishments (180).

No feasible sampling plan can guarantee the absence of Salmonella, but sampling on a regular basis will reveal changes in infection or contamination so that corrective action can be taken, as required. The sampling strategy should be defined according to the public health risk involved, the anticipated prevalence of the target organism, the desired level of confidence in the results obtained, and the general principles of statistical control, which will indicate the degree of confidence offered by negative results. Other factors to consider are the stage in the food chain at which samples should be taken, the type of sample in each case, how many samples to take at any one time, how often material is collected, and what quantity of the material to collect. Standardized methods of analysis should always be used; methods advocated for international adoption are provided by organizations such as the International Organization for Standardization (ISO) and the World Organization for Animal Health (OIE). There also is the question of who should carry out the sampling, although regulations may specify that sampling must be done, at least in part, by a competent authority (71). An effective control strategy requires detailed consideration of the nature of the food chain and the points at which sampling will provide the most meaningful information. No single sampling site is ever sufficient. Testing for Salmonella at any stage should always have a clear objective that is related to control of the organism, allowing appropriate action to be taken on the basis of the results obtained. Other factors include the likelihood of infection or contamination at a particular stage and whether there are practices or interventions that might minimize the risk. Resources can then be allocated appropriately and cost effectively in relation to the risk involved. However, feasible levels of sampling are not usually sufficient to determine fully the effectiveness of a specific control measure.

In monitoring the mill environment, Jones and Richardson (104) noted that TABLE 2. Sampling for Salmonella at different stages of the supply chain Stage in supply chain What to sample When to sample Feed manufacture Bulk ingredients Before use Mill environment and equipment Finished feed Grandparent or parent flocks Litter Sampling should be more intensive for grandparent stock; sample before and just after moving to production house Dead birds Dust Feces Surfaces and equipment After cleaning and disinfection Hatchery Internal surface of hatching cabinet After hatching Chick box liners Eggshells Meconium Dead-in-shell chicks Culled chicks Surfaces and equipment After cleaning and disinfection Broiler flocks Litter Before slaughter Dust Feces Surfaces and equipment After cleaning and disinfection Slaughter and processing Neck skin or carcass rinse After carcass chilling Plant environment and equipment After cleaning and disinfection Portioning and deboning Meat surface and skin As required Plant environment and equipment After cleaning and disinfection Wholesale (fresh and frozen) Meat surface and skin As required Retail Meat surface and skin As required J. Food Prot., Vol. 73, No. 8 SALMONELLA ON RAW POULTRY 1575 dust was consistently contaminated with Salmonella throughout the mill and especially near pellet coolers, which draw in large amounts of air. Thus, sampling of dust and the mill environment is much more effective than monitoring the end product, and the sampling should be done as part of a HACCP program (63, 197).

Sampling at retail. Testing products at the retail stage rather than during processing is more relevant to the exposure of consumers to Salmonella via raw poultry meat. The results obtained can be of greater value in assessing the human health risk, which is required in risk assessments, and in verifying the effectiveness of Salmonella control measures for different types of product. This information will provide a scientific basis for any new criteria that are deemed necessary. The sampling strategy should be based on statistical methods and related to the sources of Salmonella exposure for the majority of the population, i.e., it should be largely focused on retail products that are on display in major towns and cities and in the principal retail outlets from which most poultry meat is sold. All the main forms in which poultry products are marketed should be sampled, e.g., whole carcasses, portions, meat preparations, and fresh and frozen products, and it will be important to distinguish between domestic and imported products

The adoption of quantitative risk assessment practices in microbiological food safety underscores the reality that zero risk is unattainable for all raw foods, a reality in everyday events and everyday life. The choice of zero tolerance, implying the complete absence of a hazard, may be regarded as the expression of a regulatory preference for the precautionary principle and has little to do with food safety and human health (80, 176). In the United States, the Committee on the Review of the Use of Scientific Criteria and Performance Standards for Safe Foods formed under the National Research Council (135) noted that the term ‘‘zero tolerance’’ is commonly used but generally poorly defined or understood. Use of this language in expressing objectives is troublesome because the terminology has different meanings for different audiences, as highlighted by the definition the Committee offered for its own purposes: ‘‘lay audience perception of the absence of a hazard that cannot be scientifically assured, but is operationally defined as the absence of a hazard in a specified amount of food as determined by a specific method.’’ To some people, zero tolerance implies a notional concept of zero risk associated with the food or zero prevalence of a pathogen in the food commodity. Such a misunderstanding could easily arise from the pending EU requirement for the absence of Salmonella in 25 g of fresh (raw) poultry meat (56) because no details are given on how this requirement would be interpreted. In the absence of any means of eliminating the pathogen from a raw food product, the ‘‘zero’’ concept is misleading to those consumers who may interpret such regulations as implying no risk; these consumers would have unrealistic expectations of the effectiveness of regulatory action. If a hazard exists, there is some probability it will cause an adverse effect, no matter how small (85). Zero tolerance may also imply that both minor and major deviations from a policy will be treated with the same severity. This is obviously not a sensible approach to identifying and resolving problems. Internationally, there is no consistency in interpreting the concept and what action should result from any deviations. The purpose of a zero tolerance policy should be to provide an alert, leading to a review of control policies and procedures while permitting distribution of the final product to the marketplace in situations where withdrawal would not give a risk reduction proportional to cost and other practical considerations. Little is to be gained when dealing with food safety management practices based on microbiological criteria for end product testing alone (accept or reject) because even when a process is completely under control some, albeit small, probability exists for exceeding the established parameters (191, 203). Without knowledge of the degree of variability in a process or product or of where the uncertainties of a food process lie, the likelihood of exceeding the limits is unknown. Several other challenges exist to applying a zero tolerance policy for Salmonella in poultry meat: defining the accuracy, sampling intensity, sampling material, and method sensitivity. At which point is the assessment to be made, preharvest or postharvest, who bears the repercussions for enforcement, and who has and what is the enforcement capacity? Ultimately, regulatory choices in establishing control policies must be verified through scientific evidence for their effectiveness for reducing risk so that social costs can be made transparent (80).

The term ‘‘zero tolerance’’ for specific pathogens such as Salmonella in food products is interpreted differently by scientists and other stakeholders in different countries and therefore has been confusing, misleading, and misapplied. All countries signing the international WTO agreements are entitled to establish sovereign levels of protection. However, with regard to sanitary measures that include MCs, the most appropriate and legally defensible approach is to define such criteria by limits of detection according to the analytical method imposed and confidence limits of sampling and testing. Using terms such as ‘‘zero tolerance’’ or ‘‘absence of a microbe’’ in relation to raw poultry should be avoided unless these terms are defined and explained by international agreement. New metrics, such as POs that are linked to human health outcomes based on risk assessment, should be used throughout the food chain and will define the resultant public health risk.

In addition to principal authors listed above, members of the Salmonella on Raw Poultry Writing Committee include Raphael Andreatti Filho, Sao Paulo State University, Sao Paulo, Brazil; Roy Biggs, Tegel Foods Ltd., Auckland, New Zealand; Jeff Buhr, U.S. Department of Agriculture, Agricultural Research Service, Athens, GA, USA; Sarah Cahill, Food and Agriculture Organization of the United Nations, Rome, Italy; John Cason, U.S. Department of Agriculture, Agricultural Research Service, Athens, GA, USA; Thongchai Chalermchaikit, Chulalongkorn Univeristy, Bangkok, Thailand; Hector Hidalgo, University of Chile, Santiago, Chile; Charles Hofacre, University of Georgia, Athens, GA, USA; Henk Hupkes, Meyn Food Processing Technology, B.V., Oostzaan, The Netherlands; Mogens Madsen, Dianova, Aarhus, Denmark; Roel Mulder, Spelderholt Poultry Consulting and Research, Burg, The Netherlands; Lars Plym Forshell, National Food Administration, Uppsala, Sweden; Martha Pulido Landinez, Universidad National de Colombia, Bogota´, Colombia; Jason Richardson, The Coca-Cola Co., Atlanta, GA, USA; Douglas Smith, North Carolina State University, Raleigh, NC, USA; Yvonne Vizzier Thaxton, Mississippi State University, Mississippi State, MS, USA; Hajime Toyofuku, National Institute of Public Health, Japan; Pirkko Tuominen, Finnish Food Safety Authority, Helsinki, Finland; Mieke Uyttendaele, Ghent University, Ghent, Belgium; Sian Ming Shi, Shanghai Jiaotong University, Shanghai, China; and Marcel Zwietering, Wageningen University, Wageningen, The Netherlands.

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