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An Epidemiological Model for HACCP Verification

Opinion

(Roy Costa is a registered sanitarian and president of the consulting firm Environ Health Associates Inc. More of his articles can be found here.)

Knowledge and Capability of Auditors

HACCP systems have grown and changed remarkably over the past 50 years, yet the fundamental scientific reasoning for critical controls has not changed in any substantial way. The goal of HACCP is to provide a system of critical control points so that risks to consumers can be reduced to safe levels, prevented, or eliminated.

http://www.dreamstime.com/royalty-free-stock-images-production-sausages-sausage-factory-image29444599The sixth principle of HACCP — Verification — was developed to assure the effectiveness of these critical controls and to validate the scientific basis for them.

Verification is primarily the responsibility of operators through an internal audit process, although independent auditors (third-party auditors) play an increasingly important role in this complex task.

The following persons may be involved in verification:

  1. Public health agents
  2. Consultants
  3. Second-party auditors
  4. Third-party auditors

Verification should accomplish two things:

  1. Assure the scientific basis for hazard controls (validity).
  2. Evaluate the capacity of the management system to control hazards.

Before performing an effective verification of a HACCP management system and critical control points, auditors must have very keen knowledge of the science upon which the critical controls are based.

The areas of scientific background needed by auditors include microbiology, chemistry and the physical sciences. In addition, because the HACCP system is a type of total quality management system (TQM), auditors should also be familiar with management concepts.

Public health protection is the responsibility of our government, yet recently there has been an emphasis on public health protection in the field of auditing, along with an attendant legal liability. In addition to verification and validation of food safety systems, we can now add the legal responsibilities of operators and auditors alike to protect public health and safety to the verification process.

Infectious Disease Transmission Through the Environment

The science of epidemiology studies the various factors associated with the propagation and spread of diseases and other unwanted human health conditions. By itself, epidemiology cannot prove causation, but along with the knowledge of associated risk factors, biological plausibility, and a clear pathway for transmission, we can make a solid hypothesis for causation. Understanding what causes foodborne illness is at the very basis of performing a proper verification of a HACCP system.

A third-party auditor must have a complete understanding of environmental factors involved with the safety of a process, together with the scientific association of those factors with disease transmission. With these in hand, auditors can make sound judgments on the severity of risk and the efficacy of controls.

In order for disease transmission to occur, there must first be an agent. Second, that agent must have an environmental pathway to a susceptible host. Third, the agent must reach a portal of entry and cause an exposure.

Epidemiological Triangle

(Microsoft Word - HACCP Systems for Food Safety and Third Party

The Triangle has three corners called vertices:

  • Agent, or microbe, that causes the disease (the “what” of the Triangle).
  • Host, or organism, harboring the disease (the “who” of the Triangle).
  • Environment, or those external factors that cause or allow disease transmission (the “where” of the Triangle).
  • The arrows point in both directions, illustrating the routes of transmission.

Auditors can use this relationship to understand significant risks in a process and where critical controls are needed, but only if they have sufficient information about the risks for transmission in the environment and the agent, its infectivity, and its ability to survive in the environment, along with other factors affecting virulence.

There are three basic types of infectious microbial agents: bacteria, virus, and parasites (unicellular and multi-cellular), many with unique attributes. In addition, there are also pathogenic fungi, physical, chemical and radiological hazards. There are a great number of varieties of infectious and toxigenic foodborne agents, with at least 200 human foodborne diseases identified.

There are three factors associated with foodborne disease transmission:

Contamination: The presence of unwanted substances in foods (chemical, physical, biological, radiological). Adulteration ensues when unsafe levels of them are reached in a final product.

Growth: The proliferation of bacteria. There are three intrinsic factors that affect bacterial growth: nutrient content (including growth inhibitors), moisture, and pH, and there are three external factors: temperature, time and atmosphere (aerobic vs. anaerobic).

Survival: The ability of microorganisms to adjust to changes in the environment and to remain infective in an environmental niche.

An auditor must be able to assess the potential for these three associated factors to occur in any process in order to make a judgment as to the likelihood of occurrence of a hazard and the controls required.

Verification Tools

Currently, auditors (other than government agents) do not routinely sample food or environments when determining the effectiveness of a HACCP system. Visual observations and a detailed review of record-keeping are the usual methods used.

When public health agents are conducting verification, they use sampling of the environment, along with product samples, to assess the effectiveness of both the GMP program and the process controls. Such tools give validity to the verification findings and provide some measure of effectiveness.

The same tools used by operators to monitor controls are available to auditors, yet they are not routinely used. These include:

  1. Test kits for antimicrobial strength of solutions
  2. Thermometers, thermocouples and data loggers
  3. ATP bioluminometers
  4. Oxidation-Reduction Potentiometers and pH meters

Findings of Epidemiological Investigations as Sources of Critical Control Points

The findings of outbreak investigations and environmental surveys conducted by public health agents provide much useful data for prevention. For example, at the retail level, CDC has identified five leading risk factors for foodborne illness transmission. While their relative importance may change somewhat from reporting period to reporting period, the factors themselves are consistent:

  1. Food from unsafe sources
  2. Improper temperature control
  3. Cross-contamination
  4. Poor employee health and hygiene
  5. Inadequate cooking

One of the key challenge for auditors is to stay abreast of the latest findings in the investigation of foodborne illness. Unlike the data provided in CDC studies of foodborne illness outbreaks at the retail level, auditors do not have a single list of factors to be aware of in other sectors of the food supply.

The investigation of the Listeria monocytogenes outbreak in cantaloupe revealed new information for auditors in the area of fresh produce safety. It was learned that the cantaloupe packing line used only city water, with no antimicrobial added to wash (cool) the melons. FDA cited this as one of the critical failures in the operation. Reduction of harmful bacteria to safe levels may not be possible on the rough surface of a cantaloupe using an antimicrobial wash. However, the failure to keep the process water from being a means of cross-contamination has added a new dimension to the understanding of critical controls with this particular commodity.

Other Sources of Information About Critical Controls

Epidemiological findings provide a scientific basis for determination of critical control points, but there are other sources of information about critical controls that can be used:

  1. Buyer requirements and industry standards
  2. Regulations
  3. Scientific research

Buyers of food, along with the industry itself, have come to their own understanding of critical controls. Washing of produce, for example, is often cited by the produce industry as a requirement to include in a HACCP plan as a critical control. However, there is inconsistency in this approach and too often such requirements do not have a sound scientific basis.

Government regulations tend to be more scientific; however, political considerations often enter in the decision-making process and affect what controls agencies deem critical.

The scientific literature provides peer-reviewed and authenticated information about foodborne illness hazards and the effectiveness of controls. The practical application of the scientific research into food safety is fundamental to a valid HACCP system, but much of the research has yet to have a practical application, and the findings may appear contradictory.

The best information about critical controls and what is essential to include may come from a firm’s own validation study to quantifiably characterize system performance. Validation studies are intensive scientific investigations that require experts in many fields of science, such as process control, microbiology, and chemistry.

Strengthening the Verification Process

Food safety auditors need a firm foundation in the causes for foodborne illness in order to carry out an effective and meaningful verification of a HACCP plan. The findings of foodborne illness investigations, along with knowledge of the many foodborne agents and their ability to contaminate, grow and survive in food production processes, provide such a basis.

Auditors must stay informed about the scientific research regarding food safety in their respective industry.

The proper tools to obtain empirical data need to be made available to auditors, along with the ability to collect and analyze the results of environmental sampling.

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