Many companies have built their food quality, safety and sanitation programs to include some kind of microbiological and/or environmental monitoring. 

These programs may include the following:

  1. Monitoring for environmental pathogens
  2. Hygiene monitoring (Is the plant clean or being cleaned properly?)
  3. Air sampling
  4. Random testing of workers or other suspect items

But the big question to many in the industry is: “Do we need to establish a program for environmental monitoring for pathogens?”

I have worked with processors who have told me that they lost points on third party audits because they did not have an environmental monitoring program for pathogens. If these operations were manufacturing ready-to-eat items, I must agree with the auditor, but this was not true in all cases. Some auditors wanted companies that were manufacturing products such as carbonated soft drinks and high-sugar syrups to have such a program. To help answer this question, look to the Preventive Controls for Human Food regulation (21 CFR Part 117.130 ( c) (ii).

The hazard evaluation required by paragraph (c)(1)(i) of this section must include an evaluation of environmental pathogens whenever a ready-to-eat food is exposed to the environment prior to packaging and the packaged food does not receive a treatment or otherwise include a control measure (such as a formulation lethal to the pathogen) that would significantly minimize the pathogen.

So a product like a carbonated soft drink or the high-sugar syrups mentioned above (which are usually cold filled) may not require such a program because the formulation itself is shown to be lethal to environmental pathogens. In fact, a company alluded to above that was dinged on its audit had conducted challenge studies on its products that clearly showed these items were not only lethal to environmental and other pathogens, but also to several potential spoilage organisms. If you as a processor are manufacturing products, especially an RTE item that may be lethal to pathogens, it may be worth your while to look into conducting a challenge study. Long term it would probably save money. If the study demonstrates that a formulation is not only bacteriostatic (inhibitory), but also bactericidal (lethal), pathogen monitoring could be eliminated.

This is not to say that processors should not do any kind of swabbing. One of the challenges with doing hygiene monitoring is setting limits. What total count do you set?  Ten, 100, 1,000 organisms per swab? Many people simply don’t know what total counts mean or the significance of the numbers. The same people may also believe that ATP swabs are an indicator of microbial load on a surface, which is simply not true. A hygiene monitoring program using ATP swabs, protein swabs for allergens or swabbing for total counts should be considered as a verification tool for ensuring that cleaning and sanitizing is properly done. Cleanliness is next to godliness as some say.

So let’s just assume that an environmental monitoring program for pathogens is not only a legal requirement, but also something that your food safety team feels is an essential element for protecting your products, your brand, your customers and your good name. If your food safety team thinks that way, all I can say is kudos to you. 

Environmental monitoring programs for pathogens are designed to seek out Listeria monocytogenes and Salmonella sp. Listeria is the target organism in plants manufacturing high-moisture, RTE products such as luncheon meats, smoked fish, pastas, salads and a many other foods. Salmonella is of concern with low-moisture foods such as nuts, nut butters and organic dried fruits. According to Thomas Jones at the Dried Fruit Association of California, years of testing sulfured fruits indicate that these products are pathogen free.

The Almond Board of California understands the importance environmental monitoring for salmonella. The ABC mandated that California almonds be processed to eliminate salmonella following outbreaks in 2001 and 2004 attributed to raw almonds. As part of its efforts to control salmonella and protect the industry as a whole, the group has published a document called “Pathogen Environmental Monitoring Program,” a guide on how to develop and implement an environmental monitoring program for salmonella. (The document may be accessed at

The industry has developed a zoning system for environmental sampling that applies to both pathogens. The zones are as follows;

  • Zone 1: Product contact surfaces (PCS)—fillers, hoppers, belts, screens, brushes, etc.
  • Zone 2: Non-product contact surfaces adjacent to or within close proximity of PCS—frameworks, support systems, refrigeration units
  • Zone 3: Non-product contact surfaces distant from PSC area—air return covers, phones, hand trucks, forklifts, drains
  • Zone 4: Areas outside processing area—locker rooms, cafeteria, hallways, loading dock, maintenance areas

John Butts, president of the consulting firm Food Safety By Design, is an acknowledged expert on listeria control and a proponent of an environmental pathogen control program he has dubbed “Seek and Destroy.” This program has been developed through years of experience working in the industry. The cornerstones of this program are twofold—aggressive sampling and following the data. Aggressive sampling is an area that is lacking in many environmental programs. Processors are doing the sampling, yet they are not really trying to find the pathogen. They sample easy-to-clean areas or minimize sampling during production, a time when pathogens may have been transferred from a harborage site onto equipment or the food itself. 

So how does a company set up an environmental monitoring program? There are several elements that make up such a program. The following elements need to be developed, documented, implemented and maintained, and how these programs are developed is product and process dependent. What an operator does when producing low-moisture foods and targeting salmonella will differ from a processor manufacturing RTE meats. You should establish:

  1. Sampling sites
  2. Sampling frequency (a schedule)
  3. Test methods and who will do the testing
  4. Corrective actions including product holds

Dr. Butts’ “Seek and Destroy” program goes beyond basic monitoring. It incorporates aggressive sampling as noted, but also utilizes a team approach to evaluate existing equipment and potential new purchases; cleaning and sanitizing procedures and validation; and potential risks from all zones, including zone 4. The program also incorporates the 10 basic principles of sanitary design developed by the American Meat Institute. (See sidebar.)

AMI principles of sanitary design

  1. Cleanable to a microbiological level
  2. Made of compatible materials
  3. Accessible for inspection, maintenance, cleaning and sanitation
  4. No product or liquid collection
  5. Hollow areas hermetically sealed
  6. No niches
  7. Sanitary operational performance
  8. Hygienic design of maintenance enclosures
  9. Hygienic compatibility with other plant systems
  10. Validate cleaning and sanitizing protocols

Establishing sampling sites: The team must establish sampling sites for each line and all four zones based on risk. Among the factors that should be incorporated into the assessment are difficulty of cleaning, need for equipment assembly/disassembly, design and makeup of the equipment, and potential for accumulation of foods. As an example of equipment design and makeup, a smooth belt would be easier to clean than one made of links or mesh. When establishing sampling sites, the number of swabs or product samples collected per sampling period must be determined. As an example, if a processor intends to swab 10 sites at a time in a zone, it should choose 20-30 sampling points. The sites should be numbered, photographed and selection set up so they vary week to week. Easy-to-clean sites should not be used. Varying sampling sites ensures that the cleanup crew, which watches what goes on, doesn’t emphasize one area that’s tested regularly. Some operations utilize a random number generator to select which sites will be targeted. 

Frequency of sampling: Establish how often you’ll conduct sampling and how many sites will be tested. Frequency, or scheduling, has two elements: how often samples will be collected and at what time or times during processing operations. When starting up an environmental monitoring program for pathogens, it would be good to follow the advice of Dr. Butts: Sample aggressively. So you might collect samples every week. As part of the aggressive startup, a processor might also make a decision to collect extra samples. One element that must be included in a pathogen monitoring program is to collect samples during the production runs, say from three to six hours after startup. This helps determine whether pathogens may be in the products being manufactured or are being relocated from harborage sites during the process.

Test methods, or who does the work: Very few processors with established environmental monitoring programs for pathogens actually do the testing in-house. It is expensive and, since there are pathogens involved, requires the proper facilities and well-trained personnel. Most companies utilize a third-party laboratory.  

The laboratories often help the operator set up the sampling plan, provide sampling tools and training, and establish collection programs to ensure that samples are gathered and processed promptly.

The processor needs to determine what kind of testing will be done. Depending upon the type of product, the target pathogen may be salmonella or listeria. Processors must decide whether they want to test for indicator organisms, such as coliforms, enterobacteriaceae or total counts. One point that should be emphasized is that most processors do not do pathogen testing on samples collected from zone 1, the food contact surfaces. Pathogens are targeted in zones 2, 3 and 4, however.

It is a good idea that whenever environmental testing is done, especially when testing for pathogens, the processor should place all product manufactured on that day on hold until the work has been completed and the samples are found to be negative. Many companies do this as part of their positive release program; that is, no product is released until all test results are in. Many processors have decided that the discovery a presumptive positive is grounds for a product hold. They even ask the testing laboratory to stop the test at that point. This leads up to our final point: corrective actions. How this will be managed is a function of product, process, history and an ongoing review of test data. A well-established program with lots of data that has demonstrated both product and process control may not require holding product when swabbing for Listeria monocytogenes.

Establish corrective actions: All processors need to establish corrective actions for the discovery of positives in all zones. This includes presumptive and confirmed positives for pathogens and elevated counts for indicator organisms. Corrective actions need to be developed, documented and implemented. This is where Dr. Butts’ “Search and Destroy” program comes to the fore. The goal is to ensure that product safety and quality is protected, and that the data is utilized to determine the why, how and where of the results that prompted the corrective actions.  Guidance for corrective actions for salmonella may be found in the Almond Board of California’s guidance noted earlier.

Get it done

Processors manufacturing RTE products that are exposed to the environment must establish an environmental monitoring program.  It is now mandated by law for those industries, but not mandated across the board. Hopefully, these guidelines will help processors develop and implement their own programs.  


Thomas Jones, senior director of analytical services, DFA of California/Safe Food Alliance, 

John Butts, Food Safety By Design, 

Almond Board of California,