Environmental monitoring programs (EMPs) are widespread throughout the food, dietary supplement, and animal food industries, as these industries manufacture ready-to-eat (RTE) products. Under the U.S. Food and Drug Administration (FDA's) Preventive Controls for Human Food regulation, an EMP is a verification activity for a sanitation preventive control. A strong sanitation program will clean and sanitize food-contact and non-food-contact surfaces to remove and kill pathogens. A robust EMP seeks to find the pathogen, followed by intensified sanitation and a root cause investigation.

EMPs are not just documents to be written and forgotten, but living systems that require active management on a weekly basis. As managers with multiple roles and responsibilities, it is crucial to ensure that your EMP is not just in place, but also effective. This article discusses three key challenges for evaluating an EMP.

Challenge No. 1: An EMP is Unique to a Facility

Managing an EMP is a team effort that should be led by the facility. An EMP is a complex program that requires the collective expertise and involvement of a facility team. While corporate may be involved in the initial drafting of an EMP, the facility EMP team should take ownership of its implementation and management.

An EMP is written based on the facility's blueprint and its flow of foot traffic, wheeled traffic, and ingredients through processing steps. The facility water and air, plumbing, sewage, and trash flow are considered. Designate Zone 3 and Zone 4 areas on the blueprint. Zone 3 areas contain Zones 1 and 2 surfaces, with Zone 1 being food-contact surfaces and Zone 2 being non-food-contact surfaces proximate to Zone 1. If the facility has a kill step and separation of the raw side from the post-kill step side, then areas on the raw side are Zone 4. That makes the majority of the area on the blueprint of most facilities Zone 4. The highest-risk area for environmental pathogen cross-contamination is post-kill step processing, up to the sealing of the primary package. If the facility does not have a kill step (e.g., a blending operation), then Zone 3 areas start with the exposure of opened ingredients to the environment. Zone 3 surfaces tend to be part of the room from ceiling to drains. Zone 2 surfaces are the most difficult to identify and tend to be the parts of equipment below the level of product.

Part of the challenge in writing an EMP is creating the master site list. Once consensus is reached on the zone designations across the facility, the EMP team compiles a list of each site to be swabbed. A small facility may have a total of 100 sites; a large facility may have over 500 sites. Both extremes are rare, and most facilities list closer to 200 sites. There is no "magic number." Create a list that works for you. The master site list typically notates the area or room, the specific site's description, and the site's zone. In addition, many facilities assign a sample site number to simplify the labeling of swab bags and the submission of samples to third-party testing laboratories. Create the master site list on a spreadsheet to sort by zone. When the team reviews the list of sites by zone, there should be a long list from Zone 1 and a short list from Zone 4. The lists from Zones 2 and 3 will be somewhere in the middle for the number of sites.

The next decisions are very challenging. For each of the four lists of sites by zone, what is the frequency of completing the rotation of sampling every site in the zone? The answer is, "it depends." The frequency will depend on the risk of the product to an environmental pathogen, the control of the pathogen at the facility, the previous positive results in the product, and the facility's food safety culture, among other considerations. A general rule of thumb is to complete the rotation of sites from Zone 1 within one month and the rotation of sites from Zone 4 quarterly. The rotation of sites from Zones 2 and 3 will be completed within one, two, or three months. If there are ten drains in a Zone 3 area and the rotation is completed quarterly, do you really want to wait another three months to swab a drain when drains are notoriously contaminated? Completing the rotation of sites in Zone 3 within four to eight weeks may be more appropriate for the control of an environmental pathogen. All of this is based on risk, and the general rule may not work at your facility.

The next step is calculating the number of sites to swab from each zone weekly. If there are 100 sites in Zone 1 on the master site list and the rotation is one month, then 25 sites must be swabbed weekly. Include sites from Zone 1 weekly to catch potential problems early. If there are ten sites in Zone 4 and the rotation is quarterly, one or no site can be swabbed weekly, two sites biweekly, or some combination. It is important to note that many facilities have a random number generator to choose the site for sampling. It is more important to ensure that the master site list for each zone is completed within the rotation than to randomize the sampling sites. When a random number generator is solely followed, some sites may be skipped for a long time.

What will happen over time? You will see positive or negative trends as you plot the data and review the results holistically by the quarter, semi-annually, and/or annually. You will identify problem areas like a drain that tests positive occasionally. There may be consistently negative sites that can be dropped from the master site list. More sites tend to be added over time, so it is good to drop some sites, with justification and as appropriate.

Challenge No. 2: Is Corrective Action Initiated on a Presumptive or Confirmed Positive Result?

One of your best resources is the people at your third-party testing laboratory. Someone can clearly explain the advantages and disadvantages of different indicator or pathogen methods, not just based on cost, but also time to results, sensitivity of the method, and validation of the method for environmental samples instead of product samples. Specific methods exist for environmental samples of sponges, swabs, water, and air. All methods are not created equal.

A big warning here is to never take (or submit) a sample unless the corrective action is known. If a non-food contact surface tests positive for a pathogen, what will the first step be for corrective action? For most facilities, the answer is intensified cleaning. What does that mean? Write a Standard Operating Procedure (SOP) for the decision-making and define the next steps after a positive. With a well-written SOP, an EMP team is not making decisions with each positive, but everyone is following the SOP.

Not all positives are created equal. When a pathogen method is ordered for an environmental sample, most methods have the steps of presumptive positive, confirmed positive, identification, and serotype. Each step in the method adds more and more time when corrective action needs to be initiated. Most facilities order serotyping for investigational testing, but not routine testing. Identification is also common for investigational testing, but not as common for routine testing. Pre-define the corrective action based on results of routine testing. If the corrective action will be the same despite the result being a presumptive positive, confirmed positive, or identified pathogen, why wait the extra days? That is valuable time wasted that could have been used to perform intensified sanitation and a root cause investigation.

A facility may get notice of a presumptive positive, although the sample does not confirm it. A facility may get notice of a confirmed positive, and the sample does not identify as the pathogen but as a close relative instead. It can be frustrating. There should not be a sense of relief when the pathogen is not confirmed. There is an important point here. Most pathogens are not competitive. The site that tested as even a presumptive positive means the site is conducive for a pathogen. It also means that the pathogen may have been present in small amounts and missed in the testing. The pathogen may have been outcompeted in the environment, the testing, or both. In microbiology, we say negatives mean nothing and positives mean everything, because it is very difficult to find a pathogen (i.e., get a positive pathogen result).

So, back to the challenge question: Is corrective action initiated based on a presumptive or confirmed positive pathogen result? Take presumptive pathogen results seriously. If the corrective action is the same for either a presumptive pathogen result or a confirmed pathogen result, you do not need to wait for confirmation or identification to initiate corrective action. Testing costs may be reduced when testing stops at presumptive positives.

Challenge No. 3: Does the Root Cause Investigation Locate the Source of the Pathogen?

A big red flag is when managers say they do not have time to investigate the source of the pathogen. That happens a lot in industry: a pathogen is found, sanitation is intensified, further swabbing is negative for the pathogen, and everyone moves on. Then, the pathogen comes back later. What was, and is, the source? Ingredients, humans all the way back to the agricultural workers in the field, and transportation vehicles from the field to processors to manufacturers are all potential sources of contamination, in addition to the environment, air, and water at a facility.

Why is a successful root cause investigation important? If the source of the pathogen is not found, then the pathogen will reappear and eat up resources again and again. FDA does not think kindly of facilities with recurring pathogen results and the potential of a resident pathogen, because the facility may be manufacturing contaminated product over a long period of time and endangering public health.

Addressing these three challenges of EMPs is resource-intensive, but the payoff is huge for customer loyalty and the protection of public health. Food safety is a management program for continuous improvement, and an EMP should not be written and shelved, but continue to evolve.

Kathy Knutson, Ph.D., PCQI, is the Founder of Kathy Knutson Food Safety Consulting LLC. She is also an author and the former Chair of the Education Committee for the National Cannabis Industry Association (NCIA), with expertise in the fields of bacteriology, food science, and education. She speaks, writes, and trains on U.S. Food and Drug Administration Food Safety Modernization Act (FDA FSMA) compliance, and has trained over 500 Preventive Controls Qualified Individuals (PCQIs) throughout her career. Dr. Knutson works with managers to help them write thorough hazard analyses, food safety plans, recall plans, environmental monitoring programs, and allergen programs. Additionally, she travels to manufacturers to conduct swabbing to locate pathogens during recall investigations, as well as for gap assessments of Good Manufacturing Practices (GMPs) for cannabis-infused edibles. In 2020, Dr. Knutson published her book, titled, Food Safety Lessons for Cannabis-Infused Edibles.