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Environmental monitoring program considerations

15 July 2022

Find out how to implement an effective environmental monitoring program. 

As part of the US Food Safety Modernization Act (FSMA), food companies supplying the US market need an effective environmental monitoring program (EMP) to minimise food safety risks by testing the environment for microbial contamination and allergen cross-contact. 

The first step to consider when developing an EMP is what team will evaluate the facility’s operation to help identify potential areas of risk and concern. These will be specific to the facility and can include factors such as the food produced and the expertise of the personnel. 

The team must then identify the regulatory requirements they must adhere to and what the EMP can easily address. The next step is to identify a list of potential pathogens and allergens to control and monitor. The team must then map out the facility areas and surfaces to be sampled. It is vital to select a variety of surfaces to sample to ensure the manufacturing environment remains as clean as possible (and to confirm that mitigation interventions are working). Typically, a facility is mapped out into four Zones – Zone 1 being the highest risk areas to Zone 4 being the lowest risk areas.

It is critical that, for each zone, a science-based environmental testing and verification program is established to effectively monitor all zones for overall hygiene quality. This involves establishing what type of testing will be performed for each swabbed site and when. Closely tied to this is the development of steps to take in the event of a positive test. It is crucial to understand what equipment or surface tested positive and why. 

Lastly, the team must select a qualified laboratory that uses accepted testing methodology so there is confidence that testing results are reliable and protect both the consumer and the facility’s product and brand.

When testing for contaminants, both food and non-food surfaces are swabbed to identify the presence of pathogenic bacteria, indicator organisms, or allergens. In addition, raw materials and finished products can also be tested for these contaminants. Indicator organism testing is often used to evaluate the risk of pathogen presence and provides more rapid time to results.

Once finalised, the documented EMP should list the target pathogens, indicator microorganisms, spoilage organisms and allergens, the location of sampling sites, the frequency of sampling and testing, when the samples should be taken, the sampling and analytical methods, and the name of the certified laboratory that will perform the testing. 

Corrective action procedures should also be included to address any positive test results and all records should be fully documented and stored for subsequent access and analysis. Samples may be taken on a daily, weekly or monthly basis – depending on the risks and the facility’s budget – and should focus on the primary pathogen control area. 

Zone establishment
As mentioned, there are typically four defined zones:

Zone 1: Includes all surfaces that come in direct contact with the food product – Work tables, utensils, pumps, belts, conveyers, hoppers, packing stations, employee hands, storage silos, racks and bulk containers.

Typically, Zone 1 is tested for Aerobic Plate Count, indicator organisms (such as EB), or Adenosine Triphosphate (ATP). It is not generally tested for pathogens, except in extreme circumstances. If Zone 1 tests positive for a pathogen, production must halt immediately, and the most likely outcome is that products produced in that zone will be recalled. 

Typically, Zone 1 testing for pathogens occurs when investigating a root cause, opening of a new production line, or when a ‘positive’ is found in adjacent zones or in product.

Zone 2: Includes non-food areas of contact that are directly adjacent to Zone 1 and could have high impact on the safety of the food product – it includes framework of Zone 1 equipment, drip shields, railings, areas above and below the production line, maintenance tools, ancillary equipment such as compressors and heat exchangers, chill units and aprons/tables. Zones 2 – 4 are typically tested for pathogens.

Zone 3: Includes non-food areas of contact that are not close to or adjacent to Zone 1 but still could be in the production room — Walls, floors, ceilings, drains, sinks, footbaths, handling units, hoses, phones and finished product storage areas.

Zone 4: Includes areas located remotely from food production and processing – Maintenance rooms, lockers/break rooms, refrigerators, doors, office areas, warehouse areas, sanitation washrooms and loading docks. Zones 2 to 4 should already be routinely monitored by many facilities to prevent product contamination and often include specific tests for Listeria and Salmonella.

Sampling sites
When it comes to frequency of sampling, there are no set rules and standards. Often, testing in Zones 2 to 4 is done weekly, while ATP monitoring testing is done in Zone 1 before a line is released for production. However, different facilities must establish best-practices based on specific needs.

Areas can be sampled in several ways – contact plates, swabs and wipes, direct surface agar plating or rinsing and vacuum collection. No matter what process is used, however, there are basic protocols to follow. 

First, work outward from Zone 1 to Zone 4. Be sure hands are clean and gloves are worn for sampling. Make certain to submit a negative control swab for comparison and transport samples at temperatures under 45 °C and ensure testing occurs within 48 hours of collection or refrigerate samples. It is also of utmost importance to establish the proper cadence for testing and the number of samples to collect per zone. Two of the most common weaknesses in EMPs is the lack of sufficient samples, either per sampling event or from not sampling often enough. Not taking sufficient samples frequently enough defeats the purpose of an EMP. The second weakness is not having an action plan for positive results and following it.

Initially, sampling must be done at high levels (25-50 swabs/zone/day for a month). Following this, sampling can be reduced to weekly or even monthly in Zone 4. Over time, this data will be used to establish and refine baselines and review action levels. It is best to collect and review six to 12 months of data to identify trends and determine the ideal baseline and action levels. 

Indicator organisms
Indicator organisms are typically present in food or the environment and are not pathogenic. Therefore, they can be used to assess the cleaning and sanitation
processes in place within a facility. Zone 1 is usually routinely tested for indicator organisms while other zones may be tested for both indicators and pathogens. 

Indicator organisms are chosen and added to an EMP for the following reasons:

• Indicator organisms are less expensive and save time compared to pathogens.
• Low level presence of pathogens limits the practicality of performing pathogen testing.
• Indicator organisms are often present in high numbers, so they are easily enumerated.
• Indicator organisms have similar growth properties and requirements as pathogens, so they are easy to propagate under normal environmental conditions.
• Indicator organisms are non-pathogenic, so they pose no risk to containment facilities/labs that analyse samples.

While not a substitute for pathogen testing, indicator organisms can help trend the maintenance of proper cleaning within facility zones and quickly identify potential issues. 

Level of detection
In addition to testing for the presence of indicator organisms, it is often necessary to understand the level of contamination. This may be important in situations where pathogens are present in low levels, as regulations often allow these levels of some organisms in food. Some facilities, for example, may process carcasses where a positive on one carcass is much different than contamination across multiple carcasses. The former allows isolation of the issue to a restricted zone while the latter risks discarding an entire processing line of meat. There are also requirements for quantifying levels on Listeria in ready-to-eat (RTE) food products, and quantitation can also aid in root cause determination and understanding how well cleaning efforts are working.

Two options commonly used for quantitative testing are most probable number (MPN) and direct plating. MPN is a traditional enrichment-based analysis where a series of dilutions are performed from a single sample homogenate.
Tests are often done in triplicate to ensure accurate results. While very sensitive, this testing method is also resource-intensive but it can detect low levels of common pathogens. Direct plating involves homogenising a sample in diluent and then removing a small volume for plating. This method has a higher limit of detection so is not suitable for detection of low levels of pathogens. Rapid detection methods, such as PCR have many advantages including increased sensitivity and speed of detection, and identification of microorganisms from numerous and varied sample matrices. Compared to MPN and direct plating, the detection time required for the assay can be reduced from days or weeks to hours. In addition, these methods are particularly applicable to target organisms expected to be present in low numbers.

Summary
Implementing an effective EMP ensures that each facility has an ‘early warning system’ for the detection of potential issues in the food manufacturing and processing systems. In addition, it can measure the performance of the overall food safety program, using data-based information to demonstrate the cleanliness of the facility. It also ensures sanitary design, personnel practices, and operational methods are in control and validated.

This article uses information from a Hygiena whitepaper entitled ‘Establishing an EMP in your facility: What to consider’. This can be downloaded from www.hygiena.com 


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