According to the World Health Organization, 1 in 10 people in the world (about 600 million) falls victim to illness from contaminated food each year. Of that, about 420,000 die. Unsafe food not only causes disease—it also strains healthcare facilities and can hurt economics, trade, and tourism.

It’s estimated that food contamination costs the industry about $55 billion a year in the U.S. alone. For individual businesses, it can range from a few thousand to millions of dollars. Those numbers do not necessarily reflect other costs, including reputation to a facility and industry, and the ability to regain trust from suppliers and consumers.

Complicated international food supply chains help distribute more food around the globe, but also call for more vigilant food safety precautions at every step of the supply chain. The outbreak of E. coli O157:H7 in several states from romaine lettuce is an example of how the complexity of the produce supply can create significant challenges to maintaining food safety.

Quickly identifying potential contamination sources is a key part of protecting the food supply chain. Since its introduction, adenosine triphosphate (ATP) bioluminescence-based monitoring of surfaces and even some products has been invaluable to identifying possible sources of contamination. Within seconds, food processor professionals can now monitor safety levels, identify contaminant areas, and more effectively set up and fine-tune Hazard Analysis and Critical Control Points (HACCPs).

While ATP monitoring is considered easy to use and interpret, there are a number of cautions of how the instruments and monitoring systems should not be used. The following are five warnings about how not to work with ATP monitoring.

Don’t Confuse ATP with Direct Bacteria or Viral Detection

ATP is the energy-containing molecule that is found in every living cell. Therefore, it is a useful indicator that contamination may exist on a surface or other part of the food supply chain, from irrigation water to farm to processor, transporter, handler, or retail market. But since all cells contain ATP, a positive reading in relative light units (RLU) will indicate any cell, and not just bacterial cells. Furthermore, not all bacterial cells cause disease. And viruses, which are not technically living cells, usually do not contain any ATP at all.

Nevertheless, ATP monitoring is valuable because it points to areas where bacteria (and, to a more limited degree, viruses) may lurk. After all, bacteria are cells, and areas that record very low RLUs have fewer cells and are far less likely to harbor pathogenic microorganisms. Other tests, such as enzyme-based or bioluminogenic devices based on specialized substrates, can determine the presence of specific bacteria, including E. coliEnterobacterColiform, or total bacteria counts, within hours. Still more sophisticated tests, like those using the polymerase chain reaction, can identify specific bacteria or viruses, sometimes within a day. Traditional methods like cell culture may take days to generate results, but commonly can verify species of bacteria.

Don’t Use on Soiled or Pre-Cleaned Surfaces

Many users of ATP monitoring can fall into the trap of measuring environmental surfaces before cleaning, hoping that those readings can be compared to readings taken after cleaning and/or sanitization steps. While those readings should be significantly different (hopefully!), ATP luminometers and mostly importantly the testing devices were never meant to be used on uncleaned surfaces. This is because it is easy to overload the swab part of the testing device with microorganisms, which can significantly impact results.

As the universal energy molecule, ATP is found in all animal, plant, bacterial, yeast, and mold cells. Product residues, particularly food residues, contain large amounts of ATP. Microbial contamination contains ATP, but in smaller amounts. After cleaning, all sources of ATP should be significantly reduced.

The test is designed to detect invisible or trace amounts of product residue. When performing sample collections, it is important to make sure not to overload the swab bud with too much sample. Some products in very high concentration can inhibit the bioluminescence reaction.
This also means that when collecting a sample, you should make sure to use aseptic techniques. Do not touch the swab or the inside of the sampling device with your fingers.

Don’t Assume a High Reading Indicates Supply Chain Failure

ATP monitoring is a valuable tool for determining the potential for contamination and can help improve processes at every step in the food supply chain. Too often, a reading with high RLUs, indicating potential contaminants and possibly even pathogens, is interpreted as a failure of personnel to keep things clean. To counteract this misperception, ATP monitoring can be used as a staff or contractor training tool.

Any successful cleaning efforts require a plan, including setting up an HACCP process. ATP can provide nearly instantaneous data to find possible gaps in your processes that can be quickly and efficiently closed by changing cleaning methods, protocols, or locations. Far better to identify potential issues at an early stage than later when pathogens can cause costly shutdowns. Furthermore, a high RLU indicates that intervention and cleaning steps need to be taken, and re-testing the same area can determine the effective of those efforts.

Training should include the use of ATP monitoring and the efficient use of data storage and tracking, which relies on software packages (such as Hygiena’s SureTrend cloud-based software) that can record trends in your facility and point out areas that need improvement. This is also helpful when supply sources, technology, and equipment are changed, which will alter how you monitor and clean your facility. Training efforts and a quest for continuous improvement should be an integral part of your facility’s culture, and the data that comes from ATP monitoring can form a solid foundation for creating that culture.

Don’t Under Sample

A cleanliness monitoring system should be thorough enough to sample every potential area where contamination could possibly occur. Food contact areas (direct and indirect) and hard-to-clean areas should be the main focus of your swabbing program. Direct contact areas are surfaces where the presence of any contaminant will taint the final product. Indirect contact areas are those where splashed product, dust, or liquid has the potential to be dropped, drained, or transferred onto the product. Hard-to-clean areas may include filler heads, O-rings, nozzles, and areas with irregularly-shaped surfaces, corners, grooves, and cracks.

A recent study showed that some amount of over-sampling (overlapping some areas at times) can be an effective way to get robust ATP results and prevent possible contamination. While Hygiena advises structured, repeated cleaning schedules on key environmental surfaces and a sampling area of 4 x 4 inches, certain intricate surfaces in food contact areas may benefit from using smaller sampling areas, such as 2 x 2 inches. Re-testing is still a vital part of maintaining facility cleanliness, too.

Don’t Test Inconsistently

Hygiena advocates for the development of a comprehensive cleaning schedule and map of environmental surfaces, including the sampling of “high touch” areas in facilities. The schedule should include multiple sampling sites on a surface and reliable recordkeeping on online reporting tools to track cleanliness and re-testing of areas, especially those areas that result in higher RLUs. A number of researchers claim that ATP measurements suffer from too much variability in results partly because of inadequate cleaning and monitoring strategies.

Consistent testing starts with a solid plan and means to evaluate it:

  • Set up all the locations, users, and test plans before testing so that running reports is easy and accurate;
  • There’s no need to create reports from scratch—preprogrammed reports can be modified and saved;
  • Graphs can be quickly converted to line, bar, or pie charts depending on preference;
  • Sharing reports with team members in regular meetings initiates a conversation on improvement opportunities and positively reinforces successes;
  • Share these reports with executives and quality committee members to demonstrate how ATP cleaning verification helped improve cleanliness; and
  • Compare these reports to any existing contamination/bacterial infection data to correlate cleaning improvements with infection rate reductions.

Consistency isn’t just about sampling locations, however. For consistent readings, surfaces should be swabbed in the same conditions (always wet or always dry). This will make it easier to compare data and look for trends that might need attention.

A successful contamination prevention effort will involve some amount of planning, training, and evaluation for effectiveness. As the world’s food supply chain gets more complex and global in scope, an adaptable yet robust monitoring plan will be essential to maintaining a safe food supply. Reducing foodborne illness by just 1 percent would keep approximately 500,000 people from getting sick each year in the U.S. Reducing foodborne illness by 10 percent would prevent 5 million people from getting sick annually.

ATP-based testing is now a worldwide standard method as a first step toward rapidly identifying potential reservoirs of pathogens, so problems can be corrected—and prevented—before they become serious, or even deadly.