5 Things Not to Do With ATP Monitoring

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. coli, Enterobacter, Coliform, 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.