Zone 1 Listeria Testing – Yes or No?

Jan 4, 2019

We’ve all been exposed to the threat of foodborne illness, whether from the scares at Chipotle, the recent E. Coli outbreaks in Californian romaine lettuce, or the millions of pounds of produce recalled every year across industries.

Of the recalls caused by pathogens, listeria monocytogenes holds a commanding lead as the most common adulterant. In 2017, over 500,000 pounds of food were recalled due to Listeria outbreak, causing an estimated 1,600 infections in humans. Approximately 20% of those infections were fatal, making listeria the third-leading cause of death from foodborne illness.

In 2017, over 500,000 pounds of food were recalled due to Listeria outbreak, causing an estimated 1,600 infections in humans.

As the stats indicate, listeria is an unfortunately common threat. To prevent it, food production companies typically use environmental swabs to test different zones in their facilities, ranging from Zone 1 (places in direct contact with food) to Zone 4 (non-contact surfaces outside of the processing areas). Zones 2 and 3 refer to surfaces that don’t touch the food directly but are in somewhat close proximity to it.

If the tests are positive, corrective action is taken by the producers to destroy any contaminated product, sanitize the area, and if necessary, initiate a recall of products that made it to the shelves.

The case against testing Zone 1

Within the food safety realm, however, there is a debate over whether Zone 1 testing is necessary or even advisable. Some argue it’s unlikely that surfaces in direct contact with the end product will have listeria given that they are routinely cleaned. Plus, these opponents say, end-products have to be held—sometimes for days—while the testing takes place. In an industry where freshness is key, it becomes difficult for producers to justify letting fresh food wither and potentially go to waste while waiting on a cleanliness confirmation.

The case for testing Zone 1

On the other hand, Zone 1 testing proponents argue that comprehensive environmental testing should be mandatory and that those who don’t test Zone 1 may be remaining intentionally ignorant in order to avoid expensive yield reductions or recalls. “If you have faith in your sanitation step,” says Dr. Andrew Flannery, Vice President of Development at PathSensors, “then you should have no problem with testing Zone 1 because you’ll be confident that it’s clean.” Of course, the same logic could apply to the argument against Zone 1 swabbing. If producers have confidence in their sanitation step, then why bother testing?

Although it’s possible to skip Zone 1 testing and ship out perfectly healthy food, the fallout from missing the presence of a pathogen like listeria can be detrimental. On average, food recalls cost companies about $10 million in lost revenue, which does not include the cost of any associated reputational damage. Recalls may also contribute to one or more of the hundreds of deaths caused annually by listeria.

Additionally, with the passing of more stringent food safety legislation in recent years—such as the Food Safety Modernization Act (FSMA)—many facilities are choosing to implement Zone 1 testing rather than accept the risk of a potential recall.

On average, food recalls cost companies about $10 million in lost revenue, which does not include the cost of any associated reputational damage.

The choice of whether or not to test is a difficult one and may not have an objectively correct answer.

What do you think? If you’re involved with food production, we’d love to hear your opinion. Do you test Zone 1 for listeria or other indicator organisms? Leave a comment below, or contact us here to learn more about listeria testing.

About PathSensors

PathSensors is a privately held biotechnology company deploying proprietary CANARY technology, exclusively licensed from MIT-Lincoln Laboratory. PathSensors technology has been designed to detect extremely low levels of biological threats in minutes. Additional information is available at https://www.pathsensors.com.

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Cooper Temple
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ctemple@pathsensors.com
443.887.4003

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