Dead cockroaches
Bug Bytes

The Gray Zone of Insecticide Repellency: Revisiting Long-Held Assumptions About Pyrethroid Effects on Pests

By Alvaro Romero, Ph.D.
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Dead cockroaches

Insecticide efficacy is often equated with direct mortality — but that’s only part of the story. Some compounds, especially neurotoxic insecticides like pyrethroids, produce sublethal effects that disrupt pest behavior and physiology without causing immediate death. These responses may include irritancy, hyperactivity, avoidance, mating disruption, or interference with aggregation and feeding behavior. Sublethal exposure could impact a pest’s ability to mate and pass on its genes. While the pest may be alive, the product has “removed” the pest from their ultimate biological goal of reproduction.

In mosquito control, sublethal exposure to pyrethroids can trigger behavioral changes — either through detection of insecticides at a distance (repellency) or agitation after contact (irritancy) —both of which can reduce human-vector contact. While these categories often overlap, it is useful to distinguish between them: repellency involves sensory-driven avoidance without contact, typically mediated by olfactory receptors in the antennae, whereas irritancy results from neurotoxic effects that provoke escape responses after contact.

Among these sublethal responses, spatial repellency plays a particularly important role in mosquito management. Volatile insecticides delivered via spatial sprays or emanators create an airborne barrier that discourages mosquitoes from entering or remaining in treated areas. For pests such as termites, ants, cockroaches, bed bugs, and other occasional invaders, sublethal responses to insecticides are often viewed as problematic. It is commonly—but incorrectly—assumed that these pests can reliably detect and avoid treated surfaces. In reality, predictable and consistent repellency is primarily observed in subterranean termites. Although ants are often believed to avoid insecticide-treated areas, studies show that they typically continue foraging over such surfaces, suggesting that true repellency does not apply. For most other pests, behavioral responses to insecticides vary depending on species, physiology, environmental context, and product formulation. Below, we explore how these sublethal effects influence outcomes for key urban pests when exposed to pyrethroids.

Not So Repelled: Why German Cockroaches Still Cross the Line

German cockroaches offer a compelling example of how sublethal insecticide effects can challenge traditional assumptions about repellency. Pyrethroids are widely considered to provoke strong and predictable behavioral responses, including repellency. However, recent studies under controlled laboratory conditions have demonstrated that German cockroaches still make contact with pyrethroid-treated surfaces—contradicting the common belief that these compounds are strongly repellent. This finding is consistent with the low volatility of many pyrethroids, which limits their potential to exert true spatial repellency. These observations have led to the suggestion that placing cockroach gel baits on or near pyrethroid-treated surfaces may not diminish bait effectiveness, as cockroaches appear to continue foraging over treated areas. While contact with pyrethroids can produce an irritant effect that prompts temporary retreat or relocation to untreated zones, cockroaches often resume nocturnal activity and may re-encounter treated surfaces or nearby baits, resulting in continued exposure. More research is needed, particularly on formulations that combine neonicotinoids with pyrethroids, to better understand how these chemistries interact to influence contact irritancy, avoidance behavior, and foraging dynamics in cockroaches under both laboratory and field conditions.

Termites: A Distinct Case of Ground-Level Repellency

Termites are one of the few pest groups that consistently demonstrate true repellency to some insecticides—especially pyrethroids like permethrin, bifenthrin, and cypermethrin. Numerous studies have shown that subterranean termites actively avoid soil treated with these compounds, altering their tunneling behavior or abandoning the area entirely. This reliable avoidance response plays a key role in forming chemical barriers that protect structures by preventing termite entry. Because of this consistent behavior, pyrethroid-based termiticides have long been marketed and used as repellent soil treatments, in contrast to non-repellent options like fipronil or imidacloprid, which termites unknowingly traverse, enabling colony-level suppression through horizontal transfer.

Ants: A Case Where “Repellency” Doesn’t Apply

The commonly held belief that pyrethroids always act as repellents has been challenged in ants, with research showing that foraging individuals do not actively avoid pyrethroid-treated surfaces. Although ants are highly sensitive to chemical cues and communicate extensively through pheromones, studies have demonstrated that ants continue to behave normally—following trails and foraging—even after stepping onto treated areas. The perceived “repellency” in some cases likely results not from active avoidance, but from the insecticide killing foragers before trails are firmly established. Field trials, such as those involving Argentine ants and bifenthrin-treated panels, further support this: ants continued to cross treated surfaces and died within minutes, without evidence of behavioral avoidance. These findings suggest that pyrethroids can be used effectively against ants in perimeter applications, provided formulations are applied strategically to zones of activity.

A similar response might be expected in other occasional invaders—such as scorpions (Fig. 1), stink bugs, lady beetles, boxelder bugs, ground beetles, earwigs, crickets, and sowbugs—which often move along treated structural edges and surfaces both around buildings and when entering indoor spaces. While further research is needed to better characterize the behavioral responses of these pests to pyrethroid-based formulations, leveraging the contact-based exposure observed in ants could improve the overall effectiveness of insecticide applications in both indoor and outdoor general pest management programs.

Conclusion: Rethinking Repellency in Pest Control

The idea that pyrethroids universally repel pests is an oversimplification. As this review shows, true and predictable repellency is largely limited to subterranean termites, whose soil-foraging behavior makes them uniquely sensitive to pyrethroid-treated zones. For other pests—including ants, cockroaches, bed bugs, and occasional invaders—behavioral responses to pyrethroids are far more nuanced. Many species do not actively avoid treated surfaces, and in some cases, sublethal effects such as agitation or increased mobility may even enhance exposure to insecticides or drive pests toward strategically placed control tools like baits or dusts.

Recognizing the complexity of these sublethal responses is essential for developing effective, pest-specific strategies. Rather than treating repellency as an all-or-nothing phenomenon, pest management professionals should consider how formulation type, application strategy, and environmental context influence pest behavior. When approached thoughtfully, sublethal effects—often seen as limitations—can instead be leveraged as assets, helping to improve outcomes across a range of urban pest control programs. This may be especially true for occasional invaders, where non-repellency can promote greater contact with treated surfaces and increase the likelihood of effective control.

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References

  • Haynes, K. F. (1988). Sublethal effects of neurotoxic insecticides on insect behavior. Annual Review of Entomology, 33, 149–168. https://doi.org/10.1146/annurev.en.33.010188.001053
  • Moore, D. J., & Miller, D. M. (2006). Laboratory evaluation of insecticide product efficacy for control of Cimex lectularius. Journal of Economic Entomology, 2080–2086.
  • Romero, A., Potter, M. F., & Haynes, K. F. (2009). Behavioral responses of the bed bug to insecticide residues. Journal of Medical Entomology, 46, 51–57.
  • Thanispong, K., Achee, N. L., Bangs, M. J., Grieco, J. P., Suwonkerd, W., Prabaripai, A., & Chareonviriyaphap, T. (2009). Irritancy and repellency behavioral responses of three strains of Aedes aegypti exposed to DDT and α-cypermethrin. Journal of Medical Entomology, 46, 1407–1414
  • FMC Australasia. (2021). Repellents vs Non-Repellents: It’s Not All Black and White. FMC Corporation educational brochure. © FMC Australasia
  • Romero, A., Agnew, J., Paysen, E., & Blakely, B. (2021, October 19). Arizona bark scorpions and their responses to insecticides. PCT Convention Extra 2021. https://www.pctonline.com/article/arizona-bark-scorpions-and-their-responses-to-insecticides/
  • Gaire, S., Gondhalekar, A. D., & Scharf, M. E. (2024). Behavioral responses of field‐collected German cockroaches to pyrethroids and implications for resistance management. Pest Management Science, 80, 4323-441.

 

Veterinary Drugs Analysis, Food Safety
Bug Bytes

Texas A&M Researchers Study Diet’s Impact On Salmonella Prevalence In Cattle

By Megan Bennett
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Veterinary Drugs Analysis, Food Safety

Salmonella is one of the leading causes of foodborne illnesses in the United States, according to the Centers for Disease Control and Prevention, and can spread to people from a variety of foods, including beef. Understanding how and why cattle become infected with Salmonella is an important part of fighting this major public health concern.

Researchers at the Texas A&M College of Veterinary Medicine and Biomedical Sciences (VMBS) are addressing this problem from a new angle by studying how diet and feeding schedule impact Salmonella infections in cattle.

Their recent study, published in the American Society for Microbiology’s Microbiology Spectrum journal, found that high-starch diets can potentially lower Salmonella prevalence in cattle, especially within the lymph nodes — organs that are often embedded in fat trims included in ground beef products.

“Lymph nodes may be present in fat trimmings that are used to balance lean-to-fat ratios in ground beef products,” said Yesica Botero, a fourth-year biomedical sciences Ph.D. student. “This is a food safety concern because Salmonella can hide inside lymph nodes, where surface cleaning or treatments do not reach. As a result, it can still be present in ground beef.”

Feedyard cattle are typically fed a high-energy, grain-based diet designed to promote rapid growth and efficient weight gain.

Understanding the role that a high-starch diet potentially plays in reducing Salmonella prevalence could have major impacts on the beef cattle industry, providing ranchers with new options for controlling the spread of bacteria within their herds.

Taking A New Approach

The Texas A&M project was designed to study feedlot cattle that Dr. Kendall Samuelson, from West Texas A&M University, was examining in a separate project to see whether high-starch diets and feeding schedules impact liver abscess formation.

“We aimed to understand the factors that contribute to the presence and distribution of salmonella in feedlot cattle,” said Dr. Gizem Levent, a VMBS assistant professor in the Department of Veterinary Integrative Biosciences. “There aren’t many studies focusing on understanding how diet and management changes impact Salmonella.”

Botero and Levent took samples of feces, hides, lymph nodes and soil from Samuelson’s cattle pens over a period of more than seven months. They found that while there was little difference in Salmonella populations between cattle with scheduled versus erratic feedings, the level of starch in the diet made a notable impact.

“We saw a reduction in Salmonella, especially in the lymph nodes, when cattle were fed a high-starch diet,” Botero said. “High-starch diets typically cause a lower pH in the rumen, which may be what reduces Salmonella prevalence in the gastrointestinal tract and, subsequently, in lymph nodes.

“Findings from Dr. Samuelson’s original study suggested that high-starch diets may also correlate with a higher incidence of liver abscesses,” she said. “This is something we would like to explore further in upcoming studies by testing different starch concentrations in the diet to find one that does not harm cattle health — such as by increasing the risk of liver abscesses — but still helps lower Salmonella levels.”

Continuing The Investigation

In addition to studying how different levels of starch impact liver abscesses and Salmonella, Levent and Botero are planning to dive even deeper into the data to study the specific serotypes, or genetic profiles of Salmonella, observed in their samples.

“We want to do a follow-up study with more in-depth analysis of the dynamics of the Salmonella population,” Botero said. “By looking at the genetic profiles, we can better understand which serotypes are present, how they might respond to antibiotics, and whether they carry genes that make them more likely to survive or spread in the environment.”

Fortunately, what they have seen so far from the feedlot samples does not indicate a high presence of Salmonella or serotypes resistant to antibiotics.

“The overall Salmonella population found was not resistant to antibiotics of public health concern, which is good news for public health,” Levent said. “But we will definitely keep screening for resistance so that we can better understand what makes resistant populations exist in the environment.”

Romaine Lettuce
Ask The Expert

Heavy Metals in Rice and Leafy Greens: Paths to Reductions

By Neal Saab, PhD
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Romaine Lettuce

Some food contaminants arise from natural or agricultural environments where crops are grown. Examples include heavy metals which are sometimes present in leafy greens like spinach and grains like rice. If concentrations of these and other heavy metals exceed certain thresholds they can pose risks to public health, especially in younger populations. Both food groups are critical components of nutritious and wholesome diets. But the risks posed by sometimes significant levels of heavy metals are giving health experts pause and prompting new research into how to reduce potential risks in vegetables and grains without reducing or eliminating these healthy foods from diets.

The sensitivity of children to heavy metals/toxic elements has led the U.S. Food and Drug Administration to establish a ‘Closer to Zero’ initiative to reduce them in the food supply. This often involves addressing important food groups like vegetables and rice.

Leafy greens like spinach, kale and lettuce can absorb metals like cadmium and lead which are often naturally found in the soil. But they do so in different ways and in different parts of the plant. And the potential for arsenic to accumulate in rice under certain growing conditions is leading researchers to explore steps both farmers and home cooks can take to reduce the metals’ presence.

One study led by Dr. Angelia Seyfferth at the University of Delaware and supported by the food safety and nutrition research nonprofit IAFNS uses spinach to compare and contrast how cadmium and lead differ in how they move through soil and accumulate in plant foods. The paper also discusses practical pre- and post-harvest techniques to reduce human exposure to these metals that can be adopted by farmers, food processors and consumers.

The study, “Mitigating Toxic Metal Exposure Through Leafy Greens: A Comprehensive Review Contrasting Cadmium and Lead in Spinach,”1 appears in the peer-reviewed journal GeoHealth. This review highlights differences in the magnitude of exposure, bioavailability, and the practicality of mitigation strategies and calls for more research on cutting chloride inputs to leafy green crops like spinach, kale and lettuce to reduce plant uptake of cadmium.

According to the authors, “It is paramount to understand the soil and plant factors that dictate contaminant accumulation in edible tissues to identify mitigation strategies for metals in foods.”

They recommend action during both crop cultivation and product processing. “Pre-harvest techniques are generally actionable by the grower and include soil preparations and amendments, irrigation practices, and cultivar selection. Post-harvest techniques are further downstream and include spinach handling in the field, washing either by a factory or by the consumer, and other consumer-driven choices regarding diets.” The paper also looks at mitigation steps for lead and other metals in several crops.

Alternative Cultivation

Another study supported by IAFNS in the journal Science of Food finds that alternative cultivation practices that reduce water use may reduce greenhouse gas emissions and arsenic concentrations in rice crops but may inadvertently also boost levels of cadmium in rice plants. That paper, Unintended Food Safety Impacts of Agricultural Circular Economies2, with Case Studies in Arsenic and Mycotoxins, makes several findings.

For example, continually flooded rice paddy production — the traditional method of producing rice — boosts arsenic levels in rice. But alternate wetting-drying rice production reduces the risk of arsenic uptake from soil. However, dryer soils may lead to greater uptake of cadmium in crop plants. The authors remind readers that alternative cultivation practices are not all-or-nothing strategies. For example, rice farmers often carefully weigh the specific amount of flooding and dry field management in a manner that optimally reduces both arsenic and cadmium uptake by their crops.

A third IAFNS study, Agronomic Solutions to Decrease Arsenic Concentrations in Rice3, suggests that the most effective treatments for reducing levels of the toxic metal arsenic in rice are cultivar selection, irrigation management, cooking approach and the application of selenium or silicon soil amendments. This research appears in a recent article “Reducing the Risk of Arsenic in Rice” in Food Safety Tech. The article pointed out that both farmers and home cooks can take steps to reduce arsenic.

Postharvest Techniques

Partially cooking and drying the rice is known to reduce arsenic. Rinsing, soaking and disposing of the leftover water are viable methods of reducing arsenic for home cooks. For example, cooking methods that involve briefly parboiling rice (partially cooking in boiling water before finishing by steaming or other methods) and discarding the parboiled water lowered levels of arsenic up to 83%.

The presence of heavy metals in healthy foods like leafy greens and rice pose potential public health challenges and require creative research, analysis, and engagement with stakeholders throughout the supply chain. New research is identifying workable solutions to this issue that can be applied by all stakeholders from growers to consumers. IAFNS is proud to catalyze new science that is mitigating the risks of toxic metals in foods.

References

1 Seyfferth, A.L., Limmer, M.A., Runkle, B.R.K., Chaney, R.L. (2024). Mitigating toxic metal exposure through leafy greens: A comprehensive review contrasting cadmium and lead in spinach. GeoHealth, 8(6).  https://doi.org/10.1029/2024GH001081

2 Scott, C.K., Wu, F. (2024). Unintended food safety impacts of agricultural circular economies, with case studies in arsenic and mycotoxins. Science of Food, 8(52). https://doi.org/10.1038/s41538-024-00293-8

3 Leavitt, M.E., Reba, M.L., Seyfferth, A.L., Runkle, B.R.K. (2025). Agronomic solutions to decrease arsenic concentrations in rice. Environmental Geochemistry & Health, 47(209). https://doi.org/10.1007/s10653-025-02508-7

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Listeria
Ask The Expert

Where Listeria Comes From, and How it Moves Around

By Bob Lijana
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Listeria

Listeria is widely distributed in nature, found in soil, water, vegetation, and animal feces. And since it can be found in soil, it has the ability to contaminate vegetables and produce grown in that soil. This can also occur if contaminated manure is used as fertilizer.

Thus, it is quite easy for Listeria to get into a food plant on someone’s shoes, or equipment being brought in from outside, or ingredients coming from a supplier.

Given the ubiquity of Listeria, a good food safety team (and their management) always assumes that the organism is present somewhere in the plant. Even with regular microbiological sampling coming up negative (i.e., no Listeria found), that is not a reason to lower the level of vigilance. Ever.

The insidious nature of Listeria is such that it can hide, even in untoward conditions, and it can be moved around, up, down, and sideways. The same factors which allow Listeria to enter a plant allow it to be transported within that plant.

Let’s talk about “harborages” and “movement vectors.”

Harborages are all areas in a plant which have the necessary conditions for Listeria to grow. Biofilms (resistant coatings which protect the organism) can offer an additional level of security for the organism. Listeria may or may not grow, but it can certainly survive. These areas (e.g., underneath equipment, in drains) are also called “growth niches” in the scientific literature.

Movement vectors are those locations in which harborages intersect with people and equipment moving around the plant. These are the opportunities for Listeria to move. These points (e.g., a fork truck running through contaminated water) are also called “transfer points” in the scientific literature. An example:

  • An employee accidentally drops Listeria-laden potatoes on the floor.
  • The employee walks through those potatoes and across another production line to get a stainless steel scoop to clean up the potatoes.
  • The employee walks back through the clean production line to scoop up the dirty potatoes, throw them in a trash container, and then put the scoop back.
  • Another employee, not observing any of this, picks up that scoop later to sample ready to eat potato salad.

As you can infer, unbeknownst to the employees, the potatoes were harborages for Listeria, and the scoop (and footwear) were movement vectors likely resulting in Listeria getting into food.

Now think about all of the movement and travel of people and equipment that occurs in your own plant. You may even see the following:

  • Fork trucks moving pallets from a warehouse to a product zone.
  • Stainless steel carts wheeled from one line to another.
  • Production operators carrying ingredients from one line to another.
  • Maintenance tool boxes being set on the floor, and then carried to another location.
  • Mixing implements being used and then hung for ready use later without being cleaned.
  • Bowls containing work-in-progress being wheeled across production lines on their way to a cooler.
  • Employees leaving their production line to get to a break area by walking across other production lines that use different allergens than theirs.

Best practices for Listeria control necessitate that harborages are eliminated and movement vectors are identified and controlled. Attacking Listeria in this way can reduce food safety risk dramatically. Note that the root source is almost assuredly a harborage site (a hiding spot for Listeria). So one of the best ways to find that harborage site is by identifying and mapping movement in the plant. Then follow the movement backwards and forwards, and up and down. You may find yourself surprised at where water can run or come from. And therein lie the “eureka” moments.

The objective is to identify the true root source of the Listeria, and eliminate it. This is very different than simply finding some Listeria and tossing sanitizer on it—this is very common, and people are lulled into believing that the Listeria has now been controlled. This is hardly ever the case if the root source has not been eliminated and if the movement vectors have not been identified and actively managed.

See the Related Articles below to read the series.

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Listeria
Ask The Expert

Listeria-related Regulations, FDA & USDA

By Bob Lijana
No Comments
Listeria

To enforce food safety regulations, FDA and USDA have a “zero tolerance” policy for Listeria monocytogenes (Lm) in certain foods. This means Lm must not be found in any 25-gram sample. According to FDA’s Compliance Policy Guide, legal action may be recommended if Lm is found in a ready-to-eat (RTE) food that allows Lm to grow. While the compliance guide is not legally binding, the finding of Lm in your facility could still lead to enforcement by FDA.

Do note that this is a regulatory policy. It does not mean that the typical healthy individual cannot tolerate Lm. Quite the contrary, as recognized by other countries (such as New Zealand, Canada, and the European Union), some foodstuffs are allowed up to 100 CFU/gm of Lm (although the EU tolerance is supposed to change to “not detectable in 25 gm” as of June 1, 2026). For some foods, Japan allows even higher levels. Because of these higher limits, some people believe that allowing some level of Lm in a food is a very practical approach.

That said, the USA does not. Any food company—big or small—can face public health warnings, safety alerts, product withdrawals, or recalls because of Lm. No one is exempt if something goes wrong with how food is handled or processed.

Unfortunately, even with past mistakes and costly recalls, Lm-related recalls still occur. Some recent examples:

  • July 2025: recall of over 350,000 lb of turkey bacon (Kraft Heinz—Oscar Mayer).
  • June 2025: recall of chicken alfredo meals; at least 16 people hospitalized; at least 2 deaths (FreshRealm–Kroger and Walmart).
  • May 2025: recall of nearly 90 vending machine sandwiches and other products; at least 10 people hospitalized (Fresh & Ready Foods).
  • Apr 2025: recall of nearly 2,000 cases of ready to eat celery sticks (Duda Farms).
  • Feb 2025: recall of frozen supplement shakes; 12 deaths (Lyons Magnus–Sysco).
  • Jan 2025: recall of 2,000,000 cases of doughnuts and pastries (FGF Brands–Dunkin).
  • Oct 2024: recall of 12,000,000 lb of pre-cooked meat and poultry (Bruce Pack).
  • Oct 2024: recall of 200 varieties of frozen waffles and pancakes (Treehouse Foods—Food Lion, Harris Teeter, Publix).
  • Aug 2024: recall of 7,200,000 lb of sliced deli meats; 10 deaths (Boars Head).
  • Feb 2024: recall of 50 different cheese products; 2 deaths (Rizo Lopez Foods—Albertson’s, Trader Joe’s).

Even if one disagrees with the scientific basis for a “zero-tolerance” approach, all regulations require an ongoing vigilance to Lm presence in the plant environment (and of course in the food). This includes non-regulatory food safety schemes such as SQF (Safe Quality Foods). The current SQF Code (which is being updated for 2026) includes a requirement for a risk-based environmental monitoring program for pathogen detection, sampling, and eradication. To help in this regard, both FDA (“draft guidance for industry”) and USDA (“compliance guideline”) have excellent technical guidance documents. These publicly-available resources cover the microbiological aspects of Lm, how to identify Lm, and how to assess risks in order to determine appropriate preventive and corrective actions.

Regulators also use DNA testing in their quest to find root sources of Lm. Whole genome sequencing (WGS) is like testing for one’s ancestry. Listeria samples can be categorized based on their genetic (DNA) makeup. With an extensive database (e.g., PulseNet) FDA may be able to link the DNA from a Lm environmental sample in a plant with the DNA from a blood sample from someone who has been hospitalized with listeriosis. If FDA can also determine that the food was purchased in the same state as the plant is located and/or that the hospitalized person said that they ate that specific food, then FDA can link everything together.

Food manufacturers need to be aware of how WGS can affect their operations. A publication on this topic provides useful perspective from FDA’s point of view and the manufacturer’s point of view. These do not always align.

Regulations help protect the public health. Use these regulations as guides to protect the food you make.

See the Related Articles below to read the series.

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Listeria
Ask The Expert

Listeria 101, the first article in a series on Listeria in Food Plants

By Bob Lijana
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Listeria

“Listeria” is a family of bacteria. Almost all of the family members get along well with each other and with humans–so much so that people often do not even know the names of these “friendly” bacteria. But one member of the family, Listeria monocytogenes, is a bad actor, a pathogen. If a susceptible person (e.g., immunocompromised) gets infected with Listeria monocytogenes, they could easily get listeriosis. Consequences of this infection include sepsis, meningitis, encephalitis, and death.

Listeria was named in honor of a famous British surgeon, Sir Joseph Lister (from whom the trade name Listerine also comes from), who advocated for the use of antiseptics during surgery. Microbiologically speaking, Listeria species (i.e., “Listeria spp.”) are Gram-positive, facultative anaerobes, which means that they can grow in environments which do not have much oxygen.

Listeria monocytogenes (Lm) is one of the most virulent food-borne pathogens. It can be found in dirt, sewage, rivers and streams, rotting vegetation, and animal feces. Hence, it can easily find its way into a food facility through someone’s shoes, or equipment, or ingredients brought into the plant.

Lm is an extremely strong organism, able to survive pH ranges of 4 to 9, and temperatures from 32F to 113F. It can survive freezing conditions, very dry surroundings, and salty environments. The organism will not necessarily grow under those conditions, but once those conditions revert to more favorable ones, it can begin to grow again. Lm often forms “biofilms” (protective matrices) that protect the organism from being found and make it that much harder to eradicate.

All of these characteristics make Listeria an insidious pathogen.

FDA has published a summary of Lm in “Get the Facts About Listeria.” This summary includes statistics, background, and references. FDA also has a well-vetted set of microbiological procedures to identify Lm in its Bacteriological Analytical Manual.

A thorough microbiology reference book is “Modern Food Microbiology”. Chapter 3 discusses the characteristics of foods which affect pathogen growth, and Chapter 25 covers listeriosis.

Other Listeria species, such as Listeria innocua and Listeria welshimeri, are not pathogenic, and actually compete with Lm. So a microbiological sample taken which is positive for L. innocua might lead one to conclude that Lm is not present when it really is.

Food manufacturers and regulators often judge cooked foods as less risky than ready-to-eat (RTE) foods because cooking kills bacteria. Foods with low pH, preservatives, and/or low water activity (these are sometimes referred to as formulation hurdles) may also be judged as lower risk. However, don’t assume cooked or preserved foods are free of Listeria monocytogenes, as it’s a tough organism. Do your testing and validation work to confirm that Lm is under control.

Editors Note:  This article is the first in a series of six brief articles on Listeria. They are intended for food science professionals, especially food safety and quality assurance people. The information presented in these mini-articles will also be of interest to people in all functions.

See the Related Articles below to read the series.

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Track and Trace, traceability, supply chain

Traceability Is a Competitive Advantage, Not Just a Regulation

By Ellie Gabel
No Comments
Track and Trace, traceability, supply chain

Traceability adoption in the food and beverage industry is normalizing. It is expanding across jurisdictions, highlighting a desire for greater food safety. Legislators and technological innovations are in a perfect place to enable the most advanced solutions in history.

They will enhance operational productivity while promoting a trustworthy brand. Compliant companies are global health stewards, and customers demand food chain traceability to reduce risk. It is time to be an early adopter.

Regulatory Drivers in Food Chain Traceability

The Food Safety Modernization Act (FSMA) in the U.S. asserts that the global supply chain is responsible for maintaining public health. Traceability is a central tenet, emphasizing more robust recordkeeping and faster removal of potentially contaminated products.

The European Union also requires traceability as part of the General Food Law Regulation. If the source presents a safety concern, manufacturers are required to recall it and notify the authorities to determine whether it demands greater attention. Traceability highlights how food safety is a national affair.

Food quality control guidelines vary worldwide, and many prioritize safety. The Hazard Analysis Critical Control Points framework forces companies to identify potential biological, physical and chemical contamination sources. Analyses must cover the food’s origin, working environment and transportation medium. Other valuable guidelines include the Good Manufacturing Practices and nationally specific legislation. These have laid the foundation for new regulations.

Noncompliance will cost companies more than auditor fines. Quality oversights will begin without tracking traceability, driving customers to more adherent and reputable businesses. Additionally, organizations must deal with adverse health care implications if they neglect adherence.

Digital Tools Powering Modern Food Chain Traceability 

Data management, food manufacturing
Managing the data required for FSMA compliance is an ideal example of the importance of pursuing digital transformation in food manufacturing facilities. (Image courtesy of One Neck IT Solutions, LLC

Manual documentation is sufficient for tracking food. However, modern tech expedites the process and eliminates tedium, increasing the likelihood of continuous compliance. It allows companies of all sizes to commit more to enhancing traceability and maximizing the value of those efforts to achieve competitive advantages. These are some of the most notable:

  • Blockchain: Rapidly validates and uploads immutable digital certifications and logs transactions
  • The Internet of Things (IoT): Automatically senses and scans smart tags to enable real-time food monitoring
  • Cloud infrastructure: Seamlessly eliminates siloes and encourages collaboration through immediate information sharing
  • RFID tags: Quickly capture metadata about food sources
  • Enterprise resource planning systems: Immediately connects stakeholders throughout the food’s value chain in a single dashboard

Markets like the IoT will have an estimated potential worth of $12.6 trillion by 2030 because of the value it could bring to manufacturers worldwide.

Market Forces and Transparency as a Brand Differentiator

The Centers for Disease Control and Prevention estimates 9.9 million people experience foodborne illness every year. As a result, customer expectations for transparency and safety are rising. Norovirus was the most common, leading to the most hospitalizations, with salmonella causing the most deaths.

Brands as large as Walmart are using traceability to obtain a market advantage. It leveraged blockchain in its food supply ecosystem to track mango sales in U.S. stores and pork in Chinese locations. The system used digital certificates to validate authenticity and shortened provenance identification from seven days to 2.2 seconds.

The research was an important food chain traceability win for Walmart because customers had all but lost faith in romaine lettuce after a massive recall. The trial was so successful that Walmart will require leafy green suppliers to use the system.

Food sellers also differentiate themselves with traceability because it supports farmers’ livelihoods. Improving detectability and tracking locates the illness source faster, narrowing it down to one or a few origins. Governments can communicate these concerns with a recall, potentially pulling products before they hit shelves.

The swiftness preserves farmers’ reputations, who may struggle with the changing growing seasons. Food manufacturers that protect stakeholders will also see their public image shift in their favor. The initiative promotes them as thought leaders and essential collaborators in the volatile industry.

Operational Benefits of Integrating Traceability

Integrating traceability offers organizations benefits beyond compliance adherence. Every advantage reinforces positive brand perception, creating additional competitive advantages.

Traceability streamlines supply chains and recall processes. The technology and data visibility speed up the triage phase, identifying contaminated products faster. Employees spend less time investigating and more time communicating with authorities and stakeholders about what matters most.

Additionally, data-driven decision-making will create cost savings. Companies no longer carelessly throw away products because they have a more precise idea of what is contaminated due to improved inventory management and live stock updates.

Turning Compliance Into Competitive Advantage 

Food chain traceability is an organizational growth tool. Many view it as a regulatory hurdle, but it promotes accountability and transparency. Customers and clients will appreciate the commitment to public safety and quality, deepening their brand loyalty to the most dedicated. Corporations adopting traceability guidelines early will reap these benefits and more, scaling into new heights of profitability and efficiency.

Benefits of Proprietary Supplier Audits

By Nicole Keresztes James
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The food supply chain continues to face risks, including geopolitical impacts and climate change, which threaten food safety and quality from farm to fork. Proprietary supplier audits can be useful in evaluating how suppliers are establishing overarching safeguards for their products and processes, as well as promoting the development of a solid food safety culture across multiple links in the chain.

Proprietary supplier audits are typically seen as second- or third-party audits that are not officially benchmarked to Global Food Safety Initiative (GFSI) requirements. When used as second-party audits, auditors reference client-developed expectations to assess compliance of a supplier to that client. The expectations are often proprietary to a particular client and the auditors conducting those audits are doing so for the benefit of that client.

When used as third-party audits, auditors utilize a set of expectations that have been developed by audit firms or other organizations (i.e. not by a particular client). These expectations are proprietary to those firms, and the auditors conducting those audits are doing so for the benefit of the individual facility or company that has requested the audit.

Proprietary Supplier Audits in Practice

The purpose of proprietary supplier audits can vary in scope and be broad or specific in nature. For example, in the food manufacturing space, such audits could assess broad topics of food safety and quality across multiple categories of products and processing. Alternatively, proprietary supplier audits could focus very closely on specific concerns, like integrated pest management or environmental monitoring programs. Proprietary audits can also be used at different parts of the supply chain, from growers to product distribution.

Ideally, proprietary supplier audits are used to illustrate to a supplier and their customers where improvements are needed at a given facility to meet compliance to a set of expectations. Once these improvements are identified, the facility can proactively investigate the reasons for gaps in compliance and implement effective corrective actions to close the identified gaps. Proprietary supplier audits can also be used by clients interested in approving new suppliers to their network and/or for larger organizations to determine how closely facilities under their organization’s umbrella are adhering to food safety and quality expectations.

Proprietary supplier audits also can bring solid confidence into the supply chain as they are conducted by qualified, independent lead auditors with experience in the industry for which they are auditing (e.g., animal welfare audits are conducted by auditors with specific education, work and audit experience in animal handling and harvesting).

Key Benefits of Proprietary Supplier Audits

Proprietary supplier audits aid facilities in benchmarking competency against the expectations of the standard being audited. They can also assist larger clients and key customers in understanding their supplier base while building confidence in the suppliers that they have chosen to supply raw materials and finished products.

Proprietary audits can also be used as a lower-cost preparatory tool for an accredited benchmarked audit, such as one that is GFSI-benchmarked. The audits can also be hosted between certification visits to ensure that the facility’s systems are still working as required.

Speaking of options for lower-cost, proprietary audits also have the versatility and flexibility to meet clients’ and facilities’ needs in relation to modes of delivery. For example, in an increasingly digital world, calls for more options in virtual auditing are prevalent. Remotely conducted proprietary audit services are being embraced by the industry as both an introductory step for facilities new to food safety and quality audits, as well as an option for larger organizations to examine their suppliers in a more accessible virtual modality.

These supplier assurance remote desk audits can be delivered at a lower cost anywhere in the world where an internet connection is available. Key benefits to these types of audits include:

  • Understand expectations: Gain a clear understanding of what is required for a full on-site audit.
  • Save time and money: Reduce travel expenses and minimize downtime with remote audits.
  • Increase confidence: Build confidence when preparaing for a full on-site audit.
  • Affordability: Utilize an economical option to prepare for the next stage for a comprehensive audit.
  • Global reach: Audit suppliers anywhere in the world without the need for physical presence.

Audits of food safety expectations are typically developed with regulatory requirements at the most basic level. The auditors conducting these audits must be familiar with regulatory requirements such as the Food Safety Modernization Act (FSMA).

Additionally, proprietary supplier audits can support a variety of other topics beyond safety and quality in a further processing sense. For example, proprietary audits have a strong presence in the realm of animal welfare. For facilities that are further processors of protein materials, the proprietary audit expectations can look to ensure that these facilities are assessing their raw material suppliers (i.e., slaughter/harvest facilities and farms) for strong social accountability programs, such as ensuring the animals handled are able to enjoy the five freedoms of animal welfare. For facilities that do conduct slaughter/harvest processes and/or are the farms or feedlots in the supply chain leading up to harvest, the proprietary audits can directly assess those locations on the handling of the animals and ensure compliance with proper and humane practices.

Auditing Best Practices

Outside of working on a day-to-day basis to develop and continuously improve the programs at a facility that are the backbone of safe and quality products, a key preparation step for a proprietary supplier audit is to ensure that the audit standard is made available. Additionally, the standard must be understood by facility team members and cross-compared to facility programs. The cross-comparison can be done through internal and management audits. Internal audits are valuable tools in determining where compliance gaps exist prior to any audit. One of the common reasons for audit failures is a lack of awareness and understanding amongst facility team members about what the audit will cover and how compliance is determined.

Most importantly, a failed audit (and truthfully, all audits) can be seen as an opportunity to improve the systems at the facility. Unless it is a requirement of the standard being audited and/or there is a need to stop the processes happening during an audit to address a critical observation that jeopardizes health and safety, try not to prevent an audit visit from coming to its full conclusion. Ending an audit early may mean that other issues are not recognized; these other issues may continue to remain unrecognized until they become nonconformities at the next audit.

In the closing meeting of any audit, it is important to ensure that there is an understanding of the nonconformities that were found. This is key to the development of the most appropriate corrective actions. After the audit, collaboration of the team at the facility is imperative to discuss the results, create and implement the corrective actions, and monitor their effectiveness. Do not jump to scheduling a new audit until there is strong objective evidence to show that the corrective actions are working. If the team is uncertain about how to close the gaps identified during the failed audit, consider reaching out to external subject matter experts for assistance.

The Value of Proprietary Supplier Audits

Proprietary supplier audits can be incredibly valuable in bolstering food safety and preparing for future benchmarked audits. Working with an independent, third-party auditing organization such as NSF can help you to utilize a wide range of proprietary audit standards. Such standards can also be used and adapted by companies looking for a ready-made solution to conduct audits within their supplier partners.

Food processing and sanitation

Safety in the Details: Maintenance Practices That Make or Break Compliance

By Ainsley Lawrence
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Food processing and sanitation

Food production facilities constantly face scrutiny from regulatory bodies and consumers. While you might focus on visible sanitation protocols and equipment upkeep, subtle facility issues often remain undetected until they become critical compliance problems. Hard water deposits gradually compromise cleaning effectiveness, while hidden mold growth can quietly contaminate products despite thorough surface cleaning.

What seems like minor maintenance concerns can quickly become major regulatory violations, production shutdowns, and compromised food safety. When you recognize early warning signs of water quality issues and environmental contamination, you can address problems before they affect production or trigger compliance failures.

Water Quality and Its Impact on Food Safety

Water functions as both an ingredient and a cleaning agent throughout your food production facility. You might overlook how water composition affects everything from equipment performance to final product quality. Minerals in hard water create scale buildup inside pipes, valves, and machinery, reducing operational efficiency and creating ideal environments for bacterial growth in hard-to-clean crevices.

Scale accumulation on heating elements forces your equipment to work harder, shortening operational lifespans and increasing maintenance costs. Even more worrisome, mineral deposits can interfere with cleaning agents, reducing their effectiveness and potentially leaving surfaces inadequately sanitized despite proper chemical usage and cleaning protocols.

Food processing areas face particular challenges when hard water diminishes sanitizer effectiveness. Chemical reactions between minerals and cleaning agents can neutralize active compounds, leaving surfaces appearing clean while failing to meet microbial reduction standards. You might only discover resulting food safety risks during laboratory testing or regulatory inspections.

Selecting appropriate water treatment systems requires understanding your facility’s water quality challenges. Industrial water softeners protect critical equipment while ensuring cleaning chemicals perform at optimal levels. Softened water reduces chemical usage, improves cleaning efficacy, and helps maintain consistent product quality across production batches.

Mold Risks in Food Production Facilities

Mold contamination presents a persistent threat in your food production environment, yet early signs often remain unnoticed until problems escalate. Vigilant monitoring helps you prevent widespread contamination issues before they affect products or trigger regulatory concerns.

You should establish routine inspection protocols focusing on areas prone to moisture accumulation. Pay particular attention to loading docks, ceiling tiles near HVAC vents, wall joints, and drainage systems as common mold growth sites. Persistent musty odors often indicate hidden problems, even when visible mold remains absent. Train your staff to report such odors immediately so you can trigger thorough inspections of surrounding areas.

Visible water staining on walls, ceilings, and floors indicates current or past moisture issues requiring immediate investigation. Discolorations may appear minor but often signal more extensive problems behind surfaces. Humidity fluctuations, particularly in processing areas generating steam or requiring frequent cleaning, create ideal conditions for mold proliferation.

When you discover visible mold, implement immediate containment measures to prevent spore distribution throughout your facility. Signs you need professional mold remediation include recurring moisture issues, discovery of mold covering surfaces larger than 10 square feet, or mold in HVAC systems. Professional assessment determines contamination extent and appropriate removal methods to prevent cross-contamination during remediation.

Moisture control strategies provide long-term protection against mold development. Proper ventilation, strategic equipment placement to reduce condensation, and prompt repair of water leaks create environments less conducive to mold growth. Regular air quality testing complements your visual inspections by detecting elevated spore counts before visible growth appears.

Regulatory Compliance and Maintenance

Food safety regulations require comprehensive preventive controls addressing both known and potential hazards. Your maintenance programs are vital, meeting regulatory requirements by preventing physical, chemical, and biological contamination risks from facility infrastructure and equipment.

Regulatory inspections increasingly focus on maintenance documentation and implementation rather than written programs alone. Inspectors evaluate whether your maintenance practices effectively prevent contamination by examining repair records, preventive maintenance schedules, and corrective action documentation.

You benefit from integrating maintenance teams into food safety committees to ensure regulatory requirements inform maintenance priorities. Such collaboration helps your maintenance personnel understand how their work directly impacts compliance and product safety, encouraging more thorough documentation and follow-through on preventive measures.

Adding preventive maintenance takes thorough scheduling and verification:

  1. Catalog all equipment and facility components requiring regular maintenance.
  2. Document maintenance procedures specifically addressing food safety concerns.
  3. Establish verification steps confirming maintenance effectiveness.
  4. Create clear escalation protocols when maintenance issues impact food safety controls.
  5. Review and update maintenance procedures when equipment or processes change.

PCQI training supports preventive controls implementation by building cross-functional understanding of how maintenance practices affect food safety outcomes. Involving maintenance personnel in hazard analysis and preventive controls planning helps to identify overlooked maintenance concerns before they become critical regulatory issues.

Long-Term Maintenance Strategies for Sustainable Food Safety

Creating sustainable food safety requires moving from reactive maintenance to strategic facility management, addressing root causes of contamination risks. Preventive planning allows you to address small issues before they escalate into critical failures or regulatory violations.

Successful maintenance strategies integrate water quality management and environmental controls into standard operating procedures:

Quarterly water quality assessments help you track mineral content fluctuations and detect potential contamination issues before they affect production. Annual plumbing system evaluations identify areas prone to mineral buildup, requiring targeted descaling or component replacement.

Your environmental monitoring should include humidity tracking in processing areas, with documentation of seasonal fluctuations informing ventilation adjustments. Pay particular attention to HVAC maintenance schedules during seasonal transitions when temperature and humidity changes often reveal previously hidden issues.

Water treatment improvements yield multiple operational benefits. For instance, properly treated water reduces chemical usage during cleaning, extends equipment lifespan, and improves product consistency. You’ll typically encounter fewer maintenance calls for equipment malfunctions, particularly for steam-generating equipment and water-cooled systems.

Adding improvements to facilities requires a multifaceted strategy:

  1. Baseline current water quality through comprehensive testing.
  2. Identify critical control points where water quality impacts safety.
  3. Select appropriate treatment technologies based on specific contaminants.
  4. Implement monitoring procedures to verify treatment effectiveness.
  5. Train production staff on maintaining treatment systems.

You’ll find soft water integration improves cleaning effectiveness while reducing chemical consumption and labor requirements. Your product quality can benefit from more consistent flavor profiles and improved texture in water-intensive processing as well.

Renovation Considerations for Maintaining Food Safety

Facility renovations present both opportunities and risks for your food safety compliance. Thoughtful planning turns necessary updates into strategic improvements, driving long-term regulatory compliance, whereas poorly executed projects can introduce new contamination vulnerabilities despite significant capital investment.

Material selection plays a critical role in renovation success. Your food-contact surfaces require non-porous, easily cleanable materials resistant to cleaning chemicals and processing conditions. Even non-contact areas warrant careful material consideration since deteriorating building components can release particulates into production environments. Selecting proper sealants and gaskets prevents moisture intrusion into wall cavities and under equipment, eliminating potential mold growth sites.

Plumbing modifications demand particular scrutiny during renovation planning. Ensure pipe runs avoid areas where leaks could contaminate products or create hidden moisture problems. You can simplify future maintenance access by installing additional clean-outs and inspection ports during renovations, encouraging more frequent inspections and preventive maintenance. Water treatment system upgrades integrated during renovations improve overall facility operations while protecting new equipment investments.

Airflow patterns require careful engineering during facility modifications to prevent cross-contamination between production zones. Pressure differentials between areas with varying risk profiles help contain potential contaminants, which is particularly important when renovations connect previously separated processing areas. Food safety renovation planning should include airflow mapping before and after project completion.

Effective renovation planning requires:

  1. Conducting pre-renovation hazard analysis and identifying potential new risks.
  2. Establishing temporary controls to protect production during construction.
  3. Developing enhanced cleaning protocols for post-construction validation.
  4. Creating detailed documentation of infrastructure changes for future reference.
  5. Updating preventive maintenance programs and incorporating new components.

Post-renovation commissioning should include thorough environmental testing before resuming normal production and establishing new baselines for ongoing monitoring programs.

Final Thoughts

Success in food safety boils down to noticing the small details before they become big problems. Taking care of water quality and managing moisture in your facility creates a strong defense against contamination while keeping you on the right side of regulations. The payoff from this attentive approach is substantial – lower maintenance bills, more effective cleaning, and better product consistency. Instead of treating maintenance as separate from food safety, bringing these concerns together makes everything work better.

 

Raw chicken breast

How the Fieldale Farms Corporation Transformed Its Laboratory Operations with a Laboratory Information Management System (LIMS)

By Janet Smith, Kim Waters
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Raw chicken breast

For over 50 years, Fieldale Farms Corporation has built a reputation as one of the world’s largest independent poultry producers. Rooted in Northeast Georgia, this family-owned business remains committed to providing premium, healthy poultry products to customers in over 50 countries. With the ability to provide product packaging, fully cooked products, and other specialty items, Fieldale is a trusted one-stop source for quality poultry products.

Under the brand Springer Mountain Farms, Fieldale was the pioneer in raising poultry without the use of antibiotics as well as the first poultry producer to be American Humane Certified. With cutting-edge technology and a rigorous commitment to safety, Fieldale ensures every product meets the highest standards of quality for customers around the globe.

For years, the Fieldale Farms laboratory team depended on Microsoft Access databases and Excel spreadsheets to manage its laboratory data. While these tools served their purpose in the past, growing testing demands soon exposed their limitations.

One significant challenge was the lack of a comprehensive audit trail, which made it difficult to trace data changes and ensure accuracy. Also determining whether all samples were processed, testing was completed and protocols followed required extensive manual effort.

“We could not easily trace what method had been used and the technicians responsible without investing significant time and effort,” said Janet Smith, Manager of the Laboratory at Fieldale Farms.

The Fieldale lab required a modern software solution to simplify sample login, enhance tracking, ensure accurate result entry with a detailed audit trail, support strong QA/QC processes, and enable seamless electronic data transfer with laboratory instruments.

To tackle these challenges, Fieldale Farms’ ISO 17025 and USDA FSIS-accredited lab adopted a cloud-based LIMS. With this upgrade, the lab now enjoys full traceability. “Now, we can trace the sample all the way from the front door to final reporting knowing the technicians, methods, and equipment involved each step without a lot of paperwork review,” said Smith.

“With the LIMS, we achieve audit trail capabilities that were absent before,” said Smith. Any changes to validated and/or approved results will spawn an audit trail.  The LIMS audit trail stores the original result, the date and time stamp of the original result, the person that entered the original result and the new result, the date and time stamp of the new result, the user that made the change, and finally the new result. In addition, the LIMS will prompt the user to enter a reason for the change of the result.

Generating reports used to be a tedious time drain, diverting valuable time and resources from core laboratory functions. “Before, I often had to recreate reports for each “new/different” type of sample/customer when I didn’t have a template that was acceptable due to the reports being “static” – containing specific methods that often didn’t fit every scenario,” said Smith. The LIMS allows for dynamic reporting adaptable to different testing methods and client requirements. Reporting is now faster, more accurate, and far less frustrating.

Fieldale Farms Laboratory Team 

Another key benefit for the lab is instrument integration. “Parsing files from the instrument directly into the LIMS database is also a favorite.  No more data transcription errors and it is quick,” said Smith. The LIMS integrates seamlessly with the lab’s Leco Protein Analyzer, PCR, and NIR Spectrometer.

By adopting a modern, cloud-based LIMS solution, the lab eliminated the need for expensive hardware investments and avoided the hassle of setup and maintenance. With no need for specialized IT staff, the system runs smoothly with automatic updates, reducing staff workload and minimizing downtime. The result: improved productivity, streamlined operations, and uninterrupted lab performance.