Reduce Rodent Risk Using Exclusion Best Practices

Some of the most notorious pests threatening the food industry are rodents. Beyond feeding on and contaminating inventory, mice and rats can cause significant structural and equipment damage, pose a fire risk from chewed wires and, of course, pose serious health risks to your customers and employees.

Drew McFaddenDrew McFadden

The “Sanitary Operations” section (21 CFR 117.35(c)) of Good Manufacturing Practices (cGMPs) reads, “Pests must not be allowed in any area of a food plant” and later that “Effective measures must be taken to exclude pests from the manufacturing, processing, packing, and holding areas and to protect against the contamination of food on the premises by pests.”

As the FDA Food Safety Modernization Act Preventive Controls for Human Food rule says these cGMPs are requirements, not guidance, it’s no secret that a comprehensive and sustainable pest exclusion plan is vital for any food facility manager.

Arguably, some of the most notorious pests threatening the food industry are rodents. Beyond feeding on and contaminating inventory (resulting in disposal or rejected shipments), mice and rats can cause significant structural and equipment damage, pose a fire risk from chewed wires and, of course, pose serious health risks to your customers and employees. Per the Centers for Disease Control and Prevention, rodents are known to carry and spread more than 35 diseases worldwide, including Salmonella and Hantavirus. 

Yes, managing a comprehensive rodent control program requires a thorough understanding of the issues involved, as well as a high level of commitment to success. But the effort of proactively controlling rodents is miniscule compared to the potential losses that can occur due to an infestation. 

It’s likely you are already familiar with the idea of Integrated Pest Management (IPM) and the concept of exclusion as the preferred approach to rodent control. The IPM model is a comprehensive approach that includes monitoring, sanitation, exclusion and, only if absolutely necessary, the application of rodenticides. Dr. Robert Corrigan, Rodentology PhD and leading industry expert and proponent of the IPM approach, confirms that “Rodenticides should be considered as a last resort, especially around food stores, food serving establishments and any shop that the public frequents.” 

According to The Mallis Handbook of Pest Control, the leading pest control industry guide, the combination of exclusion and sanitation provides the best long-term and cost-effective component of any rodent IPM program. Fundamentally, exclusion involves the elimination of cracks, crevices and other spaces to prevent pests from entering a building. Rodents can squeeze through an opening as small as 1/4-inch, which means access points are not hard for them to find. 

The most common rodent entry points include: exterior doors, garage and loading dock doors, air vents and at points where electrical, water, gas, sewer and HVAC lines enter the building. Rats and mice also gain entry through small cracks in the foundation, beneath loose roofing tiles and by gnawing through inadequate door sweeps or dock seals.

To address these weaknesses, here are a few exclusion and sanitation best practices highlighted in the most recent Edition of The Mallis Handbook of Pest Control:

  • Safeguard your doors. Wooden doors are continuously vulnerable to the gnawing of rats. Sheet iron flashing should be installed surrounding the door, and any clearance below the door must be smaller than 3/8-inch. All doors should remain closed when not in use and be fitted with proven, specialized rodent-proof door sweeps.
  • Ventilator grills and windows should be protected with proper and proven exclusion materials, ensuring any voids or cracks are filled.
  • Defective drain pipes provide a transportation pipeline for rodents. A perforated metal cover should be cemented over the drain pipe, and any small openings surrounding the drain where it enters the building should be patched or filled with proven exclusion material.
  • Large sidewalk cracks should be sealed as these crevices allow rodents to access a building's foundation, enabling them to more easily search for entry points. Foundation walls can be protected with barriers of metal, concrete or brick around and below the foundation.
  • Circular rat guards should be placed around all vertical wires and pipes, as in addition to squeezing through miniscule openings, rats and mice can climb wires and rough surfaces with relative ease.
  • Ensure that cracked or broken roofing tiles are identified and replaced in a timely manner, and utilize proven exclusion material to fill any voids.
  • Keep the exterior of the building as clean as possible. Trash should be disposed of in clean, tightly-sealed containers and stored as far from the building as possible. Trash removal should be frequent enough (at least twice a week) to ensure the containers are not a reliable rodent food source.
  • Building roofs and gutters should always be free of debris and channel water away from the building, as standing water attracts rodents. Leaky faucets, pipes and air-conditioning units should be repaired or replaced quickly. Water should not be left standing in sinks overnight, and storage rooms and basements should be dry and well-ventilated. 
  • Avoid clutter as much as possible (both inside and outside). Boxes left on the ground are popular nesting places for rodents. Cabinet bases, storage shelving voids and the tiny space behind machinery are also prime nesting areas.
  • Employees should be trained to notice and incentivized to report evidence of pests (e.g. rodent droppings in undisturbed areas). It’s important that pest problems be identified and addressed as quickly as possible.

Remember, too, that windows break, pipes rust and concrete deteriorates, creating new rodent access points at any time. Successful exclusion requires ongoing vigilance and upkeep. And, of course, a comprehensive and well-supported exclusion plan is only as effective as the barrier products installed. Here are a few examples for consideration:

  • Door Sweeps & Loading Dock Seals: As is often the case, you get what you pay for. A standard rubber door sweep or loading dock seal won't last the night against a determined mouse or rat. Insist on door sweeps and seals that are built especially for deterring rodents and have been proven effective.
  • Eliminating Holes, Cracks and Crevices: Caulk, mortar and spray foam products will offer almost zero protection against gnawing rodents. Rats have been known to eat through concrete when determined enough, so it’s vital that any opening larger than the width of a pencil be sealed with proven rodent exclusion material.

According to Dr. Austin Frishman, world-renowned entomologist and pest management consultant, “the success of pest management in the food industry is not a complicated or hidden secret. We know what it requires. Eliminating conducive conditions before they occur prevents problems from occurring. Within the last few years, new rodent proofing material has become available to keep pests out even after hurricanes. Properly installed, these specialized door sweeps and fiber fabrics in wall and floor cracks and voids work wonders to keep pests out.”

It’s cliché but true — an ounce of prevention is worth a pound of cure. IPM practices involving exclusion and sanitation are simply the best prevention money can buy. Work with pest management professionals who understand and support exclusion methods, helping you implement and sustain a comprehensive plan that protects both interior and exterior weaknesses. Reiterate to employees the importance of sanitation and facility monitoring for signs of rodent activity. Finally, rely on proven exclusion products and solutions to protect your customers and your business. 

About the author

Drew McFadden is the Director of Research and Marketing for Xcluder Pest Control Products, the preferred exclusion brand used by pest management professionals around the world.  Drew has been serving the commercial and residential pest exclusion industry for many years, touching all levels of the food supply chain from production to retail. 

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