From production to processing, distribution to preparation, each step of the food production chain presents a unique set of food safety challenges. One challenge, however, is universal across all facets of the food industry—pest control. Technologies may advance, supply chains shrink, and food trends evolve, but the pest control battle wages on, with rodents often leading the charge for the opposition.
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Explore This IssueApril/May 2018
Rodents eat or contaminate at least 20 percent of the world’s food each year. Their ability to contaminate on such a large scale is due in part to their “nibbling” habits, wherein they come into contact with far more than they actually consume. In addition, in just one year a rat can shed more than half a million body hairs, and a mouse can produce up to 18,000 fecal droppings. In that same year, a pair of rats can produce over 1,200 descendants. Within three years, that can grow to half a billion descendants! Rodents have been linked to asthma and transport fleas, lice, and ticks. The CDC also points out that they carry diseases including rat bite fever, hantavirus, leptospirosis, salmonellosis, murine typhus, and even the bubonic plague.
These are just a few of the disturbing statistics that highlight the importance of preventing infestations before they occur. Once rodents are inside, it is already too late. USDA Sanitation Performance Standards require that “establishments must have in place a pest management program to prevent the harborage and breeding of pests on the grounds and within establishment facilities. Pest control substances used must be safe and effective under the conditions of use and not be applied or stored in a manner that will result in the adulteration of product or the creation of insanitary conditions.”
The use of chemical rodenticides in the food industry is impractical, ineffective, and often highly dangerous. Exclusion—the method of creating physical barriers against rodents and pests to prevent them from entering a building in the first place—is preferred among industry professionals as the safest and most effective pest management strategy available. Fundamentally, it involves the elimination of cracks, crevices, and other spaces that allow rodents to gain entry. The CDC lists “sealing up holes inside and outside the home to prevent entry by rodents” as its number one suggestion in preventing rodent infestations. The New York City Department of Health and Mental Hygiene recommends “sealing all cracks, crevices, and holes in walls, cabinets, and doors” as its top guideline for controlling conditions that promote pests.
Rodent exclusion is fundamental to food safety. Keep the rodents out—plain and simple. Or is it? These tenacious pests are relentless in their pursuit of food and shelter. A mouse can squeeze through an opening the size of a dime, and a rat through an opening the size of a quarter. Rats have the ability to gnaw through plastic, wood, aluminum, brick, cement, and even lead. They can climb wires and rough surfaces, swim considerable distances and tread water for several days, making them a worthy opponent to say the least. But with a comprehensive exclusion plan and employee diligence, it is entirely possible to keep rodents at bay.
Safeguarding Your Building
Building access points are not difficult for rodents to find. The most obvious, and therefore the most critical to protect, are exterior doors. Without proper exclusion, rodents will literally walk through the door and compromise food safety. Personnel doors, garage doors, and loading dock doors are all at risk. Exterior doors should remain closed whenever possible, and sheet iron flashing should be installed at the base of wooden doors, which are susceptible to rodent gnawing.
The gap beneath exterior doors is a very common access point. Any clearance below the door must be smaller than 1/4 inch. It is a common misperception that standard rubber or bristle door sweeps are sufficient to protect this area. While rubber sweeps may help keep out the elements, they provide little to no protection against rodents. Even the smallest of rodents can gnaw through a bristle or rubber door sweep in the course of a single night. Metal brush seals pose a larger obstacle for rodents, but overtime they dent and deform leaving gaps that rodents can exploit to gain entry.
Specialized, rodent-proof door sweeps are perhaps the single most important exclusion tool available. Xcluder Rodent-Proof Door Sweeps, for example, feature reinforced rubber gaskets lined with Xcluder fill fabric—a blend of stainless steel and poly-fiber that has been tested and proven effective against rodents by USDA/APHIS. The reinforced edge prevents rodents from gnawing on the sides of door sweeps, and the fill fabric’s sharp, coarse fibers cannot be gnawed through by rodents. This type of specialized, rodent-proof product is fundamental to proper exclusion. Rodent-proof seals should be installed on all dock levelers, garage doors, and overhead doors. Vertical side seals are also important for dock doors because rodents will not stop at ground level attacks.
A simple method for testing door frame vulnerability is at night. Turn on the brightest light in the room or warehouse and step outside to see if any light is escaping around the door frame. If light can get out, pests can get in.
Additional rodent entry points that need protection include places where electrical, water, gas, sewer, and HVAC lines enter the building, beneath roofing tiles, and through small cracks in the foundation. The Mallis Handbook of Pest Control offers a practical set of exclusion guidelines for those tasked with protecting a building against rodents. Here are a few examples.
- Ventilator grills and windows should be protected with proper 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 materials.
- Large sidewalk cracks should be sealed, as these crevices allow rodents to access a restaurant’s foundation and 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.
- Ensure that cracked or broken roofing tiles are replaced as needed and utilize exclusion material to fill any voids.
The Right Tools for the Job
A comprehensive exclusion plan—one that identifies potential access points with a fine-tooth comb and constantly monitors for changes and weaknesses—is the most effective approach to protecting a building from invading rodents. A diligent plan, however, is only as effective as the barrier products installed. Caulk, mortar, and spray foam are occasionally recommended as exclusion tools. While appealing, given they are inexpensive and easy to install, these products offer little to no protection against rodents. A creature that can gnaw through lead pipes will certainly not be deterred by spray foam. Steel wool is another popular exclusion material. Though stronger than caulk and foam, steel wool faces rusting and decomposition over time and therefore requires regular replacement. Copper mesh, a more expensive solution, is effective against rodents when properly installed. However, this is not an easy task as a tight seal is difficult to secure, and the mesh often becomes loose over time. It is also a softer metal, lacking the sharp texture that discourages rodent gnawing.
Consider specialty exclusion products as a solution. Xcluder fill fabric compresses during installation to “spring back” once in place and creates a permanent seal, and the stainless-steel poly-fiber combination won’t rust or degrade over time. This type of proven, specialty product offers permanent protection against rodents, and the peace-of-mind that goes along with it.
Repellents and sonic devices should not be considered viable pest control solutions. Chemical repellents, designed to discourage rodent presence without harming them, are both unsafe for use in the food industry and ineffective overall. Repellents cannot be used near food products, and though the chemicals may cause rodents some amount of discomfort, the resulting distress is not nearly strong enough to deter them from their pursuit of food and shelter. Sonic devices producing ultrahigh or ultralow frequency sounds to deter rodents have been deemed ineffective by the scientific community.
The Importance of Sanitation for Pest Control
A discussion of exclusion best practices would be incomplete without mentioning the wider tenets of integrated pest management, including monitoring and sanitation. The following suggestions from The Mallis Handbook of Pest Control highlight the critical role of sanitation in the fight against rodents.
- Trash must be disposed in clean, tightly-sealed containers and stored as far from the building as possible. Trash removal should be frequent enough to ensure the containers are not a reliable rodent food source, ideally two or more times per week.
- Standing water attracts rodents, especially rats. Gutters should be free of debris and channel water away from the building. Leaky faucets, pipes, and air-conditioning units should be repaired or replaced. 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—boxes left on the ground are popular nesting grounds for rodents. Cabinet bases, storage shelving voids, and the tiny space behind appliances are also prime targets.
- Storage areas containing bagged or powdered food should be monitored consistently with stock rotated frequently. Whenever possible, store food products away from the walls to reduce the risk of contamination.
- Store food properly in sealed, rodent-proof containers made of metal or hard plastic. Any spills should be addressed as soon as possible.
- Regularly clean and sanitize appliances, equipment, food contact surfaces, and all floors to eliminate any sources of food for rodents. High volume areas where crumbs and trash are likely to accumulate must be cleaned frequently.
- Train employees to notice and report evidence of pests (e.g. rodent droppings in undisturbed areas), which should be addressed immediately.
The battle against rodents is not easily won. But a thorough, well-supported exclusion plan is the most effective tool in keeping rodents out, and absolutely critical in upholding food safety standards. Seek out pest management professionals who understand and support exclusion methods, and work with them to carefully identify and protect all building weaknesses. Do not underestimate the strength and resilience of these tenacious pests; take every precaution necessary and insist upon specialized, rodent-proof product solutions. Encourage all employees to report signs of rodent activity and remember that constant upkeep and monitoring are critical to long-term protection against rodents.
McFadden, the director of research and marketing for Xcluder Pest Control Products, 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. Reach him at firstname.lastname@example.org.