[Rodent Control] Rodenticide Use In Facilities

In the November 2003 issue of PCT, Mike Holcomb made an excellent case against the use of rodenticides for "maintenance baiting" in food facilities. I agree with Holcomb that rodenticides should not be used as a "routine," "maintenance" or "preventive" rodent control measure in food facilities. However, in cases of significant infestations of rodents in food facilities all IPM options need to be kept open.

A blanket prohibition of rodenticides in food facilities may cause more health and safety problems than it prevents. When confronted with a rodent infestation in a food facility, it is up to us as pest control professionals to select the methods and materials to eliminate the infestation as quickly and efficiently as possible with the least overall risk. The risks of contamination caused by rodents living in a food facility may outweigh the risks associated with using rodenticides to eliminate them.

First, for purposes of this article a "food facility" is defined as a place where food for humans is processed, stored, prepared, served or sold. This would include many different types of existing or potential customers, such as food-processing facilities, warehouses, restaurants and grocery stores.

WHY WORRY ABOUT THE RODENTS? The mere presence of rodents in a food facility is a violation of federal, state and local laws. For example, the Food and Drug Administration prohibits storing or processing food in places in which it may be contaminated by rodents.

Rodent "contamination" falls into two general categories. The first is referred to as filth. This is simply disgusting stuff no one wants in their food, whether it is harmful or not. Filth includes droppings, urine, hairs and dead rodent carcasses.

The second category of contamination includes the numerous diseases associated with rodents. Rodents could spread diseases in food facilities several ways. First, they may be infected with the disease and spread it in their urine and droppings. Or, they may travel in an area containing disease germs, such as a sewer, and then travel across food or food contact surfaces. Finally, they may carry parasites, which in turn may transmit disease to humans.

Other rodent-related food facility damage issues include fire hazards, liability concerns, tarnished images and the fear or stress caused by the presence of rodents.

ISSUES RELATED TO RODENTICIDES. Let’s start our discussion of rodenticide use to eliminate a rodent infestation in a food facility with the rodenticide label. Most rodenticide labels have the same (EPA required) language regarding use in food facilities: "Do not place bait in areas where there is a possibility of contaminating food or surfaces that come in direct contact with food."

Rodenticide contamination can occur in several ways:

• Rodents can "translocate" the material. That means they move it from one place to another, either intentionally (e.g., hoarding) or unintentionally (e.g., tracking).

• Air currents can blow rodenticide dust and small crumbs from one place to another.

• Vibrations can cause small particles of rodenticide or, in some cases, entire bait placements to fall from someplace high to a food product or food contact surface below.

• Humans can also translocate rodenticides. Well-intentioned employees may take it from where it was properly placed and put it where they saw rodents or signs of rodents. Disgruntled employees and vandals have been known to take properly placed rodenticide and deliberately contaminate a food product.

Two rodenticide applications are particularly risky and are discouraged.

• Tracking powder is not recommended in food facilities. By its nature, it is intended to be "tracked" (translocated), away from where it was applied, clinging to the feet and fur of the rodent. It is also difficult to remove the leftovers after the infestation is eliminated. It may also be scattered widely by air currents.

• Pellets are not recommended for indoor mouse control. Mice are notorious hoarders and will "translocate" pellets from a bait station to their nest site, which could be in a container of food or on a food contact surface. (However, pellets may be the best choice for placement in Norway rat burrows in soil under and around structures because blocks are often kicked out.)

PRECAUTIONS. Indoor applications of properly secured, block-type rodenticides in secured tamper-resistant bait stations may be the quickest, most efficient and most cost-effective way to eliminate an infestation of rodents in a food facility with the least overall risk. There are a number of factors to consider when deciding whether or not to use rodenticides in these sensitive accounts. For example:

• How extensive is the infestation? A few mice in a small area are probably best controlled with traps. A lot of mice scattered throughout the structure may warrant a rodenticide application.

• Who participates in the decision-
making process? As a minimum, participants should include account management, the pest control professional and his or her company management. In some accounts, such as USDA inspected facilities, inspectors must be included. And in some
situations third-party inspectors may be involved.

• Why are you considering using rodenticides? If there is only one reason, such as cost, you may want to reconsider other methods.

• Which rodenticides will you use and how will you apply it? Highly palatable products are designed to out-compete other food sources, such as spillage or food stored in another area.

• Which bait station will you use? Some bait stations can be locked so even adults will have difficulty opening them without a key. Furthermore, their lid hinges will hold up to hard use.

It is also important to think about where you would apply rodenticides:

• In areas in which all the food in an infested storage area is packaged in glass or metal containers, which would protect the food from contamination?

• Where would you apply rodenticides in an infested non-food area, which is isolated from food areas by walls or floors, such as boiler rooms, a crawlspace or the basement under a food facility?

• Where would you apply rodenticides in a process area during a "shut-down" when food is protected or removed and after which, contact surfaces are washed with detergent and water before start-up?

• Where would you apply rodenticides in voids or burrows?

• How will you keep control of rodenticides and recover them after the job is done?

SUMMARY. Don’t forget — rodents can re-infest an area quickly if preventive measures aren’t part of the elimination plan.

• Stress the importance of sanitation and harborage reduction to eliminate food, water and nesting places.

• Establish an effective perimeter trapping and baiting program to reduce the population around the facility.

• Promote rodent proofing to keep surviving rodents out.

• Employ internal trapping to capture those, which make it through your external defenses.

• Constantly re-evaluate and improve the program based on changing conditions and improvements in your knowledge of the facility.

Effective rodent control in food facilities is important to protect your customers and the public. When planning your rodent control program, use methods, which provide the lowest overall risk. Whenever rodenticides are used, take extraordinary precautions to prevent contamination of food and exposure to people and non-target animals. Also, take action to prevent re-infestation.

The author is the national technical support manager for Liphatech. He has been providing a variety of pest control services to food facilities for 30 years.