Editor’s Note: This article was adapted from Techletter, a biweekly publication from Pinto & Associates, Mechanicsville, Md. To subscribe, visit www.techletter.com, or call 301/884-3020.
Hospitals, nursing homes, hotels, restaurants and cafeterias all use special wheeled carts to transport food from kitchens to service areas or private rooms. These food carts range from simple insulated boxes designed to hold 40 to 120 individual plates, to mobile banquet or catering cabinets complete with electric or canned heat.
These rolling food carts literally can be “hot spots” for pests. Not only is a food cart attractive to insects such as cockroaches and ants because of food residues, but it also can serve as a transportation vehicle for other pests like bed bugs. Cracks, crevices and voids provide pest harborage, and insulation provides warmth. Carts tend to accumulate spilled food and might not get regular cleaning. They’re hard to keep track of since they are often simply wheeled into an out-of-the-way area until they’re needed again. But the biggest problem with food carts is that they will contain food at some time, which makes them a challenge to treat safely.
Here are some techniques that allow you to treat these troublesome spots safely and effectively:
Recordkeeping. Have all food carts at a facility numbered so you can treat them on a rotating basis. Inspect food carts at every visit to the facility, even if you have to do that on a rotating basis as well. Have a checklist to record sanitation, pest problems, inspection and treatment dates for each cart. Ask for a separate room or outdoor area where you can inspect and treat the carts. Be sure the air intake system doesn’t circulate pesticide vapors into other rooms. Keep in mind that the area where food carts are stored is likely to have the same pest problems and will require service.
Sealing and Cleaning. Use caulk to fill cracks and crevices on the carts. Check and replace worn gaskets around doors that allow pests inside. Vacuum the carts, including the compressor area in self-heating carts, to remove spilled food and pests.
Steam cleaning usually does not penetrate into insulated void areas on carts and might damage carts with heating elements. If the facility steam-cleans food carts, set up your rotation so that the carts are cleaned after your treatment if you use heat or cold treatment or CO2. But if you use insecticides, have the carts cleaned before your treatment.
Heat Treatment. Before initiating either heat or cold treatment, contact the food cart manufacturer to make sure that the cart can withstand the treatment planned. Heat treatment can be accomplished with a heat chamber or compartment like one used to treat furniture for bed bugs. One advantage to heat treatment is that you don’t have the condensation problems of cold treatment.
Heating will kill all stages of insects if the necessary temperature is reached and held for the required amount of time. Cockroaches, for example, are killed within 10 minutes at 140°F and in one hour at 115°F. All stages of bed bugs are killed in one hour at 113°F. You need to monitor the temperature, especially in inner void spaces and in insulated areas of the cart, to make sure you reach the necessary temperature.
Cold Treatment. You might be able to accomplish this easily by having food carts wheeled into a walk-in freezer. Cooling food carts to 5°F to 25°F for at least 4 hours will kill all stages of most pests. Be advised, though, that bed bug eggs are a bit resistant to cold and may require extended exposure. Suggest that the facility routinely store food carts overnight in a refrigerated area to slow down pest development. Cold treatment can stiffen greased areas of the cart, making it difficult to roll or can cause condensation problems with electrical equipment.
Carbon Dioxide Food carts can be treated with carbon dioxide in the form of dry ice. To control all stages of the German cockroach, you need 21 percent at 78°F for 24 hours. If you don’t have a fumigation chamber, you can wheel the cart into the middle of a large sheet of plastic. Crack 20 pounds of dry ice into three pieces and place them at different levels in the cart. Seal plastic seams with tape. Pull the plastic up and tie it at the top. Leave the cart sealed for 24 hours.
Insecticide. Badly infested food carts should be moved to the treatment room or to an outside area. Make sure the cart is cool and all heating elements are turned off. Drill small injection holes into the void areas of the cart. Inject a nonresidual spray into the holes using an injection tip. After treatment, close the injection holes with sheet metal screws and be sure that the cart is not used for 24 hours.
You can place insecticide bait stations on the underside of the food cart and in the compressor compartment. Avoid applying gel bait to a food cart where it might contact food surfaces or where heat could cause it to run onto food tray areas. Nonresidual contact sprays also can be applied when carts are disassembled for repairs or maintenance. Dusts are an option for sealed voids if there is no risk the dusts will contact food surfaces or food holding areas. Insecticide treatment of food carts is not recommended in health-care facilities.
The authors are well-known industry consultants and co-owners of Pinto & Associates.