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From: Food Quality & Safety magazine, October/November 2006


Protect Food Safety by Saying No to Flies, Rodents and Cockroaches

by Zia Siddiqi, PhD, BCE

Food safety is always a hot issue in the food-manufacturing world. After all, the USDA’s Food Safety and Inspection Service (FSIS) undersecretary reports that 14 people die from foodborne illness every day in the United States. Foodborne illnesses may only be one aspect of food safety, but it’s an important one. That’s why food manufacturers go to great lengths to ensure the security of their products, including employing an effective pest management program. Most people realize that pests can contaminate food products and, at the simplest level, are very unsanitary. But few know that some of the most common pests in food manufacturing facilities – flies, rodents and cockroaches – carry a number of pathogens that can cause food borne illness.

Flies - The common house fly carries more than 100 pathogens, and all 12 species of flies carry E. coli, Salmonella and Shigella. Every time a fly lands, it transmits these pathogens to that surface. In fact, it is less sanitary for a fly to land on a food product than for a cockroach to walk across it.

Rodents - Rodents most often spread disease via their droppings. For example, house mice and Norway rats carry Salmonella in their intestinal tracts and transmit it through their droppings. Of course, rodents also can spread illnesses like Hantavirus and plague, though they pose a more ominous threat to employee health than to food safety.

Cockroaches - Cockroaches contract pathogens in the unsanitary conditions they frequent and carry them on the exterior of their bodies. They then introduce the organisms into new environments, causing food poisoning, asthma, diarrhea and dysentery.

To help prevent flies, rodents and cockroaches from threatening food safety, food manufacturers should employ integrated pest management (IPM) programs in their facilities. IPM programs emphasize multiple control methods to prevent pests, as opposed to a reliance on pesticides alone. Not only does IPM result in better management of pests, but by closely monitoring chemical treatments, it reduces the chance of contamination by pesticides and offers a long term solution.

Pest management is an issue because food manufacturing facilities offer pests food and water sources, shelter and comfortable temperatures. Pest management efforts will only be successful if pests cannot access these elements. Whether focusing on fly, rodent or cockroach management, an ongoing sanitation program must be instituted. A program that calls for the immediate clean-up of any product spills and regular waste management will inhibit pests from finding food and water in the facility.

Tell Flies to Buzz Off

With an ongoing sanitation program in place, manufacturers should next focus on techniques that discourage flies from ever approaching the building, keep them out if they get in and stop them from contaminating the product once inside.

It’s no revelation that lights attract flying insects. Manufacturers can use this attraction in their favor by mounting exterior fluorescent lights at least 100 feet from the building, thus drawing flies away from the facility. Sodium vapor lights can be used on the building, since they are not as attractive to flying insects.

If flies do approach the facility, #16 mesh screens, air curtains and positive airflow can help keep them out. Air curtains (plastic strip-doors) and positive airflow both work to reduce the flow of air from the outside and can literally push flying pests out. To check the airflow in their facilities, manufacturers should stand at an open door with a lighter. If the flame blows into the building, the airflow is negative; if it blows out, the airflow is positive.

Inside, manufacturers should work with professionals to place ultraviolet light traps near outside entrances and doors leading to processing operations. The ultraviolet light attracts flies to the devices, which then trap the pests on glue boards. Since third-party auditors monitor the placement of flying insect controls, it’s important to make sure they are used properly and cleaned regularly.

Don’t Let Rodents Play Dirty

Rodents may be associated with cold weather, but their prevention must be year-round. As with fly control, facility maintenance techniques are an integral part of rodent control and should be implemented along with a trapping and baiting program.

First and foremost, manufacturers should seal all unnecessary openings around the building’s exterior, concentrating on exterior points of entry – utility penetrations, doors, windows and rooftop HVAC units. Mice can squeeze through holes as small as a dime, and rats only need a hole the size of a quarter to enter a building.

Since rodents feel vulnerable out in the open, trimming back the vegetation from the building and installing a 30-inch wide gravel strip around the exterior can discourage them from ever approaching the facility.

In addition, third-party auditors require facilities to implement exterior baiting and interior trapping programs to control rodents. On the exterior, tamper-resistant bait stations should be placed at set intervals around the perimeter of the facility, while glue boards and traps should be strategically placed around the interior. Each third-party auditor has different requirements for the placement of these devices, so manufacturers should work with a pest management professional to ensure they adhere to the auditor’s guidelines.

Squash Cockroaches’ Dreams

The steps taken to prevent rodents from entering the building – sealing exterior openings and installing a gravel buffer – also will help prevent cockroach entry. Cockroaches can fit through openings as small as one-sixteenth of an inch, and the gravel strip acts as an obstacle to the crawling insects.

Inside the facility, glue boards and non-volatile baits can help control cockroaches. Glue boards trap the pests and are a useful device to help monitor the cockroach population’s activity over time.

Though non-volatile baits include chemicals, they are preferred over spray pesticides because they do not become airborne. Nevertheless, they should not be used in areas that could threaten food safety. Non-volatile gel baits can be injected into cracks and crevices, minimizing the likelihood that humans and products could come in contact with them.

The bottom line is whether they fly or scurry, pests are unwelcome in food manufacturing facilities. Manufacturers and pest management professionals should work together as part of an ongoing IPM partnership to prevent flies, rodents and cockroaches from posing threats to food safety. Commitment from both sides will help take pests out of the facility and food borne illness concerns off the table.

Dr. Zia Siddiqi is quality assurance director for Orkin, Inc. A Board Certified Entomologist with more than 30 years experience in the industry, Dr. Siddiqi is an acknowledged leader in the field of pest management. Reach him at



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