The pest management industry has always played a critical role in helping to protect the food supply chain of custody. A farm-to-fork approach is the current day mantra—a more involved, inclusive system of working with food-based companies and growers—to help ensure the food supply chain maintains a high level of product integrity. The introduction of the Food Safety Modernization Act (FSMA) aims to ensure the U.S. food supply is safe by shifting the focus from responding to contamination to preventing it. In order to prevent widespread food illness created by improper processing or sanitation practices, FMSA requires the pest management industry to better leverage their knowledge, program selections, educational pieces, including client trainings, along with treatment strategies to keep human, animal and pet food products safe for consumption.

Fumigation remains an important element of FSMA, and will successfully mitigate pest pressures when performed properly. Fumigation is a method of treatment for pest control purposes that relies on a gas to control or eliminate pests in a space. Fumigants are often applied to soil to control soil-infesting pests that can damage plant growth or crop yields, an example of just how early and important the use of fumigants can begin to protect the food supply chain. Critically important is the fumigation of primary grains, whether conducted post-harvest as a result of over-wintering, or a function of regulatory export on shipments bound for overseas. In so many cases, commodity values in bulk decline because the step of fumigation intervention was overlooked or performed after infestation and damage occurred.

As we move closer to the fork, we see product ingredients undergoing fumigation before the end product is finished, noting that some ingredient composition is more attractive to insect attack than others, but also protecting the finished product in cases where the evidence found warrants the use of gas, all in an effort to protect product integrity.

Why fumigation is an ideal pest control method

In some cases, fumigation work will be the most linear, effective way of treating a pest problem of great acuity.

The benefits of gas are many, but the results are unprecedented when proper fumigation principles are employed. One of the key characteristics of a fumigant is the ability to penetrate the infestation, or area of concern, if the area is remote or concealed, or in an area that conventional practices cannot touch, such as a vessel storing ingredients where strong penetration is required. With proper planning and adequate exposure periods, using a fumigant will generally create contact with the target pest.

The training and skill set of the fumigation lead will be critical in how areas are dosed and properly prepared. Considerations such as the use and placement of fans to equally distribute the gas and even consulting with the customer on product stock and inventory can make the facility more conducive to fumigation and enhance the end result.

When is fumigation necessary

Fumigation in some cases will be the first and only control method, and yet in other cases, it will be the last resort. When food safety, quality or other equivalent but timely measures cannot produce similar results, defaulting to fumigation is prudent.

Fumigation will be determined necessary for a variety of reasons, including:

• Safeguarding the health of consumers.
• The potential for economic losses resulting from client returns or lost business.
• Failed audits derived from pest pressures that may put existing relationships in peril.
• Product integrity issues that may make goods and commodities not conducive for sale.
• Regulatory pressure or consumer complaints.
• Allergens, filth or adulterated product that can lead to recalls or plant closings.
• A company’s culture that supports the position of food safety stewardship.

Types of fumigations

The types of fumigations can vary dramatically. In some cases, the professional fumigator will have to become both creative and strategic to influence outcomes while finding ways to accomplish work with economic advantages to the client. This work can run the gamut.

A facility fumigation, which the industry terms a structural or general fumigation, is where an entire building undergoes treatment. In a grain or storage setting, it may be isolated to some storage or grain bins, flat storage or even a bunker, especially in years where crop yield surpasses storage capacity. In many situations, only equipment and machinery will be placed under gas, called a “spot fumigation,” which can be done on regular intervals with the intention of controlling adult and larval stages, but without the cost and preparation of a general fumigation effort.

Other fumigations can occur in transport vehicles like railcars, which can remain under gas while in transit. Routinely, fumigation is conducted to containers for export purposes because of the wood packing material they contain. The International Standards for Phytosanitary Measures No. 15 (ISPM 15) was intended to prevent the international transport of insects or spread of disease, which could adversely impact ecosystems.

The fumigation process and methods

Preparation

Pest management experts must conduct a thorough assessment before any fumigation can be performed. This assessment is generally performed with key stakeholders to fully understand the scope of the problem, the viability and need for fumigation work and to help create a fumigation management plan (FMP), should the work be performed. It is during the assessment stage that the plan for fumigation first begins, including a survey of the target area or grounds, inspection of areas considered problematic such as tunnels, basement areas, drains and connections to other structures, including transfer or air-filled lines, review of facility or site drawings and a host of other things supported by the Federal product label.

Once a fumigation has been approved, it is the information learned during the site assessment that leverages the subject of “preparation.” All essential personnel from the company requesting the work and those from the fumigation and/or pest control company meet and discuss the preparation needed and review the fumigation management plan, a required document outlining every step of the fumigation to ensure it is both safe and effective.

What’s covered during the preparation phase

• Timelines for the job, including exposure period of the gas to target pressures, aeration times, which will lead to either re-entry of a structure or turning property back to the client, but only when gas levels are at or below the threshold limit value (TLV).
• Exchange of client and contractor contact information.
• Review of safety procedures, which may include hazard communication plans, confined space work and/or permits, use of powered or motorized vehicles, lock-out/tag-out work (LOTO) or access to the building, including disabling key cards if in place, or safe harboring “hard keys” from staff members.
• Guarding the structure to prevent unauthorized personnel from accessing the property.
• Confirming evacuation areas to confirm head count in times of distress or emergency.
• Understanding the workspace to ensure that no worker, contractor or civilian remains in the intended fumigated space or in a breathing zone if other types of work are being conducted.
• Knowledge of water main locations and other utility centers.
• Review of equipment that will need to be opened and cleaned prior to gas release.
• Contents that must be removed from the fumigation if in conflict with the Federal product label, where it is considered prohibited or when items may adversely react.
• Details on proper cleaning, removal of floor sweeping or product fines, purging of systems or anything that may negatively impact the penetration of the fumigant or success of the job.
• Conducting one-time or periodic walk throughs, depending on the work, to ensure that all punch list items have been successfully completed.

Physical “preparation” of the fumigation area is a project of laboring to make the site fumigation worthy. By definition, a site is worthy to be fumigated if it can hold gas for a specific period of time (exposure period), while maintaining a concentration of gas considered lethal to the target pest. In cases where gas egresses or diminishes faster than expected or a soft half-loss time, then the use of add-gas will be utilized to buffer concentrations back up to optimal levels.

Work that is often done to hold gas in an area of fumigation might include sealing vents, passive or powered dust collection systems or exterior filters originating from the inside. Essentially, any area that the gas, not air, can escape the intended space. It should be noted that no two fumigations are identical, and that all management plans and associated sealing efforts will be unique to the job at hand.

Monitoring

Monitoring gas concentrations of any job after release is one of the most critical aspects of any fumigation. The entire job hinges on the ability to hold gas, ensuring mortality will occur, often by taking measurements confirming that lethal doses remain present for the duration of the job. Pest management experts record and analyze readings or measurements to make determinations of the aggregate concentrations or snapshots of concentration, depending on the nature of the work, helping to confirm if the fumigation will be successful or whether additional gas must be used. Some gasses utilize a concentration and time criteria (CT), which must be met at the end of the fumigation.

Clearing and aeration

Clearing a space of gas is done through a process of aeration. This process can be performed many different ways, and is subject to the type of fumigation, the site and the equipment available for the fumigation or as part of the structure proper. When fumigating buildings, you will often force ventilate the structure using powered equipment to vacate gas or use on-site equipment to create “makeup” air. The introduction of air into a building helps to displace the fumigated air in the space, creating additional air movement. Bins and grain tanks are often equipped with fans and passive vents. Powered ventilators that expedite clearing of gas, trailers or containers often have higher CFM blowing fans placed internally pre-fumigation and are powered up inside the vehicle to create air movement upon opening the rear doors, allowing for quicker evacuation of the gas.

Eventually, all fumigated spaces must be checked, or cleared of gas to the established TLV indicated in the product labeling. It is imperative that no areas go unchecked. Fumigants by nature can gather in pockets or be trapped and can often build back up due to off-gassing once they enter commodities and then slowly diffuse back out.

Fumigators will use a variety of equipment that requires constant calibration to ensure accuracy of gas measurements. Clearing devices (devices used for determining safe re-entry or establishing if the TLV has been met) are generally specific to a unilateral gas and can pick up concentrations in the parts per million range (PPM). It is strongly suggested that backup detection and clearing instruments are on hand to support the final reading, as validating final readings are a must.

Conclusion

Fumigation treatments continue to be an important component of FSMA. This method will safely and effectively mitigate pest pressures and keep human, animal and pet food products safe for consumption. With the proper gas selection and a comprehensive assessment, a safe and effective fumigation can be performed, resulting in minimal risk of client return or lost business.