As pest management professionals, you provide essential services to prevent and eradicate pest problems for a wide variety of clients. Many of your services are now based on the systematic process of Integrated Pest Management (IPM). When fully implemented, IPM places emphasis on customer education and cooperation, site inspection and pest monitoring, and non-chemical and chemical control solutions. Pesticides remain an important tool in IPM, but should be used only when and where needed.
Even when practicing IPM, clients are likely to have questions about the safety of pesticides. Clients want to protect their structures from pests, but also need assurance that the pesticides used will not harm their families, pets or co-workers. Technicians and their families also may have concerns about pesticides primarily because of the technician’s daily use and exposure to pesticides.
Professionals must have sufficient information on the pesticides they use so they are confident in handling the products. If technicians are unsure about the products they use, what kind of message about pesticide safety do you think is conveyed to clients? Well-trained technicians and others having direct contact with clients are in the best position to address client concerns about pesticide safety.
In this article, you will learn about the “hazard equation” and how it is used to explain the risk of pesticide use by combining the toxicity and potential exposure to pesticides. Six practical steps to significantly reduce pesticide exposure for technicians and clients are provided. While the information presented here applies to all pesticides, the primary focus is on insecticides.
What is the Hazard Equation? The hazard equation is this: Hazard = Toxicity X Exposure. “Hazard” is the potential for injury or danger of poisoning to occur when a pesticide is used. Everything we do has a certain level of hazard or risk associated with it. Pesticides are no different. They are designed to kill pests and even the least-toxic products have some level of risk. The hazard associated with pesticide use varies depending on the circumstances of its use.
“Toxicity” is the inherent ability of a chemical to cause injury. Toxicity is a fixed value and is based on the toxicity of the active ingredient in a pesticide formulation. It is measured in acute and chronic toxicity.
- Acute toxicity is the effect from a one-time exposure to relatively large amounts of a pesticide and symptoms are usually seen within a few minutes or hours of exposure. Toxicity is expressed as a lethal dose (LD50) or lethal concentration (LC50). The lower the LD50 or LC50 value, the more acutely toxic the pesticide. The U.S. Environmental Protection Agency uses acute toxicity to assign pesticides to toxicity categories and signal words (see the Table below).
- Chronic toxicity refers to the effect(s) of pesticides that occur after long-term, repeated exposures to relatively small amounts of pesticides. These effects are evaluated through multi-year laboratory studies. For toxicity information on a specific pesticide, refer to the product’s label and safety data sheet (SDS). If more information is needed, contact your distributor or product manufacturer.
The toxicity portion of the hazard equation is affected most by pesticide manufacturers. They develop new pesticides and maintain registrations for existing products. New pesticides must pass extensive testing that is required by EPA. The majority of the 120+ studies required by the EPA are safety related. For conventional pesticides, it may take as long as 8 to 10 years to complete the testing and to register new products. And every 15 years, as required by the Food Quality and Protection Act of 1996 (FQPA), existing pesticides must undergo re-evaluation to review scientific data developed after the pesticide’s initial registration. Despite the challenges of new pesticide development, manufacturers continue to provide products for the industry that are low in toxicity. More than 90 percent of insecticides available to professionals carry the CAUTION signal word and approximately another 2 percent are exempt from EPA registration.
“Exposure” is contact that occurs when pesticides are handled. Insecticides enter the body through skin, by mouth or by breathing. Dermal (or skin) exposure is the most common means of insecticide exposure. About 90 percent of all exposure is the result of skin contact. Oral exposure occurs when insecticide concentrate splashes into the mouth when mixing the insecticide, or when eating, drinking or smoking after application. Accidental oral exposure can be a problem when children have access to pesticides. Respiratory exposure generally accounts for less than 1 percent of the total exposure to insecticides by professionals. But because of the absorptive nature of the lungs, this is still an important route of exposure.
Six Steps. There are six steps to reduced insecticide exposure during and after application. They are as follows.
1. Read and follow all label directions and whenever possible select products with the CAUTION signal word or those exempt from registration. The directive to read and follow all label directions is frequently written or stated, but often not taken seriously. However, this is the first step in reducing pesticide exposure and is the foundation for actions that follow. When label directions are followed you can reduce your exposure and also protect clients and the environment.
2. Wear and care for personal protective equipment (PPE). Many labels list specific requirements for PPE. These requirements are based on the insecticide’s toxicity and potential for exposure. On other labels, the PPE is not listed. When using these products, follow company policy and your state’s regulatory requirements for PPE. In addition to having the safety equipment available for use, it’s essential that the equipment be clean and well maintained.
Here are some practical steps to reduce exposure:
- Keep your mouth closed while mixing.
- Never store pesticides in food containers.
- Wear clean clothes every day.
- Wear gloves and long sleeves whenever mixing or applying insecticides. Gloves also are recommended when applying baits for cockroach control.
- Wash with soap and water after use or immediately after accidental spills on yourself or clothing.
- Wear a respirator when mixing or applying insecticides, and when in an enclosed space, or spraying overhead.
- Use low spray pressure to reduce drift.
3. Select insecticide packaging that reduces exposure. Manufacturers offer packaging for insecticides that can greatly reduce exposure. For example, wettable powder formulations, when scooped from a jar, can be messy to handle, but when the powder is placed in water-soluble packets, exposure to the insecticide is greatly reduced during mixing. These packets have the added advantage of enabling more accurate mixing, thus helping professionals deliver the labeled rate to target sites. Another example is the tip “N” pour packaging that is now common for many liquid insecticide formulations. This packaging provides for accurate mixing and reduces exposure. Finally, self-contained bait stations (e.g., ant, cockroach and termite baits) reduce exposure during installation and also offer less exposure for clients.
4. Select the best formulation(s) for the job. The choice of insecticide formulation is often as important as choosing the active ingredient. Both exposure to the insecticide and effectiveness of the application can be affected by formulation. Careful inspection of the site and a good understanding of the pest problem are required before selecting the best formulation for the job. Visit with clients to determine if there are health-related issues or other concerns that may influence your product choices.
Fortunately, there are many effective formulations available to professionals. Of course, with multiple choices there also may be confusion. When using liquid sprays, you may select from formulations like suspension concentrates (SC), wettable powders (WP), capsule suspensions (CS), water-dispersible granules (WDG) and emulsifiable concentrates (EC). Insecticide baits have become an important formulation in pest management programs and include ready-to-use bait stations, gel baits, granular baits and liquid baits. Professionals also may choose to use aerosols, dusts or granular insecticides as part of their management programs.
Whatever formulations are selected, they must aid in getting the insecticide to the pest. This results in better product performance and generally less exposure to the insecticide.
For instance, when treating around the outside perimeter of structures, your treatment must often penetrate heavy mulch or dense vegetation to reach pests that live below this cover. In this situation, excessively high spray volumes are needed to reach pests with a liquid formulation. Therefore, granular insecticides or granular baits are often better choices because they are more dense and have a better chance to reach the target site.
In sensitive areas, bait formulations are generally the preferred formulation. Baits can be applied in cracks and crevices or applied in ready-to-use bait stations that completely enclose and protect the bait. Dust formulations, when applied properly, are an excellent choice for void treatments. In these sites, exposure is minimal to clients and the dust provides long-lasting protection against pests.
5. Maintain application equipment and use appropriate application techniques. Regular maintenance of application equipment can reduce the incidence of spills or leaks and unnecessary pesticide exposure. Proper equipment maintenance combined with calibration improves your delivery of insecticides and helps you follow label directions. Clients take notice of equipment that is clean and well maintained and this reinforces your professional image. Consult your distributor or equipment manufacturer for details on equipment maintenance and repair.
Application technique is another important factor that affects the amount of exposure to insecticides. There are several basic application methods widely used by professionals. These include fogging, broadcast application, soil treatment (primarily for subterranean termites), spot treatment, and crack-and-crevice or void application.
The trend in insecticide application is toward more targeted applications.
When making spot treatments, the treated area is limited to exposed areas that can be any dimension as long as it does not exceed 2 square feet. Crack-and-crevice applications further reduce exposure by eliminating insecticide residues on exposed surfaces. A common way to treat cracks and crevices with liquid formulations is with a pin stream application; however, for greater accuracy and reduced exposure, the application should be done using a crack-and-crevice straw.
Different application techniques are required for each insecticide formulation and if these are mastered exposure is greatly reduced. Attention to detail during application, even when no one is watching, is required of the professional.
6. Properly store and transport pesticides. We now have reached our final step in the discussion on reducing insecticide exposure. Accidents related to pesticide storage and transport can lead to serious injury. Professionals must:
- Store all pesticides in labeled containers;
- Lock the pesticide storage space on service vehicles, especially when unattended;
- Handle service kits with care and avoid access for children or pets.
Professional service offers an added value to clients by eliminating the need to store pesticides in their home or business. This, in itself, reduces potential pesticide exposure to building occupants, especially children and pets.
Summary. Professionals continue to rely on pesticides as an important tool to prevent and eradicate pest problems. With the use of pesticides comes the responsibility to select appropriate products and to apply them in a safe manner. This information, when fully understood and implemented, will help professionals communicate about the safe use of pesticides.
The “hazard equation” provides a big-picture look at the hazard or risk associated with pesticide use. It incorporates the toxicity of the pesticide and the potential exposure to the pesticide both during and after application. Also presented were six practical steps that will help professionals reduce exposure to pesticides. The individual who applies the pesticide is in the best position to reduce exposure. Please do what is right even when no one is looking.
The author is owner of Yosemite Environmental Services, Fresno, Calif. Contact him at firstname.lastname@example.org.
For more information
Braness, G.A. 2012. Your guide to pesticide labels and SDSs. PCT Magazine (June).
Braness, G.A. 2012. Choosing insecticides – tough decisions? PCT Magazine (Feb.)
Handbook of Pest Control – Mallis, 10th Ed.
Chapter 19: Insecticide & Pesticide Safety
Chapter 22: Equipment
Robinson, W.H. 2011. The Service Technician’s Field Manual, GIE Media.