Pesticides may be used as part of a School IPM Program, but only when justified by scouting data and against an identified pest. Pesticides should not generally be applied to prevent pest infestations or if the nature and extent of the problem is unknown.
Pesticide toxicity is expressed as an LD50. The LD50 is usually given in terms of the milligrams of pesticide per kilogram of body weight required to kill half (50%) of the population. Because exposure to pesticide is usually constant, children are at the greatest risk of injury from pesticide exposure because of their low body weight. For this reason the overriding consideration in the use of pesticides in a school building or on school grounds must be the safety of students and staff. Do not apply pesticides in any classroom or area occupied by students or staff. Do not apply pesticides in areas used intermittently such as hallways, cafeterias, libraries, classrooms, etc during school hours. Always choose pesticide products that pose the least risk to people, particularly children, and apply those pesticides in a manner that minimizes exposure.
A pesticide is any chemical used to control pests. It may be called an insecticide, or a rodenticide, or a herbicide, depending on the target pest. Every pesticide is toxic and poses some risk to people and the environment. People exposed to excessive levels of a pesticide may suffer short-term or long-term health effects, depending on the toxicity of the pesticide and the degree of exposure.
People can be exposed to pesticides in several ways. The most common exposures occur during mixing and application.
People can also be exposed by entering treated areas too soon after application, before sprays have dried, dusts have settled out, or airborne residues have disappeared. People may be exposed to small but continuous doses if they work, live, or play in rooms with pesticide residues on rugs, furniture, food preparation surfaces, etc. or by inhaling volatile residues in the air. Small children may be exposed by touching, licking, or eating pesticide residues. Spills caused by accident or carelessness can cause dangerous pesticide exposures.
There are two documents that provide information on the safe and effective use of a particular pesticide product. The pesticide label states the chemical ingredients of the product, its relative toxicity and the pests it will control. It gives information on the amount of pesticide that should be applied, and how, when and where to apply it. The label also states what precautions the applicator must take, including the use of personal protective equipment when mixing and applying the product, when students, staff and other people may reenter the treated area, risks to other non-target organisms or the environment and how to minimize them and provides first aid information in case of accidental exposure.
The label is the law regarding the use of pesticides. All personnel applying pesticides and their supervisor(s) should read, understand, and follow the product label every time the pesticide is used.
The material safety data sheet, or MSDS, is a guide to the hazards of a pesticide. Although an MSDS has some of the same information that you can find on a pesticide label, it provides more technical details on:
These two documents, the pesticide label and the MSDS, are the primary sources for information on pesticide toxicity and how to use pesticides safely. The product label should be physically present at the site of pesticide application. The MSDS must be stored in a clearly marked file that is easily accessible at all times. Copies are frequently kept in pesticide logbooks as well.
Choosing the Right Pesticide
There are many factors to consider when choosing a pesticide for use in a school. You want it to be effective, of course. But in a school setting, particularly in rooms used by students, you want to be sure to choose pesticides that pose the least hazard to people. Some schools may limit your choices to a predetermined list of permitted pesticides. Whenever you get to choose a pesticide, be sure to consider the following characteristics:
Toxicity is a property, just like boiling point or color, used to describe a chemical. Toxicity is the capacity of a chemical to cause illness or injury. Pesticides are grouped into categories depending on how toxic they are to people. The more toxic pesticides cause injury at smaller doses and are therefore more hazardous to use. Special identifying words, called signal words, are printed in large letters on every pesticide label.
|DANGER means highly poisonous|
|WARNING means moderately toxic|
|CAUTION means slightly toxic or relatively nontoxic|
Signal words give you a relative measure of the toxicity of the pesticide concentrate or mix in the container. In other words it tells you how hazardous a pesticide is if it is swallowed, inhaled or absorbed straight out of its container or while mixing.
However, the toxicity of the end-use product (for example, the spray applied to a surface after being diluted) may be much less. Two pesticide products with the same signal word may pose different risks to people (such as students and teachers) in the treated area if, say, one is designed to be used full strength and the other to be mixed with water and diluted to a 1 per-cent solution.
As a general rule in schools, when choosing between similar pesticide products, choose the one whose end-use product (the material that is actually applied) is the least toxic to people.
This is the measure of how fast a pesticide vaporizes (turns into a gas) when exposed to the air. The lower the volatility, the less insecticide vapor in the air after treatment. Information about a pesticide's volatility can be found on the MSDS.
Sometimes a pesticide with high volatility is a good choice: when doing space treatments (fogging), for example. In most circumstances, however, it is best to choose a product with low volatility to minimize the level of airborne pesticide
Also consider how a pesticide is formulated, whether as a wettable powder, dust, emulsifiable concentrate, pressurized aerosol, bait, or other form, when. deciding which pesticide to use. For certain uses, the type of formulation is very important to the issue of safety. For example, insecticide dust, while a good choice for application into a wall void, would be a poor choice for application into a drop ceiling, where vibration might cause the dust to drift down on those below.
Applicators should choose low toxicity insecticides and formulations, and methods of application that reduce potential exposure, particularly in areas that students may enter. Products should have low volatility, be nonirritating, and specifically labeled for the site of application.
Use low-exposure application techniques. Most bait, crack and crevice, and void treatments put insecticides where cockroaches and many other indoor pests spend most of their time, and where children are least likely to contact the insecticide. These are also the techniques and sites least likely to generate indoor air residues.
Insecticide baits are among the best choices to reduce potential chemical exposure, since they are normally enclosed inside bait stations or else applied into cracks, crevices, and voids. They also have low volatility, meaning they do not easily vaporize or produce airborne residues.
Insecticide Bait Stations
Insect bait stations are available to control both cockroaches and ants. Their advantages for use inside schools are that the insecticide is enclosed inside a plastic station, the bait remains effective for long periods, and they are very easy to apply. A disadvantage is that they are often visible, and school children may collect and play with them. When used, they should be hidden inside cabinets, equipment, and other infested sites.
Baits do not attract cockroaches over long distances. To be effective, baits must be placed where cockroaches live or travel. (See Scouting) Since cockroaches prefer to travel along edges, place bait stations along edges and in corners. The more edges a bait station touches, the better it will work. Do not place bait stations in the middle of open areas. They will be ineffective.
Pastes, Gels, and Other Injectable Baits. There are now a variety of bait formulations for use inside cracks and crevices and in small spots inside hidden areas. Insecticide bait may be packaged inside tubes or syringes that you squeeze to apply, or designed to be applied by various types of bait "guns" or with a small spatula or putty knife. As a rule, baits are odorless, produce no vapors, have low human toxicity, and last for long periods.
To control German cockroaches, place spots or beads of bait in or near dark protected harborages or aggregation sites. Concentrate on edges, corners, cracks and crevices, and any place you see "spotting," feces, egg cases, or body parts of cockroaches. (See Scouting)
Crack and Crevice Treatment
Crack and crevice treatment is the application of small amounts of chemical directly into cracks and crevices where insects hide or enter. It is particularly effective against German cockroaches, which spend over 90 percent of their day hidden away in dark, quiet cracks, crevices, and voids.
You cannot do a proper crack and crevice treatment with a fan spray or pin stream nozzle on a compressed air sprayer. There is too much splash-back, too little penetration, and too many residues left outside. Instead, use an injector tip to inject the insecticide, whether a liquid, dust, or aerosol, into insect hiding places.
Void treatment is the application of insecticide into an empty space inside a wall or ceiling, behind a kickplate, inside a table leg, or in any other void. The application is usually done through an injector tip. Insecticide residues are out of the reach of people, and inside prime harborage sites for cockroaches, ants, and other pests.
There is some risk with void treatments that the insecticide may blow through the void and escape through other holes and "drift" into nontarget areas. Do not overapply or use too high a pressure when treating a void.
The application of an insecticide residue to a limited area, , usually not exceeding two square feet, is called a spot treatment. These areas may occur on floors, walls, and the undersides of equipment. Avoid spot treatments in sites where school children might contact the insecticide.
Other Types of Treatment
There are other types of treatment used to control pests. Some are not suitable for use in schools except in rare instances.
General or Broadcast Treatment is the application of insecticide to broad expanses of surfaces. Examples include the treatment of carpets and furniture for flea control and lawn insecticide applications. Avoid these types of treatments whenever possible, as they leave extensive areas of pesticide residue that might be contracted by students or staff. Careful scouting to precisely locate the pest population will most often permit using other treatment methods to gain the same result.
Perimeter treatment is an application of a barrier of insecticide to prevent the entry of pests. Typically, a liquid insecticide is applied in a coarse spray around the foundation treating soil, mulch, and lower vegetation from the foundation out 6-10 feet and up the foundation wall 2-3 feet. Additional treatment is made around doorways, windows, and other points of pest entry.
Perimeter treatments have the advantage of putting the insecticide outside to prevent pests from coming inside, thus reducing the need for controls in school rooms. But they have the disadvantage of putting a pesticide residue where small school children might contact it during play. Use perimeter treatments with care and only when other control methods prove ineffective.
Fogging is applying a fine aerosol mist of insecticide into the air. This method of treatment leaves insecticide residue on all surfaces of the room and its contents. Apply such treatments only as a last resort for emergency knockdown of large pest populations that are not responding to other control measures.
If general or perimeter treatment or fogging must be used, great care must be taken to prevent people from entering the treated area until safe to do so. The greatest risk comes from students or staff unaware of the pesticide application, entering the treated area during or immediately after application. All access to treated areas must be secured and marked until safe to use.
There are four major formulations of rodenticide used to control rodents: food baits, water baits, tracking powders, and fumigants.
Rodenticide baits combine a poison with a food bait attractive to rodents. Baits may be packaged in large bulk tubs, in individual place packs containing less than one ounce of bait, or anything in between.
Each rodenticide product has a different mode of action or method of killing the pest. Each formulation of rodenticide is intended for a unique control situation.
Always read and understand the label before using a rodenticide, no matter how many times you have used the product before. Labels change and products change and memory fades.
First and foremost, children, pets, wildlife, and domestic animals must be protected from eating the bait. All rodenticides have warnings on the label telling the applicator to place the bait "in locations not accessible to children, pets, wildlife, and domestic animals, or in tamper-resistant bait stations."
No one can give you a list of safe, inaccessible areas in and around a school. Whenever you are using a rodenticide bait in or near a school, ask yourself, "Is it possible for a child to get at the bait?" Do everything possible to prevent that from happening. Place baits deep inside active rodent burrows or inside tamper-resistant bait boxes.
A tamper-resistant bait station is designed so that a child or pet cannot get to the bait inside, but a rodent can. (Note: A bait tray is NOT a tamper-resistant bait station.) Tamper-resistant stations differ in the type and quality of construction, but they are usually metal or heavy plastic with a locking lid. Rat boxes are larger than those used for mice. Most are not considered truly tamper-resistant unless they can be secured to the floor, wall, or ground, and the lid can be locked into place.
Bait stations should be clearly labeled with a precautionary statement. Check them periodically to see if the bait is being taken and if the bait is fresh.
Place bait only where rodents are active as shown by droppings and other signs. Put bait stations outside near burrows and along travel routes. Put place packs or loose bait inside burrows. If a site is damp, such as inside sewers and storm drains, use paraffin bait blocks secured so that they cannot be dragged away or washed away.
Water baits are specially formulated rodenticides mixed with water. Various liquid dispensers are available. The best dispensers are custom designed for toxic water baits. Some tamper-resistant bait stations include compartments for water baits. Do not use standard "chick-founts" or other animal watering devices for liquid baits.
Water baits can be extremely effective, particularly against rats. However, water baits are attractive to other animals and to small children, and so can be particularly hazardous in a school environment.
Rodents groom themselves by licking their fur. Tracking powder makes use of this behavior. This formulation is simply a rodenticide combined with talc or powdery clay. It is applied into inaccessible areas where rats and mice live and travel. The powder sticks to their feet and fur, and is swallowed when the animals groom themselves. The major advantage to tracking powders is that they can kill rodents even when food and water are plentiful, or if rodents have become bait or trap-shy.
Tracking powders are usually applied with hand-operated bulb or bellows dusters. Apply the powder more heavily than you would apply an insecticide dust, but never more than 1/8-inch deep.
The rodenticide active ingredient in tracking powders is generally 5-40 times more concentrated than that in baits. Because of the risk to children, application of tracking powders at schools, when used at all, would be limited mostly to the inside of dry burrows outdoors. (Note: not all tracking powders are labeled for this use.)
If you need to use a tracking powder indoors, apply it inside wall voids, around rub marks, along pipe and conduit runs.
Never use tracking powders in suspended ceilings, around air ventilators, or near food or food preparation areas. The powder can become airborne and drift into nontarget areas.
Several fumigants are available for outdoor burrow fumigation. All fumigants are
extremely hazardous. They should only be used by those properly trained, licensed, and certified.
Information on our site was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.
The information in this material is for educational purposes. The recommendations contained are based on the best available knowledge at the time of printing. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension system does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.All agrochemicals/pesticides listed are registered for suggested uses in accordance with federal and Connecticut state laws and regulations as of the date of printing. If the information does not agree with current labeling, follow the label instructions. The label is the law.Warning! Agrochemicals/pesticides are dangerous. Read and follow all instructions and safety precautions on labels. Carefully handle and store agrochemicals/pesticides in originally labeled containers immediately in a safe manner and place. Contact the Connecticut Department of Environmental Protection for current regulations.The user of this information assumes all risks for personal injury or property damage.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Kirklyn M. Kerr, Director, Cooperative Extension System, The University of Connecticut, Storrs. The Connecticut Cooperative Extension System offers its programs to persons regardless of race, color, national origin, sex, age or disability and is an equal opportunity employer.