Warnings as to Insecticides

The Safe Use of Insecticides

F. C. Bishopp, John L. Horsfall.

Insecticides kill insects because they affect a life process like respiration, digestion, circulation, and nerve reactions. A person also might experience some effect on his life processes if enough of the chemicals should get into the body by mouth, with or without food; through the nose, by breathing vapors or particles of dusts or liquids; or through the skin, by absorption.

Any person who plans to use an insecticide should inform himself therefore of its characteristics. What man, in his right mind, would attempt to fly an airplane without first learning how to do so?

Many sources give the characteristics of the various insecticides and directions for using them safely. The Department of Agriculture, county agricultural agents, most of the State agricultural colleges, agricultural experiment stations, and extension services can furnish, on request, printed matter that describes the characteristics of insecticides and the precautions to be observed in using them.

Another important source of information is the label on the container. Every user, before he opens the package, should read all the statements, directions, and warnings on it because it relates specifically to the material in the package. The instructions are there for good reason the user's safety.

The Insecticide, Fungicide, and Rodenticide Act requires that insecticides entering interstate commerce be registered and that labels on them carry information to safeguard the user and the public. The Food and Drug Administration, a unit of the Federal Security Agency, establishes tolerances; that is, levels of insecticidal residues that are safe on foods. Many States have laws requiring appropriate labels and controlling the application of pesticides by custom applicators.

INSECTICIDES differ in degree of toxicity the amount that would harm livestock or man : Man could tolerate pyrethrum and sulfur in rather large quantities, but small amounts of calcium arsenate or sodium fluoride would be dangerous.

Insecticides differ also in the way they act. Some (like nicotine sulfate) may be very poisonous, but show little cumulative effect. Others (like lead arsenate) are less acutely poisonous but build up in the system and produce ill effects if they are taken repeatedly into the body.

Some insecticides (like hexaethyl tetraphosphate) may be poisonous to insects and higher animals when first applied but lose their strength quickly. Others (like DDT) are less poisonous but persist for considerable periods.

Thus very poisonous materials must be handled and applied carefully. In the use of the less toxic but more persistent materials the hazards from residues must receive the major attention.

The danger always exists that a person may exercise great care when first using an insecticide and, experiencing no ill effects, may become more and more careless.

The home gardener who needs to control pests in his back yard would select insecticides from the group which need only a minimum of care in their use pyrethrum and rotenone, for example. The main precautions for him are to avoid getting the insecticides into the eyes or mouth or on the skin. Like all other insecticides, they should be stored in a place where children cannot touch them and where they cannot contaminate food.

A NONHAZARDOUS COMPOUND usually does not carry a poison label. If it includes a compound in solution with a propellant and is to be applied as a fine mist or if it is dissolved in deodorized kerosene and is to be applied as a spray to control household pests, a precaution on the label would state that contamination of foods should be avoided. If the spray contains a kerosene solvent, it should not be applied near an open flame. It is harmful if swallowed.

Insecticides with limited hazards are used commercially and many are recommended for the home gardener. A person who uses them should avoid breathing dust or spray mist, avoid contamination of feed and foodstuffs, keep the insecticides away from children and domestic animals, and wash himself thoroughly after using the materials.

The home gardener who uses a hand duster or sprayer, by observing the wind direction, can avoid breathing the dust or mist. If he happens to be particularly susceptible to inhalation of dusts of any kind he can obtain protection by using an inexpensive respirator of the type having a cloth filter pad. A handkerchief tied over the nose and mouth will give some protection.

Commercial operators who are exposed to inhalation of spray mists or dusts day after day should use a simple pad respirator. The warning not to contaminate feed and foodstuffs should make it obvious that this group of insecticides may leave residues on fruit and vegetables if they are used too near harvest.

Other insecticide formulations in this group may have vapors that should not be inhaled. They may have a slight hazard because of possible skin absorption or irritation. They may be harmful if swallowed.

If the label indicates a hazard from breathing the vapors, a respirator having a cartridge filter through which the air passes will furnish protection.

If danger of skin absorption is indicated on the label, contact with it should be avoided. Rubber gloves will be useful when handling it. Some solvents affect synthetic rubber quickly, and it is best to use gloves of natural rubber.

If the insecticide might harm the eyes, goggles should be worn. After spraying or dusting, clothing should be changed and the body carefully bathed. Clothing considerably contaminated should be laundered before being worn again.

Some of the insecticides of this class are used to control household pests. Even though the risk is not unduly great, the instructions on the labels should be followed.

HAZARDOUS COMPOUNDS may or may not bear the word "poison" on the label, depending on their concentration, but all are labeled to show that they are dangerous and may cause death if swallowed. Empty containers should be promptly destroyed or buried. They should never be left where children or domestic animals can get at them. Such insecticides should not be stored where contamination of food or feed can take place. The user should familiarize himself with the antidote mentioned on the label for accidental poisoning. Nearly all these insecticides, at the concentrations indicated, are used chiefly by commercial growers or those who apply insecticides on a contract basis.

Certain concentrated volatile insecticides are intended for mite control in chicken houses. Anyone using them should take special care to avoid breathing the vapors and letting them touch the skin.

Users of hazardous sprays should wash thoroughly and change clothing after working with the material for any length of time. A person who uses dusts day after day should use a good respirator and change the pads frequently.

Particular hazards are associated with the commercial use of organic phosphorus compounds. They are hazardous if swallowed, inhaled, or absorbed through the skin or eyes. Protective gloves, clothing, goggles, and a respirator with a special canister capable of absorbing the vapors should be worn. Users should wash thoroughly with soap and water after each day's operation.

AEROSOL BOMBS may contain pyrethrum, allethrin, or DDT as the insect-killing agent. The use of amounts indicated on the label creates no hazard, but it is best to close a treated room and remain outside for 15 minutes or more.

DDT solutions used in the form of thermal aerosols or fogs to control flies and mosquitoes over large areas cause practically no hazard to the operator or to -persons in the fogged area who might breathe the mists for a short time. The air dilution and short exposure are protective factors. To remain in such aerosol clouds for long periods is inadvisable, however.

Aerosols are sometimes used to destroy insects on vegetation. The insecticide is dissolved in an organic solvent in the aerosol formulation. This may present some hazard from skin absorption, and care should be taken when handling such solutions. Gloves of natural rubber should be worn. Hands and skin should be washed if there is contact with the solution. Goggles and a respirator should be worn to avoid breathing the fumes.

Organic phosphorus insecticides are not recommended for use in these fogs for outdoor-area treatment. Aerosols in which they are combined with a propellant are released from cylinders for controlling greenhouse pests. The operator should wear protective clothing, gloves, and a face mask equipped with a universal-type N-canister. Treated greenhouses should be posted and locked, and no one should enter them until they are thoroughly aired.

With the increased use of insecticides since 1945, however, more precautions have become necessary to protect pilots and flagmen as well as other people, livestock, and wildlife in the treated and adjacent areas.

SPECIAL CARE must be observed when pilots or helpers apply sprays or dusts containing organic phosphorus compounds. It is necessary to avoid breathing the dust, vapor, or spray mist and to avoid skin contact. Loaders must wear a full-face mask provided with a universal-type N-canister, because of their severe exposure to the insecticide concentrates. Pilots and helpers should wear respirators with a fume-type filter and chemical-absorbing cartridge. Freshly laundered, waterproof, or protective clothing that covers all exposed skin surfaces should be worn. The clothing should be changed daily. The equipment should be checked before loading to make sure all connections are tight and the system is functioning properly. The pilot should lay out his course so as to avoid flying back through an insecticide cloud.