By Les Baucum|November 1, 2012

For obvious reasons, pesticides are designed to kill, repel or otherwise control unwanted pests, and in most cases these pesticides are designed to kill the targeted pest. In many ways, living organisms are not all that different from one another, and something that is toxic to one species may also be toxic to other, non-targeted organisms. For example, insects, rodents and humans have similarities in their nervous, circulatory and respiratory systems, all systems that are targeted by different pesticides; and it is these similarities that are the reason some pesticides can cause harmful effects in humans.

Pesticides can cause both long-term and short-term effects on your health.  Be sure to refer to the signal word located on the products label as well as to the information contained in the “Hazards to Humans and domestic Animals” section found on all labels to learn more about human toxicity concerns. Keep in mind that in addition to the physical and chemical toxicity concerns many pesticides pose a risk by being explosive or combustible.  Also, be sure to refer to the products material data safety sheet (MSDS) for more information on potential hazards.

How Pesticides Enter the Body (Exposure)

When a pesticide is taken into the body, we refer to this as “Exposure”; pesticides can enter the body orally (through the mouth), through the eyes (ocular), dermally (through the skin) or by inhalation (through the nose and respiratory system).

Oral Exposure:  It is possible for oral exposure to a pesticide to occur accidently, but it is much more likely to occur as a result of carelessness; such as blowing out a clogged nozzle with your mouth, smoking eating or going to the restroom without washing your hands after using a pesticide, or even splashing concentrated pesticides while mixing. The seriousness of this exposure would depend not only on the oral toxicity of the product, but also the amount swallowed. Children are frequently the victims of accidental oral exposure thru improperly stored pesticides in the home, such as rat baits or when pesticides have been taken from the original labeled container and put into an unlabeled bottle or food container. This is not only illegal but children often associate these containers with their original products. You should also mark all pesticide measuring cups and containers to ensure that they are not used for water, drink or food.

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Dermal Exposure:  Dermal, or skin, exposure accounts for about 97% of the exposure pesticide users receive from non-fumigant pesticides. Dermal exposure can occur any time a pesticide is mixed, applied, from contact with pesticide residues on treated surfaces, contaminated personal protective equipment (PPE), or anytime pesticides are otherwise handled, and these exposures often go undetected. Although the rates of absorption through the skin are different for different parts of the body, it is important to remember that the absorption of the pesticide continues to take place as long as the pesticide is in contact with the skin. The seriousness of a dermal exposure to pesticides depends upon:

• The dermal toxicity of the pesticide to which you were exposed.
• The rate of absorption of the pesticide through the skin.
• The size of the skin area contaminated by the pesticide.
• The length of time the pesticide is in contact with the skin.
• The amount of pesticide on the skin.
• Additionally pesticide formulations can vary in their ability to penetrate the skin; in general water soluble liquids or powders, wettable powders, dusts and granular products do not penetrate the skin easily, while oil or solvent based pesticides such as emulsifiable concentrates are readily absorbed.

Pesticide Safety Pointers ctd.

Inhalation Exposure:  Results from breathing pesticide vapors, dust, or spray particles. Inhalation exposure can occur by breathing smoke from burning pesticide containers, breathing fumes from pesticides while applying them without PPE, inhaling fumes while mixing and pouring pesticides and smoking tobacco products containing pesticide residues.  Once breathed into the lungs, pesticides can enter the bloodstream very rapidly, resulting in damage to various body organs.

Ocular Exposure: Blood vessels are very close to the surface of the eye, allowing pesticides to be easily absorbed into the bloodstream.  Under certain conditions and with certain pesticides absorption through the eyes can be significant and particularly hazardous. Eyes are very sensitive to many pesticides and for their size they can absorb large amount of pesticides.  In addition to concern of the absorption rate, some chemicals are corrosive and can cause physical damage to the eye leading to severe eye damage or even blindness.  Serious eye exposure can result from airborne dusts or particles, splashes, spills, broken hoses, spray mists, or from rubbing the eyes with contaminated hands or clothing.

Toxicity refers to the ability of a poison to produce adverse effects by altering normal body functions; these effects can range from slight symptoms, such as headaches, to severe symptoms like coma, convulsions or death.  Most toxic effects are reversible if treated soon after exposure; however some poisons do cause irreversible or permanent damage.

All new pesticides are tested to establish the type of toxicity as well as the exposure level necessary to produce an adverse reaction. The level of testing required is quite extensive, and therefore expensive. Toxicity testing is done with various animals and plants and the results of these tests are used to predict the safety of the new pesticide to humans. Toxicity tests are based on two premises. The first is that information about toxicity in animals can be used to predict toxicity in humans; and the second is that by exposing animals to large doses of pesticides for short periods of time, we can predict human toxicity from exposure to small doses for long periods of time.  While both premises have been questioned, experience has shown that toxicity data collected from multiple species of animals is a better indicator than data collected from a single species.

Toxicity is divided into two types, acute toxicity or chronic toxicity; this is based on the number of exposures to a poison and the time it takes for toxic symptoms to develop. Acute toxicity is due to short-term exposure and happens within a short period of time.  Chronic toxicity is due to repeated or long-term exposure to a pesticide and happens over a longer period.

Acute Toxicity, refers to the ability of a pesticide to do systemic damage as a result of a one-time exposure to a chemical (pesticide). A pesticide with a high acute toxicity may be deadly if even a small amount is absorbed. The signal words on the label of a pesticide are based on the acute toxicity of that pesticide and may be measured as acute oral, acute dermal or acute inhalation.

Acute inhalation toxicity is generally measured by the lethal concentration of the pesticide; concentration is used instead of dose because the amount of pesticide inhaled from the air is being measured. Inhalation toxicity is expressed as LC₅₀ and is measured in milligrams per liter (m/l).

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Delayed effects are illnesses or injuries that do not appear immediately after exposure to a pesticide.  Symptoms may be delayed for weeks, months or even years and can depend on the pesticide exposed to, the extent and route of the exposure and how often you were exposed.  Under “Precautionary Statements”, the label will usually state any possible delayed effects that the pesticide may cause and how to avoid exposures leading to these effects.  Delayed effects can be caused by either an acute or chronic exposure to a pesticide.

Allergic effects are harmful effects that some people develop as a reaction to substances that do not cause the same reaction in most other people, such as poison ivy causing a skin rash. Allergic reactions typically do not occur during the exposure to a substance, but generally develop after subsequent exposures; this process is referred to as sensitization.  Some people can become sensitized to certain pesticides and develop severe allergy-like responses, including:

• Systemic effects, such as asthma or life-threatening shock
• Skin irritation such as rash, blisters or open sores
• Eye and nose irritation such as itchy, watery eyes and sneezing

Unfortunately there is no way to tell which people may develop to allergies to which pesticides.

First Aid for Pesticide Poisoning

If you or any of your fellow employees have unusual or unexplained symptoms that develop within 24 hours of being exposed to a pesticide, you should seek medical advice immediately. Be alert for the early symptoms of pesticide poisoning, recognizing these symptoms early and providing first aid may save a life or prevent a permanent injury. When seeking medical advice make sure to take the pesticide label with you, the attending physician will need to know the pesticides ingredients to determine the proper course of treatment. Remember that certain symptoms are not always the results of pesticide exposure. Illnesses such as the flu, heat exhaustion or heat stroke, pneumonia, asthma, respiratory or intestinal infections, or even a hangover can cause similar symptoms. Contact with certain plants can produce skin affects like those resulting from pesticide exposure. Even with all of this, when symptoms do appear after you have been exposed to a pesticide, it is always better to be cautious and seek medical attention immediately.

Basic First Aid is the initial effort to help a victim while medical help is on the way. Before you call for medical assistance, make sure they are breathing and that they are no longer being exposed to the pesticide. Be careful to protect yourself from pesticide exposure prior to and while giving assistance. Wear the appropriate PPE, including a respirator before assisting someone in an enclosed area. If the victim is not breathing apply artificial respiration. Immediate action can be a matter of life or death. The product label is the primary source of information; follow first aid instructions carefully. Remember that first aid is only the first response, it is very important to get the victim to a hospital as soon as possible. The following are a few key points to remember when administering first aid following a pesticide exposure:

• If oral or dermal exposure has occurred, you will need to dilute the pesticide with a clean source of water to prevent absorption.
• Never try to give anything by mouth to an unconscious person.
• If inhalation exposure occurs, get the victim to fresh air immediately.
• Become familiar with the proper techniques of artificial respiration.
• If there is any possibility of first responders being directly exposed to a pesticide, be sure to wear appropriate PPE.

Pesticide Safety Pointers ctd.

Clothing or PPE that is contaminated with toxic pesticides should be properly disposed of; most pesticides are regulated as solid waste and can therefore be disposed of as solid waste (trash). If clothing is contaminated by a pesticide regulated hazardous waste as the result of a spill or leak then it is considered hazardous waste and must be disposed of accordingly; however if the clothing becomes contaminated as a result of a normal, legal application of the pesticide then it is considered normal solid waste.

If you are exposed to a pesticide on the skin, you should:

• Always have an adequate supply of clean water anytime that skin exposure is possible.Remove all contaminated clothing immediately.
• Wash the affected area with water and soap, then rinse well; avoid harsh scrubbing which can enhance pesticide absorption.
• Gently dry the affected area and wrap in a loose cloth or blanket, if necessary.
• If the skin has chemical burns, cover the area loosely with a clean, soft cloth.  Avoid using ointments, greases, powders and other medications unless instructed to do so by medical personnel.

Pesticides in the eye; because the eyes readily absorb material that gets into them, fast action is required:

• Hold the eyelid open and immediately begin gently washing the eye with clean water; do not use chemicals in the wash-water unless instructed to do so by medical personnel.
• Drip the water across the eye, not directly into the eye.
• Continuously rinse the eye for 15 minutes.
• If only one eye is involved be careful not to contaminate the other eye.
• Flush under the eyelids to remove any trapped chemical.
• Cover the eye with a clean piece of cloth and immediately seek medical attention.

The basic first aid procedure for someone who has inhaled a pesticide is to get them to fresh air:

• Immediately carry the victim to fresh air; do not allow them to walk.
• Do not attempt to rescue someone who is in an enclosed, contaminated area unless you are wearing appropriate PPE.
• If other people are in the area, warn them of the danger.
• Have the victim lie down and loosen their clothing.
• Keep the victim warm and relaxed.
• If the victim is convulsing, protect their head and pay attention to ensure that breathing continues.
• Keep the victims chin up to ensure that air passages are open for breathing.
• If breathing stops or is irregular, give artificial respiration.

Pesticide in the mouth or swallowed:  If pesticide has gotten in the mouth but has not been swallowed, rinse the mouth thoroughly with plenty of water and then give the victim large amounts (up to 1 quart) of milk or water to drink. If the pesticide has been swallowed, one of the most critical first aid decisions is whether to induce vomiting or not. You should induce vomiting only if the label instructs you to do so; several pesticides can cause more harm when vomited up than if they remain in your stomach. Never induce vomiting if the victim:

• Is unconscious or having convulsions.
• Has swallowed a corrosive poison, such as a strong alkali or acid; which can burn the throat and mouth as much or more severely coming up as it did going down.
• Has swallowed an emulsifiable concentrate or oil solution product, which is dissolved in petroleum solvents. Emulsifiable concentrates and oil solutions can be fatal if aspirated into the lungs during vomiting.

If you have to induce vomiting:

• Make sure the victim is leaning forward or lying on his side to prevent vomit from entering the lungs.
• First give the victim at least 2 glasses of water to dilute the; do not use carbonated beverages.
• To induce vomiting, put your finger or the blunt end of a spoon at the back of the throat; do not use anything sharp or pointed.
• Collect a sample of the vomit for the doctor, who may need it for chemical analysis.

Activated charcoal can adsorb many chemicals and is another first aid treatment that can be administered when a pesticide has been swallowed.  Give the victim 2 to 4 tablespoons of activated charcoal in at least 8 ounces water and seek medical attention.

Only general first aid practices have been discussed here. Contact a poison control center for further assistance and get the victim to a doctor or hospital, remember to take the pesticide label with you. Some sources for pesticide poisoning emergencies are:

• National Pesticide Information Center: 1-800-858-7378
• Florida Poison Information Center: 1-800-222-1222

References:

• Fishel, F. 2010. Applying Pesticides Correctly.