Using Agrichemicals Safely

In North Carolina, there is great diversity in the crops we grow, the lands we farm, the tillage practices we implement, and the range of agrichemicals we apply. Agrichemicals are chemicals used to improve the yields and quality of crops or animals with economic or aesthetic value. They control excessive pest damage or promote or regulate growth. Two of the most common agrichemical groups are defined in Table 1.

Table 1. Agrichemical Groups
 

The agrichemical industry is constantly expanding and changing: new products are being registered and introduced; new uses for previously registered products are being found; and uses for older products are being discontinued because of their adverse effect on the environment or human health. Advances in agrichemical technology have soared in the last few years. The proportion of chemicals to water for applications is continuously decreasing; the chemistry is becoming safer; and the packaging is now being designed to allow for little or no contact with the agrichemical by the user.

Farmers and homeowners have more choices of products to apply today than ever before for pest control, and there is an increase in the widespread use of agrichemicals. As a result, consumer awareness of the health and safety issues surrounding agrichemicals and their understanding of the effects that these materials can have on the body if they are carelessly used is more important than ever. Table 2 identifies the persons at risk of exposure to agrichemicals.

Table 2. Persons at Risk

Applicators and handlers who are knowingly in contact with chemicals occasionally or on a regular basis. For example:

• producers or manufacturers
• mixers
• loaders
• applicators
• farmers.

• field workers exposed to aerosols or residues on treated crops
• family members who experienee ehemieal contacts such as mixing contaminated work clothes with family laundry
• neighbors exposed to spray drift
• children who accidentally ingest pestieides being stored in or near the home
• consumers who might ingest agrichemicals in food or water or who might be accidentally exposed by improper storage

There are four main types of pesticides that control a variety of pests from weeds and fungi to insects and rodents. They are fumigants, fungicides, herbicides, and insecticides. The last of these groups includes nematicides. Following are some pointers about handling each of these and about handling fertilizers.

Fumigants are biologically reactive compounds that sterilize the soil so that any insect, disease, or weed pest that exists is either suppressed or eliminated. They are also used to treat stored or transported crops to prevent pest damage or spoilage. They are commonly used on seed beds that are being prepared for high-value agricultural crops or transplants. By observing the proper safety precautions and protective clothing guidelines when using these pesticides, the health risks involved are low.

Fumigants are gases and are known to be alkylating agents, mutagens, carcinogens, neurotoxins, or liver toxins. They can easily penetrate into the lungs and some may be rapidly distributed throughout the body. When working with fumigants, full respiratory protective equipment is mandatory. Death can occur quickly if fumes are inhaled even for a short period of time. Skin absorption of fumigants can also be harmful. Therefore, always take great care to adhere to label directions. Check your respiratory equipment before you use it to ensure that it is working properly, and change canisters and filters regularly to prevent exposure.

Fungicides control fungal diseases in crops and animals and are considered essential for many high-value crops such as fruits, vegetables, and ornamentals. Contact with some fungicides poses a risk for cancer. Some can cause birth defects in children whose mothers were exposed while pregnant, and some can cause allergic reactions and dermatitis especially among fungicide handlers. Most of these health concerns can be prevented by wearing protective clothing.

Herbicides kill weeds in agricultural crops. Groundwater contamination and spray drift are the two biggest concerns when working with herbicides. The herbicide group of pesticides contains many different chemical families.

One herbicide considered acutely toxic to people is paraquat. There is no known antidote if a tethal amount is absorbed into the body. However, most documented cases of paraquat poisoning were suicide attempts or a result of incorrect identification of the chemical. Today, most paraquat formulations contain an emetic (a substance that induces vomiting) and an additive that produces a recognizable stench and bitter taste to prevent children from swallowing it.

Many herbicides are being formulated to reduce direct contact by users. For example, some are being formulated into water soluble packaging, others into pellets, and others using lock-and-load systems.

Insecticides and Nematicides ki11 unwanted above ground and soilborne insects and nematodes. Many commonly used insecticides and nematicides belong to the organophosphate or n-methyl carbamate family of compounds. These compounds can be acutely toxic to both people and animals because they inhibit the enzyme acetylcholinesterase, which is necessary for nerve impulse transmissions. Unlike their organochlorine predecessors, most organophosphates and n-methyl carbamates degrade quickly and have low persistence

Fertilizers are the most widely used of all agrichemicals. Some type of fertilizer is applied to almost all land used to produce crops, including ornamentals and turf grasses. Fertilizers contain essential nutrients that improve crop yield. They can be formulated as dry powders, pellets, or liquids.

Because of the high salt content of fertilizers, they can burn the skin and irritate the eyes. Forms such as anhydrous ammonia can quickly burn the skin by freezing it and absorbing water from it and should never come into contact with any part of the body. Wear proper personal protective equipment when handling this chemical.

Some fertilizers are dangerous when they burn because they give off toxic gases or they are explosive. Therefore, fertilizer (and pesticide) storage areas need to be clearly identified to warn firefighters of the presence of these dangerous materials.

Hazard Recognition

Accidents happen because of carelessness, haste, lack of knowledge, or equipment breakdown. When working with agrichemicals, always protect yourself from exposure to the chemical by wearing the recommended personal protective equipment (PPE), such as chemical-resistant gloves, safety glasses or goggles, and coveralls.

Any of the following activities can unnecessarily expose you to harmful chemicals if you do not take the proper precautions to protect yourself:

• mixing, loading, or applying the chemical
• cleaning spills
• splashing onto the body
• calibrating or repairing equipment
• moving or transporting equipment and chemicals

Agrichemicals can enter the body through your mouth, skin, nose, or eyes (called dermal, oral, inhalation, and ocular exposure, respectively).

Oral Exposure (ingesting the chemical) can quickly provide a lethal dose. Some pesticides are so toxic that as little as a drop or taste can be lethal. Ingestion can occur by:

• not washing hands before eating, drinking, smoking, or chewing
• mistaking pesticides for food or drink
• accidentally applying a chemical to food, or eating crops that have recently been treated
• accidentally splashing pesticide into the mouth

Figure 1 shows the areas most sensitive to dermal. The two most common areas exposed to chemicals are hands and thighs. Your hands can be easily contaminated if you do not wear safety gloves or if you remove your gloves to work on equipment and do not wash your hands before putting the gloves on again. Your thighs can be exposed if you wipe your hands on your clothes instead of adequately washing them after they become contaminated. Common causes of dermal exposure are as follows:

• not washing hands after handling an agrichemical, agrichemical container, or equipment
• splashing or spraying chemicals on unprotected skin
• not removing or improperly washing pesticide-contaminated clothing
• applying pesticides in windy weather
• not wearing adequate personal protective equipment (PPE)
• reentering treated areas too soon without protection
• touching contaminated surfaces (for example, equipment, tools, or clothing)

Inhalation Exposure (breathing in the pesticide) from spray drifts, dust, vapors, or particles can damage the respiratory tract. When working closely with a pesticide, always wear the respiratory protection suggested on the package label. Make sure its cartridges or canisters are fully functional and are replaced after 8 hours of use or anytime you can smell or taste the chemical. Examples of situations when inhalation exposure can occur are

• working in poorly ventilated or enclosed areas for prolonged periods of time
• breathing in vapors from fumigants or other toxic pesticides
• not wearing the proper PPE suggested on the pesticide label
• inhaling vapors of recently applied pesticides (for example, inhaling spray drift or reentering the area too soon)
• using an inadequate respirator (for example, one that fits poorly or that has old or worn-out parts such as the filter, cartridge, or canister)

splashing or spraying pesticides into the eyes
applying an agrichemical in windy weather without eye protection
rubbing the eyes or head with contaminated hands or gloves O pouring dust, granular, or powder formulations without eye protection.

Toxicity

Toxicity is a measure of the ability of a pesticide to harm the body and can be acute or chronic. When working with pesticides, be aware of any unusual reactions you have to a particular pesticide or group of related pesticides. When choosing a pesticide for a particular job, check the toxicity of each product and consider using the least toxic. With pesticides, toxicity depends on several factors. Some pesticides are highly toxic, while others are relatively nontoxic depending on the type of formulation (dust, granular, powder, or emulsifiable concentrate) and the type and amount of:

• active ingredients
• carrier or solvent ingredients
• inert ingredients

Table 3. Categories of Acute Toxicity
 

Acute Toxicity

Acute toxicity is the adverse effect that results from a single exposure to a toxic material. Acute toxicities usually appear immediately after exposure to a pesticide or within 24 hours. The symptoms of acute chemical exposure (or poisoning) are common to many illnesses or other health problems; therefore, sometimes it is difficult to link them to pesticide exposure. Table 4 lists some of the most common symptoms .

Table 4. Common Symptoms of Acute Toxicity
 

Acute oral effects. Some pesticides burn or irritate the mouth or digestive tract or are absorbed through the lungs into the body where they cause other problems.

Acute inhalation effects. Some pesticides burn the delicate lining of the nose, mouth, trachea, and lungs, making it difficult to breathe or causing permanent tissue damage. Others can be absorbed into the body and cause other problems.

Acute ocular effects. Because of the sensitivity of eye tissues to damage, exposure to some agrichemicals can cause temporary or permanent blindness, or mild to severe irritation.

Acute dermal effects. Itching, blistering, drying, cracking, a change of skin color, or allergic reactions are considered acute dermal effects. Even though many pesticides do not affect the skin directly (they are absorbed through the skin and damage the body in other ways), the most common occupational disease among farm workers is dermatitis (skin irritation). Dermatitis can be caused by agrichemicals or by crops or weeds. There are three types of dermatitis to watch for.

1. Primary irritant dermatitis is a non-allergic, inflammatory response that occurs when a material, such as a pesticide, comes in contact with the skin.

2. Allergic contact dermatitis occurs when an allergenic substance contacts previously sensitized skin. An allergen is any agent capable of causing an allergic response. You may be exposed to an allergen for many years before becoming sensitized. Once you are sensitized to an agent, you can have an allergic response with every subsequent exposure to the agent. The most effective way to prevent allergic contact dermatitis is to prevent dermal expo- sure to chemicals and plant materials whenever possible.

3. Photosensitivity dermatitis occurs between 2 and 12 hours after exposure to sunlight. It appears as a sunburn-type reaction and may include swelling and blisters.

Chronic Toxicity

Chronic toxicity is usually caused by repeated exposure over a prolonged period of time to a relatively small amount of a toxic material. Chronic effects of toxicity usually do not appear right away and can lead to permanent health problems. Because they are normally vague and gradual, it is often difficult to recognize the signs of chronic pesticide poisoning. Usually by the time they are recognizable, the symptoms have progressed into a chronic illness, such as cancer or emphysema. The early warning signs of chronic chemical exposure are listed in Table 5.

Table 5. Common Symptoms of Chronic Toxicity
 

The pesticide label section "Hazards to Humans and Domestic Animals" should state whether delayed effects (such as cancer or birth defects) have occurred in lab animals. These warnings are placed on pesticide labels in order to urge people using these products to be exceptionally careful. The chronic effects of agrichemicals include

Carcinogenic effects that cause the production of a malignancy (cancer).

Mutagenic effects that cause changes in genes or chromosomes that may lead to cancer.

Developmental effects that affect the fetus while in the womb of a woman who has been exposed to a pesticide and reproductive effects that affect the reproductive system or a reproductive organ or function. For example,

teratogenic effects (birth defects)
fetotoxic effects (miscarriage or stillbirth)
infertility (low sperm count), sterility, or impotence
 

Delayed systemic effects that injure a body system and do not become noticeable until 24 hours or longer. (These effects can be permanent or recovery can be slow or incomplete.) For example,

hemotoxic effects (blood disorders) such as anemia or inability to coagulate
neurotoxic effects (nerve or brain disorders) ranging from muscle weaknesses to paralysis, nervousness, anxiety, irritability, shortened attention span, memory loss, behavioral changes, tremors, blindness, or brain damage
lung and respiratory disorders such as asthma and emphysema
liver and kidney disorders such as jaundice and kidney failure

Safety Labels

Every product on the market is required by law to have a label that contains all the information needed or required to use the product safely and effectively and to dispose of it. The Environmental Protection Agency (EPA) has tough standards that pesticides and their labels must meet. Never use a pesticide without reading the label first! The health and human safety sections that appear on the label are listed below.

Restricted-Use Designation. These products, because of their high toxicity to people or animals or their potentially harmful environmental impact, can be sold to and used by only a certified applicator or someone under his or her direct supervision. If this provision is not adhered to, serious harm could be done to the persons injured and legal action could follow.

Signal Words and Symbols. The signal words indicate how acutely toxic the pesticide is to people and appear directly below the statement "Keep out of reach of children" on every label. The signal words and symbols for highly toxic substances include the words DANGER—POISON, or an illustration of a skull and crossbones, or the word DANGER. Highly toxic substances are likely to cause severe oral, dermal, or inhalation poisoning; some may cause skin and eye irritation.

Statement of Practical Treatment. This statement gives the first aid information in case of an emergency, for example, whether or not the person exposed to the chemical should be seen by a physician immediately and whether or not vomiting should be induced. If this statement does not appear in full on the front panel of the label, there will be directions on the front panel that tell you where to find it. Often the manufacturer's emergency phone number appears here as well.

Following are some common statements that indicate hazards to people or to domestic animals:

Acute effects statements tell the route of entry (oral, dermal, inhalation, or ocular) from which you must be careful to protect yourself. For example, "DANGER: Fatal if absorbed through the skin and fatal if swallowed. Do not get on skin or clothing."
Delayed effects statements tell you if the product has been found to cause delayed effects such as tumors, nerve damage, or reproductive problems in people or laboratory animals.
Allergic effects statements tell you if the product could cause allergic reactions such as skin irritations or asthma.
Personal protective equipment (PPE) statements identify the minimum requirement of PPE to be worn when using the product. Be careful to use only NlOSH-approved equipment (especially respirators) when it says so on the statement. Read the information carefully. The statement should tell you if you need a certain type of chemical- resistant gloves (for example, butyl or nitrile), protective eyewear, hat or hood, or any other special require- ments. Wearing the appropriate or recommended PPE is essential for your health and safety.

Figure 2 shows examples of PPE. Not pictured in Figure 2 are ear plugs, which are often highly recommended because of the sensitivity of the ear canal to dermal absorption.

Physical or chemical hazard statements tell you if the product presents danger of fire, explosion, or chemical hazards from inappropriate storage or contacts.

Entry statements identify the length of time that must pass before it is safe to enter an area where the product has been applied. You must inform anyone that has the potential to go in or near a treated area (for example, neighbors or road crews) by posting reentry signs and by word-of-mouth. The Worker Protection Standard of 1994 requires that all hired agricultural workers and handlers in farm, forest, nursery, and greenhouse situations are trained to properly handle the agrichemicals they use on the job.

Summary

The agrichemical industry is expanding rapidly, and continually offers both private and commercial consumers more types of chemicals that they can apply to control pests or fertilize their gardens and crops. The industry is also developing safe packaging to lower the risk of exposure to the chemical.

However, CONSUMERS BEWARE! Agrichemicals are still hazardous and sometimes even lethal if the proper handling precautions are not strictly observed. Following the label instructions carefully and checking your Personal Protective Equipment to ensure that it is in good repair is your best protection against harmful exposure.

References & Additional Information

Environmental Protection Agency, Extension Service: Applying Pesticides Correctly: A Guidefor Private and Commercial Applicators, United States Department of Agriculture, Washington, District of Columbia, 1991.

Hughes, H.: Fundamentals of Machine Operation: Crop Chemicals, Deere and Company, Moline, Illinois, 1982.

Lyons. M.: Health Provider Guide to Evaluation of Pesticide Exposure of Farm Workers, New Jersey Department of Health and Rutgers University Labor Education Center, April 1990.

Morgan, D. P.: Recognition and Management of Pesticide Poisonings, Environmental Protection Agency, 1989.

Moses, M.: Pesticide-Related Health Problems and Farmworkers, AAOHN Journal, Vol. 37, No. 3, March 1989.

North Carolina State University, College of Agricultural and Life Sciences: 1994 Agricultural Chemicals Manual, Raleigh, North Carolina, 1994.

United States Environmental Protection Agency and Extension Service, United States Department of Agriculture: Applying Pesticides Correctly: A Guidefor Private and Commercial Applicators, Washington, DC, 1991.

United States Environmental Protection Agency: The Worker Protection Standards for Agricultural Pesticides: How to Comply, 1992.

For more information contact:
Grant Ellington-Extension Associate
NC State University
Biological & Agricultural Engineering
Campus  Box 7625
Raleigh, North Carolina 27695-7625
PHONE: (919) 515-6793
FAX: (919) 515-6772
e-mail: Grant Ellington  ghelling@eos.ncsu.edu