CONTENTS 1.0 Introduction 2.0 Objectives 3.0 Main content
3.1 Sanitary Fundamentals of Pesticide Application 3.1.1 Sanitary classification of pesticides 3.1.2 Safe use of pesticides
3.1.3 Precautions 3.1.3.1The label
3.1.3.2Storage and transport 3.1.3.3Disposal
3.1.3.4General hygiene 3.1.3.5Protective clothing
3.1.3.5.1 Spraying indoors 3.1.3.5.2 Mixing
3.1.3.5.3 Impregnation of fabrics 3.1.3.5.4 Maintenance
3.1.3.6Safe techniques
3.1.3.6.1 Spraying
3.1.3.6.2 Impregnation of fabrics 3.1.4 Emergency measures
3.1.4.1Signs and symptoms of poisoning 3.1.4.2First-aid treatment
3.1.4.2.1 Vomiting
3.1.4.2.2 Caring for the patient 4.0 Conclusion
5.0 Summary
6.0 Tutor Marked Assignments 7.0 References and other Resources
1.0 INTRODUCTION
Pesticides are biologically active compounds that act not only on their targets, but also constitute a potential hazard for human health and the environment. All pesticides are poisonous, some more so than others.
Their toxic effects on target organisms are manifested not only during
the period of application, but also after application and may be chronic.
Some pesticides accumulate on objects of the environment, gradually concentrating in the food and fodder and becoming a real hazard to beneficial animals and humans. Extensive areas of agricultural lands and hundreds of thousands of tons of products are treated with pesticides, and hence they continue to circulate in human habitat. Pesticide residues are detected in the air, water, soil, plants and animals including human body. Consequently, use of pesticides must be regulated and monitored from a general sanitary viewpoint in terms of their fate and behaviour in the environment and the human body (Gruzdyev et al, 1983).
2.0 OBJECTIVES
By the end of this unit, students should be able to:
understand the safety rules for pesticide application;
understand the basis for sanitary classification of pesticides; and
understand the precautionary measures that should be taken by pesticide applicators during spraying and mixing of pesticides.
3.0 MAIN CONTENTS
3.1 Sanitary Fundamentals of Pesticide Application
Pesticides or their metabolites may poison humans and animals.
Pesticide poisoning may be occupational when it occurs among workers engaged in routine preparation of working formulations of pesticides or those spraying orchards or agricultural fields or those applying seed treatments. To prevent occupational hazard, it is necessary to comply strictly with the sanitary rules for applying, storing, and transporting pesticides. It is also necessary to observe the pre-harvest intervals after pesticide application and use the recommended personal protection equipment. The action of a pesticide on warm-blooded animals and animals depends on a multiplicity of factors, including the nature of its active ingredient, its dose, longevity of action, and the general well-being of the organism. Pesticides entering an organism spread rapidly in it, becoming selectively accumulated in separate parts or organs.
Proteins bind some pesticides, while others are metabolized and excreted from the organism.
3.1.1 Sanitary classification of pesticides
A sanitary classification allows for comparative characterization of various pesticides and determination of what pathological effect is of the greatest danger when applying a given pesticide. The relative toxicity of pesticides, and hence the danger they pose to warm-blooded animals, is expressed in a measure known as LD50, which stands for lethal dose, 50 percent. The LD50 is the amount of a pesticide that resulted in the death of 50 percent of a test animal population. It is based on milligrams (mg) of active ingredient per kilogram (kg) of body weight. Thus, the lower LD50, the more toxic a pesticide is to people as indicated in the table overleaf.
For simplicity’s sake, a pesticide label contains one of three “signal words” to indicate the product’s relative toxicity to humans:
DANGER applies to those pesticides with an LD50of less than 50 mg. These highly toxic pesticides require special certification to buy and use.
WARNING refers to pesticides that are only moderately toxic.
The LD50range for these pesticides is between 50 and 500.
CAUTION is applied to pesticides with low to very low human toxicity. The LD50 for this group is 500 or more. Most of the pesticides available to the homeowner contain the signal word CAUTION on their labels.
Interpreting toxicity categories and signal words on pesticide labels Toxicity
category
Oral LD50
(mg/kg)
Signal word Approximate adult lethal dose (oral)
I 0-50 DANGER/POISON Few drops to 1
teaspoon
II 50-500 WARNING 1 teaspoon to 1 ounce
III 500-5,000 CAUTION 1 ounce to 1 pint or
pound
IV 5,000 or
more
CAUTION More than 1 pint or pound
Regardless of the signal word on a pesticide label, remember that every pesticide is toxic and has the potential to poison. Therefore, always read the label and follow all of the directions on the label each time you use a
pesticide. It is always better to be safe than sorry. Read the product label, and be prepared to use the product in a responsible way. When children, pets or wildlife could be present, take special precautions (Kroening and Fishel, 2016).
3.1.2 Safe use of pesticides
Pesticides are toxic to both pests and humans, but they need not be hazardous to humans and non-target animal species if appropriate precautions are taken. Most pesticides will cause adverse effects if intentionally or accidentally ingested or if they are in contact with the skin for a long time. Pesticides particles may be inhaled with the air while they are being sprayed. An additional risk is the contamination of drinking-water, food or soil.
3.1.3 Precautions
Special precautions must be taken during transport, storage and handling of pesticides. Spray equipment should be regularly cleaned and maintained to prevent leaks. People working with pesticides should receive proper training in their safe use.
3.1.3.1 The label
Pesticides should be packed and labeled according to World Health Organization (WHO) specifications. The label should be in English and in the local language, and should indicate the contents, safety instructions (warnings) and possible measures in the event of swallowing or contamination. Always keep pesticides in their original containers; take safety measures and put on protective clothing as recommended.
3.1.3.2 Storage and transport
Pesticides should be stored in a place that can be locked and is not accessible to unauthorized people or children; they should never be kept in a place where they might be mistaken for food or drink as some beverages may have the same colour with some pesticides. Keep them dry but away from fires and out of direct sunlight. Do not carry them in a vehicle that is also used to transport food.
3.1.3.3 Disposal
Leftover insecticide suspension can be disposed of safely by pouring it into a specially dug hole in the ground or a pit latrine. It should not be disposed of where it may enter water used for drinking or washing, fishponds or rivers. Some insecticides, such as the pyrethroids, are very toxic to fish. Dig a hole at least 100 metres away from the streams, wells and houses. In a hilly area the hole should be on the lower side of such areas. Pour run-off water from hand washings into the hole, and bury containers, boxes and bottles used for pesticides in it. Close the hole as soon as possible. Cardboard, paper and cleaned plastic containers can be burned, where this is allowed, far away from houses and sources of drinking water. Pyrethroid suspensions can be poured on to dry ground where they are quickly absorbed and degraded and do not cause any environmental problems.
3.1.3.4 General hygiene
Do not eat, drink or smoke while using insecticide. Keep food in tightly closed boxes. Use suitable equipment for measuring out, mixing and transferring insecticides. Do not stir liquids or scoop pesticides with bare hands. Use the pressure-release valve of the pump or a soft probe to clear blockages in the nozzle. Wash the hands and face with soap and water each time the pump has been refilled. Eat and drink only after washing the hands and face. Take a shower or bath at the end of the day.
3.1.3.5 Protective clothing
Pesticides can enter the body in several ways: ingestion, inhalation or contact with the skin. Surveys indicate that most exposure victims contact pesticides through their skin. Consequently, personal protection equipment must be used when spraying and mixing pesticides, or during impregnation of fabrics with pesticides.