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 etal, 1983).
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.
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.
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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 LD50 of 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 LD50 range 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
|Few drops to 1 teaspoon
|1 teaspoon to 1 ounce
|1 ounce to 1 pint or pound
|5,000 or more
|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).