What is Pesticides and Effect on human health

Definition of pesticides

Agriculture, forestry, aquaculture, food industry, processing, transportation and storage of wood and other biological products are sectors where various pests (e.g. weeds, insects, birds, rodents, fungi, moulds, etc.) can significantly affect the quantity and quality of products. Certain species of pests can also damage buildings, installations, furniture, cloths, etc., spread infectious or cause other diseases. Therefore pest control is an important activity intended to reduce or eliminate yield losses, maintain high quality of products and prevent other undesirable effects that may be caused by pests.

Pest control is implemented by physical, chemical and biological methods and the choice of the particular method depends on various conditions (type of industry, species, amount and distribution of pests, environmental conditions, etc.). The most effective methods of pest control are based on the use of chemicals named ‘pesticides’. The largest users of pesticides are agriculture and forestry. Pesticides are also widely used in different industries, trade, storage and other sectors of economic activity and household. Adequate application of pesticides produces good results in terms of protecting products and improving quality, saving labour costs and achieving a significant economic benefit. 

The Food and Agriculture Organisation of the United Nations (FAO) presents following definition of pesticides:

‘Pesticide means any substance, or mixture of substances of chemical or bio- logical ingredients intended for repelling, destroying or controlling any pest, or regulating plant growth’.

Pesticide is a more general term than Plant Protection Product (PPP). Plant protection products are 'pesticides' that protect crops or desirable or useful plants. They contain at least one active substance and have one of the following functions:

• protect plants or plant products against pests/diseases, before or after harvest;
• influence the life processes of plants (such as substances influencing their growth, excluding nutrients;
• preserve plant products;
• destroy or prevent growth of undesired plants or parts of plants.

The term 'pesticide' is often used interchangeably with 'plant protection product', however, pesticide is a broader term that also covers non plant/crop uses, for example biocides.

Examples of pesticides

1. Examples of pesticides are fungicides, herbicides, and insecticides. Examples of specific synthetic chemical pesticides are glyphosate, Acephate, Deet, Propoxur, Metaldehyde, Boric Acid, Diazinon, Dursban, DDT, Malathion, etc.

Types of Pesticides

These are grouped according to the types of pests which they kill:

Grouped by Types of Pests They Kill

1. Insecticides – insects
2. Herbicides – plants
3. Rodenticides – rodents (rats & mice)
4. Bactericides – bacteria
5. Fungicides – fungi
6. Larvicides – larvae

Benefits of Pesticides

1. The major advantage of pesticides is that they can save farmers. By protecting crops from insects and other pests. However, below are some other primary benefits of it.
   • Controlling pests and plant disease vectors.
   • Controlling human/livestock disease vectors and nuisance organisms.
   • Controlling organisms that harm other human activities and structures.

Impacts on Human Health

An estimated 2.2 million people are at risk due to exposure from agricultural pesticides, with the majority of this population being locating in developing nations.

Pesticides can enter the human body through inhalation, ingestion, or by dermal penetration through the skin. Those who work with agricultural pesticides are the most at risk if they are not properly dressed or if there are broken and leaking equipment. The majority of average citizens who are effected by the pesticides intake the pesticide through consumption of a food that was been contaminated with a pesticide."In 1958, all members of the family of a local chief who is a prominent cocoa farmer at Okebode in southwestern Nigeria were hospitalized after eating a leaf vegetable undergrowth of a cocoa farm that was earlier sprayed by lindane. In 2004, carbofuran pesticide residues found on several batches of noodles manufactured in Nigeria may have resulted in 23 reported cases of vomiting and one death" (Monosson, 1).

Pesticides cause headaches, blurred vision, vomiting, abdominal pain, suppress the immune system, lead to blood and liver diseases, depression, asthma, and nerve damage. The issue with these effects is that they may wait appear until a while after being ingested so tracing the symptoms back to the pesticide can prove to be quite difficult. Many of the symptoms can be mistaken for the flu and therefore not properly treated. The inactive ingredients such as chloroform can also cause serious risks to the liver and nervous system. These effects can also be experienced by the animals living around the streams where the pesticides accumulate. The pesticides bioaccumulate within the animals as they are not easily soluble, as that animal is eaten by another animal the pesticide then biomagnifies and obtains an even higher concentration as it moves further up the food chain.