Pesticides have numerous beneficial effects. These include crop protection, preservation of food and materials and prevention of vector-borne diseases.

For example pesticides may be used in the prevention of malaria, which kills up to 1 million children per year, and for preventing other vector-borne diseases such as dengue, leishmaniasis and Japanese encephalitis.

Pesticides are toxic by design – they are BIOCIDES, designed to kill, reduce or repel insects, weeds, rodents, fungi or other organisms that can threaten public health and the economy.

Their mode of action is by targeting systems or enzymes in the pests which may be identical or very similar to systems or enzymes in human beings and therefore, they pose risks to human health and the environment.

Pesticides are ubiquitous in the environment and most are synthetic.

There is growing concern about children's exposure to pesticides and their special susceptibility. Children are not little adults, and may have higher exposures and greater vulnerability at both high and low levels of exposure.

a)  First use of synthetic pesticides: 1940


b)  Consumption increased substantially over time, for example, in the USA, the use of pesticides doubled from 1960 to 1980, but total use has since remained stable or fallen. Most pesticides are used in agriculture, but in 1999 about 74% of households in USA were reported to use at least one pesticide in the home.


c)  Use has risen in developing countries and the fastest growing markets in Africa, Asia, South and Central America, Eastern Mediterranean. There is a high pesticide use on crops grown for export (Dr. N. Besbelli, WHO, personal communication).




What are agricultural pests?

There are different pests that destroy crops in agriculture such as: 
• Weeds or unwanted plants 
• Insects 
• Rodents 
• Fungi



Types of pesticide

Many different types of pesticides are used on farms. They are grouped (classified) according to their use” or pests they intend to kill. The following are the most common types used 
• Herbicides - are meant to kill weeds 
• Insecticides - are meant to kill insects 
• Fungicides- are meant to kill fungi 
• Rodenticides- are meant to kill rats, mice and other pest species of rodents. 

 These different pesticides are applied in agricultural activities such as weed killing, crop protection, stock protection, soil fumigation, stock disinfection, etc.



Effects of pesticides

Use, overuse and misuse of pesticides have effects on humans and the environment. Their effects on humans are either acute or chronic effects causing some of the following: 
• Damage to the nerves 
• Damage to the lungs 
• Cancer 
• Sterility
• Birth defects 
• Allergic reactions 
• Fatal poisoning. In short, they cause injuries, ill health, death and environmental degradation.
 It therefore becomes necessary to understand how pesticides enter the human body.