What are pesticides and how do they work?
Pesticides utilized in agriculture are synthetic or natural substances used to combat dangerous or unwanted organisms, and are used for crop protection.
Pesticides can have an extremely beneficial effect on increasing food production, by reducing the losses in agriculture. However, the negative effects accumulate, ultimately outweighing the positive ones many times over. Since they are poisons, pesticides can be highly dangerous for the human body as well as other living beings.
They became popular after WWII and started being used in order to increase food production (which was crucial considering the post-war destruction) and to help avoid famine. Currently, 3.2 million tons of pesticides are used worldwide per year.
Farmers’ lack of knowledge on the guidelines on using pesticides and reducing their harmful effects on the environment translates to an increase in environmental pollution. Without adequate regulations, pesticide may spread far from their usage site. This phenomenon is especially common in developing countries, where improper usage of pesticides results in e.g. contamination of surface- and groundwater.
It is basically impossible for pesticides to only affect the area they have been applied to.
Pesticides spread by:
- Wind: raises them from the ground and transports them to e.g. other fields or rivers.
- Soil: they contaminate the soil and enter e.g. ground-living organisms or groundwater.
- Plants: absorbed by other plant species than intended, they have a negative effect on their growth.
- Water: they remain on the ground and contaminate surface waters during rain, or flow into rivers and streams. Once dissolved in ground or surface waters, pesticides enter the bodies of plants and animals. The accumulation of pesticides in bodies of water may reach quite high levels.
While there are regulations regarding limits of residue for plants and animals, they rarely take into account that living organisms ingest or absorb water, contain high amounts or pesticide residue or their compounds. This also influences people who eat fish, as fish absorb harmful chemicals in their flesh. Of course, the most direct way of consuming pesticides for humans is by drinking from the contaminated water sources directly.
Effect on human health
It is estimated that 2.2 million people are at a direct risk associated with agricultural usage of pesticides, with most of these people living in developing countries.
Pesticides enter the human body through:
- consumption (e.g. contaminated meat or plants)
The group most at-risk is farmers, especially if they do not use protective clothing, or use damaged or leaking spraying equipment. Remaining people have achieved pesticide accumulation in the body by consuming contaminated food.
Pesticides exposure symptoms
- blurry vision
- vomiting and stomach aches
- decreased immune efficiency
- blood and liver diseases
- nerve damage
Negative effects may not occur immediately after exposure, but some time after consumption or contact. Many of the above-mentioned symptoms can be confused with flu, causing pesticide poisoning to be treated incorrectly.
Since they are not easily soluble, pesticides accumulate inside living organisms, pass from one organism to the next. When e.g. one animal eats another, it gradually achieves higher concentration, the higher it is in the food chain.
Prevention or mitigation
The simplest way of preventing agricultural pesticide runoff is education. If more farmers, especially in developing countries, knew the associated risks, they would be more careful when using pesticides. Another, more sophisticated, way is through integrated regulation regarding the usage of pesticides in agriculture and the available substitutes, such as removing the diseased parts of plants, crop rotation which can interfere in pests’ lifecycle, and biological control using insect-eating animals.