The concept of pesticide It covers any chemical substance or compound used to control or eliminate pests that affect agricultural crops or public health. Pesticides can be presented in different forms, such as liquid, solid or gaseous, and have various classifications based on their mechanism of action, such as insecticides, herbicides, fungicides, acaricides, bactericides, rodenticides and phytohormones.
However, although their use has been fundamental, especially after the Green Revolution, the environmental effects of pesticides have raised serious concerns regarding their impact on water, soil and living organisms that depend on these resources. This article will seek to explain in depth the effects of pesticides on the environment and human health, as well as their main characteristics.
Use of pesticides in agriculture
The Green Revolution, pesticides have played a crucial role in agricultural production, allowing a considerable increase in the quantity and quality of food produced worldwide. To combat diseases and pests, chemical substances began to be used massively, transforming agriculture and giving rise to the so-called 'chemical era' in the 1950s.
Pesticides are commonly used to combat insects, diseases and weeds that threaten production. However, along with the benefits, serious side effects have been observed. These include: biodiversity decline, alterations in the relationships between predators and prey, and adverse effects on human health through prolonged or inappropriate exposure to these products.
Environmental effects of pesticides
The main problem lies in the spread and dispersion of pesticides in the environment. Through direct application on crops, accidental spills, residues from containers and inadequate storage, pesticides can contaminate elements Biotics (such as animals and plants) and abiotic (such as air, soil and water). This endangers public health and local wildlife.
The effects of pesticides on the environment vary depending on the composition of the pesticide and the environmental conditions. This includes physicochemical properties and climatic factors, which interact to determine the degree of impact. However, two processes are key to understanding the damage they can cause: bioconcentration y bioamplification.
Bioconcentration
Bioconcentration is the process by which chemicals, such as pesticides, move from the external environment into the interior of living organisms. Some pesticides, such as DDT, are lipophilic, meaning they accumulate in the fatty tissues of living organisms, including humans. This accumulation can have serious long-term effects, such as the buildup of toxins in edible tissues of animals or even inside the human body.
Bioamplification
Another important phenomenon is biomagnification, which describes the increase in pesticide concentrations within the food chain. As predators consume their prey, the concentration of these chemicals is amplified. The result is that predators, including humans, accumulate higher levels of pesticides, which can lead to long-term damage such as immune disorders, cellular deterioration, or malignant tumors.
Pesticide contamination and persistence
The ability of pesticides to persist in the environment depends on several characteristics. Some pesticides can be rapidly broken down by exposure to sunlight or through biological processes such as hydrolysis. However, many pesticides have a long half-life, meaning they can persist in the environment for months or even years, putting future generations at risk.
Toxicity and LD50
The toxicity of a pesticide is commonly measured by its toxicity value. LD50, or lethal dose. A pesticide with a low LD50 is extremely toxic, as only a small amount is needed to cause death in 50% of exposed individuals. For example, DDT, a pesticide commonly used in the 1950s, has extremely high toxicity and has been linked to the deaths of birds of prey due to the thinning of their eggshells.
The toxic effects of pesticides may not appear immediately, as some chemicals affect the circulatory system or cause neurological disorders after chronic exposure.
Effects on human health
Exposure to pesticides affects both workers who handle them directly and people who are indirectly exposed through air, water or consumption of contaminated food. Acute effects include nausea, headaches and respiratory problems. However, chronic effects can be more insidious, causing cancer, neurological damage and reproductive disorders.
Children, pregnant women and people with compromised immune systems are especially vulnerable to the harmful effects of pesticides.
Prevention and mitigation
To protect both human health and the environment, it is crucial to implement alternative techniques to the use of pesticides in agriculture. Alternative techniques to pesticides ecological agriculture and integrated pest management, which seek to reduce the use of these products through crop rotation, the use of natural enemies of pests and the appropriate selection of biodegradable pesticides, are important options that must be implemented globally.