The use of chemical pesticides has become widespread due to its relatively low cost, its ease of application and its effectiveness, availability and stability. Chemical pesticides are generally fast acting, which limits crop damage.

Chemical pesticides have some important disadvantages, however, they are still widely sold and used. In this article, here we will discuss four of the disadvantages of chemical pesticides. First of all, chemical pesticides are often not only toxic to the organisms for which they were conceived, but also to other organisms. Chemical pesticides can be subdivided into two groups: non-selective pesticides and selective pesticides. Non-selective pesticides are the most dangerous, because they kill all kinds of organisms, including harmless and useful species.

For example, there are herbicides that kill both broadleaf weeds and grasses. This means that they are not selective, since they destroy almost all the vegetation. Selective pesticides have a more restricted scope. They only destroy the plague, the disease or the weed, without affecting other organisms. As an example we can name a herbicide that acts only on broadleaf weeds, so it can be used on the lawn already, which does not kill the grass. Nowadays, usually, a combination of several products is required for the control of several pests, since almost all the allowed products are selective and, therefore, only control a certain range of pests.

Another disadvantage of chemical pesticides is resistance. Pesticides are usually effective only for a (short) period of time for a particular organism. Organisms can develop immunity to a certain substance, losing its effect. These organisms mutate and become resistant, which results in the need to use other pesticides for their control.

A third drawback is the accumulation. If the sprayed plants are attacked by an organism, and that organism is eaten by another, the chemicals can enter the food chain. Animals that are at the top of the food chain, usually predators or humans, are at increased risk of poisoning due to the accumulation of pesticides in their system. This effect, however, is becoming less relevant because pesticides are forced to degrade more rapidly so that they can not accumulate. Otherwise, its sale is prohibited.