Insecticides

An insecticide is a substance used by humans to gain some advantage in the struggle with various insects that are considered "pests." In the sense used here, a pest insect is considered undesirable, from the human perspective, because: (a) it is a vector that transmits diseasecausing pathogens to humans (such as those causing malaria or yellow fever), or other diseases to livestock or crop plants; or (b) it causes a loss of the productivity or economic value of crop plants, domestic animals, or stored foodstuffs. The abundance and effects of almost all insect pests can be managed through the judicious use of insecticides.

However, the benefits of insecticide use are partly offset by important damages that may result. There are numerous cases of people being poisoned by accidental exposures to toxic insecticides. More commonly, ecological damage may be caused by the use of insecticides, sometimes resulting in the deaths of large numbers of wildlife.

Humans have been using insecticides for thousands of years. The Egyptians used unspecified chemicals to combat fleas in their homes about 3,500 years ago, and arsenic has been used as an insecticide in China for at least 2,900 years. Today of course, insecticide use is much more prevalent. During the 1990s, more than 300 insecticides were available, in hundreds of different formulations and commercial products (which may involve similar formulations manufactured by different companies).

Almost all insecticides are chemicals. Some are natural biochemicals extracted from plants, while others are inorganic chemicals based on toxic metals or compounds of arsenic. However, most modern insecticides are organic chemicals that have been synthesized by chemists. The costs of developing a new insecticide and testing it for its usefulness, toxicology, and environmental effects are huge, equivalent to at least $20-30 million. However, if an insecticide effective against an important pest is discovered, the profits are also potentially huge.