Recently Man became aware of the harmful effects of the ever-increasing number of synthetic insecticides and pesticides he has formulated, produced and exposed himself to. These hazardous chemical products initially intended for insects and pests now turned to be the silent (passive) killing agents of Man-himself and, Environmental disruptors (pollutants). These killing agents are called Persistent Organic Pollutants (POPs).
The greatest revolution of pest control formulation – the development of Synthetic Organic Pesticides was during the Second World War (World War 2) in the 20th Century. World War 2 was fought in the tropics, where insect vectored diseases like typhus, malaria, sleeping sickness to name a few, posed potentially devastating effects to human resources efforts of the war, affecting both sides. This prompted researchers to prioritized effective insecticides.
In the USA hundreds of chemicals from manufacturers were screened for insecticidal properties. One of those routinely tested materials –DDT was found to be what was been looked for by researchers. DDT was manufactured by a Swiss by the Gba Geigy Chemical Company of Switzerland, developed by a Swiss chemist, Paul Mueller. The DDT is a highly toxic substance (even in small quantities/doses) to virtually eliminate insects. On the other hand, the Western Allies came up with the Chlorinated Hydrocarbons, another equally toxic insecticidal compounds. The third group of synthetic organic insecticides the “cabamates” was also discovered by the Swiss in 1940s.
The following are some of the commonly known POP insecticides and pesticides:
1. Aldrin: a pesticide applied to soils to kill termites, corn rootworms, grasshoppers and other insect pests;
2. Chlordane: an insecticide extensively and intensively used in crop production as a broad spectrum insecticide;
3. DDT: widely used during World War 2 to protect soldiers and civilians from malaria, sleeping sickness and other diseases. In the recent past it was used in The Gambia to control malaria.
4. Dieldrin: this used to control termites, textile pests, vector control and soil borne insects;
5. Dioxin and Furans: they are unintentionally produced chemicals from incomplete combustion. They (furans) have also been found in exhaust of automobiles, smoke from wood, coal and tobacco;
6. Endrin: used in cotton and grains cultivation as spray and also rodenticide;
7. Heptachlor: used against termites, cotton and soil insects, grasshoppers, crops pests and mosquitoes to control malaria;
8. Mirex: used as fire retardants in plastics, rubber, electrical goods and also as insecticides against termites and ants;
9. Polychlorinated Biphenys (PCB): used as heat exchange fluids in electrical transformers and capacitors and as additives in paints and plastics;
10. Toxaphane: commonly known as camphechlor, used as abroad spectrum insecticide against ticks in livestock and mites;
11. Lindane: used as broad spectrum insecticide for seed and soil treatment. Also used for tree and wood treatment and, against ecto-parasites in veterinary and human applications;
12. Chlordane: a synthetic chlorinated organic mainly used as an agricultural pesticide;
13. Endosulphan: generally used as an insecticide in crops and against ecto-parasite in livestock. Highly toxic to human and environment and has been associated with deaths in farm workers in some parts of Africa and Asia.
However, the popular and wide use of the synthetic insecticides started in the late 1950s. Though the initial purpose was to control disease-carrying- and- infectious insects, after the war the agricultural enterprise became a good market for the synthetic insecticides and pesticides. The reasons being that they were cheap (cost effective), effective even in small quantities, easy to apply and are highly toxic.
By: Baboucarr Mbye
Stay Green Gambia (SGG)
(Reference: Dr. Roland Weber; Intergovernmental Forum on Chemical Safety (IFCS) and UNEP POPs Guide)