The best known organochlorine insecticide is DDT, noted for its broad spectrum of activity, its persistence and its accumulation in the body fat of mammals. DDT shares these properties with the other organochlorines, examples of which are aldrin, dieldrin, endosulfan and gamma-HCH or gamma-BHC. The organochlorines can be divided into subgroups according to structural differences but they have in common chemical activity that affects synaptic transmission, their stability, low solubility in water, moderate solubility in organic solvents and a low vapour pressure (Hill and Waller, 1982). The stability and solubility of the organochlorines means that they are highly persistent and this may lead to long term contamination of the environment and gradual accumulation in animals at the higher end of the food chain. If organochlorines present in the body fat reach a high level, when the fat is broken down during periods of food shortage sufficient chemical can be released into the blood to cause poisoning and even death. For these reasons organochlorine insecticides have been banned by most developed countries, although they are still produced, sold and used in many developing countries where they are usually one of the cheapest insecticides available. The broad spectrum activity of organochlorines, their persistence and hazard to the environment mean that their use in insect pest management is largely considered inappropriate, although as a chemical group there still remain situations where they are an important control option, e.g. mosquito control.

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