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Information on Deltamethrin
Pyrethroids are synthetic chemical insecticides that act in a similar manner to pyrethrins, which are derived from chrysanthemum flowers. Pyrethroids are widely used for controlling various insects.Deltamethrin is a synthetic pyrethroid commonly used in mosquito control programs to kill adult mosquitoes.
Though pyrethoids are a "friendly insecticide", they are still toxic, and people may question why they are used. The simple answer is that they save lives, millions of them. Using a treated net over a small child can reduce the child´s chance of dying by 25%. Malaria is one of the leading causes of children´s deaths in much of the world.
Synthetic pyrethroids are the only group of chemicals recommended for use on mosquito nets. Deltamethrin is perhaps the best known insecticide of this group, and it has been used to treat nets for many years.
All insecticides marketed for net treatment are reviewed by the WHO Pesticide Evaluation Scheme (WHOPES). They are all assessed for safety, efficacy, ease of application, acceptance and cost effectiveness.
Though synthetic pyrethroids are safer than most other commonly used insecticides they can still be harmful to people, beneficial insects, fish and the environment. The risk of adverse effects depends on the type of insecticide, the formulation, the concentration and the degree and mode of exposure.
See the sidebar for tips on good practice.
The user
Some people experience minor side effects such as a runny nose when they sleep under a freshly treated net (first 2 to 3 days), and EC formulations (Emulsifiable Concentrate) can be more irritant than other formulations. After the first week the chemical is usually undetectable, although some asthmatics can detect it when other people cannot.
Treated nets are recommended for use by people of all ages including babies, in areas where malaria is a serious risk. There is no evidence of long term toxicity in humans, however there are ongoing toxicological studies to specifically look for long term side effects.
Hundreds of thousands of nets are treated and used in Africa every year and many millions in China, Vietnam and the rest of Asia and the Pacific.
The environment
Unlike DDT, pyrethroids do not persist in the environment for long periods of time.
Though they stay on nets for several months, in soil they break down into less toxic
products, with a half-
They are however extremely toxic to fish and other fresh water animal life. They may also harm silk moth and honeybees. So it is very important that the insecticide is used properly, and that any waste is disposed of correctly (in pit latrines and garbage pits; not in watercourses).
Insecticide treated nets should not be washed in rivers, streams or ponds.
Good practice
1. Nets usually requiretreatment once or twice a year (depending on the insecticide used and washing practices).
2. Nets should only be treated with recommended formulations of the chemicals (NB synthetic pyrethroids are frequently used in agriculture, however they are prepared using different solvents, which are not recommended for public health use).
3. Each insecticide has adosage range recommended for net treatment, this should not be exceeded.
4. Wearing gloves is recommended when treating nets. Omitting them may cause tingling of the hands and if the solution is inadvertently wiped in the mouth or eyes it will cause stinging.
Related resources
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