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Deet (Molecule of the Month for September 2002)

Insect Repellents



Ever wondered what's in bug spray and what drives those annoying bugs away? Well you're about to find out! The most common insecticide used in bug spray which is used on skin is a chemical called DEET also known as N,N-diethyl-m-toluamide. Another substance called Permethrin is often used on clothing, tents etc. There are also several natural insecticides like citronella, oils of cedarwood, lemongrass, peppermint, eucalyptus,soya bean oil, garlic and many more.

Blood sucking insects are attracted to many chemical and physical factors, including carbon dioxide, body heat, chemicals in sweat, and on the surface of skin, and odor of soaps and lotions we use.

Insect bites can be annoying for the itching they cause but they can also be harmful by transmitting certain diseases to humans. Malaria is the most commonly known disease caused by female mosquitos passing on the malaria virus into the blood stream of humans. It is estimated to cause approximately 3,000,000 deaths every year worldwide.

Insect bites can also cause allergic reactions in people which can, in rare cases be fatal.

Lyme disease is also one of the better known insect spread diseases. It is carried by ticks, most commonly known the deer tick. It is highly treatable in the early stages but if left undetected it can cause serious long term disabilities such as joints, severe headaches, and abnormal heart beat.

Ticks can also transmit Rocky mountain spotted fever, Colorado tick fever, and several forms of encephalitis.

DEET is an insect repellent on humans. It is an especially affective repellent on mosquitos. It is also a repellent for biting flies, gnats, chiggers, ticks, fleas, and certain other biting insects. It was discovered and developed by scientists at the U.S. Department of Agriculture and was patented by the U.S. Army in 1946. Later in 1957 it was registered for use by the generel public in 1957. Twenty years of research into insecticides has not resulted in an insecticide that works as well or on as many insects as DEET.

DEET works to repel biting insects, by blocking the receptors on an insect's antennae which help it home in on its host.

Recently there have been increasing debates as to whether DEET is a safe substance to use on human skin. DEET has has extensive independant research into its safety for several years and has proved safe to use as long as safety instructions are followed. The most common complaints are eye and skin irritation. Deet is not for use on the eyes and should be applied carefully on to the face by first spraying it on to your hands and then carefully rubbing on to your face. DEET can be a skim irritant but does not create a skin sensitivity.

Formal Chemical Name (IUPAC)
3-methyl-N,N-diethylbenzamide

Picture of Deet

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Deet structure
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Picture of Deet

C12 H17 N O



Update by Karl Harrison
(Molecule of the Month for September 2002 )