DEET

'N,N-diethyl-''m''-toluamide', abbreviated 'DEET', is an insect repellent chemical. It is intended to be applied to the skin or to clothing, and is primarily used to protect against insect bites. In particular, DEET protects against tick bites (which transmit Lyme disease) and mosquito bites (which transmit dengue fever, West Nile virus, Eastern Equine Encephalitis (EEE), and malaria).
DEET is believed to work by blocking insect receptors (notably those which detect carbon dioxide and lactic acid) which are used to locate hosts. DEET effectively "blinds" the insect's senses so the biting/feeding instinct is not triggered by humans or animals which produce these chemicals.

Contents

History

Chemistry

Concentrations

Effects on health

Effects on materials

Effects on the environment

Natural alternatives

References

See also

External links

History

DEET was developed by the United States Army, following its experience of jungle warfare during World War II. It entered military use in 1946 and civilian use in 1957.

Chemistry

A slightly yellow liquid at room temperature, it can be prepared from m-methylbenzoic acid and diethylamine. This can be achieved by preparing the acid chloride and subsequently reacting that with the diethylamine. It can be distilled under vacuum: b.p. 111 ^oC at 1 mm Hg.
It is considered a mild irritant.

Concentrations

DEET is often sold and used in concentrations up to 100%. ''Consumer Reports'' found a direct correlation between DEET concentration and hours of protection against insect bites. 100% DEET was found to offer up to 12 hours of protection while several lower concentration DEET formulations (20%-34%) offered 3-6 hours of protection. Essential oil analysis and field evaluation of the citrosa plant "Pelargonium citrosum" as a repellent against populations of Aedes mosquitoes., Matsuda, Brent M.; Surgeoner, Gordon A.; Heal, James D.; Tucker, Arthur O.; Maciarello, Michael J., , , Journal of the American Mosquito Control Association, 1996 Other research has corroborated the effectiveness of DEET.^[1]

Effects on health

DEET is the most common active ingredient in insect repellents. Studies into the health effects of using DEET in the approved way (as a topical application) have not shown any significant harm to human health; exposure to large amounts (by means such as accidental ingestion) has similar effects to comparable exposure to other pesticides. As a precaution, manufacturers of DEET based products advise they should not be used under clothing, on damaged skin, and that the DEET based preparation be washed off after it is no longer needed or between applications.^[2] In rare cases, it may cause skin reactions.
The American Academy of Pediatrics found no difference in safety for children, between products containing 10% and 30% DEET, when used as directed, but recommends that DEET not be used on infants less than two months old.
The Pesticide Information Project of Cooperative Extension Offices of Cornell University states that "Everglades National Park employees having extensive Deet exposure were more likely to have insomnia, mood disturbances and impaired cognitive function than were lesser exposed co-workers". ^[3]

Effects on materials

DEET is an effective solvent which may dissolve (part of) some plastics, rayon, spandex, other synthetic fabrics, leather, and painted or varnished surfaces.

Effects on the environment

Although few studies have been conducted to assess possible effects on the environment, DEET is a moderate chemical pesticide and may not be suitable for use in and around water sources. Though DEET is not expected to bioaccumulate, it has been found to have a slight toxicity for coldwater fish such as the rainbow trout^[4] and the tilapia ^[5], and it has also been shown to be toxic for some species of freshwater zooplankton.^[6] DEET has been detected in significant levels in waterbodies as a result of production and use, such as in the Mississippi River and its tributaries, where a 1991 study detected levels varying from 5 to 201 ng/L ^[7]

Natural alternatives

Some essential oil based insect repellents offer an alternative to DEET. While some are not as effective as DEET,^[8][9] research shows that other essential oil based formulas are comparable to DEET, and somewhat better.^[10]
Citronella oil, has been used as an insect repellent for over 50 years.^[11] Its mosquito repellency qualities have been verified by research,^[12] including repelling ''Aedes aegypti''. ^[13][14]
Catnip is marketed as a product against mosquito bites, but this product does not significantly reduce mosquito bites.^[15]

References

★ Mosquitoes and Mosquito Repellents: A Clinician's Guide, M. S. Fradin, , , Ann Intern Med, 1998
1.
2. Insect Repellent Use and Safety
3. http://pmep.cce.cornell.edu/profiles/extoxnet/carbaryl-dicrotophos/deet-ext.html
4. U.S. Environmental Protection Agency. 1980. Office of Pesticides and Toxic Substances. N,N-diethyl-m-toluamide (Deet) Pesticide Registration Standard. December, 1980. 83 pp.
5. Acute toxicity of deet to a freshwater fish, Tilapia mossambica : Effect on tissue glutathione levels., Mathai, AT; Pillai, KS; Deshmukh, PB, , , Journal of Environmental Biology, 1989
6. Biodegradation of the Insecticide N,N-Diethyl-m-Toluamide by Fungi: Identification and Toxicity of Metabolites, J. Seo, Y. G. Lee, S. D. Kim, C. J. Cha, J. H. Ahn and H. G. Hur, , , Archives of Environmental Contamination and Toxicology, 2005
7. Errol Zeiger, Raymond Tice, Brigette Brevard, (1999) N,N-Diethyl-m-toluamide (DEET) [134-62-3] - Review of Toxicological Literature
8. Comparative Efficacy of Insect Repellents against Mosquito Bites, M. S. Fradin and J. F. Day, , , N Engl J Med, 2002
9. Assessment of the efficacy of Quwenling as a Mosquito repellent, Collins, D.A., , , Phytotherapy Research, 1993
10. ''Laboratory and field trial of developing medicinal local Thai plant products against four species of misquito vectors'', Trongtokit Y., , , Southeast Asia J, Trop Med Public Health, 2004
11. Citronella (Oil of Citronella) (021901) Fact Sheet
12. Evaluation of Repellency Effect of Two Natural Aroma Mosquito Repellent Compounds, Citronella and Citronellal, Jeong-Kyu KIM, Chang-Soo KANG, Jong-Kwon LEE, Young-Ran KIM, Hye-Yun HAN, Hwa Kyung YUN, , , Entomological Research, 2005
13. Ibrahim Jantan, and Zaridah Mohd. Zaki, ''Developemnt of environment-friendly insect repellents from the leaf oils of selected Malaysian plants'', ASEAN Review of Biodiversity and Environmental Conservation (ARBEC), May 1998.
14. Comparative repellency of 38 essential oils against mosquito bites, Trongtokit Y, Rongsriyan Y, Komalamisra N, Apiwathnasom L, , , Phytother Res., 2005
15. Feeding Deterrent Effects of Catnip Oil Components Compared with Two Synthetic Amides Against Aedes aegypti, Chauhan, K.R., , , Journal of Medical Entomology, 2005

See also

★ Beautyberry

★ Icaridin

★ Permethrin, a pyrethroid

★ Citronella oil

External links

★ US Centers for Disease Control information on DEET

★ US Environmental Protection Agency information on DEET

★ Review of scientific literature on DEET (from a RAND Corporation report on Gulf War illnesses)