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Revision as of 15:06, 23 September 2008

Template:Chembox new N,N-Diethyl-meta-toluamide, abbreviated DEET, is the most common active ingredient in insect repellents. It is intended to be applied to the skin or to clothing, and is primarily used to protect against arthropod bites. In particular, DEET protects against tick bites (which transmit Lyme disease, several rickettsioses, tick-borne meningoencephalitis and other tick-borne diseases) and mosquito bites (which transmit dengue fever, West Nile virus, Eastern Equine Encephalitis, and malaria).

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. Originally tested as a pesticide on farm fields, the US Government applied it for war time usage, particularly when in Vietnam and around that region of Asia.

Mechanism of action

DEET was historically believed to work by blocking insect olfactory receptors for 1-octen-3-ol, a volatile substance that is contained in human sweat and breath. The prevailing theory was that DEET effectively "blinds" the insect's senses so that the biting/feeding instinct is not triggered by humans or animals which produce these chemicals. DEET does not appear to affect the insect's ability to smell carbon dioxide, as had been suspected earlier.[1][2]

However, more recent evidence shows that DEET acts as a true repellant that acts because it is unpleasant to the insect: A type of olfactory receptor neurons in special antennal sensilla of mosquitoes has been identified that is activated by DEET as well as other known insect repellants such as eucalyptol, linalool, and thujone. Moreover, in a behavioural test DEET had a strong repellant activity in the absence of body odor attractants such as 1-octen-3-ol, lactic acid, or carbon dioxide and female and male mosquitoes showed the same response.[3][4]

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: boiling point 111°C at 1 mm Hg.[citation needed]

Concentrations

DEET is available in many insect repellents
Besides Off, Autan and Care Plus also make DEET mosquito lotions

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.[5] Other research has corroborated the effectiveness of DEET.[6] The Center for Disease Control recommends 30-50% DEET to prevent the spread of pathogens carried by insects.[citation needed]

Effects on health

As a precaution, manufacturers advise that DEET products should not be used under clothing or on damaged skin, and that preparations be washed off after they are no longer needed or between applications.[7] DEET can act as an irritant;[1] in rare cases, it may cause skin reactions.[7]

In the DEET Reregistration Eligibility Decision (RED), the EPA reported 14 to 46 cases of potential DEET-associated seizures, including 4 deaths. The EPA states: " ..it does appear that some cases are likely related to DEET toxicity," but observed that with 30% of the US population using DEET, the likely seizure rate is only about one per 100 million users.[8]

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". [9]

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.[7]

Effects on materials

DEET is an effective solvent,[1] and may dissolve (part of) some plastics, rayon, spandex, other synthetic fabrics, leather, and painted or varnished surfaces including nailpolish.

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.[citation needed] Though DEET is not expected to bioaccumulate, it has been found to have a slight toxicity for coldwater fish such as the rainbow trout[10] and the tilapia,[11] and it has also been shown to be toxic for some species of freshwater zooplankton.[12] 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. [13]

Alternatives

Studies have shown eucalyptus-based repellents which contain the natural oil eucalyptol to be a highly effective and nontoxic alternative to DEET.[14] Also, plants such as lemon grass have proven effective against mosquitos.

Icaridin is another insect repellent of strength comparable to DEET, but it is less irritating and doesn't dissolve plastics.[15]

A test of various marketed insect repellents by an independent consumer organization found that synthetic repellents, including DEET, were more effective than repellents with ‘natural’ active ingredients. All the synthetics gave almost 100% repellency for the first 2 hours, whereas the natural repellent products tested were most effective for the first 30-60 minutes and then required reapplication to be effective over several hours.[16]

Citronella oil has been used as an insect repellent for 60 years.[17] Its mosquito repellency qualities have been verified by research,[18] [19][20] however, the repellency duration of DEET is much greater.[21] While most essential oil based repellents are not as effective as DEET,[21][22] research also shows that some essential oil based formulas can be comparable to DEET, and somewhat better specifically as mosquito repellant. [23]

Research suggests that distilled nepetalactone, the active ingredient in catnip, repels mosquitoes ten times more effectively than DEET,[24] but that it is not as effective a repellent on skin.[25]

See also

References

  • M. S. Fradin (1998). "Mosquitoes and Mosquito Repellents: A Clinician's Guide". Ann Intern Med. 128 (11): 931–940. PMID 9634433.
  1. ^ a b c Anna Petherick (2008-03-13). "How DEET jams insects' smell sensors". Nature News. Retrieved 2008-03-16.
  2. ^ Mathias Ditzen, Maurizio Pellegrino, Leslie B. Vosshall (2008). "Insect Odorant Receptors Are Molecular Targets of the Insect Repellent DEET". Sciencexpress. 319: 1838. doi:10.1126/science.1153121. PMID 18339904.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ For mosquitoes, DEET just plain stinks (Boston Globe)
  4. ^ "Mosquitoes smell and avoid the insect repellent DEET". Proc. Natl. Acad. Sci. U S A. 2008. doi:10.1073/pnas.0805312105. PMID 18711137.
  5. ^ Matsuda, Brent M.; Surgeoner, Gordon A.; Heal, James D.; Tucker, Arthur O.; Maciarello, Michael J. (1996). "Essential oil analysis and field evaluation of the citrosa plant "Pelargonium citrosum" as a repellent against populations of Aedes mosquitoes". Journal of the American Mosquito Control Association. 12 (1): 69–74.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ^ David Williamson (3 July 2002). "Independent study: DEET products superior for fending off mosquito bites" (Press release). University of North Carolina. {{cite press release}}: Check date values in: |date= (help)
  7. ^ a b c "Insect Repellent Use and Safety". West Nile Virus. Centers for Disease Control and Prevention. 2007-01-12.
  8. ^ "Reregistration Eligibility Decision: DEET." U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances. September 1998. pp39-40
  9. ^ "DEET". Pesticide Information Profile. EXTOXNET. October 1997. Retrieved 2007-09-26.
  10. ^ 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.
  11. ^ Mathai, AT; Pillai, KS; Deshmukh, PB (1989). "Acute toxicity of deet to a freshwater fish, Tilapia mossambica : Effect on tissue glutathione levels". Journal of Environmental Biology. 10 (2): 87–91.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ J. Seo, Y. G. Lee, S. D. Kim, C. J. Cha, J. H. Ahn and H. G. Hur (2005). "Biodegradation of the Insecticide N,N-Diethyl-m-Toluamide by Fungi: Identification and Toxicity of Metabolites". Archives of Environmental Contamination and Toxicology. 48 (3): 323–328. doi:10.1007/s00244-004-0029-9.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ^ "Errol Zeiger, Raymond Tice, Brigette Brevard, (1999) N,N-Diethyl-m-toluamide (DEET) [134-62-3] - Review of Toxicological Literature" (PDF). Retrieved July 20. {{cite web}}: Check date values in: |accessdate= (help)
  14. ^ "The Claim: Listerine Can Ward Off a Swarm of Mosquitoes". Several studies, including one by the London School of Hygiene and Tropical Medicine, have found that eucalyptus-based repellents can be extremely effective, and nontoxic to humans. {{cite news}}: Cite has empty unknown parameter: |coauthors= (help)
  15. ^ Picaridin
  16. ^ "Test: Mosquito repellents". CHOICE. December 2005. Retrieved 2007-09-26.
  17. ^ "Citronella (Oil of Citronella) (021901) Fact Sheet". U.S. Environmental Protection Agency. November 1999. Retrieved July 20. {{cite web}}: Check date values in: |accessdate= (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  18. ^ Jeong-Kyu KIM, Chang-Soo KANG, Jong-Kwon LEE, Young-Ran KIM, Hye-Yun HAN, Hwa Kyung YUN (2005). "Evaluation of Repellency Effect of Two Natural Aroma Mosquito Repellent Compounds, Citronella and Citronellal". Entomological Research. 35 (2): 117–120. doi:10.1111/j.1748-5967.2005.tb00146.x.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  19. ^ Ibrahim Jantan, and Zaridah Mohd. Zaki, Development of environment-friendly insect repellents from the leaf oils of selected Malaysian plants, ASEAN Review of Biodiversity and Environmental Conservation (ARBEC), May 1998.
  20. ^ Trongtokit Y, Rongsriyan Y, Komalamisra N, Apiwathnasom L (2005). "Comparative repellency of 38 essential oils against mosquito bites". Phytother Res. 19 (4): 303–9. doi:10.1002/ptr.1637.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ^ a b M. S. Fradin and J. F. Day (2002). "Comparative Efficacy of Insect Repellents against Mosquito Bites". N Engl J Med. 347 (1): 13–18. doi:10.1056/NEJMoa011699. PMID 12097535.
  22. ^ Collins, D.A. (1993). "Assessment of the efficacy of Quwenling as a Mosquito repellent". Phytotherapy Research. 7 (1): 17–20. doi:10.1002/ptr.2650070106. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  23. ^ Trongtokit Y. (2004). "Laboratory and field trial of developing medicinal local Thai plant products against four species of mosquito vectors". Southeast Asia J, Trop Med Public Health. 35 (2): 325–33. PMID 15691131. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: extra punctuation (link)
  24. ^ Dennis Loney (2001-08-28). "Mosquito Repellents". American Chemical Society. Retrieved 2007-08-28. {{cite web}}: Check date values in: |date= (help)
  25. ^ Chauhan, K.R. (2005). "Feeding Deterrent Effects of Catnip Oil Components Compared with Two Synthetic Amides Against Aedes aegypti". Journal of Medical Entomology. 42 (4): 643–646. doi:10.1603/0022-2585(2005)042[0643:FDEOCO]2.0.CO;2. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |doi_brokendate= ignored (|doi-broken-date= suggested) (help)

External links

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