 | |
 | |
| Names | |
|---|---|
| Preferred IUPAC name N,N-Diethyl-3-methylbenzamide | |
| Other names N,N-Diethyl-m-toluamide | |
| Identifiers | |
| |
3D model (JSmol) | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
|
| ECHA InfoCard | 100.004.682 |
| KEGG |
|
| UNII | |
| |
| |
| Properties | |
| C12H17NO | |
| Molar mass | 191.27 g/mol |
| Density | 0.998 g/mL |
| Melting point | −33 °C (−27 °F; 240 K) |
| Boiling point | 288 to 292 °C (550 to 558 °F; 561 to 565 K) |
| Pharmacology | |
| P03BX02 (WHO) QP53GX01 (WHO) | |
| Hazards | |
| GHS labelling: | |
 | |
| Danger | |
| H302,H315,H319,H402 | |
| NFPA 704 (fire diamond) | |
| Safety data sheet (SDS) | External MSDS |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
N,N-Diethyl-meta-toluamide, also calleddiethyltoluamide orDEET (/diːt/, from DET, the initials of di- + ethyl + toluamide),[1][2] is the oldest, one of the most effective, and most common active ingredients in commercialinsect repellents. It is a slightly yellow oil intended to be applied to theskin or toclothing and provides protection againstmosquitoes, flies,ticks,fleas,chiggers,leeches, and many other biting insects.
DEET is effective against a variety of invertebrates, including ticks, flies, mosquitos, and some parasitic worms.[3]
A 2018 systematic review found no consistent performance difference between DEET andicaridin infield studies and concluded that they are equally preferred mosquito repellents, noting that 50% DEET offers longer protection but is not available in some countries.[4]
The concentration of DEET in products may range from less than 10% to nearly 100%, but concentrations greater than 50% do not increase the duration of protection.[5] Higher concentrations can be safely applied to clothing, although it may damage some types of synthetic fibers. In the United Kingdom, the publicly-funded healthcare system, theNational Health Service (NHS), recommends that UK citizens should use a concentration of 50% when visiting areas of the world withmalaria.[6] A lower concentration of 10% is recommended for infants and children.[7][8]Health Canada decided to limit DEET concentration to 30% in the country since 2002 due to an increased long-term risk observed with repeated applications.[9]
DEET is often sold and used in spray or lotion in concentrations up to 100%.[10]Consumer Reports report acorrelation between DEET concentration and hours of protection against insect bites, but not how effective the protection is.[11] Other research has corroborated the effectiveness of DEET as an insect repellent.[12] TheCenters for Disease Control and Prevention (CDC) recommends 30–50% DEET to prevent the spread of pathogens carried by insects.[13]
A 2008 study found that higher concentrations of DEET have an improved ability to repel insects through fabric.[14]
The CDC recommends that DEET should not be used on children younger than 2 months of age.[15]
When used as directed, products containing between 10% and 30% DEET have been found by theAmerican Academy of Pediatrics to be safe to use on children as well as adults.[15]
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.[15] DEET can irritate the eyes and, unlikeicaridin, it can cause breathing difficulty,headaches,[16] or, in rare cases, it may cause severeepidermal reactions.[15]
The authors of a 2002 study published inThe New England Journal of Medicine wrote:[17]
... this repellent has been subjected to more scientific and toxicologic scrutiny than any other repellent substance. ... DEET has a remarkable safety profile after 40 years of use and nearly 8 billion human applications. Fewer than 50 cases of serious toxic effects have been documented in ... medical literature since 1960 ... Many of these cases of toxic effects involved long-term, heavy, frequent, or whole-body application of DEET. No correlation has been found between the concentration of DEET used and the risk of toxic effects. ... When applied with common sense, DEET-based repellents can be expected to provide a safe as well as a long-lasting repellent effect ... under circumstances in which it is crucial to be protected against arthropod bites that might transmit disease.
In the DEET Reregistration Eligibility Decision (RED) in 1998, theUnited States Environmental Protection Agency (EPA) reported 14 to 46 cases of potential DEET-associatedseizures, including four deaths. The EPA states: "... it does appear that some cases are likely related to DEETtoxicity," which may underreport the risk as physicians may fail to check for history of DEET use or fail to report cases of seizure subsequent to DEET use.[18]
In 1997, the Pesticide Information Project of Cooperative Extension Offices ofCornell University stated that "Everglades National Park employees having extensive DEET exposure were more likely to haveinsomnia, mood disturbances and impairedcognitive function than lesser exposed co-workers".[19]
Citing human health reasons,Health Canada barred the sale of insect repellents for human use that contained more than 30% DEET in a 2002 re-evaluation "based on a human health risk assessment that considered daily application of DEET over a prolonged period of time". The agency recommended that DEET-based products be used on children between the ages of 2 and 12 only if theconcentration of DEET is 10% or less and that repellents be applied no more than 3 times a day, children under 2 should not receive more than 1 application of repellent in a day and DEET-based products of any concentration should not be used on infants under 6 months.[20][21]
A 2020 study performed by students within theUniversity of Florida's College of Public Health and Health Professions analyzed data from the National Health and Nutrition Examination Survey and identified 1,205 participants who had "DEET metabolic levels recorded at or above detection limits". They analyzedbiomarkers related to systemic inflammation, immune, liver, and kidney functions, and found no "evidence that DEET exposure has any impact on the biomarkers identified."[22]
DEET may be measured in blood, plasma, or urine bygas orliquid chromatography-mass spectrometry to confirm a diagnosis of poisoning in hospitalized patients or to provide evidence in a medicolegal death investigation. Blood or plasma DEET concentrations are expected to be in a range of 0.3–3.0 mg/L during the first 8 hours after dermal application in persons using the chemical appropriately, >6 mg/L in intoxicated patients and >100 mg/L in victims of acute intentional oral overdose.[23][24]
Applying DEET to the skin is safe if done as directed. Adverse reactions are very rare, about 1 in 100 million people. However, repeated use of DEET in very high concentrations can lead totoxic encephalopathy with severe neurological symptoms including seizures, tremors and slurred speech. The risk is higher for children since they have a greater surface area to body weight ratio.[25][26]
Limited data indicates that combining insect repellents with DEET and sunscreen decreases the sun protection factor of the sunscreen by about a third.[27] Unlikeicaridin, the combination also increases the absorption of both significantly.[28] When the two need to be used together, the repellent should be applied after the sunscreen has been absorbed, about 30 or more minutes later.[29]
When DEET is used in combination with insecticides forcockroaches it can strengthen the toxicity ofcarbamate, anacetylcholinesterase inhibitor. These 1996 findings indicate that DEET hasneurological effects on insects in addition to knownolfactory effects, and that its toxicity is strengthened in combination with other insecticides.[30]
Unlikeicaridin, DEET is an effectivesolvent[31] and may dissolve some watch crystals,[32] plastics,rayon,spandex, othersynthetic fabrics, and painted orvarnished surfaces including nail polish. It also may act as aplasticizer by remaining inside some formerly hard plastics, leaving them softened and more flexible. DEET is incompatible with rayon,acetate, ordynel clothing.[33]
Though DEET is not expected tobioaccumulate, it has been found to have a slighttoxicity for fresh-waterfish such asrainbow trout[34] andtilapia,[35] and it also has been shown to be toxic for some species of freshwaterzooplankton.[36] DEET has been detected at low concentrations in water bodies as a result of production and use, such as in theMississippi River and its tributaries, where a 1991 study detected levels varying from 5 to 201ng/L.[37]
A 1975 study analyzed the effects of DEET on communities of freshwater organisms native to Chinese waterways and found that DEET was moderately toxic to aquatic organisms compared to other commercial insect repellants. The most-at-risk organisms werealgae colonies which often experienced "significant biomass decline and community composition shift[s]" when exposed to DEET at 500 ng/L.[38]
DEET isbiodegraded by fungi into products less toxic to zooplankton.[36] It degrades well underaerobic conditions, but poorly and slowly under anaerobic conditions.[39]
DEET is thought to provide protection from mosquitos via two pathways, both by negatively impacting mosquitoodorant receptors at a distance, and by negatively impacting mosquitochemoreceptors upon contact.[3] The exact mechanisms are still being researched, but the two most likely hypotheses are the "smell and avoid hypothesis" (that DEET has an unpleasant odor to insects), and the "bewilderment hypothesis" (that smelling DEET confuses insects).[3] An alternative hypothesis is that DEET "masks" humans by reducing the volatility of skin odorants that are attractive to insects.[40]
A slightly yellow liquid atroom temperature, it can be prepared by convertingm-toluic acid (3-methylbenzoic acid) to the correspondingacyl chloride usingthionyl chloride (SOCl2), and then allowing that product to react withdiethylamine:[41][42]
DEET was developed in 1944[43] by Samuel Gertler[43] of theUnited States Department of Agriculture for use by theUnited States Army,[44] following its experience ofjungle warfare duringWorld War II. It was originally tested as a pesticide on farm fields, and entered military use in 1946 and civilian use in 1957. It was used inVietnam and Southeast Asia.[45]
In its original form, known as "bug juice", the application solution was composed of 75% DEET and 25% ethanol.[32] Later, a new version of the repellent was developed by the U.S. Army and the USDA. This formulation consisted of DEET and a mixture of polymers that extended its release and reduced its evaporation rate.[46] This extended-release application was registered by theEnvironmental Protection Agency in 1991.[32]
{{cite journal}}: CS1 maint: multiple names: authors list (link){{cite journal}}: CS1 maint: multiple names: authors list (link)
