NR, N-diéthyl-3-méthylbenzamide

See also: DEET

The NR, N-diéthyl-3-méthylbenzamide , called before NR, N-diéthyl-m-toluamide , or DEET are chemicals known since the years 1950 like Répulsif against the Insecte S (presented according to the products like effective against mosquitos, chips, ticks, prickly fly of the cattle sheds and aoûtats.

It was used for the first time at the time of the Guerre of Vietnam, by American. It has a broad spectrum of action on different Insectes, but can start Allergies.

  • Number CASE: 134-62-3

  • molecular Formula: Molecular C12H17NO
  • Mass: 191,26

Marketed products

In 2001, it was for 37% of the aerosols under pressure; others being emulsions in water (22%) sold in the form of creams, gel or lotions. Three formulations were treated to have a " prolongé" effect; (mico-encapsulation, polymers…). Four formulas were sold in the form of impregnated paper towel of solutions of DEET, and one was a product in paste. 9% of the commercial preparations contained DEET not or very little diluted (95% to 100% of DEET according to the labels). Thirteen products contained also agents protecting from the sun in addition to the DEET.

Operation and effectiveness

It is thought that the DEET functions by blocking the Récepteurs insects (in particular those detecting carbon dioxide and the lactic acid) which are used to locate the hosts. The DEET plugs the directions of the insects making that the instinct of puncture/nourrissage is not started by the man or the animal who produce these compounds. According to the Canadian evaluation (see Notes), there is no evidence of the effectiveness of the DEET on the chips.

All the invertebrates stitchers are not also sensitive there: 50% of DEET are enough to move away Aedes aegypti during four hours, whereas 12,5% and 25% are enough against Aedes albopictus during respectively six and eight hours

Proportionings and duration of protection

An investigation of 1999 into the contents of the labels of insects repellant containing of the DEET showed that only 3% of the labels gave precise instructions of proportioning (e.g. “to apply 6 to 8 or 8 to 10 drops”, “to impregnate with the quantity recommended”, the majority of the labels being vague (e.g. “to apply in thin layer” or “to pulverize on clothing and the skin exposed”). 22% of the labels indicated the duration of protection precisely (of 1 with 8:00 against the mosquitos, on the skin, according to the products). 20% of the products vaguely specified a protection “during hours”), 19% recommending to apply according to the need and 36% not indicating anything whole to this point.

Commercial preparations

According to a Canadian study, at July 6th, 2001, one found 127 preparations commercial (PC) approved containing DEET, produced by 41 holders of homologation. They were always body insects repellant. In four cases, the DEET was associated with MGK Synergist 264 , and in 13 case with MGK Repellent 326 and the MGK Synergist 264.

Toxicity

This product is considered sure, but must thus be held with the variation of the children (to use with precaution between 6 months and 3 years, with concentration of 10% at the most, in the event of high-risk situations of complications following an insect bite, in only one application per day, and avoiding the applications on the face and the hands and any prolonged employment). It should not be used on the children of less than 6 months and in the expectant mothers. In the child from 2 to 12 years, only of the solutions with 10% maximum of DEET should be used, without prolonged employment, not more than 3 times per day and by avoiding the hands and the face. The products containing more than 30% of DEET will not be approved any more because of the health hazards related to a long-term daily application and because the weak concentrations were shown as effective as the preparations with strong concentration (they are only effective less a long time)

Cases of convulsions in the child were listed (at least 12 since the implementation of this product), without the origin of these convulsions being able to be charged to the product; it is thus there about a Precaution principle that some judge abusive. The DEET is partly absorbed by the skin (30%) according to the manufacturers and their studies.
Another undesirable effect of the DEET is that it attacks certain plastics and materials of synthesis.
Il should not be introduced nor pulverized on the mucous membranes and the eyes.

If the DEET is applied to concentration raised at the same time as a sun lotion, it strongly reduces the effectiveness of the latter.

Properties

External bonds

  • Note on the revaluation of the toxicity of the DEET)

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