Bronstein
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Mosquito repellants (2-ethyl-1,3-hexanediol)
Where I live there used to be this mosquito repellant that contained 2-ethyl-1,3-hexanediol. Later it was banned, and it has since come to have an
almost legendary status as the ultimate insect repellant. Nothing nowadays could beat it people use to say.
I understand there are some places where they still use this, can anyone of you tell me if it's really that good? I have considered buying the pure
chemical (it's actually pretty cheap) and making up some of my own mosquito repellant, but it would be interesting to know before hand if it's really
as good as they say. Or if it's just like fishing stories, it gets better and better for each person that tells the story.
I guess it might make a difference depending on the particular variety of mosquitoes in the different countries though.
[Edited on 2-6-2008 by Bronstein]
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JohnWW
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Here in New Zealand, there are 6 native species of mosquito, some of which are believed to be also found in Australia. A few years ago, the Australian
salt marsh mosquito, which carries a virus, found its way here, either in used tires or by being simply blown over, and attempts are being made to
find and eradicate infestations.
For many years, DIMP, or dimethyl phthalate, was the only mosquito repellant here, sold as a wipe-on product. Then, while retaining the brand-name
DIMP, it was replaced with a solution of N,N-diethyltoluamide, in an aerosol spray-can, available in pharmacies and supermarkets. This cost much more,
but was no more effective. The genuine dimethyl phthalate seems to be unobtainable, except possibly from induistrial chemical suppliers. The present
most prominent brands now sold here (both manufactured in Australia) are Aerogard, as a pump-spray containing 92.8 g/l of picardin (or icaridin) in
either isopropanol or methylated (denatured) spirits with possibly a small amount of acetone, and Off! Skintastic, an aerosol spray containing 191 g/l
of N,N-diethyltoluamide (as above), 40 g/kg of di-n-propyl isocinchomeronate, and 20 g/l of n-octyl-bicycloheptene dicarboximide, probably also
dissolved in either isopropanol or methylated spirits with some acetone added. While they are effective, they are outrageously priced, and do not seem
to be any more effective than the old dimethyl phthalate.
[Edited on 3-6-08 by JohnWW]
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Sauron
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The mosquito repellant I remember from my childhood in New Orleans in the 50s was an oily topical liquid sold under the brand names Formula 612 or
Skeetol. I do not remember its chemical composition. My recollection was that it was a WWII development.
Exactly why was 2-ethyl-1,3-hexanediol banned?
The most common mosquito-borne virus is dengue while obviously the most troublesome parasite with a mosquito vector is the plasmodium responsible for
faciparum malaria, which can be fatal and which is so resistant to treatment.
Sic gorgeamus a los subjectatus nunc.
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-jeffB
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| Quote: | Originally posted by Sauron
The mosquito repellant I remember from my childhood in New Orleans in the 50s was an oily topical liquid sold under the brand names Formula 612 or
Skeetol. I do not remember its chemical composition. My recollection was that it was a WWII development. |
Hmm... I see Skeetol listed as a brand name for BT biological control, and Formula 612 listed as an algaecide/fungicide/microbicide:
http://www.scorecard.org/chemical-profiles/product.tcl?reg_n...
As far as I've seen, DEET is the gold standard for mosquito repellents, significantly more effective than anything before or since. Picaridin is
about equally effective, but not as persistent -- you need to reapply more frequently, and, of course, it's more expensive. It's worth it for me,
though, as picaridin is not an aggressive solvent like DEET (which will eat straight through auto paint, synthetic fabrics, and laptop finishes). It
also doesn't reek like DEET.
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not_important
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2-ethyl-1,3-hexanediol is a skin irritant, and the US manufacture Union Carbide reported indications of it causing birth defects. It indeed was the
oily stuff making up Formula 612, also known simply as 6-12.
Phthalate diesters have endocrinological activity, specifically estrogen-like ones. I suspect the military was not too keen on the possibility of
needed to supply their troops with C and D cups.
In a number of studies DEET was found to be the most effective repellent. Many of these studies were done by various national military of health
agencies, in some cases including 6-12 and/or DMP in the study.
One thing that may influence the selection of repellents is evidence of inherited tolerance of them
| Quote: | | Certain inbred strains differed significantly from cognate laboratory and/or inbred strains in tolerance to one or more test materials. Heritability
in the broad sense (H2) was estimated at 0.05 for deet, 0.22 for ethyl hexanediol, 0.48 for dimethyl phthalate, and 0.51 for Indalone.
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http://www.ncbi.nlm.nih.gov/pubmed/8014634?ordinalpos=1&...
If I'm reading that correctly, DMP is rather susceptible to acquired resistance and 6-12 moderately so, while DEET is much less so.
If I'm remembering correctly, these repellents don't repell so much as 'jam' the insects CO2/H2O sensing, so that they can no longer follow the
gradient back to the animal but instead must depend on drunkards-walk luck.
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JohnWW
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DEET is N,N-Diethyl-meta-toluamide, which I mentioned above; see http://en.wikipedia.org/wiki/DEET .
As for DIMP and other phthalate diesters having estrogenic activity, there must be other volatile aromatic esters, not being estrogenic, that also
repel mosquitos by "jamming" their ability to detect CO2 (and other substances emitted by bodies - they seem to go for bare skin, so they must also
detect heat and substances in perspiration, such as some medium-length branched-chain alcohols). I wonder if, for example, methyl or ethyl benzoate,
or esters of the benzenedicarboxylic acids other than phthalic acid, or methyl or ethyl esters of the isomeric methyl- or ethyl-benzoic acids have
been tried. They are likely to be cheaper to make than N,N-Diethyl-meta-toluamide.
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Sauron
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How the hell did they light on the acronyl DEET? The second E is superfluous for N,N-Diethyl-m-toluamide.
So the repellant of my youth was the 2-ethyl-1,3-hexanediol. I do not remember it being at all irritating. It had a smell, but not an unpleasant one.
Sic gorgeamus a los subjectatus nunc.
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unionised
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Citronella oil anyone? Not brilliantly effective but it smells nice.
Most of the phthalates aren't endocrine disruptors but bandwaggon politics got rid of all of them. If it turns out that they are really a problem then
the Western world is doomed- for many years they were massively used as plasticisers for PVC etc. Just the thing for baby toys- soft and washable (and
chewy - ask any baby).
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Sauron
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As I recall, dibutyl phthalate is the specific scent involved in canine estrus.
So I would not advise using that ester as a mosquito repellant, unless you want to be very popular with any male dogs that happen to be around.
Sic gorgeamus a los subjectatus nunc.
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JohnWW
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Another fairly cheap aromatic ester that could be investigated for mosquito-repelling properties is methyl salicylate, the major constituent of oil of
wintergreen.
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not_important
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Methyl salicylate has the disadvantage that it is absorbed through the skin to some extent, which can lead to salicylate toxicity. This is especially
true if aspirin is also taken, as that gives a fairly high level in the blood. People using anti-coagulants also need to be careful.
http://www.medscape.com/viewarticle/448275_side1
http://seattletimes.nwsource.com/html/nationworld/2003741058...
http://cat.inist.fr/?aModele=afficheN&cpsidt=3252385
and guys - think twice
http://meeting.chestjournal.org/cgi/content/abstract/132/4/7...
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Sauron
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Ouch.
A little dab WILL do you.
Sic gorgeamus a los subjectatus nunc.
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