Some interesting stuff courtesy of OUTDOORSmagic member Ben
Brockway who took time out from the ghastly horrors of New Zealand to
put together this article:
Hot news from the New England
Journal of Medicine - generally regarded as one of the best
medical journals in the world. According to a large study into the
effectiveness of a variety of insect repellants, DEET based
repellents are still by far the best. The
study also included Avon's 'Skin So Soft', an old favourite of
fragrant hillwalkers everywhere.
Those crazy kids from the Florida Medical Entomology laboratory
tested various concentrations of DEET, IR3535, Skin So Soft ,
citronella and impregnated wristbands. Foolhardy volunteers put their
arms in cages of hungry mosquitos (fortunately proven to be clean
living, disease free mozzies rather than malarial ones...).
Stunt Forearm...
Just to make sure the mozzies were awake an untreated stunt
forearm was also put in the cage - presumably still attached to
volunteer- until bitten five times, then the test forearms were
inserted. And the study showed that DEET still rules the roost. 5%
DEET gave protection for about 88 minutes while 24% gave protection
for a whopping 300 minutes.
The best non-DEET product, based on soya-bean oil, managed to keep
up with the feeblest DEET formula, but after that there was little
hope for the volunteers. Citonella and Skin-So-Soft lasted for 10-20
minutes at best, and the impregnated wristbands gave a heady 12 to 18
seconds protection only!
So what does it all mean? Well, bear in mind this was a study
involving Aedes Aegypti, a mosquito that carries malaria, the West
Nile virus, and assorted viral encepahlitides that can cause havoc on
the brain in the US. It didn't involve those particularly annoying
midges that congregate out the back of the Kingshouse and other
closer-to-home areas. So we still don't know if Skin-So-Soft works in
Scotland, other than to make you smell better after a long day on the
hill.
DEET Rules Okay
But for travel in malarial areas, high concentration DEET is the
way forward - along with mozzie nets and hats if you can face them.
Other research has shown the amount of extra protection from DEET
concentrations above 40-50% is minimal, and garlic eating doesn't
help repel mozzies, only other humans. Ultrasonic mozzie scarers are
totally ineffective. The study also looked at newer eucalyptus oil
based repellants and these had encouraging results, but still not up
to the level of DEET.
And how safe is DEET? Well, it's not great stuff - it melts holes
in map cases, watches and spectacles, so what effect does it have on
your skin? The authors point out that it's been in use for 40 years -
estimating 8 billion human applications - with about 50 recorded
cases of toxicity; 75% of these resolving completely. So a 12 in 8
billion recorded incidence of adverse effects doesn't seem too bad,
and these cases all involved long term, whole body usage of high
concentration DEET.
Of course the best way to avoid catching malaria is still to go on
holiday to Scunthorpe, but where's the fun in that?
ben brockway
