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[pct-l] Deet 20% or 100%



fwiw,
hiked 26 miles through tick area this weekend and went crazy flicking off 
ticks after using 100% deet on ankles (under long pants in spite of the warm 
days) and all exposed areas.  Still, my husband and I each found a tick on 
our bottoms unnoticed at the end of the day, and he had one imbedded in his 
thigh and one in his armpit.  Not good.  Second day we made ourselves 
paranoid with tick checks every 15-30 minutes and every snack/breath break 
(steep hills).  Third day we wised up and used the rest of our spray bottle 
of deet to cover our whole pants and sleeves with the spray in addition to 
ankles and exposed skin and we didn't have a single tick all day except one 
on my pants leg that jumped/fell off immediately.  Hiked the rest of the day 
on narrow trail happily and found ourselves not even checking anymore for 
long periods of time.  Made us decide to stick to light colored clothing and 
spray the dickens onto our trail clothes at the parking lot next time.  (We 
don't wear the same clothes to sleep.) But in tick country, gotta make sure 
to not need to go pee in the night!  Those little guys are invisible in the 
dark!  My husband spent time in the doctor's office today getting the heads 
cut out and picking up antibiotics.  Increases the cost of the weekend 
considerably!
Just a trail prep thought... I don't know which areas of the PCT are 
tick-infested.
Kim


From: The Mountain Goat <themtgoat@yahoo.com>
To: pct mailing list <pct-l@mailman.backcountry.net>
Subject: [pct-l] Deet 20% or 100%
Date: Mon, 13 Feb 2006 21:17:32 -0800 (PST)


It may be true that deet works good with 20% and that below that
the bloody thirsty varments may start to attack. But the 20-30%
in some trail tests in the late 1990's with my hiking companions
as unsuspecting test canidates, found that it was good for no more than
30 minutes, the 100% seemed to work for about 1 hour. sometime a litte
longer.

Good Luck to the Class of 06. I wish I could join you.
-Mountain Goat-




[pct-l] Deet     Jerry Goller      jerrygoller at backpackgeartest.org
      Wed Feb  8 13:55:02 CST 2006
---------------------------------

Interesting. According to the military's own research, concentrations of
DEET above 30% did not increase effectiveness. What did increase it was
timed release. The military developed a polymer based controlled released
formula that successfully addressed the break down issue and is available
commercially as 3M Ultrathon (just over 30% concentration) in both a cream
and a spray. Sawyer Controlled Release is a similar product with a
concentration of about 20%.

The reason that 100% appears to work better is that DEET starts to break
down as soon as it is applied to the skin. It continues to break down until
it completely loses it's ability to repel, which is below 20%. Obviously, it
takes 100% longer to break down than it does 30%.

With controlled release DEET the DEET is encapsulated in a polymer at
"protects" the DEET molecules from breaking down. The polymers are
formulated to break down at different rates therefore allowing a constant
concentration of between 20 and 30%, depending on the brand, over a much
longer time period. Protection over 12 hours or greater is very common. I
only apply it once a day.

Now I will agree that in very high concentrations of particularly aggressive
mosquitoes it is possible that augmentation with 100% concentration could be
beneficial. I've not run into that yet, but have read about it.

This system last longer than 100% DEET, is resistant to dilution by
sweating, is much more comfortable to wear, and it also tends to limit
dermal absorption of the DEET.

We tested both products on BGT.


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