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Diluting Deet?
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Konrad .
(Konrad1013) - MLife
Diluting Deet? on 02/19/2010 22:52:22 MST Print View

Hi guys, quick question regarding the use of Deet. So I managed to find a tiny non-aerosol spray bottle and was thinking of using it to repackage my bug repellent. I mainly use lemon eucalyptus, but have always been curious about deet. I purchased a 100% deet "juice" from rei when it was on clearance once, but have never gotten around to using it. I was wondering if its possible to dilute the deet with water, and use it as a spray with my new bottle.

To be honest, I don't even know how to use pure 100%deet, as my only previous experiences with deet is when its at a lower strength, and mixed in a aerosol can from company's like "deep woods". I know a little bit of pure deet goes a long way, and I've heard you don't necessarily need to cover all your exposed skin with it. Is this true?

And would mixing it with water, before applying hinder its effects?

Would i be better off just pouring in the 100% pure deet, into my spray bottle, and spraying it in a few location on my body?

Thanks for any input!

Edited by Konrad1013 on 02/19/2010 22:55:13 MST.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
DEET on 02/19/2010 23:05:45 MST Print View

I'm not sure that DEET will mix with water. You might try something more like alcohol. Full strength DEET ("jungle juice") became popular many moons ago when some of us were employed by the government in a far away place. I know that it dissolved the paint on my car!

Later, REI marketed something called Jungle Juice that was 71% DEET, and it was pretty effective also. A product called Repel 100 is 95% DEET.

Basically, you just want to get the stuff to vaporize and to create a cloud that hangs around you or your clothing, and that will keep the bugs away. You'll get a certain amount of that going by direct application to your skin, but then you'll suffer any possible toxic effects. For safety, I would generally apply it to my clothing, and then let my body heat vaporize it slowly from the clothing. You could apply it with a dropper if you had to, but you can get it spread thinner with an atomizer/sprayer.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
one followup on 02/19/2010 23:11:37 MST Print View

"REI marketed something called Jungle Juice that was 71% DEET"

I found the bottle and looked at the Inert Ingredients. Denatured Ethanol 25%.

I think that is what you need to use to cut it.


Konrad .
(Konrad1013) - MLife
Re: one followup on 02/19/2010 23:37:17 MST Print View

Perfect! Thanks Bob, thats exactly what i was looking for.

I've also had some mishaps with deet. Once melted my rubber/plastic watch strap when i accidently sprayed Deep Woods over it.. definitely worried me considering I would spray that stuff directly onto my skin.

Anyone experience bleaching of clothes b/c of deet?

Edited by Konrad1013 on 02/19/2010 23:38:25 MST.

Brandon Sanchez
(dharmabumpkin) - F

Locale: San Gabriel Mtns
DEET on 02/19/2010 23:49:03 MST Print View

I had DEET leak onto my red MSR fuel canister. It melted the red paint and got a red/pink gunk all over everything. Needless to say I dont put it on my face anymore.

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: Diluting Deet? Why? on 02/20/2010 00:13:09 MST Print View

Why dilute it? With 100% DEET, all you need are 4-6 drops of that stuff. With a dropper bottle, squeeze out:

o 1-2 drops for your face, ears, neck
o 1-2 drops for your legs
o 1-2 drops for your arms and hands

I can't think of any other bug product that's lighter to carry or faster/easier to apply.

I've read that 100% DEET can harm plastics and I do believe it can happen -- but I haven't experienced it at all personally.

Finally, if I remember correctly, DEET's been around since WWII -- it has been tested safe and used for over 60 years now.

Edited by ben2world on 02/20/2010 00:15:29 MST.

Brad Groves
(4quietwoods) - MLife

Locale: Michigan
Re: Diluting Deet? on 02/20/2010 10:21:02 MST Print View

I've seen a number of studies clearly showing that DEET is a known carcinogen. Combine that with the fact that the stuff has destroyed cameras, bike computers, and other things, and I've gotta really be in need to use it. Back in the day I did a number of "experiments" using 100% Deet and 30% Deet; I was in the same horrid, black fly/mosquito environment over the same period of days, and switched between the two products. I always had fewer bites and bothers using the 30% Deet... I like Ben's 30.

I spray it on the back of my hands, on the cuffs of my shirt, on the brim and crown of my hat. If the buzzies are really bad, I spritz some on my hand and dab a little Deet behind my ears and on my cheeks.

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: Diluting Deet? on 02/20/2010 10:26:39 MST Print View


I have better experience with 100% DEET (using just the 4-6 drops as directed) than lathering myself with 30% DEET lotion. I'm sure them skeeters and flies screwed around with the results on purpose -- to confuse you and me. :)

That said, I find Ultrathon (34% DEET) results more than good enough. For the last two years, I've mixed my Ultrathon and my REI sunblock together -- so half the weight, half the volume, and half the application time -- and the results are just as good as separate applications!

I was glad I experimented with mixing rather than taking "conventional wisdom" against mixing for granted!

Edited by ben2world on 02/20/2010 10:27:40 MST.

Dean F.
(acrosome) - MLife

Locale: Back in the Front Range
DEET on 02/20/2010 12:10:23 MST Print View

The DEET/carcinogen thing is urban myth and pseudoscience. (As best we know at the moment, that is...) I see that meme pop up with some frequency, and try to squash it where I can. It has an incredibly long and safe track record. CERTAINLY the risk of malaria, West Nile, Lyme disease, RM Spotted Fever, etc. FAR outweighs the risk from DEET.

DEET is primarily meant to be applied to skin, though assuming that your clothes didn't melt you would of course still benefit from applying it to clothing. Permethrin OTOH is meant to be applied to clothes, and lasts through several washings unlike DEET. I am incredibly familiar with both, being a military physician (gotta love those preventive medicine classes) and also having looked up a bunch of scientific articles about DEET a year or so ago during a similar forum discussion.

Yes, it is toxic (NOT carcinogenic) in large amounts. LARGE amounts. As with many insecticides and repellents it has a nerve-gas-like ability to inhibit acetycholinesterase. You'll know if you're using too much because you'll get twitchy kinda like you overconsumed caffeine (though the mechanism is somewhat different from that of caffeine). By far most cases of significant toxicity involved idiocy on the part of the user- and, yes, usually involved 100% DEET because it is easy to abuse in that concentration. I think a child died after drinking some, and it is possible that it might contribute to seizures in susceptible individuals. I recall that there have been a handful of fatal seizures in which DEET may have been a contributing factor- which is not an unreasonable hypothesis given its neurologic activity- but no one is really certain. So if you have a seizure disorder you should avoid it.

I, personally, stick to 'military-grade' 33% DEET.

Also, yes it will dissolve some plastics and other synthetics but generally once 'dried' on the skin you needn't worry about it rubbing off and melting something. Rayon, nail polish, and varnishes in particular are susceptible. I still wouldn't touch plastic eyeglass lenses, though, as I imagine that might be enough to form a hazy fingerprint etched into the lens. I have seen a pair of old Army RPG glasses melt when DEET was applied directly to them.

Don't let naturalpathic people scare you away from DEET. Yes, it is not very 'natural', so if that's your thing by all means avoid it. But it is also the only skin-safe insect repellent that has been proven to work well, notwithstanding the citronella and eucalyptus fanboys. (If nothing else, the natural stuff needs to be re-applied essetially continuously to have any effect.) If the natural stuff works for you, all the more power to you, Brother. But you simply can't beat DEET for effectiveness if you aren't otherwise opposed to it.

I have heard of another synthetic repellent called Icaridin that may have promise, but I'm unsure about studies verifying its effectiveness.

Edited by acrosome on 02/20/2010 12:47:43 MST.

Piper S.
(sbhikes) - F

Locale: Santa Barbara (Name: Diane)
Re: Re: Diluting Deet? on 02/20/2010 12:20:42 MST Print View

I was on the PCT in Oregon in July. I have never in my life experienced mosquitoes like that.

I carried a small Visine bottle with 100% DEET in it. It was an effective container, didn't melt, was easy to use, dispensed the DEET well. However, it wasn't enough DEET. I ended up buying a big can of Repel that I could spray on myself. 40% DEET. It seemed as effective as the 100% DEET, perhaps because it was easier to get it on my clothing and in an even application all over.

I will say that when I fogged my hat and head net with DEET, I would get a little dizzy and feel sick. I also noticed that when I spread the 100% DEET on the backs of my hands, the mosquitoes would bite the palms of my hands instead, even though I was holding trekking poles at the time. The mosquitoes in Oregon are nothing if not persistent.

I didn't have such difficult problems with California mosquitoes, nor with the Washington mosquitoes after the snow was gone. I think it's a special snow melt mosquito that is so awful, not the regular kind.

Anyway, I hope this was useful information.

Roman Dial
(romandial) - F - M

Locale: packrafting NZ
Re: Diluting Deet? on 02/20/2010 16:09:21 MST Print View

We have been diluting DEET for 20 years or so now. We use rubbing alcohol to stretch it when putting it in pump-spray bottles.

100% makes my lips numb if it gets near them and its greasyness is nasty (but makes a good lubricant in the field). So we like to cut it.

Alaska has some bad bugs. We did a trip in the Arctic Refuge in July once. I killed with one hand, one swat, no smearing on my pant leg on my shin -- wait for it -- 94 mosquitoes once. So when you are in really bad bugs see how many you can swat with one hand and count them and remember 94 is the record (unless someone has it beat out there?).

On that trip my 2 ounces of 100% DEET ran out in about 5 days....midway through the trip.

DEET also can be used as fire starter when applied to toilet paper, but the smoke seems nasty, so using DEET cut with alcohol is nicer to start fires.

My wife taught me to put DEET on the back of my hands and use that to apply, instead of the palms which then contaminate everything I touch (like food giving numb lips). Longish hair (not so long as in ponytail) can help keep the bugs at bay, too, when DEET treated and shaken in their clouds.

Edited by romandial on 02/20/2010 16:11:42 MST.

Travis Leanna
(T.L.) - MLife

Locale: Wisconsin
Re: Re: Diluting Deet? on 02/20/2010 16:16:54 MST Print View

>I killed with one hand, one swat, no smearing on my pant leg on my shin -- wait for it -- 94 mosquitoes once.

That's pretty gross Roman! With that many bugs, at least you know you'd never starve on a trip like that.....

Brad Groves
(4quietwoods) - MLife

Locale: Michigan
Re: DEET on 02/20/2010 16:34:05 MST Print View

It struck me that Icaridin had to be the same as Picaridin, and as it turns out, they are. Some info from Wiki:
"Icaridin has been reported to be as effective as DEET without the irritation associated with DEET.[3] According to the WHO, icaridin “demonstrates excellent repellent properties comparable to, and often superior to, those of the standard DEET.” In the United States, the Centers for Disease Control and Prevention recommends using repellants based on icaridin, DEET, or oil of lemon eucalyptus (which may require more applications.

Unlike DEET, icaridin does not dissolve plastics.[5]

Picaridin, first used in Europe in 2001, has been reported to be effective by Consumer Reports (7% solution)[6] and the Australian Army (20% solution).[7] Consumer Reports retests in 2006 gave as result that a 15% solution was good for about one hour against Aedes and 4.8 hours against Culex."

I use DEET, but I minimize my use of it. Seriously, if it destroys other materials, can it somehow be totally safe on your skin? I mostly apply it to clothing, and suffer through the extra heat of long shirt and pants when the bugs are bad... just keep the extra barrier for bite protection for the critters that aren't overly deterred by the DEET.

I'd like to point out that back in the day, DDT (not DEET), was said to have proven completely safe for wide-spread use on humans. They actually drover tanker trucks down city streets spraying people and property... went to city pools and sprayed everybody (I've seen video of this happening). Then they found out about all the hormonal effects, the massive effects on life cycles, the huge die-offs in some animal populations... a little book called "Silent Spring" came out. So no, I don't totally trust the findings of regulators in ruling a substance completely safe/harmless/whatever in low doses. They said DDT was as good for you as broccoli, after all ;P I guess it's like most things: Moderation in all things, including moderation.

Travis Leanna
(T.L.) - MLife

Locale: Wisconsin
Re: Re: DEET on 02/20/2010 16:40:39 MST Print View

I took a bottle of Picaridin to Michigan's U.P. last summer. The mosquitoes were horrible. I would get bites on my hands while walking with trekking poles briskly down the trail. Picaridin worked very well, but it seemed to wear off faster than DEET.

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: Diluting Deet? on 02/20/2010 16:43:46 MST Print View

Roman wrote, "On that trip my 2 ounces of 100% DEET ran out in about 5 days....midway through the trip.".

Was that used on a group or just you? DEET directions call for just 4-6 drops per application -- and I believe twice per day. If you applied 2 entire ounces on yourself in just five days, then I can see why you found it "numbing" and "nasty"! And I can also see why it still remained ineffective.

DEET is supposed to mask you -- as if you weren't there. It does NOT repel or kill skeeters! If the swarms were as thick as you described -- then they were simply EVERYWHERE -- whether they detected you or not. Something that thick, "cloaking" wouldn't be enough -- one would need netting and proper clothing -- physical barriers!

Edited by ben2world on 02/20/2010 18:37:52 MST.

Dean F.
(acrosome) - MLife

Locale: Back in the Front Range
DEET & DDT on 02/20/2010 17:42:16 MST Print View


"So no, I don't totally trust the findings of regulators in ruling a substance completely safe/harmless/whatever in low doses."

No doubt- as I said, "as best we know". But it only took us, what, 20 years of heavy use to figure out what DDT does? We've been using DEET for over three times that. And DDT is simply a different animal than DEET, anyway. I want to see those DEET/carcinogen studies you mentioned, because I've never found anything similar that looked like anything other than scaremongering.

And, as an aside, I'd point out that the WHO and other healthcare NGOs still strongly support the use of DDT in certain circumstances because it is such a frustratingly good (and cheap) insecticide. When used in responsible fashion for mosquito control in many third world countries the benefits greatly outweigh the risks. So, as I mentioned above, DEET is indeed toxic, but risks are probably lower than diseases caused by insect vectors. Not to mention they are simply annoying as hell. So, absolutely, know that DEET has problems- but don't fear it irrationally. I guess that's all I'm saying.

After all, ALL substances are toxic- the only issue is dose...


No one really knows how DEET works. But the pendulum is currently swinging to the opinion that the old "DEET makes you invisible to bugs" model isn't quite correct, and that it probably DOES have repellent properties. But who really knows, eh? Permethrin OTOH we know kills bugs dead.

Edited by acrosome on 02/20/2010 18:35:47 MST.

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: DEET & DDT & Whatever Else... on 02/20/2010 18:19:02 MST Print View


Not an expert at all, but if DEET repels mosquitoes potently, then that should be detectable. Methinks DEET probably has some repelling properties -- but they aren't the main forces at work. Hence, more doesn't work better -- not significantly anyway.

Actually, my interest is not so much in 100% DEET or 30% Deet. What I am after is another ingredient that I can mix in with my 3M Ultrathon -- to repel biting flies! Any ideas?

Sorry for repeated tangents but I imagine Konrad might be interested in something that "cloaks" (or repels) mosquitoes like DEET as well as something else that can protect him from biting flies as well??

Edited by ben2world on 02/20/2010 18:42:02 MST.

Konrad .
(Konrad1013) - MLife
no worries on 02/20/2010 19:02:02 MST Print View

Yeah, all this info is very helpful, so run with it in any direction as you may.

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: Options on 02/20/2010 19:20:56 MST Print View


How are you liking lemon eucalyptus? Very effective or not really? Picaridin was mentioned up above. No direct experience, but have heard lots of good things about it -- esp. from European hikers. Wonder if Picaridin will repel black / biting flies?

Edited by ben2world on 02/20/2010 19:21:37 MST.

Dean F.
(acrosome) - MLife

Locale: Back in the Front Range
Re: Re: DEET & DDT & Whatever Else... on 02/20/2010 19:40:01 MST Print View

Utterly guessing here, but from DEET's chemical structure (it's been a while, but it looks like a methylated benzoic acid with the -OH group replaced with a simple tertiary amine- whatever the hell THAT would be called) it looks like it would do best in solvents like benzene or other hydrocarbons, but I suspect that water would work, though alcohol would be better. (Heck, somebody just look at the ingredients of their <100% DEET cream and see what it's cut with.) Anyway, it doesn't look RIDICULOUSLY lipophilic- if nothing else IIRC the amine group should help with water solubility. But eucalyptus "oil"- if it is indeed an oil- might make a better solvent. But you never know if there will be some odd reaction between the DEET and a component of the oil, so I don't recommend experimentation.

But I'm an amateur going by my imperfect recollection of college O-chem, and IIRC someone here on BPL is a chemist. When you're talking about mixing complex chemicals like these I'd defer to the experts. So, any ACS members out there?

Edited by acrosome on 02/20/2010 19:46:49 MST.