Permethrin Dilution

[AO2134]

I tried to use a search of permethrin and it didn't turn up anything on my search. Hopefully, this isn't a repeat (but I got a feeling it likely is).

I plan to purchase Permethrin SFR Insecticide 36.8 % at http://store.doyourownpestcontrol.com/permethrin-sfr-insecticide-qt

Previously, I purchased the sawyer permethrin from REI at $16 a bottle. Then I thought to myself, I am not too stupid too function, I should be able to dilute this myself. Mind you I suck at math, science, and life in general.

So I googled a formula for dilution of solutions. I found C1V1=C2V2, where C1 is % of solution (36.8%), V1 is the volume of C1, C2 is % of final solution, and V2 is volume of final solution.

I noticed that the sawyer permethrin I was purchasing had .5% permethrin. So I had a final % goal.

I saw a video from Chad P where he combined 2 oz of permethrin with 1 gallon of water.

1 gallon = 128 oz.

With that, I was ready to go:

C1V1=C2V2.

36.8%*2 oz = C2*130 oz (130 because 128 oz plus original 2 oz of permethrin).

Then you isolate C2 by dividing 130 oz from both sides leaving:

36.8%*2 oz/130 oz = C2. Cancel out the ozs to get:

36.8%/65 = C2

0.566% = C2.

So the final solution is a little high by the .5% standard set by sawyer permethrin at REI. So the online video was comfortable with this.

So, then I looked at the formula again. Since I know what my final solution % was to be, I decided to go a different route.

C1V1=C2V2

36.8%* 2 oz = .5%*V2. Solve for V2. This time, I am solving for my final volume.

36.8 %*2 oz / .5 % =V2.

147.2 oz = V2.

So, you would need 145.2 oz of water to the 2 oz of 36.8 % permethrin.

IF my math and common sense (or lack thereof) is wrong, please let me know.

WARNING: I likely am too stupid to function. You follow this advice at your own risk. I suck at math. I suck at science. I have never mixed chemicals. I am not saying 0.5% is safe. I am just basing it off of what the Sawyer bottle from REI says. You assume your own risk by following any advice given by this idiot.

[rhjanes]

Sticks Blog, might be what you want
CLICK THIS (http://sticksblog.com/2012/05/05/dealing-with-ticks/)

[Fireonwindcsr]

I purchased a 32oz bottle of the tick killer on Amazon and poured it into 4oz bottles.

http://www.amazon.com/Sawyer-Products-Permethrin-Clothing-Repellent/dp/B001ANQVZE/ref=sr_1_1?s=lawn-garden&ie=UTF8&qid=1425944281&sr=1-1

[iAmKrzys]

Sticks Blog, might be what you want
CLICK THIS (http://sticksblog.com/2012/05/05/dealing-with-ticks/)

I always hated breathing in permethrin while spraying (even if it is supposed to be safe) so I bough myself a respirator mask with filters just for these fine application moments. Hence the prospect of soaking my clothes in a bucket sounds really exciting. Yet I noticed that the color of the concentrated solution is different from what's in Sawyer's bottles, so I wonder if Sawyer adds anything extra that prevents permethrin from wearing off too quickly. After all, it would be a pity if a good downpour washed off all my tick protection.

[Walkintom]

I've gotten pretty dosed with various insecticides when applying them over the years and unless you have a particular sensitivity or allergy we can usually take a LOT more than an insect with no ill effects.

Permethrin is considered safe for infants at 5% concentration lotion applied directly to the skin for scabies.

I wouldn't advise making permethrin koolaid, but you're likely to come out just fine with your experiment. Less dangerous than cigarettes is my opinion on what you're discussing.

Just check the other ingredients to be sure none of them are skin irritant at the diluted concentration you intend to use.

[AO2134]

So I just talked to a really good friend who is the smartest person I know and a pharmacists. He politely called this treatment program "f*****g idiotic."

The danger of permethrin is not its contact with our skin but when it is inhaled. So the initial mixing is a big risk to humans. Once dry, of course, he agreed permethrin is harmless, but that is solely if the treated clothes STAY dry. The idea that the chemical "deactivates" or is rendered "harmless" once dry is partially true and mostly fallacy. So long as the treated clothing stays completely dry, it is harmless. True. The threat of permethrin isn't it being absorbed into our skin, but inhaled by our lungs.

So what happens when you sweat? Your shirt gets wet. What happens when you stop sweating? The shirt begins to dry. How does that happen? The water dissipates into the air. Guess what comes along with it? The permethrin. In what form does it come in at this stage? It's most harmful form to humans: air inhalation.

The idea that a chemical somehow changes or becomes inactive once dry, he says, is pure fallacy. That chemicals don't work that way. Especially pesticides.

His best quote was "which is kinda ironic cause you're using a neurotoxin to prevent getting a disease that... acts like a neurotoxin lol"

I ended the conversation after I told him he was depressing the crap out of me.

[Walkintom]

So I just talked to a really good friend who is the smartest person I know and a pharmacists. He politely called this treatment program "f*****g idiotic."

The danger of permethrin is not its contact with our skin but when it is inhaled. So the initial mixing is a big risk to humans. Once dry, of course, he agreed permethrin is harmless, but that is solely if the treated clothes STAY dry. The idea that the chemical "deactivates" or is rendered "harmless" once dry is partially true and mostly fallacy. So long as the treated clothing stays completely dry, it is harmless. True. The threat of permethrin isn't it being absorbed into our skin, but inhaled by our lungs.

So what happens when you sweat? Your shirt gets wet. What happens when you stop sweating? The shirt begins to dry. How does that happen? The water dissipates into the air. Guess what comes along with it? The permethrin. In what form does it come in at this stage? It's most harmful form to humans: air inhalation.

The idea that a chemical somehow changes or becomes inactive once dry, he says, is pure fallacy. That chemicals don't work that way. Especially pesticides.

His best quote was "which is kinda ironic cause you're using a neurotoxin to prevent getting a disease that... acts like a neurotoxin lol"

I ended the conversation after I told him he was depressing the crap out of me.

So, just to get this straight - Permethrin is dangerous when applied to clothes that eventually get wet?

I'm gonna throw the BS flag here. Your friend may be smart but I don't think he is correct.

By that statement, none of the treated clothing you can buy would be safe, nor any of the aftermarket treatments.

Not that I suggest deliberately concentrating and inhaling it, but seriously - the dried permethrin gets wet from sweat and somehow creates a dense enough fog of toxicity to harm you - I don't buy it one bit. You'd have to have a LOT of it to do that. Way more than you could concentrate on your clothing in the first place. When you're hiking, you're outdoors - constant air exchange.

[Odd Man Out]

You did a very good job of sorting this out and the answer you came up with is almost certainly close enough (closer than the original figure you got from the video). I doubt it is necessary to get the concentration to be EXACTLY 0.5% However, we can do a little better if you would like.

Warning: Chemistry ahead. If you want the easy answer, go to the last paragraph.

The formula you used (C1V1=C2V2) works only for volume based concentration units (amount of permethrin per volume of solution). But the 36.8% unit give is a mass based concentration unit (36.8 g of permethrin per 100 g of solution). For dilute solutions the difference is negligible. But for concentrated solutions, the difference is noticible. There are couple of ways to proceed.

One is to do the measurements based on mass. The calculations are pretty easy since you are using mass based units. Suppose you were to measure out 50 grams of the concentrate. 36.8% of this is permethrin (18.4 g of permethrin). Divide 18.4 g by 0.005 (i.e. the decimal form of 0.5%) you get 3680 g which is the total mass of the final solution. Since you started with 50 grams, you have to add 3630 more grams of water to get the correct final solution. Here you can take advantage of the fact that the density of water is 1 g/mL so 3630 g of water is 3630 mL or 3.63 L or 123 oz of water. So the recipe is 50 grams of concentrate plus 123 oz of water gives you a 0.5% solution.

But many people would rather measure volumes than mass. Another way to proceed is to convert the volume to mass and then proceed as above. This can be done with the density of the solution, which is provided on the product label as 3.2 lbs/gal

http://www.doyourownpestcontrol.com/SPEC/LABELS/PermethrinSFR_Label.pdf

A density of 3.2 lbs/gal converts to 1042 g/L. So lets calculate the recipe for starting with 2 oz of concentrate (as in your original recipe). This is 0.05915 L. Using the density this converts to 61.64 grams of solution. 36.8% of this is permethrin or 22.68 g of permethrin. Divide by 0.005 to get the total mass (4537 g) to give you a 0.5% solution. Subtracting the 61.64 g you started with, you need to add 4475 g of water or 4.475 L which is 151.3 oz of water to add to 2 oz to get a 0.5% solution. This is only 6.1 oz more than your value, showing that the more rigorous calculation is only a slight improvement). Using your original recipe, you come up with a 0.521% solution.

Now there is an easier way to do this. You can use the density of the concentrate to calculate a percent concentration by volume (%w/v) of 38.35%. Then you can use your C1V1=C2V2 formula and get the right answer. Now if you just repeat your calculation with C1=38.35%, C2=0.5%, and V1=2 oz. Solve for V2 and you get 153.4 oz. Subtracting the 2 original oz you get the recipe of 151.4 oz of water to add to 2 oz (about the same as above). There are two very slight errors in this calculation. This assumes the density of the final solution is 1 g/mL and it assumes 151.4 oz of water and 2 oz of concentrate gives153.4 oz of solution. Neither are exactly correct, but the error is so small it doesn't really matter.

[Odd Man Out]

P.S. In case you were wondering, I am a Biochemistry Professor, so the solution calculations are pretty straight forward for me. I hope you found that more useful than the pharmacist's advice. BTW, I agree with Walkintom - the technical literature on permethrin is less scary than the pharmacist would lead you to believe.

[squeezebox]

If the companies that sell treated clothing are anywhere close to being right about the permethrin lasting for 70 washings (with soap) getting soaked with rain should not be much of an issue. I'm not a pro just thinking.
I will add a dust mask to the chemical gloves and do the whole process outside.

[Rocket Jones]

Absolutely wear gloves while treating your clothes. I don't wear any kind of respirator, but I do the work outside with plenty of fresh air.

I also lay my clothes flat to dry instead of hanging them. I figure that way the strength of the treatment will be more even than if the liquid drips from the line. I've heard that sunlight can degrade permethrin too, so I wait for an overcast day. Maybe it doesn't matter much, but it couldn't hurt.

As for the effectiveness, I once sat in the middle of a cloud of insects, including several wasps, and not one landed on me.

[AO2134]

Not trying to be argumentative. I promise.

But first Odd Man Out. Thanks! That is very helpful. I had to read it twice, but I think I got it. Thank you sir.

I think the point is that the idea that permethrin is rendered "harmless or unactivated" after the clothes dry is incorrect. Long term, constant exposure to permethrin is unstudied. Studies suggest you need high exposure amounts for humans. How much exposure to constant permethrin is dangerous? We don't know. So there are no studying directly on point.

Permethrin is a neurotoxin. It has a cumulative affect. Although the body does eliminate it via liver, the process takes time. Constant exposure to it will allow an unhealthy build up. (i.e., if I eliminate 5 ml but I add 6 ml, at some point, I am in trouble). It appears no one really knows how much we can take. We know it is virtually harmless in our skin, but in our lungs it is very dangerous.

The worst part of neurotoxins appear to be that they may not give symptoms for many years. We could be damaging ourselves and not even knowing it.

Just an example, many years ago, society thought smoking was harmless. Now we know better.

Maybe this is another example of a "smoking" situation. Maybe it isn't. I don't think we really know. I definitely wanted to correct this perception that is "completely harmless" once dry. It is not. It may not be enough exposure to be harmful, but without question is it some exposure to something that could do debilitating damage to our nervous system.

Finally, we are in open air. That without a doubt helps dissipate something that is already dissipated and a low concentration, but it doesn't mean there is no inhalation of the neurotoxin.

Oh and one other thing. Simply because companies sell products clothes treated with permethrin is not a persuasive argument for it's safety in my book. How many times have we seen products get pulled because we learned, after the fact, that they weren't safe? In fact, we, as a people, used to think the earth was the center of the universe. The fact that the overwhelming majority of people believe we were the center of the universe, clearly, did not make it true.

Some precautions I plan to take.

I will treat my clothes at .5%, but only my pants and socks. My shirt, which will be the most likely to sweat and dissipate and is the closest thing to my face, I will think of something else. Maybe a lower concentration. Maybe something else. Not sure. As I always bring camp clothes, I will leave my treated clothing outside my tent so it doesn't dry overnight in an enclosed environment (my tent).

Well that is my plan. It may be a useful activity, but that's the plan.

[swisscross]

I purchase some Permethrin last year to soak my clothing for a section hike.
Did a good bit of research and found a few references that on rare occurrences it can cause seizures.
Hmmm...as an epileptic I am extremely concerned. Any advice.

I might give it a go but get my wife to soak them and wash the clothes a few times before wearing them.
Also want to wear them a few times before heading out into the woods to see if I have any symptoms.

[Boo8meR]

I have a question that's somewhat related to this discussion. I have a bottle of the Sawyer Permethrin and I had planned to treat all of my clothes/gear with it. On the bottle, it says it provides 42 days of protection. I'm leaving for my thru-hike tomorrow. Would you guys go ahead and treat everything prior to leaving and then just plan on doing it again at the end of April, or would you just have someone mail it to you at the end of April since bugs aren't likely to be out during the next few weeks? I'm all ears.

[AO2134]

I have a question that's somewhat related to this discussion. I have a bottle of the Sawyer Permethrin and I had planned to treat all of my clothes/gear with it. On the bottle, it says it provides 42 days of protection. I'm leaving for my thru-hike tomorrow. Would you guys go ahead and treat everything prior to leaving and then just plan on doing it again at the end of April, or would you just have someone mail it to you at the end of April since bugs aren't likely to be out during the next few weeks? I'm all ears.

As for how safe it is, I'd see above discussion, but in terms of what I would do. It is probably safe at low concentrations, but I haven't seen a long term study one way or the other. If I wasn't worried about the chemical aspect, I would treat now. Adds no weight. Adds peace of mind. It is fairly cheap so it doesn't hurt budget much. The real significant risk of ticks with lyme disease, from what I've seen, is in the northeast.

Also, I'd advocate that LNT should adopt the no cleaning of treated clothes in or near streams, creeks, or rivers.

The PDF posted by odd man out states, "This product is extremely toxic to fish and aquatic invertebrates. Do not apply directly to water, or to areas where surface water is present or to intertidal areas below the mean high water mark. Do not contaminate water by cleaning of equipment or disposal of equipment washwaters. Do not apply when weather conditions favor drift from treated areas."

Knowing that, I wouldn't rinse my treated clothing in a creek or stream. But then again, I found it disgusting that people on the trail bathe in rivers or creeks. The do it "downstream" logic is stupid. Generally speaking, you are always upstream to someone or something.

Why not carry the water in a platypus or bottles and clean yourself off a safe distance from the water source? That is what I would do.

[Rain Man]

This is perhaps the weirdest Permethrin thread I've ever read.

Let me just say I'm glad I have an asphalt driveway, for as we've been told, once a elements of a liquid mixture react and bond, that is undone as soon as they wet again. WOW. Thank goodness my driveway's not concrete!

For those who prefer going to the horse's FRONT end, here's the link I rely on--
Sawyer video (http://vimeo.com/39012753).

[AO2134]

This is perhaps the weirdest Permethrin thread I've ever read.

Let me just say I'm glad I have an asphalt driveway, for as we've been told, once a elements of a liquid mixture react and bond, that is undone as soon as they wet again. WOW. Thank goodness my driveway's not concrete!

For those who prefer going to the horse's FRONT end, here's the link I rely on--
Sawyer video (http://vimeo.com/39012753).

So let me analyze your comment.

If the elements do not become "undone," I wonder why we have to treat clothing more than once? It should be permanent, if they do not become undone. Why a limit to 6 weeks or washes? Clearly, permethrin, unlike concrete, is less permanent.

The analogy (cement and permethrin) you make also holds no water. Pun intended.

[mbqhappy]

FYI...I was just about to post your same question in the Forum.
Apparently, you did not get answered. Did anyone followed up on your question? I am interested in learning what others commented on your question.
Eagerly awaiting your response Thks for your time.

[egilbe]

Washing clothing knocks the permethrin molecules off. Permethrin has an effective concentration and once it is bow that level, it's no longer useful. Permethrin also degrades with exposure to UV light. Sunlight destroys it, reducing it's effectiveness. It's a non-persistant insecticide. Insects have a different nervous system than mammals, so it affects bugs, but not mammals, except for cats. Our skin breaks it down. That's why permethrin is not effective being sprayed like DEET.

[Hikingjim]

So I just talked to a really good friend who is the smartest person I know and a pharmacists. He politely called this treatment program "f*****g idiotic."
The danger of permethrin is not its contact with our skin but when it is inhaled. So the initial mixing is a big risk to humans. Once dry, of course, he agreed permethrin is harmless, but that is solely if the treated clothes STAY dry. The idea that the chemical "deactivates" or is rendered "harmless" once dry is partially true and mostly fallacy. So long as the treated clothing stays completely dry, it is harmless. True. The threat of permethrin isn't it being absorbed into our skin, but inhaled by our lungs.

So what happens when you sweat? Your shirt gets wet. What happens when you stop sweating? The shirt begins to dry. How does that happen? The water dissipates into the air. Guess what comes along with it? The permethrin. In what form does it come in at this stage? It's most harmful form to humans: air inhalation.

The idea that a chemical somehow changes or becomes inactive once dry, he says, is pure fallacy. That chemicals don't work that way. Especially pesticides.

His best quote was "which is kinda ironic cause you're using a neurotoxin to prevent getting a disease that... acts like a neurotoxin lol"

I ended the conversation after I told him he was depressing the crap out of me.

I don't really consider someone talking to their "smart friend" any kind of science, especially when the person relaying the information says in their first post that they suck at science. Provide real documented and linked information please, not "it makes sense because X"

[Hikingjim]

Canadian, British and I believe US military uniforms are all treated with permethrin.
Hopefully they bring umbrellas so they don't get wet?

[greentick]

Canadian, British and I believe US military uniforms are all treated with permethrin.
Hopefully they bring umbrellas so they don't get wet?

the current ACU-OCPs are treated to 50 washes.