What is Permethrin?
Permethrin (per-meth-rin) is virtually non-toxic to humans and no systemic effects have been reported. In EPA and FDA tests, it was uncommon to have any skin reddening, rash or other irritation. When used as a repellent, permethrin is applied to exterior clothing where it dries and bonds to the cloth fiber. This water-based formula is non-staining, odorless and has exceptional resistance to degradation by sunlight (UV), heat and water. Although permethrin is approved for skin application under certain circumstances such as head lice formulas, it is not applied to skin as a repellent. Permethrin does not bond to skin (stick) and is quickly deactivated by skin’s esterase action into inactive compounds. Because of these attributes permethrin offers no repellent benefit on skin. It is only effective when used as a clothing treatment.
- Permethrin is over 2,250 times more toxic to ticks than humans.
- Exposure risk of permethrin-treated clothing to toddlers is 27 times below the EPA’s Level of Concern (LOC).
- A 140-pound person would have no adverse health effects if exposed to 32 grams of permethrin/day. There is less than 1 gram of permethrin in an entire bottle of clothing treatment.
- Permethrin is pregnancy category B (showing no evidence of harm to fertility or fetus).
Caution: Permethrin won’t hurt humans or dogs but it is harmful to bees, fish, and aquatic insects – do not spray clothing near flowers or water sources. Do not allow cats near permethrin-treated clothing until it has fully dried.
How to use Permethrin Spray
Now that we know what Permethrin is and that it is generally accepted that it is safe for all ages, and pregnant mothers, let’s talk about using it!
The recommended level of permethrin to use on clothing and gear is 0.5% this will kill ticks on contact. You can buy Permethrin in the sporting goods section of most big box retailers. The common Brand is Sawyer. A 24oz bottle will cost around $16 and will be enough to treat 3-6 items. I’m going to save you a bunch of money, and teach you how to make a gallon for under $10!
Head to your local Tractor Supply Company or other local farm retailer and look for a 10% Permethrin that farmers use to treat livestock.
You will find an 8oz bottle for under $10. While you’re there, pick up a large spray bottle.
If you have cats at home, you will want to make sure they are inside for the duration of the treatment process. Permethrin is fatal to cats until it is dry so keep the little fur balls safe by keeping them inside.
Since the permethrin at TSC is 10% and the recommended safe level for treating gear and clothing is 0.5% you will need to dilute it down. This is easy, fear not! First don a pair of disposable gloves, as you want to protect yourself from the “full strength” stuff. The bottle will have a handy measuring cap right on it. Measure out 1.5oz of permethrin and add it to your empty spray bottle, then fill the bottle with 28.5oz of water. Give it a shake. It will appear a brown milky color. This is because it makes a suspension when mixed with water, which means you can see that the permethrin is mixed with the water and will not separate. You are now ready to spray or soak your gear.
There are two ways to treat your gear, either by spraying or soaking. Spraying is just as it sounds and my preferred method. Line up your gear and spray it so it’s thoroughly soaked and allow to air dry. Second method is soaking which you put your gear in ziplock baggies or tubs and soak with the solution and then line dry. I find this way wastes more permethrin and is more work, but is another option. This would be a good way to treat a large amount of gear as you could put it all in a tub, add the full 8oz of 10% permethrin and add in a gallon of water.
So once you get all your gear thoroughly soaked in the permethrin allow it to air dry for 2-4 hours (or overnight if possible and living with cats). This process is best done on a hot sunny day without any wind or humidity. Once dry it will last about 6 weeks unwashed (so tents, backpacks and the like) and 4-6 washings for clothing. After that period has passed, reapply your permethrin to ensure it is well treated and doing its job.
One other thing to note is that permethrin is a contact based repellant/insecticide, this means that it will not repel ticks, mosquitoes and blackflies and other insects like typical bug sprays. So you might see a tick crawling up your treated pant leg, but know that, that tick will soon be dead before it has a chance to bite. It won’t stop the mosquitoes from buzzing in your ear but it they land on treated clothing they will die. Look into other sprays to keep annoying bugs at a distance.
TickEncounter Resource Center. Web. 22 May 2017.
“Tickinfo.com.” Repellents. Web. 22 May 2017.