What some seem to be forgetting is that permethrin is used at many different concentrations. The concentration that is used for head lice and scabies the common prescription is Permethrin with 5% concentration for scabies, and OTC (over-the-counter) treatment for head lice/crabs is usually permethrin with 1% concentration.
The Active Ingredient in Sawyer brand is Permethrin at a 0.5% concentration, anyone see the difference here? How can this be??????? The concentration is so much higher in the prescription and OTC "SKIN" treatments than that which is used for outdoor clothing such as the Sawyer brand.
Also one thing that has not been said is the largest use of permethrin is the agricultural department. It is sprayed over crops, fields, to kill livestock parasites and for industrial/domestic insect control with million of gallons sold each year for this primary use. The testing that was done was with this concentration, and was done with a product in "Liquid" form.
It should also be remembered that when the product has had the proper time to dry the chemical bonds to the fabric, and is inert. It cannot be re-constituted by water, sweat, or absorbed into the skin. The only reason that it lasts approx 6 washings (or whatever the allotted time frame) is the agitation from a washing machine along with detergents break the bond which slowly removes the application from the garment.
There also seems to be a good bit of copying and pasting from other sites but leaving out some vital information, here are a few tidbits
-According to the Connecticut Department of Public Health, permethrin "has low mammalian toxicity, is poorly absorbed through the skin and is rapidly inactivated by the body. Skin reactions have been uncommon."
This was taken from the wikipedia site here- http://en.wikipedia.org/wiki/Permethrin
And- However a more recent 2007 study by the same researcher concluded that there was "little hazard to humans"
This was taken from the same site as the above.
One could copy and paste to make it say anything that they want, best thing to do is read it for yourself.
As has always been said everyone should make their own determination as to what they use and how they use it, as its your health and safety and no one else's (unless you are responsible for others). Being properly informed is the best way to make sure you are doing the right thing, so always read the labels, do the research, and you always have the opportunity to email the company and or manufacturer for further clarification.