Because of hearing so much about bed bugs in the albergues, in 2013 I chose to buy a sheet that I am comfortable using when I stay in albergues; it's called the InsectShield Silk Liner. There have been ample studies about the safe use of permethrin on clothing. On the https://www.epa.gov/insect-repellents/repellent-treated-clothing site there is plenty information on the use of permethrin.
Ultreïa!
I think it is important to distinguish between insects which are repelled by insect repellents and permethrin, vs the action of Permethrin as an insecticide. Given this thread, hopefully your post can be used to help with clarifying a few things.
The InsectShield link does not state what the effective ingredient is in their product, but given that it claims an effectiveness rate for up to 70 washings, it is likely Permethrin. The fact that the manufacturer claims that it is safe at all ages also supports that supposition. Also, it limits its claims of repellency effectiveness to only mosquitoes, fleas, and ticks, but does not include bedbugs, which also suggests, along with the other claims, that the ingredient is Permethrin and not DEET.
[Edit --- In another location on their website, Insect Shield does state that they use Permethrin for their products.]
As an aside, the website states that rather than silk, the product is 100% cotton and weighs just shy of 1 pound / 454 grams.
That is an important distinction, because while Permethrin will kill bedbugs, it does not repel them or keep them from biting, like it does for ticks or fleas -- although for ticks and fleas Permethrin is still not as effective as DEET. The killing action of Permethrin in bedbugs is not instantaneous. So, while it can be effective for bedbug control by an albergue or other lodging, for a pilgrim sleeping it will not kill a bedbug rapidly enough to keep the critter from its blood meal.
Before I retired from our local public health district, one of my fun (sarcasm) jobs was helping folks deal with things such as head lice and infrequently, bedbugs. Developing written protocols based on the most recent research, which would periodically change, was something I would do in order to give as handouts.
There is a saying that can help us all to understand a bit more why bedbugs bite some using certain 'treatments', while others seem to stay free from bedbug interactions using those same treatments, which includes Permethrin. "Correlation does NOT equal causation". Nor does correlation equal effectiveness.
While it is known scientifically that Permethrin does not act as a repellent for bedbugs, there are numerous anecdotal claims made by Camino walkers who say Permethrin was used and no bedbugs were encountered. This ignores the fact that far more folks, while NOT using Permethrin do not encounter bedbugs. So the most likely explanation to the seeming correlation of no bedbugs while using Permethrin is that there would have been no bedbug encounter anyway without the Permethrin.
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his NCBI published study's abstract helps to underscore the above. One would need to subscribe to Medline in order to be able to access and read the full study.
I do not recommend folks use DEET, although it will repel bedbugs. I use DEET while backpacking with heavy mosquito swarms, but not under other circumstances. DEET is of limited durability, it can hurt eyes and mucous membranes with accidental contact, and can damage some synthetic materials. If it is to be used, it is best applied to clothing, and needs to be replenished every 6 to 12 hours.
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dryer that does the trick.
