The title of this thread is not accurate. There is no demonstrative danger when Permethrin is used at the dosages recommended. Nor does the quoted article describe such a risk with normal consumer use. In fact, I found it curious that the most important part of the article was left out. The deleted portion underscores what I wrote above about consumer use. Here is the missing part of the article:
CONCLUSIONS
Permethrin is neurotoxic
in animals at high doses. The neurotoxic symptoms
of pyrethroid toxicity in humans appear to mimic those observed in animals. The estimated NOEL for neurotoxicity in rats by dermal route is 200 mg/kg (Robinson, 1989a). In the committee's judgment, 125 mg/kg is the LOAEL for permethrin from oral exposure in rats (Glaister et al., 1977; ICI, 1984).
Based on a NOAEL of 200 mg/kg per day from the available neuro toxicity data, the margin of safety (MOS) associated with daily human exposure to permethrin from permethrin-treated BDUs at a level of 6.8 × 10 −5 mg/kg per day is approximately 3 million.
Because the daily lifetime dose for garment workers (3 × 10 −5 mg/kg per day) is less than the daily dose for military personnel, the MOS for garment workers is even higher—6.8 million.
Therefore, neurotoxicity that could result from wearing permethrin-impregnated BDUs or working with treated fabric should not be a concern.
I added the bold effect and increased the text size as emphasis.
As a person who has worked in Public Health evaluating scientific literature, it is important that if research is used to support a point of view, that it actually be relevant to that specific issue.
Using Permethrin as a repellent against bedbugs is useless; bedbugs are not repelled by it. If one is using it to kill any critters that stow away in a backpack, then it could be effective as an insecticide.