Some of those items on the list are sending up red flags to me. The weapon use is purely because it heats skin; if you apply a million times less energy for a million times as long, the danger level from heat is zero. When it can't penetrate skin, it does make sense to classify head skin exposure the same as foot skin exposure.

The thing about sweat glands is interesting. And sadly I have no idea how to evaluate the quality of the studies linked.