> The hair at the site of the mark will grow back white and show the identification number
Is freezing a follicle turning the hair permanently white? I couldn't find anything on the mechanism. I'm surprised that people who are into body art (tattoos, piercings, etc.) didn't pick something like this up.
In that case (fascinating reading!), the person used far too cold of a solution, applied it for too long, and in consequence suffered a really bad injury, possibly compounded because she didn't seek treatment for 2 and a half weeks. Also, it was on a forearm, not the head or other hairy areas, so the mechanism of marking was more "kill the whole skin" than "kill pigment cells" specifically.
It could be done in a much safer manner - I don't think it really proves much about effectiveness overall.
Is freezing a follicle turning the hair permanently white? I couldn't find anything on the mechanism. I'm surprised that people who are into body art (tattoos, piercings, etc.) didn't pick something like this up.