Maybe the concentration has to be high enough that this wouldn't happen often in practice? The point made below about mice having thinner skin makes sense too,

Maybe the concentration has to be high enough that this wouldn't happen often in practice? The point made below about mice having thinner skin makes sense too, though there are parts of the body where skin is quite thin, like ears and wrists. I have a feeling that this will get tested by some intrepid YouTuber before the authors of the paper get approval from an ethics review board. I'll try to remember to Google this in a month or two.