A hair dresser I went to years ago switched to working out of her home instead of a salon because she said she was concerned about formaldehyde exposure. She told me Brazilian blowouts and other treatments and dyes have heaps of formaldehyde.
One reason for the prevalence of all kinds of eco/hippie/etc hair salons is that many hairdressers develop allergies against all the chemicals they're working with.
That reminds me of hearing about the problems that Aardman Animations (Wallace and Gromit films amongst others) had with getting/keeping plasticine artists - after a while they develop an allergic reaction to plasticine.
