Don't worry about using chemical dyes. I've tried henna before and you know what? It didn't change the colour of my hair atall. I was really irritated that after 4 hours of having stuff that smelt so rank on my head I still had the exact same colour.

I'm sure there are lots of dyes that don't have PPD. I just wouldn't know which. Personally I use Loreal dye mostly... I use their Couleur Experte dye because I like having highlights rather than flat colour. Really I don't see the big deal about damage, my hair is fine with chemical dye. Bleach on the other hand... not so much