My Mum had Breast Cancer, and she says No to the Chemicals due to reaction of my skin. If ya do it, just do the test behind your ear as they explain on the box. Mix just half a cm of tint and a drop of the Peroxide (white in bottle). Put onto skin behind the ear, a dab, and your supposed to leave it there for 24 hours to see if there is a reaction. This is supposed to happen before each time you have a colour (oh please). I was a hairdresser for 20 years, and I hate to say, no one ever asked for the test and we didnt do them. I wonder if theyre getting fussier now! So keen to hear how people have gone. I have sensitive skin, so I shall test first. I hate my natural dark and steely grey hair poking out. My goodness, nothing ages a female faster than a natural grey - sorry , my opinion, and having transformed women for 20 years, you can look 10 years younger by having a great colour. Golden rule is = 3 shades away from your natural. Only time this changes is when you have foil work. Red next to the skin brings out the red in your skin. Black is always harsh unless youre in your teens and then it just = rebellion. (I did that too!). I see so many women say "But I was always blonde" and go too light and it sucks the colour out of your skin. Oh and last bit of advice, we age in 7 year cycles, so dont try to be what you were 7 years ago, try to be as beautiful as you can for the person you are today! Make sense! For those who want to make a statement with their hair, I did that too, when I was in my early 20's! Just sayin........Love Bel