Hi, My GP told me that unless you are dying your hair every day, the chemicals that would come through to bubs are trace amounts, if any at all. He did say to try and stay in awell ventilated area to make it even safer- I always did mine at home, then sat outside till it set.
With all the other chemicals and pollution we are exposed to every day, I don't think a hair dye will hurt- and it will make you feel like a million bucks