Kathy:  The issue of hair coloring has been discussed before.  You might
check the archives, but I don't recall any references being cited.  I'm
getting a little tired of saying this, but why do you have to supply
references to say that it's safe?  Why don't those docs who are saying
"NO" so emphatically have to provide their data which back up their
assertion that this is harmful?  There must be case reports of babies that
turned purple when their mothers dyed their hair purple, right ;) ?  I
don't want to be facetious, and we do need to consider potential risks of
substances in mother's milk, but these docs need a copy of the documented
risks of artificial feeding for some perspective against the slight, if
any, risk of a small amount of material being absorbed from mother's
scalp, a tiny fraction of which may or may not get into the milk, a small
fraction of which may or may not be absorbed by the baby's GI tract, etc.
Hope this helps, Alicia Dermer, MD, IBCLC.