In Jane Zukin's book "Raising Your Child Without Milk", she cites
a study that claimed that RAST was quite unreliable for milk-protein
allergies, although quite good for other allergies.  I don't know if that has
changed or not.

By the way, Jane has a very interesting section on some studies done
on colicky babies and a specific cows milk protein (an antibody, IgG)
that seems related to colic.  It goes through the gut and into breastmilk
quite readily and was found to be in concentrations 200 times higher than
other cow's milk proteins that get into human breastmilk.

Kathleen