I don't know for sure about the Breastmilk but you could sure test positive
in your urine.  But one of the things that is suppose to happen if there is
a positive result from a legal drug screen (as opposed to a medical drug
screen) is that a MRO Medical Review Officer is suppose to speak with the
patient with the suspected positive test and determine if there is any
legitimate reason why the test turned positive. For example perhaps the
person was taking Tylenol with Codeine from a dentist for  dental pain.  Or
they had recent ingested poppy seeds in some food.

My question is why would you want to do a drug screen on the breastmilk
anyway.  If you are looking for drugs of abuse, urine is a much better
substance to use.  If you were concerned about the effect of a drug it
would make more sense to check the serum levels in the infant.  But since
this question involves poppy seeds and BM levels I am a bit curious just
what the circumstance is.

Jon Ahrendsen MD FAAFP
LLLI Medical Associate
and Medical Review Officer