There was a reference a while back to children developing peanut allergies
after their mothers used peanut oil as a massage oil on their breasts.

Last year, while I was battling a skin problem around my eyes, I used
lanolin several different times.  I'd put it around my eyes at bedtime.  In
the morning, I'd have an oily film over my vision that took a while to
clear.  No lanolin, no film.

My  guess was that as it warmed it "crept" across my skin in small
quantities, ending up in places I hadn't put it.  I imagine any lotion that
we use on our breasts could have the potential to "creep" beyond where we
use it - possibly to our areolae and thus to our babies.

Diane Wiessinger, MS, IBCLC, LLLL  Ithaca, NY