Whether milk of a nursing mother who is impure naturally communicates her impurity like any other liquid which pools inside her body, or whether we view milk as food, such that it would need to be touched by a separate liquid in order to render it capable of communicating impurity ["to be machshir it"]: Keritot 13a-b
Communication of impurity from the milk of a nursing mother who is a niddah: Keritot 13a-b
Communication of impurity from the milk of a nursing mother who is a zavah: Keritot 13a-b
A Sfek-Sfeika case of doubt, regarding transmission of impurity: Doubt whether a child nursed enough milk to communicate impurity, and doubt whether he consumed it in a short enough period of time for this to be considered significant consumption: Keritot 13a
Other
Special fasts for the benefit of sailors, travellers in the desert, infants, and pregnant and nursing women: Taanit 27b
Permissibility of drinking a woman's milk: Keritot 22a