The Torah in Parashat Emor (22:4) commands that a Kohen who is Tameh (impure) may not partake of “Ha’kodashim” – the “sacred food,” referring to Teruma, the portion of agricultural produce which is given to a Kohen. This portion is considered sacred, and the Torah establishes that it must be eaten in a state of Tahara (purity). The Sefer Ha’hinuch explains that this command is intended to raise the people’s esteem for sacred materials. By imposing limits on who is allowed to eat hallowed food, the Torah makes it special in people’s eyes.
The Torah issues this command to everyone “Mi’zera Aharon” – “from Aharon’s offspring,” from which the Sages inferred that it applies even to females, meaning, the female members of a Kohen’s family, who partake of Teruma. They, too, are forbidden from eating Teruma in a state of Tum’a (impurity).
A Kohen who intentionally violates this command, and eats Teruma in a state of Tum’a, is liable to “Mita Bi’ydeh Shamayim” – death at the hands of G-d (as opposed to execution by Bet Din). If he was warned before transgressing, he is liable to Malkut. If he receives Malkut, then he is absolved of the punishment of “Mita Bi’ydeh Shamayim.”
The Torah here forbids eating “Kodashim” (“sacred food”), which the Sages understood as indicating that if the Teruma had become Teme’a, then the Kohen is not liable to “Mita Bi’ydeh Shamayim.” Although it is forbidden to eat this Teruma, nevertheless, since impure Teruma is not considered “Kodashim,” eating it is not included in this prohibition, and thus the violator is not liable to death.
A Kohen who is Tameh must immerse in a Mikveh and then wait until sundown (“Ha’areb Shemesh”) before he is permitted to eat Teruma.
Although the Misva of Teruma applies only in the Land of Israel, the Sages enacted that Teruma should be given to Kohanim in certain other lands, as well. Since Teruma in these regions is required only “Mi’de’rabbanan” (by force of Rabbinic enactment), it is treated less stringently than ordinary Teruma. Therefore, such Teruma may be given to a minor who has never experienced bodily secretions which bring Tum’a (such as a girl who has yet to menstruate), even if the minor is Tameh for some other reason.
There is some discussion as to whether a non-Kohen who eats Teruma in a state of Tum’a also violates this prohibition. A separate prohibition forbids non-Kohanim from eating Teruma, and the question thus arises whether a non-Kohen who is Tameh and eats Teruma violates also the prohibition against eating Teruma while impure. The Sefer Ha’hinuch writes that the prohibition against eating Teruma in a state of impurity applies “to male and female Kohanim,” implying that non-Kohanim do not violate this prohibition. This is, indeed, the conclusion of the Minhat Hinuch (282:15), that a non-Kohen who eats Teruma while impure violates the prohibition forbidding non-Kohanim from eating Teruma, but not the prohibition against eating Teruma in a state of Tum’a.
This Torah prohibition applies only in Eretz Yisrael, and when the Torah obligation of Teruma applies – meaning, when the majority of the Jewish People reside in the Land of Israel.