Мишна́ к Брахо́т 1:6

There are ten [grades of] impurity that emanate from a person:A person before the offering of his obligatory sacrifices is forbidden to eat holy things but permitted to eat terumah and [second] tithe. If he is a tevul yom he is forbidden to eat holy things and terumah but permitted to eat [second] tithe. If he emitted semen he is forbidden to eat any of the three. If he had intercourse with a menstruant he defiles the bottom [bedding] upon which he lies as he does the top [bedding]. If he is a zav who has seen two discharges he conveys impurity to that on which he lies or sits and is required to undergo immersion in running water, but he is exempt from the sacrifice. If he saw three discharges he must bring the sacrifice. If he is a metzora that was only enclosed he conveys impurity by entry [into an ohel] but is exempt from loosening his hair, from rending his clothes, from shaving and from the birds offering. But if he was a confirmed metzora, he is liable for all these. If a limb on which there was not the proper quantity of flesh was severed from a person, it conveys impurity by contact and by carriage but not by ohel. But if it has the proper quantity of flesh it conveys impurity by contact, by carriage and by ohel. A "proper quantity of flesh" is such as is capable of healing. Rabbi Judah says: if in one place it has flesh sufficient to surround it with [the thickness of] a thread of the woof it is capable of healing.

Negaim may not be inspected in the early morning or in the evening, nor in a house, nor on a cloudy day, because then the dull white appears like bright white; nor may they be inspected at noon, because then the bright white appears like dull white. When are they to be inspected? During the third, fourth, fifth, eighth or ninth hour, the words of Rabbi Meir. Rabbi Judah ruled: during the fourth, fifth, eighth or ninth hour.

The following disqualify terumah:One who eats foods with first degree uncleanness; Or one who eats food with second degree uncleanness; And who drinks unclean liquids. And the one who has immersed his head and the greater part of him in drawn water; And a clean person upon whose head and greater part of him there fell three logs of drawn water; And a scroll [of Holy Scriptures], And [unwashed] hands; And one that has had immersion that same day; And foods and vessels which have become defiled by liquids.