Leviticus 22:4-5

4None of the offspring of Aaron who has a leprous disease or a discharge may eat of the holy things until he is clean. Whoever touches anything that is unclean through contact with the dead or a man who has had an emission of semen,

5and whoever touches a swarming thing by which he may be made unclean or a person from whom he may take uncleanness, whatever his uncleanness may be—