Leviticus 22:3-5

³Tell them: These rules apply for all future generations. If any of your descendants in an unclean state comes close to the holy offerings that the Israelites dedicate to honor the Lord, that person must be expelled from my presence. I am the Lord.

⁴If one of Aaron's descendants has a skin disease or a discharge, he is not allowed to eat the holy offerings until he is clean. Anyone who touches anything made unclean by a dead body or by a man who has had a release of semen,

⁵or anyone who touches an unclean animal or an unclean person, (whatever the uncleanness is),