These two verses make frequent use of the third-person pronoun. This makes it somewhat difficult to determine who is being spoken of at specific points. At the very least, it appears that safeguarding the holy food is the responsibility of the priesthood. If they are not careful and allow a lay person to eat of the holy food, they are responsible for bringing guilt and punishment on Israel.
15 They shall not profane the holy things of the people of Israel, which they contribute to the LORD,