Charles Ellicott Commentary Ezra 2:62

"These sought their register [among] those that were reckoned by genealogy, but they were not found: therefore were they deemed polluted and put from the priesthood." — Ezra 2:62 (ASV)

Their register among those who were counted by genealogy. —Better, their record, or the record of the Registered.

Polluted. —Levitically disqualified.