Leviticus 5:2

or if any person touch any unclean thing, either a corpse, or the unclean prey of wild beasts, or the carcasses of unclean abominations, or the carcasses of unclean beasts, or shall touch any impurity of man—any of his impurities by the touching of which one would be defiled, and it escaped his notice and he hath afterwards come to the knowledge of it;