they are unclean

Leviticus 5:2
Or if a person touches anything unclean--whether the carcass of an unclean wild animal or livestock or crawling creature--even if he is unaware of it, he is unclean and guilty.

Isaiah 52:11
Depart, depart, go out from there! Touch no unclean thing; come out from it, purify yourselves, you who carry the vessels of the LORD.

Hosea 9:3
They will not remain in the land of the LORD; Ephraim will return to Egypt and eat unclean food in Assyria.

Matthew 15:11, 20
A man is not defiled by what enters his mouth, but by what comes out of it." . . .

Mark 7:2, 15, 18
and they saw some of His disciples eating with hands that were defiled--that is, unwashed. . . .

Acts 10:10-15
He became hungry and wanted something to eat, but while the meal was being prepared, he fell into a trance. . . .

Acts 10:28
He said to them, "You know how unlawful it is for a Jew to associate with a foreigner or visit him. But God has shown me that I should not call any man impure or unclean.

Acts 15:29
You must abstain from food sacrificed to idols, from blood, from the meat of strangled animals, and from sexual immorality. You will do well to avoid these things. Farewell."

Romans 14:14-17, 21
I am convinced and fully persuaded in the Lord Jesus that nothing is unclean in itself. But if anyone regards something as unclean, then for him it is unclean. . . .

1 Corinthians 8:8
But food does not bring us closer to God: We are no worse if we do not eat, and no better if we do.

2 Corinthians 6:17
"Therefore come out from among them and be separate, says the Lord. Touch no unclean thing, and I will receive you."

Ephesians 5:7, 11
Therefore do not be partakers with them. . . .

Colossians 2:16
Therefore let no one judge you by what you eat or drink, or with regard to a festival, a New Moon, or a Sabbath.

Colossians 2:21-23
"Do not handle, do not taste, do not touch!"? . . .

Hebrews 9:10
They consist only in food and drink and special washings--external regulations imposed until the time of reform.