There have been several metal bands named "Impurity", two of which are active:

1) IMPURITY (POL). Polish death metal band formed in 1987 (inactive).
Releases:
Immense Decay (Demo) 1989
In Pain We Trust (Demo) 1990

2) IMPURITY (BR). A Brazilian black metal band formed in 1988, with 4 albums (The Lamb's Fury - 1993, Into The Ritual Chamber - 1996, Satanic Metal Kingdom - 2004, Necro Infamists of Tumulus Return - 2006) and one EP (Guests of the Infernal Pit - 2004) released. Signed with Cogumelo Records.

3) IMPURITY (US). A North American death metal band formed in 1998 and based out of Gainesville, Florida.

Releases:
Subjugation of Mankind - EP, 1999 (Self-released)
Unearthly Affinity - EP, 2003 (Nuclear Winter Records)
Of Lust and War - Full-length, 2007 (Butchered Records)
Promo 2009 - EP, 2009 (Self-released)

Current lineup:
Damian Scott - vocals (since 2007), guitars (1998-2007)
Jeremy Caldwell - guitars (since 2003)
Michael Lindenmuth - guitars (since 2011)
Justin Wood - drums (since 2008)

4) IMPURITY (AUS). Melodic Death/Black Metal from Austria. Formed in 1990, they released 2 EPs + 2 LP/CDs.

5) IMPURITY (CAN) Melodic Black Metal from Canada. Year of creation: 95. Released 1 demo in 97. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.