Metallic Taste Beer

What gives a metallic taste a few beers?
Is there any danger if a metallic taste beer?
Cans could be giving it a strange taste, hard water used in processing, or beer to get exposed to light (if in a bottle). If this is a project could take advantage of bad lines. Nevertheless, no danger to you, it just does not taste as good
Matt’s Beer Reviews: Dale’s Pale Ale and Children of Men Pairing