Lead and tin compounds have anti-fungal and anti-bacterial effects.
http://www.springerlink.com/content/n55772025q382801/
Many metallic salts have medicinal properties, and some are necessities of life. Dosage has some effect, too. Too much salt will kill you, not enough will kill you; you must find the balance point in there somewhere. Same with oxygen, another element that forms many compounds, some useful, some harmful.