I hear that (aside from that old saw, the dihydrogen monoxide poisoning gag), even clean water in too high a dose can kill you.
#6
figmentPez
I don't know what the current state of research is, but what I last read was that Vitamin C helps prevent cancer... unless you take too much of it, at which point it's correlated with higher cancer rates. (I think the study was inconclusive on if it caused the cancer, or just made other cancer-causing agents to be more effective, or something like that.)