Amalgams contain about 50% mercury. It's proved that mercury leaches out & accumulates in brain, liver, kidneys...
Lars Friberg was one of the researchers.

The following link is to a web page that contains a link to a Panorama programme, and a link to a transcript of the television programme.

http://zakstar.wordpress.com/2008/01/29/silvermercury-amalgam-fillings/
This is really worthwhile watching.
If it "sticks" at all, just move the slide slightly in front, this worked for me.

Contains good footage of the xrays of a sheep where the mercury had spread, and much more.