Mercury pollution attributed to industrial activity..
But it also goes way back in medicine and time..

History and use of mercury for millennia..
"Birth of Greek God mercury "
A statue and look at the pole the statue is holding..

http://www.corrosion-doctors.org/Elements-Toxic/Mercury.htm

Mercury has been found in Egyptian tombs indicating....
It was used as early as 1500 BC..
Who knows it may go even further back then that..
There has been alot of lost history but that doesn't mean..
It didn't go way back in time beyond even longer ago ...

http://www.emedicine.com/EMERG/topic813.htm