http://www.healthobservatory.org/library.cfm?RefID=105040

The link is the amount of mercruy found in processed foods due to the corn syrup

I was trying to figure out the amount of mercury in tuna for comparison, as it is 0.5 ppm, and from my calcs that would equal 500,000 ppt. I needed ppt because all the data in that above link is in ppt (parts per trillion, as opposed to parts per million)

That means that the mercury content of tuna is still 1,400x higher than Quaker oatmeal, the food with the highest detected amount of mercury in it from HFCS. So its not an extreme exposure by any means, but HFCS raises many other health issues besides just having a bit of mercury.