Apparently you cannot clean up mercury pollution, you can only bury it. Mercury damages the nervous system, and people who ingested large amounts of mercury-contaminated fish were blinded, paralyzed, and children were born retarded. At least a 1000 people died of the disease. The Japanese experience with mercury poisoning was a horrifying example for the rest of the world, but similar atrocities continue to occur in many industrialized countries. Mercury levels in free-swimming ocean fish do not appear to be a problem.
Dental amalgams provide a constant source of elemental mercury.
Daily intake of mercury in uncontaminated food is in the range of 15 -20 micrograms per day. Battery action in the mouth from metal fillings induces an odd electrolytic food chemistry, bad tastes, and makes teeth brittle. Dental mercury is just another chemical pollution problem to add to our very long list of problems. Do not have all your amalgams replaced until you have solved other, bigger problems first, especially food problems. Do ask for non-mercury fillings if new ones must be placed.