If mercury is toxic enough to create these effects hundreds of miles from the nearest source, is it really wise to have a source of it in our mouths? Perhaps it is time to consider replacing old fillings with tooth-colored fillings or a dental crown.
Mercury Contamination in Isolated Lakes
NPS tested mercury levels in fish in 21 national parks. Every site had some amount of mercury.
One fish in Yosemite National Park was determined to be so hazardous that no one should eat it. About 5% of fish had mercury levels high enough to cause tumors and other health effects in the fish themselves. About 35% of fish had mercury levels high enough to result in poisoning of fish-eating birds, which build up mercury in their system over time. And 68% of fish had mercury levels that meant people should be careful about the amount of fish they ate.
Water gets contaminated by mercury more than land because aquatic bacteria are good at converting mercury into methylmercury, an even more deadly form. Like fish-eating birds, predatory fish build up mercury over time.