We’ve known for years that mercury from “silver” amalgam fillings shows up in urine. We also know there’s a correlation between the number of fillings a person has and urinary mercury levels. Earlier analyses found that about 10% of American adults get a daily dose of mercury vapor that’s above the EPA safety limit. Among pregnant women, that figure rises to 28%.
We blogged about some of this research before.
Now, new research in Clinical Chemistry and Laboratory Medicine sheds light on how mercury moves through the body to get to the kidneys.
Hypothesizing that “blood provides a significant avenue for Hg [mercury] vapor released from amalgams to transverse the human body,” the study’s sole author analyzed NHANES data from more than 1300 American adults to find out. Blood mercury levels of those with amalgam fillings were compared to the levels of those with mercury-free mouths.
The results were clear:
- Blood mercury levels were higher in people with amalgam fillings. Both total and inorganic mercury concentrations were elevated.
- The relationship was dose-dependent. The more amalgam surfaces a person had, the higher their blood mercury levels. (A single filling can have multiple surfaces. Counting these instead of just the number of fillings gives a more accurate measure of amalgam exposure.) When the author calculated the estimated daily doses of mercury vapor, those doses correlated with blood mercury levels.
- The correlations held up across multiple statistical models – both with and without adjustments for age, weight, and other factors.
“The results observed in this study,” the author notes,
are biologically plausible as to the importance of blood as an important transport avenue for Hg dose-dependently released by amalgams. It is known that Hg vapor is readily absorbed in the lungs (80 % absorption percentage) and quickly diffused into the blood and distributed into all body organs
It also crosses biological barriers easily, including the blood-brain barrier and the placental barrier. Once it reaches tissues and is oxidized, the body struggles to excrete it.
Unfortunately, as the study notes, blood mercury levels don’t tell us exactly how much has accumulated in the brain, kidneys, or other organs – although testing is available to assess a person’s body burden. What blood mercury levels do confirm, though, is that mercury is actively circulating throughout the body.
Certainly, this study, like all studies, has limitations worth noting. For one, it’s cross-sectional, a snapshot in time. It doesn’t count for the age or copper content of the amalgams either, both of which influence mercury release rates). Still, it adds to the story of what happens with amalgams once they’re in a person’s mouth.
If you have “silver” fillings and are concerned about mercury exposure, the first thing to do is to consult with a well-trained biological dentist. They can conduct the appropriate exams and testing to evaluate the impact amalgam may be having on your whole body health. They can talk with you about the pros and cons of amalgam removal specific to your unique situation.
Should you ultimately decide to have your amalgams replaced with biocompatible restorations, safe removal of those old fillings is crucial. The evidence-based SMART (Safe Mercury Amalgam Removal Technique) protocol, developed by the International Academy of Oral Medicine and Toxicology (IAOMT), provides specific guidelines to minimize mercury exposure during the removal process.
You can learn much more about SMART here.
