|Amalgam removed = health restored?|
As you may know amalgam is not 100% but "only" 50% mercury, but is that enough to represent a significant health risk? The objective of a recent study from the University of Calgary was "to determine if mercury exposure from amalgam fillings is associated with risk of adverse health effects" (Zwicker. 2014).
To this ends, Zwicker et al. conducted a large longitudinal non-blinded study involving participants from a preventative health program in Calgary, Canada. The goal was to assess whether (a) there was an association between having amalgam fillings, the amount of mercury in the urine and reported health issues and (b) whether the 14 previously self-reported health symptoms would improve in a sample of persons who had their fillings removed compared to a sample of persons who had not had their fillings removed.
|Figure 1: Summary data for study sample with urine mercury measures (Zwicker. 2014)|
What do previous studies say? Oskarsson et al. (1996) fount that mercury from amalgam fillings was the main source of mercury in milk. In fact, the amount of mercury babies were exposed to from breast milk ranged up to 0.3 μg/kg/d, of which approximately one-half was inorganic mercury and which corresponds to approximately one-half the tolerable daily intake for adults recommended by the World Health Organization (Oskarsson. 1996). Other studies present opposing results, though, and claim that fish, not amalgam fillings was the major source of mercury in breast milk (Drexler. 1998). Still, evidence from other studies, such as Nylander (1987), which report mercury vapor from amalgam fillings to be the major source of mercury in the organs of human subjects, support the notion that at least the "first generation" amalgam fillings are a major source of human mercury exposure. The correlation with subjective health symptoms, on the other hand, is less obvious. Studies like Ahlqwist et al. (1988) and a twin study by Björkman et al (1996) clearly refute the existence of a significant correlation.What is interesting, but not actually what the scientists wanted to investigate is the fact that the mercury levels in women are generally higher (may be a result of a comparatively lower body size and mass and similar mercury exposure).
What do you think happened one year after the fillings were removed?
Well, let's see. As the data in Figure 2 indicates, the mercury levels in both amalgam groups declined in comparison to the baseline measure (follow up data for the amalgam free group is not available)
|Figure 2: Changes in mean urinary mercury level after one year after the amalgam fillings |
were removed / not removed (Zwicker. 2014)
- Ahlqwist, Margareta, et al. "Number of amalgam tooth fillings in relation to subjectively experienced symptoms in a study of Swedish women." Community dentistry and oral epidemiology 16.4 (1988): 227-231.
- Björkman, Lars, Nancy L. Pedersen, and Paul Lichtenstein. "Physical and mental health related to dental amalgam fillings in Swedish twins." Community dentistry and oral epidemiology 24.4 (1996): 260-267.
- Drexler, Hans, and Karl-Heinz Schaller. "The mercury concentration in breast milk resulting from amalgam fillings and dietary habits." Environmental research 77.2 (1998): 124-129.
- Oskarsson, Agneta, et al. "Total and inorganic mercury in breast milk and blood in relation to fish consumption and amalgam fillings in lactating women." Archives of Environmental Health: An International Journal 51.3 (1996): 234-241.
- Nylander, Magnus, Lars Friberg, and Birger Lind. "Mercury concentrations in the human brain and kidneys in relation to exposure from dental amalgam fillings." Swedish dental journal 11.5 (1986): 179-187.
- Zwicker, Jennifer D., Daniel J. Dutton, and John Charles Emery. "Longitudinal analysis of the association between removal of dental amalgam, urine mercury and 14 self-reported health symptoms." Environmental Health 13.1 (2014): 95.