Removal of Amalgam Fillings Associated With Reductions in Memory Loss, Fatigue, Anxiety, Confusion & Other Health Problems, Observational Study from Canada Shows

Amalgam removed = health restored?

While there is little doubt that mercury vapor poses a known health risk, there is neither a clearly established safe level of exposure, nor evidence that similar ill health effects can occur with chronic low grade exposure to mercury vapor from dental amalgam fillings.

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).

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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)

A brief glimpse at the baseline data reveals that the presence of 18.4 and 23.7 amalgam fillings on the tooth surfaces of the subjects in the treatment (amalgam fillings will be removed) and the amalgam control group (amalgam fillings will not be removed) have higher amounts of mercury in their urine.

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)

The effects are, I guess you will agree with me on that one, not exactly impressive. Against that background the obvious question is: "Are the self-reported measured improvements in headache, memory loss, depression, fatigue, anxiety & co a result of a placebo effect?" I mean, the subjects obviously knew that their amalgam fillings were removed (remember: it's a non-blinded study!) and you bet that they've read some of the horror stories about mercury on the Internet.

Table 1: One year odds of symptom improvement and worsening in the group of subjects who had the amalgam fillings removed, controlled for age and sex | Odds ratio coefficients are the odds of change in treatment group relative to the positive amalgam group. {P values}; * indicates coefficient is different from 1 at size 0.05; ^ represents statistical significance at size 0.10 (Zwicker. 2014).

So, can we tell whether the "improvements" you see in Table 1 are actually brought about by the removal of the amalgam fillings or simply by the subjects psyche? I would say we can't and that's why I have my doubts about the validity of the researchers conclusion that "that mercury exposure from amalgam fillings adversely impact health and therefore are a health risk" (Zwicker. 2014) - not necessarily because I believe they are harmless, but rather because the data the scientists evaluated does not prove this claim.

If avoiding mercury from fish is a good thing, avoiding mercury exposure from amalgam fillings is a good thing, too. Irrespective of the fact that the study at hand provides only insufficient evidence of its ill health effects.

Bottom line: I personally had my one filling removed back in the day, but rather the necessary result of the fact that it was in a baby tooth ;-)

That being said, I still subscribe to the researchers assertion that "a safer alternative materials for dental fillings should be encouraged to avoid the increased risk of health deterioration associated with unnecessary exposure to mercury" (Zwicker. 2014), yet not because of the data in the study at hand, though, but rather based on the notion that you would want to limit any unnecessary exposure to heavy metals, no matter how small the amount that's leeching from the amalgam fillings may be, though.

On a side note: A study investigating the commonly heard claim that the removal of amalgam would only increase the load of mercury (at least temporarily) indicates that - if it's done properly - "[t]he uptake of amalgam mercury in the GI tract in conjunction with removal of amalgam fillings seems to be low" (Björkman. 1997). So if you are considering this procedure, it's unlikely that it will make whatever symptoms you believe to have as a consequence of having amalgam fillings more severe | Comment on Facebook!

References:

• 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.