However, significant differences in urinary mercury concentrations between boys and girls with comparable levels of amalgam treatment and times since placement suggest sex-related differences in mercury handling and, possibly, susceptibility to mercury toxicity.
In the meantime, given that mercury is highly neurotoxic and there is no established benefit at any level of mercury, removing amalgam fillings to prevent future buildup of mercury in the brain may be important to reduce the risk of health deterioration.
Autopsy studies have shown that elevated brain mercury levels are correlated with number of amalgam fillings and individuals with more than 12 amalgam fillings have more than 10-times higher mercury levels in several tissues including the brain, compared to individuals with only 0 3 amalgam fillings [ 66, 67].
While it is clear that mercury vapor is toxic, there is debate over whether the level of exposure resulting from dental amalgam fillings is sufficiently high to produce toxic effects in the body.
Other groups like the Human Biomonitoring Commission (HBM) of the German Federal Environment Agency determined that published scientific evidence and expert opinion demonstrates that there "is no risk for adverse health effects and, consequently, no need for action" for the level of mercury exposure from dental amalgam below the HBM-I level (5 μg/g-creatinine) [ 29].
A study by Richardson [ 32] translated the dose associated with amalgam exposure to compare to the Canadian chronic reference exposure level (REL) and found that the maximum number of amalgam surfaces was 4.4 and 7.3 for females and males respectively, before exceeding the Health Canada REL for Hg of 0.011 μg/kg-day.
This study evaluated the effects of amalgam restorations on plasma mercury levels and total antioxidant activities (TAA).
In addition, information on amalgam fillings was collected, but there was no correlation between the presence of amalgam fillings and blood Hg levels.
Mercury level in amniotic fluid is weakly associated with number of amalgam fillings (Luglie et al. 2005).
The mean urine mercury level of participants with one or more amalgam surfaces is about double that observed for the participants with 0 dental amalgam surfaces (1.61 μg/g-creatinine and 0.78 μg/g-creatinine respectively (Wilcoxon signed-rank test, p <0.001, Table 1 and Figure 1).
