The study design has been documented to not have been a serious effort to determine amalgam safety in children, as the design was badly flawed and could not in its form determine the safety of amalgam fillings. As documented here, the study was an unethical use of a known highly toxic substance on children, who were not fully informed or in a position to understand the implications. The authors’ interpretation of results is also questionable because the study is shown to not have been structured to assess the main, known health effects related to mercury exposure from amalgam, and the authors disregarded the thousands of peer-reviewed studies that previously documented the harm caused by mercury.
Based on thousands of studies and millions of tests by medical labs, dental amalgam is the largest source of mercury exposure in most adults and children who have several amalgam fillings. Those with amalgams get significantly higher mercury exposure than those without. Mercury accumulates in the brain and major organs proportionately to the number of amalgam fillings and commonly causes chronic degenerative neurological conditions later in life.
Under the Proposition 65 procedures passed by the state of California in 1986, mercury has been determined to be a reproductive toxin and to cause birth defects. Many studies have also documented this. Thus, products that use mercury and cause significant mercury exposure must provide warnings to the public of the known health risk. Use of dental amalgam by dentists in California requires such a warning. Several other states have passed similar laws requiring warnings by dentists of the known health risk related to use of dental amalgam. Dental amalgam has been documented by tests at medical labs to be the largest source of mercury exposure for most people who have several amalgam fillings. A mother’s dental amalgam has been documented to often be the largest source of mercury to the fetus and to young infants, with levels in the fetus and infant often higher than the mother’s blood level.
A study at the U.S. CDC found “statistically significant associations” between neurological developmental disorders, such as autism, attention deficit disorder (ADD) and speech disorders, with exposure to mercury from thimerosal containing vaccines before the age of 6 months. An analysis of the U.S. CDC VAERS database for adverse reactions from vaccines regarding effects of the diptheria-tetanus-pertusis vaccine found that those receiving DTaP and DTucP vaccines with thimerosal had significantly higher rates of autism, speech disorders, and cardiac arrest than those receiving DtaP vaccine without thimerosal, and the analysis also found that the rate of these increase exponentially with dose. An analysis of the U.S. Dept. of Education report on the prevalence of various childhood conditions among school children found that the rate of autism and speech disorders increased with increasing levels of thimerosal exposure from vaccines.
A follow-up study using DMSA as a chelator found that mercury concentrations in urine were significantly higher overall in children with autistic spectrum disorders than in a matched control population, and the study found that vaccinated cases showed significantly higher urinary mercury concentrations than vaccinated controls. This is consistent with other studies that found that those who are poor excreters of mercury are more likely to accumulate mercury and have adverse health effects. A significant portion of children and adults have been documented to have this problem due to blood allele type or metallothionein deficiencies.
A study of environmental mercury levels in Texas school districts found a 61% increase in autism and a 43% increase in special education cases for every 1,000 pounds of mercury released into the environment. Autism prevalence diminished by 2% for every ten miles of distance from a mercury source. Another similar study found similar results. Fossil fuel-burning power plants were the largest source of the widespread mercury pollution, but dental amalgam was the largest source in sewers and a significant source of environmental mercury in water bodies, fish, and air emissions.
Thus the ethics in the exposure to a group of children to higher levels of a very neurotoxic substance such as mercury is highly questionable, along with the fact that the study had no mechanism for assessing long-term accumulation of mercury in body organs, future cumulative mercury health effects, or synergistic effects with other future toxic exposures, which have been documented well in medical literature.
This study was not a serious test of the safety of amalgam since the exposure was to children with no previous amalgam fillings at relatively low levels of exposure for a very limited period of time. The mean number of restored amalgam surfaces in the mouth of the amalgam group at the end of the study was only four amalgam surfaces. While the urine mercury level in the amalgam group was 50% higher than the non-amalgam group, the differential is much lower than in most studies of groups or either children or adults with and without amalgams.
However, even with the low exposure levels, it is not clear from the study results that there were no significant adverse effects of amalgam shown as claimed by the authors. For example, it is documented that mercury from amalgam commonly causes chronic neurological conditions in adults. Therefore, it might be useful to compare diagnosed neurological conditions between amalgam and non-amalgam group. The comparison is as follows:
Similarly while the authors state that there were no significant renal effects observed, it could be noted that the unadjusted mean albumin level at year 5 for the amalgam group was 38% higher than for the non-amalgam group. I would be very concerned about the future of some at the high end of the amalgam group albumin levels.
Comments on Second Children’s Amalgam Study
De Rouen, et al. Comments on “neurobehavioral effects of dental amalgam in children. JAMA. 2006.
This study, like the other children’s amalgam study, represented an unethical use of a known highly toxic and immune reactive substance on children and was not designed to determine the long-term health effects of amalgam use, which has been documented in the comments on Study 1 in this paper.
To justify the study design, the authors’ state, “there is little or no evidence concerning health effects of low level mercury exposure from amalgam, especially in children” (p. 1). In fact, there are over 3,000 peer-reviewed studies in the medical literature that were submitted by parties in the FDA amalgam docket to the FDA that document the mechanisms by which amalgam mercury accumulates in all major organs and commonly causes over 30 chronic health conditions. And there are hundreds are peer-reviewed studies and clinical studies that document that many thousands of patients with these conditions have improved after amalgam replacement. While it is clear that many children have had their health adversely affected by mercury as there are multiple exposure mechanisms and synergistic effects with other toxic substances, it’s not clear the extent to which dental amalgam is primarily responsible or just a contributor with other exposures.
The main problem with the study design appears to be the choice of what conditions were tested for and the kinds of tests that were used. In describing why the chosen conditions were tested for and in what manner, the authors stated that the study reviewed organs for elemental mercury exposure from amalgam; the organs identified to be within the renal system and those with neurological functions (memory, attention/concentration, and motor/visuomotor) (p. 2).
Actually, while there is documentation in the medical literature of many other types of health effects, there is little evidence in the literature on common renal effects. However, there are other types of health effects that have been documented in the literature to be more commonly caused by mercury.
The following analysis shows that the basic assumptions that the authors say they based their study design on were not valid, and the study does not demonstrate what it has been suggested to demonstrate. In fact, due to the poor study design, the study is not very useful. It had been documented by millions of medical lab tests that those with amalgam fillings commonly have mercury exposures between five and ten times that of the average person with no amalgams. In addition, mercury accumulates in the brain and major organs in direct proportion to the number of amalgam surfaces. It has likewise been documented in the medical literature by thousands of studies that mercury and other toxic metals exposures are synergistic and cumulative and commonly cause chronic autoimmune, neurological, hormonal, and reproductive problems later in life, depending on individual susceptibility.
Thus, it was clear that the study design, which exposed children to a known highly neurotoxic and immunotoxic substance that commonly causes adverse effects, was highly unethical. The effects that might happen in the early years of exposure have little relevance to whether amalgam is safe as a filling material. The study was not designed to determine anything about the long-term health or safety effects on this population of children.
Questionnaire results of 1569 patients regarding health problems that have been documented to be commonly caused by mercury toxicity found the following distribution:
Similar patterns and recovery results after amalgam filling replacement have also been documented in a larger group of over 60,000 patients. Thousands of peer-reviewed studies documenting the mechanism by which mercury commonly causes these conditions are in the literature. It is seen that there are eight major types of health conditions known to be caused by mercury that are more commonly seen in the population than the types of conditions that these studies chose to attempt to test for. In all of those types of conditions, peer-reviewed studies and clinical studies found that the majority of those who had amalgam fillings replaced properly had health improvement after replacement. There are few studies that document significant renal effects from dental amalgam exposure, so it’s not clear why the authors chose to test for renal effects. There is some question as to what the study being reviewed actually measured regarding neurological effects since other studies have documented that mercury from amalgam and other toxic metals commonly causes ADD/attention deficit as well as memory problems and that the majority with such conditions usually improve after amalgam replacement.
It should also be noted that since the effects of toxic exposures are known to be synergistic and cumulative, the results of a study in one country or population do not necessarily apply to another country or population, which may have significantly different patterns of toxic exposures.
- Geier MR, Geier DA. Neurodevelopmental disorders following thimerosal-containing vaccines. Ex Biol Med.2003.
- Geier MR, Geier DA. Thimerosal in childhood vaccines, neurodevelopmental disorders, and heart disease in the U.S.
J of Amer Physicians and Surgeons. 2003; 8(1).
- Bradstreet J, Geier DA, et al. A case control study of mercury burden in children with autistic spectrum disorders. J of Amer Physicians and Surgeons. 2003; 8(3).
- Geier DA, Geier MR. A case series of children with apparent mercury toxic encephalopathies manifesting with clinical symptoms of regressive autistic disorders. J Toxicol Environ Health A. 2007; 70(10): 837-51.
- Palmer RF, et al. Environmental mercury release, special education rates, and autism disorder: An ecological study of Texas. Health and Place. 2005.