Is Dental Amalgam Safe for Humans?
The following has been extracted from a full length article by Dr Joachim Mutter entitled Is Dental Amalgam Safe for Humans? The Opinion of the Scientific Committee of the European Commission.
Dr Mutter works at the Department of Environmental and Integrative Medicine in Konstanz, Germany and this article was published in the Journal of Occupational Medicine and Toxicology in January 2011 and is his rebuttal of a report to the European Union Commission by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) addressing the safety of amalgam.
Click for the full SCENIHR report which concluded that there were ".. no risks of adverse systemic effects" and that "the current use of dental amalgam does not pose a risk of systemic disease."
In his response, Dr Mutter takes issue with almost every aspect of the report including the composition of the committee itself which was comprised of over half dentists. He states that the SCENIHR report reveals much deeply flawed science and fundamental misunderstandings about the nature of mercury (Hg) toxicity. And also that the committee failed to include many of the most important scientific studies in their review often basing opinions with regard to specific topics on just one or two research papers. In addition, most of the studies cited by SCENIHR report which conclude that amalgam fillings are safe have severe methodological flaws.
The tendency is always for any group to tend towards the norm and to underestimate the possibility of disastrous effects and this is known as group think. This is because people simply have difficulty comprehending and dealing with something that they have not experienced before and tend to place the most optimistic possible interpretations upon obvious warning signs and to seize ambiguities to infer a less serious situation and this appears to have been the case with this report.
In his article Dr Mutter makes the following points (added emphases are mine):
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Dental amalgam is by far the main source of total mercury body burden in humans. This has been proven by autopsy studies which found up to 12 times more mercury in body tissues of individuals with dental amalgam.
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Autopsy studies are the most valuable and most important means available for examining the amalgam-caused mercury body burden and consistently show that individuals with amalgam fillings have toxic levels of mercury in their brains and/or kidneys.
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There is no correlation between mercury levels in blood or urine and the levels in body tissues as determined at autopsy or the severity of clinical symptoms. And yet the SCENIHR only relied upon mercury levels measured in blood or urine.
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The half-life of mercury in the brain can last decades, thus the bodily burden of mercury accumulates over time on exposure to dental amalgam fillings steadily reaching toxic levels. However, in the report, the SCENIHR fail to consider this and stated that the half-life of mercury in the body is only '20-90 days'.
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Mercury vapour is about ten times more toxic than lead to human neurons and shows considerable synergistic toxicity with other metals.
Dental amalgam and mercury body burden
Because mercury exposure is hard to measure directly, many studies use blood and urine levels as indications of mercury exposure in humans. And whilst blood and urine mercury levels are approximately 2-5-fold higher in subjects with dental amalgam fillings, tissue levels at autopsy are found to be up to 12 fold higher so that measurements in blood and urine are a poor indicator of tissue levels. Animal studies confirm these findings.
In a recent autopsy study, individuals with more than 12 amalgam fillings were found to have more than 10-times higher mercury levels in several tissues including the brain when compared to individuals with three or fewer fillings. The average mercury level in the brains of European citizens with more than 12 amalgam fillings was 300ng Hg/g brain tissue, which is over ten times the mercury levels proven to be toxic in vitro on neurons (0.02 - 36ng Hg/g).
In another autopsy study, those with more than 10 amalgam fillings had nearly ten times the levels of mercury in their kidneys as those with two fillings or fewer and levels five times higher in the liver. Mercury had also accumulated at high levels in the thyroid and pituitary glands and this correlated significantly with numbers of amalgam fillings.
It is also worth noting that these figures represent only averages and a significant portion of individuals with dental amalgam have in excess of twice these levels in their tissues. Also that mercury concentrates in cell organelles such as mitochondria (which produce energy) and microsomes at many times these average levels.
According to these studies, dental amalgam is responsible for at least 60-95% of mercury deposits in human tissues and this was not acknowledged by SCENIHR.
The report stated that there was no evidence of conversion of mercury from amalgam by oral bacteria. But studies have shown that mercury from dental amalgam is transformed into organic mercury compounds by microorganisms in the human gastrointestinal tract. In one study researchers found a three-fold increase in salivary methyl mercury levels in subjects with dental amalgam fillings compared to individuals without amalgam, although frequency and kind of fish consumption were identical in both groups.
In fact, mercury levels in saliva exceed mercury limits for sewage in 20% of individuals with amalgam. And the form of methyl mercury derived from dental amalgam may be up to 20 times more toxic than the form of methyl mercury found in fish.
Even low levels of inorganic mercury led to the total destruction of intracellular microtubules and to the degeneration of neurons and to oxidative damage.
Brain pathology and mercury
Alzheimer's disease (AD) The report questioned the proposed causative role of mercury in Alzheimer's disease citing only one study published in the journal of the American Dental Association, but other studies and a recent systematic analysis of the literature regarding the role of mercury in AD found a significant association. The average mercury load in brain tissues and pituitary glands of individuals with Alzheimer`s disease was high and well above established toxic levels.
In Germany, approximately 20% of people aged around 20, 50% aged around 50, and 90% aged 85 show pathological changes in their brains that are typical for Alzheimer's disease and mercury toxicity. This pattern of pathological brain changes is caused in experiments by very low levels of mercury but not by low levels of other metals such as lead, iron, aluminium, copper, manganese, chromium or cadmium. This may reflect the frequency of dental amalgam fillings in humans since about 80-90% of the population of Germany have had dental amalgam fillings over a period of decades.
About 30-50% of Germans over the age of 85 have Alzheimer's disease (AD) and there are many hints that mercury is playing a major pathogenic role. At the mercury levels humans with several amalgam fillings are exposed to pathological degenerative changes occurred in the brains of animals after just 14 days.
It is also possible that individual susceptibility to mercury toxicity as a result of a genetic polymorphism of coproporphyrinoxidase (CPOX4) may lead to increased susceptibility to neurological damage from mercury and thus to a higher risk for AD.
Amyotrophic Lateral Sclerosis (ALS) The report dismisses the possibility of a link between Amyotrophic Lateral Sclerosis (ALS) and mercury, but again, there are many studies which suggest that mercury may play a pathogenic role in ALS. In experiments, mercury vapour was found to promote motor neuron diseases such as ALS and there is a correlation between accidental mercury exposure and ALS. There is a case report of a Swedish woman with ALS who recovered after having her 34 amalgam fillings removed. And a retrospective study reported a statistically significant association between an increased number of amalgam fillings and the risk of motor neuron diseases such as ALS.
Parkinson's disease (PD) Heavy metals have long been suspected to be a cause of PD, with several studies including epidemiological studies showing a relationship. Elemental mercury has induced PD, and in a case report, the symptoms of Parkinson's disease substantially improved after treatment with a mercury chelator and remained improved during a 5-year follow-up period. In another study, significantly elevated blood mercury levels were found in 13 of 14 patients with PD compared to healthy controls. This supports the conclusion of a previous study which found a correlation between blood mercury levels and PD. Another study found significantly higher amalgam exposure in individuals with PD compared to healthy controls.
Multiple Sclerosis (MS) Mercury levels in the cerebrospinal fluid (CSF) of MS patients was found to contain over 7 times the mercury of those not affected. This may be the cause or an exacerbating factor. Also, the prevalence of MS has been shown to be correlated with the prevalence of both decay and amalgam. Several MS epidemics occurred after acute exposure to mercury vapour or lead and animal studies confirm damage done to neurons by mercury and other heavy metals.
MS patients who have had their amalgam fillings removed showed improvements in behaviour and mood compared to those who still had their fillings and they also had significantly lower levels of mercury in blood and markers in the CSF improved. Removal of dental amalgam has also led to a recovery in a significant proportion of MS patients. A retrospective study on 20,000 military individuals revealed a significantly higher risk for MS in individuals with more amalgam fillings. In spite of various limitations, a reanalysis found a nearly 4 fold increased risk for multiple sclerosis in individuals with amalgam compared to individuals with no amalgam.
Generational transmission of mercury toxicity
Maternal amalgam fillings lead to a significant increase of mercury levels in foetal and infant body tissues including the brain. Furthermore, placental, foetal and infant mercury body burden correlates with the number of amalgam fillings of the mothers. Mercury levels in amniotic fluid and breast milk also significantly correlate with the number of maternal amalgam fillings.
Drasch et al. found mercury levels of up to 20ng Hg/g in German infant brain tissues which were mainly caused by the dental amalgam fillings of their mothers. Mercury levels of just one-thousandth that level - 0.02ng Hg/g - have been shown to cause degeneration of nerve axons.
Furthermore, the mercury levels found in the brains of infants whose mothers had dental amalgam fillings were sufficient to inhibit the function of the important enzyme methionine synthetase. This enzyme is critical to methylation, which is a crucial step for most important metabolic reactions in the body including the development of the brain, the maturation of nerve cells and the production of neurotransmitters.
Maternal amalgam fillings also increase significantly mercury levels in umbilical cord blood. The risk for delayed neurodevelopment of children was increased 3.6 times when mercury levels in cord blood were higher than 0.8ng Hg/ml. This falls within the range considered 'normal' in Germany, thus exposing many infants to mercury levels that may cause neurodevelopmental deficits.
Urine, blood and hair levels are NOT biomarkers for body mercury
The SCENIHR report is based on studies which have used measurements of mercury in urine, blood or hair to assess the clinical symptoms of mercury body burden. However, the WHO stated in 1991 that "Mercury typifies a 'retention' toxicity and much of the mercury taken into the body is absorbed by the solid tissues. The amount in urine represents mercury being excreted. However, the main question is how much is being retained in the different body tissues".
It has been shown in both animal and human experiments that in spite of normal or low mercury levels in blood, hair and urine high mercury levels are found in critical tissues such as brain and kidney. A recent autopsy study confirms that there is no correlation between inorganic mercury levels in urine or blood and mercury levels in brain tissues.
Drasch and coauthors have shown that 64% of individuals occupationally exposed to mercury vapour and having typical clinical signs of mercury intoxication had urine levels of mercury below 5μg/l, which represents the No Observable Adverse Effects Level (NOAEL). The same results were found for mercury levels in blood and hair.
There is even a paradoxical correlation between mercury levels in urine, blood or hair and clinical symptoms. This means that subjects with highest urine levels of mercury showed best recovery rates from neuropsychological complaints after removing their amalgam fillings. Also children with the highest mercury levels in their hair showed better performance in developmental tests.
Another study indicates that in spite of a significantly higher exposure to mercury in their mother's womb, autistic children had up to 15-times lower mercury levels in their hair than healthy children. Furthermore, the lower the mercury levels in infant hair, the higher was the severity of autism.
Despite higher mercury body burden, an 'amalgam hypersensitivity' group showed slightly lower levels of mercury in their saliva, blood and urine than a healthy control group. Even after provocation with the mercury chelator DMPS, the 'amalgam hypersensitivity' group excreted an average of only half the mercury in urine of the healthy amalgam bearers.
Furthermore, studies confirm that the ratio of faecal to urinary excretion of mercury is 12 to 1. This proves that the majority of excreted mercury leaves through the biliary transport system of the liver via the faecal route. Urine mercury therefore represents a minor excretory route of less than 8% of mercury being excreted. Also, urine mercury is a measure of mercury being excreted by the kidney - not a measure of total mercury body burden.
Mercury 'allergy' rare?
With regard to mercury sensitivity, the SCENIHR only accept a positive cutaneous patch test as proof and yet 90% of mucosal lesions have been found to recover by removal of amalgam fillings, irrespective of patch test results. This may indicate that cutaneous patch testing is not a viable or sensitive test for mercury sensitivity.
In addition, mercury sensitive persons are significantly more likely to be carriers of the apolipoprotein E4-allele (APO-E4) than symptom free controls and are less likely to carry the APO-E2 allele. APO-E4 is known to be the major genetic risk factor for Alzheimer's disease, whereas APO-E2 decreases the risk. It has been postulated that this is due to the difference in capacity to remove heavy metals from the cerebrospinal fluid.
Establishing safety levels for mercury exposure
In view of the data presented above, it is impossible to determine any safety levels below which the adverse effects of exposure to mercury can be excluded. SCENIHR used safety limits which were deduced from studies with workers occupationally exposed to mercury. However, these limits cannot be applied to individuals with amalgam fillings and must be critically evaluated because:
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Frequently, mercury exposure of workers in the chloralkali industry is used for comparison although the simultaneous exposure to chlorine considerably diminishes the absorption of mercury into the body tissues of animals by 50-100%.
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Workers exposed to mercury usually represent a group whose mercury-exposure started in adulthood (for about 8 hours a day, 5 days a week), while those exposed to mercury from dental amalgam can be exposed from the gestation to death at a rate of 24 hours per day, 7 days per week.
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Workers are not representative of society at large with the more vulnerable pregnant women, infants, children and individuals with illnesses often unable to work at all not included in the studies.
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Despite mercury exposure below 'safety limits', significant adverse health effects were found in most studies in workers exposed occupationally to mercury, even several years after the exposure had ceased.
The unique toxicity of mercury
SCENIHR did not mention the specific toxicity of mercury vapour coming off dental amalgam fillings. The SCENIHR paper stated that the body half-time (of mercury) is '20-90 days', when, particularly in the brain, mercury has a significantly longer half-time of more than 17 years.
Mercury has been shown to be 10 times more toxic than lead in vitro. Mercury is the most toxic non-radioactive element and its vapour is one of the most toxic forms of mercury along with some of the organic mercury compounds. This extraordinary toxicity is also determined by the following properties:
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Mercury is the only metal which is a gas at room temperature, which is readily absorbed (80%) by the respiratory system.
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Mercury vapour from amalgam is able to penetrate into tissues with great ease, because of its monopolar atomic configuration.
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Once inside the cells, mercury vapour is oxidised to Hg2+, the very toxic form of mercury which binds covalently to thiol groups of proteins inhibiting their biological activity.
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Hg2+ is more toxic than the equivalent ions formed by other metals such as lead or cadmium because it has a higher affinity to to bond irreversibly with thiol groups (cysteines in proteins). Other metals form reversible bonds with proteins and are therefore less toxic.
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Hg2+ does not bind tightly enough to the carboxylate groups of natural organic acids (natural chelators like citrate) for its toxicity to be prevented.
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Chelating agents, like EDTA, which can normally be deployed to inhibit the toxic effect of heavy metals like lead, have no inhibitory effect on the toxicity of mercury and may even increase it. Other chelating agents (DMPS and DMSA) inhibit the toxic effect of cadmium and lead ions, but not Hg2+. DMPS, DMSA or natural chelators like vitamin C, glutathione or alpha-lipoic acid are not able to remove mercury from nervous tissues. And DMPS or DMSA may even increase the inhibitory activity of mercurous and cadmium ions (Hg2+ and Cd2+) on enzymes but not of lead ions (Pb2+). Furthermore, the use of DMPS in animals led to an increase of mercury concentrations in the spinal cord.
Mercury in fish and other sources
The toxicity of methyl mercury which is bound to cysteine in fish seems to be far lower - approximately 1/20th - the methyl mercury compounds usually used in experiments.
Furthermore, marine fish represent a significant source of selenium and essential omega-3-fatty acids, which are known to protect effectively against mercury toxicity. Nevertheless, methyl mercury chloride, which proved to be more toxic than methyl mercury in fish, showed less neurotoxicity for the growing nervous system in vivo than mercury vapour.
Investigations by Drasch et al. show similar correlations when comparing the population of a gold mining area which was exposed to mercury vapour to a control group which was mostly exposed to methyl mercury from fish consumption. Those exposed to the mercury vapour showed significantly more neurological symptoms than the control group, despite their mercury levels in hair and plasma being higher compared to the individuals exposed to mercury vapour.
Another study also suggests that methyl mercury from fish is less toxic than that derived from the iatrogenic sources of dental amalgam and the vaccine preservative, thimerasol. Here, in contrast to the numbers of dental amalgam fillings in the mothers, no correlation between maternal fish consumption during pregnancy and the risk of autism for their children was found.
Some scientists argue that results gained from animal or in vitro cell testing cannot be extrapolated to the human body. However, in contrast to test animals in experiments, humans are exposed to many toxins simultaneously, thus the effects are additive or even highly synergistic. Such that the dose of mercury and the dose of lead that kill 1% of laboratory animals, when combined resulted in the death of all the experimental animals.
In this context, humans are estimated to have more mercury and between 10-1,000-times more lead in their body tissues than ancient humans. The addition of substances such as aluminium hydroxide or thimerasol (often in vaccines), antibiotics and the male hormone, testosterone, all increase the toxicity of mercury. The synergistic toxicity of testosterone with mercury may explain the observation that many more males than females suffer from autism or amyotrophic lateral sclerosis (ALS).
The adverse health effects of mercury
The most frequently reported symptoms of mercury toxicity due to amalgam fillings are:
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Chronic fatigue
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Headaches and migraines
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Increased susceptibility to infections
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Muscle pain
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Lack of concentration and poor memory
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Digestive disorders
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Sleeping disorders
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Joint pain
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Depression and mood disorders
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Heart sensations
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General dysregulation of body systems and many more.
In addition to these symptoms, Dr Mutter addresses the causative role of mercury in the following conditions:
Heart diseases Mercury may be the unseen cause of hypertension and myocardial infarction. Significant mercury accumulation (22,000 times higher than controls) has been found in heart tissues with a form of heart insufficiency.
Kidney disease The SCENIHR report cites several studies conducted mostly by dentists to justify their conclusion that "there is no evidence that dental amalgam fillings affect kidney function in humans". However, many other animal and human studies suggest that there is more kidney damage in subjects exposed to amalgam fillings than those without and that this first appears in children after only 5 years of amalgam exposure.
Autoimmune disorders Constant low-dose exposure to mercury from dental amalgam has been considered a possible cause for certain autoimmune diseases such as multiple sclerosis, rheumatoid arthritis or systemic lupus erythematosus (SLE). These effects occur with exposure below mercury safety limits. Recent research has shown that mercury and ethyl mercury have the ability to inhibit phagocytosis of immune cells at very low levels showing that even low levels of exposure can disrupt the immune system of all age groups.
Cancer Mercury from dental amalgam fillings has been shown to cause DNA damage in human blood cells and even at low levels, inorganic mercury can lead to significant DNA damage in human tissue cells and lymphocytes. These effects, which can trigger cancer, have been found with mercury levels below those normally causing cytotoxicity and cell death. Furthermore, aberrations of chromosomes can be provoked by amalgam in cell cultures.
Individuals with amalgam fillings show significantly increased oxidative stress in saliva and blood and this correlates with the number of amalgam fillings. Mercury levels normally seen in tissues of individuals with amalgam fillings lead to increased oxidative stress and reduction of glutathione levels, thus inducing cellular damage. Significantly elevated mercury levels have also been observed in breast cancer tissues.
Mercury deposited in the tissue is mostly bound to selenium, which means that the selenium is no longer available for use in the body. Therefore, amalgam may aggravate a latent deficiency of selenium, particularly in countries with a suboptimal selenium supply such as central Europe.
Infertility The SCENIHR report stated that "There is no evidence of any association between amalgam restorations and either male or female fertility or obstetric parameters". As a proof of this statement, the SCENIHR cited just one study, which examined semen in men. However, other studies especially in women show the opposite with female dental assistants showing a higher rate of infertility; women with more amalgam fillings or increased mercury levels in urine (measured after mobilisation with DMPS) demonstrating a higher incidence of infertility and heavy metal detoxification leading to spontaneous pregnancies in many of the 'infertile' patients. Exposure to mercury also leads to decreased male fertility.
Adverse health effects in dental staff
In relation to dental staff and dentists, the SCENIHR report states that "the incidence of reported adverse effects is very low".
However, a simple literature research reveals the opposite - that dental workers exhibit significant adverse effects. In some studies, the clinical outcome was not correlated with mercury levels in urine or blood, leading some authors to falsely conclude that mercury was therefore not the cause of the adverse effects. As stated above, urine and/or blood mercury levels do not correlate with tissue levels and so this is unscientific.
In 2007, Lindbohm et al. found double the risk for miscarriage in those occupationally exposed to mercury and this effect was stronger than that for exposure to acrylate compounds, disinfectants or organic solvents. Even 30 years after cessation of mercury exposure, dental nurses showed significant adverse health effects.
In spite of the fact that 85% of the dentists and dental technicians tested showed mercury related toxicities in both behaviour and physiological parameters, and 15% showed an increase of mercury induced neurological deficits with polymorphism of the CPOX4 gene, organised dentistry and SCENIHR still maintain that amalgams do not cause any significant medical problems because the urine and blood levels are below safety limits.
Further resources
Click the link for the full length original article by Joachim Mutter.
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