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Mercury Dental Amalgams - Analyzing the Debate
Revised May 2001
Note: The information on this
website is not a substitute for
diagnosis and treatment by a qualified, licensed professional.
The Evidence Against Mercury
Still, the scientific research proving mercury's toxicity has been piling up for years. And while a diagnosis itself may be elusive, the realities of mercury poisoning are hard to ignore when study after study shows that the mercury released from dental amalgams can wreak havoc on the body.
What follows is a description of various studies and reports that have explored the link between mercury amalgams and health disorders. As a body of work, these reports offer a comprehensive view of mercury's ability to enter the body and cause serious damage to physical and mental functioning:
The mechanism of mercury leaching.
According to organized dentistry, amalgams do not pose a long-term threat because the mercury becomes inert after a filling has set for several days. But a number of studies prove that mercury continues to leach from fillings due to the ongoing deterioration of the amalgam.
A variety of factors contribute to the corrosion of fillings, including the physical stress of chewing, the acidity and temperature of foods and beverages and the electromagnetic potential of other metals in the mouth. Dental amalgam contains not only mercury (52% by weight), but also silver, tin, copper and zinc. Crowns and bridges may contain these elements as well as aluminum, beryllium, gold, iridium and nickel.(46) Even the simple act of brushing your teeth can release mercury from amalgam, according to a 1985 report by J.E. Patterson.(47)
In a 1983 study, Hakon Hero and other researchers at the Scandinavian Institute of Dental Materials stated: Amalgam restorations tend to deteriorate at their margins after some time in service. The mechanism by which the degradation takes place is not fully understood. However, both electrochemical corrosion and particle release must be expected to occur.(48)
Indeed, microgram amounts of mercury leach from fillings daily. Researchers generally agree that each surface of a dental filling (an amalgam can consist of several layers) leaches one microgram of mercury per day.(49)
Consider the results of in vitro experiments that measured mercury leakage: When amalgam pieces weighing one gram were sealed in a glass tube for less than a month, they gave off up to 30 milligrams of mercury in total. That's about 1 milligram (1,000 micrograms) of mercury per day.(50)
In another experiment, researchers tested sterile water containing a one square centimeter piece of amalgam for two years. (One square centimeter is the size of an average dental filling.) The water was changed each day and tested for mercury content. The average daily release was 43 micrograms plus or minus 2.(51)
To follow through on the logic, consider that an amalgam has an initial weight of about one gram, and that mercury comprises about half of that weight, or 500,000 micrograms. If the amalgam corrodes by 50% over its 10-year life, then half of the mercury it initially contains -or 250,000 micrograms - has vanished.(52) And many studies have shown that the mercury content of some five- to 10-yearold fillings is indeed reduced to only 25 to 35%.(53)
Looking at this from an environmental point of view provides yet another chilling perspective on the amalgam issue. Wastewater from dental offices is a significant source of environmental mercury pollution. A study of Danish dental clinics with and without mercury separators found that clinics with separators released a mean value of 35 mg mercury per day. Clinics without separators released a mean value of 270 mg per day. It was concluded that a significant amount of mercury is released with the waste water from dental clinics. Several hundred grams of mercury per clinic may be discharged annually with the waste water. Installation of efficient amalgam separators may reduce the Hg outlet markedly, the authors conclude.(54)
Very few dental offices in the United States have amalgam separators. Taking the mean daily level of 270 milligrams times 200 (working) days per year yields an annual value of 54 grams of Hg per dental office per year. Utilizing a conservative figure of 100,000 dental offices in the United States, a total of 5400 kilograms (12,172 pounds) of mercury exits U.S. dental offices in waste water each year.(55)
One source reports that the total discharge into sewers from dental amalgam at individual homes and businesses is even more than at dental offices, since the average person with amalgam fillings excretes in body waste approximately 100 micrograms per day of mercury.(56) This has also been confirmed by medical labs such as Doctors Data Lab in Chicago and Biospectron in Sweden which do thousands of stool tests per year and is consistent with studies measuring levels in residental sewers by municipalities.(57) In the U.S. this would amount to approximately 7300 kilograms per year into sewers or over 8 tons per year.
In 1995 a Swedish scientist estimated the urinary and fecal excretion rates of mercury from dental amalgam fillings by the entire population of Sweden. He estimates that the average Swede has about 11 grams of mercury in their mouth, and that the country's 8 million citizens excrete about 100 kilograms of mercury into the environment every year.(58) Thus the amount of mercury being excreted from dental amalgam is more than enough to cause dangerous levels of mercury in fish in most streams into which sewers empty.
Other studies have analyzed the expired air of humans to determine how much mercury leaches from amalgams. In a 1985 study by Drs. Vimy and Lorscheider of the University of Calgary (Canada), 35 subjects with amalgams chewed gum for 10 minutes and released "quite substantial" amounts of mercury vapor into intra-oral air, about six times more vapor during chewing than before. Meanwhile, the intra-oral air of control subjects contained insignificant levels of mercury vapor, and the act of chewing did not alter those levels.
The researchers concluded: "The results demonstrate that the amount of elemental mercury released from dental amalgam exceeds or comprises a major percentage of internationally accepted threshold limit values for environmental mercury exposure. It is concluded that dental amalgam mercury makes a major contribution to total daily dosage."(59)
This study confirmed the findings of a similar experiment conducted in 1981 by C.W. Svare at the University of Iowa College of Dentistry and Environmental Chemistry. When researchers analyzed the mercury content in the expired air of 40 people with amalgams and eight without fillings, those with amalgams released 15.6 times more mercury vapor after chewing, while the expired air of the other subjects remained unchanged.(60)
In a study conducted in Germany in 1996, researchers found that amalgam carriers who chewed gum had urinary mercury levels twice that of controls with similar mercury burden who didn't chew gum.(61) The more you chew, the more mercury is released.
A 1997 Russian study found that emission of mercury vapors in the oral cavity increased with the number of fillings. According to these researchers, the concentration of mercury in the oral cavity depends primarily on the number of amalgam fillings and less so on the fillings' length of service.(62)
"The important point to remember is that mercury vapor, ions and abraded particles are escaping and being inhaled and swallowed as well as being absorbed by the oral and nasal mucosa continuously during the lifetime of an amalgam filling."(63)
Amalgam fillings are the main source of mercury exposure.
Amalgam apologists, in their efforts to minimize the dangers of amalgam, often assert that mercury amalgam is only one among many sources human exposure to mercury toxicity. For example, DW Jones, in a comment published in the Journal of the Canadian Dental Association, asserts that "the uptake of food-related organic mercury is six times higher than the uptake of mercury from amalgam; moreover, food-related mercury is significantly more toxic."(64)
However, numerous studies support the finding that amalgam fillings are the main source of mercury exposure in the general population. Perhaps the earliest of these is the 1991 report, "Environmental Health Criteria 118" produced by the World Health Organization in conjunction with the United Nations Environment Programme and the International Labor Organization. This report states very explicitly that mercury dental fillings are the principal source of mercury and mercuric compound intake and retention among the general population not occupationally exposed to mercury. The WHO report sets the average daily intake of mercury from amalgams at 3.8-21 micrograms per day.
A 1995 review by Drs. Lorscheider and Vimy and Anne O. Summers, a biochemist, concludes that " Medical research has demonstrated that [mercury from dental amalgams] is continuously released as vapor into mouth air. Animal and human experiments demonstrate that the uptake, tissue distribution, and excretion of amalgam mercury is significant, and that dental amalgam is the major contributing source to mercury body burden in humans."(65)
A 1994 study of patients undergoing total amalgam removal found that exposure from amalgam fillings exceeds exposure from food, air and beverages.(66) A 1992 experiment involving volunteers with and without amalgam fillings concluded that two-thirds of the mercury excreted in the urine of those with dental amalgams is derived originally from the mercury vapor released from their amalgams.(67)
Once an amalgam releases mercury vapor, the inhaled fumes can travel throughout the body and into the brain. As a result, it is absorbed into body tissues, oxidized to ionic Hg, and finally covalently bound to cell proteins.(68) The mercury fumes also settle on the mucous membrane of the nasal cavity, an especially dangerous location since the mercury is then transported directly to the pituitary gland and, again, the brain.(69)
A study released in 1989 followed the route of mercury vapor in the bodies of five pregnant sheep. Dr. Vimy, a consultant to the World Health Organization, placed amalgams in the sheeps' molars during the middle of their pregnancy. The researchers then used a radioactive isotope to isolate the amalgam mercury from other sources and trace its course. They noted the following effects after the amalgam placement:
Day 3: Mercury build-up was evident in the maternal and fetal blood, the amniotic fluid and the maternal urine and feces.
Day 16: Maternal mercury levels were highest in the kidneys, liver, gastrointestinal tract and thyroid. Fetal levels peaked in the pituitary gland, liver, kidneys and placental cotyledon.
Day 33: Most fetal tissues of the newborn sheep had higher mercury levels than did the maternal tissues, specifically in the liver, epiphysial bone, bone marrow, bile, blood and brain.
Day 73: Mercury levels in the mothers' tissues continued to rise in the kidneys, liver, parotid glands, lungs, pancreas, gastrointestinal tract, adrenal glands, pituitary gland, urine, bile, brain and thyroid gland.
Based on these results, the researchers concluded not only that the mercury released from fillings accumulates in maternal and fetal tissues, but also that "dental amalgam is most probably the major source of chronic mercury exposure in humans."(70)
Children are especially susceptible to the effects of mercury accumulation because their bodies are still developing. In 1994 German researchers discovered that children with amalgam fillings have four-fold higher urinary concentration of mercury and creatinine than children without amalgams. The researchers also confirmed the correlation between the number and extent of amalgam fillings and the urinary mercury concentration.(71)
Once mothers realize the fillings in their teeth damage the development of their babies' brains while they're in the womb, and once these women understand this damage can result in low IQ, learning and behavioral problems after birth, then we'll see a public outcry against the use of mercury amalgam," says Charles Williamson, MD, co-director of the Toxic Studies Institute in Boca Raton, FL. He envisions something like the backlash against tobacco or drunk driving.(72)
"Mercury vapor is toxic, period," Williamson continues. "The fetus is especially vulnerable to that toxicity, which can cause brain damage. Mercury vapor can cause learning disabilities, autism, and attention deficit disorder in unborn children. How will parents feel when they grasp that?"(73)
"One of these days there's going to be a mammoth lawsuit about mercury fillings, similar to one that's already been filed in Canada. It could be bigger than what we've seen over tobacco. It's going to hit people like a Mack truck when they realize that putting mercury amalgam fillings in their teeth amounts to putting poison in their mouths."(74)
Placement and removal of "silver" tooth fillings in pregnant and lactating humans will subject the fetus and neonate to unnecessary risk of Hg exposure, according to parallel 1997 studies conducted on sheep and humans. The authors conclude that Hg originating from maternal amalgam tooth fillings transfers across the placenta to the fetus, across the mammary gland into milk ingested by the newborn, and ultimately into neonatal body tissues. Results from the animal studies showed that, during pregnancy, a primary fetal site of amalgam Hg concentration is the liver, and, after delivery, the neonatal lamb kidney receives additional amalgam Hg from mother's milk. In lactating women with aged amalgam fillings, increased Hg excretion in breast milk and urine correlated with the number of fillings or Hg vapor concentration levels in mouth air.(75)
Dr. Williamson echoes these findings. The pituitary gland is a critical element in the transport of mercury vapor from the mouth to the brain in adults and children who have mercury fillings. Mercury vapor has a particular affinity for the pituitary gland, which is just 2 centimeters away from the oral cavity, just the other side of the cribiform plate-a light spongy bone in the roof of the nose, between the eyes. Mercury penetrates the cribiform plate via "axonal transport." "It goes right up the neurons," Williamson explains.(76)
Dr. Williamson applauds the action of the American Academy of Pediatrics in calling for a moratorium on the use of Thimerosal mercury in vaccines, and those gynecologists who warn their patients not to eat fish during pregnancy. But, he points out, those measures merely scratch the surface of the problem, because 87% of the body burden of mercury comes from amalgam fillings, which release mercury vapor into the body 24 hours a day.(77)
Mercury accumulates in human tissues, leading to increased oxidative damage, mitochondrial dysfunction, and cell death. Dr. Williamson emphasizes mercury's effect on the fetal pituitary gland-which affects development of the endocrine, immune, and reproductive systems. "The fetal pituitary gland concentrates mercury." Mercury, Williamson observes, decreases transport to the fetus of oxygen and essential nutrients, including amino acids, glucose, magnesium, zinc and vitamin B12. It also depresses the enzyme Isocitric Dehydrogenase. This causes reduced iron uptake and hypothyroidism, learning disabilities, and reduction in IQ. Mercury exposure affects levels of nerve growth factor in the brain, impairs astrocyte function and causes brain developmental imbalances.(78)
Williamson says all these problems are compounded when a pregnant woman has amalgam fillings placed in her mouth or removed during the first trimester of pregnancy. "The level of mercury in the tissue of the fetus, newborn, and young children is directly proportional to the number of amalgam surfaces in the mother's mouth. Inorganic mercury methylated in the mouth by microorganisms to organic mercury is the most acutely neurotoxic form."(79)
Mercury toxicity causes a variety of reproductive disorders, including sterility or reduced fertility and spontaneous abortions. Sperm count and sperm motility in males can also be significantly reduced, according to Dr. Williamson.
"The effect of mercury vapors on the pituitary gland produces hormonal disruption and menstrual cycle disorders. When amalgam fillings are removed, menstrual cycles normalize and fertility increases."(80)
The formation of methylmercury.
Common organisms of the mouth and intestines can convert elemental mercury into methylmercury, an organic form of the metal that attacks the nervous and immune systems, the intestinal functioning and the allergy-triggering mechanism.35, 36 Methylmercury can be particularly devastating: It is absorbed through the intestinal wall 45 times more rapidly than mercury and is retained in the body longer.(81)
Methylmercury is 1,000 times more potent in causing genetic damage than colchicine, the next most powerful agent known, according to Swedish professor Claes Ramel. In experiments with fruit flies and onion root cells, extremely low doses of Methylmercury - 0.1 ppm or less -inhibited mitosis and caused chromosome breakage. Sublethal doses also decreased the fertility rate in mice, and increased the rates of litter resorption and stillborn fetuses in pregnant mice.(82)
Methylmercury can cause harm to every part of the body. It leads to bleeding and bone loss, a loss of muscle coordination, impaired vision and sense of smell, and kidney and glandular dysfunction. It is 100 times more toxic to the nervous system than is elemental mercury.(83) Methylmercury can permanently damage the brain and nervous system, in fact. Following a large exposure, high levels of methylmercury can lodge in the brain for 10 years or more.(84) Unlike elemental mercury, which touches the outside of a cell and hinders its ability to interact with others, methylmercury actually penetrates the cell. That means it can disrupt the cell's metabolism, break its DNA and, with the addition of a few more mercury molecules, kill the cell.(85)
Methylmercury even passes the bloodbrain and placental barriers, says Dr. Huggins. "There is virtually no barrier in the body to methylmercury. It can go to every cell in the body."(86) When it passes the placental barrier, it accumulates in the fetal brain and blood, thereby increasing the fetus's level of red blood cells to 30% above that of the mother.(87)
Indeed, pregnant women who show no signs of mercury poisoning can give birth to a child with neurological disorders caused by either mercury or methylmercury.(88) The effects of mercury exposure on children include: extensive changes to the brain that affect the entire cortex, including the frontal lobe; a 26% to 55% reduction in brain weight; and a heavy loss of neurons. In cases where the neuron loss exceeded 50%, decortication syndrome developed.(89)
Mercury's accumulation in the brain.
The link between dental amalgams and the presence of mercury in brain tissue was established in a 1987 study conducted by Dr. David Eggleston of California in conjunction with Dr. Magnus Nylander of Sweden. The study found a direct correlation between the number of occlusal molars and the amount of mercury accumulated in the brains of 83 cadavers.(90) The subjects with five or more amalgams had an average of three times more mercury in the brain than those with no amalgams.(91) Likewise, autopsies performed at the Karolinska Institute in Sweden, whose board of governors selects the recipient of the Nobel Prize for Medicine, found that people with amalgams had three times more mercury in the brain and nine times more in the kidneys than those with no amalgams. The parts of the brain most vulnerable to mercury amalgam accumulation are the occipital lobe cortex, the cerebellar cortex, and the semilunar ganglion, according to the study.(92)
One of the nation's leading toxicologists, Dr. Louis Chang, also has found a direct connection between dental amalgams and mercury concentrations in the brain. "Mercury levels tend to be higher in those people that have the amalgams, and mercury levels increase as the number of amalgams increases," reports Chang, director of interdisciplinary toxicology and experimental pathology and a professor of pathology, pharmacology and toxicology at the University of Arkansas.(93)
Chang's observation is borne out by recent research. In 1999 Croatian researchers studied two experimental groups of rats, one with amalgam fillings placed in their teeth and another who were fed an amalgam supplemented diet. The results showed significantly higher concentrations of mercury in the kidneys and brains of both exposed groups compared to controls. Even after two months of exposure to mercury, brain mercury concentration in rats with amalgam fillings was 8 times higher than in the control and two times higher than in rats who ate amalgam-supplemented food.(94) The study clearly elucidates the importance of the nose-brain route in mercury assimilation. The inhalation of mercury vapor from amalgam fillings delivers mercury to the brain even more effectively than eating it. In a 1996 study conducted at the University of Tubingen in Germany, autopsy of 55 subjects revealed a statistically significant correlation exists between the number of dental amalgam fillings and the mercury concentration in the occipital lobe cortex.(95)
The link with neurological disorders.
Occupational and environmental exposure to mercury is known to cause neurological disorders, including syndromes that mimic multiple sclerosis and amyotropic lateral sclerosis, says Dr. Douglas Swartzendruber, chairman of the department of biology at the University of Colorado at Colorado Springs. As a result, it's reasonable to consider that the mercury from amalgam may have a similar effect.
"Much of the controversy concerning mercury is the possible relationship between mercury released from dental amalgams and multiple sclerosis," states Dr. Swartzendruber. While the controversy has not yet been addressed by a controlled clinical trial, he says, several studies provide evidence of a causal relationship. In one such study, he explains, researcher E. Baasch demonstrated in great detail that "facts concerning the geographical and age distribution, pathological development and symptomatology of multiple sclerosis are all consistent with amalgams as the primary cause of the disease."(96)
A 1994 paper by Siblerud and Keinholz investigates the hypothesis that mercury from silver dental fillings may be related to multiple sclerosis. It compares blood findings between MS subjects who had their amalgams removed to MS subjects with amalgams. MS subjects with amalgams were found to have significantly lower levels of red blood cells, hemoglobin and hematocrit compared to MS subjects with amalgam removal. Thyroxine levels were also significantly lower in the MS amalgam group and they had significantly lower levels of total T Lymphocytes and T-8 (CD8) suppressor cells. The MS amalgam group had significantly higher blood urea nitrogen and lower serum IgG. Hair mercury was significantly higher in the MS subjects compared to the non-MS control group. A health questionnaire found that MS subjects with amalgams had significantly more (33.7%) exacerbations during the past 12 months compared to the MS volunteers with amalgam removal.(97)
A 1998 study found a "suggestive elevated risk" for multiple sclerosis among individuals who had a large number of amalgams for a long period of time.(98) In a retrospective study conducted in England the following year, the odds of being a MS case increased multiplicatively by for every additional unit of dental caries. This represents a 21% increase in risk of MS in relation to dental caries.(99)
Of multiple sclerosis, Dr. Phillips says, "My training with Dr. Yoshiaki Omura has led me to know that disease deeply. I don't treat the disease, but I work with doctors who do. And Dr. Omura in his research has found that every MS patient has mercury and lead in their brain and spinal cord along with cytomegalovirus and borellia bergdorferi."(100) Borellia is the spirochete that causes Lyme disease.
Alzheimer's disease (AD) is a common neurodegenerative disorder that leads to dementia and death. About a decade ago scientists began to document a connection between mercury and Alzheimer's disease. A group led by Dr. William Markesbery, Director of the Sanders Brown Center on Aging at the University of Kentucky, and Dr. William Ehmann autopsied the brains of Alzheimer's patients revealing that the Alzheimer's brain tissue had about double the concentration of mercury as compared to brain tissues from patients who died of all other causes.(101) They also discovered that in Alzheimer's patients' brains, the nucleus basalis of Meynert, a brain areas that transmits memories and sensations to higher areas of the brain, contained almost four times as much mercury as controls.(102)
More recently, this team studied concentration of mercury and four other trace elements (selenium, iron, rubidium, and zinc) in the pituitary glands of deceased Alzheimer's patients. The pituitary gland has been established as a good predictor of environmental mercury exposure, as opposed to exposure via mercury amalgam fillings. The study found no increased concentration of mercury in the pituitary, indicating that excessive mercury concentrations in the brains of Alzheimer's patients are not of environmental origin.(103) If the mercury is not of environmental origin, where did it come from?
Another team at the Department of Psychiatry of the University of Basel, Switzerland, investigated whether blood levels of the heavy metal mercury are increased in Alzheimer's disease. They measured blood mercury concentrations in 33 Alzheimer's, and compared them to 45 age-matched control patients with major depression, as well as to an additional control group of 65 patients with various non-psychiatric disorders. Blood mercury levels were more than two-fold higher in Alzheimer's patients as compared to both control groups. In early onset AD patients, blood mercury levels were almost three-fold higher as compared to controls.(104)
A 1995 animal study by Lorscheider, Vimy, and Summers adds further credibility to the Alzheimer's - mercury connection. It revealed that mercury vapor interacts with brain tubulin and disassembles microtubules that maintain neurite structure. Thus ionic mercury can alter a neurochemical reaction involved with maintaining neuron membrane structure. This results in the formation of "neurofibrillary tangles," which are a characteristic feature of brain tissue from Alzheimer's patients.(105) A later experiment by Lorscheider and Vimy in collaboration with Dr. Boyd Haley at the University of Kentucky's Lucille Markey Cancer Center builds on this discovery. Rats were exposed to carefully controlled dosages of mercury vapor mimicking the levels found in the mouths of people with a high number of amalgam fillings. The rats deteriorated very quickly, developing brain lesions identical to those found in human Alzheimer's disease patients.(106)
Boyd Haley, one of the principal researchers, commented, "The results of this experiment are terrifying. I'm getting the rest of my mercury fillings taken out right now, and I've asked my wife to have hers replaced, too."(107)
While these dedicated researchers were striving to uncover the secrets of a destructive and much feared disease, the American Dental Association published and widely publicized a study of its own. Clearly, the ADA was concerned about the growing public perception that there is a connection between Alzheimer's disease and the mercury in our mouths.
In a study conducted at the College of Dentistry at the University of Kentucky, researchers led by Dr. Stanley R. Saxe, a retired professor of periodontics and geriatric dentistry, studied 68 subjects with AD and 33 control subjects without AD to determine Hg levels in multiple brain regions at autopsy and to ascertain the subjects' dental amalgam status and history. The authors conducted dental amalgam assessments during the lives of the majority of subjects and in some subjects at the time of autopsy only. They also determined three dental amalgam index scores--Event (placement, repair or removal of amalgam), Location and Time In Mouth--in addition to the numbers of and surface area of occlusal amalgam restorations. They determined mercury levels in multiple brain regions and performed full neuropathologic evaluations to confirm the normal status of the brain or the presence of AD. The results? They found no significant association of Alzheimer's disease with number, surface area, or history of having dental amalgams. Furthermore, the team found no differences in brain levels of mercury between subjects with Alzheimer's disease and controls.(108)
There is nothing particularly surprising about the results of this study. Studies that fail to show any positive result are the rule, rather than the exception in science. It is important to understand, however, that the failure to find a positive result does not prove that there is no relationship between dental mercury and Alzheimer's disease. It merely shows that the phenomenon in question was not observable under the conditions of the experiment in question. All responsible scientists are aware of this fact.
Except perhaps Stanley R. Saxe, DMD, the lead researcher for the ADA Alzheimer's study. In a story distributed nationally by PR Newswire in February 5, 1999, Saxe put the following spin on the results of his team's research: "This study demonstrates that dental amalgam is not a major public health risk factor for Alzheimer's disease….This is the first thorough clinical pathological correlative study of humans to show that mercury in dental amalgam restorations does not appear to be a neurotoxic factor in the development of Alzheimer's disease."(109) Saxe's statements appeared in media all over the country.
One wonders how some of the more responsible scientists who participated in this research-including Drs. Markesbery and Ehmann, whose own discovery of the mercury-Alzheimer's connection was cited at the beginning of this section-feel about Dr. Saxe's totally unscientific pronouncements. How is it, we must ask ourselves, that this "conclusive" study failed to find differences in brain levels of mercury between subjects with Alzheimer's disease and controls, a relationship which had been demonstrated in numerous earlier studies? (110-115)
The Ziffs' commentary on the Saxe study, in Dentistry without Mercury, reveals some of the contradictions inherent in Saxe's position.(116) They cite an earlier study of a population of elderly nuns in which Saxe found no correlation between mercury amalgam and indicators of Alzheimer's disease.(117) That study, the Ziff's point out, compared a group of nuns with existing amalgam molar fillings to a control group of nuns with no amalgam in their remaining molars. The nuns in the study ranged in age from 74 to 102. The problem is that the control nuns only had an average of three out of a possible sixteen molars remaining (twenty if you count wisdom teeth). Dr. Saxe apparently failed to consider that the molars that the control nuns had lost very likely did contain amalgam fillings (all the nuns had similar diet and lifestyle factors) and that the mercury levels remaining in those nuns' tissues after a lifetime of amalgam exposure would be no different from that of the nuns with existing amalgams.(118) In other words, Saxe failed to establish a valid control group. He compared two groups with similar histories of exposure to mercury from amalgam fillings and found that their status with respect to Alzheimer's disease was similar. This is junk science.
There was a similar methodological flaw in the later study, the one that the ADA publicized so widely. Here, tissue studies at autopsy from a group of 68 nuns with Alzheimer's disease were compared to a group of 33 nuns without Alzheimer's. But there was no control group who had never been exposed to mercury amalgam. That, say the Ziffs, is a "critical aspect of studies of this type." (119) The lack of this crucial link in the chain of discovery renders the results questionable, if not worthless. This is the research equivalent of the old shell game. "Now you see it, now you don't."
This is a classic example of the doublespeak and denial employed by the American Dental Association and its supporters in their dogged attempt to mislead the public about the dangers of mercury amalgam fillings. They ignore all existing research which strongly suggests, but does not prove, a link between Alzheimer's and amalgam. And with one study, they attempt to sweep the whole issue under the rug. The ADA is more interested in conducting propaganda campaigns than it is in discovering the truth. Their dogged defense of amalgam is nothing but smoke and mirrors.
But that's not the end of the story. In 2000, researchers at the Neurobiology Laboratory, Psychiatric University Hospital in Basel, Switzerland using demonstrated that neuroblastoma cells exposed to mercury show an increase in production of amyloid protein. That's the stuff that makes up the amyloid plaques that are usually found in the brain tissues when Alzheimer's patients are autopsied.(120)
More recently, Dr. Lorscheider, whose University of Calgary study of mercury's effect on neurite structure is cited above, has produced direct visual evidence that clarifies the precise site and mode of action of mercury ions in causing Alzheimer's-like neurodegeneration. Lorschieder and his research team hypothesized that the growth cones from animal species could be highly susceptible to mercury ions.(121) Growth cones are the structures at the outer ends of neurites where the protein synthesis takes place. Protein synthesis is essential to cell growth and vitality. To test their hypothesis, the team cultured neurons from the central ring ganglia of a snail's brain. Following neurite outgrowth, metal chloride solution of mercury, aluminum, lead, cadmium, and manganese was applied directly onto individual growth cones. Time-lapse images with inverted microscopy were acquired prior to, during, and after the metal ion exposure. The research demonstrates that Hg ions markedly disrupted membrane structure and linear growth rates of the neurites in 77% of all nerve growth cones. When growth cones were stained with antibodies specific for both tubulin and actin, it was the tubulin/microtubule structure that disintegrated following Hg exposure. Moreover, some of the disintegrated neurites were also observed to form neurofibrillary aggregates.
In a related experiment to determine the growth suppressive effects of Hg ions on neuronal sprouting, cells were cultured either in the presence or absence of Hg ions. We found that in the presence of Hg ions, neuronal bodies failed to sprout, whereas other metallic ions did not effect growth patterns of cultured snail brain cells. The authors conclude that this visual evidence and previous biochemical data strongly implicate mercury as a potential etiological factor in neurodegeneration as observed in Alzheimer's disease.(122)
We can expect considerable backlash from the spokespeople of the ADA as they try to deny the results of this study. Lorscheider's videos are quite unequivocal, however. You can actually see the neurites dying off as they encounter the mercury.
The effects on immune functioning.
Not everyone who has dental amalgams will develop highly visible reactions that demand medical attention. But even in cases where no easily identifiable disease occurs, mercury will diminish the effectiveness of the immune system. As the accumulation of mercury depletes a person's ability to resist the slightest challenge, the patient reaches a "threshold" point at which he or she succumbs to an illness or disease that appears to be a minor final "cause."(123)
Mercury is considered to be a strong immune depressant because it alters the number of T-cells. The cells decrease in number when amalgams are placed in the mouth and increase when the fillings are removed.(124) The other metals contained in amalgam can affect the immune system as well. One recent study found the following immune reactions in 1,000 subjects: 90% to mercury; 87% to copper; 83% to zinc; 56% to tin; and 45% to silver.(125)
In his study of mercury amalgam's effect on immunomodulatory reactions, Dr. Swartzendruber of the University of Colorado found that intra-oral heavy metals altered the quantity and quality of lymphocyte subset distributions. While functional analyses were not performed on the altered lymphocytes, he states, "The consistent finding of recurrent and intercurrent infections strongly suggests that the symptomatic patients are immuno-compromised." The reactive patients also experienced a serious loss of mononuclear cell viability.
More recently, these findings were confirmed by animal experiments done in Sweden. In the 1994 study, mice were implanted in the peritoneal cavity with 8-100 mg silver amalgam or silver alloy for 10 weeks or 6 months. The researchers repeat an unsettling litany of immune effects: "Chronic hyperimmunoglobulinemia, serum IgG autoantibodies targeting the nuclear protein fibrillarin, and systemic immunecomplex deposits developed in a time- and dose-dependent manner after implantation of amalgam or alloy. Splenocytes from mice implanted with amalgam or alloy showed an increased expression of class II molecules. The functional capacity of T and B spleen cells was affected in a dose-dependent way: 10 weeks of low-dose and 6 months of high-dose amalgam implantation strongly increased mitogen-induced T and B cell proliferation, whereas 10 weeks of high-dose implantation decreased the proliferation. Not only mercury but also silver accumulated in the spleen and kidneys after amalgam implantation."(126)
This means that dental amalgam implantation in genetically sensitive mice causes chronic stimulation of the immune system with induction of systemic autoimmunity. The authors thus conclude that under appropriate conditions of genetic susceptibility and adequate body burden, heavy metal exposure from dental amalgam may contribute to human immunological aberrations, which could lead to overt autoimmunity. This research is strongly suggestive of a link between mercury amalgam and autoimmune disorders.(127)
Given these results, says Dr. Swartzendruber, amalgam's impact on immunity should be carefully studied. "It is possible that such individuals may also be susceptible to other systemic effects of heavy metal, particularly since in the rat it is clear that heavy metals can induce autoimmune disorders. Heavy metals should be carefully considered as possible etiological agents in human diseases thought to have an autoimmune component."(128)
The relationship to depression and other emotional disturbances.
Because mercury is so soluble, it can go through the roof of the mouth to within less than an inch of the posterior pituitary gland, which has much to do with our outlook on life. When these glands do not function properly, depression may result. As Dr. Huggins says, "It's not the stress that gets us; it's how we interpret the stress."(129)
Mercury intoxication also has been linked to mental symptoms such as psychasthenia, which affects one's ability to make trivial decisions, resolve doubts, resist compulsions or phobias and perform simple intellectual tasks. Other symptoms include a lack of self-confidence and extreme timidity; a self-effacement that can cause severe depression; moodiness, rage and anxiety; and an irrational fear of death. And in other cases, mercury exposure causes an extreme form of fatigue that overwhelms its victims and confines them to bed because they no longer have the physical and mental strength for everyday activities.(130)
General health problems - and particularly those related to mental health - were 45% greater in patients with amalgams in a study conducted by Dr. Robert Silberud of Colorado State University in 1988. Among the common symptoms were sudden unexplained anger, irritability, anxiety and depression. One year after 86 of the test subjects had their amalgams removed, 70% of the recorded symptoms had either decreased or disappeared.(131)
A more recent study by Siblerud and colleagues provides further evidence that mercury amalgam fillings may be a causative factor in depression, excessive anger, and anxiety. The researchers compared scores on the Beck Depression inventory for 25 women who had mercury amalgam fillings and for 23 women without amalgams. Women with amalgams had significantly higher scores and reported more symptoms of fatigue and insomnia. The women with amalgams had significantly higher mean scores on expressing anger without provocation and experiencing more intense angry feelings. The women without amalgams scored significantly higher on controlling anger. Anxiety scores showed the women with amalgams scored significantly less pleasant, satisfied, happy, secure, and steady, and had a more difficult time making decisions.(132)
A related finding by the same group of researchers suggests that people with amalgam fillings may be more likely to smoke cigarettes. This study reveals that people with amalgam fillings smoke more than people without amalgams, and speculates that nicotine has the effect of compensating for the decreased levels of serotonin, norepinephrine, and acetylcholine in the brain caused by mercury exposure.(133)
A more recent study conducted in Oslo, Norway's National Hospital reveals that self-referred patients with health complaints attributed to dental amalgam suffer multiple symptoms and frequently have mental disorders. The physical and mental symptomatology of 99 self-referred patients complaining of multiple somatic and mental symptoms attributed to dental amalgam fillings were compared with patients with known chronic medical disorders. The dental amalgam sample reported significantly more physical symptoms from all body regions. Self-reports suggested that 62% suffered from a chronic anxiety disorder (generalized anxiety disorder or panic). Forty-seven percent suffered from a major depression compared with 14% in the two clinical-comparison samples and none in the dental control sample. Symptoms suggesting somatization disorder were found in 29% of the dental amalgam sample compared with only one subject in the 272 comparison subjects. One third of the dental amalgam patients reported symptoms of chronic fatigue syndrome compared with none in the dental control sample and only 2 and 6%, respectively, in the two clinical comparison samples.(134)
A group of Swedish researchers investigated psychological aspects of 49 patients with oral lichenoid reactions (OLR) in contact with amalgam fillings and compared with an age- and sex-matched control group. Oral lichenoid reactions are lesions of the mucous lining of the mouth that are caused by amalgam fillings. Psychologic factors such as personality, psychologic functioning, and quality of life were determined by using the Karolinska Scales of Personality (KSP), an additional Personality Scale (PS), a PsychologicalFunctioning Scale (PFS), and a Quality of Life Scale (QLS). With regard to personality the OLR patients had significantly higher scores on the muscular tension and suspicion scales and significantly lower scores on the indirect aggression scale. In addition, the OLR patients were significantly more worried about their health and more helpful. With regard to psychologic functioning the OLR patients had significantly more sad thoughts, became dizzy more easily, found it harder to imagine themselves free from anxiety, and had more difficulty in concentrating. The results indicated that OLR patients had a tendency to be depressive.(135)
Similar findings in the hands of the American Dental Association take on a sinister twist. A June, 1999, article in the American Journal of Dentistry cites a study in which 89% of the patients with self-reported amalgam illness were found to have psychogenic disorders and another indicating that patients suffering from amalgam-related illness had "preneurotic reactive/defensive mechanisms that did not allow them to recognize aggressive and threatening situations which the control group would quickly and readily regard as potentially difficult to manage."(136) The authors warn their fellow dentists that such patients "may present at the dentist's office, either self-diagnosed or looking for a cause implicating mercury. In actuality, these patients may have symptoms of either medical problems or psychological disorders such as depression or anxiety."(137) In this report, appropriately subtitled "A status report for the American Journal of Dentistry," the ADA sends a crystal clear message to its members: watch out for patients who complain of amalgam-related symptoms. They are crazy! It is apparent that the ADA, which has turned a blind eye to the mounting evidence against mercury fillings, has also become blind to the suffering of dental patients.
Mercury's effects on dentists and dental personnel
The American Dental Association's obvious disregard for the suffering of people with amalgam-related illnesses is ironic, given the effect that amalgam has on the people who work with it every day: dentists and their staff. As early as 1987, a Swedish study conducted for the Occupational Health Program of the Harvard School of Public Health assessed whether suicide rates were higher among dentists than other college-educated professionals over the ten-year course of the study. Results show an elevated standardized mortality ratio for male dentists compared to other male academics. The authors conclude that there is a need to investigate further the mental health consequences of mercury exposure among dentists.(138) Related studies indicate that dentists may be more vulnerable to stress and consequent depression than members of other professions.(139) For example, a study of dentists in private practice in South Africa found that 10 percent had severe suicidal ideation.(140)
A 1995 study documented the behavioral effects of low level mercury exposure on dentists working with amalgam. Behavioral tests revealed significant urinary mercury dose-effects for poor mental concentration, emotional lability, somatosensory irritation, and mood scores as compared to a control group of non-amalgam dentists. The mean urinary concentration was 36 micrograms per liter, seven times higher than the mean level measured in a national sample of dentists. There was evidence of subtle preclinical changes in behavior associated with mercury exposure. Coproporphyrin, one of three urinary porphyrins altered by mercury exposure, was significantly associated with deficits in digit span and simple reaction time.(141)
A follow-up cross-study found that long term exposure to amalgam can make dentists' hands shaky, and this has a negative impact on the manual dexterity of dentists. Researchers found remarkable differences in psychomotor performance between the amalgam and non-amalgam dentists. The most significant associations were found for the Intentional Hand Steadiness Test. The authors warn that the IHST results should be carefully considered by dental professionals who rely on manual dexterity in restorative dentistry.(142) That would include any dentist who does fillings, root canals, or bridgework!
In a later study, the authors were able to make subtle distinctions among the effects of mercury at different tissue concentrations. They comprehensively assessed fine manual speed, accuracy, and coordination, measures of particular relevance for dental professionals who work with handheld tools. The results revealed that subtle preclinical effects found at very low levels of mercury (urinary levels of less than 4 micrograms per liter) exposure appear on a continuum with the far more severe clinical deficits. Behavioral responses typically increased with exposure in a fairly uniform manner, indicating a more general response. The pattern of results, comparable to findings previously reported among subjects with high urinary mercury concentrations (greater than 50 micrograms per liter of urine), presents convincing new evidence of adverse behavioral effects associated with low exposures within the range of that received by the general population.(143)
A 1992 study revealed evidence of reduced fertility among dental assistants who work with mercury. Women who prepared thirty or more amalgams per week and had three or more poor mercury hygiene factors were 50% less likely to conceive during a given menstrual cycle than unexposed women.(144)
Dr. Douglas J. Phillips, a dentist practicing biological dentistry in Palm Beach, Florida, describes his own struggle with mercury amalgam-related illness as follows: "I started my own practice in 1970 in Palm Beach, and I decided about two months later not to work with amalgam, not to put any amalgams in, because I knew there was something I didn't like about it. During those times we didn't wear gloves or masks, and I drilled out a lot of amalgam fillings, and I breathed it. And I was taking vitamins, minerals, chelating agents, and I thought that I was well covered. I thought that it was bouncing off me. Then in the early nineties I wasn't well at all, and I found out that in spite of all the things I had done for my health, I was extremely mercury toxic."(145)
Dr. Williamson of the Toxic Studies Institute sums it up this way: "If you pull up the carpets in a dental office, it's just bloated with mercury. When you see a 52-year-old dentist whose memory is in the 15th percentile, something's wrong there."(146)
The effects on kidney functioning.
The impairment of kidney functioning from mercury amalgam may be even more severe than previously thought, according to another study by Drs. Vimy, Lorscheider and others. Again, the researchers placed amalgams in the teeth of sheep (whose weight and chewing mechanism compare well with those of humans). Within 30 days, the sheep lost half of their kidney function, and beyond that point the functioning remained low. Meanwhile, the average amalgam lasts 8 to 10 years, allowing for extensive mercury exposure. (147, 148)
The effects on blood and bone cells.
Preliminary studies at Colorado University indicated that blood and bone cells may be highly sensitive to mercury. Researchers found that mercury in a ratio of less than 40 parts per billion was lethal to white blood cells. Another study found that mercury concentrations of less than 0.4 parts per million killed bone cells. Yet it is estimated that at least 700 times more mercury than this amount rests in the gum tissue next to amalgam fillings.(149)
A laboratory study published in 2000 by the Biomaterials Unit of the School of Dentistry at the University of Birmingham in England gives further support to those findings. Mercury released from Tytin, a mercury amalgam dental filling material, undermined the viability of primary periosteal and osteoblast cells in culture. The cells were grown from the parietal bones of 2-3 day old Albino Wistar rats and were exposed to the test materials for 1 or 6 days. The number of viable cells in each test group was determined, and the area of cell death around the test specimens was also measured. Mercury was the main element released from the dental amalgam followed by copper and silver. The viability of cultures containing Tytin was significantly lower than cultures with a gallium-based alloy and the controls.(150)
A study of cytotoxicological effects on animal tissues concluded that the level of mercury and copper in amalgam filling materials makes them significantly more cytotoxic than either of two amalgam alternatives.(151)
Antibiotic resistance is a serious public health issue. With the extensive use of antibiotics in modern medicine, some bacteria spontaneously undergo genetic alteration that makes them resistant to certain antibiotic drugs or classes of drugs. As a result, doctors may have to use higher doses of antibiotics, thus driving up the cost of treatment. Worse still, some antibiotics lose their effectiveness altogether, and doctors have a narrower choice of drugs to choose from in treating illness. In some cases, antibiotics fail altogether, and patients may die.
What does antibiotic resistance have to do with mercury amalgam? That is a question that no one ever asked until about ten years ago. In her studies of antibiotic resistance, microbiologist Anne Summers had long been aware that there was a high degree of mercury-resistance in human fecal bacteria. That meant that the bacteria in question had somehow been exposed to mercury and had developed resistance to the metal's toxic effects. This finding puzzled Summers. How had all these people been exposed to mercury? Summers refrained from publishing her findings, because they made no sense based on her current knowledge.(152) Then, in 1989 Summers came upon the pioneering work of Drs. Lorscheider and Vimy showing that amalgam fillings implanted in sheep's molars released toxic mercury that could be tracked all over the animals' bodies.(153) Summers began to suspect that the cause of the mercury resistant fecal bacteria was the mercury in people's mouths.
Sooner after, Summers teamed up with Lorscheider and Vimy at the University of Calgary to study the relationship among mercury amalgam, mercury resistance, and antibiotic resistance. Their groundbreaking 1993 study demonstrated that mercury released from amalgam fillings implanted in monkeys teeth caused a significant increase in resistance to mercury along with an alarming increase in antibiotic resistance in the oral and intestinal bacteria of primates.(154) The study also documents the results of Summers's earlier research on human fecal bacteria showing that those with a high prevalence of mercury resistant intestinal bacteria were significantly more likely to have a resistance to two or more antibiotics.
Scientists have known for some time that the genes that enable bacteria to resist the toxic effect of mercury are carried in the same DNA structures that carry the genes for antibiotic resistance. Summers and her colleagues have advanced scientific knowledge one step further. They have shown that once a bacterium is exposed to mercury and becomes mercury resistant, it is primed to become antibiotic resistant as well.(155) Yet another instance in which mercury amalgam fillings threaten our health and well being.