Updated: 8/22/05
Technical Health Report #120789
THE MERCURY REPORT:
Is there a hidden health hazard in your dental fillings? Don't let the growing controversy leave you confused. More than one hundred million Americans have "silver" amalgam fillings in their teeth. But few have been aware of the fact that amalgam fillings contain from 45 to 70 percent mercury, a highly toxic heavy metal (3 p 353).
Mercury toxicity can produce a devastating effect on one's physical, mental and emotional health and that can have a devastating effect on one's marriage, family, job and social life.
Mercury, also known as quicksilver, and its principal ore mineral, cinnabar, have been used by man for more than 2300 years (1). Mercury is commonly used in the chemical industry, electrical applications, in pharmacology, drugs and medicines, in the paint industry, in paper making, agriculture as well as in dentistry (1; 10 p 46; 11 p 318).
Mercury (Hg), a heavy metal, is unusual in that at normal temperatures it is a silvery liquid that has the ability to amalgamate with other metals to form a pliable alloy that hardens rapidly. It is this unique characteristic of mercury and its relative low cost that makes it so desirable as a dental material (3 p 353).
However, controversy and debate have raged for more than a century over the safety of using mercury in dental fillings. Can the mercury in amalgam fillings cause toxicity? Amalgam first began to be used for dental fillings in England, France and the U.S. more than 150 years ago (2, 4, 10 p 50). Gold had been used almost exclusively for about 2500 years before amalgam became available (10 p 174). Controversy in the U.S. over the safety of silver-mercury amalgam caused breakup of the National Association of Dental Surgeons about a century ago (4 p 12). The debate continues and heats up from time to time.
The FDA approved the use of mercury in fillings in a 1976 ruling that allowed continued use of certain substances already in wide use. The FDA has asked a government scientific advisory committee to evaluate recent studies on its safety (14,15). The New England Journal of Medicine notes, "many important medical questions concerning mercury toxicity remain to be answered." (15).
There is no question about the dangers of mercury toxicity. It has been known for centuries that mercury and compounds of mercury are potent poisons when swallowed, inhaled, or absorbed through the skin. The first recorded cases of mercury poisoning date back to ancient times (11 p 318).
Exposure to toxic levels of mercury is known to cause a variety of problems, including neurological and autoimmune disorders (14).
Reactions to mercury can be either toxic or allergic (10 p 116). Allergy to mercury is one of the most common causes of allergic dermatitis. Sensitization often occurs from non-dental exposures (p 125). Mercury allergy or sensitivity is most frequent after amalgams have been in the mouth more than five years (p 117).
Mercury causes suppression of the immune system, causing lymphocytes to revert back to immature forms (pp 117-118). The effects on the immune system can increase the risk of cancer, infection, allergies and autoimmune diseases (p 119).
All forms of mercury are poisonous if absorbed (7). Organic forms, such as Methyl mercury (commonly used as a fungicide), are the most toxic, being 100 to 1000 times as toxic as mercury vapor, readily affecting the central nervous system. The metallic form is the least toxic, but it gives off toxic vapors and is easily changed to organic forms by bacteria (10, pp 44-46,110). Both methyl mercury and mercury vapor can cross the blood brain barrier and the placenta (p 113). Mercury is the most toxic of a group of toxic heavy metals that include lead and cadmium (p 113).
Mercury's highly toxic effects are related to its strong chemical attraction to sulfur and other elements which are components of amino acids, antibodies, enzymes, hormones and proteins - molecules vital to the functions of all the cells and tissues of the body (10 p 24). Mercury inhibits enzyme functions, collagen synthesis, interferes with membrane permeability and nutrient uptake, blocks metabolism of neurones, nerve conduction and causes death of nerve cells (p 114). As little as 0.5 gram of mercury bichloride can cause death (7). Autopsies of those who died soon after exposure revealed degenerative lesions of the liver, heart muscle fibers and kidneys (5).
Chronic poisoning can also occur from absorption of very small amounts of mercury over a long period of time because mercury is a cumulative poison affecting all tissues. Only small numbers of mercuric ions are necessary to cause cellular damage. Symptoms become progressively worse eventually ending in death or increased susceptibility to other diseases. Mercury vapor levels as low as 10 micrograms (a microgram is one 10 millionth of a gram) per cubic meter of air caused poisoning in researchers (10 pp 113-114). Mercury is eliminated slowly from the body. About one half of a single dose (half-life) of mercury is eliminated in about 65 days from the body of a normal individual, but the half-life from the brain is about 18 to 22 years (pp 123, 143). Damage to the liver kidneys and lungs impairs the bodies ability to eliminate mercury and other toxic substances thereby increasing toxicity and time for elimination.
Chronic poisoning from very low levels of exposure may be so gradual and symptoms so vague that one may not realize he is being poisoned and it may be difficult to identify the cause. As mercury accumulates liver, kidneys, brain, immune system and other tissues are damaged. Health gradually deteriorates reducing the ability to adapt to other stresses in the environment (10 pp 18). A National Institute of Health (NIH) report describes symptoms of chronic low dose exposure to mercury as follows:
"First degree micromercurialism results in lowered working capacity, increased fatigue, light nervous excitability... in the second degree there is swelling of the nasal membranes, progressive weakening of memory, feelings of fear and loss of self-confidence, irritability, headaches. Simultaneously there may be catarrhal symptoms and upper respiratory discomfort, changes in the mucous membranes of the mouth, bleeding gums. Sometimes there are feelings of coronary insufficiency, shivering, quickening pulse, and a tendency towards diarrhea. The third degree micromercurialism is characterized by symptoms approaching those of regular mercurialism... headaches, general weakness, sleeplessness, decline in intellectual capacity, depression. Among other signs are tears, diarrhea, frequent urination, a feeling of pressure in the cardiac region and shivering." (10, p 22)
Chronic Neurological symptoms include depression, irritability exaggerated response to stimuli, excessive shyness, insomnia, anxiety, emotional instability, forgetfulness and confusion. Other neurological signs include spasms of the arms, legs or facial muscles (chorea), body tremors and fine trembling of fingers, eyelids, lips, and tongue, lack of muscle coordination, mental retardation, excessive perspiration, and uncontrollable blushing (10, p 21). Additional symptoms include weakness, fatigue, inflammation of the mouth, metallic taste, loosening of teeth, excessive salivation, formation of a blue line on the gums, pain, numbness, staggering gate, tunnel vision, garbled speech, impaired chewing or swallowing, loss of weight and appetite, mental and personality changes marked by depression and a tendency to withdraw (1;2;5;6).
Methyl mercury can cause chromosome damage and produce birth and genetic defects (11 p 320). Toxicity from other chemicals can also cause or add to these symptoms.
Everyone is exposed to mercury to some degree. Mercury is used widely in industry, in products used in the home, on the job, on the farm, in medicine and in dentistry and has polluted the environment and foods. The New England Journal of Medicine cites the mercury in fillings as "possibly the chief source of exposure of a large segment of the U.S. population." (15). The amount of exposure from any one source is generally not sufficient to cause symptoms. However, because of the cumulative nature of mercury the combined exposure from several sources greatly increases the hazard of toxicity.
Back to our original question, "Does the mercury in 'silver' amalgam dental fillings pose a potential health hazard"?
The American Dental Association (ADA), insists that amalgam fillings are safe. Only people allergic to mercury [experts estimate 1 to 2 percent of the population is allergic to mercury amalgam fillings (14)] need to avoid them, the ADA says (2). An ADA president Dr. R. M. Overbey said, "No epidemiological studies have shown adverse effects with any demonstrated correlation to amalgam" (15). Robert Sheridan, a director of the FDA's office of device evaluation, stated, "We believe that the data to date are not sufficient to demonstrate clinical harm to patients." Animal studies that show significant mercury absorption from dental filling, and some anecdotal accounts of harmful effects in humans, are compelling and raise important questions, he said, but no studies have been done in humans and there is no evidence that mercury amalgam fillings cause disease (14).
On the other hand, some researchers believe that mercury vapors are released and absorbed from fillings and may affect the brain, kidneys, immune system and other tissues (14). These scientists say that mercury toxicity from fillings may be causing a wide range of problems affecting the health of possibly more than 20% of the population (4 p 8). According to them, conditions potentially caused by mercury toxicity include irritability, insomnia, depression, forgetfulness, severe mood changes, suicidal tendencies, headaches, backaches, chronic fatigue, tachycardia, allergies, immune deficiencies, birth defects, multiple sclerosis, Hodgkin's disease, leukemia and a host of other symptoms and often undiagnosed diseases (4 pp 35-46; 2).
In recent years, the Swedish Government Health Board reevaluated the toxic potential of mercury as unsuitable as a dental material, reversing their earlier stand (8). "We now realize that we have made a mistake", acknowledged Viking Falk, division chief at the Socialstyrelsen, "this has caused people to suffer unnecessarily". (9)
The greatest danger is considered to be to the unborn fetus in pregnant women. Pregnant women exposed to mercury without symptoms have given birth to children who later developed cerebral palsy (10 pp 21-22). Research by Sweden's prestigious Karolinska Institute reveals evidence from infant cadavers that mercury passes through the placentas of mothers with amalgam fillings and accumulates in infant brain tissue (15). The Swedish government strongly recommends against using amalgam in the mouths of pregnant women. A ban is being considered on the substance altogether (15). Though the board considers mercury exposure from amalgam to be very low and that the number of patients with problems caused by mercury ought to be very small. (8)
The toxic effects of mercury and many other chemicals have been well established. It is already an accepted fact that some, perhaps 1 to 2 percent of the population will react allergically to mercury (altering immune functions and possibly causing autoimmune diseases) and that corrosion products of dental amalgam may retard healing of gingival tissues (gums) and periodontal disease (10, p 118; 17, p 32-33, 465-67).
The major controversy in dentistry is centered on the issue of whether or not the amount of mercury released from the amalgam fillings and adsorbed into the body is enough to cause toxicity. The safety or toxic potential of amalgam fillings is largely a question of how stable or how susceptible amalgam fillings are to corrosion in the mouth.
According to a dentistry book "Science of Dental Materials" the oral environment is very conducive to corrosion (3, p 287). Corrosion of amalgam fillings is a well recognized problem in dentistry (3, pp 344-345). Corrosion is caused by physical (chewing), chemical (acids), and electrolytic forces and has been proven to release significant amounts of mercury (3 chapters 19,22; 10, pp 107-110).
Studies show chewing increases mercury release an average of 15.6 times (10, pp 108-109). Acids and sulfides from various foods also increase corrosion (3, pp 287,288). However, electrolytic corrosion, usually associated with chemical corrosion is of greater significance (p 290). Amalgam fillings with saliva generate an electric current of up to 500 millivolts and commonly cause a "galvanic shock" with involuntary bitting of the tongue and cheeks as well as corrosion (3, pp 291-297). Higher levels of copper added to amalgam fillings in the 70's when silver prices peaked resulted in higher levels of electrolytic corrosion and leaching of mercury.
Scientists have estimated that as much as 25 to 45 micrograms of mercury per day could be released from amalgam fillings (10, p 140). Analysis of 5 to 20 year old fillings showed loss of 10 to 45% of the mercury due to corrosion (p 108). The amount of mercury liberated over a period of time could be as much as 30 to 560 milligrams (a milligram is 1/1000 of a gram), depending on the size and number of fillings (p 110).
A Canadian research team, headed by University of Calgary dentist Murray Vimy, reported that mercury from amalgam causes kidney malfunction in test animals. The researchers put silver amalgam fillings in the mouths of six sheep. All animals showed some kidney dysfunction after 30 days. The average loss of kidney function was 50%. Two control animals getting fillings of an inert substance showed no change in function. New primate studies done by this group show concentrations of mercury in kidney's, livers and gastrointestinal tracts as a result of amalgam fillings (15).
Medical specialists dealing with environmental diseases indicate that mercury is one of many factors causing environmental illnesses (pp 154-156). The potential toxic effects of mercury from dental fillings to an individual will be determined by a number of factors including; how much mercury one is getting from all sources including dental fillings, occupational exposure, foods, industrial products, wastes and environmental sources; the additive effects of other toxic substances such as lead, pesticides and other pollutants to one's health; and one's natural resistance or tolerance level.
The dental dilemma goes much deeper than simply a controversy over the safety of amalgam fillings. Dentists are doing the best they know how to repair peoples dental problems. But humans have often been unable or unwilling to come to total agreement on what are the right or best ways. The solution will require a greater degree of mutual cooperation by everyone.
In the meantime, if you have health problems related to mercury toxicity or other toxic substances, what should you do? Regaining health or maintaining health takes motivation, study and hard work. It doesn't just happen (pp 167-168). Learning to avoid exposure to substances containing toxic materials, and maintaining a healthy lifestyle with good diet, exercise, and a right mental attitude are important. Should you run down and have all your amalgam fillings removed. Seek good consultation and medical advise.
Many have had a positive health response to having amalgam fillings removed. Dr. Michael Pawk, a Pennsylvania dentist told the FDA panel on dental products that he stopped using mercury amalgams after evaluating the scientific literature. He said that after he stopped, he was even more convinced because he has seen too many people respond and too many health conditions disappear (14).
From one who has suffered the effects of both acute mercury poisoning from a mercury fungicide used on grain and later chronic mercury poisoning resulting from slow accumulation of mercury from corroding amalgam fillings put in during the 70's, it is hard to understand why there should be any controversy. Wouldn't it be much better to error on the side of safety than to play Russian roulette with mercury fillings. The toxic effects of mercury are very real both personally and on family and loved ones. The difficulty in coping with stresses and minor irritations, increased sickness, chemical allergies, chronic fatigue, fibromyalgia, forgetfulness and other mental difficulties and just trying to make a living, become major problems. Removal of the mercury fillings has reversed the problem of mental deterioration, but the fight back is difficult and slow. One might wonder how many people with undiagnosed (idiopathic) sicknesses, mental conditions and dropouts from society and how much crime could be the result of various chemical toxicities including mercury.
Results from removing amalgam fillings may vary from positive to negative. Some have seen dramatic improvement in conditions such as apparent multiple sclerosis, angina, and various immune disorders, allergies, leukemia, Hodgkin's disease and cancer (4 pp 32-46; 10 p 149). Other improvements noted were increased energy level, increased appetite, better food and chemical tolerances and a decrease in headaches (pp 156-160).
Negative effects from removing mercury fillings can result from increased exposure during the removal process combined with previous toxic damage. Dr. David Eggleston, dental researcher with the USC School of Dentistry, says that, "Sometimes when fillings are removed patients are exposed to more mercury than if the fillings are left alone." and, "there is a temporary elevation of mercury in the blood." He suggests that worried patients discuss alternative materials when a new cavity is found or a silver (mercury) filling has to be replaced. But patients, including pregnant women, should not request wholesale removal of silver fillings (15).
* Porcelain resin composites - These work well for small fillings, but are less durable in larger restorations. They are available in color or natural tooth. Costs are about the same as amalgam, but may not last as long.
* Porcelain inlays or crowns - Last 20-30 years, are natural color of tooth.
* Gold inlays or crowns - Last 25-30 years, are yellow gold color.
Almost everyone is exposed to mercury, a highly toxic, liquid, silvery metal found in many thermometers. Because of its widespread use, traces and sometimes toxic levels of the heavy metal or compounds of it are found in the air we breath, the water we drink, the food we eat, and in many other common sources in the home, on the farm, on the job, and in the environment.
Acute or chronic cumulative mercury intoxication causes a complex of difficult to diagnose and treat disease conditions. Mercurial compounds have in the past been commonly used in clinical medicines as antiseptics, antisyphilitics, cathartics, and diuretics (7). Mercurial diuretics have caused asthma, hives and other skin lesions, kidney and liver damage and sudden death. Ointments containing mercury, and calomel, a mercurous chloride cathartic (strong laxative), have caused fever, rash, and enlargement of the spleen and lymph nodes (5).
The "mad hatter" syndrome, immortalized in "Alice in Wonderland", is a classic example of occupational mercury poisoning. Hat makers in the 19th century dipped felt into a solution of mercuric-nitrate to make it easier to shape. Absorption of the mercury resulted in chronic nervous disorders and madness (2).
Mercury is used on a substantial scale in numerous industries, such as for refining of gold, manufacture of chemicals, paints, thermometers, batteries, medicines, fluorescent and mercury vapor lights and sun lamps, paper, inks, cosmetics, disinfectants, insecticides, fungicides, embalming fluids, explosive devises, electrical switches, dental fillings and other products. Organic mercurial compounds such as methyl mercury are used widely in agriculture as insecticides and as fungicides to treat seed grains to prevent mildew. Mercury compounds are also used on lumber to prevent decay and discoloration, and in laundries to prevent garment mildew (4 pp 100-102; 5; 6; 10 p 47). Every known mercury compound is potentially hazardous (7).
Dentists and dental personnel are in a high risk category from handling mercury for amalgam fillings. They show average mercury levels 4 to 5 times higher than the average (2; 10 pp 68-69). Mortality studies of dentists show a significantly higher incidence of brain cancer, cardiovascular, renal and respiratory disease, suicide, and ill-defined causes of death compared to the general population (10 p 72).
OSHA (the Occupational Safety and Hazard Agency of the U.S. Public Health Service) has set limits for mercury exposure allowable in the work place. U.S. safety limits have been set at 50 micrograms per cubic meter of air, 5 times higher than the allowable levels for Switzerland, Russia and Germany (4 p 47; 10 pp 74, 105-106).
Scientists estimate the average intake of mercury from the air is nearly 0.6 micrograms (a microgram is millionth of a gram). The mercury concentration in the air ranges from 1 nanogram (a billionth of a gram) per cubic meter over oceans to over 10,000 nanograms near mercury deposits and areas of volcanic activity (10 p 44).
Environmental pollution is said to be increasing at a rapid rate. Burning of coal and oil is releasing significant amounts of mercury (more than 3000 metric tons per year) into the atmosphere (11 p 319). Industrial and biological processes concentrate mercury compounds to dangerous levels and contaminate air, water, soils and foods (5).
Not only is mercury increasing in the environment, but evidence suggests that more of it is in the organic form that is most toxic to humans (6). Bacteria can convert the inorganic mercury into the much more toxic organic forms such as methyl mercury. Algae concentrate the methyl mercury and is then eaten by fish. At each step up the food chain, the concentration of mercury increases. The larger and older the fish, the higher the concentration of mercury (11 p 318). Scientists estimate the average intake of mercury from food to be from 5 to about 25 micrograms per day (10 pp 43,110). People eating fish daily had mercury levels over 8 times higher than those eating fish only once per month (p 112).
Neurological Poisoning with organic mercurial compounds became known as Minamata disease in Japan because of a tragic outbreak of mercury poisoning that occurred in Minamata, Japan in the early 1950's. Fish and shellfish became contaminated with mercury from industrial effluent dumped into the bay. People eating the fish and shellfish developed progressive weakening of the muscles, loss of vision, impairment of the cerebral functions, eventual paralysis, and in many cases, coma and death. Fish were dying and seabirds and cats subsisting on fish also showed signs and were dying of the same disease (5). Dumping of mercury in Minamata Bay by a local plastics factory began in 1932. By the 50's, mercury concentrations in the water increased 15 to 36 times above the normal 0.1 part per billion (ppb). The levels in the liver, kidneys and brains of victims reached up to 200 times the normal levels (13 p 607). Pollution wasn't stopped until 1968 and it was 1973 before cleanup began. In the meantime, the death count climbed to 871 and thousands have been left painfully crippled. Another effect has been a deep social rift created between families of victims and non-victims. Many of the non-victims were employees who feared for their jobs if they protested the mercury dumping. Victims were made fun of and told to "get out." Some received hate mail, were called names and told they should "just die" (12).
Mercury pollution of some of the great lakes and Oswege and Niagara Rivers in the 1970's by chemical and paper pulp companies caused the U.S. government to issue warnings to fishermen not to eat or sell fish caught in those waters (11 p 318).
Mercury treated grain has also caused outbreaks of the disease involving large numbers of persons. In 1972, several thousand people in Iraq suffered neurological damage and several hundred died from eating treated wheat and barley seeds. Farmers who received grain seeds treated with an organic mercury fungicide ate the seeds instead of planting them (5). Another striking case occurred in New Mexico when a worker fed seed grain sweepings to his hogs. Within two weeks of eating the poisoned pork, three out of the family of ten were stricken with brain and spinal cord damage. One girl lay unconscious for eight months in the hospital before waking totally blind and unable to speak (11 p 319).
In 1996 a scientist, Dr. Karen Wetterhahn, a chemistry professor at Dartmouth working under a $7 million federal grant to study toxic metals, suffered a horrible death after just one drop of an experimental mercury compound - dimethyl mercury - spilled on her protective glove and seeped through to her skin. Symptoms began gradually like a stomach flue, but then she began bumping into doors and suddenly falling down as if drunk. Words became difficult, her hands tingled and five months after the spill she was taken to the emergency room. Symptoms then progressed rapidly, by the weekend she couldn't walk, her speech was slurred and her hands trembled. Diagnosed as mercury poisoning, treatment was started immediately, but little was known about the rare man-made chemical dimethyl mercury, a colorless liquid that looks like water but is three time heavier and far more toxic than other forms of mercury. Scientists didn't know it could seep through a latex glove like water through a Kleenex. Now, six months later Karen's body was riddled with it. Doctors didn't know it could break down the body over the course of a few months, slowly, insidiously, irreversibly and no one knew how to stop its deadly progress, as it cut off her hearing, her speech, her vision reducing her body to a withered shell. Ten days after the diagnosis she fell into a coma and four months later she died. There was only one other documented case of dimethyl mercury poisoning, a Czech chemist in 1972 who had suffered the same symptoms as Karen and died. (The Columbian, Sept 22, 1997, Associated Press).
The true extent of mercury poisoning is unknown. Diseases caused by mercury are difficult to diagnose. It has not been generally recognized as a major problem, but then except for the more dramatic outbreaks, it has not been extensively studied.
Mercury is one of hundreds of toxic substances we are being exposed to at ever increasing rates. Outbreaks such as the incidences in Minamata Japan, Iraq, New Mexico, and the Great Lakes should serve as a strong warning to what unchecked industrial pollution and careless handling of toxic substances can do to humans, wildlife and their surroundings (12). Strong regulations, education and enforcement are needed to prevent the suffering and tragedies that are commonplace today.
© Copyright 1989 - Allen L. Stout, 2003 Serf Publishing, Inc.
Last Update: 11-5-02