Mercury Exposure Levels from Amalgam Dental Fillings; Documentation of Mechanisms by Which Mercury Causes over 30 Chronic Hea

Mercury Exposure Levels from Amalgam Dental Fillings; Documentation of Mechanisms by Which Mercury Causes over 30 Chronic Health Conditions; Results of Replacement of Amalgam Fillings; and Occupational Effects on Dental Staff

Bernard Windham, Editor- Chemical Engineer 12164 Whitehouse Road

Tallahassee, FL,32311 850-878-9024

I. Introduction

II. Toxicity and Health Effects of Mercury

III. Systemic Mercury Intake Levels from Amalgam Filling Exposure

IV. Immune System Effects and Autoimmune Disease

V. Medical Studies Finding Health Problems Related to Amalgam Fillings

VI. Documented Results of Removal of Amalgam Fillings

VII. Tests for Mercury Level and Toxicity and Treatments

VIII. Health Effects from Dental Staff Exposure to Mercury IX. Scientific Panel and Government Bodies That Have Found Amalgam Fillings Unsafe

I. Toxic metals such as mercury, lead, cadmium, etc. have been documented to be neurotoxic, immunotoxic, reproductive/developmental toxins that according to U.S. Government agencies cause adverse health effects and learning disabilities to millions in the U.S. each year, especially children and the elderly(160,105,27d). Exposure of humans and animals to toxic metals such as mercury, cadmium, lead, copper, aluminum, arsenic, chromium, manganese, etc. is widespread and in many areas increasing. . The U.S. Center for Disease Control(276) ranks toxic metals as the number one environmental health threat to children. According to an EPA/ATSDR assessment, the toxic metals mercury, lead, arsenic, and cadmium are all ranked in the top 7 toxics having the most adverse health effects on the public based on toxicity and current exposure levels in the U.S., with nickel and chromium also highly listed. The U.S. EPA indicates that approximately 25% of U.S. infants are exposed to dangerous levels of mercury(276). A National Academy of Sciences report of July 2000 and other studies(39,125,308,540) found that even small levels of mercury in fish or levels of mercury in the blood of women below 10 micrograms per liter(ug/l) appear to result in developmental effects, and represent unacceptable risks of birth defects and developmental effects in infants. A California clinical study found adverse effects at exposures below 10 ug/l(540). 1 ug/l is the upper level of mercury exposure recommended by the German Commission on Human Biomonitoring in the blood(39). The National Academy of Sciences safety limit is 5 micrograms per liter. But blood level is also documented to not be a reliable indicator of mercury toxicity since mercury vapor passes out of the blood in a very short time. And mercury amalgam dental fillings have been found to be the largest source of both inorganic and methyl mercury in most who have several amalgam fillings.

The main factors determining whether chronic conditions are induced by metals appear to be exposure and genetic susceptibility, which determines individuals immune sensitivity and ability to detoxify metals(405,342). Very low levels of exposure have been found to seriously affect relatively large groups of individuals who are immune sensitive to toxic metals, or have an inability to detoxify metals due to such as deficient sulfoxidation or metallothionein function or other inhibited enzymatic processes related to detoxification or excretion of metals. For those with chronic conditions, fatigue regardless of the underlying disease is primarily associated with hypersensitivity to inorganic and organic mercury, nickel, and gold(342,369,375,382).

While there have been large increases of most neurological and immune conditions among adults over the last 2 decades(574), the incidence of neurotoxic or immune reactive conditions in infants such as autism, schizophrenia, ADD, dyslexia, learning disabilities, etc. have been increasing especially rapidly in recent years (2,409,441,476). A recent report by the National Research Council found that 50% of all pregnancies in the U.S. are now resulting in prenatal or postnatal mortality, significant birth defects, developmental neurological or immune conditions, or otherwise chronically unhealthy babies(441). Exposure to toxic chemicals or environmental factors appear to be a factor in as much as 28 percent of the 4 million children born each year(441,160), with 1 in 6 having one of the neurological conditions previously listed. EPA estimates that over 3 million of these are related to lead or mercury toxicity (2,125,276,409), with approximately 25% of U.S. infants receiving dangerous levels of mercury exposure(276). A recent study found that prenatal Hg exposure is correlated with lower scores in neurodevelopmental screening, but more so in the linguistic pathway(32c). A study at the U.S. CDC found "statistically significant associations" between certain neurologic developmental disorders such as attention deficit disorder(ADD) and autism with exposure to mercury from thimerosal‑containing vaccines before the age of 6 months(476), and a followon study using federal vaccine data bases confirmed that autism, speaking disorders, and heart arrest have increased exponentially with increasing exposures to mercury thimerosal-containing vaccines(476b). Thimerosal has also been found to cause hormonal effects(555,413). Prenatal exposure to mercury has also been found to predispose animals and infants to seizures and epilepsy(5,52).

The health effects of toxic metals are synergistic with other toxic exposures such as pesticides, endocrine disrupting substances like organochlorine compounds and PCBs, etc. There are also synergistic effects with the various types of parasites, bacteria, viruses to which people have common exposures and commonly become infected when the immune system is weakened by toxic exposures(485,469b,470) While there is considerable commonality to the health effects commonly caused by these toxic metals, and effects are cumulative and synergistic in many cases, this paper will concentrate on the health effects of elemental mercury from amalgam fillings. Studies have found considerable genetic variability in susceptibility to toxic metals as well. The public appears to be generally unaware that considerable scientific evidence supports that mercury is the metal causing the most widespread adverse health effects to the public, and amalgam fillings have been well documented to be the number one source of exposure of mercury to most people, with exposure levels often exceeding Government health guidelines and levels documented to cause adverse health effects.

II. Toxicity and Health Effects of Mercury

1. Dental amalgam contains about 50 % mercury, as well as other toxic metals such as tin,copper,nickel, palladium, etc. The average filling has 1 gram of mercury and leaks mercury vapor continuously due to mercury’s high volatility along with loss due to galvanic action of mercury with dissimilar metals in the mouth (182,192,276b,292,348,349,525), resulting in significant exposure for most with amalgam fillings(see Section III). Mercury vapor is transmitted rapidly throughout the body, easily crosses cell membranes, and like organic methyl mercury has significant toxic effects at much lower levels of exposure than other inorganic mercury forms (38,281,287,304,329). The OSHA level for mercury vapor in air is 50% lower than for organic mercury in air. According to the U.S. EPA & ATSDR, mercury is among the top 3 toxic substances adversely affecting large numbers of people(217), and amalgam is the number one source of exposure for most people(see III).

A large U.S. Centers for Disease Control epidemiological study, NHANES III, found that those with more amalgam fillings(more mercury exposure) have significantly higher levels of chronic health conditions(543). The conditions in which the number of dental amalgam surfaces were most highly correlated with disease incidence were MS, epilepsy, migraines, mental disorders, diseases of the nervous system, disorders of the thyroid gland, cancer, and infectious diseases (543). Other conditions where incidence was significantly correlated with having more than the average number of amalgam surfaces are: diseases of the male and female genital tracts, Disorders of the peripheral nervous system, Diseases of the respiratory system, and Diseases of the genitourinary system (543). MS clusters in areas with high metals emissions from facilities such as metal smelters have been documented(184).

As far back as 1996 it was shown that the lesions produced in the myelin sheath of axons in cases of multiple sclerosis were related to excitatory receptors on the primary cells involved called oligodendroglia. The loss of myelin sheath on the nerve fibers characteristic of the disease are due to the death of these oligodendroglial cells at the site of the lesions (called plaques). Further, these studies have shown that the death of these important cells is as a result of excessive exposure to excitotoxins at the site of the lesions(576,585). Most of these excitotoxins are secreted from microglial immune cells in the central nervous system. This not only destroys these myelin-producing cells it also breaks down the blood-brain barrier (BBB), allowing excitotoxins in the blood stream to enter the site of damage. Some common exposures that cause such proliferation of such excitotoxins resulting in MS are mercury and aspartame, with additional effects from MSG and methanol. Mercury and other toxic metals inhibit astrocyte function in the brain and CNS(119), causing increased glutamate and calcium related neurotoxicity (119,333,416,496) which are factors in neural degeneration in MS and ALS. There is evidence that astrocyte damage/malfunction is a major factor in MS(544). Mercury and increased glutamate activate free radical forming processes like xanthine oxidase which produce oxygen radicals and oxidative neurological damage(142,13). Nitric oxide related toxicty caused by peroxynitrite formed by the reaction of NO with superoxide anions, which results in nitration of tyrosine residues in neurofilaments and manganese Superoxide Dimustase(SOD) has been found to cause inhibition of the mitochondrial respiratory chain, inhibition of the glutamate transporter, and glutamate-induced neurotoxicity involved in ALS(524,521).

It is now known the cause for the destruction of the myelin in the lesions is overactivation of the microglia in the region of the myelin(585). An enzyme that converts glutamine to glutamate called glutaminase increases tremendously, thereby greatly increasing excitotoxicity. Any dietary excitotoxin can activate the microglia, thereby greatly aggravating the injury. This includes the aspartate in aspartame and MSG which is in many processed foods. The methanol in diet drinks adds to this toxicity as well. Now, the secret to treatment appears to be calming down inflammation of the microglia.

Mercury and cadmium inhibiting magnesium and zinc levels as well as inhibiting glucose transfer are other mechanisms by which mercury and toxic metals are factors in metabolic syndrome and insulin resistance/diabetes (43,198,338,589). Reduced levels of magnesium and zinc are related to metabolic syndrome, insulin resistance, and brain inflammation and are protective against these conditions(587,43).

According to neurologist Dr. RL Blaylock(585), the good news is that there are supplements and nutrients that calm the microglia-the most potent are: silymarin, curcumin and ibuprophen. Phosphatidylcholine helps re-myelinate the nerve sheaths that are damaged, as does B12, B6, B1, vitamin D, folate, vitamin C, natural vitamin E (mixed tocopherols) and L-carnitine (576) . DHA plays a major role in repairing the myelin sheath. Vitamin D may even prevent MS, but it acts as an immune modulator, preventing further damage - the dose is 2000 IU a day. Magnesium, as magnesium malate, is needed in a dose of 500 mg 2X a day. They must avoid all excitotoxins, even natural ones in foods-such as soy, red meats, nuts, mushrooms and tomatoes. Avoid all fluoride and especially all vaccinations since these either inhibit antioxidant enzymes or triggers harmful immune reactions.

2. Mercury is the most toxic of the toxic metals. Mercury (vapor) is carried by the blood to cells in all organs of the body where it:

(a) is cytotoxic(kills cells) (2,21,27,36,56,147,148,150,160,210,259,295,333/333)

(b) penetrates and damages the blood brain barrier(311), resulting in accumulation of mercury and other toxic substances in the brain(14,20,21b,25,85,99,175,273,301,305,/149,262,274); also accumulates in the motor function areas of the brain and CNS(48,119,175,291,327,329).

© is neurotoxic(kills brain and nerve cells): damages brain cells and nerve cells (19,27,34,36, 43, 69,70, 147,148,175,207,211,258,273,291,295,327,329,301,303,305,395/39,262,274,303); generates high levels of reactive oxygen species(ROS) and oxidative stress, depletes glutathione and thiols causing increased neurotoxicity from interactions of ROS, glutamate, and dopamine (13,56,98,102, 145,169,170, 184,213,219,250,257,259,286,288,290,291,302,324,326,329,416,424, 442, 496,564,565); kills or inhibits production of brain tubulin cells (66,67,161,166, 207,258,300); inhibits production of neurotransmitters by inhibiting: calcium-dependent neurotransmitter release(372,432), dihydroteridine reductase (27,122,257,333), nitric oxide synthase(259), blocking neurotransmitter amino acids (412), and effecting phenylalanine, serotonin, tyrosine and tryptophan transport to neurons (34,122,126,257,285,288,333,372,374,412/333)

(d) is immunotoxic(damages and inhibits immune T-cells, B-cells, neutrophil function, etc.) (17,27,31,38,44,45,46,60,127,128,129,130,152,155,165,181,226,252,270,285,316,343,355,425,467/272) and induces ANA antibodies and autoimmune disease (38,43,45,59,60,118,181, 234,269,270,313,314,334, 342,343,425, 405)

(e) is nepthrotoxic(toxic to kidneys) (14,20,203,209c,223,254,260,268,334,438)

(f) is endocrine system-disrupting chemical(accumulates in pituitary gland and damages or inhibits pituitary glands hormonal functions at very low levels (9,19,20,25,85,99,105,273,312,327, 348,369/274), adrenal gland function(84,369,381), thyroid gland function (50,212,369,382,459,508-511,35), thymus gland function(513a), and disrupts enzyme production processes at very low levels of exposure (9,13,33,35,56,111,194,258,348,355,410-412)

(g) exposure to mercury vapor (or methyl mercury) causes rapid transmittal through the placenta to the fetus (20,22-24,27,38,39,61,112,186,281,287,304,311,338,339,348,361,366,20/ 4,22,37,39, 41,42) and significant developmental effects-much more damage to the fetus than for maternal exposure to inorganic mercury and at lower exposure levels than for organic mercury(287,304,276e,etc.).

(h) reproductive and developmental toxin (2,4,9,10,22,23,24,31,37,38,41,61,105,125, 160,175,275, 281,305, 338,361,367,381,20/4,39,55,149,162,255,308,339,357,540); damages DNA (296,327,272,392,142,38,41,42,35) and inhibits DNA & RNA synthesis (114,175,35/149); damages sperm, lowers sperm counts and reduces motility. (4,37,104.105,159,160,433,35/4,55,162); causes menstrual disturbances (9,27,146); reduces bloods ability to transport oxygen to fetus and transport of essential nutrients including amino acids, glucose, magnesium, zinc and Vit B12 (43,96,198,260d,264,338,339,347,427); depresses enzyme isocitric dehydrogenase (ICD) in fetus, causes reduced iodine uptake & hypothyroidism (50,91,212,222,369,382,390,459,35ab) ; causes learning disabilities and impairment, and reduction in IQ (1,3,38,110,160,285c,264,338,509/39), causes infertility (4,9,10,24,38,121,146,357, 365, 367,511 /4,10,55, 162), causes birth defects (23,35ab,37,38,50,110,142,241,338c,509,511/241).

(i) prenatal/early postnatal exposure affects level of nerve growth factor in the brain, impairs astrocyte function, and causes imbalances in development of brain (38,119,131,161,175,194,305,458/149,255,39)

(j) causes cardiovascular damage and disease: including damage to vascular endothelial cells, damage to sarcoplasmic reticula, sarcolemma, and contractile proteins, increased white cell count, decreased oxyhemoglobin level, high blood pressure, tachycardia, inhibits cytochrome P450/heme synthesis(84,35,201,539), and increased risk of acute myocardial infarction (35,59,201,202,205,212,232,306,310,351,510,50/201,308).

(k) causes immune system damage resulting in allergies, asthma, lupus(234,260e),schleraderma(468),chronic fatigue syndrome(CFS),and multiple sensitivities(MCS) (8,17,26,35,45,46,60,75,86,87,90,95,97, 101,128,129,131,132,154,156,168,181,212, 226,228,230,234,265,267,296,313,342,388,445, 446/272) and neutrophil functional impairment (285,404,467/59,etc.).

(l) causes interruption of the cytochromeC oxidase system/ATP energy function (43,84,232,338c,35) and blocks enzymes needed to convert porphyrins to adenosine tri phosphate(ATP) causing progressive porphyrinuria, resulting in low energy, digestive problems, and porphyrins in urine (34,35,69,70,73,210,212,226,232,258,260)

(m) inhibition of immune system facilitates increased damage by bacterial, viral, and fungal infections (17,45,59,129,131,251,296,350,40),and increased antibiotic resistance (116,117,161,389,53,79).

(n) mercury causes significant destruction of stomach and intestine epithelial cells, resulting in damage to stomach lining which along with mercury’s ability to bind to SH hydroxyl radical in cell membranes alters permeability(338,405,35,21c) and adversely alters bacterial populations in the intestines causing leaky gut syndrome with toxic, incompletely digested complexes in the blood(222,228b,35) and accumulation of heliobacter pylori, a suspected major factor in stomach ulcers and stomach cancer(256) and candida albicans, as well as poor nutrient absorption.

(o) forming strong bonds with and modification of the-SH groups of proteins causes mitochondrial release of calcium (1,21,35,38,43,329,333,432),as well as altering molecular function of amino acids and damaging enzymatic process(33,96,111,194,252,338,405,410-412) resulting in improper cysteine regulation(194), inhibited glucose transfer and uptake(338,254), damaged sulfur oxidation processes(33,194,338), and reduced glutathione availability (necessary for detoxification)(13,126,54).

(p) HgCl2 inhibits aquaporin‑mediated water transport in red blood cells(479).

3. Mercury has been well documented to be an endocrine system disrupting chemical in animals and people, disrupting function of the pituitary gland, thyroid gland, reproduction processes, and many hormonal functions at very low levels of exposure . Mercury (especially mercury vapor) rapidly crosses the blood brain barrier and is stored preferentially in the pituitary gland, thyroid gland, hypothalamus, and occipital cortex in direct proportion to the number and extent of dental amalgam surfaces (1,14,16,19,20,25,34,38,50,61,85,99,162,211,273,274,287, 327,348,360,366, 369) Thus mercury has a greater effect on the functions of these areas. Studies have documented that mercury causes hypothyroidism(50,390,35), damage of thyroid RNA(458), autoimmune thyroiditis (369,382,91) and impairment of conversion of thyroid T4 hormone to the active T3 form(369,382,459,35,50d,91). An overactive thyroid gland, or hyperthyroidism, can trigger restlessness, hyperactivity, insomnia and irritability - symptoms that could be mistaken for mania(560). On the other hand, a thyroid gland that responds sluggishly in a hypothyroid state may result in feelings of coldness, depression, pain, and low energy. Overt autoimmune thyroiditis is preceded by a rise in levels of thyroid peroxidase antibodies. "Collectively, reports show that 30-60% of women positive for TPO antibodies in pregnancy develop postpartum thyroiditis," the researchers point out(561), calling it "a strong association." Without treatment, many of the women with thyroiditis go on to develop overt clinical hypothyroidism as they age and, eventually, associated complications such as cardiovascular disease. About 5% of pregnant women develop thyroiditis after birth.

According to survey tests, 8 to 10 % of untreated women were found to have thyroid imbalances so the actual level of hypothyroidism is higher commonly recognized(508). Even larger percentages of women had elevated levels of antithyroglobulin(anti-TG) or antithyroid peroxidase antibody(anti-TP). Studies indicate that slight imbalances of thyroid hormones in expectant mothers can cause permanent neuropsychiatric damage in the developing fetus(509). Low first trimester levels of free T4 and positive levels of anti-TP antibodies in the mother during pregnancy have been found to result significantly reduces IQs(509). Hypothyroidism is a well documented cause of mental retardation(509). Women with the highest levels of thyroid-stimulating-hormone(TSH) and lowest free levels of thyroxine 17 weeks into their pregnancies were significantly more likely to have children who tested at least one standard deviation below normal on an IQ test taken at age 8. Based on study findings, maternal hypothyroidism appears to play a role in at least 15% of children whose IQs are more than 1 standard deviation below the mean, millions of children. Studies have also established a “clear association” between the presence of thyroid antibodies and spontaneous abortions(511), as well as a connection between maternal thyroid disease and babies born with heart, brain, and kidney defects(509c). Levels of recurrent abortions in a population with positive levels of thyroid antibodies in one study were 40%, 5 times the normal rate(511). Hypothyroidism is a well documented risk factor in spontaneous abortions and infertility(9). Another study of pregnant women who suffer from hypothyroidism (underactive thyroid) found a four-times greater risk for miscarriage during the second trimester than those who don’t, and women with untreated thyroid deficiency were four-times more likely to have a child with a developmental disabilities and lower I.Q. (509). The American Assoc. of Clinical Endocrinologists advises that all women considering becoming pregnant should get a serum thyrotropin test so that hypothyroidism can be diagnosed and treated early(558).

Mercury blocks thyroid hormone production by occupying iodine binding sites and inhibiting hormone action even when the measured thyroid level appears to be in proper range(390,35ab). The thyroid and hypothalamus regulate body temperature and many metabolic processes including enzymatic processes that when inhibited result in higher dental decay(35) . Mercury damage thus commonly results in poor bodily temperature control, in addition to many problems caused by hormonal imbalances such as depression. Such hormonal secretions are affected at levels of mercury exposure much lower than the acute toxicity effects normally tested(390,50,84), as previously confirmed by hormonal/reproductive problems in animal populations(104,381c,50d). Mercury also damages the blood brain barrier and facilitates penetration of the brain by other toxic metals and substances(311). Thyroid imbalances, which are documented to be commonly caused by mercury (369,382,459,35,50,91), have been found to play a major role in chronic heart conditions such as clogged arteries, mycardial infarction, and chronic heart failure(510).

Mercury can have significant effects on thyroid function even though the main hormone levels remain in the normal range, so the usual thyroid tests are not adequate in such cases. Prenatal methylmercury exposure severely affects the activity of selenoenzymes, including glutathione peroxidase (GPx) and 5-iodothyronine deiodinases(5-Di and 5'-DI) in the fetal brain, even though thyroxine(T4) levels are normal(390e). Gpx activity is severely inhibited, while 5-DI levels are decreased and 5'-DI increased in the fetal brain, similar to hypothyroidism. Thus normal thyroid tests will not pick up this condition.

The pituitary gland controls many of the body’s endocrine system functions and secretes hormones that control most bodily processes, including the immune system and reproductive systems. One study found mercury levels in the pituitary gland ranged from 6.3 to 77 ppb(85), while another(348) found the mean level to be 30ppb- levels found to be neurotoxic and cytotoxic in animal studies. Some of the effect on depression is related to mercury’s effect of reducing the level of posterior pituitary hormone(oxytocin). Low levels of pituitary function are associated with depression and suicidal thoughts, and appear to be a major factor in suicide of teenagers and other vulnerable groups. The pituitary glands of a group of dentists had 800 times more mercury than controls(99). This may explain why dentists have much higher levels of emotional problems, depression, suicide,etc(Section VIII.). Amalgam fillings, nickel and gold crowns are major factors in reducing pituitary function(35,50,369,etc.). Supplementary oxytocin extract has been found to alleviate many of these mood problems(35), along with replacement of metals in the mouth(Section VI.). The normalization of pituitary function also often normalizes menstrual cycle problems, endometriosis, and increases fertility(9,35).

The thymus gland plays a significant part in the establishment of the immune system and lymphatic system from the 12^th week of gestation until puberty. Inhibition of thymus function can thus affect proper development of the immune and lymphatic systems. Lymphocyte differentiation, maturation and peripheral functions are affected by the thymic protein hormone thymulin. Mercury at very low concentrations has been seen to impair some lymphocytic functions causing subclinical manifestations in exposed workers. Animal studies have shown mercury significantly inhibits thymulin production at very low micromolar levels of exposure(513a). The metal allergens mercuric chloride and nickel sulfate were found to stimulate DNA synthesis of both immature and mature thymocytes at low levels of exposure, so chronic exposure can have long term effects(513b). Also, micromolar levels of mercuric ions specifically blocked synthesis of ribosomal RNA, causing fibrillarin relocation from the nucleolus to the nucleoplasm in epithelial cells as a consequence of the blockade of ribosomal RNA synthesis. This appears to be a factor in deregulation of basic cellular events and in autoimmunity caused by mercury. There were specific immunotoxic and biochemical alterations in lymphoid organs of mice treated at the lower doses of mercury. The immunological defects were consistent with altered T-cell function as evidenced by decreases in both T-cell mitogen and mixed leukocyte responses. There was a particular association between the T-cell defects and inhibition of thymic pyruvate kinase, the rate-limiting enzyme for glycolysis(513c). Pyruvate and glycolysis problems are often seen in mercury toxic children being treated for autism(409). L-arginine restored thymulin activity, TEC proliferation, NKT cytotoxicity, cytokine profiles and nitrite and nitrate plasma levels both in vivo and in vitro(513a).

4. Mercury’s biochemical damage at the cellular level include DNA damage, inhibition of DNA and RNA synthesis(4,38,41,42,114,142,175,197,272,296,305,392/149); alteration of protein structure (33,111,114,194,252/114); alteration of the transport of calcium(333,43,96,254,329,432); inhibition of glucose transport(338,254), and of enzyme function and other essential nutrient transport (96,198,254,258,263,264,338,339,347,410-412); induction of free radical formation(13,54,496), depletion of cellular glutathione(necessary for detoxification processes) (111,126), inhibition of glutathione peroxidase enzyme(13,258,496), endothelial cell damage(202), abnormal migration of neurons in the cerebral cortex(149), and immune system damage (34,38,111,194, 226,252,272,316,325,355).

Part of the toxic effects of mercury,cadmium, lead, etc. are through their replacing essential minerals such as zinc at their sites in enzymes, disabling the necessary enzymatic processes.

There has been a huge increase in the incidence of degenerative neurological conditions in virtually all Western countries over the last 2 decades(574). The increase in Alzheimer’s has been over 300% while the increase in Parkinson’s and other motor neuron disease has been over 50%. The primary cause appears to be increased exposures to toxic pollutants(574).

Oxidative stress and reactive oxygen species(ROS) have been implicated as major factors in neurological disorders including stroke, PD, MS, Alzheimer’s, ALS, MND,FM,CFS, etc. (13,35c,56,84,98,145,169,207b,258,424,442-444,453,462,496). Mercury induced lipid peroxidation has been found to be a major factor in mercury’s neurotoxicity, along with leading to decreased levels of glutathione peroxidation and superoxide dismustase(SOD)(13,254,489,494-496,577). Metalloprotein(MT) are involved in metals transport and detoxification(442,464). Mercury inhibits sulfur ligands in MT and in the case of intestinal cell membranes inactivates MT that normally bind cuprous ions(477), thus allowing buildup of copper to toxic levels in many and malfunction of the Zn/Cu SOD function. Exposure to mercury results in changes in metalloprotein compounds that have genetic effects, having both structural and catalytic effects on gene expression(114,241,296,442,464,477,495). Some of the processes affected by such MT control of genes include cellular respiration, metabolism, enzymatic processes, metal-specific homeostasis, and adrenal stress response systems. Significant physiological changes occur when metal ion concentrations exceed threshold levels. Such MT formation also appears to have a relation to autoimmune reactions in significant numbers of people (114,60,313,342,369,442,464). Of a population of over 3000 tested by the immune lymphocyte reactivity test(MELISA,60,342), 22% tested positive for inorganic mercury and 8% for methyl mercury .

Programmed cell death(apoptosis) is documented to the a major factor in degenerative

neurological conditions like ALS, Alzheimer’s, MS, Parkinson’s, etc. Some of the factors documented to be involved in apoptosis of neurons and immune cells include inducement of the inflamatory cytokine Tumor Necrosis Factor-alpha(TNFa) (126), reactive oxygen species and oxidative stress(13,43b,56a,296b), reduced glutathione levels(56,126a,111a), inhibition of protein kinase C(43), nitric oxide and peroxynitrite toxicity(43a), excitotoxicity and idation(490,496,521,524), excess free cysteine levels(56d,111a),excess glutamate toxicity(13b, 416e), excess dopamine toxicity (56d,13a), beta-amyloid generation(462), increased calcium influx toxicity (416e,296b,333,432,462c,507)and DNA fragmentation(296) and mitochondrial membrane dysfunction(56d,416e,51a).

TNFa(tumor necrosis factor-alpha) is a cytokine that controls a wide range of immune

cell response in mammals, including cell death(apoptosis). This process is involved in inflamatory and degenerative neurological conditions like ALS, MS, Parkinson’s, rheumatoid arthritis, etc. Cell signaling mechanisms like sphingolipids are part of the control mechansim for the TNFa apoptosis mechanism(126a). Gluthathione is an amino acid that is a normal cellular mechanism for controlling apoptosis. When glutathione is depleted in the brain, reactive oxidative species increased, and CNS and cell signaling mechinsisms are disrupted by toxic exposures such as mercury, neuronal cell apoptosis results and neurological damage. Mercury has been shown to induce TNFa and deplete glutathione, causing inflamatory effects and cellular apoptosis in neuronal and immune cells(126b,126c).

Another neurological effect of mercury that occurs at very low levels is inhibition of nerve growth factors, for which deficiencies result in nerve degeneration. Mercury vapor is lipid soluble and has an affinity for red blood cells and CNS cells(21a). Only a few micrograms of mercury severely disturb cellular function and inhibits nerve growth (175,147,226,255,305,149). Prenatal or neonatal exposures have been found to have life long effects on nerve function and susceptibility to toxic effects. Prenatal mercury vapor exposure that results in levels of only 4 parts per billion in newborn rat brains was found to cause decreases in nerve growth factor and other effects(305). This is a level that is common in the population with several amalgam fillings or other exposures(500). Insulin-like-growth factor I (IGF-I) are positively correlated with growth hormone levels and have been found to be the best easily measured marker for levels of growth hormone, but males have been found more responsive to this factor than women(497). IGF-I controls the survival of spinal motor neurons affected in ALS during development as well as later in life(497,498). IGF-I and insulin levels have been found to be reduced in ALS patients with evidence this is a factor in ALS(497,498). Several clinical trials have found IGF-I treatment is effective at reducing the damage and slowing the progression of ALS and Alzheimer’s with no medically important adverse effects(498). It has also been found that in chronically ill patients the levels of pituitary and thyroid hormones that control many bodily processes are low, and that supplementing both thyrotropin-releasing hormone and growth control hormone is more effective at increasing all of these hormone levels in the patient(499).

(11) A direct mechanism involving mercury’s inhibition of cellular enzymatic processes by binding with the hydroxyl radical(SH) in amino acids appears to be a major part of the connection to allergic/immune reactive conditions such as autism(408-414,439,464,468,476,33,160,251c), schizophrenia(409,410), lupus (234,330,331,468,260e), Scleroderma(468), eczema and psoriasis (323,342,385,419,455,33), and allergies (26,46,60,95,132,152,156,271,313,330,331, 445,446,468). For example mercury has been found to strongly inhibit the activity of dipeptyl peptidase (DPP IV) which is required in the digestion of the milk protein casein(411,412) as well as of xanthine oxidase(439). Studies involving a large sample of autistic and schizophrenic patients found that over 90 % of those tested had high levels of the milk protein beta-casomorphin-7 in their blood and urine and defective enzymatic processes for digesting milk protein(410). Elimination of milk products from the diet has been found to improve the condition. Such populations have also been found to have high levels of mercury and to recover after mercury detox(413,60,313). As mercury levels are reduced the protein binding is reduced and improvement in the enzymatic process occurs. Additional cellular level enzymatic effects of mercury’s binding with proteins include blockage of sulfur oxidation processes(33,114,194,412), enzymatic processes involving vitamins B6 and B12(418), effects on the cytochrome-C energy processes (43,84,232,338c,35), along with mercury’s adverse effects on cellular mineral levels of calcium, magnesium, zinc, and lithium (43,96,119,198,333, 386,427,432,38). And along with these blockages of cellular enzymatic processes, mercury has been found to cause additional neurological and immune system effects in many through immune/autoimmune reactions (60,203d,313,314,21). Most doctors treating such conditions also usually recommend supplementing the deficient essential minerals previously noted that mercury affects, often obtaining a hair element test to determine imbalances and needs(386,484).

But the effect on the immune system of exposure to various toxic substances such as toxic metals and environmental pollutants has also been found to have additive or synergistic effects and to be a factor in increasing eczema, allergies, asthma, and sensitivity to other lesser allergens. Most of the children tested for toxic exposures have found high or reactive levels of other toxic metals, and organochlorine compounds (413,313,415). Much mercury in saliva and the brain is also organic (220,272,506), since mouth bacteria and other organisms in the body methylate inorganic mercury to organic mercury(51,81,225,503b,506,512). Studies and clinical tests have found amalgam to be the largest source of methyl mercury in most people(506,220,79,386,etc.). Bacteria also oxidize mercury vapor to the water soluble, ionic form Hg(II) (431). A clinical study found that methyl mercury in saliva is significantly higher in those with amalgam fillings than those without, and correlated with the number of amalgam fillings(506). The average level of methyl mercury in the blood of a group with amalgam was more than 4 times that of groups without amalgam or that had amalgam replced. Total mercury in those with amalgams was over 10 times that of those without amalgam. Other studies have found similar results(512,79,etc.).

5. Because of the extreme toxicity of mercury, only ½ gram is required to contaminate a 10 acre lake to the extent that a health warning would be issued by the government to not eat the fish(151,160). Over half the rivers and lakes in Florida have such health warnings banning or limiting eating of fish, and most other states and 4 Canadian provinces have similar health warnings(2). Wisconsin has fish consumption warnings for over 250 lakes and rivers and Minnesota even more, as part of the total of over 50,000 such lakes with warnings(2)

Over 30 % of all U.S. lakes have mercury health warnings and 15% of all U.S. river miles. All Great Lakes as well as many coastal bays and estuaries and large numbers of salt water fish carry similar health warnings.. Some wading birds and Florida panthers that eat birds and animals that eat fish containing very low levels of mercury(about 1part per million) have died from chronic mercury poisoning (104,160,2). Since mercury is an estrogenic chemical and reproductive toxin, themajority of the rest cannot reproduce. The average male Florida panther has higher estrogen levels than females, due to the estrogenic properties of mercury(105,160). Similar is true of some other animals at the top of the food chain like alligators, polar bears, minks, seals, beluga and orca whales, etc. , which are affected by mercury and other hormone disrupting chemicals.(105,533)

6. Mercury accumulates in the pituitary glands, ovaries, testes, and prostate gland(35,99,9 19,20,25,85,273). In addition to having estrogenic effects, mercury has other documented hormonal effects including effects on the reproductive system resulting in lowered sperm counts, defective sperm cells, damaged DNA, aberrant chromosome numbers rather than the normal 46, chromosome breaks, and lowered testosterone levels in males and menstrual disturbances and infertility in women(4,9,10,23,31,37,105,146,159,395,433,27,35,38); and increased neurological problems related to lowered levels of neurotransmitters dopamine, serotonin, noreprenephrine, and acetylcholinesterase (35,38,104,107,125,140,141,175,251,254, 275,288,290,296,305,365,367,372,381,432,451,465,412). The reduced neurotransmitter levels in those with amalgam appear to be a factor encouraging smoking since nicotine increases these neurotransmitter levels and a much higher percentage of those with amalgam smoke than in those without amalgam(141).

Some of the effect on depression is related to mercury’s effect of reducing the level of posterior pituitary hormone(oxytocin). Low levels of pituitary function are associated with depression and suicidal thoughts, and appear to be a major factor in suicide of teenagers and other vulnerable groups. The pituitary glands of a group of dentists had 800 times more mercury than controls(99). This may explain why dentists have much higher levels of emotional problems, depression, suicide,etc(Section VIII.). Amalgam fillings, nickel and gold crowns are major factors in reducing pituitary function(35,50,369,etc.). Nickel has also been found to accumulate in the prostate and be related to prostate cancer(581). Supplementary oxytocin extract has been found to alleviate many of these mood problems(35), along with replacement of metals in the mouth(Section VI.). The normalization of pituitary function also often normalizes menstrual cycle problems, endometriosis, and increases fertility(35,9).

7. An average amalgam filling contains over ½ gram of mercury, and the average adult had at least 5 grams of mercury in fillings(unless most has vaporized). Mercury in solid form is not stable, having low pressure and being subject to galvanic action with other metals in an oral environment(182,192,292,348,349,525), so that within 10 years up to half has been found to have been transferred to the body of the host(18,34,35,182, & section III). In patients with galvanic cell in their oral cavity we found decreased levels of antiinflamatory markers, such as secretory IgA, IgA 1, IgA 2, and lysozyme, and increased levels of the proinflammatory marker albumin (192i).

The amount of mercury released by a gold alloy bridge over amalgam over a 10 year period was measured to be approx. 101 milligrams(mg)(60% of total) or 30 micrograms(ug) per day(18).

8. Elemental mercury vapor is more rapidly transmitted throughout the body than most other forms of mercury and has more much toxic effects on the CNS and other parts of the body than inorganic mercury due to its much greater capacity to cross cell membranes, according to the World Health Organization and other studies (38,82,183,287,360,376e,21a, section III). Mercury vapor rapidly crosses the blood-brain barrier(14,85,311) and placenta of pregnant women (20,22-24,27,38,105, 162,186,231,281,287,304,308, 311,361) Developmental, learning, and behavioral effects have been found from mercury vapor at much lower levels than for exposure to methyl mercury(287,304). Similarly for inhibition of some essential cellular processes(333,338,329).

9. Running shoes with ½ gram of mercury in the heels were banned by several states, because the amount of mercury was considered dangerous to public health and created a serious disposal problem. Mercury from dental offices and human waste from people with amalgam fillings has much higher levels and is a major source of mercury in Florida and U.S. waters. Nationwide the dental industry is the third largest user of mercury, using over 45 tons of mercury per year(548,549), and most of this mercury eventually ends up in the environment. Amalgam from dental offices is by far the largest contributor of mercury into sewers and sewer plants(548,549), with mercury from replaced amalgam fillings and crown bases the largest source. One study found dental offices discharge into waste water between 65 and 842 milligrams per dentist per day(231), amounting to several hundred grams per year per office. This is in addition to air emissions. In Canada the annual amount discharged is about 2 tons per year(28), with portions ending up in waters/fish, some in landfills and cropland, and in air emissions. When amalgam fillings are removed by standard practice methods using primary and secondary solids collectors, approximately 60% of the amalgam metals by weight end up in sewer effluent(547b). As much as 10% of prepared new amalgam becomes waste. This mercury also accumulates in building sewer pipes and septic tanks or drain fields where used, creating toxic liabilities. The recently enacted regulations on dental office waste in Canada are expected to reduce emissions by at least 63% by 2005, compared to 2000(547). Mercury excreted into sewers by those with amalgam fillings was found by government agencies to be the second largest source of mercury in sewers(548,549,553). In a Finnish study, over 20 % of those with amalgam excrete so much to home sewers that the EEU standard for mercury in sewers(50 ug/L) is exceeded(553). The percentage exceeding the standard doubled for each additional 10 amalgam surfaces.

Additionally cremation of those with amalgam fillings adds to air emissions and deposition onto land and lakes. A study in Switzerland found that in that small country, cremation released over 65 kilograms of mercury per year as emissions, often exceeding site air mercury standards(420), while another Swiss study found mercury levels during cremation of a person with amalgam fillings as high as 200 micrograms per cubic meter(considerably higher than U.S. mercury standards). The amount of mercury in the mouth of a person with fillings was on average 2.5 grams, enough to contaminate 5 ten acre lakes to the extent there would be dangerous levels in fish(151). A Japanese study estimated mercury emissions from a small crematorium there as 26 grams per day(421). A study in Sweden found significant occupational and environmental exposures at crematoria, and since the requirement to install selenium filters mercury emission levels in crematoria have been reduced 85%(422).

10. Studies have found that levels of exposure to the toxic metals mercury, cadmium, and lead have major effects on classroom behavior, learning ability, and also in mental patients and criminals behavior(3,160).

Studies have found that both genetic susceptibility and environmental exposures are a factor in xenobiotic related effects and disease propagation(21d,7e,11a,230b,etc.). Large numbers of animal studies have documented that genetically susceptible strains are more affected by xenobiotic exposures than less susceptible strains (234,336,425,526,etc.). Some genetic types are susceptible to mercury induced autoimmunity and some are resistant and thus much less affected(234,336,425,383,21d). Studies found that mercury causes or accelerates various systemic conditions in a strain dependent manner, and that lower levels of exposure adversely affect some strains but not others, including inducing of autoimmunity. Also when a condition has been initiated and exposure levels decline, autoimmune antibodies also decline in animals or humans(342,369,405,233,234d). One genetic factor in Hg induced autoimmunity is major histocompatibility complex(MHC) linked. Both immune cell type Th1 and Th2 cytokine responses are involved in autoimmunity(425c). Mercury has been found to affect both Th1 and Th2 cytokines causing an increase in inflammatory Th2 cytokines(152,181,285,404b). In the pancreas, the cells responsible for insulin production can be damaged or destroyed by the chronic high levels of cytokines, with the potential of inducing type II diabetes - even in otherwise healthy individuals with no other risk factors for diabetes(501). Mercury inhibits production of insulin and is a factor in diabetes and hypoglycemia, with significant reductions in insulin need after replacement of amalgam filings and normalizing of blood sugar(35). Diabetes incidence is increasing drastically. For individuals born in 2000, the lifetime risk of diabetes in the U.S. is 33% and over 16 million currently have diabetes(501d). Several studies have documented that lipoic acid(an antioxidant and chelator) resulted in improvement in the majority of diabetes cases it was used for, by improving glucose metabolism, increasing insulin sensitivity, and reducing nerve damage(including in diabetic neuropathy)(501e).

Another genetic difference found in animals and humans is cellular retention differences for metals related to the ability to excrete mercury(426). For example it has been found that individuals with genetic blood factor type APOE-4 do not excrete mercury readily and bioaccumulate mercury, resulting in susceptibility to chronic autoimmune conditions such as Alzheimer’s, Parkinson’s, etc. as early as age 40(437cd,577,35), whereas those with type APOE-2, which contains 2 cysteine molocules, readily excrete mercury and are less susceptible. Those with type APOE-3 are intermediate to the other 2 types. The incidence of autoimmune conditions have increased to the extent this is now one of the leading causes of death among women(450).

11. Long term occupational exposure to low levels of mercury can induce slight cognitive deficits, lability, fatigue, decreased stress tolerance, etc. Higher levels have been found to cause more serious neurological problems (119,128,160,285,457,etc.). Occupational exposure studies have found mercury impairs the body’s ability to kill Candida albicans by impairment of the lytic activity of neutrophils and myeloperoxidase in workers whose mercury excretion levels are within current safety limits(285,404,467). Such levels of mercury exposure were also found to inhibit cellular respiratory burst. A population of plant workers with average mercury excretion of 20 ug/ g creatinine was found to have long lasting impairment of neutrophil function(285,404). Another study(59) found such impairment of neutrophils decreases the body’s ability to combat viruses such as those that cause heart damage, resulting in more inflammatory damage. Another group of workers with average excretion rates of 24.7 ug/ g creatinine had long lasting increases in humoral immunological stimulation of IgG, IgA, and IgM levels. Other studies(285b,g,395) found that workers exposed at high levels at least 20 years previous(urine peak levels above 600 ug/L demonstrated significantly decreased strength, decreased coordination, increased tremor, paresthesia, decreased sensation, polyneuropathy, etc. Significant correlations between increasing urine mercury concentrations and prolonged motor and sensory distal latencies were established(285g,119e). Elemental mercury can affect both motor and sensory peripheral nerve conduction and the degree of involvement is related to time‑integrated urine mercury concentrations. Thirty percent of dentists with more than average exposure were found to have neuropathies and visuographic dysfunction compared to none in the control group(395d). Other studies have also found a connection between mercury with peripheral neuropathy and paresthesia(190,449,502,71bd,395c). Several doctors have found thiamin(B3), Vit B6, inositol, and folic acid supplementation to alleviate peripheral neuropathies, pain, tinnitus, and other neurological conditions(502)

Another study found that many of the symptoms and signs of chronic candidiasis, multiple chemical sensitivity and chronic fatigue syndromes are identical to those of chronic mercurialism and remit after removal of amalgam combined with appropriate supplementation and gave evidence to implicate amalgam as the only underlying etiologic factor that is common to all(404).

Other studies(285c) found that mercury at levels below the current occupational safety limit causes adverse effects on mood, personality, and memory- with effects on memory at very low exposure levels. More studies found that long term exposure causes increased micro nuclei in lymphocytes and significantly increased IgE levels at exposures below current safety levels(128), as well as maternal exposure being linked to mental retardation(110) and birth defects(23,35,37,38,50,142,241,361,338c/241).

III. Systemic Mercury Intake Level from Amalgam Fillings

1. The tolerable daily exposure level for mercury developed in a report for Health Canada is .014 micrograms/kilogram body weight(ug/kg) or approximately 1 ug/day for average adult(209). The U.S. EPA Health Standard for elemental mercury exposure(vapor) is 0.3 micrograms per cubic meter of air(2). The U.S. ATSDR health standard(MRL) for mercury vapor is 0.2 ug/ M ³ of air, and the MRL for methyl mercury is 0.3 ug/kg body weight/day(217). For the average adult breathing 20 M ³ of air per day, this amounts to an exposure of 4 or 6 ug/day for the 2 elemental mercury standards. The EPA health guideline for methyl mercury is 0.1 ug/kg body weight per day or 7 ug for the average adult(2), or approx. 14 ug for the ATSDR acute oral toxicicity standard. Since mercury is methylized in the body, some of both types are present in the body. The older World Health Organization(183) mercury health guideline(PTWI) is 300 ug per week total exposure or approx. 42 ug/day. The EPA drinking water standard for mercury is 2ppb(125). The upper level of mercury exposure recommended by the German Commission on Human Biomonitoring is 1 micrograms per liter in the blood(39), since adverse effects such as increases in blood pressure and cognitive effects have been documented as low as 1 ug/L cord blood, with impacts higher in low birth weight babies(308) and commonly in adults with levels below 10 ug/l(540). The FDA limit for mercury in seafood is 1 ppm, with a warning at ½ ppm (125). The Japanese government's limit for mercury contamination, 0.4 micrograms per gram(533) and studies have found adverse health effects eating fish at levels below 0.5 ppm(20,540) . EPA and several medical labs suggest health safety guideline of 1 ppm(438). The EPA safety standard for mercury in blood is 5.8 ppb(218b) and EPA has found that since the fetus normally has mercury levels 70% above that of the mother’s blood, large numbers of infants are at risk of neurological damage.

2. Mercury in the presence of other metals in the oral environment undergoes galvanic action, causing movement out of amalgam and into the oral mucosa and saliva(174,182,192,436,525,179,199). Mercury in solid form is not stable due to high volatility and evaporates continuously from amalgam fillings in the mouth, being transferred over a period of time to the host(15-19,26,31,36,79,83, 211, 182,183,199,276b,298,299,303,332,335,371). Mercury has a relatively high vapor pressure and vaporizes at room temperature. The rate of mercury volatilization is directly related to temperature so in the body it is even more volatile. The vapor saturation concentration in air of 20 milligrams of mercury per cubic meter of air is much higher than the safety limit. The ATSDR safety standard(MRL) for mercury is 0.2 micrograms of mercury per cubic meter of air.. Thus mercury readily vaporizes to above the MRL level. The daily total exposure of mercury from fillings is from 3 to 1000 micrograms per day, with the average exposure being above 10 micrograms per day and the average uptake over 5 ug/day (183,199,209,18,19,77,83, 85,100,335,352,371,etc.). (see further details continued)

A large study was carried out at the Univ. Of Tubingen Health Clinic in which the level of mercury in saliva of 20,000 persons with amalgam fillings was measured(199). The level of mercury in unstimulated saliva was found to average 11.6 ug Hg/L, with the average after chewing being 3 times this level. Several were found to have mercury levels over 1100 ug/L, 1 % had unstimulated levels over 200 ug/L, and 10 % had unstimulated mercury saliva levels of over 100 ug/L.. The level of mercury in saliva has been found to be proportional to the number of amalgam fillings, and generally was higher for those with more fillings, increasing by approximately 1.5 ug/L for each additional amalgam filling. The following table gives the average daily mercury exposure from saliva alone for those tested, based on the average levels found per number of fillings and using daily saliva volumes of 890 ml for unstimulated saliva flow and 80 ml for stimulated flow (estimated from measurements made in the study and comparisons to other studies). It also gives the 84th percentile mercury exposure from saliva for the 20,000 tested by number of fillings. Note that 16% of all of those tested with 4 amalgam fillings had daily exposure from their amalgam fillings of over 17 ug per day, and even more so for those with more than 4 fillings.

Table: Average daily mercury exposure in saliva by number of amalgam fillings(199)

Number of fillings: 4 5 6 7 8 9 10 11 12 13 14 15 16

Av. Daily Hg(ug) 6.5 8 9.5 11 12.4 14 15.4 16.9 18.3 19.8 21.3 22.8 24.3

84th percentile(ug) 17 23.5 26 30.5 35 41.5 43.8 48.6 50.3 46.7 56.6 61.4 64.5

Saliva tests for mercury are commonly performed in Europe, and many other studies have been carried out with generally comparable results(292,315,79,9b,335,179,317,352). Another large German study(352) found significantly higher levels than the study summarized here, with some with exposure levels over 1000 ug/day. These studies found that the amount of mercury in saliva increased about 1.5 to 2.5 micrograms for each additional amalgam filling(199,352). Some of the variability in these studies might be due to the fact that a more accurate measure of exposure such as amalgam surfaces augmented by also counting the number of metal crowns over amalgam. Metal crowns over amalgam have been found to produce as much exposure as an amalgam filling, due to galvanic currents in mixed metals. Three studies that looked at a population with more than 12 fillings found generally higher levels than this study, with average mercury level in unstimulated saliva of 29 ug/L(18), 32.7 ug/L (292c), and 175 ug/day(352). The average for those with 4 or less fillings was 8 ug/L(18). While it will be seen that there is a significant correlation between exposure levels and number of amalgam surfaces and exposure generally increases as number of fillings increases, there is considerable variability for a given number of fillings. Some of the factors that will be seen to influence this variability include composition of the amalgam, whether person chews gum or drinks hot liquids, bruxism, oral environmental factors such as acidity, type of tooth paste used, etc. Chewing gum or drinking hot liquids or use of bleaching products to whiten teeth can result in 10 to 100 times normal levels of mercury exposure from amalgams during that period(15,35,136,258).

The Tubingen study did not assess the significant exposure route of intraoral air and lungs. One study that looked at this estimated a daily average burden of 20 ug from ionized mercury from amalgam fillings absorbed through the lungs(191), while a Norwegian study found the average level in oral air to be 0.8 ug/M3(176). Another study at a Swedish University(335) measured intraoral air mercury levels from fillings of from 20 to 125 ug per day, for persons with from 18 to 82 filling surfaces. Other studies found similar results(83,95), and some individuals have been found to have intraoral air mercury levels above 400 ug/ M3 (319). Most of those whose intraoral air mercury levels were measured exceeded U.S. Gov’t health guidelines for workplace exposure(2). The German workplace mercury limit is even lower than the U.S. guideline, at 1 ug/M³(258).