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Mercury in dental-filling materials - an updated risk analysis in environmental medical terms PDF Print E-mail
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Sunday, 01 September 2002 00:00
“Mercury is thus a multipotent cytotoxin that intervenes in the primary processes of the cell. This creates scope for a broad spectrum of possible side-effects. The analysis performed in 1997 identified the following health risks from mercury in dental fillings:

o Risk of impairment in the functions of the central nervous system.
o Risk of impairment in kidney function.
o Risk of impairment in the immune system.
o Risk of impairment in foetal development, especially development of the nervous system.”

“Mice exposed to mercury vapour, at 0.5 mg/m3 for two hours, showed an elevated mercury concentration in motor neurons in the spine and signs of oxidative damage to DNA (Pamphlett et al. 1998).”

“In determining mercury concentrations in amalgam bearers. saliva, Pizzichini et al. (2001, 2002) found a significant correlation between mercury in saliva and the number of amalgam fillings in both men and women.”

“Exposure to mercury vapour in rat (Warfvinge et al. 1992), mouse (Warfvinge 1995) and monkey (Warfvinge et al. 1994; Warfvinge 2000) causes accumulation of mercury in the brain and spinal cord. Mercury was often concentrated in neurons, especially motor neurons and astroglia cells.”

“Early 2002 saw the publication of a meta-analysis of 44 epidemiological studies of populations that are occupationally exposed to mercury vapour. Twelve of these studies were included in the analysis, which comprised 686 exposed persons and 579 controls. In nine neuropsychological performance parameters, statistically significant differences between exposed persons and controls were found…”

“In an Italian multicentre study of 122 workers exposed to mercury vapour and 196 controls, a statistically significant decline in motor performance…”

“In a cross-section study in Scotland, 180 dentists were compared with 180 academics at Scottish universities. Kidney disease was found to be ten times more common among the dentists (6.5%) than in the controls.”

“Ellingsen et al. (2000b) reported finding impaired thyroid function in a group of 47 chloralkali workers, whom they compared with 47 controls. The exposed workers showed a statistically significant rise in reverse T3 (rT3) - a rise that was dose-related.”

“This survey supports the hypothesis that, among those who believe themselves to be suffering as a result of amalgam, the true cause is not always amalgam. However, it does not rule out the possibility that amalgam influence can be found in some of these persons. The diagnoses mentioned in this study include impaired thyroid function, oral lichen, kidney disease, fatigue, vertigo, somatisation tendency, depression and anxiety - all of which are symptoms that may be associated with mercury exposure.”

“A Swiss dentist followed up 75 of the 90 patients he had treated with amalgam removal according to the patients' own wishes. All the patients had psychoneurological symptoms or muscular and joint pains of various kinds. Sixty-eight per cent of the patients felt that they were much better at the time of their annual check-ups following the removal. Another 12 per cent felt better, 9 per cent were slightly better, 7 per cent were unchanged and one of the patients felt worse after the removal (Engel 1998).”

“In a similar Swedish questionnaire survey comprising 445 patients of one dentist, the patients' amalgam fillings were removed because of prolonged, unexplained ailments. Here, the health of 80 per cent of the patients whose fillings had been removed was found to be good or better, while that of 11 per cent was unchanged and 9 per cent felt that it had deteriorated or were doubtful. More than half the patients stated that they had experienced symptoms in connection with having their fillings removed. These symptoms often began after a few days and commonly lasted about a week (Strömberg and Langworth 1998).”

“Not infrequently, progress in research raises more questions than it answers. Since 1997, three new health risks have emerged that, with reasonable suspicion, may conceivably be attributed to mercury from amalgam. These hazards involve influence on the retina of the eye, testicle function and thyroid function.”

“The 1997 risk analysis assumed that the minimum exposure level that gives rise to demonstrable impairment of the nervous system is represented by urinary secretion of mercury at roughly 50 µg/l. Subsequent research findings have shown that influence arises at considerably lower exposure levels. There is scientific evidence for influence from mercury concentrations in urine of some 25 µg/l, and from even lower levels.”

“The risk of influence on foetal development was pointed out in the 1997 risk analysis. This is not contradicted by more recent results that may suggest an elevated risk, among women exposed to mercury in the course of their work, of giving birth to babies who are small for their gestational age. In addition, there are experiments on animals indicating that one expected effect of exposure to low doses of mercury vapour is inhibition of brain development. In these experiments, this inhibition resulted in reduced cognitive and motor capacity. Such inhibition of brain development falls within the normal range in the population.”

“The risk of inhibition of brain development during the foetal stage and early childhood is obvious. This hazard is a contraindication for amalgam fillings in children and women of fertile age, until a quantification of the risk prompts a different assessment.”

“The clinical studies of how mercury vapour influences the immune system show clearly that effects can be demonstrated down to dose levels corresponding to exposure to amalgam. The clinical significance of these effects, on the other hand, is unclear.”

“Published surveys of the association between amalgam and multiple sclerosis are "of limited sensitivity, but appear to rule out amalgam as a major aetiological factor in the development of MS.”

“Experimental data prompt the question of whether removing amalgam in the event of autoimmune diseases is justified. No general reply to this question can be given; instead, in the current situation the circumstances must be weighed up in each individual case. Nevertheless, it would seem imperative for clinicians to bear this option in mind. The same applies to parasitic diseases, such as malaria.”

“Over the past five-year period, another survey has emerged that shows an elevated risk of developing kidney disease among those who are occupationally exposed to mercury. This observation was made on a group of dentists whose exposure was fairly low. The survey confirms the findings of earlier surveys.”

“There are strong indications of a gender difference in terms of mercury metabolism in data from animal experiments and in clinical observations. Information on what this may entail regarding differences in sensitivity to mercury exposure is entirely lacking. This is a fundamental shortcoming that invalidates every risk analysis.”

“In purely theoretical terms, it is highly probable - verging on certainty - that individuals with genetically conditioned deviant sensitivity to mercury exist. The clinical observations referred to above support this conclusion. Diagnosis is a problem that requires further research.”

“There are no facts indicating that all those who believe that they are affected by amalgam are in fact so affected. It is therefore more probable that, for many people, the symptoms have other causes. But it is also likely that many people with side-effects from amalgam fillings are unaware of a causal connection.”

“There is no evidence that the frequency of pathological side-effects of amalgam due to genetically conditioned high sensitivity exceeds 1%. It is therefore impossible to demonstrate these states by means of epidemiological studies of representative population samples.”

“With reference to the fact that mercury is a multipotent toxin with effects on several levels of the biochemical dynamics of the cell, amalgam must be considered to be an unsuitable material for dental restoration. This is especially true since fully adequate and less toxic alternatives are available.”

“The lowest exposure, in terms of urinary mercury secretion, that has been found to give rise to a demonstrable toxic effect has fallen from 30-50 µg/l till 10-25 µg/l. Accordingly, the safety margin that it was thought existed with respect to mercury exposure from amalgam has been erased.”

“With reference to the risk of inhibiting influence on the growing brain, it is not compatible with science and well-tried experience to use amalgam fillings in children and fertile women. Every doctor and dentist should, where patients are suffering from unclear pathological states and autoimmune diseases, consider whether side-effects from mercury released from amalgam may be one contributory cause of the symptoms.”

“Removal of existing amalgam fillings should not be undertaken unless there are medical reasons for doing so. The reason is that the risk of complications from the removal may exceed the risk of side-effects from the amalgam. The risk of removal is due mainly to the fact that dental substance is drilled away, which may itself result in problems with existing teeth.”

“For medical reasons, amalgam should be eliminated in dental care as soon as possible. This will confer gains in three respects. The prevalence of side-effects from patients' mercury exposure will decline; occupational exposure to mercury can cease in dental care; and one of our largest sources of mercury in the environment can be eliminated.”

“Dental materials left in patients' mouths should be treated as drugs for administrative purposes. Accordingly, toxicological and clinical testing should be required. Reporting of side-effects should also take place according to the same norms that apply to drugs.”

Maths Berlin, "Mercury in dental-filling materials - an updated risk analysis in environmental medical terms - An overview of scientific literature published in 1997-2002 and current knowledge", The Dental Material Commission - Care and Consideration, Kv. Spektern, SE-103 33 Stockholm, Sweden, September 1, 2002, Num. 0, 
Link: http://www.dentalmaterial.gov.se


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Last Updated on Wednesday, 24 June 2009 13:00