Mercury

“When the required studies do not exist, as is the case for amalgam, the most common approach to assessing potential risk is to compare estimated chemical intake to doses considered ‘safe,’ ‘tolerable’ or of ‘minimal risk.’ This was the approach employed in the assessment commissioned by Health Canada. This approach is not new, it is used routinely in Canada as elsewhere, and it has been applied to other medical devices. The results indicate that no credible assessment of mercury exposure, and no regulatory or other reference (acceptable, tolerable, or minimal risk) dose for mercury vapour, support the continued, unlimited placement of amalgam fillings in dental patients.”

“The characterisation of risks presented by chemical exposure requires the comparison of exposures arising from a specified source (in this case, dental amalgam) to a reference dose, a dose considered acceptable, tolerable or of minimal risk. Only Richardson (1995) has provided a characterisation of risks posed by Hg exposure from dental amalgam (see Table 1) by determining the Hazard Quotient, the ratio of estimated exposure to the reference dose. When the Hazard Quotient exceeds a value of 1.0, the potential for risk exists, and that potential increases with the degree to which the Hazard Quotient exceeds 1.0 in value.”

“Seated in dentist Robert Hepps’ chair with a cavity in need of attention, you are sure to hear about the beauties of porcelain, and will probably see a gruesome video of teeth deteriorating around black metal fillings. Hepps believes porcelain fillings are healthier for teeth and–since traditional fillings are half mercury–possibly for the rest of the body. He believes patients have a right to know that, and the law is on his side.”

“OBJECTIVES:

To investigate the association between multiple sclerosis, dental caries, amalgam fillings, body mercury and lead.

DESIGN:

Matched case-control study.

SETTING:

Leicestershire in the years 1989-1990.

SUBJECTS:

Thirty-nine females with multiple sclerosis (of recent onset) were matched with 62 controls for age, sex and general practitioner.

METHODS:

Home interview of cases and controls within which there was an assessment of the DMFT index and blood and urine mercury and lead levels.

RESULTS:

The odds of being a MS case increased multiplicatively by 1.09 (95% CI 1.00, 1.18) for every additional unit of DMFT index of dental caries. This represents an odds ratio of 1.213 or a 21% increase in risk of MS in relation to dental caries in this population. There was no difference between cases and controls in the number of amalgam fillings or in body mercury or lead levels. There was a significant correlation between body mercury levels and the number of teeth filled with amalgam (controls: r = +0.430, P = 0.006, cases: r = +0.596, P = 0.001).

CONCLUSION:

There was evidence of excess dental caries among MS cases compared with the controls. This finding supports the strong geographical correlation between the two diseases. A further study of this association is recommended.”

Inflammatory cells in amalgam-associated, oral lichenoid contact lesions (OLL) were studied in 19 patients by immunocytochemistry using monoclonal antibodies. Ten of the patients displayed allergic patch test (PT) reactions to several mercury compounds and nine were negative. The immunocytochemical quantification showed a uniform composition of the inflammatory mononuclear cells in the two study groups. The number of HLA-D/DR-positive dendritic cells (P<0.001) and CD1a-positive Langerhans cells (P=0.035) was significantly lower in the PT-negative than PT-positive patients. HLA-D/DR expression on keratinocytes varied from negative to full thickness staining of the epithelium. HLA-D/DR expression in the full thickness of epithelium (3) or through the basal and spinous cell layers (2) was seen in 5 of 8 PT-positive patients, whereas none of the PT-negative patients had this staining pattern (P=0.045). These patients also showed a good clinical response after amalgam removal. Consequently, OLL may represent a true delayed hypersensitivity reaction with a trans-epithelial route of entrance of the metal haptens released from dental restorative materials.

“OBJECTIVES: We sought to investigate the possible pathogenetic role of myocardial trace elements (TE) in patients with various forms of cardiac failure.

BACKGROUND: Both myocardial TE accumulation and deficiency have been associated with the development of heart failure indistinguishable from an idiopathic dilated cardiomyopathy.

METHODS: Myocardial and muscular content of 32 TE has been assessed in biopsy samples of 13 patients (pts) with clinical, hemodynamic and histologic diagnosis of idiopathic dilated cardiomyopathy (IDCM), all without past or current exposure to TE. One muscular and one left ventricular (LV) endomyocardial specimen from each patient, drawn with metal contamination-free technique, were analyzed by neutron activation analysis and compared with 1) similar surgical samples from patients with valvular (12 pts) and ischemic (13 pts) heart disease comparable for age and degree of LV dysfunction; 2) papillary and skeletal muscle surgical biopsies from 10 pts with mitral stenosis and normal LV function, and 3) LV endomyocardial biopsies from four normal subjects.

RESULTS: A large increase (>10,000 times for mercury and antimony) of TE concentration has been observed in myocardial but not in muscular samples in all pts with IDCM. Patients with secondary cardiac dysfunction had mild increase (< or = 5 times) of myocardial TE and normal muscular TE. In particular, in pts with IDCM mean mercury concentration was 22,000 times (178,400 ng/g vs. 8 ng/g), antimony 12,000 times (19,260 ng/g vs. 1.5 ng/g), gold 11 times (26 ng/g vs. 2.3 ng/g), chromium 13 times (2,300 ng/g vs. 177 ng/g) and cobalt 4 times (86,5 ng/g vs. 20 ng/g) higher than in control subjects.

CONCLUSIONS: A large, significant increase of myocardial TE is present in IDCM but not in secondary cardiac dysfunction. The increased concentration of TE in pts with IDCM may adversely affect mitochondrial activity and myocardial metabolism and worsen cellular function.”

In 111 women with repeated miscarriages, the urinary excretion of heavy metals was determined in a challenge test with the chelating agent 2,3-dimercaptopropane-1-sulphonic acid in addition to hormonal, chromosomal, immunological and uterine investigations. The heavy metal excretion was correlated to different immunological (natural killer cells, T cell subpopulations) and hormonal (progesterone, oestradiol, prolactin, thyroid stimulating hormone) parameters. We conclude that heavy metals seem to have a negative impact on ovarian as well as on pituitary function. The heavy metal-induced immunological changes may interfere with the physiological adaptation of the immune system to the state of pregnancy with the result of a miscarriage. The observed heavy metal-induced hormonal and immunological changes may be important factors in the pathogenesis of repeated miscarriages.

“Investigators established methods for the analysis of total mercury (Hg-total), oxidized mercury and mercury bound to sulfhydryl groups (Hg-S), mercury vapor (Hg0), and mercury from amalgam particles (APs) in fecal samples. Two individuals consumed mercury as a mercury-cysteine complex mercury vapor, and mercury from amalgam particles, and the cumulative excretion of mercury in feces was followed. Investigators found that 80% of the mercury from amalgam particles and mercury bound to sulfhydryl groups was excreted, but only 40% of the mercury vapor was excreted. Speciation of mercury excreted in feces from 6 individuals with a moderate loading of amalgam fillings showed that most of the mercury originating from the fillings consisted of oxidized mercury, which was probably bound to sulfhydryl-containing compounds. The proportion of amalgam particles in fecal samples from these individuals was low, and it did not exceed 26% of the total amount of mercury excreted.”

“BACKGROUND:

The aetiology of multiple sclerosis (MS) remains poorly understood. Dental amalgams containing mercury have recently been suggested as a possible risk factor for MS.

METHODS:

In a case-control study conducted between 1991 and 1994, we interviewed a total of 143 MS patients and 128 controls, to obtain information on socio-demographic characteristics and the number of dental amalgams and the time since installation based on dentists’ records.

RESULTS:

Neither the number nor the duration of exposure to amalgams supported an increased risk of MS. After adjustment for age, sex, smoking, and education those who had more than 15 fillings had an odds ratio (OR) of 2.57 (95% CI: 0.78-8.54) compared to those who had none; for individuals whose first amalgam was inserted more than 15 years prior to the study, we found an OR of 1.34 (95% CI: 0.38-4.72).

CONCLUSIONS:

Although a suggestive elevated risk was found for those individuals with a large number of dental amalgams, and for a long period of time, the difference between cases and controls was not statistically significant.”

“This paper summarizes some recent reports on mercury release from amalgam fillings and resulting concentrations in biological fluids, development of antibiotic resistance, and kidney function. In a series of studies of subjects with amalgam fillings, mercury (Hg) levels were followed in saliva, feces, blood, plasma, and urine before and until 60 d after removal of all of the fillings. The Hg concentrations in saliva remained elevated for at least 1 wk, suggesting that dissolved Hg vapor is not the major source of mercury in mixed saliva. An absorption phase of Hg was seen in plasma during 24 h after amalgam removal. After 60 d the plasma Hg concentration was reduced to 40%, of the baseline level. The decrease per amalgam surface was 0.11 nmol/l (range 0.02 0.40). The Hg level in feces increased two orders of magnitude two days after amalgam removal. At day 60, the median Hg concentration was still slightly higher than the median value of the amalgam free control group. The resistance patterns of the oral and intestinal microflora in these subjects were also studied. In the intestinal microflora, the relative amount of intestinal microorganisms resistant to 50 microM HgCl2 peaked 7 d after removal of the amalgam fillings, with a median value per sample of 6.1%, compared to 1.3% in samples collected prior to the Hg exposure. However, no statistical differences in the resistance pattern of the oral microflora were detected between the control and the experimental groups. A number of sensitive kidney function parameters were measured 1 wk before and 1, 2, and 60 d after amalgam removal. No effects on the various kidney parameters studied were recorded. According to the conclusions of independent evaluations from different state health agencies, the release of mercury from dental amalgam does not present any non-acceptable risk to the general population.”