Blood mercury content after chewing.
“The purpose of this study was to investigate whether chewing on amalgam fillings can release enough mercury to increase the blood mercury level to 175 nmol/1.”
An epidemiologic study of the relation between symptoms of fatigue, dental amalgam and other factors.
“Fatigue has been described as a symptom of mercury toxicity. The aim of this pilot study was to investigate whether fatigue is related to the number of tooth surfaces of amalgam or to other factors. The study population was a group of 108 hospital workers who completed a self administered questionnaire including questions about fatigue in a study (1983) to determine the effects of exposure to glutaraldehyde. The 39 women who gave positive answers to one or two of the questions about fatigue were assigned cases. The referents were chosen with regard to sex, age and smoking habits among those who gave negative answers to both questions. Information about the number of surfaces of amalgam was received from dentists. Analysis showed that the cases and referents were not significantly different in terms of the mean number of surfaces of amalgam. There was a significant positive relation between the number of surfaces of amalgam and age as well as smoking habits. A significant positive relation was also found between symptoms of fatigue and psychosocial factors and the frequency of sick-leave in respiratory diseases. In conclusion other factors rather than the release of mercury from dental amalgam could explain the symptoms of fatigue.”
Epidemiologic study on the association between body burden mercury level and idiopathic Parkinson’s disease.
“A case-control study was conducted among the multiethnic population of Singapore to test the hypothesis that a high level of body burden mercury is associated with an increased risk of Parkinson’s disease (PD). Selected factors investigated that could contribute to the body burden of mercury included dietary fish intake, ethnic over-the-counter medications, occupational exposures and possession of dental amalgam fillings. Detailed interviews were completed in 54 cases of idiopathic PD and 95 hospital-based controls, matched for age, sex and ethnicity, between July 1985 and July 1987. After adjusting for potential confounding factors, including dietary fish intake, medications, smoking and alcohol consumption, there was clear monotonic dose-response association between PD and blood mercury levels. The odds ratios (OR) and 95% confidence intervals (CI) for the approximate subject tertiles based upon blood mercury levels were 8.5 (CI = 2.2-33.2) and 9.4 (CI = 2.5-35.9), relative to the tertile with lowest blood mercury levels (less than 5.8 ng Hg/ml). Similar associations were revealed using scalp hair and urinary mercury levels. However, only the comparisons between the highest and lowest tertiles were statistically different from unity (p less than 0.05). When the body burden mercury indicators were mutually adjusted in addition to the four confounding factors, blood and urinary mercury levels showed ORs of 21.00 and 18.65, respectively. These ORs were statistically different from unity (p less than 0.05, 2-sided test). After adjustment, scalp hair mercury was shown to be a poor predictor of PD risk.”
Aberrant guanosine triphosphate-beta-tubulin interaction in Alzheimer’s disease.
“Guanosine triphosphate (GTP) is an absolute requirement for tubulin polymerization in situ. The nucleotide photoaffinity probe 8-azidoguanosine 5′-triphosphate (8N3GTP) has been shown to be a biological mimic of GTP in this system and, also, an effective active site probe of the exchangeable GTP binding site. Using [32P]8N3GTP we demonstrate that the exchangeable GTP site of the beta subunit of tubulin is available to added guanine nucleotide in normal aged brain homogenates, whereas it is variably unavailable in Alzheimer’s diseased brain. Inability of 8N3GTP to photolabel beta tubulin appears to be associated with neurofibrillary tangle density. These results support the hypothesis that microtubule formation is abnormal in brains affected by Alzheimer’s disease.”
Pregnancy outcome in women working as dentists, dental assistants or dental technicians.
“Pregnancy outcome in women with work in dentistry was studied using various central health registries. A total of 8157 infants born of dentists, dental assistants, or dental technicians in 1976 or 1982-1986 in Sweden were studied with respect to perinatal survival, low birthweight, and malformations and compared with all births. The only deviating finding was that of a significantly low perinatal death rate. Specifically, no increase in a risk for spina bifida was seen and the upper 95% confidence limit for the risk ratio was 2.1. A study was also made of hospitalized spontaneous abortions in women with these occupations in the years 1980-1981. No significant deviations from expected values were found. In a small study of only 78 such pregnancies in 1964-1965, no increase in spontaneous abortion rate was seen. Only one infant was malformed (anencephaly): both its parents worked as dental technicians. None of the mothers of 220 infants with a neural tube defect born in 1965-1967 in Sweden was a dentist. We find no indications that this occupation represents a significant reproduction hazard at the present time in Sweden.”
Accumulation of methylmercury and inorganic mercury in the brain.
“Differences in metabolism between different mercury species are well recognized. Conclusions that only a minor demethylation of methylmercury takes place in the brain are based primarily on results from short term studies. Results from a number of studies on humans exposed for many years to methylmercury have shown high concentrations of inorganic mercury in the brain in relation to total mercury. Similar evidence is available from studies on monkeys exposed for several years to methylmercury. The results indicate that a significant accumulation of inorganic mercury takes place with time despite the fact that the demethylation rate is slow. Differences in biological halftimes between different mercury species will explain the results. Some data do still need confirmation using different analytical methods. There is reason to believe that the one-compartment model for methyl mercury cannot be used without reservations. Inorganic mercury has a complicated metabolism. After exposure to metallic mercury vapor, inorganic mercury, probably bound to selenium, accumulates in the brain. A fraction of the mercury is excreted, with a long biological halftime. Studies on rats and monkeys indicate that inorganic mercury penetrates the blood-brain barrier only to a very limited extent.”
The contribution of dental amalgam to mercury in blood.
“We determined the exposure to mercury from dental amalgam by comparison of blood levels of mercury before and after removal of all amalgams from ten subjects. Baseline concentrations of mercury in whole blood were measured weekly for four to 18 weeks (median = 6.6 weeks) prior to removal. All amalgams were removed in a single appointment. The subjects had an average of 14 surfaces of amalgam, seven of which were occlusal surfaces. Weekly blood sampling was continued for five to 18 weeks (median = 7.6 weeks) after the amalgams were removed. The mean baseline concentration of total mercury in whole blood of the ten subjects was 2.18 (SD = 0.90) ng Hg/mL before the amalgams were removed. The baseline mercury levels were related to the number of amalgam surfaces. The linear correlation coefficient was 0.724 with number of occlusal surfaces, and 0.433 with total number of surfaces. After removal of the amalgams, nine of the ten subjects exhibited a statistically significant decrease in blood mercury at the 95% level of confidence. The mean decrease in mercury was 1.13 (SD = 0.60) ng Hg/mL. The half-time for elimination of mercury from blood after amalgam removal was 30.2 (SD = 5.8) days. Removal of the amalgams provided an additional exposure of 1.46 (SD = 1.17) ng Hg/mL that was rapidly cleared from the blood with a half-time of 2.9 days. The daily intake of mercury from amalgam in the subjects was estimated to be at least 1.3 micrograms.”
The relationship between mercury from dental amalgam and mental health.
“The findings presented here suggest that mercury poisoning from dental amalgam may play a role in the etiology of mental illness. Comparisons between subjects with and without amalgam showed significant differences in subjective reports of mental health. Subjects who had amalgams removed reported that symptoms of mental illness lessened or disappeared after removal. The data suggest that inorganic mercury poisoning from dental amalgam does affect the mind and emotions.”
Cytotoxicity and mutagenicity of ophthalmic solution preservatives and UVA radiation in L5178Y cells.
“Four chemical preservatives commonly used in ophthalmic solutions were tested for their toxic and mutagenic potential in mouse lymphoma cells with and without exposure of the cells to ultraviolet A (UVA) radiation. The preservatives tested were benzalkonium chloride (BAK), chlorhexidine, thimerosal and ethylenediaminetetraacetic acid (EDTA). Cell survival and mutagenesis were measured using the L5178Y mouse lymphoma (TK +/-) system. Cells were exposed to varying amounts of preservatives for 1 h at 37 degrees C, and then aliquots were irradiated with UVA radiation (during the exposure to preservative). Cells were then assayed for survival, and for mutagenesis at the thymidine kinase (TK) locus. In concentrations commonly found in ophthalmic solutions, BAK, chlorhexidine, and thimerosal were toxic to cells, and thimerosal was slightly mutagenic. When cells were exposed to preservative and UVA radiation, chlorhexidine was mutagenic and the mutagenic activity of thimerosal was enhanced.”
Relation between mercury and selenium in pituitary glands of dental staff.
“Analyses of mercury concentration have shown high concentrations of mercury in the pituitary glands of dental staff. By contrast with mercury (Hg), selenium (Se) is an essential trace element. After simultaneous administration to rats, Hg and Se have been reported to be associated with a single protein fraction in the plasma.”