Mercury

“In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered.”

“In 10 healthy persons all amalgam fillings were replaced with gold inlays. Blood and urinary levels were measured on 10 occasions during a 4-month period before and a 12-month period after amalgam removal. These variables were also measured three times in 10 healthy controls. A strong statistically significant relation was found between plasma mercury values and both the total number of amalgam surfaces (r = 0.71, p = 0.0006) and the total surface area of the fillings (r = 0.73, p = 0.0004). In the immediate postremoval phase plasma mercury rose three- to four-fold, whereas the urinary and erythrocyte mercury rose about 50%. These peak values declined to the preremoval level at about 1 month. Twelve months after the removal the plasma and urinary mercury levels were significantly reduced to 50% and 25%, respectively, of the initial values for the experimental group. Apart from the significantly lower plasma selenium values 5 and 10 days after removal no significant differences were found with regard to plasma selenium or erythrocyte glutathione peroxidase either within or between the experimental and the control groups. A large number of supplementary biochemical analyses did not show any influence on organ functions or any differences between the groups before or after the amalgam removal. Amalgam fillings considerably contributed to the plasma and urinary mercury levels.”

“Recent misconceptions regarding Hg exposure from dental amalgams have been based on several questionable assumptions. The present paper reexamines earlier estimations of Hg daily dose from dental amalgam in order to elaborate and refine the mechanical and volumetric parameters of open-mouth Hg vapor sampling.”

“The mercury and selenium content in the hair of 13 ALS cases was studied by neutron activation analysis. The total mercury content of the hair was 3.70 +/- 2.73 ppm (mean +/- standard deviation) in the ALS patients as a whole, 4.46 +/- 3.16 ppm in the ALS patients from the middle of Kii Peninsula, and 2.49 +/- 1.38 ppm in the ALS patients from other region. As the comparison, mercury content was 2.43 +/- 0.79 ppm in the patients with Parkinsonism, and 2.10 +/- 1.13 ppm in the patients with multiple sclerosis (MS). The selenium content of the hair was 0.36 +/- 0.35 ppm for all ALS patients as a whole, 0.45 +/- 0.25 ppm in the ALS patients from the middle of the Kii Peninsula, and 0.21 +/- 0.47 ppm in the ALS from other region. There were no cases with higher values than mean values of control group, except one case from other regions. It is well known that the selenium decreases the toxicity of mercury in the human body. From these data mercury with low content of selenium might be one of the environmental factors which are thought to be involved in producing of ALS.”

“The difficulties associated with estimations of daily doses of inhaled mercury vapor released from dental amalgam are considerable. Existing data are often unreliable, especially if they are based on a single or a small series of samples of intra-oral concentrations of mercury vapor before, during, and after chewing stimulation. In the present paper, the aim was to obtain a more representative estimation of the daily dose of mercury vapor inhaled from amalgam fillings by measurement of amounts of mercury vapor released in the oral cavity during 24 h, under conditions that were as normal as possible. A series of measurements was carried out on each of 15 subjects, with at least nine occlusal surfaces restored with dental amalgam, and on five subjects without any amalgam restorations. The subjects had to follow a standardized schedule for 24 h, whereby they ate, drank, and brushed their teeth at pre-determined time periods. The amount of mercury vapor released per time unit was measured at intervals of 30-45 min by means of a measuring system based on atomic absorption spectrophotometry. None of the subjects was professionally exposed to mercury, and all of their amalgam fillings were more than one year old. Study casts were made for each subject, and the area of the amalgam surfaces was measured. Samples of urine and saliva were analyzed so that values for the mercury concentrations and the rate of release of mercury into saliva could be obtained. The average frequency of fish meals per month was noted.” (ABSTRACT TRUNCATED AT 250 WORDS)

“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.”

“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.”

“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.”

“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 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.”