Mercury

To clarify the situation of trans-placental movement and milk screening of metallic mercury in human, the content of mercury was detected in the maternal blood, umbilical cord blood, milk, and placental tissues. In 18 parturient women, 9 had been occupationally exposed to metallic mercury whereas the other 9 had not. Mercury was detected by means of cold vapor atomic absorption spectrophotometry. Results showed that the concentrations of mercury of the umbilical cord blood and placental tissues were higher than that of maternal blood. The ratio of organic and total mercury of milk was markedly lower than that of maternal blood in the exposed group (P < 0.01). The ratio of inorganic to total mercury of milk was significantly higher than that of maternal blood (P < 0.01). Therefore, this study concluded that the metallic mercury can be transferred to the fetus via the placenta and secreted to a newborn via milk.

“This paper reviews the basic methodology of risk assessment and describes the four steps involved, namely hazard identification, hazard evaluation, exposure evaluation, and risk estimation. The risk posed by the release of mercury vapor from dental amalgam restorations is used as an example to demonstrate the advantages and limitations of this process.”

“To estimate environmental burden of mercury from dental clinics, a survey was conducted in 1993 at dental clinics in northern part of Sweden. Factors regarding amalgam separators, maintenance and disposal of collected sludge, age of clinics, cleaning of waste pipes, and sorting and handling of amalgam contaminated products were investigated. The result showed that many were not familiar with maintenance of the amalgam separator. A majority, 68%, were working in clinics older than 10 years, but only 9% reported that waste pipes had been cleaned or changed. Classification of amalgam contaminated products as high-risk and low-risk waste differed a lot, as well as handling of waste products. The result shows that there is need for more information and attention to all individuals working in Dental Care on how to reduce environmental burden of mercury from dental clinics.”

“53 patients with complaints which they attributed to their amalgam fillings, and with pathological tests indicating abnormality of the immune system, were followed for 1-3 years after the removal of all, part of, or none of their amalgam fillings. Within the group of 34 individuals who had all their amalgam fillings replaced, there was a significant number of decreased antibody titres, but only two had normalised their laboratory tests after 1-3 years. A significant improvement in subjective symptoms occurred in 20 (59%) of cases. In the group of patients who still had amalgam fillings, there were no statistically significant changes in the antibody titres. It thus seems that mercury released from amalgam fillings may initiate or support an ongoing immune disease. However, this study group was rather heterogeneous and had received various pharmacological treatments. Further studies, are, therefore, needed to confirm, or refute, the results.”

“We report the presence of methyl mercury from the analysis of three samples of restorations associated with dental amalgam. We believe this to be the first finding of methyl mercury in the human mouth. Although the amounts found are small (4.0, 5.3 and 37.3 ng per sample), any measurable amount of methyl mercury contributes to the total body’s burden of mercury. Despite the long history of apparent safe use of dental amalgams, this finding obviously warrants further investigation and confirmation. A possible mechanism to explain the formation and distribution of methyl mercury from dental amalgams is proposed.”

“Mercury has been widely discussed in the pathogenesis of amyotrophic lateral sclerosis. [1,2] We describe a case of amyotrophic lateral sclerosis after accidental injection of mercury.”

“Clinical procedures in dental offices generate quantities of waste slurry or fine particulate matter, much of which is derived from dental amalgam filling material. This mercury-containing material is discharged into waste streams via the dental office vacuum-pump system. This system also discharges large quantities of air, either into the atmosphere exterior to the office building or into the sewer system, depending on the type of equipment used. The purpose of this study was to investigate whether the discharged air contained mercury vapor.”

“Modulation of the agonist-specific cytosolic Ca2+ oscillatory pattern by thimerosal has been investigated in single pancreatic acinar cells using patch-clamp perforated whole-cell recording to measure the calcium-dependent chloride current (I(C1)(Ca2+)). 1 microM thimerosal, which fails to evoke Ca2+ oscillation alone, clearly changed the pattern of Ca2+ oscillation from pulsatile spikes (evoked by low concentrations of activators) to sinusoidal or transient oscillations. The mimetic action of thimerosal was independent of extracellular Ca2+, was blocked by extracellular application of dithiothreitol or 10 mM caffeine, as well as by internal perfusion with heparin; but was unaffected by ruthenium red. We conclude that thimerosal modulates the agonist-specific cytosolic Ca2+ oscillatory patterns mediated by sensitizing the InsP3-induced Ca2+ release.”

“In experimental studies, chewing gum has been shown to increase the release rate of mercury vapor from dental amalgam fillings. The aim of the present study was to investigate the influence of long-term frequent chewing on mercury levels in plasma and urine. Mercury levels in plasma (P-Hg) and urine (U-Hg), and urinary cotinine were examined in 18 subjects who regularly used nicotine chewing gum, and in 19 referents. Age and number of amalgam surfaces were similar in the two groups. Total mercury concentrations in plasma and urine were determined by means of cold vapor atomic absorption spectrometry. Urinary cotinine was determined by gas chromatography-mass spectrometry. The chewers had been using 10 (median) pieces of gum per day for the past 27 (median) months. P-Hg and U-Hg levels were significantly higher in the chewers (27 nmol/L and 6.5 nmol/mmol creatinine) than in the referents (4.9 nmol/L and 1.2 nmol/mmol creatinine). In both groups, significant correlations were found between P-Hg or U-Hg on the one hand and the number of amalgam surfaces on the other. In the chewers, no correlations were found between P-Hg or U-Hg and chewing time per day or cotinine in urine. Cotinine in urine increased with the number of pieces of chewing gum used. The impact of excessive chewing on mercury levels was considerable.”

“The effects of 2,5-di-tert-butylhydroquinone (DBHQ) and thimerosal on phosphatidylserine synthesis by the base exchange reaction and on calcium mobilization in intact glioma C6 cells were compared with that of thapsigargin, a selective inhibitor of the endoplasmic reticulum Ca(2+)-ATPase. It has been found that all these agents inhibit phosphatidylserine synthesis by 70%, but their effectiveness are different. The data show that this inhibition is caused by Ca2+ depletion of the endoplasmic reticulum, indicating that phosphatidylserine synthesis requires high concentration of Ca2+ within this structure. On this basis and on literature data, a new model for the localization of the serine base exchange enzyme in the endoplasmic reticulum membrane is proposed.”