Mercury

“84 patients with oral lichenoid lesions (OLL) were seen in the contact dermatitis clinic. All these patients had reticulate, lacy, plaque-like or erosive lichenoid changes adjacent to amalgam fillings. Patch testing to metallic mercury, 0.1% thimerosal, 1% ammoniated mercury, 0.1% mercuric chloride, and in some cases 0.05% phenylmercuric nitrate and amalgam discs was undertaken. 33 (39%) patients had positive patch test findings. 30/33 patch test positive patients had replacement of their amalgam fillings, with 28 (87%) patients experiencing improvement of symptoms and signs within 3 months. This confirms that mercury allergy is a factor in the pathogenesis of OLL in some cases. In cases where patch test negative patients improve with amalgam replacement, mercury may be acting as an irritant in the pathogenesis of OLL.”

“A 3 1/2-year-old boy presented on three occasions with painful, itchy, oedematous plaques on his limbs. On two occasions he had received hepatitis B vaccination 11-13 days previously, and on the third occasion received triple antigen (DTP) vaccination 10 days earlier. Skin biopsy revealed a prominent infiltrate of eosinophils involving the entire thickness of the dermis. In addition there were prominent ‘flame figures’ consisting of eosinophilic necrotic collagen surrounded by granular basophilic debris. The clinical and histological pictures were consistent with Wells’ syndrome. The eruption settled on the second and third occasions with 0.1% mometasone furoate cream. Subsequent patch testing showed 2+ reaction to preservative thiomersal at 96 hours. This is the first description of Wells’ syndrome with typical clinical and histopathological features associated with thiomersal in two different vaccines.”

“The effect of thimerosal, a reactive oxidant, on cytoplasmic free Ca2+ concentrations ([Ca2+]i) in Madin Darby canine kidney (MDCK) cells was explored by using the Ca2+-sensitive dye fura-2. Thimerosal acted in a concentration-dependent manner with an EC50 of 0.5 microM. The Ca2+ signal comprised a gradual rise and a sustained elevation. Removal of extracellular Ca2+ reduced 80% of the signal. In Ca2+-free medium, the [Ca2+]i rise induced by 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) was completely inhibited by pretreatment with 5 microM thimerosal. The thimerosal (5 microM)-induced Ca2+ release was not changed by inhibition of phospholipase C with 2 microM U73122. Collectively, this study shows that thimerosal induced [Ca2+]i rises in renal tubular cells via releasing store Ca2+ from the endoplasmic reticulum Ca2+ stores in a manner independent of phospholipase C activity.”

“Thiomersal (thimerosal) was a weak inhibitor of the binding of [(3)H]mepyramine to histamine H(1) receptors in guinea-pig cerebellar membranes (11 +/- 1% inhibition at 10 microM, 32 +/- 3% inhibition at 300 microM). However, in the concentration range 3-30 microM, thiomersal enhanced the binding of histamine to the H(1) receptor, as reflected by the displacement of curves of histamine inhibition of [(3)H]mepyramine binding to lower concentrations, without any change in the Hill coefficient. The ratio of the IC50 values (the concentration giving 50% inhibition) in the absence and presence of thiomersal increased from 1.8 with 3 microM to 3.6 with 30 microM thiomersal. There was no consistent effect of thiomersal at concentrations of 30 microM and below on curves of mepyramine inhibition of [(3)H]mepyramine binding. In the presence of 10 microM thiomersal histamine-induced accumulation of inositol phosphates in U373 MG astrocytoma cells was partially inhibited (37 +/- 8% inhibition of the maximum response), without any significant change in the EC50 (the concentration giving the half maximal response) for histamine. Thus although histamine binding was potentiated by thiomersal, there was no potentiation of an H(1) receptor-mediated functional response.”

“In their Perspective article, Bolger and Schwetz1 recommend limiting the intake of mercury by reducing the consumption of mercury-contaminated fish because of possible negative cardiovascular and neurologic effects. We were surprised that they do not mention dental amalgam. Dental amalgam consists of 50 percent elemental mercury, and it is well known that mercury vapor is released from amalgam.”

“The source document upon which this CICAD is based is the Toxicological profile for mercury (update), published by the Agency for Toxic Substances and Disease Registry of the US Department of Health and Human Services (ATSDR, 1999). Data identified as of January 1999 were considered in the source document. Data identified as of November 1999 were considered in the preparation of this CICAD. Information on the availability and the peer review of the source document is presented in Appendix 1. Information on the peer review of this CICAD is presented in Appendix 2. This CICAD was considered at a meeting of the Final Review Board, held in Helsinki, Finland, on 26–29 June 2000 and approved as an international assessment by mail ballot of the Final Review Board members on 27 September 2002. Participants at the Final Review Board meeting are presented in Appendix 3. The International Chemical Safety Cards for elemental mercury and six inorganic mercury compounds, produced by the International Programme on Chemical Safety, have also been reproduced in this document.”

“We were initially highly skeptical that differences in the concentrations of thimerosal in vaccines would have any effect on the incidence rate of neurodevelopmental disorders after childhood immunization. This study presents the first epidemiologic evidence, based upon tens of millions of doses of vaccine administered in the United States, that associates increasing thimerosal from vaccines with neurodevelopmental disorders. Specifically, an analysis of the Vaccine Adverse Events Reporting System (VAERS) database showed statistical increases in the incidence rate of autism (relative risk [RR] = 6.0), mental retardation (RR = 6.1), and speech disorders (RR = 2.2) after thimerosal-containing diphtheria, tetanus, and acellular pertussis (DTaP) vaccines in comparison with thimerosal-free DTaP vaccines. The male/female ratio indicated that autism (17) and speech disorders (2.3) were reported more in males than females after thimerosal-containing DTaP vaccines, whereas mental retardation (1.2) was more evenly reported among male and female vaccine recipients. Controls were employed to determine if biases were present in the data, but none were found. It was determined that overall adverse reactions were reported in similar-aged populations after thimerosal-containing DTaP (2.4 +/- 3.2 years old) and thimerosal-free DTaP (2.1 +/- 2.8 years old) vaccinations. Acute control adverse reactions such as deaths (RR = 1.0), vasculitis (RR = 1.2), seizures (RR = 1.6), ED visits (RR = 1.4), total adverse reactions (RR = 1.4), and gastroenteritis (RR = 1.1) were reported similarly after thimerosal-containing and thimerosal-free DTaP vaccines. An association between neurodevelopmental disorders and thimerosal-containing DTaP vaccines was found, but additional studies should be conducted to confirm and extend this study.”

“Dentists are exposed to mercury (Hg) during the removal of amalgam fillings. Recent research on dentists and other occupational groups report neurological impairment at Hg exposure levels below the current occupational TLV® (25 µg/m3) and/or the occupational BEI® (35 µg/ Hg/g creatinine in urine). Surveys of Hg° in the general office air of dental offices fail to measure the high levels of Hg-laden respirable amalgam particulate matter sprayed into the dentist’s breathing zone during the removal of old amalgam fillings. This respirable particulate matter represents the vast majority of daily Hg exposure in practicing dentists. Despite this, no research is available on the pharmacokinetic fate of inhaled particulate amalgam Hg in humans. What indirect data does exist demonstrates that absorption from the lung occurs but that fecal excretion may predominate. As a result, urine analysis for Hg may be ineffective as a means of occupational monitoring. Various countries are moving to limit the use of amalgam as a dental restorative material in order to protect dental patients from Hg exposure. However, dentists’ occupational exposure should also be considered as a justification for reduced amalgam use.”

“Mercury is a heavy metal widely used by man. It is considered very toxic causing conditions in the central nervous system, behavior disturbances, and renal and sexual disorders. For a century, mercury has been used in the dental practice for its capacity of joining metals (amalgamate), its low cost and its rapid fixing in dental pieces repair. Currently, there is much controversy about the safety of dental amalgams and it has been demonstrated it poses occupational risks to dental practitioners and their assistants. The objective of this study is review aspects related to metallic mercury toxicity for personnel involved in the dental practice and patients with dental amalgams. Routes of mercury exposure in dentistry, occupational risks and measures to prevent mercury poisoning are presented here. A literature review was conducted mostly on data from Biological Abstracts and the Science Citation Index for the period between 1990 and 2000.”

“Large autism epidemics have recently been reported in the United States and the United Kingdom. Emerging epidemiologic evidence and biologic plausibility suggest an association between autistic spectrum disorders and mercury exposure. This study compares mercury excretion after a three-day treatment with an oral chelating agent, meso-2,3- dimercaptosuccinic acid (DMSA), in children with autistic spectrum disorders and a matched control population. Overall, urinary mercury concentrations were significantly higher in 221 children with autistic spectrum disorders than in 18 normal controls (Relative Increase (RI)=3.15; P < 0.0002). Additionally, vaccinated cases showed a significantly higher urinary mercury concentration than did vaccinated controls (RI=5.94; P < 0.005). Similar urinary mercury concentrations were observed among matched vaccinated and unvaccinated controls, and no association was found between urinary cadmium or lead concentrations and autistic spectrum disorders. The observed urinary concentrations of mercury could plausibly have resulted from thimerosal in childhood vaccines, although other environmental sources and thimerosal in Rh (D) immune globulin administered to mothers may be contributory. Regardless of the mechanism by which children with autistic spectrum disorders have high urinary mercury concentrations, the DMSA treatment described in this study might be useful to diagnose their present burden of mercury.”