Mercury

“In dentistry, there is a lot of controversy about the topic of silver mercury fillings; are they safe or not safe? There are many articles written on the pros and cons of these types of fillings. It is difficult to quantify and to assess the effects in each individual. It is not easy to identify silver mercury fillings as the cause if illness presents or if the fillings contributed to illness, except in extreme toxicity cases. Refer to the beginning sections of this review paper concerning the science and mechanism of how mercury interconnects with body tissues and functions.
Environmental doctors investigate heavy metal toxicity as part of their overall wellness regiment to help their patients with health concerns. These doctors look at sources of metals when the patient’s lab reports/diagnostic tests show high levels of mercury and other metals. They investigate what sources are contributing and how to reduce the burden on the body. The doctor may prescribe the safe removal of silver mercury fillings so as not to create an additional burden on the body and to help their patient heal. Thus, when removing amalgams, additional steps help ensure that the patient is protected.”

“New filling materials were introduced in Norway in the 1970s, and were gradually preferred for aesthetic reasons. Focus on dental amalgam as an environmental problem emerged during the 1980s as part of a broader policy to limit emissions of mercury. In 1991 the health authorities issued guidelines recommending dentists to reduce the use of dental amalgam, and new guidelines from 2003 required that other materials than dental amalgam should be considered as the first choice in tooth fillings. Preventive use of fluoride has also contributed to improved dental health and reduced use of dental amalgam.
A requirement to have an approved dental amalgam separator installed in all dental clinics was introduced in 1994. Requirements to control the mercury air emissions from crematoria with more than 200 cremations per year were implemented in 2007.
Norway introduced a general ban on the use of mercury in products from 2008. Limited exemptions for dental amalgam use were applied until the end of 2010.”

“Dental amalgam is a metallic restorative material that is used for direct filling of carious lesions since many years. The use of this material generates solid and particulate wastes that present potential challenges to the environment. This study was carried out to assess amalgam use and waste management protocols practiced by Moroccan and Burkinabe dentists. A cross-sectional study was made of 79 in Rabat, Sale and Temara in Morocco and 56 in Ouagadougou, Bobo-Dioulasso in Burkina-Faso. The results showed that 69.5% of dental amalgam waste in Morocco vs 49.9% in Burkina-Faso was disposed with household waste which is a problem for both the environment and a risk to human being. Proper methods of dental amalgam waste disposal should be carried out to prevent indirect mercury poisoning for human.”

“The aim of this study was to investigate total mercury (THg) and methylmercury (MeHg) exposure of 75 mother-child pairs in relation to their thyroid hormone status (thyroid-stimulating hormone (TSH), triiodothyronine (T3), free triiodothyronine (fT3), thyroxine (T4), and free thyroxine (fT4)). THg and MeHg in blood samples were measured by atomic absorption spectrometry and gas chromatography-inductively coupled plasma-mass spectrometry, respectively. The median THg and MeHg levels in maternal blood, cord blood, and blood of 6-month-old children were 0.50, 0.53, and 0.32 and 0.22, 0.32, and 0.08 µg/L, respectively. There were significant correlations between paired maternal-cord blood levels for THg and MeHg, with a greater transplacental transport of MeHg compared with THg (mean cord/maternal blood ratio, 1.80 vs. 1.24). The maternal blood THg was found to be a better predictor of TSH levels in children than their current THg exposure. There was a positive correlation between maternal THg and children’s TSH. T3 and fT3 levels in children were negatively related to cord blood THg in the majority (Caucasian) subgroup, whereas these associations were positive in the Roma subgroup. Mothers with dental amalgam fillings had significantly lower T4 and fT4 levels. Moreover, fT4 in the mothers of boys negatively correlated with maternal THg levels. MeHg exposure lowered T3 levels in the mothers of girls. Our results suggest that low-level exposure to Hg can affect thyroid hormone status during prenatal and early postnatal exposure depending on the form of Hg, gender, ethnicity, lifestyle, or socioeconomic status (dental amalgam fillings).”

Increasing emissions of anthropogenic mercury represents a growing concern to the health of high trophic level marine mammals. In its organic form, this metal bioaccumulates, and can be toxic to several physiological endpoints, including the immune system. In this study, we (1) evaluated the effects of inorganic mercury (mercuric chloride, HgCl2) and organic mercury (methylmercuric chloride, MeHgCl) on the in vitro function of lymphocytes isolated from the peripheral blood of beluga whales (Delphinapterus leucas); (2) characterized the potential protective effects of sodium selenite (Na2SeO3) on cell proliferation of HgCl2 or MeHgCl-treated beluga whale lymphocytes; and (3) compared these dose-dependent effects to measurements of blood Hg in samples collected from traditionally harvested beluga whales in the western Canadian Arctic. Lymphocyte proliferative responses were reduced following exposure to 1 μM of HgCl2 and 0.33 μM of MeHgCl. Decreased intracellular thiol levels were observed at 10 μM of HgCl2 and 0.33 μM of MeHgCl. Metallothionein induction was noted at 0.33 μM of MeHgCl. Concurrent exposure of Se provided a degree of protection against the highest concentrations of inorganic Hg (3.33 and 10 μM) or organic Hg (10 μM) for T-lymphocytes. This in vitro protection of Se against Hg toxicity to lymphocytes may contribute to the in vivo protection in beluga whales exposed to high Hg concentrations. Current Hg levels in free-ranging beluga whales from the Arctic fall into the range of exposures which elicited effects on lymphocytes in our study, highlighting the potential for effects on host resistance to disease. The implications of a changing Arctic climate on Hg fate in beluga food webs and the consequences for the health of beluga whales remain pressing research need

“Human oral mucosa is subjected to many noxious stimuli. One of these substances, in those who have restorations, is dental amalgam which contains mercury. This paper focuses on the local toxic effects of amalgam and mercury from dental restorations. Components of amalgam may, in rare instances, cause local side effects or allergic reactions referred to as oral lichenoid lesions (OLLs). OLLs to amalgams are recognised as hypersensitivity reactions to low-level mercury exposure. The use of patch testing to identify those susceptible from OLL is explored, and recommendations for removing amalgam fillings, when indicated are outlined. We conclude that evidence does not show that exposure to mercury from amalgam restorations poses a serious health risk in humans, except for an exceedingly small number of hypersensitivity reactions that are discussed.”

“Thimerosal, a mercury-containing vaccine preservative, is a suspected factor in the etiology of neurodevelopmental disorders. We previously showed that its administration to infant rats causes behavioral, neurochemical and neuropathological abnormalities similar to those present in autism. Here we examined, using microdialysis, the effect of thimerosal on extracellular levels of neuroactive amino acids in the rat prefrontal cortex (PFC). Thimerosal administration (4 injections, i.m., 240 ?g Hg/kg on postnatal days 7, 9, 11, 15) induced lasting changes in amino acid overflow: an increase of glutamate and aspartate accompanied by a decrease of glycine and alanine; measured 10-14 weeks after the injections. Four injections of thimerosal at a dose of 12.5 ?g Hg/kg did not alter glutamate and aspartate concentrations at microdialysis time (but based on thimerosal pharmacokinetics, could have been effective soon after its injection). Application of thimerosal to the PFC in perfusion fluid evoked a rapid increase of glutamate overflow. Coadministration of the neurosteroid, dehydroepiandrosterone sulfate (DHEAS; 80 mg/kg; i.p.) prevented the thimerosal effect on glutamate and aspartate; the steroid alone had no influence on these amino acids. Coapplication of DHEAS with thimerosal in perfusion fluid also blocked the acute action of thimerosal on glutamate. In contrast, DHEAS alone reduced overflow of glycine and alanine, somewhat potentiating the thimerosal effect on these amino acids. Since excessive accumulation of extracellular glutamate is linked with excitotoxicity, our data imply that neonatal exposure to thimerosal-containing vaccines might induce excitotoxic brain injuries, leading to neurodevelopmental disorders. DHEAS may partially protect against mercurials-induced neurotoxicity.”

“Neurodevelopment as Gesell development scores (GDSs) in relation to mercury exposure in infants (<6 months of age) of one urban center and two rural villages, respectively, of fisherman and cassiterite miners. Mean total hair-Hg (HHg) concentrations of infants from Itapuã (3.95 ± 1.8?ppm) were statistically (P = 0.0001) different from those of infants from Porto Velho (3.84 ± 5.5?ppm) and Bom Futuro (1.85 ± 0.9?ppm). Differences in vaccine coverage among these populations resulted in significantly higher (P = 0.0001) mean ethylmercury (EtHg) exposure in urban infants (150??g) than in infants from either village (41.67??g, Itapuã; 42.39??g, Bom Futuro). There was an inverse significant (Spearman r = -0.2300; P = 0.0376) correlation between HHg and GDS for infants from Porto Velho, but not for the rural infants from Bom Futuro (Spearman r = 0.1336; P = 0.0862) and Itapuã (Spearman r = 0.1666; P = 0.5182). Logistic regression applied to variables above or below the median GDS showed that EtHg exposure (estimated probability = -0.0157; P = 0.0070) and breastfeeding score (estimated probability = -0.0066; P = 0.0536) score were significantly associated with GDS. Conclusion. In nurslings whose mothers are exposed to different levels of fish-MeHg (HHg), a higher score of neurological development at six months was negatively associated with exposure to additional TCV-EtHg. Results should be interpreted with caution because of unaccounted variables.”

“Monitoring T cells in combination with humoral response may be of value to predict clinical protection and cross-protective immunity after influenza vaccination. Elispot technique which measures cytokine produced after antigen-specific T cell stimulation is used routinely to detect and characterize anti-viral T cells. We found that the preservative thimerosal present in most H1N1 pandemic vaccines, induced in vitro abortive activation of T cells followed by cell death leading to false-positive results with the Elispot technique. The size of the spots, usually not measured in routine analysis, appears to be a discriminative criterion to detect this bias. Multi-dose vials of vaccine containing thimerosal remain important for vaccine delivery and our results alert about false-positive results of Elispot to monitor the clinical efficacy of these vaccines. We showed that this finding extends for other T cell monitoring techniques based on cytokine production such as ELISA. Although measuring in vitro immune response using the whole vaccine used for human immunization directly reflects in vivo global host response to the vaccine, the present study strongly supports the use of individual vaccine components for immune monitoring due to the presence of contaminants, such as thimerosal, leading to a bias in interpretation of the results.”

“Prenatal mercury exposure and its fetotoxic effects may be of particular concern in urban immigrant communities as a result of possible contributing cultural factors. The most common source of exposure in these communities is ingestion of fish and shellfish contaminated with methylmercury. Other sources of exposure may occur in ritualistic practices associated with Hispanic and Caribbean-based religions. This study 1) assessed total mercury levels in both random urine specimens from pregnant women, and in cord blood; and 2) examined environmental sources of exposure from a convenience sample in a predominantly Caribbean immigrant population in Brooklyn, New York. A questionnaire designed in collaboration with health professionals from the Caribbean community assessed the frequency of fish consumption, ritualistic practices, occupational exposures, and use of dental amalgams and mercury-containing skin and household products. The geometric mean for total mercury in cord blood was 2.14 µg L(-1) (95%CI: 1.76-2.60) (n = 78), and 0.45 µg L(-1) (95%CI: 0.37-0.55) (n = 183) in maternal urine corrected for creatinine (µg g(-1)). Sixteen percent of cord blood mercury levels exceeded the estimated equivalent of U.S. Environmental Protection Agency’s Reference Dose (5.8 µg L(-1) blood). Predictors of cord blood mercury included maternal fish consumption and foreign birth of the mother. Predictors of urine mercury included foreign birth of the mother, number of dental amalgams, and special product use. There were no reports of mercury use in ritualistic practices or in cosmetics; however some women reported use of religious medals and charms. This study characterized risk factors for mercury exposure in a sample of urban, predominantly Caribbean-born blacks. Findings may help target interventions in this population, which might include appropriate fish selection and consumption frequency during pregnancy, and safe handling of mercury-containing products in the home.”