Mercury

“Mercury (Hg) exposure in human infants and fetuses has long been known to be significantly
associated with neurodevelopmental disorders (NDs). Thimerosal (49.55% Hg by weight) is an ethyl-Hg
containing compound added to many childhood vaccines as a preservative. A hypothesis testing case-control
study was undertaken in the Vaccine Adverse Event Reporting System (VAERS) database (updated through
September 2013) by examining 5,591 adverse event reports entered following Thimerosal-preserved
Diphtheria-Tetanus-acellular-Pertussis (DTaP) (TripediaTM, Sanofi) administered from 1997-1999 (exposed)
and following Thimerosal-reduced DTaP (TripediaTM, Sanofi) administered from 2004-2006 (unexposed).
Cases were defined as individuals with adverse event reports with the outcomes of autism, speech disorder,
mental retardation, or ND (at least of one these aforementioned specific outcomes being mentioned in the
adverse event report). Controls were defined as individuals with adverse event reports without any mention of
the specific case outcomes examined. Cases reported with the outcomes of autism (odds ratio = 7.67, p <
0.0001), speech disorders (odds ratio = 3.49, p < 0.02), mental retardation (odds ratio = 8.73, p < 0.0005), or
ND (odds ratio = 4.82, p < 0.0001) were significantly more likely than controls to have received Thimerosalpreserved
DTaP vaccine (exposed) in comparison to Thimerosal-reduced DTaP vaccine (unexposed). Though
routine childhood vaccination is considered an important public health tool to reduce the morbidity and
mortality associated with certain infectious diseases, this study supports a significant relationship between
increased organic-Hg exposure from Thimerosal-preserved childhood vaccines and the child’s subsequent risk
of a ND diagnosis. “

“BACKGROUND:
Within the first 3 years of life, the brain develops rapidly. Its development is characterized by critical developmental periods for speech, vision, hearing, language, balance, etc.; and alteration in any of the processes occurring in those critical periods can lead to specific delays in development.

AIMS:
The present study evaluated the potential toxic effects of organic-mercury exposure from Thimerosal (49.55% mercury by weight) in childhood vaccines and its hypothesized possible relationship with specific delays in development.

MATERIALS AND METHODS:
A hypothesis testing case-control study was undertaken to evaluate the relationship between exposure to Thimerosal-containing hepatitis B vaccines administered at specific intervals in the first 6 months among cases diagnosed with specific delays in development and controls born between 1991-2000, utilizing data in the Vaccine Safety Datalink database.

RESULTS:
Cases were significantly more likely than controls to have received increased organic-mercury from Thimerosal-containing hepatitis B vaccine administered in the first, second, and sixth month of life.

CONCLUSION:
Though routine childhood vaccination may be an important public health tool to reduce the morbidity and mortality associated with infectious diseases, the present study supports an association between increasing organic-mercury exposure from Thimerosal-containing childhood vaccines and the subsequent risk of specific delays in development among males and females.”

“A hypothesis testing case-control study evaluated concerns about the toxic effects of organic-mercury (Hg) exposure from thimerosal-containing (49.55% Hg by weight) vaccines on the risk of neurodevelopmental disorders (NDs). Automated medical records were examined to identify cases and controls enrolled from their date-of-birth (1991-2000) in the Vaccine Safety Datalink (VSD) project. ND cases were diagnosed with pervasive developmental disorder (PDD), specific developmental delay, tic disorder or hyperkinetic syndrome of childhood. In addition, putative non-thimerosal-related outcomes of febrile seizure, failure to thrive and cerebral degenerations were examined. The cumulative total dose of Hg exposure from thimerosal-containing hepatitis B vaccine (T-HBV) administered within the first six months of life was calculated. On a per microgram of organic-Hg basis, PDD (odds ratio (OR) = 1.054), specific developmental delay (OR = 1.035), tic disorder (OR = 1.034) and hyperkinetic syndrome of childhood (OR = 1.05) cases were significantly more likely than controls to receive increased organic-Hg exposure. By contrast, none of the non-thimerosal related outcomes were significantly more likely than the controls to have received increased organic-Hg exposure. Routine childhood vaccination may be an important public health tool to reduce infectious disease-associated morbidity/mortality, but the present study significantly associates organic-Hg exposure from T-HBV with an increased risk of an ND diagnosis.”

“Mercury (Hg) is neurotoxic and children may be particularly susceptible to this effect. A current major challenge is identification of children who may be uniquely susceptible to Hg toxicity because of genetic disposition. This study examined the hypothesis that genetic variants of catechol-O-methyltransferase (COMT) that are reported to alter neurobehavioral functions that are also affected by Hg in adults might modify the adverse neurobehavioral effects of Hg exposure in children. Five hundred and seven children, 8–12 yr of age at baseline, participated in a clinical trial to evaluate the neurobehavioral effects of Hg from dental amalgam tooth fillings. Subjects were evaluated at baseline and at seven subsequent annual intervals for neurobehavioral performance and urinary Hg levels. Following the clinical trial, genotyping assays were performed for single-nucleotide polymorphisms (SNPs) of COMT rs4680, rs4633, rs4818, and rs6269 on biological samples provided by 330 of the trial participants. Regression-modeling strategies were employed to evaluate associations between allelic status, Hg exposure, and neurobehavioral test outcomes. Similar analysis was performed using haplotypes of COMT SNPs. Among girls, few interactions for Hg exposure and COMT variants were found. In contrast, among boys, numerous gene–Hg interactions were observed between individual COMT SNPs, as well as with a common COMT haplotype affecting multiple domains of neurobehavioral function. These findings suggest increased susceptibility to the adverse neurobehavioral effects of Hg among children with common genetic variants of COMT, and may have important implications for strategies aimed at protecting children from the potential health risks associated with Hg exposure.”

Mercury is among the most toxic heavy metals and has no known physiological role in humans. Three forms of mercury exist: elemental, inorganic and organic. Mercury has been used by man since ancient times. Among the earliest were the Chinese and Romans, who employed cinnabar (mercury sulfide) as a red dye in ink (Clarkson et al. 2007). Mercury has also been used to purify gold and silver minerals by forming amalgams. This is a hazardous practice, but is still widespread in Brazil’s Amazon basin, in Laos and in Venezuela, where tens of thousands of miners are engaged in local mining activities to find and purify gold or silver. Mercury compounds were long used to treat syphilis and the element is still used as an antiseptic,as a medicinal preservative and as a fungicide. Dental amalgams, which contain about 50% mercury, have been used to repair dental caries in the U.S. since 1856.Mercury still exists in many common household products around the world.Examples are: thermometers, barometers, batteries, and light bulbs (Swain et al.2007). In small amounts, some organo mercury-compounds (e.g., ethylmercury tiosalicylate(thimerosal) and phenylmercury nitrate) are used as preservatives in some medicines and vaccines (Ballet al. 2001).Each mercury form has its own toxicity profile. Exposure to Hg0 vapor and MeHg produce symptoms in CNS, whereas, the kidney is the target organ when exposures to the mono- and di-valent salts of mercury (Hg+ and Hg++, respectively)occur. Chronic exposure to inorganic mercury produces stomatitis, erethism and tremors. Chronic MeHg exposure induced symptoms similar to those observed in ALS, such as the early onset of hind limb weakness (Johnson and Atchison 2009).Among the organic mercury compounds, MeHg is the most biologically available and toxic (Scheuhammer et a!. 2007). MeHg is neurotoxic, reaching high levels of accumulation in the CNS; it can impair physiological function by disrupting endocrine glands (Tan et a!. 2009).The most important mechanism by which mercury causes toxicity appears to bemitochondrial damage via depletion of GSH (Nicole et a!. 1998), coupled with binding to thiol groups ( -SH), which generates free radicals. Mercury has a high affinity for thiol groups ( -SH) and seleno groups ( -SeH) that are present in amino acids as cysteine and N-acetyl cysteine, lipoic acid, proteins, and enzymes. N-acetylcysteine and cysteine are precursors for the biosynthesis of GSH, which is among the most powerful intracellular antioxidants available to protect against oxidative stress and inflammation.Mercury and methylmercury induce mitochondrial dysfunction, which reduces ATP synthesis and increases lipid, protein and DNA peroxidation. The content of metallothioneines, GSH, selenium and fish high in omega-3 fatty acids appear to be strongly related with degree of inorganic and organic mercury toxicity, and with the protective detoxifying mechanisms in humans. In conclusion, depletion of GSH,breakage of mitochondria, increased lipid peroxidation, and oxidation of proteins and DNA in the brain, induced by mercury and his salts, appear to be important factors in conditions such as ALS and AD (Bains and Shaw 1997; Nicole eta!. 1998;Spencer eta!. 1998; Alberti et a!. 1999).

“Mercury (Hg) exposure in human infants and fetuses has long been known to be significantly associated with neurodevelopmental disorders (NDs). Thimerosal (49.55% Hg by weight) is an ethyl-Hg containing compound added to many childhood vaccines as a preservative. A hypothesis testing case-control study was undertaken in the Vaccine Adverse Event Reporting System (VAERS) database (updated through September 2013) by examining 5,591 adverse event reports entered following Thimerosal-preserved Diphtheria-Tetanus-acellular-Pertussis (DTaP) (TripediaTM, Sanofi) administered from 1997-1999 (exposed) and following Thimerosal-reduced DTaP (TripediaTM, Sanofi) administered from 2004-2006 (unexposed). Cases were defined as individuals with adverse event reports with the outcomes of autism, speech disorder, mental retardation, or ND (at least of one these aforementioned specific outcomes being mentioned in the adverse event report). Controls were defined as individuals with adverse event reports without any mention of the specific case outcomes examined. Cases reported with the outcomes of autism (odds ratio = 7.67, p < 0.0001), speech disorders (odds ratio = 3.49, p < 0.02), mental retardation (odds ratio = 8.73, p < 0.0005), or ND (odds ratio = 4.82, p < 0.0001) were significantly more likely than controls to have received Thimerosal preserved DTaP vaccine (exposed) in comparison to Thimerosal-reduced DTaP vaccine (unexposed). Though routine childhood vaccination is considered an important public health tool to reduce the morbidity and mortality associated with certain infectious diseases, this study supports a significant relationship between increased organic-Hg exposure from Thimerosal-preserved childhood vaccines and the child’s subsequent risk of a ND diagnosis. “

“The restorative materials we use today have all been developed with ‘most people’ in mind. Most people can put up with a bit of toxicity, immune reactivity and galvanic stress. However, there are outliers, and perhaps their numbers are growing, who can’t stand up to those stresses as well as others. The prevalence of multiple chemical sensitivities (MCS) has been reported to be somewhere between 12 and 33% in the general population, with 2 to 6% having been actually diagnosed as such.”

“Neurological outcomes (Gesell development schedules [GDS]), age of walking, and age of talking were studied in 299 toddlers (12 to 24 mo) in relation to environmental (fish consumption and tin mining) exposure. Exposure to fish methylmercury (MeHg) consumption and iatrogenic ethylmercury (EtHg) in Thimerosal-containing vaccines (TCV) was quantified in toddlers from two rural villages (n = 91, Itapuã; n = 218, Bom Futuro) respectively populated by fishers and cassiterite miners. Median total hair Hg (HHg) concentrations of infants from Itapuã (3.5 μg/g) were significantly higher than those of infants from Bom Futuro (2.2 μg/g). Median EtHg exposure from TCV was also significantly higher in toddlers from Itapuã (137.5 μg) than in those from Bom Futuro (112.5 μg). There were no significant differences between groups for any of the Gesell schedules; however, there were proportionally more compromised toddlers (GDS < 70) in Itapuã than Bom Futuro. Median age of talking was not statistically different but median age of walking was significantly higher in Bom Futuro. In toddlers from both villages, of fishers and miners, HHg concentrations were significantly correlated with family fish consumption. A logistic regression model was applied to all infants after classification into two groups: above or below the median Gesell schedules. Overall, there was no distinctive pattern of neurodevelopment associated with either HHg or EtHg exposure; however, nutritional status was significantly associated with GDS. In conclusion, milestone achievement was delayed in toddlers from tin-ore mining communities. Despite significantly higher exposure to both forms of organic Hg (MeHg from maternal fish consumption, and EtHg from TCV) in toddlers from the fishing village, significant differences were seen only among the proportions of most severely affected toddlers (GDS < 70).”

DESIGN:
In group A (20 patients), the oral lesions were confined to areas in close contact with amalgam fillings. In group B (20 patients), the lesions extended 1 cm beyond the area of contact with amalgam fillings. In group C (20 patients), the oral lesions had no topographic relationship with amalgam fillings. Partial or complete replacement of amalgam fillings was recommended if there was a positive patch test reaction to ammoniated mercury, metallic mercury, or amalgam. Control group D (20 patients) had signs of allergic contact dermatitis.

RESULTS:
Amalgam fillings were replaced in 13 patients of group A, with significant improvement. Dental amalgam was replaced in 8 patients of group B, with significant improvement. In group C, amalgam replacement in 2 patients resulted in improvement in 1 patient. These results were evaluated after 3 months. No positive patch test reactions to mercury compounds were found in patients with concomitant cutaneous lichen planus and in group D.

CONCLUSIONS:
Contact allergy to mercury compounds is important in the pathogenesis of oral lichen planus, especially if there is close contact with amalgam fillings and if no concomitant cutaneous lichen planus is present. In cases of positive patch test reactions to mercury compounds, partial or complete replacement of amalgam fillings will lead to a significant improvement in nearly all patients.

“There have been many developments in operative dentistry in recent years, including a progressive shift to the use of resin composites, rather than dental amalgam, in the restoration of posterior teeth. This shift allows the adoption of minimal intervention approaches, thereby helping to conserve and preserve remaining tooth tissues and structures. This paper presents the position of the Academy of Operative Dentistry European Section (AODES) in relation to posterior resin composites. The AODES considers adhesively bonded resin composites of suitable composition and properties to be the “material of choice” for use in direct minimal intervention approaches to the restoration of posterior teeth. In so doing, the AODES emphasises the importance of the practice of evidence–based, minimal intervention dentistry, including the use of refurbishment and repair techniques to extend the longevity of restorations. Guidance, based on best available evidence, has been made in relation to certain aspects of resin composite placement techniques in posterior teeth.”