Mercury

“Thimerosal is an organic mercury compound that is used as a preservative in vaccines and pharmaceutical products. Recent studies have shown a TH2-skewing effect of mercury, although the underlying mechanisms have not been identified. In this study, we investigated whether thimerosal can exercise a TH2-promoting effect through modulation of functions of dendritic cells (DC). Thimerosal, in a concentration-dependent manner, inhibited the secretion of LPS-induced proinflammatory cytokines TNF-alpha, IL-6, and IL-12p70 from human monocyte-derived DC. However, the secretion of IL-10 from DC was not affected. These thimerosal-exposed DC induced increased TH2 (IL-5 and IL-13) and decreased TH1 (IFN-gamma) cytokine secretion from the T cells in the absence of additional thimerosal added to the coculture. Thimerosal exposure of DC led to the depletion of intracellular glutathione (GSH), and addition of exogenous GSH to DC abolished the TH2-promoting effect of thimerosal-treated DC, restoring secretion of TNF-alpha, IL-6, and IL-12p70 by DC and IFN-gamma secretion by T cells. These data suggest that modulation of TH2 responses by mercury and thimerosal, in particular, is through depletion of GSH in DC.”

“BACKGROUND:

The New England Children’s Amalgam Trial (NECAT) was a five-year randomized trial of 534 6- to 10-year-old children that compared the neuropsychological outcomes of those whose caries were restored using dental amalgam with the outcomes of those those whose caries were restored using mercury-free resin-based composite. The primary intention-to-treat analyses did not reveal significant differences between the treatment groups on the primary or secondary outcomes of the administered psychological tests: Full-Scale IQ score on the Wechsler Intelligence Scale for Children-Third Edition, General Memory Index of the Wide Range Assessment of Memory and Learning, and Visual-Motor Composite of the Wide Range Assessment of Visual Motor Abilities.

METHODS:

To determine whether treatment group assignment, a dichotomous measure of exposure, was sufficiently sensitive to detect associations between mercury exposure and these outcomes, the authors conducted analyses to evaluate the associations between the primary and secondary outcomes and two continuously distributed indexes of potential exposure, surface-years of amalgam and urinary mercury excretion.

RESULTS:

Neither index of mercury exposure was significantly associated with any of the three outcomes.

CONCLUSIONS:

The authors found no evidence that exposure to mercury from dental amalgam was associated with any adverse neuropsychological effects over the five-year period after placement of amalgam restorations.

CLINICAL IMPLICATIONS:

Analyses of the outcomes of the NECAT study indicate that use of dental amalgam was not associated with an increase in children’s risk of experiencing neuropsychological dysfunction.”

“Dentists all over the world remove millions of amalgam fillings every day, with no regard for the possible mercury exposure that can result from grinding them out. Much of the time, a new amalgam filling goes back in place of the old one. The dental establishment claims that amalgam is a stable material, that emits little or no mercury, but then turns around and blames the mercury–free dentists for “unnecessarily exposing patients to excess mercury” when removing amalgams electively. Well, which is it? Stable, or mercury emitting?”

“Mercury comes in different forms, most of which are toxic to humans, ecosystems and wild-life. High doses can be fatal to humans, but even relatively low doses of mercury containing compounds can have serious adverse neurodevelopmental impacts, and have recently been linked to possible harmful effects on the cardiovascular, immune and reproductive systems.”

“BACKGROUND:

The US is in the midst of an epidemic of neurodevelopmental disorders (NDs). Thimerosal is an ethylmercury-containing compound added to some childhood vaccines. Several previous epidemiological studies conducted in the US have associated Thimerosal-containing vaccine (TCV) administration with NDs.

MATERIAL/METHODS:

An ecological study was undertaken to evaluate NDs reported to the Vaccine Adverse Event Reporting System (VAERS) from 1991 through 2004 by date of receipt and by date of vaccine administration. The NDs examined included autism, mental retardation, and speech disorders. Statistical trend analysis was employed to evaluate the effects of removal of Thimerosal on the proportion of NDs reported to VAERS.

RESULTS:

There was a peak in the proportion of ND reports received by VAERS in 2001-2002 and in the proportion of ND reports by date of vaccine administration in 1998. There were significant reductions in the proportion of NDs reported to VAERS as Thimerosal was begun to be removed from childhood vaccines in the US from mid-1999 onwards.

CONCLUSIONS:

The present study provides the first epidemiological evidence showing that as Thimerosal was removed from childhood vaccines, the number of NDs has decreased in the US. The analysis techniques utilized attempted to minimize chance or bias/confounding. Additional research should be conducted to further evaluate the relationship between TCVs and NDs. This is especially true because the handling of vaccine safety data from the National Immunization Program of the CDC has been called into question by the Institute of Medicine of the National Academy of Sciences in 2005.”

“Dental amalgam, which contains 50% mercury by weight, has been used for at least 150 years. Because mercury is an acknowledged neurotoxin, concerns about the health effects of exposure to this chemical are widespread.”

“This in-depth review summarizes and interprets the available recent epidemiologic evidence on the relationship between occupational exposures and negative reproductive outcome among women workers.

METHODS:

The studies examined by the review include those published in the international scientific literature since 1990, and were identified through the search of relevant data banks using selected keywords.

RESULTS:

From the examination of studies dealing with exposures of women to chemical agents, pesticides, physical agents, ergonomic factors and stress, it appears that at present the evidence is sufficient to warrant the maximum protection of pregnant women to several well-documented occupational risk factors. These include exposures to anaesthetic gases, antineoplastic drugs, heavy metals, solvents, heavy physical work and irregular work schedules. For other work risks, such as exposure to non-ionizing radiation and psychosocial work stress, the evidence is often suggestive but not conclusive.

CONCLUSIONS:

Policy makers and health professionals should advise women and employers to avoid exposure to the well-known occupational risk factors, while epidemiologic research should pursue methodological improvements and provide more insight into the magnitude of exposures responsible for detrimental effects.”

“1) I am Professor of Chemistry/Biochemistry in the Department of Chemistry at the University of Kentucky. Throughout my career I have studied the effects of numerous compounds on the changes of the activity of enzymes, proteins and cellular function proteins and the relationship of these changes to disease states. In the past 14 years I have concentrated my research on the effects of mercury toxicity on human health. Specifically, I have researched and evaluated the contributions of dental amalgam, biologics and vaccines on the human body burden of mercury and organicmercury compounds and the potential effects of these compounds on specific enzymes and cells. Attached is a one page biography and an abbreviated copy of my Curriculum Vitae. The full CV is approximately twenty five pages and to save space will be provided upon request.
2) Mercury exposure to humans comes from various chemical forms such as elemental vapors, inorganic salts and organic-mercurials such as thimerosal and phenylmercury acetate (PMA). All chemical forms of mercury have been proven toxic at
relatively low levels.”

“OBJECTIVES:

High levels of transition metals such as iron, nickel, chromium, copper, and lead are closely related to free radical generation, lipid peroxidation, formation of DNA strand breaks, and tumor growth in cellular systems. In order to determine the correlation to malignant growth in humans, we investigated the accumulation of heavy metals in 20 breast cancer biopsies and compared the findings to the levels found in 8 healthy biopsies.

METHODS:

The concentration of transition metals in breast cancer and control biopsies was assessed by a standardized Atomic Absorption Spectrofotometry technique with acidic hydrolysis for sample preparation. Additionally, heavy metal analysis in control biopsies was also performed with an Inductive Coupled Plasma–Mass Spectroscopy technique. For statistical analysis of the results, the Mann-Whitney U Test was applied.

RESULTS:

A highly significant accumulation of iron (p<0.0001), nickel (p<0.00005), chromium (p<0.00005), zinc (p<0.00001), cadmium (p<0.005), mercury (p<0.005), and lead (p< 0.05) was found in the cancer samples when compared to the control group. Copper and silver showed no significant differences to the control group, whereas tin, gold, and palladium were not detectable in any biopsies.

CONCLUSIONS:

The data suggest that pathological accumulation of transition metals in breast tissue may be closely related to the malignant growth process.”

“Since elemental mercury is absorbed by dental professionals through direct skin contact or inhalation, the use of mercury in dental amalgam continues to be a controversial issue. In this study, the authors address the possible health risk of occupational exposure to mercury vapor in the dental office. The cytogenetic examination of leukocytes with alkaline comet assay and blood mercury levels with Atomic Absorption Spectrometer of dentists exposed to mercury vapor below 0.1mg/m(3) concentrations failed to find cytogenetic damage and related correlation. However, higher cytogenetic damage and blood mercury levels evaluated in controls from mercury intake by seafood consumption justifies additional study.”