Mercury

BACKGROUND:

Some authors have reported higher blood mercury (Hg) levels in persons with autism, relative to unaffected controls.

OBJECTIVES:

We compared blood total Hg concentrations in children with autism or autism spectrum disorder (AU/ASD) and typically developing (TD) controls in population-based samples, and determined the role of fish consumption in differences observed.

METHODS:

The Childhood Autism Risk from Genetics and the Environment (CHARGE) Study enrolled children 2-5 years of age. After diagnostic evaluation, we analyzed three groups: AU/ASD, non-AU/ASD with developmental delay (DD), and population-based TD controls. Mothers were interviewed about household, medical, and dietary exposures. Blood Hg was measured by inductively coupled plasma mass spectrometry. Multiple linear regression analysis was conducted (n = 452) to predict blood Hg from diagnostic status controlling for Hg sources.

RESULTS:

Fish consumption strongly predicted total Hg concentration. AU/ASD children ate less fish. After adjustment for fish and other Hg sources, blood Hg levels in AU/ASD children were similar to those of TD children (p = 0.75); this was also true among non-fish eaters (p = 0.73). The direct effect of AU/ASD diagnosis on blood Hg not through the indirect pathway of altered fish consumption was a 12% reduction. DD children had lower blood Hg concentrations in all analyses. Dental amalgams in children with gum-chewing or teeth-grinding habits predicted higher levels.

CONCLUSIONS:

After accounting for dietary and other differences in Hg exposures, total Hg in blood was neither elevated nor reduced in CHARGE Study preschoolers with AU/ASD compared with unaffected controls, and resembled those of nationally representative samples.”

“This report looks at the literature pertaining to the most important yet controversial restorative material in the history of dentistry, dental amalgam. It reviews utilization patterns of the material in the largest publicly insured program in Canada, the Non-Insured Health Benefits Program (NIHB), and evaluates specific mercury levels of the Canadian population.
As a result of the intense debate on possible adverse health effects of amalgam restorations, individuals who related their symptoms to the presence of dental amalgam have received increased attention. However, extensive research conducted worldwide has failed to document a link between the presence of amalgam fillings and the development of systemic diseases.”

“OBJECTIVES:

The Norwegian Mother and Child Cohort Study (MoBa) started in 1999 to identify environmental factors that could be involved in mechanisms leading to disease. Questions have been raised about potential risks to the fetus from prenatal exposure to mercury from amalgam fillings in pregnant women. The aim of the present study was to identify factors potentially associated with amalgam fillings in pregnant women participating in the Norwegian Mother and Child Cohort Study (MoBa). An additional aim was to obtain information about dental treatment in the cohort.

METHODS:

Total of 67,355 pregnancies from the MoBa study were included in the present study. Information regarding age, education, smoking habits, alcohol consumption, weight, and height for the women was obtained from a questionnaire that was filled in at the 17th week of pregnancy. In another questionnaire, which was sent to all participants in the 30th week of pregnancy, the women reported types of dental treatment during pregnancy, total number of teeth, and number of teeth with amalgam fillings. The self-assessed number of teeth and number of teeth with amalgam fillings were validated in an external sample of 97 women of childbearing age.

RESULTS:

Odds ratio for having more than 12 teeth with amalgam fillings increased considerably with age. Other significant risk factors for having high exposure to amalgam were low education, high body mass index (BMI), and smoking during pregnancy. Women with the lowest levels of education had a twofold increased odds ratio of having more than 12 teeth filled with amalgam compared with women who had more than 4 years of university studies. According to the results from the validation of self-assessed number of teeth with amalgam fillings, the information obtained was reliable.”

“HgCl2 is a known environemental neurotoxin, but is also used as preservative in vaccines as thimerosal containing ethyl mercury covalently linked to thiosalicylate. We recently reported that mercury choloride (HgCl(2)) can stimulate human mast cells to release vascular endothelial growth factor (VEGF), which is also vasoactive and pro-inflammatory. Here we show that thimerosal induces significant VEGF release from human leukemic cultured LAD2 mast cells (at 1 microM 326 ± 12 pg/106 cells and 335.5 ± 12 pg/106 cells at 10 microM) compared to control cells (242 ± 21 pg/106 cells, n=5, p less than 0.05); this effect is weaker than that induced by HgCl2 at 10 microM (448 ± 14 pg/106 cells) (n=3, p less than 0.05). In view of this finding, we hypothesize that the thiosalicylate component of thimerosal may have an inhibitory effect on VEGF release. Thimerosal (10 microM) added together with the peptide Substance P (SP) at 2 microM, used as a positive control, reduced VEGF release by 90 percent. Methyl thiosalicylate (1 or 10 microM) added with either SP or HgCl2 (10 microM) inhibited VEGF release by 100 percent, while sodium salicylate or ibuprofen had no effect. Pretreatment for 10 min with the flavonoid luteolin (0.1 mM) before HgCl2 or thimerosal compeletly blocked their effect. Luteolin and methyl thiosalicylate may be useful in preventing mercury-induced toxicity.”

“Chemical exposure during pregnancy is potentially harmful to the developing fetus, as the placenta cannot protect against heavy metals such as lead and mercury (1–4). Cord blood mercury levels have been associated with childhood cognitive function (3,4). High levels of lead exposure during pregnancy have been associated with adverse birth outcomes and, in some studies, with lower cognitive function test scores in childhood (3); relatively low lead levels have recently been associated with a small risk of decreased birthweight (5). While intervention for pregnant women with blood lead levels greater than or equal to 5 μg/dL has been recommended (6,7), no comparable recommendation for blood mercury in pregnant women has been established. This report presents geometric mean lead and mercury blood levels of pregnant women in the United States based on using the 2003–2008 National Health and Nutrition Examination Surveys (NHANES). Throughout this report, the term mean refers to the geometric mean.”

“Mercury-containing dental amalgam is known to be a source of human exposure to mercury. We have explored the use of electron yield Hg L(III) X-ray absorption spectroscopy to characterize the chemical nature of dental amalgam surfaces. We find that the method is practical and that it shows extensive mercury depletion in the surface of the aged amalgam with significant differences between old and fresh amalgam surfaces. Whereas the fresh amalgam gives spectra that are typical of metallic mercury, the aged amalgam is predominantly beta-mercuric sulfide. The toxicological implications of these results are discussed.”

“Autism spectrum disorders (ASDs) may result from a combination of genetic/biochemical susceptibilities in the form of a reduced ability to excrete mercury and/or increased environmental exposure at key developmental times. Urinary porphyrins and transsulfuration metabolites in participants diagnosed with an ASD were examined. A prospective, blinded study was undertaken to evaluate a cohort of 28 participants with an ASD diagnosis for Childhood Autism Rating Scale (CARS) scores, urinary porphyrins, and transsulfuration metabolites. Testing was conducted using Vitamin Diagnostics, Inc. (CLIA-approved) and Laboratoire Philippe Auguste (ISO-approved). Participants with severe ASDs had significantly increased mercury intoxication-associated urinary porphyrins (pentacarboxyporphyrin, precoproporphyrin, and coproporphyrin) in comparison to participants with mild ASDs, whereas other urinary porphyrins were similar in both groups. Significantly decreased plasma levels of reduced glutathione (GSH), cysteine, and sulfate were observed among study participants relative to controls. In contrast, study participants had significantly increased plasma oxidized glutathione (GSSG) relative to controls. Mercury intoxication-associated urinary porphyrins were significantly correlated with increasing CARS scores and GSSG levels, whereas other urinary porphyrins did not show these relationships. The urinary porphyrin and CARS score correlations observed among study participants suggest that mercury intoxication is significantly associated with autistic symptoms. The transsulfuration abnormalities observed among study participants indicate that mercury intoxication was associated with increased oxidative stress and decreased detoxification capacity.”

“OBJECTIVES:

Exposure to mercury, a risk factor for neuro-developmental toxicity, was evaluated in the Czech Republic by performing mercury determination using human hair as an indicator.

METHODS:

Hair samples from Czechs (n=311; 2-66 years old) were analyzed for mercury content. Total mercury was analysed by mercury analyzer AMA 254.

RESULTS:

The highest total mercury content found in sampled hair was 3.55 microg/g and the lowest content was 0.015 microg/g. No correlation was found between the mercury levels in the sampled hair and the subject’s age, gender, and the amount of amalgam fillings. A total of 38 hair samples were analyzed for methylmercury content.

CONCLUSION:

The results show a positive correlation between the total mercury content in human hair and the consumption of marine and freshwater fish. Hair are a very good indicator of fish consumption.”

“This collective review focuses on three major factors that influence the incidences of multiple sclerosis (MS) to include ultraviolet radiation (UVR), vitamin D3 supplementation, and vitamin D receptor gene (VDRG) polymorphisms. In general, the rate of MS increases with latitude. Individuals tend to carry their original risk with them if they migrate to a different latitude after adolescence. It is important to emphasize that UVR increases the synthesis of vitamin D3, which has a known immune suppressant action via the VDRG. Clinical studies have pointed out that vitamin D deficiency may exacerbate the development of MS. Because vitamin D3 is an inhibitor of MS, providing supplemental D3 for individuals at risk for MS should be mandatory. There is unanimous agreement that exposure to UVR and vitamin D3 supplementation can reduce the incidence of MS. Although there is debate regarding the association of MS with the use of silver mercury fillings, there is general agreement throughout the world that there is a need for dental-patient informed-consent brochures for all dentists who use dental restoration materials. For the dentists who remove silver mercury amalgam from their patients, there is a uniform international agreement that all dental offices should use reliable debris collection devices that prevent pollution of our environment.”

OBJECTIVES:
The technique of MRI, using powerful magnets, plays an important role in the diagnosis of diseases of the head and neck without any ionizing radiation. Because of the potential hazard imposed by the presence of ferromagnetic metals, patients with implanted metallic objects are excluded from MRI. However, amalgam restorations seem to be safe. The purpose of this study was to evaluate microleakage of amalgam restorations following MRI.

METHODS:
63 human freshly extracted premolars were divided into 3 groups based on 3 high-copper amalgams used to restore standard class V preparations on both buccal and lingual surfaces. Three different amalgam materials were used: Cinalux, GS-80 and Vivacap. The teeth were transferred into saline solution for 2 months at room temperature and then sectioned mesiodistally. MRI was randomly applied to one half of each section, and the other half was kept as a control. Following MRI, all specimens were immersed in a dye solution, sectioned and scored for any microleakage using a stereomicroscope.

RESULTS:
Differences in microleakage within each group following MRI were significant in the GS-80 and Vivacap groups but not in the Cinalux group. However, there was no significant difference between the three groups regarding the microleakage score.

CONCLUSIONS:
The results of this study suggest that MRI is not a completely safe technique in patients with amalgam restorations. It was shown that the main effect of fields led to the appearance of thermoelectromagnetic convection, which is responsible for the enhancement of the diffusion process, grain boundary migration and vacancy formation resulting in microleakage.