Mercury

“The prevalence of autism in the US has risen from 1 in approximately 2500 in the mid-1980s to 1 in approximately 300 children in the mid-1990s. The purpose of this study was to evaluate whether mercury from thimerosal in childhood vaccines contributed to neurodevelopmental disorders. Neurodevelopmental disorder dose-response curves for increasing mercury doses of thimerosal in childhood vaccines were determined based upon examination of the Vaccine Adverse Events Reporting System (VAERS) database and the 2001 US’ Department of Education Report. The instantaneous dosage of mercury children received in comparison to the Food and Drug Administration (FDA)’s maximum permissible dose for the oral ingestion of methylmercury was also determined. The dose-response curves showed increases in odds ratios of neurodevelopmental disorders from both the VAERS and US Department of Education data closely linearly correlated with increasing doses of mercury from thimerosal-containing childhood vaccines and that for overall odds ratios statistical significance was achieved. Similar slopes and linear regression coefficients for autism odds ratios in VAERS and the US Department of Education data help to mutually validate each other. Controls employed in the VAERS and US Department of Education data showed minimal biases. The evidence presented here shows that the occurrence of neurodevelopmental disorders following thimerosal-containing childhood vaccines does not appear to be coincidental.”

“We studied exposure to methyl mercury (MeHg) in Swedish pregnant women (total mercury [T-Hg] in hair) and their fetuses (MeHg in cord blood) in relation to fish intake. The women were recruited at antenatal care clinics in late pregnancy to participate in an exposure study of environmental pollutants. Fish consumption was evaluated using food frequency questionnaires including detailed questions on fish consumption. In addition, we determined inorganic mercury (I-Hg) and selenium (Se) in cord blood. On average, the women consumed fish (all types) 6.7 times/month (range 0-25 times/month) during the year they became pregnant. They reported less consumption of freshwater fish–species that might contain high concentrations of MeHg–during than before pregnancy. T-Hg in maternal hair (median 0.35 mg/kg; range 0.07-1.5 mg/kg) was significantly associated (R2 = 0.53; p < 0.001) with MeHg in cord blood (median 1.3 microg/L; range 0.10-5.7 microg/L). Both hair T-Hg and cord blood MeHg increased with increasing consumption of seafood (r = 0.41; p < 0.001 and r = 0.46; p < 0.001, respectively). Segmental hair analysis revealed that T-Hg closer to the scalp was lower and more closely correlated with MeHg in cord blood than T-Hg levels in segments corresponding to earlier in pregnancy. We found a weak association between Se (median 86 microg/L; range 43-233 microg/L) and MeHg in cord blood (r = 0.26; p = 0.003), but no association with fish consumption. I-Hg in cord blood (median 0.15 microg/L; range 0.03-0.53 microg/L) increased significantly with increasing number of maternal dental amalgam fillings.”

“Dental amalgam is 50% mercury (Hg) by weight and its continued use as the preferred dental restorative material in Canada constitutes a significant source of Hg to municipal sewers and ultimately to the environment. The Recent CCME Canada Wide Standard on Hg for Dental Amalgam Waste provides a national basis for managing the Hg-containing wastes from dental clinics and ultimately reducing what is currently considered to be the single largest source of Hg to municipal sewers. This paper briefly reviews the background and rationale that lead to the need for and ratification of that Canada Wide Standard.”

“The use of DMPS as a diagnostic tool in patients with symptoms allegedly caused by mercury from dental amalgam fillings is disputed. We have previously shown that the mercury concentrations in urine cannot be used in such a way.In the present study, we wished to evaluate the effect on blood mercury levels (B-Hg) following intravenously injected DMPS in four groups of subjects: 19 controls without amalgam experience; 21 healthy controls with amalgam fillings; 20 patients with self-reported symptoms from existing dental amalgams; and 20 patients who had removed amalgam fillings.A single dose of DMPS (2 mgykg) was injected.Blood samples were collected prior to the injection and after 15, 30, 120 min, and after 24 h, and mercury was analyzed by cold vapor atomic absorption spectrophotometry.All groups showed an initial drop of 24 to 30% in the blood levels, approaching baseline values (2.5–5.5 mgyl) after 2 h.The subjects with no amalgam experience had the lowest mercury values. There was no significant difference between the three groups with such experience.Ther e were no significant differences between the two groups with amalgam fillings present.Patients with symptoms allegedly caused by amalgam were not different from the control groups.Ther e were indications that part of the urinary mercury excreted during the first 30 min originated from blood.”

“There is a concern on the part of community that adverse health consequences by thimerosal, one of mercurial preservatives, may occur among infants during immunization schedule although it is generally believed that the safety of thimerosal use for humans has been established. Therefore, the effect of thimerosal on K562 human leukemia cells was compared with that of methylmercury. Incubation of K562 cells with thimerosal at micromolar concentrations for 72 hr inhibited the growth and increased the population of shrunken cells in a concentration-dependent manner. Significant changes in growth and population were seen in the case of 3 .MU.M thimerosal. The population of hypodiploidal cells was also greatly increased by 3 .MU.M thimerosal, suggesting that the thimerosal-induced apoptosis of K562 cells. The complete inhibition of growth was observed in the cells incubated with 10 .MU.M thimerosal. The potency of thimerosal to affect K562 cells was similar to that of methylmercury. Therefore, the attention may be paid on the use of thimerosal as a preservative in vaccines for infants.”

“Reported rates of autism have increased sharply in the United States and the United Kingdom. One possible factor underlying these increases is increased exposure to mercury through thimerosal-containing vaccines, but vaccine exposures need to be evaluated in the context of cumulative exposures during gestation and early infancy. Differential rates of postnatal mercury elimination may explain why similar gestational and infant exposures produce variable neurological effects. First baby haircut samples were obtained from 94 children diagnosed with autism using Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM IV) criteria and 45 age- and gender-matched controls. Information on diet, dental amalgam fillings, vaccine history, Rho D immunoglobulin administration, and autism symptom severity was collected through a maternal survey questionnaire and clinical observation. Hair mercury levels in the autistic group were 0.47 ppm versus 3.63 ppm in controls, a significant difference. The mothers in the autistic group had significantly higher levels of mercury exposure through Rho D immunoglobulin injections and amalgam fillings than control mothers. Within the autistic group, hair mercury levels varied significantly across mildly, moderately, and severely autistic children, with mean group levels of 0.79, 0.46, and 0.21 ppm, respectively. Hair mercury levels among controls were significantly correlated with the number of the mothers’ amalgam fillings and their fish consumption as well as exposure to mercury through childhood vaccines, correlations that were absent in the autistic group. Hair excretion patterns among autistic infants were significantly reduced relative to control. These data cast doubt on the efficacy of traditional hair analysis as a measure of total mercury exposure in a subset of the population. In light of the biological plausibility of mercury’s role in neurodevelopmental disorders, the present study provides further insight into one possible mechanism by which early mercury exposures could increase the risk of autism.”

“Since 1992, in Baden-Württemberg, ten-year old children have been surveyed in the project “Sentinel Health Departments” to study their exposure to environmental pollutants and possible health effects. In the four study areas 1200 children have been investigated every year initially, since 1996 every second year. The data for mercury in body fluids are reported here. The decrease in the body burden of mercury as a result of the declining usage of dental amalgam fillings, was been verified. In 1992/93, of all the children who had been surveyed, the 95 percentile for the body burden of mercury was 3.1 microg/l and in 2000/01 1.35 microg/l. Also to be discussed is the reason why mercury-based cosmetic ointments seriously exceed the HBM-II-intervention-value. Because of using these ointments, concentrations of mercury in urine up to 1400 microg/l were found. A study within the project “Sentinel Health Departments” compared the concentrations of mercury in the urine of adults with those in blood and salvia. The results support the opinion that mercury in urine is appropriate for estimating the mercury uptake from dental amalgam fillings. It can be assumed that these results reflect the situation in the entire Federal Republic of Germany. The ten years’ experience confirms that the concept of the “Sentinel Health Departments” is excellently suited to obtain data relevant for environmental health of children. Environmental health protection and the essential gathering of data for future health observation in Baden-Württemberg.”

“Thimerosal is an organic mercurial compound used as a preservative in biomedical preparations. Little is known about the reactions of human neuronal and skin cells to its micro- and nanomolar concentrations, which can occur after using thimerosal-containing products. A useful combination of fluorescent techniques for the assessment of thimerosal toxicity is introduced. Short-term thimerosal toxicity was investigated in cultured human cerebral cortical neurons and in normal human fibroblasts. Cells were incubated with 125-nM to 250-microM concentrations of thimerosal for 45 min to 24 h. A 4′, 6-diamidino-2-phenylindole dihydrochloride (DAPI) dye exclusion test was used to identify nonviable cells and terminal transferase-based nick-end labeling (TUNEL) to label DNA damage. Detection of active caspase-3 was performed in live cell cultures using a cell-permeable fluorescent caspase inhibitor. The morphology of fluorescently labeled nuclei was analyzed. After 6 h of incubation, the thimerosal toxicity was observed at 2 microM based on the manual detection of the fluorescent attached cells and at a 1-microM level with the more sensitive GENios Plus Multi-Detection Microplate Reader with Enhanced Fluorescence. The lower limit did not change after 24 h of incubation. Cortical neurons demonstrated higher sensitivity to thimerosal compared to fibroblasts. The first sign of toxicity was an increase in membrane permeability to DAPI after 2 h of incubation with 250 microM thimerosal. A 6-h incubation resulted in failure to exclude DAPI, generation of DNA breaks, caspase-3 activation, and development of morphological signs of apoptosis. We demonstrate that thimerosal in micromolar concentrations rapidly induce membrane and DNA damage and initiate caspase-3-dependent apoptosis in human neurons and fibroblasts. We conclude that a proposed combination of fluorescent techniques can be useful in analyzing the toxicity of thimerosal.”

“The effect of the sulfhydryl reagent, thimerosal (TMS) on meiosis resumption in germinal vesicle (GV)-stage denuded mouse oocytes was studied. It irreversibly inhibits both GV breakdown (GVBD) and the first polar body (pb1) extrusion in concentration- and time-dependent manners, the most striking result being the very early and narrow temporal window during which denuded primary oocytes released from their follicle are susceptible to a pulse of the drug. This inhibition is bypassed by dithiothreitol (DTT) with an efficiency declining with time, while thiosalicylic acid (TA), an analog of TMS devoid of the mercury atom, has no effect on meiosis reinitiation. These results strongly suggest that the inhibitory effect of TMS is a consequence of its sulfhydryl group oxidising activity. The molecular target(s) of this inhibitory oxidation should however be identified. In contrast to DTT, okadaic acid (OA), known to bypass the inhibitory effect of drugs interfering with protein kinase activities, only induces chromatin condensation and GVBD in TMS-pulsed oocytes with a delay of about 8 hr as compared to the control situation. This confirms that a very early thiol oxidation induced by TMS exerts a much more dramatic effect on resumption on meiosis than any pharmacological manipulation of protein kinase activities leading to activation of MPF.”

“A pulse of thimerosal (TMS), a sulfhydryl reagent, induces an instantaneous, complete and long-lasting microtubule interphasic network disassembly in mouse primary oocytes, correlated with the irreversible inhibition of meiosis reinitiation This inhibition is bypassed by dithiothreitol (DTT) while thiosalicylic acid, an analog of TMS, does induce neither microtubules depolymerisation nor inhibition of reinitiation and resumption of meiosis. This strongly suggests that the dramatic and pleiotropic inhibitory effect of TMS is specifically related to its sulfhydryl group oxidising activity of critical molecules among which tubulin. In contrast to DTT, okadaic acid (OA), known to bypass the inhibitory effect of drugs interfering with protein kinase activities, induces a late chromatin condensation and GVBD in TMS-pulsed oocytes as compared to the control situation, with no significant concomitant microtubule assembly. These cytological features are suggested to be indirectly induced by a late MAPK activation and confirm that a very early thiol oxidation induced by TMS exerts a much more dramatic effect on resumption of meiosis than any pharmacological manipulation of protein kinase activities leading to activation of MPF. Finally, taxol was shown to promote tubulin polymerisation even when microtubules were irreversibly disassembled by thiol oxidation but fails to restore the ability to undergo maturation.”