Mercury burden of human fetal and infant tissues
TL;DR: The toxicological relevance of the unexpected high Hg-K of older infants from mothers with higher numbers of dental amalgam fillings is discussed.
Abstract: The total mercury concentrations in the liver (Hg-L), the kidney cortex (Hg-K) and the cerebral cortex (Hg-C) of 108 children aged 1 day-5 years, and the Hg-K and Hg-L of 46 fetuses were determined. As far as possible, the mothers were interviewed and their dental status was recorded. The results were compared to mercury concentrations in the tissues of adults from the same geographical area. The Hg-K (n = 38) and Hg-L (n = 40) of fetuses and Hg-K (n = 35) and Hg-C (n = 35) of older infants (11–50 weeks of life) correlated significantly with the number of dental amalgam fillings of the mother. The toxicological relevance of the unexpected high Hg-K of older infants from mothers with higher numbers of dental amalgam fillings is discussed.
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568 citations
TL;DR: Considerable attention was given in this review to pediatric methylmercury exposure and neurodevelopment because it is the most thoroughly investigated Hg species.
477 citations
Cites background from "Mercury burden of human fetal and i..."
...In humans, Drasch et al. (1994) found significant positive correlations between I-Hg concentrations in the liver and kidneys of both fetuses and infants and the number of maternal teeth with amalgam fillings....
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...Dyall-Smith and Scurry (1990) reported elevated levels of Hg in blood and urine, facial mercury pigmentation changes, and possible neuropsychiatric involvement in a woman who regularly used a 17....
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TL;DR: Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice.
435 citations
TL;DR: The debate about mercury is focused on 1) additional research that should be sought and 2) defining the principal issues that public policy makers face, as well as reviewing what is known about mercury neurotoxicity and neurodevelopmental risk.
Abstract: Mercury is ubiquitous in the global environment, ensuring universal exposure. Some forms of mercury are especially neurotoxic, including clinical signs at high doses. However, typical human exposures occur at low to moderate doses. Only limited data about neurotoxicity at low doses are available, and scientists differ in their interpretation. Dose-response data on neurodevelopment are particularly limited. Despite or perhaps because of the lack of sufficient or consistent scientific data, public concern about a link between mercury exposure and developmental disabilities has been rising. After reviewing the data, the US Environmental Protection Agency proposed a reference dose (an estimate of a daily dose that is likely to be without a risk of adverse effects over a lifetime) for methyl mercury that is substantially lower than previous guidelines from the World Health Organization, the US Agency for Toxic Substances and Disease Registry, and the US Food and Drug Administration. Some questions have been raised about the Environmental Protection Agency's guidelines, but the issue remains unresolved. Meanwhile, consumer groups have raised questions about the potential link between mercury exposure and autism spectrum disorders as well as other adverse neurodevelopmental outcomes. This hypothesis has prompted some parents to seek regulatory, legal, or medical remedies in the absence of firm evidence. This article reviews what is known about mercury neurotoxicity and neurodevelopmental risk. Our intent is to focus the debate about mercury on 1) additional research that should be sought and 2) defining the principal issues that public policy makers face.
289 citations
TL;DR: Mercury has a long and interesting history deriving from its use in medicine and industry, with the resultant toxicity produced, and the disproved relationship between vaccines and autism related to the presence of the mercury-containing preservative, thimerosal.
230 citations
References
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TL;DR: The essential elements that remain within narrow concentration limits throughout adult life suggest the presence of an efficient homeostatic mechanism for their regulation in the brain, while those that are altered with age suggest modifications in control mechanisms or altered relationships with other elements.
218 citations
TL;DR: The embryopathic and fetal toxic effects of mercury in general are identified while emphasizing the greater toxicity of methylmercury compounds.
192 citations
"Mercury burden of human fetal and i..." refers background in this paper
...The placental transfer of mercury from the mother to the fetus depends on the maternal mercury" burden [7, 10, 12, 21]....
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TL;DR: Accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained, and Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered.
Abstract: In humans, the continuous release of Hg vapor from dental amalgam tooth restorations is markedly increased for prolonged periods after chewing. The present study establishes a time-course distribution for amalgam Hg in body tissues of adult and fetal sheep. Under general anesthesia, five pregnant ewes had twelve occlusal amalgam fillings containing radioactive 203Hg placed in teeth at 112 days gestation. Blood, amniotic fluid, feces, and urine specimens were collected at 1- to 3-day intervals for 16 days. From days 16-140 after amalgam placement (16-41 days for fetal lambs), tissue specimens were analyzed for radioactivity, and total Hg concentrations were calculated. Results demonstrate that Hg from dental amalgam will appear in maternal and fetal blood and amniotic fluid within 2 days after placement of amalgam tooth restorations. Excretion of some of this Hg will also commence within 2 days. All tissues examined displayed Hg accumulation. Highest concentrations of Hg from amalgam in the adult occurred in kidney and liver, whereas in the fetus the highest amalgam Hg concentrations appeared in liver and pituitary gland. The placenta progressively concentrated Hg as gestation advanced to term, and milk concentration of amalgam Hg postpartum provides a potential source of Hg exposure to the newborn. It is concluded that accumulation of amalgam Hg progresses in maternal and fetal tissues to a steady state with advancing gestation and is maintained. Dental amalgam usage as a tooth restorative material in pregnant women and children should be reconsidered.
91 citations
TL;DR: Regression analysis of data from the pituitary glands and occipital cortices of dental staff indicated the accumulation of Se at a rough stoichiometric ratio of 1:1 with Hg; it is assumed that this corresponds to biologically available Se.
Abstract: Mercury (Hg) and selenium (Se) concentrations were determined by radiochemical neutron activation analysis in samples from the pituitary glands, occipital cortices, renal cortices, abdominal muscles, and thyroid glands of cadavers. Samples were retrieved from dental staff occupationally exposed to Hg and from the general population. Increased concentrations of both Hg and Se in samples from dental staff showed that Se accumulated together with Hg. Regression analysis of data from the pituitary glands and occipital cortices of dental staff indicated the accumulation of Se at a rough stoichiometric ratio of 1:1 with Hg. The same stoichiometric ratio between the elements was seen in the renal cortices from the general population. The regression analysis showed that a substantial fraction of Se was not associated with Hg; it is assumed that this corresponds to biologically available Se. Concentrations of biologically available Se decreased with advancing age in the pituitary gland, but not in other organs, and varied appreciably between organs.
77 citations
TL;DR: DMPS can be used to increase the urinary excretion of mercury and thus increase the significance and reliability of this measure of mercury exposure or burden, especially in cases of micromercurialism.
Abstract: There is considerable controversy as to whether dental amalgams may cause systemic health effects in humans because they liberate elemental mercury. Most such amalgams contain as much as 50% metallic mercury. To determine the influence of dental amalgams on the mercury body burden of humans, we have given volunteers, with and without amalgams in their mouth, the sodium salt of 2,3-dimercaptopropane-1-sulfonic acid (DMPS), a chelating agent safely used in the Soviet Union and West Germany for a number of years. The diameters of dental amalgams of the subjects were determined to obtain the amalgam score. Administration of 300 mg DMPS by mouth increased the mean urinary mercury excretion of the amalgam group from 0.70 to 17.2 micrograms and that of the nonamalgam group from 0.27 to 5.1 micrograms over a 9-h period. Two-thirds of the mercury excreted in the urine of those with dental amalgams appears to be derived originally from the mercury vapor released from their amalgams. Linear regression analysis indicated a highly significant positive correlation between the mercury excreted in the urine 2 h after DMPS administration and the dental amalgam scores. DMPS can be used to increase the urinary excretion of mercury and thus increase the significance and reliability of this measure of mercury exposure or burden, especially in cases of micromercurialism.
75 citations
"Mercury burden of human fetal and i..." refers background in this paper
...Recent investigations [1, 5] have shown in humans that dental amalgam fillings are the principal source of the mercury burden of adults, at least in geographic areas with a moderate consumption of fish and seafood....
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...At the present time, the toxicity of mercury vapour from dental amalgams is being assessed through a variety of investigations [1]; however, the toxicological consequence of the relatively high mercury concentrations in the renal cortex of infants, as found in the present study, has not been de te I~ned ....
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