Skip to main content
Environmental Health Perspectives logoLink to Environmental Health Perspectives
. 2002 May;110(5):523–526. doi: 10.1289/ehp.02110523

Inorganic mercury and methylmercury in placentas of Swedish women.

Karolin Ask 1, Agneta Akesson 1, Marika Berglund 1, Marie Vahter 1
PMCID: PMC1240842  PMID: 12003757

Abstract

We determined levels of inorganic mercury (I-Hg) and methylmercury in placentas from 119 Swedish women, not selected with respect to high exposure of mercury. Our objective was to relate placental Hg species with maternal and fetal blood concentrations and to evaluate possible associations with selenium. We performed the analyses using automated alkaline solubilization/reduction and cold-vapor atomic fluorescence spectrophotometry. I-Hg levels in placenta increased with an increasing number of maternal dental amalgam fillings (p < 0.001). Despite placental accumulation (median, 1.3 microg/kg; range, 0.18-6.7 microg/kg wet weight), a substantial fraction of maternal blood I-Hg, probably as Hg(0), reached the fetus. Although MeHg transferred easily to the fetus, it also accumulated in the placenta. On average, 60% of placental Hg was in the form of MeHg. The median concentration was 1.8 microg/kg (range, 0-6.2 microg/kg wet weight), more than twice the maternal blood concentration. We found significant associations between MeHg and selenium in both maternal and umbilical cord blood but not in the placenta. The associations were particularly obvious in freshwater fish consumers, probably reflecting that fish is a source of both MeHg and selenium. We found no correlations between I-Hg and selenium. This study increases the understanding of Hg, in its different forms, in human placenta and how they are related to maternal and fetal exposure.

Full Text

The Full Text of this article is available as a PDF (539.5 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Akesson A., Bjellerup P., Berglund M., Bremme K., Vahter M. Serum transferrin receptor: a specific marker of iron deficiency in pregnancy. Am J Clin Nutr. 1998 Dec;68(6):1241–1246. doi: 10.1093/ajcn/68.6.1241. [DOI] [PubMed] [Google Scholar]
  2. Akesson I., Schutz A., Attewell R., Skerfving S., Glantz P. O. Status of mercury and selenium in dental personnel: impact of amalgam work and own fillings. Arch Environ Health. 1991 Mar-Apr;46(2):102–109. doi: 10.1080/00039896.1991.9937436. [DOI] [PubMed] [Google Scholar]
  3. Aschner M., Lorscheider F. L., Cowan K. S., Conklin D. R., Vimy M. J., Lash L. H. Metallothionein induction in fetal rat brain and neonatal primary astrocyte cultures by in utero exposure to elemental mercury vapor (Hg0). Brain Res. 1997 Dec 5;778(1):222–232. doi: 10.1016/s0006-8993(97)01095-0. [DOI] [PubMed] [Google Scholar]
  4. Boadi W. Y., Shurtz-Swirski R., Barnea E. R., Urbach J., Brandes J. M., Yannai S. The influence of mercury on the secretion of human chorionic gonadotropin in superfused young placental tissue. Pharmacol Toxicol. 1992 Jul;71(1):19–23. doi: 10.1111/j.1600-0773.1992.tb00514.x. [DOI] [PubMed] [Google Scholar]
  5. Boadi W. Y., Urbach J., Brandes J. M., Yannai S. In vitro effect of mercury on enzyme activities and its accumulation in the first-trimester human placenta. Environ Res. 1992 Feb;57(1):96–106. doi: 10.1016/s0013-9351(05)80022-2. [DOI] [PubMed] [Google Scholar]
  6. Capelli R., Minganti V., Semino G., Bertarini W. The presence of mercury (total and organic) and selenium in human placentae. Sci Total Environ. 1986 Jan;48(1-2):69–79. doi: 10.1016/0048-9697(86)90154-3. [DOI] [PubMed] [Google Scholar]
  7. Cappon C. J., Smith J. C. Mercury and selenium content and chemical form in human and animal tissue. J Anal Toxicol. 1981 Mar-Apr;5(2):90–98. doi: 10.1093/jat/5.2.90. [DOI] [PubMed] [Google Scholar]
  8. Clarkson T. W. The toxicology of mercury. Crit Rev Clin Lab Sci. 1997;34(4):369–403. doi: 10.3109/10408369708998098. [DOI] [PubMed] [Google Scholar]
  9. Drasch G., Schupp I., Höfl H., Reinke R., Roider G. Mercury burden of human fetal and infant tissues. Eur J Pediatr. 1994 Aug;153(8):607–610. doi: 10.1007/BF02190671. [DOI] [PubMed] [Google Scholar]
  10. Frisk P., Yaqob A., Nilsson K., Carlsson J., Lindh U. Influence of selenium on mercuric chloride cellular uptake and toxicity indicating protection: studies on cultured K-562 cells. Biol Trace Elem Res. 2001 Sep;81(3):229–244. doi: 10.1385/BTER:81:3:229. [DOI] [PubMed] [Google Scholar]
  11. Grandjean P., Weihe P., Jørgensen P. J., Clarkson T., Cernichiari E., Viderø T. Impact of maternal seafood diet on fetal exposure to mercury, selenium, and lead. Arch Environ Health. 1992 May-Jun;47(3):185–195. doi: 10.1080/00039896.1992.9938348. [DOI] [PubMed] [Google Scholar]
  12. Grandjean P., Weihe P., White R. F., Debes F., Araki S., Yokoyama K., Murata K., Sørensen N., Dahl R., Jørgensen P. J. Cognitive deficit in 7-year-old children with prenatal exposure to methylmercury. Neurotoxicol Teratol. 1997 Nov-Dec;19(6):417–428. doi: 10.1016/s0892-0362(97)00097-4. [DOI] [PubMed] [Google Scholar]
  13. Kajiwara Y., Yasutake A., Adachi T., Hirayama K. Methylmercury transport across the placenta via neutral amino acid carrier. Arch Toxicol. 1996;70(5):310–314. doi: 10.1007/s002040050279. [DOI] [PubMed] [Google Scholar]
  14. Kuhnert P. M., Kuhnert B. R., Erhard P. Comparison of mercury levels in maternal blood, fetal cord blood, and placental tissues. Am J Obstet Gynecol. 1981 Jan 15;139(2):209–213. doi: 10.1016/0002-9378(81)90448-8. [DOI] [PubMed] [Google Scholar]
  15. Lutz E., Lind B., Herin P., Krakau I., Bui T. H., Vahter M. Concentrations of mercury, cadmium and lead in brain and kidney of second trimester fetuses and infants. J Trace Elem Med Biol. 1996 Jun;10(2):61–67. doi: 10.1016/S0946-672X(96)80013-7. [DOI] [PubMed] [Google Scholar]
  16. Nordberg M., Nordberg G. F. Toxicological aspects of metallothionein. Cell Mol Biol (Noisy-le-grand) 2000 Mar;46(2):451–463. [PubMed] [Google Scholar]
  17. Osman K., Akesson A., Berglund M., Bremme K., Schütz A., Ask K., Vahter M. Toxic and essential elements in placentas of Swedish women. Clin Biochem. 2000 Mar;33(2):131–138. doi: 10.1016/s0009-9120(00)00052-7. [DOI] [PubMed] [Google Scholar]
  18. Soria M. L., Sanz P., Martínez D., López-Artíguez M., Garrido R., Grilo A., Repetto M. Total mercury and methylmercury in hair, maternal and umbilical blood, and placenta from women in the Seville area. Bull Environ Contam Toxicol. 1992 Apr;48(4):494–501. doi: 10.1007/BF00199063. [DOI] [PubMed] [Google Scholar]
  19. Svensson B. G., Schütz A., Nilsson A., Akesson I., Akesson B., Skerfving S. Fish as a source of exposure to mercury and selenium. Sci Total Environ. 1992 Sep 11;126(1-2):61–74. doi: 10.1016/0048-9697(92)90484-a. [DOI] [PubMed] [Google Scholar]
  20. Tsuchiya H., Mitani K., Kodama K., Nakata T. Placental transfer of heavy metals in normal pregnant Japanese women. Arch Environ Health. 1984 Jan-Feb;39(1):11–17. doi: 10.1080/00039896.1984.10545827. [DOI] [PubMed] [Google Scholar]
  21. Urbach J., Boadi W., Brandes J. M., Kerner H., Yannai S. Effect of inorganic mercury on in vitro placental nutrient transfer and oxygen consumption. Reprod Toxicol. 1992;6(1):69–75. doi: 10.1016/0890-6238(92)90023-m. [DOI] [PubMed] [Google Scholar]
  22. Vahter M., Akesson A., Lind B., Björs U., Schütz A., Berglund M. Longitudinal study of methylmercury and inorganic mercury in blood and urine of pregnant and lactating women, as well as in umbilical cord blood. Environ Res. 2000 Oct;84(2):186–194. doi: 10.1006/enrs.2000.4098. [DOI] [PubMed] [Google Scholar]
  23. Vahter M., Mottet N. K., Friberg L., Lind B., Shen D. D., Burbacher T. Speciation of mercury in the primate blood and brain following long-term exposure to methyl mercury. Toxicol Appl Pharmacol. 1994 Feb;124(2):221–229. doi: 10.1006/taap.1994.1026. [DOI] [PubMed] [Google Scholar]
  24. Warfvinge K. Mercury distribution in the neonatal and adult cerebellum after mercury vapor exposure of pregnant squirrel monkeys. Environ Res. 2000 Jun;83(2):93–101. doi: 10.1006/enrs.1999.4013. [DOI] [PubMed] [Google Scholar]
  25. Watanabe C., Yin K., Kasanuma Y., Satoh H. In utero exposure to methylmercury and Se deficiency converge on the neurobehavioral outcome in mice. Neurotoxicol Teratol. 1999 Jan-Feb;21(1):83–88. doi: 10.1016/s0892-0362(98)00036-1. [DOI] [PubMed] [Google Scholar]
  26. Watanabe C., Yoshida K., Kasanuma Y., Kun Y., Satoh H. In utero methylmercury exposure differentially affects the activities of selenoenzymes in the fetal mouse brain. Environ Res. 1999 Apr;80(3):208–214. doi: 10.1006/enrs.1998.3889. [DOI] [PubMed] [Google Scholar]
  27. Yang J., Jiang Z., Wang Y., Qureshi I. A., Wu X. D. Maternal-fetal transfer of metallic mercury via the placenta and milk. Ann Clin Lab Sci. 1997 Mar-Apr;27(2):135–141. [PubMed] [Google Scholar]
  28. Yee S., Choi B. H. Oxidative stress in neurotoxic effects of methylmercury poisoning. Neurotoxicology. 1996 Spring;17(1):17–26. [PubMed] [Google Scholar]

Articles from Environmental Health Perspectives are provided here courtesy of National Institute of Environmental Health Sciences

RESOURCES