EVISA Print | Glossary on | Contact EVISA | Sitemap | Home   
 Advanced search
The establishment of EVISA is funded by the EU through the Fifth Framework Programme (G7RT- CT- 2002- 05112).

Supporters of EVISA includes:

Mercury isotope fractionation provides new tool to trace the source of human exposure


Scientists agree that dental amalgam fillings slowly release mercury vapor into the mouth. About 80 percent of inhaled mercury vapor is absorbed into the bloodstream in the lungs and transported to the kidneys, where it is excreted in urine. In the absence of occupational exposure and because the mercury found in urine is almost entirely inorganic, total mercury concentrations in urine are commonly used as an indicator, or biomarker, for exposure to inorganic mercury from dental amalgams.

Since mercury exposure through the diet results mainly from the methylmercury as the main mercury species in fish, public health studies often make the assumption that mercury in hair (which is composed mostly of organic mercury) can be used to estimate exposure to organic mercury from a person's diet.

Results from a new study:
Researcher from the University of Michigan, who measured mercury isotopes in the hair and urine from 12 Michigan dentists, found that their urine contained a mix of mercury from two sources: the consumption of fish containing organic mercury and inorganic mercury vapor from the dentists' own amalgam fillings.

Mercury has seven stable (nonradioactive) isotopes. The scientists used the mercury isotopic distribution to distinguish between the two sources of exposure. Using this method to trace the metabolic pathway, the researchers could trace that part of methylmercury from fish that underwent a type of chemical breakdown in the body called demethylation. The demethylated mercury from fish contributes significantly to the amount of inorganic mercury in the urine.

The method relies on the effect called mass-independent fractionation that occurs during such metabolic reactions, in which different mercury isotopes react to form new compounds at slightly different rates. The specific isotopic patterns resulting from the mass-independcent fractionation was used as the chemical fingerprints that enabled them to distinguish between exposure to methylmercury from fish and mercury vapor from dental amalgam fillings.

"These results challenge the common assumption that mercury in urine is entirely derived from inhaled mercury vapor," said Laura Sherman, a postdoctoral research fellow in the Department of Earth and Environmental Sciences and lead author of a paper in the journal Environmental Science & Technology. "These data suggest that in populations that eat fish but lack occupational exposure to mercury vapor, mercury concentrations in urine may overestimate exposure to mercury vapor from dental amalgams. This is an important consideration for studies seeking to determine the health risks of mercury vapor inhalation from dental amalgams," said biogeochemist Joel D. Blum, a co-author of the paper and a professor in the Department of Earth and Environmental Sciences. In addition to Sherman and Blum, co-authors of the Environmental Science & Technology paper are Alfred Franzblau and Niladri Basu of the U-M School of Public Health.

The new study:

Laura S. Sherman, Joel D. Blum, Alfred Franzblau, Niladri Basu, New Insight into Biomarkers of Human Mercury Exposure Using Naturally Occurring Mercury Stable Isotopes, Environ. Sci. Technol., Article ASAP. DOI: 10.1021/es305250z

Related studies:

L. Laffont, J.E. Sonke, L. Maurice, S.L. Monrroy, J. Chincheros, D. Amouroux, P. Behra, Hg speciation and stable isotope signatures in human hair as a tracer for dietary and occupational exposure to mercury, Environ. Sci. Technol., 45/23 (2011) 9910–9916; DOI: 10.1021/es202353m.

R. Das, V.J.M. Salters, A.L. Odem, A case for in vivo mass-independent fractionation of mercury isotopes in fish, Geochem. Geophys. Geosystems, 10 (2009) Q11012. DOI: 10.1029/2009GC002617

K. Kritee, T. Barkay, J. Blum, Mass dependent stable isotope fractionation of mercury during mer mediated microbial degradation of monomethylmercury, Geochim. Cosmochim. Acta, 73 (2009) 1285–1296. doi: 10.1016/j.gca.2008.11.038

L. Bårregard, Biological monitoring of exposure to mercury vapor, Scand. J. Work, Environ. Health, 19/Sup.1 (1993) 45–49.
available at: http://www.sjweh.fi/show_abstract.php?abstract_id=1532

I. Suda, K. Hirayama, Degradation of methyl and ethyl mercury into inorganic mercury by hydroxyl radical produced from rat liver microsomes, Arch. Toxicol., 66 (1992) 398–402. DOI: 10.1007/BF02035129

A. Berglund, Estimation by a 24-h study of the daily dose of intra-oral mercury vapor inhaled after release from dental amalgam, J. Dent. Res., 69 (1990) 1646–1651. DOI: 10.1177/00220345900690100401

Related EVISA Resources

Link database: Mercury exposure through the diet
Link database: Occupational mercury exposure
Link database: Mercury and human health
Link database: Environmental cycling of mercury
Link database: Toxicity of Organo-mercury compounds
Link database: Research projects related to organo-mercury compounds

Related EVISA News

March 13, 2013: FDA rejects petition to change methylmercury standard in seafood
January 14, 2013: Mercury Levels in Humans and Fish Around the World Regularly Exceed Health Advisory Levels
December 9, 2012: Mercury in fish more dangerous than previously believed; Scientists urge for effective treaty ahead of UN talks
October 12, 2012: Prenatal mercury intake linked to ADHD
July 31, 2012: FDA Lands in Court Over Mercury in Fish
June 17, 2012: Factors Affecting Methylmercury Accumulation in the Food Chain
March 1, 2012: High levels of mercury in newborns likely from mothers eating contaminated fish
October 15, 2011: Mercury pollution in the Great Lakes region -- nearly forgotten, but not gone
August 16, 2010: Methylmercury: What have we learned from Minamata Bay?
August 21, 2009: USGS Study Reveals Mercury Contamination in Fish Nationwide
May 3, 2009: Ocean mercury on the rise
February 11, 2009: Mercury in Fish is a Global Health Concern
October 30, 2008: Precautionary approach to methylmercury needed
March 11, 2007: Methylmercury contamination of fish warrants worldwide public warning
October 9, 2006: Linking atmospheric mercury to methylmercury in fish
August 16, 2006: Mercury pollution threatens health worldwide, scientists say
June 8, 2006: Methylmercury in fish: Can you cook it out ? 
February 17, 2006: Study shows link between clear lakes and methylmercury contamination in fish
February 9, 2006: Study show high levels of mercury in women related to fish consumption
August 29, 2005: Is methyl mercury limiting the delight of seafood ? - To answer this question is a challenge for elemental speciation analysis
January 12, 2005: Number of fish meals is a good predictor for the mercury found in hair of environmental journalists
April 27, 2004: New kind of mercury found in fish
April 27, 2004: FDA/EPA recommends pregnant women to restrict their fish consumption because of methylmercury content

last time modified: March 22, 2013

Imprint     Disclaimer

© 2003 - 2010 by European Virtual Institute for Speciation Analysis ( EVISA )