title: Mercury in human brain, blood, muscle and toenails in relation to exposure: an autopsy study.
abstract: BACKGROUND
  The main forms of mercury (Hg) exposure in the general population are methylmercury (MeHg) from seafood, inorganic mercury (I-Hg) from food, and mercury vapor (Hg0) from dental amalgam restorations. While the distribution of MeHg in the body is described by a one compartment model, the distribution of I-Hg after exposure to elemental mercury is more complex, and there is no biomarker for I-Hg in the brain. The aim of this study was to elucidate the relationships between on the one hand MeHg and I-Hg in human brain and other tissues, including blood, and on the other Hg exposure via dental amalgam in a fish-eating population. In addition, the use of blood and toenails as biological indicator media for inorganic and organic mercury (MeHg) in the tissues was evaluated.
  
  
  METHODS
  Samples of blood, brain (occipital lobe cortex), pituitary, thyroid, abdominal muscle and toenails were collected at autopsy of 30 deceased individuals, age from 47 to 91 years of age. Concentrations of total-Hg and I-Hg in blood and brain cortex were determined by cold vapor atomic fluorescence spectrometry and total-Hg in other tissues by sector field inductively coupled plasma-mass spectrometry (ICP-SFMS).
  
  
  RESULTS
  The median concentrations of MeHg (total-Hg minus I-Hg) and I-Hg in blood were 2.2 and 1.0 microg/L, and in occipital lobe cortex 4 and 5 microg/kg, respectively. There was a significant correlation between MeHg in blood and occipital cortex. Also, total-Hg in toenails correlated with MeHg in both blood and occipital lobe. I-Hg in both blood and occipital cortex, as well as total-Hg in pituitary and thyroid were strongly associated with the number of dental amalgam surfaces at the time of death.
  
  
  CONCLUSIONS
  In a fish-eating population, intake of MeHg via the diet has a marked impact on the MeHg concentration in the brain, while exposure to dental amalgam restorations increases the I-Hg concentrations in the brain. Discrimination between mercury species is necessary to evaluate the impact on Hg in the brain of various sources of exposure, in particular, dental amalgam exposure.
authors.affiliation: Dental Biomaterials Adverse Reaction Unit, Department of Health/UNIFOB, Arstadveien 17, NO-5009 Bergen, Norway. Lars.Bjorkman@odont.uib.no
authors.forename: Lars
authors.initials: L
authors.lastname: Björkman
authors.forename: Birgitte F
authors.initials: BF
authors.lastname: Lundekvam
authors.forename: Torgils
authors.initials: T
authors.lastname: Laegreid
authors.forename: Bjørn I
authors.initials: BI
authors.lastname: Bertelsen
authors.forename: Inge
authors.initials: I
authors.lastname: Morild
authors.forename: Peer
authors.initials: P
authors.lastname: Lilleng
authors.forename: Birger
authors.initials: B
authors.lastname: Lind
authors.forename: Brita
authors.initials: B
authors.lastname: Palm
authors.forename: Marie
authors.initials: M
authors.lastname: Vahter
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001344:Autopsy; D015415:Biomarkers / Q000097:blood; D001774:Blood Chemical Analysis; D001923:Brain Chemistry; D003723:Dental Amalgam / Q000737:chemistry; D004032:Diet; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D008628:Mercury / Q000032:analysis* / Q000378:metabolism; D008875:Middle Aged; D009132:Muscles / Q000737:chemistry; D009262:Nails / Q000737:chemistry; D009664:Norway; D009941:Organomercury Compounds / Q000032:analysis / Q000378:metabolism; D012044:Regression Analysis; D017747:Seafood / Q000032:analysis; D013054:Spectrophotometry, Atomic
chemical_list: D015415:Biomarkers; D009941:Organomercury Compounds; D003723:Dental Amalgam; D008628:Mercury