title: Prenatal exposure to dental amalgam: evidence from the Seychelles Child Development Study main cohort.
abstract: BACKGROUND
  Dental amalgams contain approximately 50 percent metallic mercury and emit mercury vapor during the life of the restoration. Controversy surrounds whether fetal exposure to mercury vapor resulting from maternal dental amalgam restorations has neurodevelopmental consequences.
  
  
  METHODS
  The authors determined maternal amalgam restoration status during gestation (prenatal exposure to mercury vapor [Hg(0)]) retrospectively in 587 mother-child pairs enrolled in the Seychelles Child Development Study, a prospective longitudinal cohort study of the effects of prenatal and recent postnatal methylmercury (MeHg) exposure on neurodevelopment. They examined covariate-adjusted associations between prenatal maternal amalgam restoration status and the results of six age-appropriate neurodevelopmental tests administered at age 66 months. The authors fit the models without and with adjustment for prenatal and recent postnatal MeHg exposure metrics.
  
  
  RESULTS
  The mean number of maternal amalgam restorations present during gestation was 5.1 surfaces (range, 1-22) in the 42.4 percent of mothers who had amalgam restorations. The authors found no significant adverse associations between the number of amalgam surfaces present during gestation and any of the six outcomes, with or without adjustment for prenatal and postnatal MeHg exposure. Results of analyses with the secondary metric, prenatal amalgam occlusal point scores, showed an adverse association in boys only on a letter- and word-identification subtest of a frequently used test of scholastic achievement, whereas girls scored better on several other tests with increasing exposure.
  
  
  CONCLUSIONS
  This study's results provide no support for the hypothesis that prenatal Hg(0) exposure arising from maternal dental amalgam restorations results in neurobehavioral consequences in the child. These findings require confirmation from a prospective study of coexposure to MeHg and Hg(0).
authors: Eastman Institute for Oral Health, Department of Environmental Medicine, and Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, N.Y., USA. gene_watson@urmc.rochester.edu
authors: Gene E
authors: GE
authors: Watson
authors: Miranda
authors: M
authors: Lynch
authors: Gary J
authors: GJ
authors: Myers
authors: Conrad F
authors: CF
authors: Shamlaye
authors: Sally W
authors: SW
authors: Thurston
authors: Grazyna
authors: G
authors: Zareba
authors: Thomas W
authors: TW
authors: Clarkson
authors: Philip W
authors: PW
authors: Davidson
mesh_terms: D001724:Birth Weight; D002652:Child Behavior; D002657:Child Development / Q000187:drug effects; D002663:Child Language; D002675:Child, Preschool; D003071:Cognition; D015331:Cohort Studies; D003723:Dental Amalgam; D003793:Dental Restoration, Permanent / Q000706:statistics & numerical data*; D004032:Diet; D005260:Female; D005506:Food Contamination; D006197:Hair / Q000737:chemistry; D006801:Humans; D007360:Intelligence; D008137:Longitudinal Studies; D008297:Male; D008423:Maternal Age; D008628:Mercury / Q000009:adverse effects* / Q000032:analysis; D008767:Methylmercury Compounds / Q000009:adverse effects; D009483:Neuropsychological Tests; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011446:Prospective Studies; D012189:Retrospective Studies; D012737:Sex Factors; D012750:Seychelles; D014796:Visual Perception
chemical_list: D008767:Methylmercury Compounds; D003723:Dental Amalgam; D008628:Mercury