Dental Amalgam Restorations and Children's Neuropsychological Function: The New England Children's Amalgam Trial David C. Bellinger,1,2 David Daniel,3 Felicia Trachtenberg,4 Mary Tavares,5 and Sonja McKinlay4 1Department of Neurology, Children's Hospital Boston and Harvard Medical School, and 2Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; 3Department of Psychology, University of Maine at Farmington, Farmington, Maine, USA; 4New England Research Institutes, Watertown, Massachusetts, USA; 5The Forsyth Institute, Boston, Massachusetts, USA Abstract Background: A concern persists that children's exposure to mercury vapor from dental amalgams produces neurotoxicity. Objective: Our goal was to compare the neuropsychological function of children, without prior exposure to dental amalgam, whose caries were repaired using either dental amalgam or mercury-free composite materials. Methods: We conducted a randomized controlled trial involving 534 6- to 10-year-old urban and rural children who were assessed yearly for 5 years using a battery of tests of intelligence, achievement, language, memory, learning, visual–spatial skills, verbal fluency, fine motor function, problem solving, attention, and executive function. Results: Although the mean urinary mercury concentration was greater among children in the amalgam group than the composite group (0.9 vs. 0.6 µg/g creatinine) , few significant differences were found between the test scores of children in the two groups. The differences found were inconsistent in direction. Analyses using two cumulative exposure indices—surface years of amalgam and urinary mercury concentration—produced similar results. Conclusions: Exposure to elemental mercury in amalgam at the levels experienced by the children who participated in the trial did not result in significant effects on neuropsychological function within the 5-year follow-up period. Key words: children, dental amalgam, elemental mercury, neuropsychology, randomized controlled trial. Environ Health Perspect 115:440–446 (2007) . doi:10.1289/ehp.9497 available via http://dx.doi.org/ [Online 30 October 2006] Address correspondence to S. McKinlay, New England Research Institutes, 9 Galen St., Watertown, MA 02472 USA. Telephone: (617) 923-7747. Fax: (617) 926-0144. E-mail: Smckinlay@neriscience.com A. Zhang provided assistance with statistical analyses. This research was supported by a cooperative agreement, U01 DE11886, between the New England Research Institutes and the National Institute of Dental and Craniofacial Research. The authors declare they have no competing financial interests. Received 8 July 2006 ; accepted 30 October 2006. The full version of this article is available for free in HTML or PDF formats. |