title: Amalgam exposure and neurological function.
abstract: Concerns regarding the safety of silver-mercury amalgam fillings continue to be raised in the absence of any direct evidence of harm. The widespread population exposure to amalgam mandated that a thorough investigation be conducted of its potential effects on the nervous system. The National Institute of Dental and Craniofacial Research and U.S. Air Force investigators collaborated in the ongoing Air Force Health Study (AFHS) of Vietnam era veterans. The primary study question involved adverse health effects associated with exposure to herbicides or dioxin. An assessment of exposure to dental amalgam fillings was added to the 1997-1998 health examination to investigate possible associations between amalgam exposure and neurological abnormalities. Our study population consisted of 1663 dentate AFHS participants, comprised of 986 AFHS controls and 677 Ranch Hand veterans who were exposed to dioxin in Vietnam. Two hundred and fifty-two of the participants had confirmed diabetes mellitus. Study outcomes included clinical neurological signs, vibrotactile thresholds, and summary variables for different levels of peripheral neuropathy. A limitation of our study is that our database did not include more sensitive continuous measures such as nerve conduction studies. No significant associations were found between amalgam exposure and clinical neurological signs of abnormal tremor, coordination, station or gait, strength, sensation, or muscle stretch reflexes or for any level of peripheral neuropathy among our study participants. A statistically significant association was detected between amalgam exposure and the continuous vibrotactile sensation response for the combined non-diabetic participants and separately for non-diabetic AFHS controls. No significant association in this measure was detectable for non-diabetic Ranch Hand veterans or among the combined diabetic participants. The association is a sub-clinical finding that was not associated with symptoms, clinically evident signs of neuropathy, or any functional impairment. Overall, we found no association between amalgam exposure and neurological signs or clinically evident peripheral neuropathy. Our findings do not support the hypothesis that exposure to amalgam produces adverse, clinically evident neurological effects.
authors.affiliation: Division of Clinical Research and Health Promotion, National Institute of Dental and Craniofacial Research, National Institutes of Health, 45 Center Drive, Room 4As-25U, Bethesda, MD 20892-6401, USA. Albert.Kingman@nih.gov
authors.forename: Albert
authors.initials: A
authors.lastname: Kingman
authors.forename: James W
authors.initials: JW
authors.lastname: Albers
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Arezzo
authors.forename: David H
authors.initials: DH
authors.lastname: Garabrant
authors.forename: Joel E
authors.initials: JE
authors.lastname: Michalek
mesh_terms: D003723:Dental Amalgam / Q000009:adverse effects*; D003943:Diagnostic Techniques, Neurological; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010523:Peripheral Nervous System Diseases / Q000139:chemically induced* / Q000453:epidemiology*; D014481:United States; D014728:Veterans
chemical_list: D003723:Dental Amalgam