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Pam Factor-Litvak,^1,2 Gunnar Hasselgren,³ Diane Jacobs,⁴ Melissa Begg,⁵ Jennie Kline,^1,4,6 Jamie Geier,¹ Nancy Mervish,¹ Sonia Schoenholtz,¹ and Joseph Graziano²

¹Department of Epidemiology and ²Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA; ³School of Dental and Oral Surgery, Columbia University, New York, New York, USA; ⁴Sergievsky Center, Columbia University, New York, New York, USA; ⁵Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, New York, USA; ⁶Epidemiology of Developmental Brain Disorders Department, New York State Psychiatric Institute, New York, New York, USA

Abstract

There is widespread concern regarding the safety of silver-mercury amalgam dental restorations, yet little evidence to support their harm or safety. We examined whether mercury dental amalgams are adversely associated with cognitive functioning in a cross-sectional sample of healthy working adults. We studied 550 adults, 30-49 years of age, who were not occupationally exposed to mercury. Participants were representative of employees at a major urban medical center. Each participant underwent a neuropsychologic test battery, a structured questionnaire, a modified dental examination, and collection of blood and urine samples. Mercury exposure was assessed using a) urinary mercury concentration (UHg) ; b) the total number of amalgam surfaces ; and c) the number of occlusal amalgam surfaces. Linear regression analysis was used to estimate associations between each marker of mercury exposure and each neuropsychologic test, adjusting for potential confounding variables. Exposure levels were relatively low. The mean UHg was 1.7 µg/g creatinine (range, 0.09-17.8) ; the mean total number of amalgam surfaces was 10.6 (range, 0-46) and the mean number of occlusal amalgam surfaces was 6.1 (range, 0-19) . No measure of exposure was significantly associated with the scores on any neuropsychologic test in analyses that adjusted for the sampling design and other covariates. In a sample of healthy working adults, mercury exposure derived from dental amalgam restorations was not associated with any detectable deficits in cognitive or fine motor functioning. Key words: attention, cognition, dental amalgams, memory, mercury exposure, neuropsychologic function. Environ Health Perspect 111:719-723 (2003) .