Renal Effects of Dental Amalgam in Children: The New England Children's Amalgam Trial Lars Barregard,1 Felicia Trachtenberg,2 and Sonja McKinlay2 1Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, Gothenburg, Sweden; 2New England Research Institutes, Watertown, Massachusetts, USA Abstract Background: Mercury is nephrotoxic and dental amalgam is a source of mercury exposure. Methods: Children 6–10 years of age (n = 534) with two or more posterior teeth with caries but no prior amalgam restorations, were randomized to one of two treatments—amalgam or resin composite (white fillings) —used for caries treatment during 5 years of follow-up. The primary outcome was change in IQ, but important secondary outcomes were effects on markers of glomerular and tubular kidney function: urinary excretion of albumin, alpha-1-microglobulin (A1M) , -glutamyl transpeptidase ( -GT) , and N-acetyl-β-D-glucosaminidase (NAG) . These markers were measured on several occasions during the trial, together with urinary mercury and covariates. We evaluated the results using repeated-measures analyses. Results: There were no significant differences between treatment groups in average levels of renal biomarkers, nor significant effects of number of dental amalgams on these markers. There was, however, a significantly increased prevalence of microalbuminuria (MA) among children in the amalgam group in years 3–5 (adjusted odds ratio 1.8 ; 95% confidence interval, 1.1–2.9) . Most of these cases are likely to be temporary MA, but 10 children in the amalgam group had MA in both years 3 and 5, versus 2 children in the composite group (p = 0.04) . There were no differences in the occurrence of high levels of renal tubular markers (A1M, -GT, or NAG) . Conclusions: The increase in MA may be a random finding, but should be tested further. The results did not support recent findings in an observational study of an effect of low-level mercury on tubular biomarkers in children. Key words: albumin, alpha-1-microglobulin, children, dental amalgam, -glutamyl transpeptidase, glomerular kidney function, NAG, renal function, tubular kidney function. Environ Health Perspect 116:394–399 (2008) . doi:10.1289/ehp.10504 available via http://dx.doi.org/ [Online 23 November 2007] Address correspondence to S. McKinlay, New England Research Institutes, 9 Galen St., Watertown MA, USA. Telephone: (617) 923-7747. Fax: (617) 926-8246. E-mail: SMckinlay@neriscience.com T.W. Clarkson is acknowledged for contributions to the design of the study and, together with E. Cernichiari, for the analyses of mercury and -GT. L. Andersson is acknowledged for analyses of A1M by ELISA. The study was supported by the National Institute of Dental and Craniofacial Research (U01 DE11886) ; this institute also participated in the design and conduct of the study. The authors declare they have no competing financial interests. Received 25 May 2007 ; accepted 23 November 2007. The full version of this article is available for free in HTML or PDF formats. |