title: Renal effects of dental amalgam in children: the New England children's amalgam trial.
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), gamma-glutamyl transpeptidase (gamma-GT), and N-acetyl-beta-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, gamma-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.
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, Gothenburg, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Barregard
authors.forename: Felicia
authors.initials: F
authors.lastname: Trachtenberg
authors.forename: Sonja
authors.initials: S
authors.lastname: McKinlay
mesh_terms: D000118:Acetylglucosaminidase / Q000648:ultrastructure; D000510:Alpha-Globulins / Q000032:analysis; D015415:Biomarkers / Q000652:urine; D002648:Child; D003723:Dental Amalgam / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007360:Intelligence / Q000187:drug effects*; D007674:Kidney Diseases / Q000139:chemically induced* / Q000503:physiopathology / Q000523:psychology; D007677:Kidney Function Tests; D008297:Male; D009511:New England; D012709:Serum Albumin / Q000032:analysis; D013997:Time Factors; D005723:gamma-Glutamyltransferase / Q000652:urine
chemical_list: D000510:Alpha-Globulins; D015415:Biomarkers; D012709:Serum Albumin; C016001:alpha-1-microglobulin; D003723:Dental Amalgam; D005723:gamma-Glutamyltransferase; D000118:Acetylglucosaminidase