Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Randomized Controlled Trial
. 2008 Mar;116(3):394-9.
doi: 10.1289/ehp.10504.

Renal effects of dental amalgam in children: the New England children's amalgam trial

Lars Barregard  1 , Felicia Trachtenberg, Sonja McKinlay
Affiliations
Randomized Controlled Trial

Renal effects of dental amalgam in children: the New England children's amalgam trial

Lars Barregard et al. Environ Health Perspect. 2008 Mar.

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.

Keywords: NAG; albumin; alpha-1-microglobulin; children; dental amalgam; glomerular kidney function; renal function; tubular kidney function; γ-glutamyl transpeptidase.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Distribution of U-Hg in children treated with amalgam or composite dental fillings in years 3–5 of the 5-year New England Children’s Amalgam Trial. The boxplots show the median (middle line), 25th and 75th percentiles (box), the extreme values (whiskers of 1.5 times the interquartile range), and the outliers (highest values).
Figure 2
Figure 2
Urinary excretion of (A) γ-GT, (B) albumin, and (C) NAG by number of amalgam fillings in year 5 of the New England Children’s Amalgam Trial. Sample sizes are slightly higher for γ-GT because priority was given to this assay. Samples of sufficient volume were also analyzed for albumin and NAG. Numbers above the bars are percentages of (A) high γ-GT, (B) MA, and (C) high NAG.
See this image and copyright information in PMC

Comment in

  • Taking a bite out of amalgam concerns?
    McGovern V. McGovern V. Environ Health Perspect. 2008 Mar;116(3):A129. doi: 10.1289/ehp.116-a129a. Environ Health Perspect. 2008. PMID: 18335089 Free PMC article. No abstract available.

References

    1. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Mercury. Atlanta, GA: Agency for Toxic Substances and Disease Registry; 1999.
    1. American Diabetes Association. Nephropathy in diabetes. Diabetes Care. 2004;27(suppl 1):S79–S83. - PubMed
    1. Barregard L. Biological monitoring of exposure to mercury vapor. Scand J Work Environ Health. 1993;19(suppl 1):45–49. - PubMed
    1. Barregard L, Enestrom S, Ljunghusen O, Wieslander J, Hultman P. A study of autoantibodies and circulating immune complexes in mercury-exposed chloralkali workers. Int Arch Occup Environ Health. 1997;70(2):101–106. - PubMed
    1. Barregard L, Horvat M, Mazzolai B, Sällsten G, Gibicar D, Fajon V, et al. Urinary mercury in people living near point sources of mercury emissions. Sci Total Environ. 2006;368:326–334. - PubMed

Publication types