Volume 65, Issue 5 (3 2007)                   Tehran Univ Med J 2007, 65(5): 78-83 | Back to browse issues page

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Abstract:   (7672 Views)
Background: Dental amalgam, a mixture of approximately 50% mercury with silver, tin, zinc and copper in varying ratios, is a major source of mercury pollution in the general population not occupationally exposed. The toxicity of mercury is enhanced because it is so readily absorbed, with around 90-100% of mercury vapor being absorbed through the oral mucosa. The aim of the current study is to examine the mercury levels in hair and nails in subjects with amalgam fillings.
Methods: For a sample of forty university students reporting infrequent fish consump-tion, with their only known exposure to mercury from amalgam fillings, mercury levels were measured in hair and nail samples using the LECO AMA 254 Advanced Mercury Analyzer (USA), according to the ASTM standard No. D-6722 test method.
Results: Mercury concentration in hair ranged from 0.09 to 3.11 mg/kg, and in nail from zero to 1.35 mg/kg. We found that subjects with five or more amalgam fillings had significantly higher levels in their hair than subjects with zero to 5 amalgam fillings (CI 95% P=0.003). However, the number of amalgam fillings had no effect on the mercury concentration in nails in these two groups (P=0.26). There was no significant difference between the levels of mercury of males and that of females tested (P=0.26 for nail and P=0.15 for hair).
Conclusion: The mercury amount in hair was 1.5 times as much as that of the nail samples, may be due to the differences in the chemical compounds, particularly those with sulfur, or the deposition of those compounds that would be affected by blood circulation during formation of hair and nails. Although the amounts of mercury found in this study were below the WHO maximum acceptable level of 6 mg/kg for mercury in human hair, the levels were sufficient to warrant the use of other dental materials such as composites in order to decrease the overall rate of exposure to mercury.
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