LONG-TERM MERCURY EXCRETION IN URINE AFTER REMOVAL OF AMALGAM FILLINGS

The long-term urinary mercury excretion was determined in 17 28- to 55 -year-old persons before and at varying times (up to 14 months) after removal of all (4-24) dental amalgam fillings. Before removal the urin ary mercury excretion correlated with the number of amalgam fillings. In the immediate post-removal phase (up to 6 days after removal) a mea n increase of 30% was observed. Within 12 months the geometric mean of the mercury excretion was reduced by a factor of 5 from 1.44 mu g/g ( range: 0.57-4.38 mu g/g) to 0.36 mu g/g (range: 0.13-0.88 mu g/g). Aft er cessation of exposure to dental amalgam the mean half-life was 95 d ays. These results show that the release of mercury from dental amalga m contributes predominantly to the mercury exposure of non-occupationa lly exposed persons. The exposure from amalgam fillings thus exceeds t he exposure from food, air and beverages. Within 12 months after remov al of all amalgam fillings the participants showed substantially lower urinary mercury levels which were comparable to those found in subjec ts who have never had dental amalgam fillings. A relationship between the urinary mercury excretion and adverse effects was not found. Diffe rences in the frequency of effects between the pre- and the post-remov al phase were not observed.