Combined estimation of mercury species released from amalgam.

Amalgam fillings constitute, after food, the main source of exposure to mercury for the general population. Banning amalgam would incur huge costs for additional dental treatment. An evaluation of potential health risks must be based on the mercury dose released from fillings. In this study, dose is estimated by a new procedure of mercury speciation which elutes the released elemental and inorganic mercury with solvents of differing polarity. We tested the procedure by incubating spherical amalgam pellets in a mixture of light paraffin oil and saline (0.9% NaCl). Release of mercury into paraffin and saline was linear in relation to both amalgam surface area and exposure time. Measurements with this method were then extended to a group of 21 amalgam-bearing volunteers. The absorbed dose averaged 4.8 micrograms/day compared with 3.7 measured conventionally in intra-oral air from the same persons. With both methods, the dose was significantly correlated to the number of amalgam-covered tooth surfaces. This dose, combined with the nearly equal mercury uptake from food, is far below the acceptable daily intake limit.