Urinary mercury concentrations in Finnish dentists.

During the past few years the safety of amalgam as a dental filling material has been the subject of general public discussion. So far there has been no agreement of whether micromercurialism, a term for the symptoms caused by minute amounts of mercury released from dental fillings, exists or not. Dentists may take mercury into their bodies from amalgam in their dental fillings and from handling it while working. We therefore included determination of urinary mercury concentrations in a comprehensive medical examination programme involving 136 dentists from South-Western Finland. We investigated factors possibly related to observed levels of mercury. The factor most closely related to high urinary mercury levels was use of amalgam by the dentist. Dentists who did not use amalgam had urinary mercury concentrations similar to those in Finns not occupationally exposed to mercury. Their "normal" excretion of mercury into the urine reflected the numbers of their dental fillings made from amalgam. The urinary concentrations of mercury of the dentists who used amalgam in their work were statistically highly significantly elevated. None of the values observed was close to the upper level for safety set by the WHO. However, since only one dentist in eight who used amalgam in their work had urinary mercury levels similar to those in Finns non-exposed to mercury at work, our findings suggest that every dentist should constantly take due care when using amalgam.