DAILY DOSE CALCULATIONS FROM MEASUREMENTS OF INTRAORAL MERCURY-VAPOR

Measurements of intra-oral mercury vapor from amalgam fillings are discussed. It was shown that the only quantity which it is possible to measure is the mercury release rate, and that the concentrations of mercury vapor in the oral cavity published in most earlier studies are the mercury concentrations in the measuring cell of the measuring apparatus and not the concentrations in the oral cavity. The Consequences for the daily dose equations of the facts that the mercury source is present inside the oral cavity and that the amount of mercury released during a certain time is limited are discussed. It was found that most daily dose equations used have a questionable mercury distribution on inspiration, expiration, and swallowing. Re-calculations of almost all the available daily dose data showed a mean daily dose value of about 1.3-mu-g Hg/day (range, 0.3-2.2-mu-g Hg/day). The mean swallowed amount of mercury from intra-oral mercury vapor was calculated as being in the order of 10-mu-g Hg/day (range, 2.4-17-mu-g Hg/day), resulting in an estimated absorption of about 1-mu-g Hg/day from the gastro-intestinal tract.