Dentin as a possible bio-epidemiological measure of exposure to mercury

The subtle human health effects from prolonged exposure to small amounts of mercury vapor are unknown. It has been difficult to study possible effects of low-dose exposure for lack of a good measure of long-term exposure. Current methods which use blood, urine, hair, and nails reliably measure only recent exposures. Long-term exposure to lead has been measured using levels found in human dentin. The purpose of this study was to determine whether mercury also accumulates in dentin. In this study, dentin from 16 human teeth, all without dental amalgam restorations, was analyzed by thermal neutron activation analysis. The teeth were selected from people with and without dental mercury amalgam restorations elsewhere in their dentitions. Mercury was found in amounts up to 5.9 ppm. While the highest mercury level was from a sample from someone who had dental amalgam restorations elsewhere in their dentition, the second highest was from someone who had no amalgam restorations. Also, a sample which was not used for any statistical comparisons but which was analyzed because the tooth contained an amalgam restoration had one of the lowest levels of mercury. These results, while inconclusive due to a small sample size, suggest that inorganic mercury vapor is a relatively small contributor to the overall body burden of mercury.