Thirty-five year review of a mercury monitoring service for Scottish dental practices.

AIMS AND OBJECTIVES

To review a long-standing mercury monitoring service offered to staff in dental practices in Scotland.

METHODS

During the first 20 years of the service, dentists and their staff were contacted by letter and invited to participate. Respondents were asked to collect samples of head hair, pubic hair, fingernail and toenail for analysis of mercury. After 1995, head hair samples were collected initially and further samples were only measured if head hair mercury was elevated.

RESULTS

At the start of this scheme many staff, including administrative staff, had systemic exposure to mercury (defined as increased mercury in all four samples). Incidents of exposure have decreased over the 35 years and are now very rare. Male staff were found to have higher mercury concentrations than female staff and dentists tended to have higher concentrations than other staff. Staff working in dental practices more than five years old had small but discernable increases in head hair mercury concentration. In recent years the use of reusable capsules such as Dentomats has been associated with a slight but statistically significant increase in head hair mercury concentrations when compared to the use of encapsulated amalgam systems. Staff wearing open-toed footwear had significantly higher toenail mercury concentrations compared to those who wore shoes.

CONCLUSIONS

Exposure of staff to mercury in Scottish dental practices is currently now very low. This is probably as a result of increased awareness to the toxicity of mercury and improved methods of preparing amalgam. It may be possible to reduce exposure further, although probably only slightly, by upgrading practices and using encapsulated mercury amalgam.