Mercury vapour release from a dental aspirator

Objective To investigate the release of mercury vapour from a dental aspira tor which vented its waste air through its base directly into the surgery e nvironment. Methodology Mercury vapour in air concentrations were measured at the breat hing zone of the dentist during continuous operation of the aspirator. Furt her series of mercury vapour measurements taken at the aspirator exhaust ve nt were carried out to determine the sources of mercury vapour from this pa rticular device. Results At the dentist's breathing zone, mercury vapour concentrations of t en times the current occupational exposure limit of 25 mug/m(3) were record ed after 20 minutes of continuous aspirator operation. A build up of amalga m contamination within the internal corrugated tubing of the aspirator was found to be the main source of mercury vapour emissions followed by particu late amalgam trapped within the vacuum motor. As the vacuum motor heated up with run time, mercury vapour emissions increased. It was found that the b acterial air exhaust filter (designed to clean the contaminated waste air e ntering the surgery) offered no protection to mercury vapour. In this case the filter trapped particulate amalgam which contributed to further mercury vapour contamination as high volume air was vented through it. Conclusion It is not known how many dental aspirators are in use that vent their waste air directly into the surgery or if this aspirator is represent ative of others in existence. The safety of dental aspirating systems with regard to mercury vapour exposure requires further investigation.