The effect of disinfectants and line cleaners on the release of mercury from amalgam

Backround. Dental practices use disinfectants or line cleaners to flush dental unit wastewater lines to minimize odor generation, remove solid waste particles and remove biofilms in dental unit water lines (DUWLs). Methods. The authors evaluated 47 disinfectants or line cleaners for their potential to release mercury from amalgam waste. They prepared each product concentration according to the manufacturer's recommendations and gently agitated it along with one amalgam specimen for 24 hours. They filtered the combined decanted liquid and rinse and analyzed it for mercury using modified U.S. Environmental Protection Agency method 245.1. Results. Six preparations released significantly more mercury from amalgam (about 17 to 340 times) than did the deionized water control (P < .001). The amount of mercury released by the other disinfectants/line cleaners was not statistically different from that released by the control. The pH values of all preparations ranged from 1.76 to 12.35. Conclusion and Clinical implications. This study and other published reports have demonstrated that preparations containing chlorine release more mercury from amalgam than did some other products and the deionized water control. As a result, the use of these products is not recommended for treating dental office wastewater lines or DUWLs.