Arenholt-Bindslev D. Dental amalgam—environmental aspects. Advances in Dental Research. 1992 Sep;6(1):125-30.

Major amalgam particles from trituration surplus of those produced during the carving and burnishing of new amalgam restorations are generally collected in coarse filters and sold for refinement. Minor amalgam particles released by production of new fillings or by removal of old restorations partly sediment in tubes and drains. The remaining particles are carried with the waste water stream to the local purifying plant.

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