Mercury from dental amalgam waste most commonly enters the wastewater stream by being rinsed down drains or by accidentally escaping from chairside traps and filters. Mercury that enters the wastewater stream eventually enters the septic system, leading into sewage or in liquid effluent that eventually makes its way into lakes and rivers.
Mercury-containing amalgam scrap can contaminate soil and water if it ends up in a landfill, which happens when it is improperly discarded into ordinary trash containers. It is also important to note that dental waste, such as amalgam scrap, should never be treated as medical waste. If disposed of into red bags or other medical waste containers that are autoclaved or incinerated, mercury will enter the atmosphere and eventually contaminate waterbodies or ground soil via precipitation.
The following is a list of items that are considered mercury waste and must be disposed of properly: