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Hazard Communication Compliance and Waste Management

Course Number: 697

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Mercury-containing Waste: Scrap Amalgam

Dental amalgam is a mixture of two nearly equal parts of liquid mercury (D009) and a powder containing silver (D011), tin, copper, zinc and other metals. When amalgam restorations are placed in or removed from teeth, or during chewing, a small amount of mercury vapor is released.17 Although the vapor may be absorbed by inhalation or ingestion, the FDA considers amalgam restorations safe for adults and children over the age of six.

However, amalgam waste not captured or removed at the dental office is discharged into a sanitary sewer system and transferred to publicly-owned treatment works (POTWs), i.e., sewage treatment plants. POTWs remove about 95 percent of the amalgam waste, which then becomes part of the POTWs sewage sludge. This mercury containing sludge may then be disposed of in landfalls, incinerated, or applied to agricultural land as fertilizer, releasing mercury into the ground water or air. Airborne mercury is eventually deposited onto surface water, land and vegetation. Mercury is a persistent and bio-accumulative pollutant in the environment with well-documented neurotoxic effects on humans.

On June 14, 2017, the EPA finalized specific regulatory guidance to require dental practices to comply with requirements for controlling the discharge of mercury and other metals in dental amalgam into POTWs based on the best available technology.18 Most dental offices already use some type of basic filtration system (chairside traps, vacuum pump filters); in addition, the EPA regulatory guidance enacted in 2017 required non-exempt dental offices to install amalgam separators by 2020.18

Amalgam separators are devices designed to remove amalgam particles from dental office wastewater through sedimentation, filtration, centrifugation, chemical removal by ion exchange or a combination of these technologies. Amalgam separators that meet the International Organization for Standardization (ISO) standard (ISO 11143) can capture over 95 percent of the amalgam waste discharged by dental offices into sanitary sewer systems.19,20

The ADA encourages dentists to implement best management practices (BMPs) to help reduce the environmental effects of amalgam waste (Box I).

Box I. Best management practices for the disposal of mercury-containing scrap amalgam.19,20

  • Stock pre-capsulated amalgam alloys in a variety of sizes instead of bulk elemental mercury to minimize the amount of hazardous mercury-containing amalgam waste generated.
  • Collect and store used disposable amalgam capsules in a wide-mouthed, airtight container labeled “Hazardous Waste - Amalgam Capsules.”
    • Once the container is full, have an approved hazardous waste transporter deliver it to an approved hazardous waste management facility.
    • DO NOT PLACE AMALGAM CAPSULES IN NON-HAZARDOUS OFFICE WASTE OR REGULATED MEDICAL WASTE CONTAINERS.
  • Use chairside disposable or reusable traps, vacuum pump filters and an ISO 11143-compliant amalgam separator to capture amalgam particles generated when removing old or carving new amalgam restorations.
    • Chairside trap – when the trap is full, remove trap according to manufacturer’s recommendations. If reusable, clean according to manufacturer’s recommendations. Place contents and any disposable traps in a wide-mouthed, airtight container labeled “Hazardous Waste – Scrap Amalgam.”
    • Once the container is full, have an approved hazardous waste transporter deliver it to an approved hazardous waste management facility. a. DO NOT RINSE DISPOSABLE CHAIRSIDE TRAPS THAT CONTAIN AMALGAM PARTICLES IN THE SINK. b. DO NOT TROW DISPOSABLE CHAIRSIDE TRAPS THAT CONTAIN AMALGAM PARTICLES IN NON-HAZARDOUS OFFICE WASTE OR REGULATED MEDICAL WASTE CONTAINERS.
    • Vacuum pump filter – change filter according to manufacturer’s recommendations, put the lid on the filter and place it in the box in which it was originally shipped. Once the box is full, have an approved hazardous waste transporter deliver it to an approved hazardous waste management facility.
      • DO NOT RINSE VACUUM PUMP FILTERS THAT CONTAIN AMALGAM PARTICLES IN THE SINK.
      • DO NOT TROW DISPOSABLE VACUUM PUMP FILTERS THAT CONTAIN AMALGAM IN NON-HAZARDOUS OFFICE WASTE OR REGULATED MEDICAL WASTE CONTAINERS.
    • Amalgam separators -- Follow manufacturer’s recommendations for maintenance and recycling procedures.
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