Smile! Dental waste reduction program celebrates five successful years

Local dentists are giving King County residents yet another reason to smile.

Since July 2003, they’ve kept about 375 pounds of mercury out of the environment by complying with regulations established by the county’s Wastewater Treatment Division and its Industrial Waste Pretreatment Program.

Dental offices are considered a significant source of mercury because of its presence in silver-colored amalgam tooth fillings.

To prevent mercury and other metals from going down drains, King County now requires the 900 or so dental offices operating in King County to either install an amalgam separator or obtain a county permit and demonstrate compliance with discharge limits of 0.2 parts per million of total mercury.

The county’s program has caught the attention of the U.S. Congress. This week, Industrial Waste Compliance Investigator Patricia Magnuson was invited to provide testimony on the program and its outcome to date at a Domestic Policy subcommittee hearing, Assessing State and Local Regulations to Reduce Dental and Mercury Emissions.

“When dental offices and other industries keep harmful chemicals and heavy metals out of the wastewater system, it helps us protect the quality of the water and biosolids we reclaim for beneficial uses,” said Wastewater Treatment Division Director Christie True.

According to True, the amount of mercury in our biosolids was far below the U.S. Environmental Protection Agency’s Exceptional Quality standards before the program began.

“Since the dental waste discharge requirements became mandatory in 2003, we’ve managed to reduce mercury concentrations by an additional 50 percent, significantly improving an already high quality product,” she said.

Industrial Waste program employees worked with the Seattle-King County Dental Society to develop the regulations. The county has an ongoing outreach and education program to answer questions and support compliance. Inspectors visit the dental offices annually.

While the county considers the program a success, True said that local communities need to have the flexibility to develop their own mercury waste reduction policies programs. The county’s division supports the National Association of Clean Water Agencies position against legislation at the federal level.

People enjoy clean water and a healthy environment because of King County's wastewater treatment program. The county’s Wastewater Treatment Division protects public health and water quality by serving 17 cities, 17 local sewer districts and more than 1.4 million residents in King, Snohomish and Pierce counties. Formerly called Metro, the regional clean-water agency now operated by King County has been preventing water pollution for more than 40 years.

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Note to editors and reporters: Visit the WTD Newsroom, a portal to information for the news media about the Wastewater Treatment Division, King County Department of Natural Resources and Parks: http://dnr.metrokc.gov/wtd/newsroom/.

Related Information

Industrial Waste Program

King County Wastewater Treatment Division

Mercury - LHWMP