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Milwaukee Journal Sentinel 

Posted Online: February 9, 2008 

Dentists filtering out mercury 

But nearly one-fifth miss MMSD deadline 

By DON BEHM 

dbehm@journalsentinel.com

Dentists throughout Wisconsin are being told they must end routine flushing of mercury 

to sewage treatment plants, where the toxic metal is released to the environment. 

Removing silver-colored fillings from patients' mouths, and placing new silver fillings in, 

are ongoing and significant sources of mercury to sewers, say federal and state 

environmental regulators. They are curtailing discharges of the metal as part of a strategy 

to reduce both contamination of fish in lakes and rivers, and the risk of ill health effects 

to the people who eat those fish. 

Unless there is a large industrial source in a community, about 50% of the mercury in 

wastewater flowing to sewage treatment plants comes from dental offices using silver 

amalgam, said Randy Case, community mercury reduction coordinator with the state 

Department of Natural Resources. 

Any Wisconsin sewage treatment plant that cannot meet stringent mercury discharge 

limits must implement programs in its community to minimize the volume of the metal 

flushed to sewers, Case said. 

The Milwaukee Metropolitan Sewerage District and 25 others in the state are the first 

group required to test treated wastewater for remaining mercury. 

Mandates for dentists 

Though treatment plant operators have approached hospitals, medical clinics and schools 

with voluntary plans to keep mercury out of their drains, MMSD and several other 

municipal wastewater utilities are mandating use of special mercury collection devices at 

dental offices. 

Silver-colored fillings are formed from an amalgam containing 50% liquid mercury and 

several other metals: silver, tin, copper and zinc. Mercury has been used in fillings for 

more than 150 years because it can be easily shaped, is inexpensive and it adheres to a 

tooth under wet conditions inside a mouth. 

Mercury vapor is released from amalgam when a filling is formed and when people chew 

food. No medical studies to date have linked exposure to vapors from amalgam to ill 

health effects in children or adults, according to the U.S. Food and Drug Administration. 
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Use of silver fillings is declining, however, as resin composites and other substitutes 

become more widely used for repairing cavities in teeth. 

Bacteria in lakes and rivers transform elemental mercury to a toxic methyl form that can 

accumulate in fish and damage the health of people who eat the fish. 

Almost all waste amalgam can be removed from a dental office's wastewater through a 

series of relatively inexpensive steps, said Tom Nowicki, a senior industrial waste 

engineer with MMSD. 

A trap in the chair-side vacuum line collects large chunks of the alloy drilled out of teeth. 

And the installation of filters or gravity separators can remove 95% or more of the 

remaining amalgam in the sludge of water, saliva and other fluids suctioned out of a 

mouth, Nowicki said. 

Compliance rate 

Feb. 1 was the final day for dental offices in the Milwaukee Metropolitan Sewerage 

District's four-county service area and in the Racine sewerage district to comply with 

local separator mandates. 

Though they were notified of the deadline four years ago, nearly one-fifth of 313 dental 

offices handling mercury amalgam in MMSD's service area had not complied by Friday, 

Nowicki said. 

The district will send a letter to each of the noncompliant dentists, reminding them of the 

mandate and asking them to comply within the next 30 days, he said. Nowicki also plans 

to visit each of the offices that did not install separators in an attempt to bring them into 

compliance by year's end, he said. MMSD could force dental clinics to install separators 

under its regulation. 

The 81% compliance rate was less than expected, Mequon dentist Dennis Engel said. He 

is the former chairman of the Wisconsin Dental Association's amalgam task force. The 

association has endorsed use of separators to collect waste amalgam. 

"I'm confident we'll have close to 100% compliance soon," Engel said. "Dentists want to 

be good environmental stewards. 

"Some of this might have to do with procrastination in ordering separators and then not 

being able to get them installed by the deadline." 

Among other Wisconsin municipal sewerage districts with 2008 compliance deadlines 

are: Neenah-Menasha, June 1; Oshkosh, Sept. 30; Grand Chute and Menasha West, Oct. 

1; Wausau, Oct. 31; and Madison, Fond du Lac and Green Bay-De Pere, Dec. 31. 
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The Green Bay Metropolitan Sewerage District is offering $500 grants to each of the 100 

dental offices in Green Bay and De Pere that handle mercury amalgam. The grants are 

intended to help pay costs of purchasing and installing separators, said John Kennedy, 

environmental programs manager for the district. 

To date, only 30 dental offices have taken advantage of the offer, he said. 

Waukesha, Watertown, Beloit and La Crosse have set 2009 deadlines. 

Separators cost $600 to $1,500 for dental offices. Marquette University's Dental School 

paid about $6,000 for the separator serving 163 chairs in its clinic, and $2,000 for a 

separator at each of its two off-campus clinics, said Timothy Creamer, a senior associate 

dean with the school. 

Installation can cost an additional $200 to $600 or more. 

Fees for recycling mercury from dental offices vary from $300 to $500 a year, depending 

on the volume. Canisters from separators are simply removed one to two times a year and 

shipped to a licensed mercury recycling company. 

From the Feb. 10, 2008 editions of the Milwaukee Journal Sentinel