How are Dental Mercury Discharges Regulated?

The Canadian Council of Ministers of the Environment (CCME), an intergovernmental council made up of the 14 ministers of the environment for the federal, provincial and territorial governments, endorsed the Canada-wide Standard for Dental Amalgam Waste at their September 22-23, 2001 meeting.

The Canada-wide Standard (CWS) for Dental Amalgam Waste sets a national reduction target based on best management practices to achieve a voluntary 95% reduction in mercury releases from dental amalgam waste by 2005, from a base year of 2000. The CCME will receive reports by jurisdictions and/or partners in the delivery of this standard in 2004 and 2007. The 2007 report will include an evaluation of this standard and a recommendation as to whether changes should be considered. The initial set of actions for the CWS require the Government of Canada to (i) develop a Memorandum of Understanding between Environment Canada and the Canadian Dental Association to lay out the commitments by dentists to implement the standard; (ii) develop tools to aid municipalities in identifying and reducing sources of mercury discharges to sewers; and (iii) develop an annual inventory of municipal sewage sludge quality as an indicator of treatment plant influent loading by mercury. The agreement also sets out various actions to be undertaken by the provincial governments.

But this is just a voluntary process. Most of the real action on reducing mercury waste from dentists' offices is happening at the municipal level.

In 2000, the City of Toronto passed the most progressive sewer use by-law in Ontario. The by-law requires dentists to install amalgam separators; prepare and submit pollution prevention plans; and cut their mercury discharges to the sewer to less than 0.01 mg/L. For more information about this by-law contact Victor Lim, Manager, Industrial Waste and Stormwater Quality, City of Toronto at (416) 392-2966 or e-mail VLim@city.toronto.on.ca.

Montreal, Calgary and Victoria have also enacted by-laws recently requiring dental amalgam separators and the virtual elimination of mercury discharge from dentists' offices to sewers and the City of Kingston has adopted the 0.01 mg/L discharge limit for mercury to its sewer system.

In a 1998 study in the U.S., the average local limits on industrial discharges of mercury to the sewer system was 0.0875 mg/L.

Prince Edward Island is the first province in Canada to undertake a province-wide effort to remove dental amalgam mercury from municipal wastewater. It is a joint effort involving the PEI Department of Fisheries, Aquaculture and Environment, Environment Canada and the Dental Association of PEI. It consists of two phases. First an assessment will take place of the feasibility of installing amalgam separators in all dental offices in the province. The study will look at equipment costs, installation costs, and waste disposal options. Should the phase one evaluation prove the viability of the project, then phase two will commence wherein mercury amalgam separators will be installed in six Island dentists' offices for a pilot study. Sludge samples will be collected in the sewer lines beneath the six dental offices (before equipment installation and then regularly thereafter), and at selected sewage treatment plants. If mercury levels have been reduced significantly, amalgam separators will be installed in every dentist's office in PEI. For more information on this pilot project contact Todd Fraser, Air Quality and Hazardous Materials, PEI Department of Fisheries, Aquaculture and Environment at (902) 368-5037 or e-mail ktfraser@gov.pe.ca.