Solid Waste & Recycling


Next phase of mercury waste by-law to take effect soon

Environmental group RiverSides Stewardship Alliance recently announced that mercury levels in Toronto's sewers have...

Environmental group RiverSides Stewardship Alliance recently announced that mercury levels in Toronto’s sewers have decreased by between 40 per cent and 68 per cent since the Sewer Use By-law for the City of Toronto came into effect on January 1, 2002. The by-law requires about 1,500 dental practices to use dental amalgam separators in their sinks and to drain plumbing to prevent mercury-laden wastewater from entering sewers.

Mercury from Toronto’s sewers ends up in Lake Ontario or as contamination in sewage sludge. A recent report from the U.S. group Health Care Without Harm cites dentists offices as the largest single source of mercury pollution in municipal sewer systems. The U.S. National Academy of Sciences estimates that in the U.S., 60,000 babies are born learning disabled due to mercury levels in the fetus and that over two million pregnant woman are exposed to high levels of mercury from the consumption of fish annually.

The next phase of the Toronto by-law is due to come into force on November 1, 2002. Dentists will be required to limit their mercury discharges to less than 0.01 mg/L — the strictest limit in Canada — or face fines of $10,000 to $100,000 per day. Toronto Council has already approved six new enforcement officers to monitor compliance. Private citizens and environmental groups can also launch private prosecutions against dentists and property owners who fail to comply with the by-law.

These other Canadian cities also require dentists to install amalgam separators: Calgary, Alberta; Montreal, Quebec; and, Victoria, B.C.

For more information, contact Jason Thorne of the RiverSides Stewardship Alliance at 416-392-1983 or or visit

Also read the Cover Story in the April/May 2002 edition of SW&R, "A solid approach to control the content of sludge…What’s It?"

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